GTZ - CRYSTAL 3 - Part 4 - cd3wd404.zip - Small Projects Training Manual

GTZ - CRYSTAL 3 - Part 4 - cd3wd404.zip - Small Projects Training Manual
0. Introduction
2
TABLE OF CONTENTS
0. Introduction.......................................................................................................................... 2
0.2 Foreword .......................................................................................................................... 5
0.3 Purpose of the Manual..................................................................................................... 6
0.4 Possible Readers of the Manual ...................................................................................... 7
0.5 Summary of the Contents ................................................................................................ 8
0.6 Format and Style of the Manual....................................................................................... 9
0.7 Instructions on how to Use the Manual.......................................................................... 11
0.8 Instructions how to Teach with the Manual.................................................................... 12
5. Mathematics ....................................................................................................................... 15
5.1 Basic Calculations.......................................................................................................... 15
5.2 Percent Calculations ...................................................................................................... 20
5.3 Measurements ............................................................................................................... 22
5.4 Basic Geometry.............................................................................................................. 27
5.5 Calculation of Diagonal .................................................................................................. 41
5.6 Calculation of Volumes .................................................................................................. 43
5.7 Calculation of Weights ................................................................................................... 45
5.8 Calculation of Time ........................................................................................................ 46
6. Basic Technical Knowledge ............................................................................................. 48
6.1 Basic Technical Drawing................................................................................................ 48
6.2 Marking Rectangular Layout Plan.................................................................................. 77
6.3 Tools .............................................................................................................................. 81
6.4 Using Measuring Tools ................................................................................................ 102
6.5 Building and Other Materials........................................................................................ 109
6.6 Cement and Concrete.................................................................................................. 117
6.7 Bricklaying.................................................................................................................... 128
6.8 Improved Local Building............................................................................................... 141
7. Building Administration.................................................................................................. 146
7.1 Planning ....................................................................................................................... 146
7.2 Work Records .............................................................................................................. 149
7.3 Records of Materials .................................................................................................... 152
7.4 Cost Calculation for Community Work ......................................................................... 153
7.5 Cost Calculation for Contract Work.............................................................................. 160
7.6 Purchasing Locally....................................................................................................... 161
7.7 Purchasing from Khartoum .......................................................................................... 163
7.8 Purchasing from Abroad .............................................................................................. 165
7.9 Storekeeping - Recording ............................................................................................ 167
7.10 Organising a Store ..................................................................................................... 169
7.11 Storekeeping - Procedures ........................................................................................ 174
7.12 Stock-Taking .............................................................................................................. 177
8. Water Supply.................................................................................................................... 180
8.1 Story about Good Water Supply .................................................................................. 180
8.2 Connection of Water Supply with the Community ....................................................... 181
8.3 Process of Community Development - Water Supply Cooperation............................. 182
8.4 Cooperation of Water Supply Technicians with the Community.................................. 182
8.5 Importance of Adequate Water Supply........................................................................ 183
8.6 Water Related Diseases .............................................................................................. 184
8.7 Basic Facts about Water.............................................................................................. 188
8.8 Groundwater ................................................................................................................ 191
8.9 Desertification .............................................................................................................. 197
8.10 Wells .......................................................................................................................... 198
8.11 Comparison of Borehole and Hand Dug Well............................................................ 202
8.12 Selection of Well Sites ............................................................................................... 204
8.13 Site Survey by Hand Augering................................................................................... 205
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8.14 Construction Methods for Hand Dug Wells................................................................ 217
8.15 Well Digging Techniques ........................................................................................... 225
8.16 Manufacturing Concrete Rings .................................................................................. 229
8.17 Lowering Concrete Rings into a Well......................................................................... 240
8.18 Manufacturing a Well Cover....................................................................................... 262
8.19 Well Head with Hand Pump ....................................................................................... 270
8.20 Completion of a Well.................................................................................................. 275
8.21 Safety Measures ........................................................................................................ 277
8.22 Ventilation in Wells..................................................................................................... 280
8.23 Ropes and Knots ....................................................................................................... 283
8.24 Types of Pumps and Other Water Lifting Devices..................................................... 284
8.25. Dewatering Wells during Construction...................................................................... 316
8.26. Diaphragm Pumps .................................................................................................... 317
8.27 Fuel-Powered Suction Pumps ................................................................................... 320
8.28. Submersible Pumps.................................................................................................. 324
8.29. Drawing Water from a Well for Human Consumption............................................... 327
8.30. Hand Pump Parts and Functions.............................................................................. 332
8.31. Hand Pump Installation............................................................................................. 337
8.32. Basic Plumbing ......................................................................................................... 344
8.33. Hand Pump Caretaking............................................................................................. 360
8.34. Calculation of Pump Discharge................................................................................. 361
8.35. Spring Protection ...................................................................................................... 363
8.36. Well Disinfection ....................................................................................................... 372
8.37. Water Treatment at Home ........................................................................................ 378
8.38. Handling Water at Home........................................................................................... 384
8.39. Health Education about Water/Operating Instruction for Wells ................................ 391
10. Appendix ........................................................................................................................ 396
10.1. List of Abbreviations.................................................................................................. 396
10.4. List of Illustrations (from literature) ........................................................................... 396
10.5. Bibliography .............................................................................................................. 397
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0.2 Foreword
Two people are named as authors of this training manual; however, in reality it is the result of
the work of very many people. We hope that it will serve a great number of people as well.
The development of the manual has a long history. We had the opportunity to work with the
Sudan Council of Churches from 1982 to 1987, first in the Integrated Rural Development
Programme in Yirol, and then in the Munuki Water and Sanitation Project in Juba, both in
Southern Sudan. We had been assigned as Water Supply Coordinator (Marta) and
Community Development Coordinator (Rudi). In the beginning we had background knowledge
but little field experience. So we started to learn with and from the people and from the
literature. At the same time we started training the people with whom we worked. In the
beginning the training was exclusively on site. However, in the second project, the training
became more formalised into a full two years programme of both class and field work. We
began from the actual level of knowledge of the trainees without the assumption that “one
should know this or that”, and gathered whatever knowledge was necessary to do the project
work together. Soon, compiling and distributing of written material became necessary, and so
this manual was begun.
It includes many of our experiences in the water and sanitation work during the last five years.
The bulk of the information was ready in first draft in April 1987. Photocopies were distributed
to the participants of a three months training course. Contributions and questions from the
participants were invaluable, and many sections were revised/improved. Actually, the manual
would have never been written without the eagerness of the Munuki project’s staff to learn.
This interest made learning and teaching very enjoyable. After the training course, the entire
manual was revised further and finally completed to the present version.
We thank our colleagues in the Munuki Water and Sanitation Project for all we learned from
them, for their good cooperation and for their contributions to the manual. They are:
Edward Lako, Arthur A.Columbano Lado, Rhoda Benjamin, Joseph Lado Lubajo, Joan Batul
Eliaba, Simon John Lubang, Gloria Habakuk Soro, Paulino Onorato Legge, Prissy M. Wai
Wai, Jackson Onan.
We also thank the course participants from Swedish Free Mission and Sudanaid for their
contributions. They are:
Inga Andersson, Margaret Toya, Isaac Kajokole Kenyi, James Jamil, James Wani, Lona Kojo
Michael, Julius Sebit, Erasto Tupa, George Mogga Wani, Elijah Biar, Rose Paul, Robert Otik,
Rhoda Yangi Wesley, Quintino Pitya, Anna Itto Njimirano, Ben Juma.
We extend our thanks also to Tom Benton, Sr. Margaret Donohue RSM, Paul McGleenan,
Paul Hiebert, Char Holcomb, Stephen Power SJ, Dr. Douglas Reitsma, Susan Sunflower, Dr.
Ruth Goehle, Betsy Bascom, for the tiresome work of proofreading.
We thank Mike Gogonya, Hakim Benjamin and Stephen Hakim for many of the drawings.
We are also very grateful to Michael Kubrom Habtai who shared his office with us during the
weeks of final revision and typing, made the SCC library available for us and encouraged us
with practical help and supporting words.
We thank the Sudan Council of Churches, and especially the Deputy General Secretary,
KostiManibe, for the generous support which made this manual possible, by providing
working facilities, financial resources, an electronic typewriter and numerous other resources.
There are many other individuals whom we would like to thank for their helpful contributions,
but who are too numerous to be named.
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We apologise for mistakes which remain in the manual inspite of revisions and corrections,
and kindly ask the readers to send any corrections, comments and suggestions about the
manual to one of the following two addresses:
Márta Guóth-Gumberger, Rudolf Gumberger
Neue Heimat 5a
D-83024 Rosenheim
Germany
Tel.: 08031/81103
Fax: 08031/43695
Munuki Water and Sanitation Project
Sudan Council of Churches
P.O. Box 469
Khartoum
Sudan
For further copies of the manual please contact:
Publicity Office
Sudan Council of Churches
P.O.Box 469
Khartoum
Sudan
Any parts of this manual may be copied, reproduced or adapted to local needs, without
permission from the authors or publisher, provided the parts reproduced are distributed free
or at cost, not for profit. For any reproduction with commercial ends, permission must be
obtained from the authors and the Sudan Council of Churches. The authors appreciate being
sent a copy of any materials in which text or illustrations have been used.
As this work would never have been possible by our own strength without God’s help, so we
hope that God will also protect and strengthen any persons who use this manual and any
future work done with the help of this manual.
Knartoum, 11.11.1987
Márta and Rudi Guóth-Gumberger
0.3 Purpose of the Manual
The following introduction should help the reader to orientate her/himself to the manual and
make best use of it.
According to the title, this manual is intended for small development projects with 20 to 40
staff members. The administrative and organisational structures described correspond to this
project size.
Secondly, this book is a training manual. It does not intend to present all the information
available for professionals about a covered topic, but rather to select the most basic and
relevant information about a topic. Then it arranges and presents it in such a way as to
introduce a beginner, but also that a trained staff can find it helpful. The manual will help
senior staff to organise and improve their management.
The aim of this manual is to train senior secondary school leavers to become skilled
technicians in water supply and sanitation work, to run a store, to keep records and do
qualified field work, or to become community development officers. They should be able to
lead a team later on and to do basic work in administration.
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However, the manual can serve different purposes as described below:
1. Training:
- It can be used by the trainee for self-study or as complementary material to the teaching
in class.
- It can be used by the teacher/instructor as a guideline for preparing lessons in class
about the covered topics.
- Some parts can be used as guideline for technical training for illiterate people.
- Some parts can be used as guideline for training sessions in the community.
2. Guideline:
- It can be used by experienced people as a help to develop and build up a new small
project.
3. Reference book:
- It can be used as reference in day-to-day project work in the different covered fields.
- It can be used by the trainee for looking up particular information after the course.
- It can be used for revising previously acquired knowledge.
0.4 Possible Readers of the Manual
The manual provides material for a two years training course for several (technical) areas with
25% training in class and 75% training in the field. It is expected that not everything in the
manual is for every trainee or reader.
The manual was developed in a water and sanitation project. Therefore, major parts deal with
these subjects. However, many parts are of a more general nature so that they might be
useful for staff of other projects, for churches, communities and development organisations.
In detail, material from the manual might be useful for the following groups of staff:
No
1
Staff or Trainees
Relevant
Sections
1,2,3,7
2
3
4
senior
staff
in
management
functions
administrative staff, typist
bookkeeper
community development staff
1,2
1,5
1,4,9
5
water supply staff
1,5,6,7,8,9
6
other technical staff like building
staff
storekeeper
logistics staff
driver
1,3,5,6,7
7
8
9
1,5,6,7
1,3,5,7
1,3,5
7
Relevant Chapters
4.18; 4.21; 5.1; 5.2;8.11 8.29;
9.8
5.1; 5.2; 5.8
2.9-18; 3.3-4; 7.2-12
2.7; 2.11-12; 2.18; 3.1; 3.2;
3.11-13; 5.1-2; 5.8 7.1; 7.6;
8.1-11; 8.29; 8.33; 8.36-39
2.11-15; 2.18; 3,1-2; 3.11-13;
4,1-2; 4,15-16;
8.32
2.18; 6,3-5
2.18; 6,3-5; 7.6
0.5 Summary of the Contents
The manual consists of nine sections, compiled in three volumes:
Volume I
ADMINISTRATION
and
COMMUNITY DEVELOPMENT
1.
2.
3.
4.
General Knowledge
Administration
Running a Vehicle
Community Development
Volume II
WATER SUPPLY
5.
6.
7.
8.
9.
Mathematics
Basic Technical Knowledge
Building Administration
Water Supply
Sanitation
Volume III
SANITATION
Volume I contains the general parts combined with community development, volume II and III
contain the technical parts.
The manual was divided into three volumes so that it can be used in parts and become more
handy for the reader. Sanitation was taken as a separate volume, because many may be
interested in this section alone. Still, the manual is one work and the different sections belong
together. There are many references pointing to other chapters in a different volume.
The different sections are briefly introduced in the following:
1. General Knowledge
Relevant information not fitting into the other sections was compiled here. “Using a
Dictionary”, “Reading Techniques” and “Study Techniques” are useful for the work with the
manual. “Private Budgeting”, “First Aid” and “Applications” are also generally needed
knowledge.
2. Administration
The basic administrative knowledge and procedures for a small project of 20 to 40 staff
members are compiled here.
3. Running a Vehicle
Here everything which a responsible user of a vehicle - not a mechanic! - has to know in order
to run the vehicle economically and to prevent unnecessary damages is compiled. The
section is important for both senior staff or logistics staff and drivers.
4. Community Development
This section compiles basic information necessary for community development work, both of
general nature and background information as well as practical procedures.
5. Mathematics
The manual is not intended to be a mathematics book. Therefore, you cannot find detailed
explanations of mathematical principles. Rather you will find a collection of mathematical
knowledge in recipe-style about whatever was found necessary for the project work - mostly
very simple things and few more sophisticated.
6. Basic Technical Knowledge
Basic technical knowledge for the water supply and sanitation work is compiled here, “Basic
8
Technical Drawing”, “Using Measuring Tools”, “Tools”, and “Cement and Concrete” being the
most important ones to be studied first.
7. Building Administration
The specific administration necessary for construction work is described her, consisting of
“Planning”, “Record Keeping”, “Cost Calculation”, “Purchasing” and “Storekeeping”.
8. Water Supply
The section about water supply starts with general knowledge about water, discusses the
different well types, the selection of a well site. Construction of hand dug wells with concrete
rings is described in detail. An overview about pump types is given; some of them are
described in more detail, especially hand pumps, and basic plumbing is added. “Well
Disinfection”, “Water Treatment” and “Health Education” are discussed in the end.
Hand dug wells and hand pumps were deliberately selected as main topics to be covered.
Other books (see bibliography No.17, 18,35) cover these topics much more comprehensively;
however, here the emphasis was to prepare training material in easily understood overviews
and step-by-step procedures.
9. Sanitation
This section starts with general background knowledge about sanitation. The different types
of disposal systems are introduced and guidelines for selecting the suitable latrine suggested.
Deliberately, only sanitation systems without water were selected to be covered. Several are
described in more detail. The main emphasis lies on compost latrines, including different
designs, composting process, construction, operation and maintenance, and follow-up.
Chapters about children’s squatting slab, bath, waste matter and pesticides complete the
section. Many parts of this section are suitable for training sessions about sanitation in the
community or in schools.
0.6 Format and Style of the Manual
As the purpose of the manual is to assist trainees, teachers and field staff, we put emphasis
on giving it a consistent and easily understandable format. The colleagues in the project work
found that providing structures was helpful, and they had no difficulties at all filling the
structures with life and flesh. Therefore, the manual offers a lot of structures, forms, tables,
boxes, and step-by-step procedures. This shall help to gain an overview about the field and to
easily find the required information.
A) Format of the Manual
The page numbers on top of each page reflect the format of the manual. Each one of the nine
main sections contains several chapters. Each chapter has one or more pages.
The introduction with foreword, etc., is added as another section 0. The appendix with
9
bibliography, index, etc., is added as section 10. Section 0 and 10 are attached to all three
volumes to help the reader use the manual. Thus, the volumes contain these sections:
Volume I
Volume II
Volume III
: sections 0,1,2,3,4,10
: sections 0,5,6,7,8,10
: sections 0,9,10
Consecutive page numbers at the bottom of each page run in each volume separately.
Each chapter starts on a new page. Both the title of the section and the chapter are named:
8. Water Supply
8.14 BASIC PLUMBING
Directly under this headline you will find one or several bible quotations in some chapters.
These were used for the prayer fellowships which were an integrated part of the three months
course, and are related to the topic where they are mentioned.
Usually, each chapter starts with a brief introduction as each chapter is an entity by itself and
should be readable by itself. The material within one chapter is mostly structured according to
the same system, for example, in the lesson “Basic Plumbing”:
A) Threads
1. Thread Types
a) Internal/External Threads
b) Right Hand/Left Hand Threads
c) .............
d) .............
e) .............
f) .............
2. Thread Standards for Bolts and Nuts
a) Metric Coarse Threads M
b) .............
c) .............
.............
3. Thread Standards for Pipes
a) .............
b) .............
.............
4. Pipe Measurements
B) Basic Operations of Plumbing
1. Cutting with a Hacksaw
2. Pipe Cutting
3. .............
C) Pipe Joints
1. .............
2. .............
.............
10
Most lessons have only a structure A, B, C, ... and 1., 2., 3., ... All titles are capitalised and
underlined, as well as other important words within the text. All important messages are put
into boxes. Step-by-step procedures are either numbered or put into a box with a separate
column giving the reasons. All tables are in boxes.
As each chapter is a separate entity and can be used as a teaching unit, a continuous flow
between the chapters is not maintained. Repetitions occur sometimes, otherwise, a reference
refers to the relevant chapter containing more information about a certain point.
B) Language of the Manual
The manual deliberately uses simple English to explain a topic, to give trainees with limited
English knowledge a chance. Simple sentence constructions were preferred to elegance of
style. Some special vocabulary in the different topics was introduced, but always with
explanations. Often another equivalent word is given in brackets, e.g.
“serrated (= toothed)”,
“aquifer (= water-bearing layer)”
As the book is a training manual, no foot-noting was applied. We used drawings and
information from books together with project experience and compiled them for the teaching
purpose. The literature used and useful for further readings is compiled in the bibliography.
C) Drawings
Many drawings are added for illustration and easy reading. In the technical part, mostly
proper technical drawings are used (such as cross-section, layout plan, etc.), because they
convey the information in a more correct and complete way than other types of drawings. The
reader/trainee not acquainted with technical drawings must study chapter 6.1 “Basic
Technical Drawing” before reading. Experience showed that the trainees without previous
technical training were soon able to read technical drawings. The drawings in the manual
shall also give the trainee practice in reading technical drawings. Almost all drawings are
placed below or beside the relevant text, although this way consumed more space. This shall
ease the reading as well.
0.7 Instructions on how to Use the Manual
As not everything in the manual is useful for each reader, you need to pick what is interesting
for you. Selection should be easy because of the provided structures. The following can help
you to make full use of the manual:
1. Do not attempt to read the manual from the first to the last page like a novel.
2. Make yourself acquainted with the format and the paging of the manual (see 0.6).
3. Cut separation taps from carton paper for the different sections and glue and staple
them to the title page of each section.
4. Use the SQ3R-method explained in 1.3 to read the manual.
5. Read the table of contents and mark which chapters are interesting for you.
6. Decide which chapters to read first. Chapters 1.2, 1.3, 1.4, 5.1, 5.2, provide necessary
basics for further reading of the manual; for technical staff also 5.3, 5.4, 6.1.
7. Apply the SQ3R-method for each chapter as well. Read the headlines of the chapter
first to get an overview, collect your questions about the material, etc.
11
8. Underline important key-words; write your notes, remarks and questions into the manual
wherever needed.
9. Use the list of abbreviations, list of forms used, list of leaflets and posters, in the end of
each volume.
10. Use the index in the end of each volume to quickly find information about a certain
point.
11. Use the bibliography for further studies.
0.8 Instructions how to Teach with the Manual
There are many books about how to teach, and teaching methods are not the topic of this
manual. Thus, only a few suggestions are compiled in the following on how to teach with this
manual (see also 4.14; 4.24).
A) General Learning Conditions
Help obtain good learning conditions:
1. Take special care that the class becomes a community, that the trainees get to know
and respect each other, that they can mutually help each other. Fruitful learning can only
take place in an atmosphere of cooperation.
2. Believe that the trainees are capable of learning. Trust is essential for encouragement
and learning.
3. Take special care that the physical situation is supportive for learning: an adequate
room, water, feeding, sanitation must be available. Involve the trainees by distributing
assignments (fetching water, cleaning, organising food, etc.).
4. Take care that the trainees have sufficient materials like files, paper, pens, etc.
5. Arrange the class in the classroom in a circle whenever possible. This is the case for
most of the chapters in this manual, except for the ones involving calculations.
B) Planning Lessons
Good preparation is essential for good teaching:
1. Take time for preparing your lessons. Roughly estimate as much time for preparation as
for class time.
2. Plan the syllabus before a training course.
12
3. Each chapter in this manual is an entity by itself and can be used as guideline for a
lesson. Some chapters may take several lessons to cover. Roughly, maximum five pages
can be covered in a teaching unit of two hours.
4. Plan extra lessons in the beginning of the course just for explaining the syllabus and the
format of the manual.
5. Plan enough time for evaluation.
6. When planning your lessons, mix the teaching methods: mix group-work with class
discussions, calculations with explanations on a model, etc.
7. Have your teaching material (models, posters, etc.) ready before the lesson.
C) Teaching Methods in Class
A variety of teaching methods is suitable for teaching with this manual in class:
1. You can structure many lessons according to the SQ3R-method (see 1.3):
S = Survey: Explain at the beginning what the lesson will cover.
Q = Question: Ask the trainees if they have questions about the topic and note these
down. Check after the lesson if the questions were answered.
R = Read: Conduct the lesson. Explain the material.
R = Recite: Let trainees repeat and explain with their own words what they have learnt
and understood.
R = Revise: Give homework, revise the following day or after one week.
2. Use group-work. Let groups of 4 to 5 discuss a certain question, try to read a passage
or a drawing of the manual together, collect different aspects of a topic, etc.
3. Use discussion in the whole class to summarize group-work, to intro duce something
new, to explain an aspect relevant to all.
4. Use from time to time work on a certain assignment for each trainee alone (e.g.
calculations).
5. Use role plays whenever possible (e.g first aid, interaction of technicians with the
community, etc.). They are fun and very educative.
6. Teach by action whenever possible (e.g. cleaning and rehabilitating a latrine, safety
measures, interview, etc.).
7. Include field visits into your training programme.
8. Use posters, models, actual examples, whenever possible. Many of the drawings in the
manual can be drawn on big posters for use in class. Well construction work is best
understood when demonstrated with small models. Bring pieces of material for everything
you discuss in class.
D) Questions
Asking questions is a way to learn, for both the teacher and the trainee.
1. Encourage the trainees to ask questions.
13
2. Ask at the end of a lesson whether there are any questions.
3. Ask in the beginning of a lesson if questions remain from the day before.
4. If you cannot answer a question, do not pretend and dodge around. Admit it, look it up
after the lesson, and answer it the next day.
5. Spend some time before and after the lesson in class to give the trainees a chance to
ask.
E) Homework
Study on her/his own is essential for the trainee in order to be able to digest the material
learnt.
1. Give homework to almost all of your lessons.
2. Encourage students to keep their homework well filed and organised with chapter
numbers and headlines.
3. Ask trainees from time to time to prepare for a lesson on their own by studying the
manual in advance.
4. Take time to correct the homework and return it as soon as possible.
F) Teaching Field Work
Some extra efforts in teaching field work will improve the results considerably.
1. Before you do a new type of work the first time in the field (like lowering concrete rings
into a well), discuss the step-by-step procedures in detail in class. Use a model to illustrate
the steps. This will help the trainees to keep an overview of the work. It will also help them
see themselves as a part of the whole team and process rather than individuals doing just
menial work. Discussion beforehand in class is better than trying to explain on the spot in
the hot sun when half of the staff cannot hear you.
2. Sit down in the shade with the staff after having completed a new job or after something
has gone wrong. Evaluate what happened by asking: What did you learn? What was new?
What went wrong? What could be done better?, etc. (see also 2.7). This can help a lot how
to judge the situation and how to improve techniques.
3. The same methods can be applied when teaching field work to illiterate people. Using
models is even more important.
14
5. Mathematics
5.1 Basic Calculations
The most basic rules for calculations are compiled here for the everyday project work.
A) Decimals
Money, measurements (not time!) are expressed in decimals. All the figures to the left of the
decimal point are whole numbers - units, tens, hundreds, thousands etc. All those to the right
are fractional parts - tenths, hundredths, thousandths etc.
15
No matter how many figures come after the decimal point, they amount to less than one unit.
0.78925 is less than one.
The figures to the right of the decimal point are called “decimal places”. For example, 4.06
has 2 decimal places.
B) Addition and Subtraction of Decimals
Adding and subtracting decimals is just the same as adding and subtracting whole numbers.
- The sums must be set down in an orderly way.
- Keep the units, tens, hundreds, etc., in their correct columns.
- Keep the tenths, hundredths, thousandths, etc., in their correct columns.
- Keep the decimal points in a vertical straight line.
- A whole number like 15 may be written 15.00 to keep it more easily in the correct columns.
Putting the decimal point and adding a convenient number of zeros (= noughts = 0) after it
does not alter the amount.
- Start the work on the column farthest to the right of the decimal point. Carry tens in the
ordinary way, as if the decimal point was not there.
- Put the decimal point in the answer under the decimal points above.
- Using checkered paper can help to avoid mistakes.
Example:
C) Multiplication and Division of Decimals
The most frequent cause of mistakes in multiplication and division of decimals is putting the
point in the wrong place. There are simple rules for placing the point correctly.
16
1. Multiplication of Decimals by 10, 100, 1000, etc.
- To multiply a decimal number by 10, simply move the point one place to the right.
- To multiply by 100, move the point two places to the right.
- To multiply by 1000, move the point three places to the right.
- Add extra zeros (= noughts), if necessary.
Examples:
2. Division of a Decimal by 10, 100, 1000, etc.
- To divide a decimal number by 10, move the point one place to the left.
- To divide by 100, move the point two places to the left.
- To divide by 1000, move the point three places to the left.
- Add extra zeros (= noughts),if necessary.
Examples:
The decimal point is moved one place left for each zero in the divisor:
3. Multiplication of a Decimal with a Whole Number
- Work like for ordinary multiplication sum.
- Start at the far right of the decimal point.
- Keep the figures and the decimal points in their correct columns.
- Check that you have the same number of decimal places in the answer as you have in the
numbers you are multiplying.
Example:
Multiply 468.25 by 3
17
468.25
3
1404.75
4. Multiplication of a Decimal Number by Another Decimal Number
- Ignore the decimal points while you multiply.
- Count how many decimal places there are altogether in the two numbers you have
multiplied.
- Count that number of places from the right in the answer, and put in the point.
Example:
5. Division of a Decimal Number by a Whole Number
- Work like for an ordinary division.
- Keep the figures and the decimal points in their correct columns.
- Extra zeros may be added after the decimal figures of the dividend.
- You will sometimes be able to get an exact answer, but sometimes you may only work to
two or three decimal places.
Example:
Divide 26.1 (= dividend) by 6 (= divisor)
6. Division of a Decimal Number by a Decimal Number
18
- First turn the divisor into a whole number by moving the decimal point the necessary number
of places to the right.
- Move the decimal point of the dividend the same number of places in the same direction. (If
you multiply the dividend and the divisor by the same amount, the answer will still be the
same:
Example:
30 300
=
= 3)
10 100
- Then work out the division in the ordinary way.
Example:
Divide 2.367 (= dividend) by 0.46 (= divisor)
D) Rounding Up and Down
When looking for the nearest whole number:
- Ignore anything less than half.
- Count half or more as another whole number.
Examples:
357.1 → 357
357.4 → 357
357.5 → 358
357.9 → 358
When looking for a certain number of decimal places:
- Look at the following decimal place.
- If the last figure is less than 5, ignore it.
- If it is 5 or more, add 1 to the previous figure.
Examples:
4.213 → 4.21
4.214 → 4.21
19
4.215 → 4.2 2
4.219 → 4.2 2
4.295 → 4.3 0
E) Avoiding Mistakes
Keep to the following discipline to avoid mistakes:
- Always use enough space for calculations. Squeezing them onto a small piece of paper
leads to mistakes.
- Always write clearly.
- Calculate each addition and subtraction twice before you proceed to use the answer. This
will help avoid wasting time searching for mistakes later on.
- Don’t let yourself get a ridiculous answer! Before you work out a problem in detail, you can
make a rough estimate of what the answer should be. If your answer is very different, you will
know you have made a mistake. A rough estimate is not a guess. You simplify the figures so
that you know the answer cannot be more than a certain amount, or less than a certain
amount. Therefore, the right answer must lie between them.
Examples:
5.2 Percent Calculations
“Per cent” (= %) means “out of each hundred”.
“ % “ can be replaced by “ ×
1
“ or by “ × 0.01 “.
100
The percentage is a certain part of a whole. % indicates the proportion of the part to the
whole. For comparison 100 is used as a convenient standard.
Example:
5% = 5 ×
1
5
1
=
=
= 0.05; or conversion back :
100 100 20
1
= 0.05 = 0.05 × 100% = 5%
20
A) Equivalents
The size of each part of a whole can be expressed in four different ways. Watch out for these
equivalents:
No.
1.
2.
3.
Expression
in words
as a fraction
as a decimal
Conversion
fraction × 100 → %
decimal × 100 → %
20
4.
as a percentage of the whole
% ÷ 100 → fraction or decimal
Parts of a whole
B) Basic Operations
There are two basic operations:
1. Operation
Calculate a certain percentage of a given number (= whole).
To find the percentage of a given number, write the percentage as a fraction (with the
denominator 100) and multiply it by the number. Simplify by cancelling, if possible.
part =
percentage
× whole
100
Example 1:
Your salary of £S 120.000 shall be raised by 157% at the beginning of the year. What will be
your new salary?
given:
asked:
15% of £S 120
old salary
15% increase
new salary
salary £S 120 = 100% (= whole)
15% of £S 120 =? (= part)
=
15
× £S 120 = £S 18
100
£S 120
£S 18
£S 138
Example 2:
The costs estimated for a double compost latrine of a school are £S 9500. 5% shall be added
for supervision and depreciation of equipment. How much will be the total costs?
given:
building costs £S 9500 = 100% (= whole)
21
asked:
5% of £S 9500
5% of £S 9500 =? (= part)
=
5
× £S 9500 = £S 475
100
building costs
5% supervision
total costs
£S 9500
£S 475
£S 9975
2. Operation
Calculate what percentage one number (=part) is of another number (=whole).
In order to find what percentage one number (= part) is of another number (= whole), we
divide the part by the whole and multiply by 100. Thus you obtain a result in %.
percentage of a part of a whole =
part
× 100
whole
Example 1:
During one month the project car was driven 255 km for CD-department, 510 km for WSdepartment and 315 km for Administration, total 1080 km. How many % did each department
drive?
given:
asked:
total 1080 km
255 km (=part)
510 km (=part)
315 km (=part)
CD:
255 km
× 100
1080 km
510 km
× 100
1080 km
315 km
× 100
1080 km
WS:
Adm.:
= 100% (= whole)
=? % of 1080 km
=? % of 1080 km
=? % of 1080 km
= 23.6%
= 47.2%
= 29.2 %
100.0%
(Check if the sum of all percentages is 100%!!)
Example 2:
The total costs of a well were £S 8700. £S 3900 were contributed by the community, £S 4800
by the project. How many % did the community contribute, and how many % the project?
given:
asked:
total costs £S 8700
£S 3900 (= part)
£S 4800 (= part)
community:
£S 3900
× 100
£S 8700
£S 4800
× 100
£S 8700
project:
= 100% (= whole)
=? % of £S 8700
=? % of £S 8700
= 44.8%
= 55.2%
100.0%
5.3 Measurements
The most important and common measurements for water supply work are compiled here in
22
transformation tables.
A) Measurements for Distances in Metric System
mm
If you want to
change these
units:
mm
cm
dm
m
km
to these:
dm
÷ 100
cm
÷ 10
× 10
× 100
× 1,000
× 1,000,000
÷ 10
× 10
× 100
× 100,000
× 10
× 10,000
m
÷ 1,000
km
÷ 1,000,000
÷ 100
÷ 10
÷ 100,000
÷ 10,000
÷ 1,000
× 1,000
mm = millimetre
cm = centimetre
dm = decimetre
m = metre
km = kilometre
Using transformation tables you can change from one unit to another. Use them as follows:
Example:
435 m =? km
You want to transform the unit “m” to “km”. Look in the left column for “m” and along the top
row for “km”. You find the necessary operation for transformation where the column of “km”
meets the row of “m”: ÷ 1,000
Therefore divide 435 by 1,000.
435 m = (435 ÷ 1,000) km = 0.435 km
B) Measurements for Distances in English System
1/16 “
If you want to change
these units:
1 “
16
“
‘
yd
mile
“
÷ 16
× 16
× 192
× 576
× 1,013,760
1/16 “ = one sixteenths inch
“ = inch
‘ = foot
yd = yard
mile = mile
23
to these:
‘
÷ 192
÷ 12
× 12
× 36
× 63,360
×3
× 5,280
yd
÷ 576
mile
÷ 1,013,760
÷ 36
÷3
÷ 63,360
÷ 5,280
÷ 1,760
× 1,760
C) Measurements for Distances: Transformations between Metric and English System
cm
If you
want to
change
these
units:
cm
‘‘
‘
yd
m
km
mile
× 2.54
× 30.48
× 91.44
× 100
“
÷ 2.54
‘
÷ 30.48
÷ 12
× 12
× 36
× 39.37
×3
× 3.2808
to these:
yd
÷ 91.44
÷ 36
÷3
m
÷ 100
D) Measurements for Areas in Metric System
24
mile
÷ 1,000
÷ 1,609
÷ 1.609
÷ 39.37
÷ 3.28
÷ 1.09
× 1.0936
× 1,000
× 1,609
cm = centimetre
“ = inch
‘ = foot
yd = yard
m = metre
km = kilometre
mile = statute mile
km
× 1.609
2
If you want to change these units:
to these:
dm2
÷ 100
cm2
cm
dm2
m2
× 100
× 10,000
m2
÷ 10,000
÷ 100
× 100
cm2 = square centimetre
dm2 = square decimetre
m2 = square metre
E) Measurements of Volumes
If
you
want to
change
these
units:
3
cm3 = ml
cm
dm3
gal
drum
m3
to these:
gal
÷ 4,550
dm3 = lit
÷ 1,000
× 1,000
× 4,550
× 220,000
× 1,000,000
÷ 4.55
× 4.55
× 220
× 1,000
× 48.4
× 220
drum
÷ 220,000
m3
÷ 1,000,000
÷ 220
÷ 48.4
÷ 1,000
÷ 220
÷ 4.55
× 4.55
cm3 = cubic centimetre = ml = millilitre
dm3 = cubic decimetre = l = lit = litre
gal = gallon (imperial)
drum = drum
m3 = cubic metre
For transformation of measurements of pumping rates (= yields = discharge = volume/time)
see 8.34/1.
F) Measurements for Time
sec
If you want to change these units:
sec
min
h
days
× 60
× 3,600
× 86,400
to these:
min
h
÷ 60
÷ 3,600
÷ 60
× 60
× 1,440
× 24
days
÷ 86,400
÷ 1,440
÷ 24
sec = second
min = minute
h = hour
days = days
G) Measurements for Weights
to these:
g
kg
÷ 1,000
÷ 1,000,000
mg
If you
change
units:
want to
these
mg
g
kg
t
× 1,000
× 1,000,000
× 1,000,000,000
25
÷ 1,000
× 1,000
× 1,000,000
× 1,000
t
÷ 1,000,000,000
÷ 1,000,000
÷ 1,000
mg = milligram
g = gram
kg = kilogram
t = tonne = metric ton
H) Measurements for Temperatures
Conversion formulas:
°F =
°F = degree Fahrenheit
9
°C + 32
5
°C = (°F - 32) ×
5
9
°C = degree Celsius
Conversion table (approximate):
°C
-18
-10
0
10
20
30
40
50
60
70
80
90
100
°F
0
10
20
30
32
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
212
°F
0
14
32
50
68
86
104
122
140
158
176
194
212
°C
- 17.8
- 12.2
- 6.7
- 1.1
0
4.4
10
15.6
21.1
26.7
32.2
37.8
43.3
48.9
54.4
60
65.6
71.1
76.7
82.2
87.8
93.3
98.9
100
26
Conversion scale:
5.4 Basic Geometry
The most basic terms and definitions of geometry necessary for technical work are compiled
here:
A) Point
or
A point is a very small area. For example the crossing of 2 straight lines is a point.
B) Straight Line
A straight line is indefinitely long and indefinitely thin. Any 3 points on the line mark a 180°
angle. Two points define a straight line. A straight line is the shortest distance between 2
points.
Examples for straight lines:
- the edge of a table
- a measuring tape
- the string of a plumb bob
C) Plane
A plane is indefinitely long and broad and indefinitely thin. Straight lines can be fitted into the
plane in any direction. Three points define a plane.
Examples for planes:
- a piece of paper
- the straight surface of a table
27
- the surface of a lake
D) Angle
An angle is formed between two intersecting lines.
The angle between the lines AB and BC is called <ABC.
<ABC is the rotation required to turn the line AB on to the line BC: the centre of the rotation is
point B.
If AB is rotated about point B, each point on the line describes a circle. An angle is measured
in degrees.
The complete rotation is 360°.
One degree is
1
of a complete rotation.
360
Examples for angles:
- the angles between trusses of a roof
¾ of a complete rotation is 270°.
28
½ of a complete rotation is 180°.
¼ of a complete rotation is 90°; this is known as “right angle”.
Examples for right angles:
- the corner of a table
- the corner of a window
- the corner of a house
- the corner of a sheet of paper
29
- the corner of a latrine slab
E) Parallel Lines
Parallel lines are lines which never meet. They always remain the same distance apart, no matter
how far they are extended.
Examples for paralles lines:
- two opposite sides of a table
- two opposite edges of sawn timber
- two opposite edges of a sheet of paper
- railway tracks
- two legs of a ladder
F) Symmetry about an Axis
Shapes in a plane are symmetric about an axis (= straight line) if folded about that axis, one half
can be superimposed on the other. Each part has a corresponding part the same distance from
the axis of symmetry.
Examples for symmetry about an axis:
- a sheet of paper
- a rectangle
- a circle
- a blackboard
- the surface of a table
Symmetry of 2 Points A and B
30
Symmetry of 2 Parallel Lines
Symmetry of 2 Parallel Lines
Symmetry of Square
Symmetry of Square
31
Symmetry of Rectangle
Symmetry of Rectangle
Symmetry of Circle
Symmetry of Equilateral Triangle
32
Symmetry of 2 Triangles
Symmetry of 2 Irregular Shapes
G) Symmetry about a Plane
3- dimensional solids are symmetric about a plane if each part has a corresponding part the
same distance from the plane of symmetry. That means that they can be divided (= cut) into
two equal, exactly similar parts.
Examples for symmetry about a plane:
- rectangular solids
- cylinder
- screwdriver
- hammer
- shovel
- pipe
- fruits like papaya
H) Rotational Symmetry about an Axis
33
3-dimensional rotational symmetric shapes can be produced by rotating any plane shape
around an axis. They can be turned around their axis and always look the same.
Rotational symmetric items are symmetric about any plane through the axis (that are
indefinitely many planes of symmetry). Any plane vertical to the axis cuts the rotational
symmetric shape in a circle.
Examples for rotational symmetry:
- pipes
- wooden items produced by lathing
- clay pots produced on a potter’s wheel
- bowls
- bottles
- nails
- concrete rings
- tyres
I) Triangle
Three points connected with straight lines form a triangle.
34
Area:
Perimeter:
A=
1
hc
2
P=a+b+c
J) Quadrilateral
Four points connected with straight lines form a quadrilateral. It is also called polygon of 4
sides.
K) Parallelogram
A parallelogram is a quadrilateral with both pairs of opposite sides parallel and equal in
length.
Connections:
Area:
Perimeter:
a || c
b || d
a=c
b=d
A=ah
P = 2(a+b) = 2(c+d)
L) Rectangle
A rectangle is a parallelogram with right angles. A rectangle is symmetric about 2 axis. The
diagonal is the connection of two opposite corners by a straight line.
35
Connections:
Area:
Perimeter:
Diagonal:
all four angles: 90°
A=ab
P = 2(a+b)
c = a2 + b2
Examples for rectangles:
- sheet of paper
- blackboard
- door
- latrine slabs
M) Square
A square is a rectangle with all sides equal. A square is symmetric about 4 axis.
36
Area:
Perimeter:
Diagonal:
A = a2
P=4a
c = 2 a2
Examples for squares:
- childrens’ squatting slab
- manhole in well cover
N) Circle
Points in a plane with the same distance from a fixed point form the circumference of a circle.
The fixed point is called the centre of the circle, the constant distance the radius. A straight
line through the centre is called the diameter.
A circle is symmetric about all straight lines through the centre.
Radius:
Diameter:
Circumference:
Area:
r=
d
2
d=2r
C=2πr
A = πr2 =
1
π d2
4
π = 3.14
37
0) Hollow Circle
Two circles with the same centre form a hollow circle.
A hollow circle is symmetric about all straight lines through the centre.
Inside radius:
Outside radius:
Inside Diameter:
Outside Diameter:
Area:
r
R
d
D
A
= π (R2 - r2)
=
1
π (D2 - d2 )
4
= π (R + r)(R- r)
Examples for hollow circles:
- washers
- rubber seatings
P) Cylinder
A rectangle rotating around its axis forms a cylinder. A cylinder has the same circle as base
and top. A cylinder is rotational symmetric.
Radius:
Diameter:
Height or length:
Volumes:
Total surface area:
r
d=2r
h or l
V = π r2 h
SA = 2 π r h + 2 π r2
38
Examples for cylinders:
- reinforcement rod
- tins
- poles
- axles
Q) Hollow Cylinder
Two cylinders with the same centre form a hollow cylinder. A hollow cylinder is rotational
symmetric.
Inside radius:
Outside radius:
Inside diameter:
Outside diameter:
Height or length:
Volume:
r
R
d (= ID)
D (= OD)
h or l
V = π (R2 - r2) h
39
Examples for hollow cylinders:
- pipes
- concrete rings
R) Rectangular Solid (= Cuboid)
A rectangular solid is a solid confined by 6 rectangles. It is symmetric about 3 planes.
Volume:
Total surface area:
V=abc
SA = 2(ab+ac+cb)
Examples for rectangular solids:
- sawn timber
- box
S) Cube
A cube is a special case of a cuboid. All its sides are equal.
40
Volume:
Total surface area:
V= l3
SA = 6 l 2
T) Sphere (= Ball)
A sphere is a 3-dimensional body. All its points have the same distance from a fixed point
which is the centre. It is rotational symmetric about any axis through the centre.
Volume:
V=
Surface area:
4
π R3
3
SA = 4 π R2
Examples for spheres:
- ball
- ball bearings
5.5 Calculation of Diagonal
For marking a rectangular layout plan (rectangle), we need to know the diagonal. It can be
calculated in the following way:
given:
asked:
2 sides of a rectangle, a and b
diagonal c
According to Pythagoras theorem, in a right angled triangle the square on the hypotenuse (=
longest side) is equal to the sum of the squares on the two other sides.
41
a 2 + b2 = c 2
Steps of Calculation
1. Calculate a2.
2. Calculate b2.
3. Add up a2 + b2.
4. Estimate c. Calculate c2. Compare c2 with a2 + b2.
5. Make a new and better estimation for c. Calculate c2. Compare c2 with a2 + b2.
6. Repeat step No.5 until you have a value for c exact enough.
Draw the rectangle and check if the calculated value for c is correct.
Alternatively, you can calculate c = a 2 + b2 .
Example:
given:
asked
rectangle with the sides 2.30 m and 3.50 m
diagonal
42
5.6 Calculation of Volumes
The volume of a solid is the amount of space it occupies. It can be expressed in cm3, dm3 = lit
= litre, gal = gallon, drum or m3. The transformation table for changing these units is found at
5.3/4.
The volume of a rectangular solid (= cuboid) and of a cylinder and of a hollow cylinder (=
tube) are the three most important ones for technical purposes (see also 5.4/9-10). Their
calculation is shown here with examples.
A) Volume of a Rectangular Solid (= Cuboid)
volume of a cuboid = length × breadth × height
V= l×b×h
Take care to multiply only figures with the same units!
Example:
A water tank is 1.50 m long and 1.20 m broad and 80 cm high. How much water can it hold?
given:
asked:
h
V= l ×b×h
l = 1.50 m, b = 1.20 m, h = 80 cm
volume
= 80 cm = 0.80 m
(The units of length are not the same, therefore we have to change them.)
= 1.50 m × 1.20 m × 0.80 m =
= 1.44 m3
= 1.44 × 1,000 lit
= 1,440 lit
= 316.5 gal (for transformation see 5.3/4)
1440
gal
=
4.55
1440
drums
=
220
= 6.55 drums (for transformation see 5.3/4)
B) Volume of a Cylinder
volume of a cylinder = π × (radius)2 × height
V= π × r2 × h
π = 3.14
43
Example:
The inside diameter of a concrete ring is 1.20 m, the height is 92 cm. How much water can be
stored inside the concrete ring?
given:
asked:
h
r=d÷2
V = π × r2 × h
d = 1.20 m, h = 92 cm
volume
= 92 cm = 0.92 m
= 1.20 m ÷ 2 = 0.60 m
= 3.14 × (0.60 m)2 × 0.92 m
= 1.0399 × 1,000 lit
1040
gal
4.55
1040
=
drums
220
=
= 1.0399 m3
= 1040 lit
= 228.5 gal (for transformation see 5.3/4)
= 4.7 drums (for transformation see 5.3/4)
C) Volume of a Hollow Cylinder (= Tube)
volume of a hollow cylinder = π × [(outside radius)2 - (inside radius)2] × height
V= π × [R2 - r2] × h
Example:
The outside diameter of a concrete ring is 1.40 m, the inside diameter 1.20 m, the height is 92
cm. How many liters of concrete are needed to cast this ring?
given:
asked:
h
R=D÷2
r=d÷2
V = π × [R2-r2] × h
D = 1.40 m, d = 1.20 m, h = 92 cm
volume
= 92 cm = 0.92 m
= 1.40 m ÷ 2 = 0.70 m
= 1.20 m ÷ 2 = 0.60 m
= 3.14 × [(0.70 m)2 - (0.60 m)2] × 0.92 m =
= 3.14 × [0.49 - 0.36] × 0.92 = 0.3755 m3 = 375.5 lit
44
5.7 Calculation of Weights
It is important to learn to calculate the weight of simple items like concrete rings, timber,
water, etc., in order to know if they can be lifted by the available equipment or by the number
of people present and transported by the available car.
The weight of a homogenous item (= an item consisting of one material throughout) is
calculated as follows:
weight
W [kg]
W [t]
= density
= d [kg/dm3]
= d [t/m3]
× volume
× V [dm3]
× V [m3]
The density is the weight of one dm3 (=1 lit = one litre) of a certain material.
It can be expressed in kg/dm3 or t/m3. You must multiply the unit of density by the appropriate
unit of volume, e.g. kg/dm3 × dm3 or t/m3 × m3.
The most important densities are (in approximate values):
steel
concrete
water
timber, hardwood
timber, softwood
8
2.5
1
0.7
0.55
[kg/dm3 = t/m3]
[kg/dm3 = t/m3]
[kg/dm3 = t/m3]
[kg/dm3 = t/m3]
[kg/dm3 = t/m3]
Any item floating on water has a density smaller than 1, any item which sinks in water has a
density bigger than 1.
Example 1:
How heavy is the concrete ring of chapter 5.6?
given:
asked:
V = 0.3755 m3 = 375.5 dm3 = 375.5 lit
weight
W = d × V =2.5 kg/dm3 × 375.5 dm3 = 938.8 kg
or:
W = d × V =2.5 t/m3 × 0.3755 m3 = 0.9388 t
Example 2:
Sawn timber from hardwood is loaded on a lorry in a pile 2.50 m broad, 4.50 m long and 1 m
high. How heavy is the load?
given:
asked:
rectangular solid from hardwood,
l = 4.50 m, b = 2.50 m, h = 1 m
weight
V= l ×b×h
W=d×V
= 4.50 m × 2.50 m × 1 m = 11.25 m3
= 0.7 t/m3 × 11.25 m3 = 7.88 t = 7880 kg
This weight needs to be compared with the loading capacity of the lorry. See also 3.13/1.
45
5.8 Calculation of Time
A) Indication of Time
We start to count the hours of a day at midnight. According to the British way we count the
hours from 0.00 to 12.00 which is midday. These hours are marked with a.m. which stands for
the latin words “ante meridiem” and means “before noon”. After midday the hours are counted
from 1.00 to 12.00 which is midnight. These hours are marked with p.m. which stands for
“post meridiem” and means “after noon”.
According to the international way the hours are counted from midnight 0.00 to midnight 24.00
in one go.
International Time Indication
0.00
1.00
2.00
.
.
.
12.00
13.00
14.00
15.00
.
.
.
23.00
24.00=0.00
British Time Indication
0.00 a.m.
1.00 a.m.
2.00 a.m.
.
.
.
12.00 a.m.
1.00 p.m.
2.00 p.m.
3.00 p.m.
.
.
.
11.00 p.m.
12.00 p.m.
The same indication on the clock can mean two different times and can be expressed in
different ways:
No.
1.
2.
3.
Type
international
Expression
on the clock
on a digital watch
in figures with
point
46
1. Possibility
2. Possibility
09 30
9.30
21 30
21.30
No.
4.
9.
Expression
in figures with
dash
in words
in words
in figures with
point
in figures with
dash
in words
10.
in words
5.
6.
7.
Type
british
8.
1. Possibility
930
2. Possibility
2130
nine thirty
half past nine
9.30 a.m.
twenty-one thirty
half past twenty-one
9.30 p.m.
930 a.m.
930 p.m.
half past nine in the
morning
nine thirty in the
morning
half past nine in the
evening
nine thirty in the evening
Full hours can also be expressed like 11 o’clock.
B) Calculation of Periods
Remember:
Indications of time like 9.30 are not decimal numbers!
because an hour has 60 minutes and not 100 hundredth (=
100
).
100
When calculating a period of time:
1. Count the minutes from the starting time to the next full hour.
2. Then count the hours to the full hour before the ending time.
3. Then count the remaining minutes.
4. Add upp the times.
Example:
starting time
ending time
60 min
13 o’clock
48 min
4 hours
= 4 hours
= 4 hours
= 4 hours
= 5 hours
- 35 min
- 9 o’clock
- 0 min
+ (25 + 48) min =
+ 73 min =
+ 60 min
+ 1 hour
+ 13 min
8.35
13.48
= 25 min
= 4 hours
= 48 min
+ 13 min =
+13 min =
47
6. Basic Technical Knowledge
6.1 Basic Technical Drawing
The most basic features of technical drawing are explained in this chapter. Knowledge of
these features is necessary in order to enable the technicians to read drawings and manuals.
When reading technical drawings, try to identify each line with the corresponding detail on the
object. When studying technical drawings, use models or simple objects like a matchbox, a
box or a tin, to clarify and to understand the different views. To be able to read technical
drawings, you must practise drawing yourself. Practise by drawing objects around you: tools,
furniture, houses, wells, latrines. Ask somebody experienced to correct your drawings.
A) Overview of the Different Views
This chapter will explain the following views:
- isometric view,
- cross-section,
- layout plan (= plan),
- front-view (= front elevation),
- side-view (= side elevation),
- exploded diagram, side-view,
- exploded diagram, isometric view,
- cut-away view with hidden inside details.
48
One view alone does not show the complete information about all details of the object. At
least two different views, normally three, sometimes more are necessary to describe all
details.
The arrows in the following drawing show from what angle you have to look at a building to
obtain the different views. They are explained in the following sections, supplemented by
conventions for technical drawing and technical signs.
B) Isometric View
The isometric view shows a view comparable to what can be seen with the eye if you look at
the object from a particular angle; it resembles what a photograph shows. This way of
drawing is used to clarify what the object looks like, but it is not used for plans.
Lines which are parallel in reality also appear parallel in the isometric view (e.g. the sides of
the cube). The angles shown in the isometric view are not the same as the angles in reality
(e.g. the angles between the sides of the cube are not right angles in the isometric view).
49
ISOMETRIC VIEW
C) Cross-Section A-A
In a cross-section drawing, the object is cut by a plane, usually through windows, into two
parts. You look orthogonally to the cutting plane (= vertical to the cutting plane = from the
side) and draw what you can see. This is called a cross-section A-A as shown below. A thick
chain, with arrows, marked A-A, in the layout plan (see 6.1/5) shows how the building is “cut”
to obtain the cross-section A-A. The chain (interrupted at the drawing) shows haw to cut, the
arrows show in which direction to look, the letters near the tip of the arrows indicate the
“name” of the view:
ISOMETRIC VIEW of the whole part
ISOMETRIC VIEW of the remaining part; this is not called “cross-section”!!!
50
CROSS-SECTION A-A
Scale 1:50
The cut parts are drawn with thick lines and are hatched. The dimensions are given outside
the cross-section.
In a cross-section, the planes orthogonal (= vertical) to the cutting plane “disappear” and are
shown as lines. For example, you see the floor as a line.
All angles, especially right angles, in a cross-section appear as they are in reality. The thick
chain with arrows, marked C-C, shows how the building is “cut” to obtain the layout plan C-C
(see 6.1/5).
D) Cross-Section B-B
The building can be cut also in the other direction, parallel to the short side. A thick chain with
arrows, marked B-B, in the layout plan (see 6.1/5) shows how the building is “cut” to obtain
this cross-section. This cross-section B-B is differentiated from the previous one by the capital
letters (B-B instead of A-A).
51
CROSS-SECTION B-B
SCALE 1:50
E) Layout Plan C-C (= Plan C-C)
The layout plan is a horizontal “cross-section” (e.g. a house built half way, up to the bottomhalf of the windows). You look orthogonally to the cutting plane (= vertically to the cutting
plane = from above) and draw what you can see. A thick chain with arrows, marked C-C, in
the cross-section shows how the building is “cut” to obtain the layout plan C-C (see 6.1/3).
ISOMETRIC VIEW of the whole object
52
ISOMETRIC VIEW of the bootom half; this is not called “layout plan”!!!
LAYOUT PLAN C-C
Scale 1:50
The dimensions are given beside the layout plan. In a layout plan, the planes orthogonal to
the cutting plane “disappear” and are shown as lines, e.g. all vertical walls. All angles,
especially right angles, in a layout plan appear as they are in reality.
The thick chain with arrows, marked A-A, shows how the building is “cut” to obtain the crosssection A-A. The thick chain D-D shows how to obtain the front-view D-D. The views B-B and
53
E-E are indicated in the same way. For some objects it does not make sense to cut them for
obtaining the layout plan. In this case, the layout plan is an orthogonal view from above
(examples see 6.1/10-15, 17, 18).
F) Front-View D-D (= Front Elevation D-D)
The front-view is an orthogonal view of the object without cutting. A thick chain with arrows,
marked D-D in the layout plan (see 6.1/5) shows how to look at the building to obtain the
front-view D-D. Hidden lines are sharp edges within the object, but they cannot be seen from
outside. They can be shown by dashes. However, avoid showing too many hidden details for
the sake of clarity.
FRONT-VIEW D-D
Scale 1:50
The dimensions are given beside the front-view.
In a front-view, the planes orthogonal to the cutting plane “disappear” and are shown as lines
(e.g. the outside wall on the short side of the building).
All angles, especially right angles, in a front-view appear as they are in reality.
G) Side-view E-E (= Side Elevation E-E)
The side-view is an orthogonal view of the object without cutting, similar to the front-view. You
have to decide which of them to call front-view and which side-view. Usually, the view at the
longer side of the building is called front-view.
A thick chain with arrows, marked E-E in the layout plan (see 6.1/5) shows how to look at the
building to obtain the side-view E-E. Hidden lines can be shown with dashes.
54
SIDE-VIEW E-E
SCALE 1:50
H) Variation of Cross-Section
If the location of windows, etc. makes it necessary, the object can be “cut” in two different
places. A thick chain with arrows, marked F-F, shows where the building is “cut” to obtain the
cross-section F-F.
LAYOUT PLAN C-C
55
CROSS SECTION F-F
SCALE 1:50
I) Arranging Different Views on a Plan
If a plan is big enough to accomodate several views, they are arranged exactly above and
beside each other (see the thin lines! = projection lines) and on one sheet.
Scale 1:100
Front- and side-views are arranged like this:
56
Projection lines connect the different views and show that the different parts of the object
have the same width or height in the different views- They are a help while drawing, but
normally do not show up in the final picture; here they are added for illustration.
Scale 1:100
If not all views are to be drawn, a different combination of views can be arranged on the
sheet.
J) Examples of the Different Views
Several objects are shown in the following in the different views for illustration of the drawing
principles (for mere examples see especially 7.10/5; 8.14; 8.18; 8.19; 8.30; 9.14 and many
others);
1. Cylinder
ISOMETRIC VIEW
57
FRONT-VIEW A-A
SIDE-VIEW B-B
CROSS-SECTION C-C
LAYOUT PLAN D-D
58
4. Concrete Ring
ISOMETRIC VIEW of object
ISOMETRIC VIEW of half
SIDE-VIEW A-A
59
CROSS-SECTION B-B
LAYOUT PLAN C-C
2. Two Cuboids
ISOMETRIC VIEW
60
3. Two Cuboids with Cut-Out
61
ISOMETRIC VIEW
62
63
5. Diverse Steel Profiles
What do the different profiles look like in a layout plan D-D?
64
6. Ball
SIDE-VIEW
CROSS-SECTION
7. Bolt and Nut and Washer
SIDE-VIEW A-A
65
CROSS-SECTION B-B
LAYOUT PLAN C-C
SIDE-VIEW A-A in different way
8. Reinforced Beam
66
SIDE-VIEW A-A (1:40)
CROSS-SECTION B-B (1:10)
The cross-section is not hatched in order to show the reinforcement clearly.
LAYOUT PLAN C-C (1:40)
67
REINFORCEMENT (1:10)
9 Ø 6 stands for 9 pieces reinforcement, diameter 6 mm.
2 Ø 10 stands for 2 pieces reinforcement, diameter 10 mm.
K) Drawing of Rotational Symmetric Parts
For rotational symmetric parts side-view and cross-section are often united in one drawing,
taking half of each. This saves drawing work and space, but still provides complete
information. See the following examples.
1. Bolt and Nut and Washer (compare with 6.1/17)
The nut itself is not rotational symmetric but still can be drawn like this, because it is clear
what a nut looks like.
2. Concrete Ring (compare with 6.1/11)
68
3. Pump Piston
ISOMETRIC VIEW
69
L) Exploded Diagram
Exploded diagrams are mainly used in installation manuals and spare part drawings of pumps
and other machinery. They show exactly how parts, bolts, nuts and washers have to be
assembled. All the parts are drawn as if moved apart by an “explosion”. Thus each part can
be clearly seen.
Thin, long chains ______________________ indicate where the part needs to be attached.
Exploded diagrams can be drawn as side-views or as isometric views.
1. Exploded Diagram - Side-View (Part of Diaphragm Pump)
70
2. Exploded Diagram - Isometric View (Parts of Transportable Generator)
M) Cut-Away View with Hidden Inside Details
Sometimes the outside view of an object (side-view or isometric view) is used to show hidden
inside details as well. To show these, part of the outside “skin” is shown as if removed.
Imagine a banana being partly peeled, and you can see both outside skin and parts of the
inside of the banana. The edges of the removed “skin” are usually drawn irregular.
71
Example: Household Sand Filter
Cross-Section, Side-View, and Layout Plan of the same filter see 8.37/5
N) Conventions for Technical Drawing and Technical Signs
Conventions for technical drawing are fixed, agreed-upon signs used in technical drawings.
72
Small dimensions, thin
Cut wall, thick line, hatched
Boundaries, drawing not continued
Welding in cross-section
Connection of two pieces with bolt
End of pipe in side-view
73
Interruption
Long chain, thick: Cutting planes for sections
Edges, thin
Short dashes, thin:
Hidden details, edges not to be seen. The first and the last dash of a hidden detail line
should always touch the lines between which it is drawn.
Centre line of a rotational symmetric part:
Centre lines must project for a short distance beyond the outline of the feature to which
they refer.
Thin, long chain: Direction of part on exploded diagram
Line, indicating name or part No.
Radius and centre
74
Two parts threaded together
Concrete (in cross-section)
Brickwork (in cross-section)
Sand or clay (in cross-section)
Rock (in cross-section)
Timber (in cross-section)
Insulation (in cross-section)
Water table
Diameter
Equal angle steel
Square pipe
is roughly equal to
75
represents
is not equal to
is bigger than
is smaller than
Light
Key or switch
Socket and plug connected
Plug with two connections
Plug with three connections
Plug with five connections
O) Measurements and Scales
Always indicate on the bottom of your plan: “All measurements in m.” or “All measurements in
mm.” Write only the figures into the dimension lines, without the unit. Commonly, steel
construction and machinery is measured in mm; concrete, brick and timber work in m and cm.
In this case 60 means 60 cm, not 60 m; and 1.60 means 1.60 m and not 1.60 cm.
The measurements in this manual are mostly indicated like the latter, in cm and m.
Indicate also the scale on the bottom of your plan.
The most common scales are:
1:10 means: 1 cm on the plan = 10 cm in reality = 0.10 m in reality
1:20 means: 1 cm on the plan = 20 cm in reality = 0.20 m in reality
76
1:50 means: 1 cm on the plan = 50 cm in reality = 0.50 m in reality
1:100 means: 1 cm on the plan = 100 cm in reality = 1.00 m in reality
1:200 means: 1 cm on the plan = 200 cm in reality = 2.00 m in reality
You can calculate the scales as follows:
scale =
length on plan
length in reality
1. Example
How long do you draw 5 m in scale 1:20?
1
x
=
20 5 m
x=
5m
= 0.25 m = 25 cm
20
2. Example
2.5 cm on a plan in scale 1:50 represents which distance in reality?
1
2.5 cm
=
50
x
x = 2.5 cm x 50 = 125.0 cm = 1.25 m
6.2 Marking Rectangular Layout Plan
Many buildings are planned to be rectangular. It is very important that they are built in true
rectangular shape with 90° angles at each of the four corners. If the walls are out of the
rectangular shape, you will face difficulties when placing slabs, roof trusses, zinc sheets,
roofing sheets, floor tiles, etc., later on. If the walls are rectangular, these parts will fit without
any further adjustment. If not, lots of tiresome cutting or other manipulations will be
necessary. Therefore, it saves time in the long run to spend efforts on the correct layout. The
walls must be laid out correctly in the first place and the shape must be checked regularly.
There are two ways to mark a rectangular layout plan:
A) 3-4-5 Method
This method is based on the Pythagoras theorem (see 5.5/1)
a 2 + b2 + c 2
77
The numbers 3,4 and 5 fulfil the Pythagoras theorem:
3 2 + 42
9+16
= 52
= 25
This equation can be multiplied by any number on both halves of the equation and still fulfil
the theorem, e.g.
(32 + 42) × 4
3 2 × 4 + 42 × 4
(3 × 2)2 + (4 × 2)2
6 2 + 82
36 + 64
= 52 × 4
= 52 × 4
= (5 × 2)2
= 102
= 100
or
(3 × 0.50)2 + (4 × 0.50)2
1.52 + 2.02
2.25 + 4.0
= (5 × 0.50)2
= 2.52
= 6.25
Any triangle with the sides 3,4,5 or any multiples of 3,4,5 is a right angled triangle.
This connection is applied for marking a rectangular layout plan as follows:
1. Place “corner profiles” outside the four corners of the planned building.
Make the corner profile itself right angled with the help of a carpenter’s square.
2. Put the corner posts of the profile into concrete to prevent movement.
3. Mark the first side of the building by connecting a line between a nail on one corner profile
to a nail on the opposite corner profile.
78
4. Create a second line crossing the first one using the 3,4,5 method. Mark 3 units (e.g. 3 ×
0.50 m = 1.50 m) along one side with a string, mark 4 units (e.g. 4 × 0.50 m = 2.00 m) along
the other side. The angle is 90° if the distance between the two marks is 5 units (e.g. 5 × 0.50
m = 2.50 m). Fix the line with nails.
79
5. Connect all four sides like this taking care that the length of the sides is according to plan.
6. Check to see if the sides of the rectangle are according to plan and if the two diagonals are
equal.
7. Mark the nails which indicate the layout plan to avoid confusion.
8. Plumb the layout on the ground with a plumb bob.
9. Remove the lines during construction and connect them again whenever you need
measurements.
B) Method Using Diagonal
This method is useful for marking on level ground or on a cast (= poured) concrete floor. For
example, you may mark the layout on cleaned and level ground and erect corner profiles
afterwards (see A). The method is to be used as follows:
1. Calculate the diagonal of the rectangle with the given sides (see 5.5/1).
Example:
long side
short side
diagonal
1.90 m
1.60 m
2.485 m
2. Mark the long side of the rectangle (1.90 m) with nails (A) and (B).
3. Use a measuring tape stretched from corner (A) to create a diagonal that is 2.485 m long.
This diagonal now becomes the radius of a circle drawn around (A) with a nail on the ground.
4. Repeat the method in number 3., using a radius that is 1.60 m long (the short side of the
rectangle) around corner (B).
5. The intersection (= crossing point of the lines) of the two circles is the third corner (C). Mark
it with a nail.
6. Repeat the method in number 3., using a radius that is 1.90 m long (the long side of the
rectangle) to draw a circle around the third corner (C).
80
7. Draw a circle with the short side (1.60 m) around the first corner (A).
8. The intersection of the two circles is the fourth corner (D). Mark it with a nail.
9. Check if all the sides have the correct size.
10. Check if both diagonals are equal.
This method is very quick once the diagonal is known, and saves you difficult trial and error
and corrections.
C) Checking the Rectangular Shape during Construction
The rectangular shape of the walls must be checked regularly (at least every metre). Always
check the following two points:
1. Check if the length of the sides is correct.
2. Check if the two diagonals are equal.
The shape is rectangular only if both conditions are fulfilled. If not, make corrections; it may
be tolerated if the diagonals differ by 1 cm, but not if they differ by 4-5 cm.
6.3 Tools
Tools are essential for good craft work. The technician must have a basic knowledge about
tools in order to be able
81
- to select the suitable tools when purchasing,
- to use the correct tools for each purpose,
- to handle each tool in the right way to ensure optimal work and to avoid unnecessary
damage,
- to maintain each tool properly to ensure its long life.
The most basic information about these points is collected in the chapter for the following
kinds of tools (used in well construction and latrine building):
- general tools,
- special tools for concrete and brickwork,
- special tools for wood work,
- special tools for metal work.
Only the most basic tools of these groups are compiled here, because the purpose of the
chapter is to give a first introduction about tools for a technician trainee, completely new in the
field. She/he is introduced into the new vocabulary and has to learn the names, functions and
proper handling. Add the local names by yourself. When the technician is acquainted with the
tools compiled here, she/he needs to deepen her/his knowledge by further studies in tools’
catalogues and literature and by asking experienced people.
The full names and, if existing, several ones are listed. These names are not necessarily the
suitable ones for recording in the store. For example, a “square file”, as listed here, is better
recorded in the store as “file, for metal, square”; a “triangular file” is recorded as “file, for
metal, triangular”; etc. Thus, the stock cards of all different files will be close to each other
according to the alphabetical order (see also 7.9/1).
A) General Tools for Different Purposes
No.
1
2
Drawing
Name(s)
Description
Function
Remarks
measuring
with steel tape for
for reading the
tape 2m, 5m in
enclosed measuring meter
see
=
tape metal case with short
6.4/5f; prevent
measure 2m, spring return; distances in tape
from
5m
graduation
carpentry getting wet; if
wet,
dry
= meter 2m, metric and inch and
immediately
5m
concrete
oil
it;
=
pocket
work
or and
measuring
brickwork prevent folds
tape
steel,
glass for
Different alternatives for tape measuring
rewind
tape
10m, fibre or cotton measuring accurately;
zero positions
20m, 50m
tape in plastic long
never rewind
=
tape frame with grip distances; tape when it is
measure
or in capsule for marking wet;
for
10m,
20m, with fold-away layout
reading
the
50m
rewinding
plans;
for meter
see
= meter 10m, handle;
measuring 6.4/lff
20m, 50m
sometimes
well depth
plumb-loaded
82
No.
3
4
5
Drawing
Name(s)
Description
Function
Remarks
caliper
from polished for
for measuring,
=
vernier steel,
with measuring hold
the
inside/outsi caliper against
caliper
knife-edged
jaws
for de
the object as
internal/externa diameters shown in the
l measurements of pipes and drawing; use
and
depth internal/
the
vernier
external
gauge;
scale if you
graduated
in measureme want to read
and 1/10 mm
mm with vernier nts
of
scale to read depth
1/10 mm; with grooves
thumb roller or
friction lock
spirit level
from wood or for levelling steel
spirit
= carpenter’s steel, with two and
levels
are
level
vials, one level plumbing
more sensitive
and one plumb; short
on sun; never
the vials are distances; leave a spirit
from glass filled see 6.4/9f level in the
sun!,
once
with ether; a
spoilt by heat,
bubble can be
it cannot be
seen
repaired;
check
the
spirit level for
its
accuracy
on
every
possible
occasion
plumb bob
from iron with for
for using the
=
brass knob and plumbing, plumb bob see
engineering plumb line
especially in 6.4/11; never
bob
deep wells knot the plumb
line!
6
spring
balance
7
balance
8
blacksmithing one
hammer
rounded,
other flat
83
Tandy
scale, for
rough hang
the
with hook and measuring weight to be
spring
of kg
measured on
the hook and
read the scale;
might not be
exact
after
some time
with two bowls, for
exact
to be used with measuring
weights
of weights
end for
for
all
the blacksmithi hampers:
if
loose, fix the
ng
head
immediately
with
handle
wedges (see
No.12,6.3/6)
No.
9
10
11
12
13
14
15
Drawing
Name(s)
carpentry
hammer
Description
Function
Remarks
with
round, for
the neck is
crowned face carpentry suitable
to
and split neck work
extract nails
bricklayer’s
hammer
square
face, for
the other end bricklaying
sharp
for
cutting bricks
sledge
square
face for
heavy the
handle
hammer
and sharp end duty work must be fixed
or
double
well
square
face,
differentiated
according
to
weight
handle
three-pronged to fix the the
handle
wedges
wedges
from handle of a must tightly fit
=
hammer steel
hammer
the
hole;
bolsters
additionally,
hammer
the
wedge into the
handle
from
above
breast drill
with four jaws; for drilling for
square
= drill brace with eight-tooth holes
in shank
bits;
= carpenter’s ratchet and ball wood
lean against
brace
bearing head
the breast drill
to
improve
drilling
hand drill
with three-jaw for drilling for round shaft
chuck, handles, holes
in bits
two gears
metal,
wood, etc.
drilling
electrical
normal
for round shaft
machine
machine
with drilling for bits; start the
= rotary drill three-jaw
wood,
machine
=
portable chuck, with key metal, etc., before
drill
for opening the marked with touching the
chuck, electrical
; object;
drill
cable and plug percussion straight
drilling for
stone,
concrete,
marked with
;
percussion
means that
the bit drills
taps
and
against the
object
84
No.
16
17
18
19
20
21
22
23
Drawing
Name(s)
Description Function
Remarks
drilling bit for with
round for
drilling never
use
stone
shank
for brick, stone, lubricants!
= masonry hand drill or concrete,
the
drill
drill
electrical
glass, etc.
should
be
= concrete drilling
withdrawn
drill
machine; the
regularly to
tip has a hard
avoid
metal
or
overheating
carbide edge
drilling bit for with
round for
drilling avoid
blue
metal
shank
for metal
coloured
= twist drill hand drill or
metal chips
electrical
by reducing
drilling
drilling
machine
speed; blue
colour
indicates
overheating
drilling bit for with centre tip for
drilling first
press
wood
and
side small
the
tip
= lamp base cutters, with diameter
against the
drill
round shank holes
in wood, then
for hand drill wood
start to drill
or electrical
drilling
machine
centre bits with
round for
drilling see above
shank
for large
hand drill or diameter
electrical
holes
in
drilling
wood
machine
expansive
with square or for
drilling see above;
bits
round shank large
the bit is
for all types of diameter
adjustable to
drills
holes
in any diameter
wood
drilling bits with square for
drilling see above
for wood
shank
for wood
=
solid breast
drill,
centre auger screw tip and
bits
feed screw
pickaxe
From
steel, for loosening the
handle
with
one hard
soil must
not
broad sharp when digging move in the
and
one
pickaxe
pointed end
and wooden
handle
crowbar
thick iron bar for
digging keep
the
with
one pits or wells edge sharp
pointed and
one split or
sharp flat end
in
different
sizes
85
No.
24
25
26
27
28
29
30
31
Drawing
Name(s)
shovel
Description Function
Remarks
metal shovel for
lifting wash
the
with tip and sand, earth, shovel
long wooden gravel,
always
handle
concrete,
immediately
etc.
after work
spade
shovel-like
for
cutting put your foot
tool, but with and digging on the spade
straight edge into soft soil and press it
with
into the soil
additional
with the help
help of the of your bodyfoot
weight; then
take the cut
soil out using
the spade as
a lever
wheelbarrow with one tyre to
move keep
the
(full rubber or loads
wheelbarrow
with
inner
clean
and
tube), strong
well greased;
frame
and
can be made
two handles
locally from
timber
whitewash soft
nylon for
quick wash
brush
brittles
in painting
of immediately
=
chalk square wood large areas after use
broom
with handle with
whitewash
flat
paint light bristles for painting never allow
brush
with wooden with all kinds paint to dry
handle;
in of paints
on the brush,
different
but clean it
sizes, saneimmediately
times
with
after use
bucket rest
universal
pocket knife for
cutting break off the
knife
with
sliding nylon sheets, tip of the
= break-off blade
with carton, etc. blade when
blade knife plastic cover;
not
sharp;
the blade has
the new tip
perforations
will be sharp
funnel
from plastic or for pouring
metal,
fuel, etc. into
sometimes
small
with sieve
openings
safety
helmet
86
from plastic to reduce the always wear
with
rain risk
of a
safety
gully; textile injuries from helmet inside
fittings,
falling
the well see
leather sweat- objects
8.21
band,
tape
fastening
No.
32
Drawing
33
Name(s)
safety belt
Description Function
Remarks
with
broad for lifting and use in all
belts
from catching
a risky
nylon around person
situations;
chest
and
see
8.21,
shoulders
8.22
pulley
with single or for
pulling see 8.17/19;
=
pulley double
or ropes, steel never use a
block
triple roll from cables, etc. pulley which
steel, eye and
is broken in
hook;
any of its
sometimes
parts; grease
with
hinged
regularly;
snatch
for
avoid friction
easy removal
between
of a cable
rope
and
with a swivel
frame
hook on the
end
rope
from
sisal, for
pulling for
details
hemp
or loads
see 8.23
nylon,
with
different
diameters
34
B) Special Tools for Concrete and Brickwork
No.
35
36
37
Drawing
Name(s) Description Function
Remarks
trowels
from forged for brick and for using the
steel
with concrete
trowel
see
wooden
work;
for 6.7/10f; never
handle,
in spreading
allow mortar
different
mortar;
for to get hard on
shapes and rough cutting the trowel
sizes
of bricks
pointing
thin trowel
for pointing see above
trowel
and
other
fine work
plasterer’s triangle trowel for plastering see above
trowel
38
finishing
trowel
square trowel for smoothing see above
and finishing
plastering
39
float
wooden
smoothing
trowel
40
spatula
87
for
rough can
be
smoothing of manufactured
(concrete)
locally
surfaces
flat metal with for
filling
handle
in holes
with
different sizes gypsum and
and shapes smoothening
surfaces
No.
41
42
43
44
45
46
47
48
49
Drawing
Name(s) Description Function
Remarks
bricklayer’s nylon thread for building a
line
straight line
straight
from
dry for
making check
the
edge
timber
or level floors straight edge
steel
by
looking
along it; do
not leave it in
sun or rain
earth pan locally made for carrying never
allow
flat bowl from mortar
mortar to get
metal
hard on it,
because it will
increase
its
weight
bucket
from zinc or for carrying never
use
plastic
material
buckets with
worn handles
in wells
sieve
with
wire for
sieving sieve with two
mesh
in sand
and people
different sizes gravel; see
in
wooden 8.20/1
frame
wrecking from a steel to be used as make full use
bar
bar; one end lever arm; for of the lever
bent with a removing
arm
slot, the other nails,
end sharp
shutters from
concrete; for
rough work
wire brush brush
with for
dry keep
the
=
steel wire bristles cleaning
of brush dry
handand wooden tools
and
brush
handle
in equipment
different sizes
nylon
brush
with for
wet always clean
brush
nylon
cleaning
of tools
=
panel (synthetic
tools
and immediately
brush
fibre) bristles equipment
after work
in a wooden
frame
bolt cutter with clipper for
cutting place the bolt
cut jaws and reinforcement to be cut at
exchangeable rods
the end of the
blades
blade to make
full use of the
lever arm
88
C) Special Tools for Woodwork
No.
50
51
52
53
54
55
56
Drawing
Name(s)
cross-cut
saw
Description Function
Remarks
long saw with for cutting for all saws:
big teeth and logs
into never
use
two wooden sawn timber force,
but
handles to be
saw
with
used by two
speed
people
instead and
avoid
bending the
saw
by
bow saw
made of oval for cutting cut
steel tubing logs, poles, drawing and
in the shape rough work pushing
motion
but
of a bow; the
with
very
blade can be
little pressure
exchanged;
downwards
with
tensioning
arm to put
the
blade
under
tension
turning saw wooden
for cutting fix the blade;
=
joiner’s frame
with sawn
tighten
the
bow saw
blade,
timber; for wire and the
handles, wire exact work blade
by
for tightening
turning
the
the blade
adjusting nut
land saw
with straight for cutting see bow saw
teeth
or timber
universal
teeth;
with
wooden
or
plastic
handle;
in
different
sizes
tenon saw with square for cutting
=
dove-tail blade
and deep
saw
wooden
or grooves into
plastic
timber
handle
compass
very
thin for cutting
saw
blade
with small holes
=
keyhole handle
into timber
saw
plane
from steel or for
always clean
wood
with smoothing the surface
handle and wooden
of the timber
knob, smooth surfaces
to be planed;
sole, blade
the
blade
and screw for
must
be
adjusting
sharp
and
depth of the
straight;
cut
never
use
the
plane
with force
89
No.
57
58
59
60
Drawing
Name(s) Description Function
Remarks
rebate plane plane with a for cutting see above
special blade rebates
for a rebate
spokeshave with cap and for
see above
single cutter smoothing
and
rounding
curved
surfaces
wood chisel with
sharp for cutting use
a
edge,
a holes
into wooden
chamfered (= wood
mallet, never
bevelled)
an ordinary
blade
and
hammer;
wooden
sharpen the
handle
chisel often;
do not use it
as a lever
arm; hold it
as shown in
the drawing
wooden
special
for working see above
mallet
hammer from with wood
wood
chisels
61
rubber mallet special
for
hammer from hammering
solid rubber without
with wooden damaging
handle
the object
62
sharpening stone fixed in for
oil stone
wooden box; sharpening
= hone stone combination tools
stones
are
coarse
on
one side and
fine on the
other
90
sharpen with
long,
even
movements;
always use
with
oil;
sharpen your
tools
often
(after every
half hour)
No.
63
64
65
66
67
68
Drawing
Name(s) Description Function
table grinder hand
for
=
bench operated
sharpening
grinder
grinder with tools
grinding
wheel
Remarks
hold the tool
to
be
sharpened
against the
turning
grinding
wheel,
it
must
lay
parallel and
flat against
the
wheel;
never
use
force
screw auger auger
with to drill large fix a handle
screw tip and holes
into in T-form and
opening for a wood
drill
handle
without
a
machine
wood rasp with a series for rasping keep
the
of
pointed, wood,
for rasp dry and
individual
coarse work clean
teeth
in
soft
material
sand paper strong paper for manual put the sand
= flint paper coated with sanding of paper around
=
abrasive flint
wood
a piece of
wood
for
paper
proper grip
with bar of for fixing a push
the
steel, strong piece to the jaws together
jaws, a screw working
on the pieces
with plastic- bench or for to be fixed,
ball
jointed pressing
then screw
shoe
and wooden
the
handle
frames
wooden
tight
handle,
or together
steel
T- after gluing
handle; with
short or long
bar
sash clamp long clamp for pressing push
the
door frames jaws together
or
other on the piece
large
to be fixed,
objects
place the pin
together
into the next
hole,
then
screw
the
handle tight
clamp
91
No.
69
Drawing
Name(s) Description Function
work bench with built in for
vices;
with carpentry
wood
work
spindles
Remarks
locally made
work
benches can
be equipped
with a vice
70
trysquare
= square
metal square for marking the
stock
with
right right angles must be well
angle;
with or 45° on pressed
stock
and timber
against the
blade
timber when
marking
71
marking
gauge
with scribing for marking
bar,
carpentry
graduated in work
mm
72
axe
with
broad for splitting keep the axe
edge
and wood,
sharp
wooden
cutting
handle
trees,
preparing
poles, etc.
D) Special Tools for Metalwork
No.
73
74
Drawing
Name(s) Description
Function
Remarks
pliers
with single for all kinds of
=
joint,
pipe work
combination jaws,
pliers
serrated
gripping
surfaces
and
two
plastic
covered
handles
pincers
with single for
tying for
tying
joint and two reinforcement reinforcement
handles
with wire, for do not press
cutting wire, for the
pincers
extracting nails too much; for
extracting
nails use the
lever
arm
(see drawing)
92
No.
75
76
77
78
79
80
81
Drawing
Name(s) Description
Function
Remarks
self-grip
for
different adjust by endwith
wrenches serrated (= kinds of work adjusting
= vice-grip toothed),
screw
until
pliers
jaws slip over
adjustable
the work, then
jaws
with
snap handles
pipe
grip;
shut and jaws
can
be
will
engage
locked
on
with powerful
the job and
grip; release
stay locked
with release
with hands
lever
removed;
with quickrelease
lever (spring
loaded)
zinc
with snips for cutting zinc sharpen the
cutter=hand and
two or other metal snips
from
snips=hand handles
sheets
time to time
shears
punch
with sharp to mark a point
tip
on a piece of
metal or make
a start for a
twist
drill
(No.17, 6.3/8)
screwdriver with wooden for
screwing never use a
or
plastic screws with slot screwdriver
handle,
head
as lever arm;
sometimes
take care not
with
to
damage
hexagonal
the tip
shaft which
facilitates
the use of
spanners for
tightening
crosswith wooden for
screwing a
crossscrewdriver or
plastic screws
with screwdriver
=
Philips handle
Philips head
does not slip
screwdriver
away easily
open-ended double
for locking and only
use
spanner
ended, with tightening bolts fitting
=
open- jaw angles and nuts
spanners;
ended
15°,
in
carefully
fit
wrench
different
them on the
sizes, often
nuts; do not
in sets
damage the
jaws
ring
double
for loosing and only
use
spanner
ended with tightening bolts fitting
=
box 12-faced
and nuts; more spanners;
wrench
rings,
in force can be place
the
different
inserted
than spanner
sizes
with
open carefully on
ended
the nut
spanners
93
No.
82
83
84
85
86
87
Drawing
Name(s) Description
Function
Remarks
adjustable with
for loosing and adjust
the
spanner
movable
tightening bolts jaws so that
=
jaws,
and nuts of any they grip the
adjustable adjusted by size
nut exactly
wrench
a screw
= crescent
wrench
alien keys hexagonal for hexagonal use the long
=
alien rod in L- socket heads end as a lever
arm
wrench
shape;
in
different
sizes; often
in sets
socket sets with
bi- :or loosing and fit the socket
hexagonal tightening bots on the nut
sockets in and nuts
and
tighten
different
with
the
sizes
and
ratchet
ratchet
handle;
handle
quicker work
than with ring
spanners;
more
force
can
be
applied
cold chisel made from for cutting metal keep the tip
specially
pieces
or sharp; never
treated steel cutting
the
holes allow
into brickwork other end to
and concrete become
mushroom
shaped
hacksaw
steel frame for
sawing the
blade
frames
with handle metal parts
must always
and blade
be tight; do
holders
not
apply
force
when
sawing;
always mount
blade so that
teeth will cut
on the push
stroke,
see
drawing; see
also 8.32/12
hacksaw
steel blade for
sawing do not try to
blades
with teeth metal parts
saw
with
worn-out
Choice of suitable blade for
blades,
but
different materials:
replace them;
At least three teeth should be in
never replace
contact simultaneously.
a blade in the
middle of a
cut, because
this
would
spoil the new
blade;
see
also 8.32/12
94
No.
88
Drawing
Name(s) Description
Function
Remarks
angle
electrical
for cutting and hold
the
grinding
machine for grinding
machine
machine
cutting and
firmly; always
=
angle grinding
use
eyegrinder
discs
protectors
89
cutting disc consisting of for
= cutting-off cutting
grinder
wheel
medium and
bonding
agent
according to
the material
to be cut
90
grinding
consisting of for
disc
grinding
grinder
= grinding median and
wheel
bonding
agent
according to
the material
to
be
ground
shrubbing from
soft for
disc
material
grinder
91
92
93
angle use only for
cutting, never
for grinding;
tighten
the
disc
safely;
never
use
force; touch
the object to
be
cut
vertically and
without
pressure
angle use only for
grinding
never
for
cutting;
tighten
the
disc
safely;
grind without
pressure
angle use only for
smoothing the
surface
eye
plastic
for
protecting always
use
protectors glasses with the eyes
eye
=
safety front
and
protectors
goggles
side
when cutting
protection
and grinding
set
of consisting of for welding
welding
welder’s
equipment screen,
2
cables with
connections,
1 electrode
holder,
1
earth clamp,
1
wire
brush,
1
chipping
hammer
95
the
cable
area Ø must
fit the welding
generator’s
specification
No.
94
Name(s) Description
Function
soldering with square for soldering
iron
copper
section and
wooden
hand grip
Remarks
warm up in
open fire and
solder
95
anvil
the anvil must
be mounted
on a wooden
block
to
absorb
vibration
96
flat file
97
98
99
100
101
Drawing
with plane for
work
blacksmithing
surface
of
for sharpening for all files:
rectangular flat
metal keep
them
shape, one surfaces
and dry and clean
edge uncut, sharp corners
with double and blunts
cut
threedouble cut for
finishing
square file sides, uncut inside corners,
= triangular top
slots, etc.
file
square file double cut for
filing
on all four grooves,
sides
rectangular
holes
and
inside
shoulders
round file double cut for round and
concave
surfaces
half round double cut, for
finishing
file
all around concave
and
plane surfaces
and
larger
holes
file brush fine and flat for
cleaning keep
the
= file card wire inrush files
brush dry
Cut:
Length:
The length of the file Files are divided into four cuts:
does not include the tang single, double, milled tooth,
(= the projecting part by and rasp.
which the blade is held in
the handle). The length Single cut files are for filing
of the file should be steel and metals with normal
chosen according to the working pressure.
size of the workpiece:
the larger the workpiece, Double cut files consist of two
the larger the file. It is diagonal cuts. They are used
better to choose a file at higher working pressure
that is too long than one than single cut files for iron,
that is too short to steel, but also plastics, wood,
ensure stability when etc.
working.
96
No.
102
Drawing
Name(s) Description
Function
Remarks
Degree of Coarseness: Milled tooth cut files are used
for smoothing the surface in
Files are divided into the car-body repair work. The
following degrees of teeth form curves over the
coarseness:
rough, surface of the file.
bastard,
median-fine,
Rasp cut files have a series of
fine.
pointed, individual teeth. They
Fine files are used for are used for coarse work in
hard material where a soft material, e.g., wood,
good finish is required, plastic, aluminum, leather, etc.
while coarse files are
used on soft material
where a rough surface
can be tolerated.
vice
with
steel for
holding keep the vice
jaws
and items firmly
well greased;
spindle;
do not use
sometimes,
force
pipe
jaws
under
the
smooth jaws
103
pipe vice
104
chain
vice
105
fixing for handling
pipe wrench with
two for
threaded pipe pipe
Swedish
serrated
joints
type
wrenches see
jaws,
8.32/14f;
adjusted
optimal grip
with
a
only in one
positioning
direction
screw; the
jaw
angle
can be 90°
or 75°; with
two handles;
in different
sizes
with
pipe for
holding keep the vice
support and pipes firmly
well greased
ringed jaws
pipe the pipe is for
holding fix the chain
held
all pipes firmly
as firmly as
around with
possible, then
a chain
screw
the
handle
97
No.
106
107
108
109
110
111
Drawing
Name(s) Description
Function
Remarks
pipe wrench with
two for
fixing grip only in
British type serrated
threaded pipe one direction
jaws,
joints
adjusted
with
a
positioning
screw; with
a
spring;
only
one
handle
chain
with chain, for fixing and fix the chain
wrench
double
holding pipes or as firmly as
toothed,
irregularly
possible, then
reversible shaped objects move
the
jaws
and
handle; grip in
one handle
both
directions
possible
pipe cutter with cutting for cutting pipes never
use
wheel, two
force; fit the
guiding
cutter on the
wheels and
pipe, screw
adjustable
the
handle
handle
until
the
cutting wheel
touches the
pipe cut one
round, screw
the
handle,
cut
one
round,
etc.;
always
use
cutting
oil;
see 8.32/12
thread tap with straight for tapping (= always
use
flutes
to cutting) internal with
thread
deliver the threads
for cutting
oil;
swarf
(= bolts and pipes; never apply
chips) out of the tap must fit force
the
hole; to
the
with square specifications of
shank
the thread (for
threads,
see
8.32)
series taps for
pre- for
tapping the three taps
cutting,
internal threads have to be
medium
with very good used
one
cutting and finish
after the other
fine cutting
tap wrench adjustable for holding taps
for different
taps,
with
two handles
98
No.
112
113
114
115
116
Drawing
Name(s) Description
Function
Remarks
threading round dies for
threading check
for
starting point
dies
=
external
threading
threads of bolts, by noting the
dice
pump
rods, tapered side
etc.; the dies (not the sharp
must fit to the side); use the
dies always
thread
thread
specifications with
oil;
(for threads see cutting
never apply
8.32]
force
die stock
for different for holding dies fix the die in
dies
with
the stock as
two handles
shown in the
drawing
tap and die contain tap for
cutting the taps and
sets
and dies of internal/external dies are well
different
threads of bolts; protected and
sizes,
the taps and complete in a
complete
dies must fit to set, however,
with
tap the
thread some
wrench and specifications diameters
die stock in (for threads see wear
out
a box
8.32)
quicker than
others
pipe thread with ratchet; for
cutting always insert
die
stock automatic external
pipe the chasers in
(with chaser centering; threads;
one the indicated
dies)
right and left die stock can order;
=
pipe hand
be used for suitable also
threader
threading
different
if the pipe ∅
=
thread possible;
threads
is
different
cutter
for chaser dies
from
the
pipes
can
be
specifications;
exchanged
open
the
Ear taper or
chaser dies
cylindrical
after
threads; one
threading,
set
of
screwing
chaser dies
back on the
suitable for
thread
is
different
necessary;
pipe
the
ratchet
diameters,
allows to turn
because the
the
handle
diameter
conveniently
can
be
back
and
adjusted
forth instead
of screwing
continuously
chaser dies 4
chaser for fitting into replace
the
dies in one pipe thread die chaser dies if
set, suitable stock
worn out or
for different
chipped
(=
pipe
part broken
diameters,
off)
because the
diameter can
be adjusted
99
No.
117
118
Drawing
Name(s) Description
Function
Remarks
pipe thread separate
for
cutting quick change
die
stock screw heads external
pipe between
(with
for
each threads;
the various
separate
diameter;
screw
heads thread sizes;
screw
with right or must fit to the the
pipe
heads)
left
hand thread
diameter
ratchet
specifications must
fit
(see 8.32)
exactly to the
specification
thread
folding
for measuring hold
the
gauge
= blades with internal
and gauge against
screw pitch gauges for external
the thread; if
it fits read the
gauge
different
threads
specification
threads
119
cutting oil there
are for lubricating continuous
cooling lubrication is
=
thread two types: and
cutting oil 1.
on while threading necessary;
this
will
biological
ensure better
base
for
threads and
threading
increased life
drinking
of
the
water pipes
threading
2.
on
tools
mineral
base for all
other
threads
120
oil can
121
lifting hook from forged for
=
swivel steel
with weights
hook
safety catch
100
with
for oiling tools, keep
the
reservoir,
etc.
spout clean
spout and
pressure
pump
lifting the
safety
catch must be
intact and the
load
must
hang inside
the
safety
catch;
see
also 8.17/20
No.
122
Drawing
Name(s) Description
Function
Remarks
thimble
dropfor permanent tighten
the
shaped,
eyes of steel wire rope grip
from
cables
closely to the
galvanized
thimble; see
steel
also 8.17/16
No.
123
Drawing
Name(s) Description
Function
Remarks
shackles
U-shaped for connecting see
also
= D-shackle with
bolt, the eye of a 8.17/19
different
steel cable with
sizes
for other elements
different
weights
124
125
126
connecting eye
from for
quick see
also
links
steel
rod connection of 8.17/19
which can steel
cables,
be opened; ropes
alternatively
with
screwed
connection
wire
rope the cables for fixing two for
lifting
grip
to
be wire ropes (= devices use 3
= wire rope connected steel
cables) wire
rope
clamp
are inside a together
grips for each
=
cable U-bolt and a
connection;
clamp
cross piece
see 8.17/16
is pressed
against
them
by
nuts
hose clips
101
from steel for
tightening use 2 hose
band
with hoses on a clips for each
rolled-up
fitting
connection
band edges
to prevent
the
band
from
cracking,
tightened
with bolt
6.4 Using Measuring Tools
Correct measuring is essential for good quality technical work. Many mistakes happen due to
incorrect use of measuring tools. The technician needs to learn and practise the correct use
of measuring tools.
The most basic measuring tools such as measuring tape, spirit level and plumb bob are
explained here.
A) Measuring Tape
The tool for measuring distances is called “measuring tape”, “tape-measure”, or “meter”.
Note:
meter = measuring tool
metre = unit of length in metric system
Measuring tapes are supplied in different length: 2m, 5m, 10m, 30m, 50m, etc.
Note that all illustrations in this chapter are not to scale!
1. Reading Measuring Tapes 10m, 30m, 50m (see also 6.3/2f)
Long measuring tapes are normally from flexible material like plastic. The tape is wound up
into a round box. Often metric measurements are on one side of the tape, and British
measurements are on the back.
The tape is marked with short lines and long lines crossing the whole width of the tape. Only
the long lines are marked with numbers. If the number consists only of one figure, the figure
stands left from the line. If it consists of two figures (or a figure and a letter), they are left and
right from the line:
a) Measuring Tape in Metric System
The tape in the metric system measures m, dm, cm.
The short lines indicate cm. Every fifth cm is indicated with a longer line with arrow for better
orientation. No numbers are given for cm. You have to count them yourself. Every tenth line is
a long line and is indicated with the appropriate length.
For example:
102
These numbers in black (the two figures left and right of the long line) indicate cm.
For measuring a length between two numbers:
- Read the previous cm indication.
- Count the cm.
- Add the two.
Previous cm indication:
cm counted:
length measured:
50 cm
6 cm
56 cm
Full metres are indicated as 1 M; 2 M; ... 9 M; 10,11,..., and are printed in red for
differentiation. Any black number for cm beyond 1 m is marked with a small red number
indicating the metres.
Read measurements bigger than 1 m as follows:
- Read the previous small read number as m.
- Read the previous number in black.
- Count the cm.
- Change all into one unit (e.g. m). For transformation see 5.3/1.
- Add the three.
Previous m indication:
previous cm indication:
cm counted:
length measured:
20 m =
10 cm =
8 cm =
20.00 m
0.10 m
0.08 m
20.18 m
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Take special care immediately after a m indication:
previous m indication:
previous cm indication:
cm counted:
length measured:
10 m =
-3 cm =
10.00 m
0.03 m
10.03 m !!
For comparison:
b) Measuring Tape in British System
The tape in British system can measure inch (= “) and feet (= ‘). The short lines indicate half
inches. The long lines indicate inches; the numbers are given in black. If the number consists
of two figures, one is left, the other right of the relevant line. Inches are numbered from 1 to
11. The twelfth inch completes a foot which is indicated in red as 1 F, 2 F,... 9 F, 10,11, etc.
Read measurements as follows:
- Read the previous red figure as foot.
- Read the previous black figure as inch.
- Read
1
-inch.
2
- Add up the three.
previous foot indication:
previous inch indication:
half inch:
length measured:
12’
3”
1
“
2
1
12' 3 “
2
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2. Reading Measuring Tapes 2m, 5m (see also 6.3/2f)
Short measuring tapes are usually made from a stiff metal strip, wound up by a spring into a
small, handy round or square box. Often the tape shows British measurements on the top half
and metric measurements in the bottom:
Read either of them, but keep them strictly apart, especially the numbers, and be careful not
to get mixed up.
a) Metric Side
On the metric side you can measure cm and mm. The short lines indicate mm without
numbers. You have to count them yourself. Every fifth mm (=
1
cm) is indicated with a middle
2
size line for easier counting. Every tenth line is a long line marked with a number which
indicates cm from 1 cm to 9 cm. Every tenth cm is indicated with a fat number: 10, 20,...90.
After each of these, the cm are marked again from 1 to 9. 1 m is indicated as 100 cm.
Read the measuring tape as follows:
- Read the previous fat number (with 2 or more places) as cm.
- Read the previous single number as cm.
- Count the mm.
- Change the mm into cm. For transformation see 5.3/1.
- Add all three.
- Change to m, if necessary.
previous fat number:
previous single number:
mm counted:
length measured:
130 cm =
2 cm =
6 mm =
130.0 cm
2.0 cm
0.6 cm
132.6 cm = 1.326 m
Take special care immediately after a m indication:
105
previous fat number
previous single number:
mm counted:
length measured:
100 cm =
3 cm =
2 mm =
100.0 cm
3.0 cm
0.2 cm
103.2 cm = 1.032 m
For comparison:
b) British Side
1
1 1
1
“,
“,
“,
“. The short lines indicate
2
4 8 16
1
1
“; every second short line is a bit longer and indicates
“; every fourth line is middle size
8
16
1
1
and indicates either
“ or
“, all of them without numbers. Every long line indicates an inch
4
2
On the British side you can measure inches,
with its number.
106
B) Spirit Level (see also 6.3/4f)
A spirit level (= plumb level) can measure whether a floor is level (= horizontal) or a wall is
plumb (= vertical).
For levelling, use it like this:
- Lay the spirit level on the object to be levelled.
- Wait until the bubble has settled in the tube.
- The object is level if the bubble is in the middle between the 2 marks on the tube:
- Turn the spirit level like this:
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If the indication is the same, the spirit level is functioning well.
For plumbing use it like this:
- Press the spirit level flat against the wall. There must be no gap between the spirit level
and the wall.
- Wait until the bubble has settled in the tube.
- The wall is plumb if the bubble is in the middle between the two marks on the tube.
- Turn the spirit level with its other edge against the wall. If the indication is the same, the
spirit level is functioning well. (see drawing above).
C) Plumb Bob (see also 6.3/4f)
A plumb bob (= engineering bob) measures whether a wall, a well, etc., is plumb (= vertical)
or not. For a deep well a plumb bob is more practical than a spirit level.
Use it as follows:
- Hold the wooden peg of the plumb bob against the wall.
- Slowly allow the plumb to move downwards by releasing the line. Avoid swinging
movement.
- If there is a gap between plumb and wall, the wall is not plumb.
- If the plumb is resting against the wall, the wall is not plumb.
- If the plumb freely hanging just touches the wall, the wall is plumb.
- If the line is torn, replace it with a new line - never knot it.
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6.5 Building and Other Materials
Mt 7,24-27
The main features and properties of building and other materials are listed below in brief form.
A) Materials for Walls, etc.
1. Concrete
see chapter 6.6
2. Brick
- made from fired clay,
- lots of firewood needed and, therefore, deforestation encouraged,
- good strength,
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- good resistance against weathering,
- fire resistant,
- good heat insulation,
- good sound insulation,
- allows moisture movement in the wall,
- recycling possible.
3. Mudblocks (see also 6.8)
- produced as sun-dried clay brick
- better quality if about 30% sand and 5 to 30% clay/silt,
- durable if wall protected from rain, ants and soil movement (by foundation and ant
course),
- recycling possible.
4. Stabilized Mudblocks (= Mud Bricks)
- produced in block-making machine (Cinva Ram, Bre-Pack) and then air-dried,
- consisting of clay with 7 to 10% cement or lime added,
- partial hydration takes place,
- curing necessary,
- high durability,
- good resistance against rain,
- recycling possible.
B) Mortars and Plasters
1. Cement
see chapter 6.6
2. Lime
- 2 types of lime:
* hydraulic = capable of setting under water,
* non-hydraulic = not capable of setting under water,
- produced from heated (to 1,000°C) and ground limestone,
- water to be added before use (= “slaking”),
- slow hydration (over decades),
- durable,
- used for brick and stone walls,
- also used as whitewash for painting,
- expensive in Sudan,
- recycling possible.
3. Mud Mortar
- used for fired bricks and mudblocks,
- durable if protected against rain,
- inexpensive,
- recycling possible.
C) Locally Available Materials
1. Sand
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- fine sand suitable for water filters and plastering,
- coarse sand suitable for concrete,
- sand without silt and impurities needed for concrete.
2. Gravel
- gravel without silt and impurities needed for concrete,
- broken rock with rough surface stronger than smooth pebbles.
D) Timber
1. General Properties
- strong; has compressive and tensile strength,
- light,
- durable if protected from moisture and ants,
- weak when wet, and strong when dry,
- strength 30 to 40 times greater along the grain than across it,
- great loss in strength at knots,
- recycling possible.
2. Production
- planting trees,
- cutting logs in dry season,
- drying logs (= seasoning),
- cutting logs into sawn timber,
- drying timber (correct way of storage see 7.10/3),
- ready for use, replanting trees.
3. Decay
- by weathering (sun, rain),
- by fungus attack (in wet and warm atmosphere),
- by insect attack, especially termites.
4. Protection
- by using well seasoned timber,
- by building in such a way that timber parts can dry easily and are not continuously
wet,
- by ensuring ventilation,
- by ant courses,
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- by painting,
- by avoiding painting before woodwork is dry,
- by painting with chemicals,
- by painting with old engine oil,
- by soaking in tar.
5. Softwood
- very soft,
- easily workable,
- grows quickly,
- no resistance against termites.
6. Hardwood
- the slower the growth, the harder the wood,
- difficult to work,
- very durable,
- termite resistant.
E) Roofing Materials
1. Zinc
- galvanized iron (= iron coated with zinc),
- very much energy needed for production,
- rust prone,
- fireproof,
- light,
- durable,
- easy to install,
- very hot, no insulation,
- expensive,
- not locally produced,
- no recycling possible,
- rainwater catchment possible.
2. Tiles
- produced from fired clay,
- lots of firewood needed for production, therefore, deforestation encouraged,
- heavy,
- fireproof,
- no corrosion,
- can break,
- durable,
- cool,
- locally manufactured,
- relatively expensive,
- good appearance,
- recycling possible,
- rainwater catchment possible.
3. Grass (see also 6.8)
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- produced by nature,
- light,
- not fireproof,
- durable only if thatched in a special way and with sufficient grass,
- prevention from ants by ant course or by separation of wall and roof structure
necessary,
- locally available,
- cool,
- skilled thatchers locally available,
- reasonable costs,
- recycling possible,
- not optimal for rainwater catchment.
4. Asbestos Cement Sheets
- made of cement mortar and asbestos fibres in the shape of zinc sheets,
- mining of asbestos and production causes sickness and death of many workers,
- not corrosive,
- light,
- fireproof,
- relatively durable, however, rain washes asbestos fibres into the groundwater (can
cause cancer),
- hot,
- easy to install,
- expensive,
- not locally produced,
- no recycling possible,
- no rainwater catchment possible because of asbestos fibres.
5. Fibre Reinforced Cement Sheets (see also 6.6/3 and 6.6/13)
- made of cement mortar and fibres (like sugar cane, coconut, or sisal fibres) in the
shape of zinc sheets,
- no danger to humans,
- not corrosive,
- light,
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- fireproof,
- relatively durable,
- hot,
- easy to install,
- expensive,
- eventually locally produced,
- no recycling possible,
- rainwater catchment possible.
6. Aluminium Sheets
- aluminum sheet with sharp edged profile:
- very much energy needed for production,
- corrosion prone,
- light,
- not fireproof,
- moderately hot (because of high reflection of sun rays),
- not durable,
- easy to install,
- very expensive,
- not locally produced,
- recycling eventually possible,
- rainwater catchment possible.
F) Ferrous Metals
1. General Properties
- all made from the raw material iron ore,
- density (= weight per unit volume in kg/dm3, see 5.7/1): all ferrous metals have a high
density, i.e., they are heavy,
- elasticity (= the capability of metal to recover its size and shape after deformation by
forces),
- plasticity (= the lack of capability of a metal to recover its size and shape after
deformation by forces; the capacity for being molded or altered; the ability to retain a
shape attained by pressure deformation),
- ductility (= the capability of metal of being drawn into fine wire),
- malleability (= the capability of metal of being shaped by hammering or rolled into
sheets without fractures),
- hardness (= the ability of metal to withstand scratching and wearing),
- corrosion resistance (= the ability of metal to resist corrosion from water, air or acid),
- electric conductivity (= the ability to transmit electricity),
- thermal conductivity (= the ability to transmit heat or cold).
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2. Wrought Iron
- less than 0.1% carbon,
- wrought (= formed by application of mechanical force) in either hot or cold state,
- almost pure iron,
- easily formed by blacksmithing,
- used for chains, crane hooks, doors, gates.
3. Steel
- 0.1 to 1.5% carbon,
- made from iron by melting,
- easily formed by blacksmithing,
- weldable,
- cannot be hardened,
- high elasticity,
- limited durability (corrosive),
- used for reinforcement, steel bars like equal angle steel, etc., drums for fuel, parts of
cars, pipes.
4. Stainless Steel
- high durability (not corrosive),
- weldable,
- very expensive,
- used for pots, knives, watches, measuring instruments, special machinery parts.
5. Cast Iron
- 2 to 4.5% carbon,
- cast (= pouring the molten metal into a mould),
- blacksmithing not possible,
- not weldable,
- can be hardened,
- brittle (= can crack and break),
- sparking red when ground,
- deep sound,
- used for cast parts like motor block, main part of diaphragm pump, etc.
G) Other Metals
1. Aluminium
- bluish silver-white metal,
- high strength compared to weight (low density),
- low hardness: soft on the surface,
- easy to work,
- no blacksmithing possible,
- welding only with inert gas welding,
- corrosion prone,
- surface gets grey through oxidation which protects against corrosion,
- easily attacked by salty water,
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- high reflectivity,
- high ductility and malleability,
- used for tins, aluminium foil, airplanes, etc.
- cast aluminium used for base plate of pipe moulds.
2. Copper
- reddish colour,
- low hardness: soft,
- high durability: no corrosion,
- high ductility and malleability,
- easily workable; also cold workable without cracking,
- can be soldered,
- green surface through oxidation,
- high conductivity for heat and electricity,
- used for electric cables, cooking pots, etc.
3. Brass
- yellow copper and zinc alloy (= molten mixture),
- workable in cold state,
- soldering possible,
- used for coating metal sheets, bearing surface, jewelry and decorations, etc.
H) Paints
1. General Properties
- preserve (= keep from decay),
- protect surfaces,
- decorate surfaces,
- enable the surface to be cleaned easily.
2. Components
- pigment (= base), a powdered substance, gives colour and provides opacity (= the
quality of being impervious to the rays of light),
- liquid (= vehicle), carries the pigment and consists of binder, thinner and drier,
- binder, fixes the pigment to the surface to be painted,
- thinner (= solvent), reduces the viscosity of the paint and helps the paint to penetrate
into the surface,
- drier, increases the speed of drying.
3. Oil Paints
- paint with oil as vehicle,
- for priming coats,
- for under-coats,
- for finishing coats,
- dries by evaporation of the solvent and oxidation.
4. Synthetic Paints
- paint produced by chemical synthesis,
- has a better flow than oil paint, therefore, easy to apply,
116
- sets quicker than oil paint, dries by evaporation of the solvent, oxidation and chemical
change.
5. Metal Paints
- paint with powdered metal as pigment,
- used for primer coats to prevent corrosion.
6. Whitewash
- paint from lime and water,
- not water proof,
- used mainly for whitewashing inside walls.
7. Water Paints
- paint using water as vehicle with chemical additions,
- cement paint with white or coloured portland cement as pigment, watertight, for
outside paints.
8. Varnishes
- liquid preparation forming a transparent coating when dry,
- oil varnishes,
- spirit varnishes.
6.6 Cement and Concrete
Cement and concrete are very important materials in construction, especially in water supply
and sanitation. Only the most basic knowledge, important for the day-to-day work, is compiled
here.
A) Cement
Cement is an adhesive substance in powdered form with the ability to bond aggregates
together to form concrete.
1. Manufacture of Cement
Cement is manufactured according to the procedure shown on the next page.
The main constituents of cement are:
1. Calcium Oxide (CaO) in the limestone
2. Silicon Oxide (SiO2) in the clay
During manufacturing and heating, carbon dioxide is removed. The final product, cement,
consists of 3 CaOSiO2. The substance produced has completely different properties from the
parent substances.
If salty water is used for making concrete, the salt reacts with the cement and, therefore, less
cement is left for hydration. Salt can also appear on the surface. Salt will also enhance
corrosion of the reinforcement.
Therefore:
117
Avoid using salty water for concrete, if possible. Otherwise, add more cement.
Procedure for Manufacturing Cement:
1
winning the raw-material
2
3
4
mixing
firing
grinding and treatment
2. Hydration of Cement
The setting of cement is a chemical process called “HYDRATION”. It is a chemical reaction,
not just a drying process. Complete hydration takes about one year. Heat is released in the
beginning of the process.
setting
cement + water + aggregates ⎯⎯ ⎯
⎯→ concrete + heat
The hydration of concrete is an irreversible process. Comparison between mud and fresh
concrete shows that no hydration takes place in mud mortar; the process is reversible.
clay + water
mud brick
If cement once touches water, hydration starts to take place.
Therefore:
Take care that the cement never gets wet before use! Crushing hardened cement into powder
never produces cement again.
B) Different Types of Concrete and Mortar
Concrete is an artificial stone made by mixing aggregates, water, and cement as adhesive
substance. These components form a new body.
Mortar is a pasty substance made by mixing fine aggregates (like sand) with an adhesive
substance (cement or lime or silt).
We differentiate the following types:
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Type
(plain) concrete
reinforced concrete
mudblocks
stabilized mudblocks
cement mortar
mud mortar
ferrocement
adhesive
substance
= cement +
= cement +
= silt +
= cement +
= cement +
= silt +
= cement +
aggregates
water
sand + gravel +
sand + gravel +
sand + clay +
sand + clay +
sand +
sand + clay +
sand +
water
water +
water
water
water
water
water +
fibre reinforced concrete
= cement +
sand +
water +
reinforcement
steel
chicken wire +
welded mesh
fibres
The different mixtures look like this:
1. Concrete (cement, sand, gravel), for example 1:3:4
The stones have great strength themselves and contribute to the final strength of the
concrete. The voids between the big stones are filled by smaller ones. All the stones are
connected with each other (“glued together”) with mortar (cement + sand + water) and, thus,
form the final concrete.
2. Concrete with only Big Gravel
There is no middle-sized gravel to fill the voids. Such concrete is weaker. Therefore, all sizes
of aggregate are needed for good concrete, such as big stones, small stones and sand. They
are all embedded in “cement milk”. The hardening cement milk connects all the aggregates.
Therefore:
The correct proportion of the aggregates is very important.
3. Concrete with too Much Water
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Only a certain amount of water is needed for the hydration process. The rest forms bubbles.
Gradually the water in the bubbles evaporates and leaves air bubbles behind which weaken
the concrete.
Concrete which is not well compacted also has air bubbles which weaken the concrete.
Therefore:
Too much water and air in the concrete reduce the strength. Mix with just the necessary
amount of water and compact properly.
4. Porous Concrete, for example 1:0:4
Porous concrete is concrete without sand for filter rings, permeable for water.
The gravel is surrounded by a thin layer of cement slurry which also connects the different
stones. The voids remain empty and, later, allow the water to pass through the concrete.
Obviously, porous concrete has less strength than ordinary concrete.
5. Mortar, for example 1:8
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The aggregate which in the case of mortar is only sand is connected by the cement slurry.
C) Strength of Concrete
The strength of concrete grows gradually, as shown in this graph:
After one day, concrete is still very weak and can be easily broken. After seven days, it
already has about half of its final strength, but not enough, for example, for a beam or slab to
be loaded or for a hand pump platform to be used. After 28 days the concrete has almost all
its final strength, and there is no need to wait for a further increase in strength. The concrete
can be fully used.
Too early loading of concrete may cause inward cracks which are not visible outside but
which greatly reduce the strength of the concrete and invite further destruction.
The concrete has no strength in the first days. If it is allowed to dry too quickly or is even
exposed to sun, it will shrink and develop cracks. These cracks will never close again. If the
concrete is kept wet, cracking is avoided until the strength has developed. Afterwards the
concrete will develop no cracks (or fewer cracks). Cracks lead to further destruction: Water
will enter and cause corrosion of the reinforcement, and the concrete will start to break and
crumble further with time.
Therefore:
- Do not step on fresh concrete on the first day.
- Shutters can be removed after 6 to 12 hours from the side.
- Slabs or beams need to be supported from underneath for 3 weeks!
- Turn over concrete rings after 48 hours, at the earliest.
- Do not lift slabs before 7 days.
- Do not load slabs or beams before 3 weeks.
- Do not lower a concrete ring before 3 weeks.
- Do not pump on a handpump platform before 3 weeks.
- Keep the fresh concrete wet for 3 to 7 days.
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D) Making Good Concrete
Two different pieces of concrete work might look the same immediately after completion, but
the difference shows later. Making good concrete requires a lot of effort and hard work. The
result will be a very durable concrete. Concrete can also be made carelessly. This concrete
will later crack and spoil. Although the workers have seemingly saved work and time in the
beginning, eventually it will turn out that both work and material were wasted.
For making good concrete, keep the following rules:
1. Use clean, sieved sand (silt content less than 0.5%).
2. Use clean, washed gravel.
3. Remove all organic material like grass, leaves, and mud. Organic material disturbs the
chemical process of hydration.
4. Use the materials in the correct proportion (= mixture).
5. Use enough water for good workability, and no more. Too much water reduces the
strength.
6. Use clean water and, if possible, not salty water.
7. Mix the concrete very well to ensure that every grain of the aggregate is coated with the
binding material so that maximum strength is assured. First, mix sand and cement while
still dry. Turn the heap over at least three times until it has an even, grey colour. Add
water. Do not pour the water from high, but slowly and gently. Turn over again three times.
Add gravel. Turn over again.
8. Pour the concrete gently, not from high, and compact it well. All air bubbles, which
weaken the concrete, must be removed.
9. Keep the concrete wet for three to seven days depending on the climate. This is called
“curing”. Cover the concrete with wet sand about three hours after pouring and with nylon
sheets, or with wet sacks. Pour water over it daily.
E) Properties of Concrete
Good concrete has the following properties:
- It is easy to cast into any form.
- It is very strong.
It has a high compressive strength (= strength to resist compression or being pressed
together).
It has a very low tensile strength (= strength to resist tension or being pulled or
stretched).
- It is very durable.
- It is a bad insulator, because it has no air bubbles. Concrete houses are very hot.
- Concrete walls do not “breathe”, that is they do not allow any exchange of air and,
therefore, concrete creates an uncomfortable atmosphere for human beings.
- It has bad sound insulation.
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- It is very difficult to break down concrete and discard it when it is no longer needed. It
cannot be recycled.
- It needs little maintenance.
- Concrete is not fireproof. Concrete cracks in fire and reinforcement melts.
These properties qualify concrete as the optimal building material for some purposes (e.g.
well rings, latrine slabs, etc.) and not the optimal material for others (e.g. walls for
accomodation, etc.).
F) Reinforced Concrete
1. Concrete Reinforced with Steel
Non-reinforced concrete is used where only compressive strength is required; that is, in all
parts which are continuously supported, like foundations, floors, etc., where the concrete is
only pressed.
Reinforced concrete is used where both compressive and tensile strength are required,
because the parts are not continuously supported, i.e., in beams, slabs, ventpipes.
The “tasks” are distributed as follows:
- Concrete, cheap and light, takes the pressure.
- Reinforcement, heavy and expensive, takes the tension.
The concrete protects the reinforcement from corrosion, because it prevents air and water
from reaching the reinforcement. This protection can only work if the rods are well embedded
in the concrete and if there are no (or few) cracks.
Therefore:
Reinforcement must never be seen on the outside surface of the concrete. There must always
be 1-2 cm concrete between the surface and the reinforcement.
2. Position of Reinforcement
Correct positioning of the reinforcement is essential. If the reinforcement is put into the wrong
position then the beam, slab, etc., will have no strength to carry their load. The correct
position of the reinforcement is determined by the planning engineers.
Therefore:
Place the reinforcement exactly into the location where indicated on the plan.
The position of the main reinforcement of some parts is explained here for better
understanding.
First, imagine how the part would bend under load and where it would start to crack. The
reinforcement is placed on the side where the part would be stretched. The reinforcement
shall prevent the cracks by holding the part together.
Example 1: Supported Beam (or Slab)
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Note: The deformation (= bending) of the part is exaggerated in this and all following
drawings!
Example 2: Cantilever
Example 3: Concrete Ring (when rolled on the ground or used as culvert)
124
Example 4: Concrete Ring (in the well)
Example 5: Foundation Slabs for Buildings on Black Cotton Soil
Black cotton soil contracts and expands seriously according to the water content and
develops big cracks in dry season. It can cause foundations and buildings to crack. Therefore,
foundations for buildings on black cotton soil need to be reinforced.
The soil can make the foundation bend in two ways:
Therefore, reinforcement is needed in the top and the bottom of the foundation: not in the
middle.
125
Example 6: Columns (can be bent into any direction; therefore, they need reinforcement in all
corners)
Example 7: Water Catchment Tanks
Water catchment tanks are continuously supported. Therefore, they do not need
reinforcement to carry loads (to prevent bending). However, they are reinforced with welded
mesh or chicken wire to prevent any cracks and ensure they are watertight.
126
3. Ferrocement
Ferrocement is cement mortar reinforced with chicken wire (or sometimes welded mesh). This
reinforcement gives strength and ensures water tightness. The smaller the meshes of the
reinforcement the better they prevent cracks in the mortar and, thus, ensure water tightness.
4. Fibre Reinforced Concrete
Fibre reinforced concrete is cement mortar reinforced with fibres. Short fibres which provide
the tensile strength are mixed with cement mortar. Then the mixture is formed into diverse
shapes like roofing sheets, pipes, etc.
The fibres used can be fibres from plants, like sugar cane, coconut, or sisal, or asbestos
fibres. Asbestos is found in underground deposits. The mining and production of asbestos is
very harmful to the health of the workers involved. Therefore, the use of asbestos should be
avoided.
G) Mixtures
For good concrete, the ingredients must be in the right proportions. For example,
cement : sand : gravel = 1 : 3 : 4
That means:
Mix one part cement with three parts sand and four parts gravel.
We say that the amounts are in the ration 1 to 3 to 4.
Cement is always given as the first figure with 1.
Accordingly, if you need more concrete, you can mix:
1 x 2 = 2 buckets cement
3 x 2 = 6 buckets sand
1
1
= 1 buckets cement
2
2
1
1
3 x 1 = 4 buckets sand
2
2
1
4 x 1 = 6 buckets gravel
2
1x 1
or
4 x 2 = 8 buckets gravel
and still have the same proportion (= ratio).
The most important mixtures are:
Ratio
1:2:4
1:3:4
1:4:3
1:4:6
1:0:4
1:2
1:4
1:8
Concrete/Mortar
watertight concrete
very strong concrete
easily workable concrete
ordinary concrete
porous concrete
very strong mortar
strong mortar
ordinary mortar
for
water tank
concrete rings for wells
latrine slabs
foundation, etc.
filter rings
ferrocement
surface of well platform
plastering
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6.7 Bricklaying
The most basic skills of brickwork, necessary for a water supply technician, are compiled
here. They consist of building “half brick walls” and “one brick walls” necessary for compost
latrine construction. Obviously, a fully trained bricklayer needs to know much more than is
presented here.
A) Bricks
Bricks are made from fired (= burnt) clay. Clay soil is mixed with sufficient water; the mould is
wetted; the clay is pressed into the mould; the surplus is removed, then the mould is
removed. When dry, the brick is fired in a kiln.
The quality of hand-made bricks can vary a lot. It depends on the type of clay, the quality of
manufacturing, the curing and the firing. The quality can be affected in the following ways:
1. Size: great variatons in size
2. Shape: curved bricks
3. Strength: easily breaking or crumbling bricks
It is an art to build straight and strong walls even with bricks of poor quality.
B) Mortars
Mortar is a composition of certain materials, used for the bedding and connecting of bricks in
a wall. Mortar consists of the “body” (= aggregate), which is sand, the “binding” material,
which is lime or cement or silt, and water.
1. Type of Sand
There are two varieties of sand: sharp and loamy. “Sharp” sand has sharp-cornered or
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angular grains, like this:
Mortar from sharp sand alone has great strength, but is not easy to work with.
“Loamy” or “soft” sand has rounded grains like this:
Mortar from loamy sand alone is weaker than mortar from sharp sand.
It is sticky and tends to hang to the trowel like glue. Sometimes, loamy sand tends to be
clayey (i.e. has a clay content), and this type must not be used.
The best aggregate for a bricklayer’s mortar is a mixture of sharp an loamy sand.
2. Proportion of Mixture
If hard, dense bricks of very low porosity and high crushing strength are to be used, then a
dense mortar (1:3) is suitable. If porous bricks of low crushing strength are to be used, then a
lower grade mortar is suitable. (If a dense or strong mortar is used in conjunction with a
porous type of brick, the mortar bed tends to shrink away from the bricks, leaving cracks.)
3. Amount of Water
The amount of water needs to be determined by experience, taking the temperature of the
day into account. The mortar needs to be sufficiently fluid to allow the spreading on an even
bed. Too much water, however, reduces the strength of the mortar.
C) Terminology
Special vocabulary is used in the bricklaying trade. Some words are explained here:
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stretcher:
header:
half-brick wall:
one-brick wall:
1
bat:
2
brick which is laid parallel to the wall
brick which is laid across the wall
wall with the thickness of half of the length of a brick, built from stretchers
only
wall with the thickness of the length of a brick, built from stretchers and
headers.
cut brick of this shape:
3
bat:
4
cut brick of this shape:
closer:
cut brick of this shape:
D) Measurements
In Sudan, you find bricks of many different sizes. However, the standard size is:
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220 mm x 100 mm x 60 mm
or
22 cm x 10 cm x 6 cm
20 mm are allowed for the thickness of the vertical mortar joint, 15 mm for the horizontal
mortar joint. The space the brick occupies in a brickwall including the mortar joints is called
nominal size. It is:
240 mm x 120 mm x 75 mm
or
24 cm x 12 cm x 7.5 cm
The size of bricks is standardized in such a way that stretchers and headers can easily form a
one-brick wall. Two stretchers in a wall with mortar in between are as wide as one header:
width of one brick:
width of one brick:
width of mortar joint:
length of one brick:
10 cm
10 cm
2 cm
22 cm
In height, 4 rows (= courses) of bricks must equal 30 cm. Each course must equal 7.5 cm.
Measure always from/to the top of a brick in a course.
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Four courses to 30 cm!
4 x 6 cm =
4 x 1.5 cm =
24 cm
6 cm
30 cm
Along the wall, 5 stretchers with their joints must equal 120 cm = 1.20 m
Five stretchers to 120 cm!
5 x 22 cm =
5 x 2 cm =
110 cm
10 cm
120 cm
To determine how many bricks make up a wall, divide the length of the wall by the nominal
length of the brick. Small differences can be balanced by increasing or decreasing mortar
joints sizes. These measurements are valid for bricks which keep more or less to the standard
size and shape. For high quality bricks which keep more exactly to the standard size, the
mortar joint may be only 1 cm thick.
D) Bonding of Brickwork
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To maintain strength, bricks must be lapped one over the other in successive courses. A
quarter-brick lap is called “quarter-bond”, a half-brick lap is called “half-bond”. If the lap is
greater or smaller than these, both appearance and strength are affected. If bricks are so
placed that no lap occurs, then the “cross joints” (= vertical joints) are directly over each other,
and this is called “straight joint”. An “external straight joint” appears on the face of the wall; an
“internal straight joint” occurs inside the wall.
If no closer is inserted, straight joints, either internal or external, occur:
In the following, the bonding of half-brick wall (= stretcher bond) and one-brick wall (= English
bond) shall be discussed only. These two types are mostly used in hot climates. The bonding
of a one-and-a-half-brick wall (occuring in cold climates) is much more complicated.
For each type of wall we need to know how to build
- the straight wall,
- a stopped end (for doors and windows),
- a corner,
- a T-joint (= cross wall).
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The basic rules of bonding are:
1. Avoid external straight joints at all times and
2. Avoid internal straight joints wherever possible.
3. Use whole bricks wherever possible.
Applied to the different types of bonds and walls this leads to specific rules:
1. Half-Brick Wall in Stretcher Bond
Half-brick walls are built in stretcher bond, consisting entirely of stretchers. Keep to the
following rules:
1. Maintain half-bond at all times (except T-joints).
2. No bats are necessary for a corner.
3. Use half-bats for a stopped end.
4. Use 2 three-quarter bats for T-joints.
First Course
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Second Course
Front View
Isometric View
If the first two courses have been set out correctly, they repeat themselves, and the vertical
joints in every other course will be upright or “plumb”. The bricklayer checks this by plumbing
the vertical joints at every 90 cm or so, along the wall.
2. One-Brick Wall in English Bond
One-brick wall can be built in English or Flemish bond. The latter will not be discussed here.
English bond consists of alternate courses of headers and stretchers. It is a very strong bond
without any straight joints.
Keep to the following rules:
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1. Maintain quarter-bond at all times.
2. A closer (= a brick cut half along its length) must follow the corner header.
3. A closer must follow the last header of a stopped end.
4. A closer must follow the stretcher of a T-joint.
5. In every change of direction on the same course the bond changes from stretcher to
header and the other way round.
First Course
Second Course
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Front View
Isometric View
The first two courses repeat themselves when you continue to build the wall.
3. Broken Bond
If the length of a wall does not fit to brick size, a cut brick must be inserted somewhere in the
length of the wall to make up its size. The cut brick should not be less than half-brick. The
usual procedure is to set out the correct bond from each end of the wall, placing the broken
bond as near the centre as possible. However, if there is little difference, the increasing or
decreasing of mortar joint sizes will often allow complete bricks to be used.
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E) Craft Operations
Some techniques on how to do good brickwork are explained here.
1. Basic Principles
Two basic principles help to do good brickwork:
1. Never allow quality to be sacrificed for speed.
2. Maintain general cleanliness.
Especially the beginner should never allow quality to be sacrificed for speed which will be
attained by constant practice. Never allow brick rubble and mortar droppings to collect under
your feet. A clean working place, clean mortar board and general cleanliness are important.
Mortar should never be allowed to harden on the blade of the trowel, as this creates a rough
surface and prevents free and easy movements when picking up and spreading mortar. Clean
all tools after work. Your working place should be organised: piled bricks and mortar at a
convenient distance.
2. Operation
The main bricklaying operation is spreading the mortar to an even bed. This needs practice
and a keen eye. Always wet bricks before laying them by dipping them into a bucket of water.
This will wash off surplus dust and prevent undue absorption of moisture from the mortar bed.
Do not grasp the trowel as if clenching the fist, but place the thumb on the handle lightly so
that a flexible wrist action is possible. Pick up the mortar with an easy sweeping motion and
spread it on the wall sufficiently thick to allow the brick to be placed by pressure of the hand.
Do not place too much mortar under the brick, because this will require considerable
hammering before the brick reaches its final position.
Method of grasping the brick-trowel
If bricks are curved, it is difficult to keep a flat surface of the wall and to prevent “hatching and
grinning”.
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If bricks are curved, lay them always with the curve upwards like this:
Never lay them with the depression upwards, because this makes the laying of the next
course difficult:
3. Keeping to Measurements
Normally, corners are erected ahead of time before building the walls. First, erect
approximately six courses of brickwork at the corners. Make sure that the corner is plumb by
using the spirit level or plumb bob. Use a straight edge to make sure that the wall is in
alignment. Make sure that the thickness of the courses is kept by a gauge peg. The wall itself
is to be racked back.
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Building for level:
Then use a line and pin for building the straight walls or use two wooden corner blocks.
Use of line and pin:
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Use of wooden corner blocks: wooden corner block
When laying bricks along a line, always ensure that a trace of daylight can be seen between
the line and the brick. This prevents the laying of the bricks too hard to the line. To keep the
wall flat (= to prevent hatching and grinning), imagine laying the outside surface of the brick
parallel to the line and the edge of the last course. Watch out for this even if it means that the
surface of the course is not level.
If the bricks are of uneven shape, only one side of the wall can be built flat, either inside or
outside.
6.8 Improved Local Building
The technologies on how to build
are widely known and are not
improvements are compiled here,
a mudblock house. Select the
conditions.
with local materials like poles, earth, bamboos, grass, etc.
to be described here. However, some suggestions for
both for a house constructed from poles and earth, and for
suggestions which are possible and suitable for your
A) Measures without Additional Costs
1. Build your house, especially a two-room house, in an East-West direction. The rising and
the setting sun should shine on the smaller walls. The sun should never shine on the longer
walls. This will make your house cooler.
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2. If possible, build your house with a shade-giving tree on the eastern and/or western side of
the house
3. Plant trees on the east and west sides of your house.
4. Cut the poles and bamboos in dry season.
5. Choose ant-resistant types of wood.
6. Store them in an elevated place, not directly on the ground.
7. Before building, check the mud with the following tests:
a) Sedimentation Test
- Take a transparent glass jar of one litre or more with a sufficiently wide top opening; it must
be cylindrical with a flat bottom.
- Fill the jar upto one quarter of its height with the soil to be used for building.
- Add clean water up to the top of the jar.
- Close the jar with your hand and shake it well until water and soil are thoroughly mixed.
- Put the jar on a level surface.
- After one hour, shake the jar well and put it on a level surface again. Now the jar must be left
untouched without any movement.
- After 45 minutes, you can measure the thickness of each of the different layers and compare
each with the total thickness of all the soil in the jar. This gives you the percentage of the
amount of gravel, sand, clay, and silt in the soil.
- Soil suitable for building should consist of at least 33% sand and between 5% and 30%
clay/silt. If the soil is not suitable, add sand or clay accordingly. A good mixture for example
would be
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b) Compaction Test
- Take a handful of dry, screened (= sieved) earth and moisten it until it is damp enough to
form a ball. It should not be so damp that it will leave more than a slight trace of water on your
hand.
- Drop the ball from the height of your shoulders onto hard ground. If the ball breaks into a few
smaller pieces, the mixture is all right. If it breaks into many pieces, it contains too much sand.
If it does not break into any pieces, it contains too much clay and silt for building.
8. Build with mudblocks, if possible.
9. If you build with mudblocks, build a foundation either of mudblocks or of stones.
10. Build the inside floor 10 cm higher than the ground level outside.
11. Mix sand or the soil of anthills or cow dung or merissa residue into the mud for smearing
floor and walls.
12. Plaster the walls and use a trowel to smear the floor.
13. Keep all fresh mud work out of the sun.
14. Provide enough ventilation.
15. Leave sufficient space between wall and roof in order to be able to clean the termites
away.
16. Fix old tins between the wall and the roof truss to hinder the termites.
17. Protect the wall bottom from being washed out as illustrated in this drawing:
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18. Dig a drainage ditch around your house, if necessary.
19. Smear and repair the house frequently. Especially, repair cracks immediately, if possible.
B) Measures with Additional Costs
1. If you build with poles and earth, build the structure for the roof separately from the walls.
The poles should not touch the walls at any point in order to control termites.
2. If you build with mudblocks, build an ant course from concrete with two layers chickenwire,
5 cm thick. It is extremely important, to keep the concrete wet for 7 days to prevent cracks
which would allow termites to penetrate (see 6.6/7).
Alternatively, you can use bituminous foil or flattened zinc sheets for an ant course. They
must be 10 cm above floor level and folded at the joints.
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3. Build the walls higher than in the traditional way.
4. Build big windows with shutters on the opposite side of the building.
5. Fix mosquito screening between walls and roof.
6. Thatch with the improved thatching method which builds a roof with a continuous surface
without steps. This method requires about 507. more grass, but lasts many years longer.
More information is available from the Support Unit, Community Development Department,
Juba, or from the literature.
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7. Building Administration
7.1 Planning
Realistic planning is essential for properly organizing the work and to avoid confusion and
disappointment of communities and owners. Planning helps to streamline one’s efforts, to
prepare everything in time for the work, and to avoid unnecessary delays. However, planning
should be a helpful tool, not a rigid principle to enforce. Therefore, plans should be made and,
if necessary, altered according to circumstances. Having to alter your plans should not
discourage you from doing any planning at all. The benefits of regular planning will show in
the long run.
Planning of construction work is best done in four steps: checking the resources needed,
timing, filling the diary, and preparing lists of materials and equipments.
A) Checking the Resources Needed
When you plan practical construction work, always use the following check list:
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Carefully check all these points:
- Did all parties agree on the work to be done?
- Are the technical plans (drawings etc.) ready?
- Is skilled labour available?
- Is unskilled labour available?
- Is supervision possible?
- What materials are needed? Are storage facilities available on-site?
- What equipment is needed? Are storage facilities available on-site?
- Is water available and ready?
If any of these elements is not available in sufficient quantity, the work can not run smoothly.
B) Timing
The timing of building work is done mostly with what is called a “bar chart”. The sequence of
work mostly depends on the first two “fingers”, i.e. “Are agreement and technical plans
ready?”, and “Is the labour available?”
The form, “WORKPLAN”, is for bar chart planning for the whole project for one month. It is to
be used as follows:
WORK PLAN
DATE
WORK
PLANNING
Fill in the department, month and year.
Check on which day the first of the month falls; if it is a Wednesday for
example, write 1 below We, 2 below Th and 3 below Fr. Sa and Su would be
the 4th and the 5th, so write 6 below Mo, 7 below Tu and so on. Cross out
any public holiday.
Write the different work to be done, e.g. latrine No.12, latrine No.13, well
No.7, work in the workshop, etc. Only work which takes several days to
complete should be recorded.
Mark the days planned for working on latrine No.12 with crosses in pencil,
e.g. XXX. If you have two teams who can work parallel, work can overlap.
Otherwise, the work on the next latrine, No.13, can only start after No.12 has
been finished. In the bar chart, it will look like this:
XXXXX
XXXXX
XXXXX
The time needed for certain work to be completed is to be estimated
according to experience. Plan sufficient time for cleaning and for working in
the store, etc.
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RECORDING
It is advisable to use the same form for recording actual work done as well.
For example, mark the days on which work on a certain latrine actually took
place with red boxes:
The work records have to be entered daily. Thus it will become clear whether
or not the timing and the estimated duration of work were correct.
The planning and the filling in of the WORK PLAN is done by the project management team.
A copy can be given to the foreman or to the technicians, to be fixed on a noteboard in the
workshop.
C) Filling in the Diary
After the overall timing has been fixed, the work is to be planned in detail. Check the last
three “fingers” - that is, materials, equipment, and water - and decide when you have to make
them available on site according to the bar chart.
Fill in your diary under the appropriate date; for example,
- transport of 5,000 bricks to site,
- transport of six drums water to site,
- transport of building box, etc. to site,
- (instruct, tell) labourers to report to site tomorrow,
- etc.
D) Preparing List of Materials and Equipment
Write lists of materials and equipment needed, either directly into your diary or on separate
sheets. The list shall contain all materials and equipment with their quantities.
E) Planning Work for a New Site
Beside the planning as described in A to D, specific planning is necessary before starting
work on a new site. Consider the following aspects:
- Where can materials be stored on-site or as near as possible?
- Where can equipment be stored on-site or as near as possible?
- Where can the staff get accomodation (for far-away sites)?
- Which means of transport can the staff use (for near sites)?
- What are the arrangements for feeding?
- How shall communication be kept up between the staff and the office?
For a big building task it is necessary to draw a site plan containing the following:
- the boundaries of the construction site,
- the connection to roads,
- location and size of existing buildings,
- vegetation on site (trees, etc.),
- storage facilities for materials,
- storage facilities for equipment,
- staff accomodation,
- feeding place,
- the north direction,
- the slope of the area,
- eventually necessary drainage channels.
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Sudan Council of Churches/Munuki Water and Sanitation Project
WORK PLAN
Department/Area: WATER SUPPLY
Month: JULY
Year: 1987
7.2 Work Records
Daily work records are essential, for the following reasons:
1. for the final cost calculation after completion of the well, latrine, etc.;
2. for future estimations of the number of labourers and amount of materials necessary;
3. for deciding if the concrete has already cured enough for further steps;
4. for settling any disputes that may develop with the community or the owner.
Keeping the Work Records
The work records are to be kept by the foreman or technician responsible on site. He/she has
to keep the “WORK RECORDS” form (preferably in a protecting plastic envelope) on site with
the tools, and has to enter records daily. After completion of the on-site work, the work
records are to be handed in to the office for filing.
The work records are to be filled in as follows (see 7.2/3f; 7.4/5f):
WELL No. or
LATRINE No.
DATE
SCC STAFF
LABOURERS
COMMUNITY
WORK
The number of the well or latrine and the name of the community or owner
and location need to be recorded.
There is one entry for each day.
The project staff are to be listed with the abbreviations of their names.
The total number of the labourers in the community or the owner present
during the whole working day in accordance with the leader of the
community workers is to be recorded, including the people caring for food.
The type of work is to be put into numbers, if possible, e.g. casting 1
concrete ring, ∅ 1.07 m, filter type; digging 0.6 m; etc.
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CEMENT
SAND/GRAVEL
MIXTURE
OTHER
MATERIALS
WATER TABLE
WELL
BOTTOM
SOIL
REMARKS
Can be recorded in number of buckets or bags.
To be estimated in number of buckets.
The ratio of the concrete or mortar mixture is to be recorded; e.g., 1 : 3 : 4
(Cement: Sand: Gravel) (see 6.6/13f).
All other materials are to be quantified; e.g., 6 m reinforcement ∅ 6 mm, 1
pc welded mesh, 1 handpump body, 400 bricks. Do not forget small
materials like padlocks, handles, etc. Do not forget materials provided by
the community, like poles, etc.
Each morning, the water table should be recorded, in metres from ground
level, in order to check the yield of the well during the night.
The records kept of the depth of the well indicate the progress of the
digging work.
The soil type (like whitish clay, sand, clay with gravel) along with all
changes in the soil type, need to be recorded. This helps for later
evaluation of the soil conditions. For recording the soil conditions in a well
you can also use the form, “SOIL PROFILE”, on 8.13/9.
Special events can be recorded here, especially damage to equipment,
technical problems, conflicts with the community or owner, etc.
Sudan Council of Churches/Munuki Water and Sanitation Project
150
WORK RECORDS - WELL NO ...
Date
SCC
Staff
Labourers
Community
Work
Cement
Buckets
Sand
Buckets
Gravel
Buckets
Mixture
Other
Material
Water
Table
Well
Bottom
Sudan Council of Churches/Munuki Water and Sanitation Project
WORK RECORDS - COMPOST LATRINE NO ...
Date
Staff
Work
Cement
Buckets
Sand
Buckets
Gravel
Buckets
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Mixture
Drums of
Water
Other
Materials
Remarks
Soil
Remarks
7.3 Records of Materials
The materials needed for the construction of a well (or any other construction) should be
summarized after completion of the work. This is the task of the foreman or technician
responsible on site-Records of materials are not necessary for standard compost latrine
construction, because the materials needed are always the same.
The following principles should be observed:
- Evaluate the daily work records, add up all materials consumed and fill in the sum on the
“COST CALCULATION” form (see 7.3/2; 7.4/1).
- Start with the bulky items like cement (to be recorded by number of bags), reinforcement,
sand and gravel (to be recorded in lorry loads or m3).
- End the list with the smaller items like padlocks, handles, manhole covers, etc.
- Fill in whether the materials were contributed by the community or by the project (SCC).
- Do not forget local materials contributed by the community.
- After filling in, hand the form to the storekeeper. The storekeeper has to check to see if
the recorded materials are in accordance with his/her records in the store. The
storekeeper fills in the prices according to the stockcards. The price of small items with
unknown value can be estimated.
- Afterwards, the records of materials are handed to the office for final check, final cost
calculation and filing.
Sudan Council of Churches * Munuki Water and Sanitation Project
152
COST ESTIMATION/CALCULATION FOR ......
No.
Quantity
Unit
Item
Unit Price
Total
Contributed by
7.4 Cost Calculation for Community Work
Lk 14,28-30
After the completion of a construction work such as a well, compost latrine, etc., a final cost
calculation needs to be made for assessment of the work done and for paying the bills.
A) Form for Cost Calculation
For any cost calculation the form, “COST ESTIMATION/CALCULATION”, should be used. It
should be filled in as follows:
COST
ESTIMATION/
COST
CALCULATION
FOR
NO
QUANT
UNIT
ITEM
The form can be used either for cost estimation before the work has
started, or for cost calculation after the work has been completed.
Underline, which purpose you will use the form for and cross out the
other.
Give the full information about the well/latrine with its number, location,
owner or community.
Number the items 1,2,3,...
Record here the quantity, i.e. only the figures without the unit. If the item
cannot be quantified, write “div.” (= diverse).
Record here the unit. Possible units are:
bags
for cement
m
for reinforcement, rope etc.
pcs
for pipes
kg
for nails
gal
for fuel
working days
for labour
km
for transport
Record here the items clearly and unmistakably.
Write for example:
instead of “reinforcement”
reinforcement ∅ 6 mm
instead of “pipe”
metal pipe ∅ 2”, 3 m
instead of “rope”
nylon rope ∅ 10 mm
instead
of “nails”
1
nails 2 “
2
UNIT PRICE
TOTAL
CONTRIBUTED
BY
diesel, petrol
instead of “fuel”
unskilled or skilled labour
instead of “labour”
transport with Toyota pickup
instead of “transport”
Record the price of one unit in £S; i.e., the price of one bag of cement,
one kg of nails, one working day unskilled labour, one km driven by the
Toyota pickup, etc
Multiply the QUANTITY by the UNIT PRICE. This gives the TOTAL for
the particular item.
Record whether the item has been contributed (i.e. paid or provided) by
the community or by the project (SCC), or by another agency,
government office, etc.
153
After filling in all the items, draw a line under the column “TOTAL” and add up all the TOTALs.
The sum is the GRAND TOTAL, the whole amount spent on the work.
B) Steps of Cost Calculation
The cost calculation itself should be done according to the following steps (for example see
7.4/4-11):
1. Collect the “WORK RECORDS” from the foreman or technician in charge on the site.
2. Collect the “RECORDS OF MATERIALS” from the storekeeper.
3. Divide the expenses into:
A) MATERIALS
B) LABOUR
C) TRANSPORT
D) PLANNING AND SUPERVISION
E) DEPRECIATION OF EQUIPMENT
4. Record first the material costs:
Write the heading “A) MATERIALS” on the form “COST CALCULATION” under “ITEMS”.
Start by recording the materials below. Record local materials like sand, gravel, and poles.
Include the price for transportation and loading if you have paid for “lorry load delivered at
site”. If you have paid separately for transport and loading, record these costs under
“TRANSPORT” and “LABOUR”. Record also materials which were not paid for but contributed
freely. Estimate their costs and record who contributed them. If work was done in the
workshop on some material, record it here also and estimate the costs, e.g. “welded
adjustment on handpump body”. These costs belong to the material itself. Record all store
materials like cement, reinforcement, etc. Do not forget small items. After recording all
materials, add them up for a "TOTAL for MATERIALS".
5. Next, record the labour costs:
Write the heading “B) LABOUR COSTS” on the form under “ITEMS”. Count the number of
working days from the WORK RECORDS. Record unskilled and skilled labour separately.
The “UNIT PRICE” for daily paid labourers is their daily wage; for permanently employed staff
it is their gross salary divided by 20 (Each staff works about 20 days per month if we take into
consideration absences due to sickness, leave and holidays).
Record also unskilled labour provided by the community (to be counted from the WORK
RECORDS), including the time spent for cooking for the staff, etc. Estimate the “UNIT PRICE”
according to the market price for unskilled labour.
After recording all labour, add them up for a “TOTAL for LABOUR.”
6. Record the transport costs:
Write the heading “C) TRANSPORT” on the form under “ITEMS”. Check in the logbook to see
how often the car went to the particular site and then add up the km. For example, record
them as “350 km, Toyota pickup”. The “UNIT PRICE” for each km driven is to be found in the
annual report of the previous year. In the annual report the total costs including depreciation,
fuel, maintenance, insurance and driver of the vehicle are calculated and drawn down to each
km; for example, the price per km for a Toyota pickup is presently £S 1.750 m/ms (1987). For
calculation of the cost per km see 3.4. If a lorry was hired on a daily basis from Logistics
Department, record the hiring costs per day; for example: “3 days lorry”, the “UNIT PRICE”
being the hiring cost per day.
154
After recording all transport costs, add them up for a “TOTAL for TRANSPORT:1
7. Record the costs for planning and supervision:
Write the heading “D) PLANNING AND SUPERVISION” on the form under “ITEM”. These
costs cover the planning work in the office and the supervision on site. They can be either
roughly estimated as a fixed sum (no “QUANTITY”, “UNIT”, “UNIT PRICE” given, just the
“TOTAL”), or as a percentage of the total costs. Alternatively, the working days of the senior
staff can be counted.
Add up all the costs for a “TOTAL for PLANNING AND SUPERVISION.”
8. Record the costs for depreciation of the equipment:
Write the heading “E) DEPRECIATION OF EQUIPMENT” on the form under “ITEM”. This will
cover damages and losses of equipment, and the fact that all equipment needs to be replaced
after a certain time. Normally these costs are estimated as a fixed sum and this is then
recorded as the “TOTAL for DEPRECIATION OF EQUIPMENT.”
9. Summarize all the expenses in the form, “SUMMARY OF COST CALCULATION FOR
COMMUNITY WORK” (see 7.4/11).
Fill in the costs of material, labour, etc. Add up all the costs. The sum, called “TOTAL
COSTS”, is the real complete costs of the well/latrine which was built.
Calculate the percentage of the total spent on each heading, from A) to E).
Add up all the percentages. The sum must be 100%; otherwise, look for a mistake.
10. Add up all the contributions of the community/owner in your cost calculation and enter it
into the summary. Add up all contributions of the project (SCC). However, if SCC has
received cash payment, that means that part of the expenses of SCC has been replaced and
that only the remainder is the real contribution of SCC. Therefore, the sum of all amounts
contributed by SCC is the expenses of SCC. The cash paid to SCC should be deducted. The
result is the contribution of SCC. Enter it into the form. Add up and fill in eventual
contributions from others.
Now add up all the contributions. The sum must be equal to the TOTAL COSTS of step no.9,
otherwise look for a mistake. Calculate, what percentage each contributor has given. Add up
all percentages, the sum of which must be 100%; otherwise look for a mistake.
11. Present the summary to the PMT, the Finance Department, the Programmes Department
and the owner or community, if necessary. These summaries are important for comparison
purposes and for future decision-making.
12. If there are still payments outstanding, write a bill or payment request to the concerned
party and hand it over attached to the cost calculation.
C) Example for Cost Calculation (simplified)
1. Task
Do a complete cost calculation for a well which was built by the neighborhood community
Munuki and SCC Munuki. The well is located in Munuki West at the open space beside the
planned cinema. The details of the work are recorded on the attached form “WORK
RECORDS”. The prices of the different commodities are as follows:
155
2. Prices of Commodities Provided by SCC
1 pc
1 pc
1 pc
1 bag
1 working day
1 day
1 km
concrete ring ∅ 1.07 m
filter ring ∅ 1.07 m
well cover ∅ 1.07 with manhole
cement
skilled labour
hiring of lorry
Toyota pick-up
£S 311.500 m/ms
£S 311.500 m/ms
£S 700.000 m/ms
£S 115.000 m/ms
£S 10.000 m/ms
£S 200.000 m/ms
£S 1.750 m/ms
3. Prices of Commodities Provided by the Community
1 m3
1 m3
1 drum
1 bundle
1 pc
1 kg
1 pc
1 pc
1 working day
1 meal
sand
gravel
water
bamboo
pole
nails 2”
door for fence
padlock
unskilled labour
breakfast for one person
£S 35.000 m/ms
£S 65.000 m/ms
£S 2.000 m/ms
£S 15.000 m/ms
£S 15.000 m/ms
£S 15.000 m/ms
£S 100.000 m/ms
£S 15.000 m/ms
£S 5.000 m/ms
£S 2.000 m/ms
4. Additional Information
Breakfast was provided for all SCC workers and community workers on all working days.
According to the logbook, 60 km were driven by the Toyota pickup for transport of equipment
and supervision. Planning and supervision costs £S 600.000 m/ms. The well siting before the
construction of the well costs £S 100.000 m/ms. The depreciation of equipment (tripod, pump
and tools) costs £S 1,000.000, m/ms.
5. Cross Section of the Completed Well
156
Sudan Council of Churches * Munuki Water and Sanitation Project
WORK RECORDS - WELL NO...15
Date
SCC Staff
Labourers
Community
6
6
4
30.1
31.1
2.2
Jo/Si/Gl/P
3.2
same
4
4.2
5.2
6.2
same
same
same
4
4
4
9.2
same
4
10.2
same
4
11.2
same
4
12.2 same
4
Work
Cement
Buckets
digging
digging
transport
of
rings, cover,
equipment
lowering ring
+ digging
same
same
digging
digging and
lowering one
ring
lowering two
rings
backfill, cover
placed
platform
platform and
drainage
Sand
Buckets
-
Gravel
Buckets
-
Mixture
-
-
-
-
-
-
-
1
4
1
-
1:4
1
2
2
-
1:4
2 bags
18
24 b. +
2m3
1:3:4
3 bags
27
36
1:3:4
157
Other
Material
-
1 filter ring
∅ 1.07
same
same
1
fully
concrete
ring ∅ 1.07
2 above
1 cover
1
drum
water
1
drum
water
Water Table
3.00
Well
Bottom
1.80
3.00
3.00
Soil
3.00
3.50
3.00
3.00
3.00
4.00
4.30
4.60
3.00
5.00
sandy
clay
same
same lot of water
same Honda
pump used
same same
3.00
5.00
same
3.00
5.00
same
3.00
5.00
same
clay
clay
clay
Remarks
lorry hired
for 1 day
Sudan Council of Churches * Munuki Water and Sanitation Project
WORK RECORDS - WELL NO...15
Date
SCC Staff
13.2
Jo/Si/Gl/P
Labourers
Community
-
16.2
-
3
transport of
all equipm.
to workshop
and curing
build fence
17.2
-
3
build fence
Total
Work
6 bags
Cement
Buckets
-
Sand
Buckets
-
Gravel
Buckets
-
-
-
-
-
1.5 m3
Mixture
Other
Material
Water Table
-
3
drums
water
-
-
-
-
18 poles
1 door
1 lock
20
bdls
bamboos
4 kg nails 2 “
3 m3
158
Well
Bottom
Soil
Remarks
transport
by Toyota
pickup
Sudan Council of Churches * Munuki Water and Sanitation Project
COST ESTIMATION/CALCULATION FOR WELL NO 15 Neighborhood Community
Munuki West
No.
Quantity
1
6
2
3
4
5
6
7
8
9
10
11
1
6
1.5
3
5
18
20
4
1
1
pc
bags
m3
m3
drum
pcs
bdls
kg
pc
pc
1
2
3
40
54
94
days
days
pcs
B) LABOUR
skilled labour
unskilled labour
breakfast
TOTAL OF B) LABOUR
1
2
1
60
day
km
1
2
1
Unit
Item
Unit Price
Total
Contributed
by
311.500
1,869.000
scc
700.000
115.000
35.000
65.000
2.000
15.000
15.000
15.000
100.000
15.000
700.000
690.000
52.500
195.000
10.000
270.000
300.000
60.000
100.000
15.000
4,261.500
scc
scc
comm.
comm.
comm.
comm.
comm.
comm.
comm.
comm.
10.000
5.000
2.000
400.000
270.000
188.000
858.000
scc
comm.
comm.
C) TRANSPORT
big lorry
Toyota Pickup
TOTAL OF C) TRANSPORT
200.000
1.750
200.000
105.000
305.000
scc
scc
D)
PLANNING
AND
SUPERVISION
planning and supervision
well siting
TOTAL OF D) PLANNING
AND SUPERVISION
600.000
100.000
600.000
100.000
700.000
scc
scc
1,000.000
1,000.000
1,000.000
scc
A) MATERIALS
concrete rings ∅ 1.07 m (3
filter, 3 fully)
cover with manhole
cement
sand
gravel
water
poles
bamboos
nails
door for fence
padlock
TOTAL OF A) MATERIALS
E) DEPRECIATION
depreciation of equipment
TOTAL
OF
E)
DEPRECIATION
159
Contributions:
Contributions of SCC
1,869.000
700.000
690.000
400.000
200.000
105.000
600.000
100.000
1,000.000
5,664.000
Contributions of Community
52.500
195.000
10.000
270.000
300.000
60.000
100.000
15.000
270.000
188.000
1,460.500
5,664.000
1,460.500
Sudan Council of Churches * Munuki Water and Sanitation Project
SUMMARY OF COST CALCULATION FOR COMMUNITY WORK
Well/Latrine No.:
Community/Owner:
Site:
15
Neighborhood Community Munuki West
Munuki West, open space beside planned cinema
1. Costs Differentiated According to Type
A) Materials
B) Labour
C) Transport
D) Planning and Supervision
E) Depreciation of Equipment
Total Costs
£S
£S
£S
£S
£S
£S
4,261.500
858.000
305.000
700.000
1,000.000
7,124.500
= 60 %
= 12 %
=4%
= 10 %
= 14 %
= 100%
2. Costs Differentiated According to Contribution
A)
B)
C)
D)
Contribution of Community/Owner
= Expenses of Community/Owner + Cash paid to SCC
= £S 1,460.500 + £S 500.000
Contribution of SCC
= Expenses of SCC - Cash paid to SCC
= £S 5,664.000 - £S 500.000
Contribution of .....................
Contribution of .....................
Total Costs
=
= £S
1,960.500
= 28 %
=
= £S
£S
£S
£S
5,164.000
...............
...............
7,124.500
= 72%
= ... %
= ... %
= 100%
7.5 Cost Calculation for Contract Work
Cost Calculation for contract work is basically done in the same way as the cost calculation
for work on a community basis. However, there is no need for differentiation according to the
contributors, as all work is done by the contractor and the owner’s contribution is the
payment.
Follow these steps for calculation:
160
1. to 8. see 7.4, B)
9. Summarize all the expenses on the form “SUMMARY OF COST CALCULATION FOR
CONTRACT WORK”. Fill in the costs for materials, labour, etc. Add up all the costs. The
sum is the total of the expenses which were spent by the SCC as a contractor. Calculate
what percentage of the total was spent on each heading, A) to E). Add up all the
percentages. The sum must be 100%, otherwise look for a mistake.
10. Compare the expenses of SCC with the payments of the owner to SCC. Find out about
the payments from administration. If the expenses are higher than the payment, SCC has
worked at a loss. Fill in the difference under “LOSS”. Supplementary payments may be
requested from the owner. If the expenses are less than the payments, SCC has worked
with profit. Fill in the difference under “GAIN”. If the payment and the expenses are equal,
there is no loss or gain.
Cost estimations for future contracted work are done in the same way. However, the amounts
need to be roughly estimated. If the cost estimation was done on a realistic basis and no
items were forgotten, the total should be very close to the final cost calculation.
Sudan Council of Churches * Munuki Water and Sanitation Project
SUMMARY OF COST CALCULATION FOR CONTRACT WORK
Well/Latrine No.:
Owner:
Site:
.....................................................
.....................................................
.....................................................
Expenses of SCC
A)
B)
C)
D)
E)
Materials
Labour
Transport
Planning and Supervision
Depreciation of Equipment
Total Expenses
Expenses of SCC
Payment of Owner to SCC
LOSS (or subsidy) of SCC
GAIN (or profit) of SCC
£S
£S
£S
£S
£S
£S
............ =
............ =
............ =
............ =
............ =
............ =
... %
... %
... %
... %
... %
100%
£S ....................
£S ....................
£S ....................
£S ....................
7.6 Purchasing Locally
To keep to a certain procedure of purchasing items from the local market will help to save
time and efforts and money and to prevent losses.
Follow these steps:
1. Write a complete, quantified and exact purchase list and discuss it with colleagues and the
storekeeper who may add something-It is very annoying to have to repeat the whole
purchasing procedure when a single item has been forgotten.
The list needs to be sorted; that is, items to be purchased from the same shop should be
listed together (e.g., tools together, stationary together, etc.).
Fill in all the items on the following list:
161
No.
Quant.
Unit
Item
Shop1
Unit Price
Shop 2 Shop 3
Total
Shop 4
Alternatively, the “COST CALCULATION” form can also be used for the purchase list (see
7.3/2).
2. Collect pro forma invoices for the items in the desired quantity. If the item is expensive,
collect invoices for the same item from several shops, if possible. Fill in the given prices on
the list.
3. Choose the cheapest source or the best quality, underline it on the list and calculate the
totals using that figure. Add up the totals.
4. Write a payment request for the total amount, get it approved by the chairperson of the
PMT and present it to the accounts office with the pro forma invoices attached.
5. Collect the money. Sign for receiving it (for your own protection). Keep the money in a safe
place; for example, in a closed bag. Do not mix it with private money.
Alternatively, you can collect money from the petty cash of the project if you need only a small
amount. Take care that the amount, the date and your name are recorded.
6. Purchase the items in the respective shops. Check the quality (e.g., tools operating?, bags
not torn?, parts not broken?, timber straight?) Do not accept the item if it is not of good
quality. Check the quantity. Count all pieces by yourself. Ask for appropriate packing. Load
everything carefully.
7. Pay for the items against an invoice (= receipt). Check to see that the amount is the same
as on the pro forma invoice. Carefully count the change. Record any payment immediately on
a prepared sheet of paper; that is, as soon as you leave the shop. It is very easy otherwise to
forget a payment and to get confused. If you cannot get a receipt (e.g. at an open market),
write a receipt yourself in the receipt book and let the shopkeeper sign, if necessary with a
finger print. If you have no receipt book at hand and the amount is small, record it and the
receipt can be written in the office.
Calculate the balance. The balance must be equal with the money left with you. Thus you can
check the money at any time.
Money received:
Shop
First shop
Second shop
....
Payment
25.000
107.000
£S 300.000 m/ms
Balance
275.000
168.000
8. Put all the receipts immediately together into a separate envelope (not just into your
pocket).
9. Transport all the items to the store and hand them over to the storekeeper.
The items need to be recorded on the stock cards including the prices. It is important to
record the prices at this point, because the receipts are going to be handed to the accounts
office.
162
10. In the end of every purchasing day, count the money left with you and compare it with the
balance according to your records. If it does not fit, look for a mistake.
11. If receipts are written in Arabic, write the quantity, item and amount on the receipt in
English.
12. When you have finished purchasing and have spent all, or almost all, of the money,
number all the receipts 1,2,3, etc. Write on each receipt the budget No. under which the
receipt shall be recorded. Summarize the receipts on a separate sheet of paper as follows:
Cheque No:
Date:
Amount:
47812
3.2.87
£S 300.000 m/ms
No
1
2
3
Receipt No.
1
2
Date
5.2.
6.2.
...
Budget No
4.2
3.2
Item
hammer
stationary
Amount
25.000
107.000
Balance
275.000
168.000
For the budget numbers see 2.9/1.
13. Collect all the receipts and an eventual balance and hand it over to the administration, so
that they can register it in the finance book and hand it over to the accounts office.
7.7 Purchasing from Khartoum
Purchases inside Sudan, especially from the capital, can be arranged through the Logistics
Department of SCC.
163
The procedure is as follows:
1. Write a complete, quantified and exact purchase list. Each item needs to be described
unmistakably. Mention the quantity, the unit, the item itself, the material, the measurements
(like 0, length, etc.). If necessary, add pictures or refer to a catalogue. Discuss and decide
upon the purchase list with your colleagues and the storekeeper.
No.
Quantity
Unit
Item
Remarks
Let this purchase list be typed in three copies. Check afterwards thoroughly for spelling and
typing errors.
2. Write a letter to the Logistics Department in Khartoum, requesting them to purchase and
send the items according to the attached purchase list. Send the original to Khartoum,
Logistics Department, and a copy to the Finance Department with a note that they should
kindly make the money available.
The third copy remains with the project and is to be filed in the respective paper file (e.g.,
“tools”, “pump”) or in the paper file “RUNNING ORDERS”.
3. Fill in the order on the chart “RUNNING ORDERS” hanging in the office. This helps to
follow up outstanding orders.
4. From time to time, inquire about the order by radio message ot letter.
5. When receiving the items, compare the waybill and the purchase list and the items actually
received. If everything is correct, sign the waybill. Note missing or damaged items on the
waybill (all copies).
6. Put all the items into the store and hand them over to the storekeeper. The items need to
be recorded on the stock cards.
7. If there is any difference between the purchase list and the items received, write a new list
headed “ITEMS RECEIVED”.
8. Send the list “ITEMS RECEIVED” and an accompanying letter to Logistics, acknowledging
receipt of the items and thanking them. Ask for the invoices and transport costs.
9. Alternatively, inquire from the Finance Department about payments made.
10. After receiving the information about payments, tell the administration to record them into
the finance book.
11. Divide the transport costs accordingly on each item.
Example:
No
Quant
Unit
1
2
3
20
5
30
pcs
gal
pcs
Item
zinc sheets 8’
oil paint, green
buckets
PURCHASE COSTS
Transport by air Khartoum -Juba
Loading/unloading
TOTAL COSTS
164
Unit Price
Khartoum
60.000
55.000
15.000
Total
Khartoum
1,200.000
275.000
450.000
1,925.000
800.000
40.000
2,765.000
Unit Price
Juba
86.400
79.200
21.600
The TOTAL COSTS are the PURCHASE COSTS plus all other costs of transport, handling,
loading, etc.
The TRANSPORT FACTOR is used to include all additional costs, thereby finding the real
cost of each item.
TRANSPORT FACTOR =
TOTAL COSTS
£S 2,765.000
=
= 1.44;
PURCHASE COSTS £S 1,925.000
Multiply each “Unit Price Khartoum” by the TRANSPORT FACTOR. The result is the “Unit
Price Juba” which includes all transport and other additional costs.
Note, that the price including transport, etc., is considerably different from the purchase price.
12. Record the “Unit Price Juba” on the stock cards.
7.8 Purchasing from Abroad
Some items are not available within the country and, therefore, need to be purchased from
abroad. Purchases from abroad differ considerably from purchases within the country,
because foreign currency payments and customs clearance are necessary.
Some items from abroad can be purchased by the Logistics Department. In this case the
procedure is similar to “Purchases from Khartoum”. However, the purchasing of special
technical items, like specific tools, pumps, hand augering equipment, etc., require special
technical knowledge and information about the project’s needs. Therefore, these orders need
to be handled by the project staff themselves in cooperation with the Logistics Department.
The procedure is basically as follows, but it may vary on different occasions:
1. Write a complete, quantified and exact purchase list and discuss it with colleagues and the
storekeeper.
2. Write a letter to the supplier(s) requesting a pro forma invoice. Describe the items you want
exactly. If possible, request pro forma invoices from several suppliers.
3. Upon receival of the pro forma invoices, check them and select the most suitable.
4. Discuss in the PMT and check with the administration whether the money is available in the
budget. If necessary, get approval from the Deputy General Secretary or the Finance
Director.
5. Write a letter to the supplier ordering the items according to his or her pro forma invoice.
Indicate how the items should be packed and transported to your end (by air, by ship, etc.), by
which route and by which transport company, if known.
Send copies of this letter to the Deputy General Secretary, Finance Director, Logistics
Department in Khartoum/Juba, and to the transport company. One copy remains in the
project and is filed in the respective paper file (according to subjects, with a separate file for
each type of equipment).
6. Write an accompanying letter to Logistics Department in Khartoum requesting them to
obtain an import license for this order.
7. Fill in the order on the chart “RUNNING ORDERS”, hanging in the office.
8. From time to time, inquire about the order by telex or letter.
165
9. After notice that the items have arrived, ask Logistics Department for assistance in customs
clearance.
10. Check the items and compare them with the waybill, with the order, and with the pro
forma invoice. If everything is correct, sign on the waybill. Note items missing or damaged on
the waybill (all copies).
11. Assemble all machinery, like generators, pumps, etc., and test their operation. If they are
not operating properly, write to the supplier.
12. Put all the items into the store and hand them over to the storekeeper. The items need to
be recorded on the stock cards.
13. If there is any difference between the order and the items received, notify the supplier in
written form immediately.
14. After receiving the bill, compare it with the pro forma invoice. Check to see that transport
costs are reasonable. Send a copy of the bill with a request for payment to the Finance
Department for settling.
15. Enter payment into the finance book of the project. If in foreign currency, calculate in £S at
the official exchange rate.
16. Divide the transport and packing costs accordingly on each item and transform the
amount into £S. Conside all transport costs as well as any handling costs that may have been
charged.
Example:
No.
Quant
Unit
Item
Unit
Price
Supplier
US $
700
160
1
2
2
4
pcs
pcs
3
10
pcs
spare membrane
PURCHASE COSTS
Packing
Air Transport EUR - NBI
Road Transport NBI-Juba
Handling
by
Transport
Company/Loading/Unload.
TOTAL COSTS
diaphragm pump
hose, 10 m, ∅ 2
1
“
2
40
Total of
Supplier
US $
Unit Price
Juba US
$
Unit
Price
Juba £S
1,400
640
1,330
304
4,655
1,064
400
2,440
350
1,250
400
200
76
266
4,640
The “TOTAL COSTS” are the “PURCHASE COSTS” plus all other costs for transport,
handling, etc.
The TRANSPORT FACTOR is used to include all additional costs, thereby finding out the real
cost of each item.
TRANSPORT FACTOR =
TOTAL COSTS
4,640
=
= 1.9;
PURCHASE COSTS 2,440
17. Multiply each “UNIT PRICE SUPPLIER” by the TRANSPORT FACTOR.
The result is the “UNIT PRCIE JUBA, US $”, which includes packing, transport, handling, etc.
166
Inquire about the official exchange rate between US $ and £S and transform the “UNIT
PRICE JUBA, US $” into the “UNIT PRICE JUBA, £S”.
Example:
If US $ 1.00 = £S 3.500, then multiply all unit prices in US $ by 3.5. The result is the unit price
in £S.
Note that the price including transport, etc., is considerably different from the purchase price.
Knowing the real price is important for future budgeting and eventual sales.
18. Record the real prices (the “UNIT PRICE JUBA, £S”) on the stock cards.
19. Write a letter to the supplier, acknowledging receipt of the order and thanking him or her.
7.9 Storekeeping - Recording
Correct records are essential for storekeeping. They are done on stock cards, which are to be
filled in as follows (example see 7.9/3)
ITEM
Write a separate stock card for each kind and size of item. Therefore,
separate cards for ‘nails 2”‘, ”nails 3”‘, etc. Write under “ITEM” the exact
specification. Start with the general name, followed by the material,
followed by the size. For example:
not metal pipe
pipe, metal, ∅ 2”
bits for wood
not wood bits
Put spare parts under the main item. For example:
hacksaw blades
not blades, hacksaw
diaphragm pump, spares
not spares for diaphragm pump
Use always the same and only one name for one kind of item. For
example:
measuring tape, 2 m
not tape measure 2 m
measuring tape, 5 m
not tape measure 5 m
measuring tape, 10 m
not measuring tape 10 m
measuring tape, 50 m
not meter 50 m
Complete tool boxes are one item like handpump box, building box, welldigging box, etc. Write the name of the box under “ITEM” with the remark
“Contents on a separate list”. This list is to be kept with the stock card. A
copy of the list of contents remains in the box itself for on-site checks.
167
ALPHABETICAL
ORDER
UNIT
UNIT PRICE
ON
NUMBER
RECEIVED
NUMBER
ISSUED
BALANCE
TO/FROM
DATE
REMARKS
SIGNATURE
The stock cards are stored in a box in alphabetical order. They are
sorted according to the first word under “ITEM”, then the second, and so
on. Identical items differentiated only by size are sorted according to the
size with the smallest first.
Therefore, the following cards will be in this order:
4 gallons
jerrycan, metal,
1 gallon
jerrycan, plastic,
jerrycan, plastic,
4 gallons
or:
timber, hardwood,
2 x 2”, 3 m
timber, hardwood,
2 x 4”, 3 m
3 x 4”, 3 m
timber, hardwood,
timber, softwood,
2 x 2”, 3 m
timber, softwood,
2 x 2”, 6 m
The stocktaking list of the previous year is attached to the box of the
stock cards and can help you find the relevant cards.
Indicate in which unit the item will be counted. For example:
kg
nails
pcs
hammer, welded mesh, timber, pipes
m
rope, reinforcement
bag
cement, whitewash
set
drill bits, spanners of different sizes
lit
oil
gal
engine oil, fuel, paint
rolls
binding wire
The figures in the stock card below are always counted in the units
mentioned above.
Record the unit price in £S. If the same item is purchased later at a
higher price, cancel the old price and replace it with the new one.
Record the date when the price was valid.
Record the quantity received here. Fill a new line each time you receive
or issue an item.
Record the quantity issued here. When tools are put into any of the tool
boxes, they count as “issued”.
Add the number received to the balance of the line above and fill in the
result on the same line under “BALANCE”. Subtract the number issued
from the balance of the line above and fill in the result on the same line
under “BALANCE”. The “BALANCE” must equal the actual quantity in the
store.
Record to whom the item was issued (e.g. well No.4, latrine No.5, office,
handpump box, name of person).
Record from whom you received the item (e.g. market Juba, Khartoum,
Nairobi, building department).
Record the date of receiving or issuing.
Note any irregularity like “items spoilt”, etc.
The storekeeper needs to sign here. Thus it is clear, who is responsible
for issuing or receiving this particular item.
It is important to record all movements immediately. If that is not possible, due to lack of time,
never allow any item to leave the store without a notice on a piece of paper, which is to be
recorded later as soon as possible.
168
Sudan Council of Churches * Munuki Water and Sanitation Project
STOCK CARD
ITEM____ UNIT____ UNIT PRICE £S____ ON____
Number Received
Number Issued
Balance
To/From
Date
Remarks
Signature
Sudan Council of Churches * Munuki Water and Sanitation Project
STOCK CARD
ITEM CEMENT UNIT bag UNIT PRICE £S 115.000 ON 1.7.87
Number
Received
600
Number
Issued
Balance
To/From
Date
600
Nbi
1.7.
25
575
CL No.17
3.7.
Remarks
12 broken
7
568
CL No.21
7.7.
10
558
WS
9.7.
for rings in workshop
5
553
11.7
spoilt by rain
15.7.
returned loan of 1.3.87
50
603
-SCCBuild
Signature
7.10 Organising a Store
A well-kept store contributes to correct storing and the easy finding of items. It keeps us
aware of the amount of material in stock and helps to prevent losses. A good store is the
foundation of any project work and a mirror of the quality of work.
A) Principles of Storekeeping
Good storekeeping is based on the following principles:
1. The systematic structure according to which the items are stored must be easily
understandable for anyone at first glance. Thus, anyone using the store is much more likely to
place the items in the correct location without messing up.
2. Every item should be easily accessible without moving other items or climbing over them.
Thus, people are less likely to place items anyhow, maybe just in front of the door, or to move
items without putting them back in their right places. This also saves time and efforts.
169
3. The store should be clean, dry and orderly. It is much more likely that people mess up a
dirty place than a clean one.
4. Spoiling of items must be prevented and spoilt items need to be removed in order not to
occupy needed space.
B) Rules of Storekeeping
For implementing these principles, observe the following basic rules:
1. Store identical items at the same place.
For example, do not store timber of the same size in different places.
2. Store related items near to each other.
For example, store timber of different sizes or nails of different sizes near to each other. Store
different kinds of tools near to each other, and separate them from building materials, etc.
3. Always store the same items in the same place.
Write the name and/or draw a picture of the item on the shelf, wall, etc. Write the contents on
boxes or packed material. Do that even if it seems obvious, since you might forget later.
Especially, write difficult names on the shelves (like D-shackle, with drawing).
5. Always store lengthy boxes or other items with the short side facing the outside of the shelf.
Thus you can see the side of many boxes instead of few. Store the boxes with the label of
their contents facing the outside.
6. Store boxes, timber, etc., of the same kind above each other instead of beside each other
with other items on top.
Thus, each size/type is easily accessible without moving others.
7. Store items so that they are easily countable. For example, store cement, etc., in piles of 5
or ten above each other and 5 or ten piles beside each other. Always remove from one pile
until it is finished, then from the next.
170
easy to count: 104 bags
difficult to count: 24 bags
easy to count: 24 bags
Store nails in 1-kg boxes. Thus it is easier to determine how many are left, as compared with,
say, a single container containing 20 kg of nails.
8. Store as few items as possible on the floor. Provide sufficient shelf space. Hang whatever
possible on the wall or on the shelves. More can be stored on shelves than spread on the
ground.
That way, moving about in the store and cleaning will be made easier.
9. Put small items like nails, bolts, pins, etc., into labelled boxes.
10. Store rope and wire on a roll or hanging in rolls on a lever arm, or store rope in a box.
Thus any length can be easily cut off.
171
11. Store items in a stable way. Always store heavy items on the lower shelves. Turned-over
shelves or collapsed piles are a nuisance and are dangerous.
12. Take care that the store is airy, has ventilation openings and is dry. Immediately repair
any leaks in the roof or from below.
13. Store cut timber on a straight ground on at least three logs, never directly on the ground.
Optimal way of storing timber: each log is surrounded by air.
Possible way of storing timber: the air cannot reach all pieces.
Wrong way of storing timber: it gets wet, dirty and twisted, and ants can attack it easily.
14. Never store cement and fuel together. They will spoil each other.
15. Inflammable materials must be stored separately from other combu stible materials in an
area especially protected from fire.
16. Materials, such as cement, which deteriorate with the passage of time, must be kept
constantly moving by using the earliest arrivals first.
17. Clean the store regularly. Clean all returned items before putting them back into their
place.
18. Keep the store carefully locked, even if you leave it only for a short time.
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C) Equipment of a Store
- shelves,
- boxes,
- table,
- chair,
- stock cards in a box,
- file “LOANS”,
- file “SALES”,
- forms “WORK PLAN”,
- forms “WORK RECORDS LATRINE”,
- forms “WORK RECORDS WELL”,
- forms “TOOLS ON SITE”,
- forms “COST ESTIMATION/CALCULATION”,
- calculator,
- ruler,
- pens,
- pencils,
- marker pens,
- punch,
- stapler,
- string,
- glue,
- cellotape,
- lined paper,
- plain paper,
- carbon paper,
- jar 1 litre,
- jar 1 gallon,
- stocktaking list,
- balance scales,
- one copy of these chapters about storekeeping.
D) Example of Store Layout Plan
173
Scale 1:200
7.11 Storekeeping - Procedures
The task of the storekeeper is to implement the basic storekeeping procedures.
A) Issuing Tools for a Site (see 7.11/4)
174
Record tools to be issued to a site: first on the stock card, secondly on the form, “TOOLS ON
SITE”, which is to be filled out in two copies. Give one copy to the foreman/technician
responsible for the site; she/he has to account for any losses while on site. Let her/him sign
for the tools issued. The other copy remains in the store for the storekeeper to check the tools
as they are returned. Record complete boxes with their names (i.e., hand pump box, building
box, etc.), without listing each tool.
B) Issuing Materials for a Site (see 7.11/5; also 7.3/1f; 7.4/1,7ff)
Record materials to be issued to a site: first on the stock card, secondly on the form, “COST
ESTIMATION/CALCULATION”, which is to be filled out in two copies. Give one copy to the
foreman/technician responsible for the site. The other copy remains in the store. This is
needed for the final cost calculation.
Record materials for standard compost latrine construction, which are always the same
amount, only on the stock card.
C) Receiving Items
Check tools coming back from a site according to the form, “TOOLS ON SITE”, and enter the
receipt into the stock card. Check to see if the tools are in good condition.
Check items from the market according to the purchase list and enter them into the stock
card, including the prices.
Check items arriving from outside according to the waybill. Note missing or damaged items on
the waybill and sign all copies of the waybill. Enter the items into the stock card. Request the
prices from the office and enter them into the stock card as well.
D) Sale of Items
Issue items on sale, like latrine slabs, ventpipes, children’s squatting slabs, etc., only when
the buyer brings a receipt from the accounts office with a note from the senior staff. Record
the item in the stock card and fill in under “REMARKS”: “paid, receipt No...., date of receipt”.
Write on the receipt “Issued” with the date and your signature and give the receipt back to the
buyer. File the note into the paper file “SALES”.
E) Loans of Items
Items (equipment or tools) can be loaned only in exceptional cases. Issue the item only upon
a written approval from senior staff and file the approval in the paper file, “LOANS”. Enter the
loan into the stock card.
Write a list of all outstanding loans at the end of each year and present it to the office for
follow-up.
F) Purchase List
Note down any items which have been depleted, soon will be depleted, or are missing, on a
purchase list. Present these suggestions for re-purchasing to the concerned staff at the time
of purchasing.
G) Cost Calculations
When the work on a well or latrine is finished, the foreman or technician on site completes the
records of materials on the form “COST ESTIMATION/CALCULATION”, including the
materials contributed by the community. She/he hands the list to the storekeeper. The
storekeeper adds the prices according to the stock cards and hands the list to the office (for a
detailed description, see under 7.3 and 7.4).
175
H) Prevention of Loss and Misuse
A project store is a great asset but can create danger of loss and misuse. Additionally, the
question of misuse can cause founded or unfounded accusations, mistrust, and disturbance
in staff cooperation. The following suggestions may help to minimize such disturbances and
to prevent or reduce losses and misuse.
1. Suggestions for Senior Staff
- Normally, store keys should be handled by only one person. However, this might cause a
lot of inconveniences in the daily running of a project (especially for a small project with no
specially assigned storekeeper). The assignment of two people holding store keys is only
possible, if there is trust between them and if they keep strictly to recording each item
issued and received immediately. Otherwise, insist that only one person be responsible for
the store keys.
- In the case of very valuable items stored, provide the store with two padlocks and let two
different people hold the keys. Thus the store can be only used during the presence of
both.
- Assign one person to be responsible for tools on site or for a specific store, etc., and let
her/him sign when taking over. This strengthens the feeling of responsibility among staff.
- If staff members want to take items home (e.g. tools for use, scraps), insist that they keep
to the procedures, i.e. ask permission which should be granted whenever reasonable and
possible. If not, explain why. The staff should feel that they are treated reasonably and
justly.
- Pay a reasonable salary to storekeeper and technicians. Project properties are a great
and unfair temptation to underpaid staff with hungry children at home.
- In case of losses, make an inquiry. Do not blame anyone unless guilt is clearly proved. In
that case, take whatever steps are necessary. Otherwise, improve your supervision and
spend more time on regular checks. In case of proof misuse, dismissal is the only possible
action.
2. Suggestions for the Storekeeper
- Keep to the storekeeping procedures, especially, insist on authorizing documents when
issuing items.
- Keep the store in order. This helps to keep an overview.
- Label the shelves. Draw pictures of each tool on the wall on the place where you hang it.
Thus you realize immediately when it is missing.
- Store items like nails in packed quantities.
- Store items in an easily countable way. Thus you can check the number easily any time.
- Keep your records in order and up-to-date.
- In case of any suspicion against you, insist on the presence of a second person when
handling the store.
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Sudan Council of Churches * Munuki Water and Sanitation Project
TOOLS ON SITE
Well/Latrine No ................ Community/Owner: ......................... Site: ..........................
Quantity
Unit
Item
Date
Issued
Signature
Storekeeper
Signature
Foreman
Date
Returned
Remarks
Sudan Council of Churches * Munuki Water and Sanitation Project
COST ESTIMATION/CALCULATION FOR ................................................
No.
Quantity
Unit
Item
Unit Price
Total
Contributed by
7.12 Stock-Taking
The annual stock-taking is essential in order to determine the assets of the project and to
check if anything is lost. The stock-taking report is part of the annual report of the project. The
stock-taking is done at the end of the year and is connected with general cleaning of the store
and maintenance of equipment.
Stock-taking and cleaning of a big store takes time. Plan on taking several days with sufficient
staff. Follow these steps:
1. Collect all tools and equipment from outside sites.
2. Clean the whole store and put it in good order.
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3. Go through all the stock cards. Count the quantity of all items available in the store and
compare it with the last balance in the stock card. Tick it if they correspond. If items are
missing, consider whether they may be on outside sites or on loan to somebody. If anything
else is missing and somebody is responsible for the loss, she or he should be made to pay for
it. Record unaccountable losses or losses due to normal spoiling as follows:
Put the quantity missing under “ISSUED” and write “lost” or “spoilt” under “REMARKS”.
4. Write the stock-taking list. Preferably this should be done in a quiet place with a desk.
The stocktaking list looks like this:
Stock-taking List
Year: ..............................................................................................
Project: ...........................................................................................
Store: ..............................................................................................
Quant
Unit
Item
Unit Price
Total
Total Depreciated
Fill in for each stock card one line.
Fill in under “QUANTITIY” the number of the last “BALANCE” on the stock card. Fill in “UNIT”,
“ITEM”, and “UNIT PRICE” according to the stock card.
Multiply “QUANTITY” with the “UNIT PRICE” and fill in the result under “TOTAL”.
Calculate the “TOTAL DEPRECIATED” for each item.
Do not depreciate material, equipment and tools, which have not been used, but just stored in
stock. For these items the “TOTAL” and “TOTAL DEPRECIATED” are equal.
Depreciate all equipment and tools which were used as shown in the following example:
Year
1.
2.
3.
4.
Depreciation
25% from original price
50% from original price
75% from original price
100% from original price
To get the “TOTAL DEPRECIATED” multiply the “TOTAL”
by the factor
x 0.75
x 0.50
x 0.25
The “TOTAL DEPRECIATED” = 0
The first year is the year following the purchase.
Example:
Pipe moulds purchased in 1985
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Year
1985
1986
1987
1988
1989
Quant
3
3
3
3
3
Unit
pcs
pcs
pcs
pcs
pcs
Item
pipe moulds
pipe moulds
pipe moulds
pipe moulds
pipe moulds
Unit Price
4,000
4,000
4,000
4,000
4,000
Total
12,000
12,000
12,000
12,000
12,000
Total Depreciated
12,000
9,000
6,000
3,000
Fully depreciated items are recorded in the stock-taking list (they are still around and may still
be used), but the “TOTAL DEPRECIATED” (= the depreciated value) is recorded as nil.
After filling in all items on the stock-taking list, add up all “TOTAL DEPRECIATED”. The result
will be the “GRAND TOTAL”.
The work of filling in the stock-taking list can be drastically reduced if a photocopy of last
year’s stock-taking list is used and the changes are filled in. Afterwards the new stock-taking
list can be typed.
5. Hand the stock-taking list to Administration. There, vehicles and office assets will be added.
The final stock-taking list is attached to the annual report (see 2.6/3).
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8. Water Supply
8.1 Story about Good Water Supply
Jam 3,11
The following chapters mainly tackle the technical aspects of water supply. However, the
technical aspects are only one element of a successful, good water supply. The social and
educational aspects are at least as important, but not the main topic of these chapters. A
story about good water supply is recorded her as an example which can be used in the
educational work with the community.
THE FOOLISHNESS OF MAN
God had created everything: the cattle, the goats, the dura, the fire, and the water. So one
day he called the creatures: lion, hyena, bird, hippo, and man. God told them to ask for one of
the things he had created. The lion choose the cattle. The hyena wanted the goats. The bird
asked for the dura. And the hippo took the fire. Then man was left with only water and he
complained: “I wanted the cattle!” But God told him to take the water, that it was a good gift.
So, the lion went away with his cattle and ate one of them. Then he rested. When he woke
up, he was very thirsty. When he came to the water, the man said: “Go away. The water
180
belongs to me.” “But I am very thirsty. I will give you a cow.” “That is not enough, “said the
man. So the lion gave man all the cattle, and man let the lion drink.
...and the same thing happened with the hyena, the bird, and the hippo...
And so man had everything: the cattle, the goats, the dura, the fire, and the water. But
sometimes the lion or the hyena or the bird or the hippo would sneak up and steal one of
these things from man because they had nothing.
One day God looked down at this man who had the water and the cattle and the goats and
the dura and the fire. And he saw that man drank water from the river and that he bathed in
the same place and that the cattle came into the water to drink. And other people used the
river as a place for urinating. And God was unhappy. He looked again at man. Man was
crying with indigestion, diarrhea with blood and bilharzia every day. So God called the fox.
“Go! Talk to the foolish man. I have given him all the water and he does not know how to keep
it safe. Man cannot drink the water where man and cattle bathe. Man cannot bathe in water
which is a place for urine and stool. Man will have to find the hidden water I have given him.”
So fox went to man. “Oh, foolish man! You have spoiled this big gift of water and now you
have many sicknesses. Do you want these sicknesses always?” “Oh, fox! How can these
things truly go away?” And fox told man to dig a hole for the hidden water and to put a cover
on the top to keep dirt and germs from getting in. Then the fox told man to buy a pump to
draw the water out so that no unclean bucket would touch the water.
And man did as fox suggested. And man had healthy water and the diseases stopped. And
man was happy again. And God looked down and shook his head and said: “What kind of
foolish man!”
8.2 Connection of Water Supply with the Community
Gen 26,12-21; Ex 17,1-7; Num 20,1-13; Dtn 6,11; Js 41,17-20; Jer 14,3 Ez 29,3; Jn 4,5-30
Water supply is not a private, but a community facility. Therefore, the whole community needs
to be involved in
1. Decision taking (about price, location, construction, caretaking),
2. Construction,
3. Correct handling,
4. Control of use,
5. Maintenance and repair.
The community is not in need of any water point, but of a water point,
1. considering social connections, to be used by any citizen irrespective of religion, tribe
and race,
2. at a suitable location,
3. under control of the proper people,
4. with water in sufficient quantity (the aquifer not being completely exhausted),
5. with water of good quality,
6. easy to operate, especially for children,
7. easy to maintain,
181
8. with the appropriate infrastructure (spare parts available, etc.).
See also 8.29/1f.
8.3 Process of Community Development - Water Supply Cooperation
Water supply measures without community involvement are a common practice in many
places, however, community involvement has invaluable advantages, although difficult,
tiresome and slow. Therefore, community involvement should always be pursued.
A community development process with several meetings needs to take place before and
during the start of the technical work.
Ideally, the community contributes whatever it is able to contribute depending on the situation,
such as:
- unskilled labour,
- local materials,
- feeding of project staff on site,
- cash,
- participation in the operating instruction,
- selection of caretakers for operation and maintenance.
The project contributes whatever the community is not able to provide, such as:
- know-how,
- skilled labour,
- equipment,
- materials from outside,
- transportation,
- supervision,
- operating instruction,
- training for the caretakers.
The form on 2.5/6f is an example of an agreement between a project and a community about
the construction of a well.
See also 8.29/1f.
8.4 Cooperation of Water Supply Technicians with the Community
Dtn 6,11b
For successful cooperation between the technical staff and the community, the technicians
have to act in certain ways and keep to certain working principles.
The following attitudes need to be observed:
1. Community cooperation is voluntary. If the community wants to achieve its aim, i.e. a
well, they need to bring their contribution. If not, no well is going to be built. It is up to them.
The project staff should not try to persuade the community or to put pressure on them.
2. The project staff needs to act with great respect towards the members of the community
and their capabilities.
3. The project staff needs to be clear and consistent in its relationship with the community.
182
The following working principles need to be kept:
1. Inform the community ahead of time about your coming.
2. Keep tools, equipment, files, behind when you arrive until people are ready to accept
them. At first, they might be frightening.
3. Always greet everybody upon your arrival.
4. Behave in a polite manner, quietly and patiently, with respect.
5. Assemble all people of the community and project before starting work on a new site.
This is the time for greetings, explaining the work, discussing questions, and prayer.
6. Talk in an understandable language. Avoid difficult, especially technical expressions.
Make sure that everything is translated.
7. Consider women equally.
8. Avoid embarassing illiterates by handing them written documents. If necessary, ask for
somebody from the community who knows to read (normally the secretary of the well
committee).
9. Accept anything offered to you with kindness (chairs, drink, food). You may ask, but do
not request.
10. If you bring your own clean drinking water, do not boast with its cleanliness and do not
belittle the water of the village. Share your water, if asked.
11. Do not implement any water supply work if the community did not meet its contribution.
12. For necessary communication approach the members of the committee rather than
individuals.
13. Give priority to solve relationship problems and social conflicts during the process of
work.
14. Do not let yourself get involved in inner organisational problems of the community.
15. Call for a community meeting in case of any community related problems instead of
trying to solve them on your own.
8.5 Importance of Adequate Water Supply
Human beings need water
directly for (in order of their priorities)
1. Drinking,
2. Cooking,
3. Taking bath,
4. Washing kitchen utensils and cleaning,
5. Washing laundry;
indirectly for
6. Cultivating their food (rainwater or irrigation),
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7. Watering their animals and thus producing food,
8. Fishing,
9. Building,
10. Generating electrical power,
11. Exstinguishing fire,
12. Running machines,
13. Recreation,
14. Cooling,
15. Flushing latrines,
16. Industries and others.
Water is needed (in order of their priority)
1. in sufficent quantity,
2. in good quality.
Inadequate quantity of water affects the health of people by
1. not enough water to drink
2. not enough water to cook, therefore not enough
food
3. not enough water for cleaning kitchen utensils
4. not enough water for taking bath
5. not enough water for the laundry
6. not enough water for cultivation
7. not enough water for animals
→ dehydration,
→ malnutrition,
→ transmission of diseases,
→ development of skin and eye
diseases,
→ skin diseases,
→ malnutrition,
→ malnutrition.
Bad quality of water affects the health of people by
- transmitting water related diseases.
See also 8.29/1f.
8.6 Water Related Diseases
Most diseases in Sudan are due to one of the following reasons:
1. Lack of sufficient water,
2. Lack of clean water,
3. Lack of sufficient sanitation,
4. Lack of preventive health care (immunizations etc.),
5. Lack of curative health care (personnel, facilities, etc.),
6. Relying on (traditional) medicine without consulting medical personnel,
7. Unbalanced diet,
8. Poverty,
9. Distribution of land,
10. Difficult life conditions in parts of the country,
11. Great number of household members,
12. Certain values and beliefs.
A great number of the diseases are related to inadequate water supply. They can be
differentiated according to five groups:
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Name
water borne diseases
Description
carried
by
water,
infecting consumers
parasitic diseases
organisms causing the
disease spend part of
their life cycle in an
aquatic host
caused by insufficient
water for washing and
hygiene
filth born diseases
diseases of dirt
=
water associated diseases
spread by insects
breeding in water
diseases by polluted water
caused by
chemically
water
drinking
polluted
Diseases
cholera
dysentery
typhoid
hepatitis
amoeba
giardia
diarrhea
polio
guinea worm
bilharzia
filariasis
Help
provide
clean (safe)
water
scabies
tropical ulcer
trachoma
eye infections
malaria
river blindness
sleeping sickness
yellow fever
cancer
kidney trouble
mottling teeth
skeletal fluorisis
provide sufficient
quantities of water
provide
clean (safe)
water
remove
pools,
flooded la- trines
and other breeding
places
prevent chemical
pollution of water
WATER RELATED DISEASES
Sickness
Other Names
Cause
Vector
Cholera
toxin,
released
gut
bacteria
people,
in flies
by
(bacterial) shigella,
Dysentry shigellosis
bacteria
(several
different
ones)
people,
flies
Typhoid
bacteria
people,
flies
enteric fever
185
Transmission
Preventive Measures
before
during
sickness
sickness
contaminated good
isolation,
water
and hygiene,
good
food, incl. ice latrines, safe hygiene,
and
cold water
safe water,
drinks,
disinfect or
burn
the
uncovered
clothes and
faeces
blankets,
boil plates
and cups,
disinfection
of stools
contaminated good
isolation,
water or food hygiene, safe separate
water, clean plates and
and
well cups
prepared
food, latrines
contaminated good
isolation,
water
and hygiene, safe disinfection
food, faeces water,
of
stools,
to mouth
latrines
wash hands
after latrine
Sickness
Other Names
Hepatitis
A
Hepatitis
B
Cause
virus
Polio
poliomyelitis
virus
Amoeba
amoebiasis,
amoebic
dysentry
parasite
Giardia
giardiasis
parasite
Diarrhea
gastroenteritis
bacteria
Guinea
worm
dracunculiasis
parasite
Bilharzia
schistosomiasis parasite
- Mansoni
- Haematobium
Scabies
7-year itch
Tropical
Ulcer
parasite
bacteria
Vector
Preventive Measures
before
during
sickness
sickness
A: faeces to good
people,
isolation,
mouth
B: hygiene, safe separate
flies,
monkeys blood - using water,
plates and
needles
of latrines,
cups,
other people sterilized
extremely
medical
good
equipment hygiene
people,
contaminated good
isolation,
flies
food
or hygiene, safe good
water, close water,
hygiene,
contact
vaccination, safe water
latrines
people,
contaminated good
wash
flies
food
or hygiene, safe hands after
water, poor water,
desanitation
latrines, keep faecation
flies off food and before
meals
people,
see
under see
under see under
flies
dysentry
dysentry
dysentry,
papaya
seeds
protect
people,
see
under see
under see under
flies
dysentry
dysentry
dysentry
safe
water cleanliness,
cyclops in infected
supply,
roll
worn
standing
person
water (well stands
in drainage of slowly on
small stick
or pond)
water
or standing
(may take a
muddy place, water
week,
do
warm
lays
not break
larvae
into
the worm),
the
water,
do not go
people drink
into water
contaminated
water
snail
urinate and
swimming or avoid
(releases walking
in swimming, defaecate
parasite
only
in
infected
walking,
into water) water
bathing
in latrines
(parasite
infected
penetrates water,
e.g.
the skin)
the
Nile,
control
snails,
latrines
scabies
close
skin avoid contact wash
all
mite
contact with with infected clothes and
infected
person, good furniture
person
hygiene
with
hot
water and
soap
filth, friction, good
daily
trauma
hygiene, safe cleaning of
the ulcer
water
186
Transmission
Sickness
Other Names
Cause
Vector
Preventive Measures
before
during
sickness
sickness
Trachoma chronic
bacteria
people,
by flies or good
wash
left
conjunctivitis
flies
touch
by hygiene, safe and
right
contaminated water, early eye
fingers
treatment
separately
Eye
conjunctivitis
bacteria
people,
see
see
see
infections
flies
trachoma
trachoma
trachoma
Malaria
parasite
mosquitoes mosquito
mosquito net, early
(plasmodium)
bites
screening,
treatment
shut
doors to prevent
and windows anaemia
in
the
evening, cut
grass short
fill in pools
River
onchoceriasis parasite
black fly
fly bites
control
of control of
blindness
black fly
black fly
Sleeping trypanosomiasis parasite
tse-tse fly fly bites
protecting
sickness
clothes, clear
bush
Yellow
jungle fever
virus
mosquitoes mosquitoes vaccinations, isolation,
fever
living
in drain
mosquito
areas
with breeding
net
monkeys
places
Filariasis Wuckeria worms
- people to mosquito and clearing bush mosquito
Bancrofti
mosquito fly bites
and
grass, net, insect
- Loa Loa
- people to
drain water repellants
fly
Cancer
chemicals in
drinking
drink
early
water,
and
polluted
chemically treatment
others
water
clean water
Kidney
kidney stones water
with
drinking
drink water drink plenty
troubles
too
much
polluted
with low salt of water
salts
water
content
Mottling of
fluorides in
drinking
defluoridation early
teeth
drinking
polluted
of
water treatment
Skeletal
water
water
supply
fluorosis
compiled by Inga Andersson
187
Transmission
8.7 Basic Facts about Water
Ez 34, 18-19
A) Distribution of Water
No.
1
2
3
4
5
6
Location
Name
Water in vegetation, animals,
human beings
Water in the air (clouds, rain)
Water in lakes, ponds, rivers,
swamps
Water in the soil underground
Ice caps, glaciers, snow
(salty) water in seas and oceans
water
in
biosphere
water vapour
surface water
groundwater
frozen water
seawater
in
oceans
TOTAL
Volume
(approx.)
1,000 km3
Percentage
14,000 km3
135,000 km3
0.001 %
0.01 %
8,400,000 km3
29,350,000 km3
1,362,100,000
km3
1,400,000,000
km3
0.6 %
2.1 %
97.3 %
0.00007 %
100.00 %
Water in the air, in the biosphere, frozen water and seawater are not readily available for
water supply. Therefore, water supply for humans mainly relies on groundwater and surface
water. Surface water is not available in all locations, whereas groundwater is available in
many locations and is the main source of water supply.
Distribution of Groundwater
75 % less than 50 m deep
25 % deeper than 50 m
Hand dug wells are ususally constructed up to 50 m depth (depending on the conditions).
That means that the majority of groundwater is within the scope of hand dug wells.
See also 8.11.
B) Properties of Water
Some properties of water are listed in the following:
- It consists of hydrogen and oxygen; the chemical formula is H2O.
- It is transparent.
- It is colourless (with a blue tinge in large bodies).
- It has no taste.
- It exists in three physical stages:
* solid = ice
* liquid = water
* gas = vapour
- The ratio between the weight of water and the weight of (dry) air is 830:1; therefore,
water falls in air.
- The ratio between the weight of vapour and the weight of (dry) air is 1:133; therefore,
vapour moves upwards in air.
188
- The freezing point of water is 0°C.
- The maximum density of water is at 4°C.
- The boiling point of water is at 100°C (changing with atmosphere pressure).
- The ratio between the weight of ice and the weight of water is 1:11; therefore, ice floats
on water.
- Water is practically incompressible.
- It has capillarity, that is the ability to move upwards in small diameter openings because
of cohesion (= the ability to stick together) and adhesion (= the ability to stick to a surface).
- It is an universal solvent; therefore, natural water contains gases and mineral salts in
solution.
C) Movement of Water
1. Hydrological Cycle
2. Transportation of Water from the Sea into the Continent
Water
- evaporates over the sea,
- travels by cloud several 100 miles,
- rains on forest,
- evaporates from forest,
- builds new clouds,
- travels to next forest several 100 miles away.
That means that water travels in “jumps”. Therefore, forests are essential for the
transportation of water into the continent.
189
D) Dangers for Water
Our groundwater is a most valuable resource essential for life. It is in danger in many ways:
1. Water Is in Danger of Bacteriological Pollution
Flooded latrines, latrines too close to wells, leaking septic tanks, overflow seepage wells of
septic tanks, and defaecation in the open pollute the water with disease transmitting bacteria
and viruses. Bacteriological pollution can be cleaned through filtering and disappears by itself
with time passing (see also 9.8).
Therefore:
- Do not construct latrines which will be flooded!
- Do not construct latrines near to wells!
2. Water Is in Danger of Chemical Pollution
Flooded latrines increase the nitrate and nitrite concentration in the water (nitrate and nitrite
are produced in the decomposition process and are then dissolved in the water).
Poisons like DDT, artificial fertilizers and pesticides, spilled engine oil, diesel or petrol, acids,
etc. pollute the water chemically. It is very difficult, mostly impossible, to remove chemical
pollution from water (see also 3.11/2; 9.13/2f; 9.16/2; 9.22).
Therefore:
- Avoid the use of poisons like DDT, pesticides, etc.!
- Be careful not to spill engine oil, diesel, petrol, etc.!
- Never pour old engine oil on the ground!
3. Water Is in Danger by Removing Vegetation
Rainwater falling on barren soil will run off quickly and will have no time to infiltrate into the
ground and, therefore, to add to the ground-water. (Beside that, winds will carry away the top
soil which is fertile.) Soil with vegetation retains the rainwater and allows it to infiltrate into the
soil(see also 8.9).
Therefore:
- Do not burn the grass on the fields! If burning is absolutely necessary, do it just immediately
before planting the new crops and make sure that the area is limited.
- Do not overcultivate and do not allow overgrazing!
4. Water Is Endangered by Cutting Trees
190
Trees transport water from the groundwater through their roots up to the leaves. They form
clouds through their evaporation. Therefore, forests are essential for creating rain.
People cut trees for clearing fields (and building houses without planting young trees. Tree
seeds and young trees are killed by agricultural fires. People contribute to the reduction of
rains by neglecting the trees.
Therefore:
- Plant young trees and protect them!
- Cut only as many trees as absolutely necessary! For each tree cut, plant three young ones!
- Do not burn grass!
8.8 Groundwater
191
A) Water Storage
The ground soil normally contains air in its pores and is able to store water instead of air in
the pores. The water content can be differentiated as follows (see also 8.8/4):
The Soil Is
The Soil Contains
dry
wet
air, but no water
air and water
saturated
water, but no air
Name
soil layer without water
capillary zone or unsaturated
zone
aquifer or saturated zone
Suitable for Well
Intake
no
no
suitable
B) Properties of Ground Soil
The soil has the following properties regarding water:
- It stores huge amounts of water.
- It prevents evaporation of the water.
- It preserves the quality of water.
- It cleans the water from bacteriological pollution.
- It enriches the water with minerals, etc.
- It makes the water available for trees, wells, springs, etc.
- It balances changes in the climate (dry season - rainy season, droughts).
- It allows vertical transportation (= infiltration).
- It allows horizontal transportation (“underground streams”, horizontal seepage).
- It releases water to wells, springs, etc.
- It preserves the water temperature.
- It can make water dirty if the soil is polluted by poisons, old engine oil, fuels, etc.
C) Properties of Aquifers
Two main properties are essential for aquifers (= water bearing layers):
1. porosity
2. permeability
Soil
clay
sand
gravel
sandstone
= measure for the ability to store water
= property of permitting the through-flow of water
Porosity
54 to 557.
35 to 407.
30 to 407.
10 to 207.
Permeability m3/day × m2
0.00005 to 0.1
5 to 150
50 to 750
0.005 to 2.5
D) Types of Aquifers
Often there are different soil layers above each other. They can constitute the following types
of aquifers:
1. (Open) Aquifer (= unconfined aquifer = open groundwater)
An aquifer is a saturated porous soil layer containing and transporting water. There can be
several aquifers above each other, divided by impermeable layers.
An impermeable layer contains no or little water and does not allow water to infiltrate through
it. However, impermeable layers are seldom continuous, therefore, water can pass through
the incontinuities.
192
2. Artesian Aquifer (= confined aquifer)
An artesian aquifer is confined by an impermeable layer. If tapped by a well, the water table
raises in the well up to the “piezometric surface”. See also 8.35/3.
3. Trapped (or Perched) Aquifer
A trapped aquifer is a limited aquifer surrounded by impermeable layers. The recharge is
limited; therefore, a well tapping a trapped aquifer can be exhausted and dry out (see also
8.29/1).
E) Movement of Groundwater
Groundwater can move in two different directions (or mixtures of the two):
193
1. Vertical Movement
Rainwater infiltrates vertically into the ground by gravity. Also, strong pumping in a well can
force the water to move vertically downwards through different layers. Vertical movement is
the main movement of groundwater.
The infiltration of water into the ground is influenced by the following factors:
- Steep slopes cause quick run-off, and there is little infiltration into the groundwater.
- Gentle slopes hold the water longer and favour infiltration. They often offer more
favourable conditions than completely flat areas.
- Flat areas often develop a tight surface which hinders infiltration.
- Moderate rainfall over an extended period favours infiltration.
- Heavy rains saturate the surface quickly and most water is running off. They compact the
soil and reduce its ability to absorb water.
In a vertical cross-section, the ground can be divided into different zones according to their
water content:
2. Horizontal Movement
The groundwater moves horizontally into a well. Water also can travel horizontally through an
aquifer, especially, if the aquifer is sloping. However, this movement is very slow and very
limited in distance.
Therefore:
Do not draw more water from a well than is recharged by rain nearby! See also 8.29/1.
194
F) Connection between Rivers and Groundwater
A river and the groundwater can be connected in different ways:
Influent Stream: looses water to the aquifer
Effluent Stream: gains water from the aquifer (the sane stream may have influent and effluent
sections)
Stream only Flowing Periodically: dry during drought
195
Stream Isolated Hydraulically: from an artesian aquifer below it
G) Types of Soils as Aquifers
Type of
Soil
Porosity
Permeability
clay
good,
can
store lot
of water
sand
good,
can
store lot
of water
very
good
can
store lot
of water
good
limited
or
impermeable,
however, no
continuous
layers
very good
gravel
weathered
rock
rock
(=
basement
complex)
mixtures
of
soil
types
no
except
in
cracks
Difference
betw.
Unsaturated
and
Saturated
Zone
several
meters
Cleaning
Capability
Rechargeability
good
fair
fairly
good
slow
intake,
limited
recharge
no
very good
very good
very
good
quicksand,
collapsing
very good
no
no
good
very
good
collapsing,
easily
polluted
good
no
bad
very limited
good if
nothing
else
available
no, except in
cracks acting
as pipe
no
no
very limited
good if
nothing
else
available
only
limited
layers,
therefore,
limited
amount of
water
difficult to
hit
the
cracks,
difficult to
dig, limited
storage
water can
be
salty
because
of
dissolved
minerals
properties differ from site to site
196
Quality
of
Aquifer
Possible
Problems
8.9 Desertification
Is 41,17-20; Jer 6,8; Mi 7,13
Sudan is in danger of becoming a desert. The desert in the North approaches the South by 6
km every year. That means, if nothing changes, the desert may reach Juba in 100 years time,
that is just four generations.
The following contributes to desertification
- less rain,
- less forests through cutting of trees and burning of grass,
- less fertile soil because the soil is stripped off its vegetation and thus blown and washed
away,
- big agricultural schemes (through digging by tractor, cutting of trees, pesticides and
artificial fertilizers),
- Jonglei Canal,
- bombing, spraying of herbizides in war, atomic bomb,
- too many animals and, thereby, overgrazing,
- overpopulation and, thereby, overcultivation,
- exporting timber and charcoal,
- boreholes with water tanks in remote areas (attracting many people and animals).
What can people do to stop desertification?
- Stop burning grass!
- Plant and care for trees!
- Plant hedges around fields!
- Slow down the run-off of rainwater by small dams and ditches across the run-off direction in
your gardens!
- Minimize firewood, charcoal and paper consumption!
- Reduce the number of animals!
- Do crop rotation!
- Manure your fields!
197
8.10 Wells
A) Tapping Groundwater
A hole dug or drilled into a saturated soil layer and lined to prevent collapsing is called a well.
The static water table (= undisturbed water table) is the level of groundwater if no water is
pumped from the well.
The draw-down of a well is the difference between the undisturbed water table and the water
table in the well while pumping (= disturbed water table).
If more water is pumped from the well than enters from the surrounding groundsoil into it, the
water table will sink.
If less (or no) water is pumped than entering the well, the water table will rise (but, of course,
never above the static water table). If the same amount of water is pumped as enters the well,
the water table remains constant. This water table is called “dynamic water table”. The
amount pumped is equal to the yield of the well (which is the capacity of the groundsoil to fill
the well). The yield of a well can be measured by test pumping. The pump’s yield is gradually
increased. When the water table remains constant, the pump’s yield is equal to the well’s
yield.
Summarizing, we differentiate three different types of water tables:
No.
1
2
Name
static = undisturbed
table
disturbed water table
3
dynamic water table
water
Description
water table without pumping
water table while pumping at any rate, either sinking
or raising
water table while pumping with a specific rate equal
with the water entering the well; water table remains
constant
198
During pumping the water is drawn from an extended area around the well. By pumping we
do not only empty the volume inside the well, but also a space in the shape of a funnel around
the well (also called “cone of depression” or “draw-down line”). The volume pumped from
outside the well can be as big or even much bigger than the volume pumped from inside the
well, depending on the diameter and the draw-down. The greater the draw-down, the more
water needs to be pumped from outside, and the more difficult it is to lower the water table
further.
Big diameter well and small diameter well (borehole) with the sane draw-down:
The cone of depression differs in shape and size depending upon
1. pumping rate,
2. length of pumping period,
3. aquifer characteristics,
4. slope of water table,
5. recharge within the zone of influence of the well.
B) The Elements of a Well
Each well consists basically of the following elements:
199
Name
intake
= bottom section
Function
- allows water to enter from the
ground into the well excluding the
soil
- provides storage reservoir
- provides access to the well
bottom
- prevents pollution by surface
water
- prevents collapsing
- prevents or reduces pollution
- provides facilities for drawing
water
shaft
= middle section
well head
= upper section
well surroundings
- prevent pollution by animals
- control use
Construction
- lining with seepage holes, or
- porous lining (filter rings), or
- filter pipes for casing
- lining with concrete rings, or
- brick lining, or
- casing pipes
- preferably sealed (concrete
cover, apron, drainage)
- hand pump, engine pump, or
bucket system
- cleaned, fenced area
C) Influence of Diameter
The diameter of a well has the following influence on the function:
Influence on
water
construction
suitability
Increasing Diameter
- increase in yield
- more storage capacity
- more digging
- thicker lining necessary
- more materials needed
- more difficult to pump during
construction
- more space during construction for
2-3 people
- more danger of collapsing
- better ventilation
- in aquifer with low permeability
(slow intake)
- in not too deep wells
Reducing Diameter
- less yield
- less storage capacity
- less digging
- less lining
- less materials
easier
to
pump
during
construction
- narrow for digging (only one
person can dig)
- more stable
- danger of ventilation problems
- in aquifer with high permeability
(quick intake)
- in deep wells
It is important to choose the correct diameter suitable for the particular location. Huge
diameters (up to 10 m) are suitable for aquifers with very slow seeping in.
200
Big diameter wells (Ø 1.40 to 4.00 m) are suitable where the permeability of the soil is limited
and the water enters slowly into the well. In these cases a big filter surface and a big storage
capacity are necessary.
Medium diameter wells (Ø ca. 1.10 m) are suitable where the groundwater is deep.
Small diameter wells (boreholes) are suitable in rock, in case of very deep water tables. The
soil must be permeable, because the storage capacity of boreholes is very little.
For diameters of concrete rings, used for well construction, see also 8.16/4ff.
D) Increasing the Yield of a Well
The yield of a well can be attempted to be increased by one or several of the following
measures:
1. Increase the depth of the well.
2. Increase the diameter of the well.
3. Clean cracks in the intake area.
4. Clean away collapsed clay around the lining and replace it by gravel.
5. Increase the porosity of the intake lining (i.e. by additional holes).
6. Pump the well for few days as much as possible (This opens ways in the groundsoil).
However, the yield of a well can only be influenced to a certain degree. It depends on the
location chosen, the soil conditions, and the quality of the aquifer. Even a limited yield of a
well can be useful in a certain location, and the conditions given by nature need to be
accepted.
201
8.11 Comparison of Borehole and Hand Dug Well
Boreholes and hand dug wells can be differentiated according to the following features:
No
Feature
Drawing
Borehole
Hand Dug Well
1
Definition
2
Depth
3
Diameter
well excavated with equipment
from the surface
deep: 10 to 200 m
see 8.7/1
small: 5 to 20 cm
4
5
Form
Intake
6
Storage capacity
well dug by people enter-ring
the well
shallow: 3 to 50 m (in
exceptional cases up to 150 m)
big: 1 to 4 m (a person can
enter)
round or square
from the side through filter rings
and from the bottom
large because of big diameter
7
Well shaft
8
Well head
pump with platform
see 8.19/3f
9
Drawing of water
10
Digging
by handpump or
by engine pump or
by bailer
see 8.24
drilled by drilling rig, sometimes
by hand
round
only from the side through filter
casings
relatively small because of small
diameter
casing from steel or PVC pipe or
no lining in rock
202
lining from brick wall
or stone wall
or concrete rings
or no lining in rock
open with platform or closed
with concrete slab and pump;
see 8.19/5f
by rope and bucket or
by winch or
by handpump
or by engine pump; see 8.24
dug by hand
No
11
Feature
Labour needed
Borehole
high-skilled labourers in small
numbers
12
13
Time needed
Material needed
14
Equipment
needed
Energy needed
Space needed
relatively fast
casing pipes, cement, sand,
gravel, water, pump, etc.
highly sophisticated machinery
(= capital intensive)
fuel, engine oil
large area needed for rig
15
16
17
18
19
Accessability
required
Transport
needed
Risks involved
20
21
Costs
Availability
resources
22
23
Community
participation
Water quality
24
Yield
25
Maintenance
26
27
Rehabilitation
yield drops
Life time
28
Beneficiaries
for heavy lorry
lot of transport needed
of
common dangers of working
with
lorries
and
heavy
machinery
very expensive
most resources from abroad (rig,
fuel, casing, highly skilled
labour)
very limited
safe if surroundings clean,
platform intact, groundwater not
polluted
depending on conditions, often
limited, esp. in rock
maintenance of pump, daily
cleaning of surroundings
if
hardly possible
limited by corrosion of casing,
clogging of filter casing, breakdown of pump
well users, few local labourers,
foreign companies
Hand Dug Well
some
skilled
and
many
unskilled labourers needed (=
labour intensive)
time consuming
cement,
sand,
gravel,
reinforcement, pump, etc.
hand-tools like pick axe, shovel,
bucket, rope, etc.
human energy
large
area
needed
for
excavation
for pick-up, eventually only for
people footing
little transport needed
danger of working inside a well
moderately expensive
most resources from with in the
country
community
can
easily
participate in construction
safe if closed and surroundings
clean and groundwater not
polluted
depending on conditions, often
quite high
inside cleaning yearly, daily
cleaning
of
surroundings,
maintenance of pump, if
installed
cleaning and digging deeper
possible
limited by eventual dropping of
water table
well users, local labourers, local
manufacturers and suppliers
The above mentioned factors determine whether a borehole or a hand dug well is suitable for
a particular situation. Under certain conditions, a hand dug well is not suitable, but a borehole
can be drilled. Under certain conditions, a borehole is not suitable, but a hand dug well can be
constructed. Under certain conditions, both borehole and hand dug well are possible (see
8.7/1).
When both borehole and hand dug well are possible, governments, development agencies
and many people tend to favour boreholes. In many countries facilities and training are readily
available for boreholes, but neglected for hand dug wells. This is a bias towards foreign
resources and technology.
SCC’s water and sanitation project pursues a different policy: Wherever construction of hand
dug wells is possible, they should be favoured because of maximum utilization of local
resources and possible community involvement. The resources for boreholes shall be utilised
where hand dug wells are not possible.
203
8.12 Selection of Well Sites
Gen 26,32
The selection of a suitable well site is essential for the success of a well.
A) General Requirements
A suitable well site has to meet the following requirements:
1. It should be within walking distance (1-2 km) from the relevant village.
2. It should be accessible by pick-up/truck during the construction phase, and accessible
for the villagers throughout the year.
3. It should not be within 100 m of cattle pools, latrines or other health hazards (like septic
tanks, workshops, etc.), and preferably upstream of these. The distance depends on the
soil conditions. However, 100 m lies on the safe side. 50 m distance can be acceptable
under certain conditions. Closed compost latrines require a distance of 6 m to the next
well.
4. It should be safeguarded against flooding. Especially near rivers, the location has to be
chosen so that the well is not threatened by any meandering of the river. Furthermore, the
danger of flooding of low-lying areas should be taken into account.
5. The subsoil should not render the construction of a well impossible. It is difficult to make
hand dug wells in rocky materials, even if these contain sufficient quantities of water in
cracks.
B) Geological Guidelines
1. Layers of sand and gravel are the best aquifers.
2. In karstified limestone, the danger of pollution of groundwater from the surface is very
great.
3. In granite areas, weathered rock may contain good aquifers.
4. In mountaineous areas, the best aquifers are found along the edges of the valley.
5. Good aquifers can be found under the riverbed and in the river banks (i.e. in “buried”
rivers) or at lake sides.
204
6. Outcropping granite hills in connection with small dry valleys and depressions are
promising areas.
7. Crushed zones at fault lines (fractures, folds) are very good water bearing layers.
8. Vegetation such as banana trees, date palms, sugar cane, ever green areas, indicates
shallow groundwater (0-5 m).
9. Vegetation such as mango trees, nim trees, etc., indicate deeper groundwater.
10. Certain vegetation (certain trees, grasses, salty taste of sugar cane) indicates salty
groundwater.
11. Deposits of clay suitable for making pots can indicate near ground-water.
C) Methods for Well Siting
The following methods can be used for well siting:
1. Gathering information from existing wells
2. Gathering information from local well diggers
3. Hand augering
4. Divining
5. Well siting with instruments like resistivity meter, seismograph, etc.
6. Evaluating groundwater maps
7. Evaluating aerial photographs
8. Evaluating satellite photographs
The first three methods will be mostly available for small water projects. Good water supply
technicans continuously gather information when they come across wells and, thus, gradually
develop a feeling for soil and groundwater conditions, geology and vegetation. We also need
to build up a respectful relationship with local well diggers and thus share knowledge and
benefit from their rich experience.
8.13 Site Survey by Hand Augering
Hand augering is drilling a small diameter borehole by hand. It is a helpful tool amongst
others for selecting a suitable location for a hand dug well (see also 8.12/2). The method is
comparatively cheap and simple. It can be learnt quickly and does not require complicated
equipment.
205
Hand augering is not possible under all circumstances. The limits depend on the hardness of
the soil, the depth of the water table, and the perseverance of the technicians.
If the water table cannot be reached by hand augering, it might still be possible to construct a
good hand dug well - the water table might be just below the reach of the hand auger.
A) Purpose of Hand Augering
Hand augering can be used for gathering the following information:
1. Presence or Absence of Groundwater (within the reach of the augering);
2. The Depth of the Water Table;
3. The Thickness of the Aquifer (= water bearing layer);
4. The Nature of the Aquifer: the type of soil of the aquifer, its content of gravel, sand, clay,
and silt, and, thus, the permeability of the soil;
5. The Possible Recharge Rate (= yield) of the well, concluded from the permeability of the
aquifer soil;
6. Water Quality (salty or not salty, etc.);
7. Possible Movements of the Water Table, concluded from the colours of the augered
material;
8. Minimum Depth of the Well, concluded from the depth to hard rock or the first
impermeable (= impervious) layer.
9. Possible Storage Capacity of the well, concluded from the depth to hard rock or the first
impermeable layer;
10. Suitable Construction Method for the well, concluded from the thickness of the soil
layers and their stability; (Is temporary lining or caissoning necessary? How thick is an
eventual sand layer?); see also 8.14;
11. Presence of Single, Invisible Rocks Underground: in some areas single blocks of rocks
are dispersed above and underground - if you hit such an underground rock, a well site
suitable for digging might be just a few metres away;
12. Investigation of an Extended Area, like a river bank by augering a number of holes in a
systematic way;
13. Presence of Water Table below a Dry Well by drilling inside the already dug and so far
dry well.
B) Selecting Location and Time for Hand Augering
We will waste energy if we just start to drill holes without previous planning. Consider the
following:
1. Collect all available information (see 8.12).
2. Study the map and see where there would be the best sites for augering.
3. Have a careful look at the area on site before you start augering.
4. Preferably drill when the soil is wet. Drilling in completely dry clay is very difficult.
206
5. If necessary, drill a systematic net of holes over a certain area, e.g. every 100 m:
C) Hand Augering Equipment
Light weight hand augering sets can drill small holes of 5 or 7 cm diameter. Heavy weight sets
can drill larger holes up to 10 cm diameter or even more. These types differ in the diameter of
the bits, the thickness and strength of rods, handles, the type of couplings, and the number of
people required; but they consist of the same elements and are to be handled in the same
way.
A set of hand augering equipment consists of the following elements:
1. Handle
The handle can be extended by short pipes to increase the lever arm. The heavy weight set
can be drilled by two or more people.
2. Extension Rod
207
Usually, extension rods are 1 m long. A sufficient number is required. The rods can be
connected either by a bayonet coupling for light weight sets or threaded couplings for heavy
weight sets. The threads are protected by thread protectors when stored.
Bayonet Coupling:
Threaded Coupling:
3. Open Clay Auger
The auger body of the open clay auger (= combination bit = combination auger) consists of
two blades, the ends of which are forged into the auger’s end. Upwards the blades diverge
gradually up to the desired diameter. Depending on the width of the blades, the auger is
suitable for clay, sand or coarse sand if the soil is very soft.
4. Flight Auger
This bit is made of a steel strip wound around the central rod in a spiral form. It is suitable for
soft soils.
208
5. Stone Auger
The stone auger resembles the open clay auger, but the blades are longer. The bit is suitable
for weathered rock.
6. Stone Catcher
The stone catcher is made from a strong rod, curved in spiral form. It is suitable to catch
stones and gravel embedded in clay soil.
209
7. Screw Auger (= Spiral Auger)
This bit is made of a steel strip, forged in a spiral form. The diameter is smaller than the one
of the other bits. With this bit hard layers can be broken loose and the material brought out
with other auger types afterwards.
8. Riverside Bits
The auger body of these bits is a tube with two blades welded at the bottom. The sharp
extremeties of the blades point at an angle downwards, a little outside the tube. The blades
are spoon-shaped so that the soil is steadily pushed into the tube. This bit is suitable for use
in hard, stiff soils and in all kinds of materials below water level.
210
9. Bailer (= Pulse Auger)
The bailer is a 60 cm long tube fitted with a valve at the bottom. It is used for penetrating
saturated layers by moving it up and down or for dewatering the hole for test purposes.
10. Auger Cleaner
The auger cleaner resembles a knife and is used for cleaning the augers.
211
11. Meter
A water level meter has a plumb with a small cave in the bottom which produces a sound
when reaching the water table in the borehole.
12. Diverse Tools
such as spanners, hammer, wire brush, nylon brush, oil, grease, etc.
13. Equipment for Recording
such as writing pad, paper, pencils, forms, etc.
212
14. Tool Box
big enough for all parts of the equipment, including list of the contents of the tool box.
15. Sample Box
A sample box is a coverless, long and narrow wooden box, divided into a number of
compartments. During the drilling, a sample of each 50 cm is placed in the box to prevent
mistakes in the description.
D) Step-by-Step Procedures of Hand Augering
For hand augering, follow these steps:
1. Connect the handle, a rod and a bit.
2. Drill by one or several people (for heavy weight set).
3. When drilling becomes hard, remove the auger and clean it.
4. Drill again. Continue in this way.
5. When the rod has almost disappeared into the hole, add another extension rod.
Continue in this way.
6. Change the bits according to the soil type.
7. Never force the auger; if it will not turn with ease, change to a more suitable bit, e.g. the
screw auger for breaking the material loose, and remove the soil with another auger.
8. Keep the threads always clean and greased. For storing, always protect them with a
thread protector.
9. Put samples into the sample box every 50 cm.
10. Record any changes in the soil in a log (example for a well log see under E).
11. Try to drill as deep into the water table as possible.
12. If pumping equipment is available, make a test pumping.
13. Otherwise, dewater the hole with a bailer (= bail out the hole). Record the number of
times the hole needs to be bailed and, thus, the number of litres you have bailed out.
213
14. If the hole goes dry, measure the depth of the water in the hole at 5 minutes intervals
to gain the recharge rate.
15. After finishing augering, clean, dry and oil the equipment.
16. Record the water table after few hours.
17. Complete the records.
E) Hand Augering Log
Keeping careful records is much easier with the help of forms: Fill the form, “1. General
Information”, immediately after augering. Fill the form, “2. Soil Profile”, during augering.
Whenever there is a change in the soil, measure the depth. Draw a horizontal line on the
form, “Soil Profile”, at the measured depth. Note down all the information about the soil above
this level also above the horizontal line. When you take a soil sample, record its number.
Cross which type of soil you found, cross which colour it has, and cross if it is permeable or
impermeable. Record all the information about the next soil layer below the horizontal line.
Continue in this way for all the layers in the borehole.
Sudan Council of Churches * Munuki Water and Sanitation Project
HAND AUGERING LOG
Well No.
Community/Owner
Location
:
................................................................................................................
:
................................................................................................................
:
................................................................................................................
1. GENERAL INFORMATION
Auger hole No.
Location of the hole
Date of augering
Season
Time started
Time ended
Total time needed
Vegetation
Special vegetation
Bits used
first wet soil
first water table (WT)
Test bailing
rainy season
dry season
no vegetation
grass land
grass
and
bushes
thin forest
thick forest
open clay auger
flight auger
stone auger
stone catcher
screw auger
riverside bits
m
m
Number of bailers
Volume of bailer
W. Table after 5 min
10 rain
15 rain
20 min
25 min
30 min
WT after... hours
Water
Damages of equipment
Number of people
Technician
resp.
Signature
214
does not go dry
goes dry
litres
m
m
m
m
m
m
m
clear
turbid
no smell
bad smell
not salty
slightly salty
very salty
2. SOIL PROFILE
Auger hole No. ...............
F) Evaluation of Hand Augering
The evaluation of hand augering requires experience. However, consider the following
aspects when filling in the form, “HAND AUGERING EVALUATION” (see 8.13/12):
1. If you have drilled several holes for locating one well, choose the hole with the thickest
aquifer as well site.
215
2. The water table measured after few hours is the static water table for the season at the
time of augering.
3. Conclude from the colour of the augered material on the expected change of the water
table between the seasons:
- Reddish soils are well drained and well aired. Such layers are most likely not below
the water table at any time.
- Yellowish soils indicate that the soil is full of water for long periods. Such layers might
be below water table for a part of the year (during rainy season).
- Bluish colours in dark grey soil indicate that the soil is water-logged most of the time similar to the yellowish soils.
- Black and dark grey soils are usually badly drained and, therefore, likely to be
permanent below the water table.
Also, consider your knowledge about the change of the water table during the seasons in
the area; generally, the deeper the water table, the less is the seasonal change. Seasonal
changes of several metres are more likely in shallow wells (but they must not necessarily
be as great).
4. Conclude from the aquifer’s soil type and the thickness the expected recharge rate. The
coarser the material, the easier it will release its water content.
5. Judge whether the water is expected to be drinkable or not, considering the salt content.
6. Conclude from the depth of hard rock or the first impermeable layer how deep the well
must be. It is advantageous to dig 0.50 m or 1.00 m into these layers, if possible. Add
about 0.40 m for the well head. Divide the minimum depth by 0.85 cm, the nominal height
of a concrete ring, to get the required number of rings. Add one or two rings to be on the
safe side.
7. Determine the required number of filter rings by looking at the expected height of the
water column in the well.
8. Decide which diameter is suitable (see also 8.10/4 and 8.16/6).
9. Suggest a suitable construction method according to the stability of the soil in shaft and
intake (see 8.14).
216
10. Suggest a suitable water lifting device according to the expected depth, recharge rate
and the social circumstances (see 8.29 and 8.24).
Sudan Council of Churches * Munuki Water and Sanitation Project
HAND AUGERING EVALUATION
Well No.
:
................................................................................................................
:
................................................................................................................
:
................................................................................................................
Community/Owner
Location
Auger holes No.
expected stability
of well shaft
Well location suggested at hole No......
Static Water Table
... m dry season
... m rainy season
expected stability
below water table
Aquifer soil type
medium
low
good
medium
low
Aquifer thickness
Recharge
expected
good
m
rate
Water quality expected
minimum depth of well
total No. of rings
fully concrete rings
filter rings
diameter suggested
expected water storage
capacity
prepared by:
construction
method
suggested
high
medium
low
drinkable
not drinkable
m
water
lifting
device suggested
pcs
pcs
pcs
m
... m or... rings
V =.....m3
Remarks:
Date:
Signature:
8.14 Construction Methods for Hand Dug Wells
There are many different ways to construct a hand dug well. The following overview should
help to select the suitable method for a specific situation. You might be forced to use different
methods for wells within the same area.
A) Types of Lining
The lining of a well is a layer of material added to the inside surface of a well. The lining
serves the following purposes:
- It prevents the well from collapsing.
- It protects people working inside the well.
- In the bottom section (= intake), it allows water to enter the well.
217
- In the top section (= shaft) it prevents contaminated surface water from entering the well.
- It serves as a foundation for the well head.
The most important types of well lining are:
1. No Lining at All
No lining at all is, of course, the cheapest and simplest possibility, but only under suitable soil
conditions like hard rock or, above the water table, in very hard clay.
2. Lining with Masonry
Masonry lining can be
- from bricks
- from stones.
Masonry lining is advisable if bricks or stones are easily available near by, and cheap.
However, more cement is needed for masonry than for concrete rings which, again, increases
the cost. A very important factor in the decision might be if masons are available locally who
are able to do brick lining, but no technicians for constructing a concrete lining are available.
A masonry lining is not as strong as a concrete ring lining. It also requires a soil which is
temporarily stable on its own until the lining is built up. In soft, sandy soil a masonry lining is
excluded for the above reason. The depth possible for masonry lining is limited because the
transport of materials gets much more difficult with increasing depth.
3. Lining with Concrete Rings
Concrete ring lining can be
- cast outside the well and lowered into the well later on;
- cast in situ (= inside the well).
Concrete lining is suitable in any soil condition. However, the equipment, the materials
(cement, sand, gravel, reinforcement) and the skilled labourers must be available at
reasonable distance and price. Lowered concrete rings are the best option for very deep
wells.
Other types of lining, e.g. timber shuttering, are of no importance.
B) Constructing a Collar
A collar is a short wall around the mouth of the well. It serves the following purposes:
- It protects the well mouth from being washed out and widened by rain.
- It protectes the well mouth from collapsing due to the work on top.
- It protects the well shaft during digging.
- It provides a firm and safe working place for the labourers at the well mouth.
It is advisable to build a collar whenever the well is expected to be deep and digging will need
a long time (for all methods described under C, except No. 5 and 7).
Construct the collar as follows:
1. Dig a pit wider than the well diameter:
218
2. Build the collar from bricks or stones in cement mortar:
3. Continue digging inside the collar:
SCALE 1:50
4. If there is a rock layer near, use it as foundation for the collar:
SCALE 1:50
C) Different Construction Methods
219
When constructing a hand dug well, different types of lining can be used separately or can be
combined. Different methods are briefly described and compared in the following (incomplete)
list:
1. Caissoning below Water Table and Concrete Ring Lining
For this method, follow these steps:
- Build a collar.
- Dig until the water table is reached. Stop at the first signs of water.
- Lower a ring.
- Dig into the water table inside the ring while the ring slides down.
- Lower more rings on top whenever necessary.
- Dig into the water table as far as possible.
- Line the whole well with concrete rings and backfill it.
SCALE 1:80
This method is suitable for soil types which are stable above the water table, but unstable
below the water table (such as clay, sandy clay, etc.). This method is very handy because it
allows easy and quick digging above the water table, but provides protection below the water
table. It allows for easily digging deep enough into the water. Constant observation is
necessary because of the risk of collapsing. It is most important to stop digging before
entering the water table because the soil becomes immediately soft and muddy when
saturated. It is very difficult to correct a ring askew in mud, rather than digging in a straight,
proper way from the beginning.
2. Lining after Digging
For this method, follow these steps:
- Build a collar.
- Dig the well until its bottom is sufficiently below the water table.
- Lower concrete rings to line the well below and above water table and backfill them.
220
This method is only suitable in soil types which are also stable below the water table. This is
the case, for example, for rock or weathered rock which is stable for the time being, but needs
a lining in the long run because of cracks or mud fill-ins. The method is very handy.
3. Completely without Lining
This method consists only of two steps:
- Build a collar.
- Dig the well until its bottom is below the water table.
This method is only suitable in pure hard rock, without major cracks or mud fill-ins. You have
no work with the lining, but digging itself will be very difficult and slow.
4. Caissoning with Two Rings and Brick Lining
For this method, follow these steps:
- Build a collar.
- Excavate 90 cm deep.
- Cast a ring in the hole with pipe moulds (see 8.16/7).
- Cast a second ring on top.
- Dig the well inside the rings while the rings slide down (= caissoning).
- Dig as deep into the water table as possible.
- Build a brick or stone lining on top of the rings and backfill it.
SCALE 1:80
221
With this method, it is easy to dig deep enough into the groundwater. No lowering equipment
for rings is required, only a wooden scaffold and a pulley and a mould for the rings. Therefore,
the method has advantages for very remote areas. Digging the full length of the well with two
rings caissoning is not very handy, but helps to dig straight. The method is only suitable in
soft, but stable soils, not in weathered rock or rock, because the rings tend to get stuck at the
slightest protrudings of rock.
5. Caissoning the Complete Length of the Well
For this method, follow these steps:
- Cast the necessary number of concrete rings.
- Place the first ring with cutting edge on ground level.
- Dig inside the ring until the ring has almost disappeared into the ground.
- Roll the second ring near by.
- Turn it over until it sits on top of the first ring.
- Continue to dig until the second ring has almost disappeared into the ground.
- Place the next one on top, etc.
- Continue until you are deep enough into the water table.
SCALE 1:80
With this method, it is easy to dig deep enough into the groundwater. No lowering equipment
for rings is required. The method is only suitable for wells up to about 6 m deep, in soft soil,
because the friction between rings and soil becomes too great and the rings would just not
move downwards anymore.
6. Telescoping
222
For this method, follow these steps:
- Build a collar.
- Dig inside the collar 15 to 20 m deep.
- Build a foundation in the bottom from concrete or stones in cement mortar.
- Line this section by lowering concrete rings of large size (or by masonry).
- Dig inside the lining until the water table is reached.
- Build a foundation in the bottom.
- Line the second section with concrete rings of medium size (or masonry).
- Lower rings of small size.
- Dig into the water table while caissoning.
Drawing see next page.
This method is suitable for very deep wells because it enables us to dig deep and it provides
more safety for the technicians. If there are rock layers in between, they can be used as
foundation. The method is obviously quite laborious. The diameter of the well below the water
table is narrow.
Telescoping can also be used for deepening an already existing well in order to increase its
yield, e.g. because the water table has dropped (see also 8.16/4).
Telescoping:
SCALE 1:80
7. Digging and Lining in Sections
For this method, follow these steps:
- Dig one section deep.
- Line the section with brick lining or concrete lining cast in situ (= concrete poured
between an inside mould and the well wall).
- Dig the next section (The lining above is held by friction.).
223
- Line it.
- Continue like this to the well bottom below the water table or dig into the water table by
caissoning concrete rings.
Drawing see next page.
This method is suitable in very unstable types of soil (e.g. sand). Sandy soil can be
provisionally stabilized by making it wet. The length of a section depends on the type of soil
and can vary between 50 cm and several metres. Digging in sections below the water table
can be continued if the water inflow into the well is slow and it is easy to keep the well dry
during construction. Otherwise, caissoning with concrete rings is advisable. The method is not
very handy, but might be necessary under certain circumstances.
For more details see No. 17 in the bibliography.
8. Selecting the Suitable Construction Method
The selection of the suitable lining and construction method depends on
- the soil conditions,
- the depth of the well,
- the materials available,
- the equipment available,
- the skills available,
- the prices.
However, the first two are the really decisive factors. Carefully select the suitable method
according to these criteria and the information given above.
Brick Lining in Sections:
Concrete Lining in Sections
SCALE 1:80
224
8.15 Well Digging Techniques
A carefully dug well
- is exactly round,
- has the same diameter everywhere,
- has exactly vertical walls.
Careful and exact digging has the following advantages:
1. An exactly vertical and cylindrical well is more stable and is in less danger of collapsing.
2. No unnecessary extra material has to be dug out and pulled out of the well.
3. Lining or lowering concrete rings is easiest if the well is vertical and cylindrical.
4. No unnecessary material has to be backfilled.
A) Digging without Lining
The following techniques will help you to dig a straight well:
1. Keeping the Measurements while Digging
It is advisable to set pegs in concrete in the ground or into the collar before starting digging
(see drawing below). Place a piece of timber with two holes on the pegs. Screw a hook into
the middle of the timber to mark the well centre. Use two sets of wooden crosses while
digging. First, dig roughly according to the short set; then trim the edges exactly according to
the long set. Example for big size rings: Short set 1.30 m; long set 1.45 m.
Alternative:
Drive a peg in the centre of the well bottom. Turn a measuring rod around it. Measure the
centre from the top with the plumb bob.
2. Digging the Well Shaft
When digging the well shaft, first roughly excavate a hole about 10 cm smaller than the
diameter of the well and about 50 cm deep. In a second step, trim the walls to reach the exact
diameter.
225
B) Digging with Concrete Rings
Digging inside concrete rings and allowing them to slide downwards during digging is called
“sinking a caisson”. It is done according to the following technique:
1. Steps of Digging
First dig a rough hole inside the ring, about 10 cm smaller than the inside diameter of the ring.
Dig it about 50 cm below the bottom edge of the ring. This can be done by unskilled
labourers.
In a second step, cut back in layers all around to the outside diameter of the ring. However,
do not start at one point and dig around clockwise, because this would cause the ring to sink
askew.
Cut small pieces always opposite to each other in this order:
Do not cut much beyond the outside diameter of the ring.
226
You can also cut like this:
When the weight of the ring is greater than the friction, the ring will slide down the whole
section. Before it slides, it announces itself by slight movement or a sound. Pay attention that
your feet or hands or a tool are not underneath the edge of the ring.
2. Checking the Position of a Ring
Whether a ring is askew or not can be checked either by checking whether the ring-wall is
plumb, or by checking whether the ring-top is level. We select the method according to the
circumstances. Plumbing is suitable if the top of the ring is occupied by equipment (like a
beam, sling, etc.; see 8.17/22) or if a column of several rings is to be checked. Levelling is
suitable whenever the top of the ring is free. For reading spirit level and plumb bob see
6.4/9ff).
When using either method, always look first for the “neutral points” which lay opposite each
other. The neutral points are where the spirit level or plumb bob are vertical along the ring
wall. A long spirit level laid on top of the ring through the two neutral points is level. Mark the
two neutral points with chalk or charcoal or mud. The lowest and the highest points lie in the
middle of the two neutral points on opposite sides. A spirit level laid across the top of the ring
through the lowest and the highest points shows the greatest slope.
227
Check the distance d which indicates by how many cm (or “fingers”) the spirit level is out of
level:
Mark the lowest point with a big arrow:
3. Straightening Askew Rings
When you know where the highest and the lowest points are, remove soil from beneath the
lowest point (up to the neutral points). Dig underneath and beyond the outside edge of the
ring. Then carefully dig soil away from underneath the highest point, but do not dig further out
from the ring than necessary. Such rings can gradually sink again into vertical position. This is
the case if the spirit level is vertical all around the ring.
Alternatively, you can check it with the plumb bob.
228
C) Possible Complications during Digging
Different complications can occur while digging a well. Two common ones are described in
the following.
1. Rock
The appearance of rock makes digging much more difficult. There are different possibilities
how to continue:
- to continue digging with heavy crowbars and drastically reduced speed;
- to leave the site and start new;
- to use more sophisticated methods like a compressor or blasting with dynamite; these
need special skills.
2. Quicksand
Water and sand entering the well in great speed is called quicksand. It is very dangerous
because it can hold your feet so that you are unable to pull them out. Additionally, it can fill
the well quickly or/and cause collapsing of the surrounding area. If you encounter quicksand,
leave the well immediately and remove all tools. It might be necessary to leave the site and
dig a new well nearby, planned in such a way as to caisson through the sandy layer as quick
as possible. Never enter a well with quicksand without safety belt and rope connection to the
top.
8.16 Manufacturing Concrete Rings
Lining wells with ready made concrete rings has the following advantages:
1. It is very stable.
2. It protects the diggers while “caissoning” into the groundwater.
3. It is thin and, therefore, requires less excavation.
4. The rings are easily prefabricated outside the well.
5. Finishing the well (i.e. lowering the rings) can be completed within short time.
6. Less cement is needed than for other lining like brick lining or stone lining.
The Disadvantages are:
1. Moulds and other equipment are needed for casting the rings.
2. Special equipment is needed for lowering the rings.
3. Skilled labour is necessary for lowering and caissoning.
229
A) Types of Concrete Rings
The following three types of concrete rings are needed to construct ordinary wells:
1. Fully Concrete Ring
- rebate on top and in bottom
- to be used in well shaft above water table
- prevents water from entering the well
2. Filter Ring
- rebate on top and in bottom
- to be used in well shaft under the water table
- allows water to enter the well
3. Filter Ring with Cutting Edge
- rebate on top, cutting edge in bottom
- to be used as the first ring in the well
- allows water to enter the well
- cutting edge makes digging easier
230
B) Application of the Different Ring Types
The different types of rings are to be utilised in a well as follows:
SCALE 1:50
231
The rings have rebates on the top and in the bottom edges. A rebate is a step-shaped
channel along the edge of the ring to receive the corresponding edge of another ring. On the
top edge of the ring, the channel is outside. This corresponds to the bottom edge of another
ring where the channel lies inside.
The rings have to be stacked on top of each other in such a way that no surface water can
enter the well through the rebates. They have to slope outwards. The moulds described in D)
produce rings which can only be stacked in the correct way if the first ring in the well is one
with a cutting edge.
The filter rings below the water table are just stacked on top of each other without mortar. The
rebates provide the connection. The fully concrete rings above the water table are connected
with cement mortar to make a watertight joint.
C) Sizes of Concrete Rings
It is advisable in a project to have moulds of different sizes for different purposes. The
dimensions should be chosen in such a way that the next smaller ring can be used inside a
previous ring when deepening the well becomes necessary later on. This is called
“telescoping”(see also 8.14/7f).
SCALE 1:50
232
The advisable height of the concrete rings depends on the equipment available for lowering
them into the well. Rings 50-60 cm high are light and, therefore, can be lowered with light
weight equipment. Small rings also cause fewer problems during transportation if
manufactured in a central workshop. But they require more reinforcement. The work progress
during lowering is slower and more joints need to be constructed. For very deep wells small
rings are not advisable.
Concrete rings 90-100 cm high are heavy and require strong, more expensive and heavier
lowering equipment. If this equipment is available, high concrete rings are preferable,
because of the easy manufacturing process and quicker work progress during lowering. If
rings are to be manufactured on site, this height is advantageous. Rings higher than 100 cm
are not advisable at all.
The thickness of the wall of a concrete ring should be between 6 and 10 cm, depending on
the diameter of the ring. A wall thinner than 6 cm cannot accomodate the reinforcement
properly and will break easily; a wall thicker than 10 cm makes the ring too heavy without
adding to the strength accordingly and is, therefore, a waste of material.
The following sizes for concrete rings are suggested for a water project:
(All rings are 0.92 cm high.)
1. Large Size:
- big water reservoir can store large quantities of water
- more digging is necessary
- 2 or 3 people can dig in the ring at the same time
- it is suitable in soft soil and if the water table is not too deep
2. Medium Size:
- a moderate water reservoir
- less digging is necessary
- 1 to 2 people can dig in the ring at the same time
- usually used
- suitable also in deep wells and in rock
- suitable for telescoping within a large ring
233
3. Small Size:
- small water reservoir
- little digging is necessary, but digging is difficult due to little space
- only one person can dig in the ring
- suitable only in special cases
- suitable for telescoping within a middle size ring
SCALE 1:30
D) Pipe Moulds
Pipe moulds are steel forms for casting concrete rings. They are very durable, can last for a
long time, and produce rings which always have the same size and shape. However, they
need to be handled with great care.
Pipe moulds consist of the following parts:
1. Inner Mould (with two pieces and wedge)
234
Inner mould without wedge:
LAYOUT PLAN:
If the inner mould has no wedge, but consists of two pieces similar to the outer mould, you
must place a piece of timber 1”×2” in between the parts of the inner moulds. Otherwise, you
will not be able to remove the inner mould after casting the ring without breakage.
2. Outer Mould (two pieces)
design: Harrtz & Bell, Nairobi
SCALE 1:25
235
3. Base Plate for Rebate
4. Base Plate for Cutting Edge
5. Cutting Cross (for cutting rebate on the top of the ring)
E) Casting Concrete Rings
Manufacture concrete rings according to the following steps:
236
No.
1
Step
Load and unload the moulds very care fully.
Avoid dropping them and bending them out of
shape.
2
Place the base plate on level, clean ground.
3
Place the inner mould inside the base plate.
Check if the wedge can be pulled out easily;
otherwise, clean and grease it. Check if the
mould can be easily hinged inwards.
Bend the reinforcement around the mould; cut
it and tie it using the appropriate diameter:
4
One reinforcement in one layer for rings Ø
1.07 m:
5
6
Reasons
Out-of-shape moulds produce rings
which are not round. They do not fit
into each other when lowered into the
well.
This ensures easy compaction and
minimizes movement.
After concrete is cast, the moulds are
much more difficult to move.
The reinforcement should never touch
the moulds but be well covered by
concrete from all sides. Concrete
prevents steel from corroding. See
6.6/8ff.
Two reinforcements in one layer for
rings Ø 1.40 m:
Take the reinforcement out.
Paint the base plate, the inner mould
(outside), and the outer mould (inside) with old
engine oil.
Place the outer moulds and connect them with
locking bars. Check if the mould is in correct
position all around.
It will be needed later on.
Engine oil prevents the concrete from
sticking to the steel mould (like oil
when baking bread).
The correct position on the base plate
assures that the mould is really in a
round shape. It should not sit on the
hollow circle shaped steel plate.
9
Place the cutting cross on the mould and
check if you can easily turn it.
Wash the gravel if necessary.
10
Sieve the gravel if necessary.
11
Mix the concrete thoroughly. For mixtures see
F). Mix cement and sand dry. Then add water
and mix thoroughly. Add as little water as
possible. Add gravel, and mix thoroughly. The
water content is correct if the concrete is just
workable for pouring and compacting. The
concrete should look dry. If compacted a little,
water needs to appear on the surface.
The round shape of the mould can be
checked with the cutting cross.
Soil particles make the concrete
weaker. See 6.6/7.
The biggest parts shall not exceed 20
mm diameter.
Only a well mixed concrete is strong.
The cement needs to be evenly
distributed inside the concrete. The
concrete is weaker if there is too much
water in it. See 6.6/7
7
8
237
No.
12
Step
Pour a little concrete into the mould evenly all
around. Compact it with wooden stampers.
Reasons
This ensures that the concrete is
compacted evenly. All air bubbles need
to be removed, because they make the
concrete weaker.
13
Fill to about 10 cm high all around. Place the
reinforcement.
Take
care
that
the
reinforcement does not touch the moulds.
Fill the mould, layer by layer, and compact
each layer.
When the mould is filled 80 cm high, place the
reinforcement.
Fill the rest of the mould. Compact it well. Cut
the top rebate with the cutting cross. Remove
the surplus concrete.
Fill in some cement mortar 1:4. Cut again with
the cutting cross.
Write the date into the fresh concrete.
The top and bottom reinforcement
prevent the rings from breaking.
14
15
16
17
18
19
Wash away all concrete spilled outside on the
moulds.
20
Cover the mould.
21
Remove the moulds (without the base plate) 3
hours after casting at the earliest. Lift the
wedge of the inner mould. Hinge the inner
mould inwards and carefully remove it. Open
the outer moulds and remove them. Clean the
moulds immediately.
22
Cover the ring with wet sackcloth and nylon (or
wet grass). Or water it continuously. Keep it
wet for at least 3 days, better for 7 days.
Remove the base plate after 2 days (48 hours)
at the earliest. Place a “cushion” of sand
beside the ring. Pull the ring over on its side by
a sling. Remove the base plate. Clean it. Let
the ring down again. Cover the ring again.
23
24
After three to four weeks the rings are hard
enough to be lowered into a well.
238
The ring must be well compacted
throughout for high strength.
see No. 13
The top and bottom rebates are
corresponding and ensure a strong
connection between the rings.
The rebate becomes smoother if
cement mortar is used.
If the date is recorded, you know if the
ring is hard enough for lowering. See
6.6/6f
Otherwise the concrete will get hard on
the mould. It will be difficult to clean it
later. Old concrete makes the mould
heavier.
Fresh concrete becomes stronger if
kept wet (= cured).
Take care not to damage the fresh
concrete. The outer mould still protects
the ring when removing the inner
mould first. The concrete is of good
quality if the surface is smooth without
air bubbles. It is easier to clean the
moulds immediately when they are still
wet.
Curing the concrete by keeping it wet
prevents cracks and makes it strong.
If 48 hours have not yet passed, the
rebate is not hard enough and could
easily be damaged. If you pull over the
ring before time, it would crack or
break.
To lower them before is a danger to
the workers and can cause heavy
losses of time and material. See 6.6/6f.
F) Mixtures and Reinforcement
Use a strong mixture of 1:3:4 for fully concrete rings to compensate for ingredients of variable
quality and mistakes in work. Even if cement is very expensive, the safety of the workers is
much more important than minimizing cement costs. Breaking of rings at any stage (during
moving, lowering or digging) can easily cause bad injuries.
The same mixture 1:3:4 is used for the bottom and the top of filter rings. Together with the
reinforcement this gives strength to the filter ring. In spite of that, the filter ring is weaker than
the fully concrete ring and, therefore, needs to be handled with even more care. The filter part
consists of a mixture 1:0:4 (one part cement, no sand, four parts gravel). The voids between
the gravel make the concrete porous and allow the water to enter through the filter ring.
Alternatively, a mixture of 1:1:4 could be used. When mixing concrete for the filter part, mix
the cement with water first and add the gravel afterwards.
For medium size rings, 2 reinforcement rods, 0 8 mm, all around the ring, one in the bottom,
one on the top, are sufficient, both for fully concrete and for filter rings. Add another ring of
reinforcement in the cutting edge.
If reinforcement is not available, it can be substituted by one layer of chicken wire all around
the ring. This is only possible for fully concrete rings; it also makes compacting more difficult.
To substitute the reinforcement by welded mesh all around the ring is very expensive.
Alternatively, you can cut 2 stripes of welded mesh:
Middle size rings might also be manufactured without any reinforcement at all (only fully
concrete rings!), although it is not advisable. In that case, the mixture must be stronger, the
curing must be continuous for seven days, and rolling the ring is very delicate. Casting rings
without reinforcement should only happen in emergencies. You run the great risk of loosing
the whole cement through breakage of the ring.
For large size rings, 4 reinforcement rods, Ø 8 mm, are necessary, 2 in the top, 2 in the
bottom. Add another reinforcement in the cutting edge. The reinforcement can be substituted
by 2 layers of chicken wire or 1 layer of welded mesh all around the ring. Large size rings
cannot be manufactured without reinforcement.
The above instructions are valid only for rings which are to be turned over, rolled and lowered
into a well. Rings cast in situ (on the site), for example for water tanks, which are never to be
moved, can be cast without reinforcement. See also 6.6/10.
On the other hand, rings to be used as culverts (= channel carrying water under a road) need
much stronger reinforcement. They have to bear the load of cars and lorries driving over
them. The reinforcement depends on the type of cars using that road and the thickness of soil
between the culvert and the road. The reinforcement must be at least one layer of welded
mesh, but could be as much as 1 reinforcement 0 10 mm every 10 cm. See also 6.6/10.
Mixtures, approximate quantities and reinforcement for well rings are compiled in the following
table:
239
Ring
Size
Ø
1.40
Type of Ring
fully concrete ring
1:3:4
Cement
Buckets
5
filter ring,
1:3:4
1
3
4
4Ø8
1:0:4
1:3:4
5
1
0
3
20
4
-5Ø8
1:0:4
1:3:4
5
3
0
9
20
12
-2Ø8
and
1:3:4
1
2
1
2
2
2Ø8
filter part
top
and
bottom
1:0:4
1:3:4
12
2
-3Ø8
filter part
1:0:4
12
--
filter
ring
with cutting
edge
Ø
1.07
Mixture
top
and
bottom
filter part
top
and
bottom
filter part
fully concrete ring
filter ring
filter
ring
with cutting
edge
top
bottom
Sand
Buckets
15
Gravel
Buckets
20
Reinforcement
Rings
4Ø8
1
3
0
1
2
1
1
2
3
0
1 bucket is about 10 lit. 1 bag of cement is about 3
1
buckets.
4
8.17 Lowering Concrete Rings into a Well
Concrete rings are heavy; the middle size weighs about 540 kg, the large size weighs about
940 kg. Lowering them into a well is a delicate work and requires skilled technicians and
reliable equipment. See also 5.7.
A) Methods of Holding a Concrete Ring
Concrete rings can be held for lifting and lowering by different methods:
1. Tying the Ring with Rope
Step-by-step procedures:
- Sling a rope underneath the ring and tie it around the ring walls.
- Do this on 3 or 4 spots around the ring.
- Lift the ring.
240
Advantages:
- Nothing else other than rope is needed.
Disadvantages:
- The method is not very handy.
- The ropes wear out very quickly.
- The ropes are difficult to remove once the ring is placed on top of another ring.
- It is not easy to balance the rings horizontally.
2. Tying to Hooks in the Ring
Step-by-step procedures:
- Tie 3 or 4 hooks made from steel Ø 10 mm to the reinforcement before pouring the
concrete into the ring moulds.
- Cast the hooks into the concrete.
- When you want to lower the rings into a well, tie ropes to the hooks.
- Lift the ring.
Advantages:
- The connection is strong.
Disadvantages:
- Extra work is needed when casting the rings.
- Rebates are not possible.
- The next following ring will not sit properly on the previous one because of the hooks.
More mortar is necessary.
- If the hooks are to be bent inwards after lowering, the concrete can break easily.
3. Holding by Steel Hooks
Step-by-step procedures:
- Manufacture three steel hooks from reinforcement Ø 20 mm.
241
- Grasp the bottom edge of the ring with the three hooks.
- Tie the eyes of the hooks together and lift them at a go.
Advantages:
- The equipment is simple and can be manufactured locally.
- The method is relatively handy.
- Little space is needed outside the ring.
- No hooks have to be cast into the concrete.
Disadvantages:
- The method is only suitable for small, light weight rings (up to Ø 1.10 m and 60 cm
height).
- It is difficult to balance the ring during lowering.
- The bottom rebates can be easily damaged by the hooks.
- It is difficult to get the hooks out, once the ring is placed on top of another.
- There is little working space for the technician on top of the ring.
4. Holding by Steel Cable
Step-by-step procedures:
- Prepare a strong hook from double flat iron, 60 x 8 mm, (or from car springs) by
blacksmithing and welding.
242
- Prepare a steel cable with an “eye” on one end and the hook from flat iron on the other
as follows:
The total length (including the hook and the eye) should be about
l = h + π × D + 1.41× D = h + 4.55 × D
h = height of concrete ring
D = diameter of concrete ring
π = 3.14
Cut the steel cable. Weld its ends by gas welding to prevent splitting and injury to people. Fix
the hook and the eye, each with two wire rope clamps.
- Prepare a piece of timber 2” x 4”. The length should be:
l = D + 3 cm
Cut a slight groove into its ends and reinforce it with iron band as shown:
- Once the steel cable and the piece of timber (= “beam”) are made, they can be used
243
many times.
- Fix the steel cable with the beam around the ring like this:
The beam prevents the cable from cutting and damaging the concrete. The cable should be at
the middle of the ring or below.
- Lift the ring with a swivel-hook. The sling is able to lift the heavy concrete ring through
friction between cable and concrete.
- If not balanced, put down the ring again and move the swivel-hook accordingly until the
ring is balanced.
Advantages:
- The equipment can be produced locally.
- No hooks have to be cast into the concrete.
- Any type of ring can be lifted, with or without rebates.
- The ring is held in the middle and all around.
- The method is very handy, quick and safe.
- The rings are easily balanced and directed during lowering.
- Only little space is occupied outside the ring.
- There is nothing underneath the ring; the ring can be placed directly on top of another
ring.
- There is enough working space for the technician on top of the ring.
- The equipment is long lasting.
Disadvantages:
- Steel cable and iron hook are needed.
(In emergency cases triple rope can be used instead of steel cable.)
5. Holding by Self-Locking Lifting Clamps
244
Special lifting clamps are industrially available for lifting concrete rings. They consist of three
clamps attached to chains. When pulling the chains, the clamps automatically tighten and
hold the ring by friction. They are “self-locking” when pulled.
Step-by-step procedures:
- Place the three clamps on the ring at equal distances.
- Lift the ring by the chain.
Advantages:
- The method is very handy and quick.
- Any type of ring can be lifted.
- The rings are easily balanced.
- There is nothing underneath the ring.
Disadvantages:
- The special lifting device is not easily available and cannot be produced locally.
- The clamps require space outside the ring.
- The ring is held only on three small spots; if the concrete is of weak quality, it can break
and the method is not safe.
- There is little working space for the technician on top of the ring.
6. Selecting the Suitable Method
The selection of the suitable method depends on the circumstances and the equipment
available. whenever possible it is advisable to use method No. 4.
B) Methods of Lowering a Concrete Ring into a Well
Concrete rings can be lowered into a well by different methods:
1. Lowering with Local Equipment
The equipment necessary for this method should be available locally and/or within the
country.
Step-by-step procedures: see also drawing 6.17/9
- Erect 4 strong Y-shaped poles (“shebas”) around the well and fix them in concrete.
245
- Lay 2 strong metal pipes, Ø 2½, or strong poles, across them and tie them to the shebas.
- Lay three strong, long poles, or pipes Ø 2½, across the mouth of the well.
- Place the ring on top of these poles or pipes outside the well mouth.
- Tie four pulleys on the crossing pipes.
- Pull four long sisal ropes Ø 25 mm through the four pulleys.
- Tie the ring with the four ropes by method 1 or 2 as described under A).
- Let about 8 to 10 people pull at each rope.
246
- Lift the ring and let it slide into the middle above the well.
- Remove the poles from underneath.
- Lower the ring into the well.
Advantages:
- No sophisticated equipment is necessary; most of it is available in the village. Pulleys,
pipes, ropes should be available within the country.
Disadvantages:
- Very much rope of good quality is required. The rope wears out quickly during lowering.
New ropes are required for each well which is very costly.
- Many people (about 40) are needed for lowering rings. It is difficult to get the required
number of people (adults!) continuously for the necessary period of time and it is also
difficult to coordinate such a number of people. Some will be redundant in between while
the technicians work in the well.
- Precise lowering and balancing of the ring is difficult with this method.
- Rings cannot be lowered deeper than 15 m by this method.
Lowering a Concrete Ring with Local Equipment
247
ISOMETRIC VIEW
2. Lowering with Light Weight Tripod and Pulleys
Only light concrete rings (maximum Ø 1.10 m, height 60 cm) can be lowered with a light
weight tripod consisting of three metal pipes, Ø 2”, 3 m long, connected with a steel cable.
The weight of the ring is lifted by a tackle.
Tackles
A tackle (= “block and tackle” or “pulley system”) is an assemblage of ropes, pulleys, and
hooks to lift weights, arranged to gain mechanical advantage for hoisting and pulling. For
tackles, four different parameters (= features, characteristics) are to be considered:
l = lift or distance the item has to be lifted;
d = distance the rope is to be pulled to gain the lift ( l );
W = weight of the item to be lifted;
F = force needed to pull the rope in order to lift the weight
248
They are connected as follows:
If the distance you pull the rope (d) is a multiple of the lift ( l ) by the factor (a), then you need
to pull with a force (F) which is the weight (W) divided by the same factor (a):
d = l×a
F=W×
1
= W ÷a
a
Check how many rope connections there are between the two pulley blocks. This number is
the factor (a), because each rope connection has to be shortened by the lift ( l ).
Applied to the three most simple tackles, this means:
One Pulley Block
249
d= l
F=W
You pull the same distance as you lift an item.
You pull with a force as big as the weight of the item.
No mechanical advantage.
Two Single Pulley Blocks
d=2x l
F=
1
xW
2
There are 2 rope connections between the two pulley blocks.
You pull twice as long as you lift the item.
You pull with a force half of the weight of the item.
Two Double Pulley Blocks
250
d=4x l
F=
1
xW
4
There are 4 rope connections between the two pulley blocks.
You pull four times as long as you lift the item.
You pull with a force a quarter of the weight of the item.
Use this information for calculating the length of rope needed and the number of people
requested for a certain task.
Example:
A 400 kg heavy ring should be lowered into a 6 m deep well by a tackle with 2 double pulley
blocks.
factor of the tackle
distance between ground level and pulley
lift + distance to head of tripod
length of ropes in the tackle
extra rope from pulley to people
length of rope required
weight
force for pulling rope
a=4
2m
l =6m+2m=8m
p = 4 × 8 = 32 m
10 m
L = 32 m + 10 m = 42 m
W = 400 kg
approximate pulling capacity of one person
25 kg
F=
251
1
x 400 kg = 100 kg
4
number of people required
100 kg
= 4 people
25 kg
Note:
The lift of a tackle is not unlimited! Beyond a certain length, the item lifted tends to turn along
its axis, thus twisting the ropes of the tackle around each other. This danger is even greater if
the rope is new. Once the ropes are twisted, it is hardly possible to unwind them and they
might even break.
Step-by-Step Procedures for using light weight equipment:
- Place the tripod over the well. All three legs must be in equal distance from each other:
a=b=c
Check with a measuring tape.
- Fix a tackle with two double pulleys on the tripod.
- Connect the rope with the ring with method 1, 2, 3 or 4 of A (see 8.17/1ff).
- Lift the ring and pull it to the centre of the well mouth.
- Lower the ring.
Advantages:
- The equipment is very simple and can be manufactured locally.
- The equipment can be transported from site to site easily.
- The equipment can be erected quickly and with few people.
- The method is handy.
Disadvantages:
- The method can lift only light weight rings.
- This method can be used only for wells up to about 15 to 20 m deep. Below this, there is
great danger of twisting the tackle cables.
- The method cannot be used if the mouth of a well is completely washed out (because
such a small tripod cannot span a big opening).
252
- Very long rope is required.
- The rope wears out quickly.
3. Lowering with Heavy Duty Tripod and Winch
Concrete rings can also be lowered with a heavy duty tripod and a hand operated winch with
steel cable. The equipment is described in detail under C (see 8.17/15ff).
Step-by-step procedures
see under D (see 8.17/20ff).
Advantages
- Any type of ring, even large ones, can be lowered.
- Rings can be lowered into wells up to 50 m deep.
- The method can be used even if the mouth of a well is completely washed out and wide.
- The method is very handy, quick and precise.
- It is easy to direct the rings inside the well.
- The number of people required is only about 10.
- The steel cable is durable and will not wear out quickly.
- The method is safer than methods 1 and 2.
- Part of the equipment can be manufactured locally.
Disadvantages
- A pick-up with roof-carrier is needed for transporting the equipment.
- Erecting the tripod and fixing the winch is rather time consuming and requires about 10
people.
- It is costly and difficult to purchase the equipment.
- If even only one part of the equipment does not function, the method cannot be used.
4. Selecting the Suitable Method
The selection of the suitable method depends on the number of wells to be constructed, the
average depth, the size of the rings and the availability of equipment. Whenever several wells
are to be constructed, a permanent tripod from metal pipes is advisable (method 2 or 3).
Method 2 is suitable in an area with shallow wells (up to 20 m) and with good roads. In that
case, small rings can be manufactured in a central workshop, transported to the site and
lowered there with light weight equipment.
In an area with bad roads, central manufacturing of rings is not suitable-Large rings can be
produced on site and lowered by method 3. For deep wells beyond 20 m and rehabilitation of
wells which have been washed out very much on top, only method 3 is possible. This method
is suitable for most conditions and is advisable if the size of the project and the financial
possibilities allow; it is described in more detail under C and D.
253
C) Heavy Duty Equipment for Lowering Rings
Heavy duty equipment for lowering concrete rings into a well consists of the following
elements:
1. Tripod
A heavy duty tripod consists of the following elements:
- 2 single legs, Ø 2
1
“ or Ø 3”, 6 m long
2
- 1 double leg from the same pipes, with steps
- head of tripod, connecting the legs, with an eye to hold the pulley
- device to take up the winch
Design: Van Reekum Materials, Netherlands
Check the connection between the legs regularly for damage.
Never load the tripod if one of the legs has even a slight bend!
Watch the tripod when you put it under load.
Tripods can be manufactured locally in a welding shop or purchased ready-made.
2. Steel Cable
Steel cable of Ø 10 nun is suitable for lifting concrete rings. It has a soft core with several
thinner steel cables wound around it.
254
If handled carefully, steel cable is very strong and durable.
Steel cable must always be wound up “under tension”. If necessary, provide the tension by
pulling the cable by hand while winding up. Never attempt to fold steel cable.
Steel cable is only strong if all parts are intact.
Never use steel cable for heavy loads if even one of the parts is split or broken.
After lowering several rings, the cable might be more twisted than usual due to the turning
movements of the ring. In this case, the cable tends to fold itself while not under tension:
In the long run, this spoils the cable at the fold. Never try to straighten the cable by force, but
untwist it carefully. Prevent folds by untwisting the cable from time to time.
Protect the ends of steel cables by gas welding. Otherwise, the cable will unwind itself and
get weak. The split ends of a steel cable can also badly hurt people.
Use two wire rope clamps (= cable clamps) and a thimble for the ends of a steel cable.
Tie the wire rope clamp firmly, but do not squeeze the cable. Tie the clamps in opposite
direction. See also 6.3/40.
3. Winch
A hand-operated winch for lifting concrete rings consists of the following elements:
- a drum for winding up the steel cable,
- a gear,
- two winding handles,
- a safety device which blocks if the load is suddenly released (= ratchet),
- a lever brake,
- a connecting device to the tripod (see 8.17/15).
Operate the winch with great care. There should be always at least one person at the winch
who is familiar with its operation.
Be alert that the safety device is operating at all times. You hear it by the continuous tak-taktak sound while lifting.
The safety device is to be suspended only during the actual lowering by a special handle. The
255
person holding this handle must be prepared to release it at any time in case of danger and to
brake at the same time. This handle must move freely and fall against the ratchet by its own
weight.
Make Sure that the gear is properly engaged.
The pin holding the cover must be well closed. If the cover gets loose, the gear can suddenly
disengage and release the load.
Sudden release of a load like a concrete ring is extremely dangerous. The well can collapse;
the ring will break; parts of the equipment may break; the handles of the winch will turn with
terrible speed and can hurt somebody very badly.
Do not load the winch suddenly. Use the brake to make the movements smoother and to
assist controlling the load when lowering.
For details of the winch see the picture next page.
Winch
Design: Van Reekum Materials, Netherlands
256
4. Shackles
The eye of a steel cable can be connected to a swivel-hook, a pulley, another steel cable, or a
load by the help of a D-shackle or a connecting link.
These connections are safe and can be quickly assembled and disassembled. The shackles
and connecting links are available in different sizes. The size has to be selected according to
the cable diameter and the load. See also 6.3/40.
5. Pulleys
Pulleys consist of the following elements:
- a wheel with a grooved rim to hold the cable or the rope
- an axle
- a frame holding the axle
- a swivel hook
- an eye
Clean and grease the pulley regularly. Check the hook and the eye. Make sure that the pulley
is carefully tied on the tripod and the cable is running smoothly on the wheel without rubbing
against other parts. See also 6.3/10.
6. Swivel Hook
A swivel hook (= lifting hook) is a hook from forged steel to lift a given load. Good swivel
hooks always have a safety catch. See 6.3/40.
257
D) Steps of Lowering Rings with Heavy Duty Equipment
When lowering rings with heavy duty equipment, follow these steps:
1. Erecting the Tripod
No
1
Step
Erect the tripod. The top shall be exactly over the
centre of the hole. The angle between the tripod
legs and the ground level should be about 45°.
Both single legs must stand at the same distance
to the double leg. The distance between the feet of
the single legs should be about 4 m. Measure the
distances between the legs with a measuring tape.
Dig holes for the feet of the legs.
Reasons
If the tripod is not properly erected, it
can tip over during the work and
cause damage and danger.
2
Fix the winch on the double leg and a pulley at the
top of the tripod. Standing behind the winch, the
cable must be seen hanging exactly between and
parallel to the legs of the double leg. from the other
side, the tackle cable must be in the centre of the
well.
Thus the centre of gravity of the ring
hanging on the tripod will be within
the three legs and will not pull the
tripod over.
258
2. Lowering the First Ring
1
2
3
4
Level the bottom of the well. Check with a spirit
level.
Lay three pipes Ø 3” across the hole, parallel to the
double leg. Role the ring near to the hole (position
No. 1) and turn it over into horizontal position (No.
2) with the help of a rope sling and enough people.
Be very careful. The ring should stand between the
two single legs.
The bottom must be level so that the
first ring will be level, too.
If the ring rolls into the well, it will
break and damage the well.
The cable sling is fastened around the ring with the
beam by method No. 4 in A. and attached to the
tackle cable. The beam shall be parallel to the
double leg. For middle size rings, a tackle with one
pulley block and one cable is sufficient. For deep
wells, lowering is only possible with one tackle
cable. For very shallow wells up to 8 m and large
rings, a tackle with two cables and two pulley
blocks should be used.
Pull the cable gently upwards and push the ring on
the pipes into the centre of the hole. Nobody must
ever be underneath a ring. Nobody should put a
hand or foot underneath a ring.
The beam prevents the top of the
ring from being crushed. The sling
provides safe lifting. In deep wells
the ring is bound to turn. Two cables
would twist around each other and
block.
5
Re-adjust the sling. Lift the ring and check if it
hangs horizontally.
6
Pull the pipes away from the hole.
7
Pay out (= release) the tackle cable and lower the
ring into the well until it reaches the bottom of the
well.
Nobody must sit on the ring while lowering.
Lower a technician into the well by a second pulley,
rope, and piece of wood (see 8.21/2). Check the
position of the ring with the spirit level (see in detail
8.15/4). If not exactly level, lift the ring slightly and
remove some soil from underneath until the ring is
exactly level.
Remove the sling from the ring and wind up the
steel cable.
8
9
259
The ring moves into the middle of the
hole in a controlled way.
Safety first. In case of an accident
the
ring
can
kill
somebody
underneath.
If the ring does not hang horizontally,
it can loose balance and it can get
stuck in the well.
They are not needed for loring, but in
the way.
In case of any failure, a person
sitting on the ring while lowering
would be in great danger.
A well is less stable if the walls are
not vertical. In a deep well, the top
rings will not fit, but touch the wall, if
the first ring is not level. To
straighten the rings later on is much
more difficult.
The swivel hook is heavy enough for
winding up the cable under tension.
3. Lowering the Rings below Water Table
1
Lower the next ring in the same way (repeat No. 2,
steps 2 to 6)
Pay out (= release) the tackle cable and lower the
ring until the ring has reached the previous ring.
You can direct the ring from the top by pressing a
pipe against the tackle cable in the desired
direction.
All rings are lowered in the same
way.
Sometimes the ring must be directed
because the well is narrow at some
spots.
3
Lower a technician into the well. She/he should sit
on the beam with the legs on both sides of the
beam against the walls of the well. The hands
should also lean against the wall. Lift the ring by
about 5 cm. While being lowered again, the
technician can direct the ring so that it is placed
exactly on the previous one, with the rebates fully
attached.
In most cases the ring will not get
placed automatically in the correct
position, but it must be directed. The
described position keeps the ring in
balance and enables the technician
to direct the ring easily.
4
Check if the ring is level. Remember the direction
of the neutral line (= connection between the two
neutral points). If necessary, correct by putting
sand or mortar between the rings on the lower side.
Remove the sling from the ring and wind up the
steel cable.
Continue to lower rings in the same manner. In
between you might need to dewater the well.
It is acceptable if the ring is out of
level by 0.5 to 1 cm, especially, if the
direction of the neutral line changes
with each ring.
2
5
6
7
If the cable is too much twisted after lowering some
rings, untwist it.
260
For
dewatering
construction
see
8.27,8.28.
See 8.17/16
wells
8.25,
during
8.26,
8
Backfill after stacking maximum 4 to 5 rings above
each other. Fill clean gravel between the rings and
the wall all around. This work becomes much
easier if you use plastic pipes Ø 4” and a funnel
and pour the gravel directly from the top evenly all
around. Take great care that the pipes are properly
connected and suspended and no gravel misses
the funnel.
261
The backfill prevents the rings from
horizontal movement and bears part
of the rings’ weight through friction. 6
or more rings put on top of each
other, without horizontal support, is a
very unstable and dangerous
construction.
It
might
cause
breakage, uneven sinking or tilting to
the side. Gravel backfill below the
water table allows the water to enter
the well.
A single stone, missing the funnel, is
a great danger for the technician
below.
4. Lowering the Rings above the Water Table
1
For rings above the water table, spread mortar on
the rebate before lowering the next ring.
2
3
Lower the ring. Repeat No. 2, step 2 to 9.
Lower a technician sitting on a bosun’s chair.
She/he should close the joint between the two rings
with cement mortar.
4
Backfill the rings above water table with clay.
Compact it well.
Above the water table, the joints
should be watertight to prevent
surface water from entering the well
(8.16/4;
The joints between the rings should
be smooth from inside.
Clay backfill is an additional
protection to prevent surface water
from entering the well.
8.18 Manufacturing a Well Cover
A well cover is a cover made from concrete to be placed on top of the lining. The purposes,
the types and the manufacturing procedures of a well cover are described in this chapter.
A) Purposes of a Well Cover
A well cover serves the following purposes:
1. It prevents (or reduces) possible pollution of the water in the well.
2. It holds the pump or any other water lifting device.
3. It provides an emergency opening in case of pump break-down.
4. It is removable in case major maintenance or deepening the well becomes necessary.
B) Well Covers for Different Water Lifting Devices
The well covers differ according to the water lifting device to be used.
262
1. Well Covers for a Bucket
Lifting water by bucket and rope is appropriate wherever maintenance of more sophisticated
systems cannot be ensured. In this case, any well cover is already an improvement on wells
without.
These are possible well covers for buckets:
The elevated concrete well cover provides most protection from pollution.
2. Well Cover for a Hand Pump
If a hand pump is to be installed, the well cover must be from reinforced concrete in order to
withstand the movements and vibrations of the hand pump. The hand pump body can be
either cast directly into the cover, or bolts are cast into the cover and the pump is later fixed
with nuts. The former is a very strong, watertight connection, the latter has the advantage that
the pump can easily be replaced by another type. However, if the seal is not intact, the
connection might not be watertight.
3. Well Cover for Electrical Pump
The installation of an electrical submersible pump requires only a cylindrical opening of 10 to
20 cm Ø. The electrical cable and the delivery pipe will enter the well through this opening.
However, the opening must be sealed watertight by a metal sheet or rubber cut to fit exactly
to prevent pollution.
263
Well cover for electrical pump:
C) Emergency Openings on Well Covers
The advantage of a large diameter hand dug well is that the cover is big enough for an
emergency opening. This is to be used whenever the pump breaks down, cannot be repaired
immediately, and people need the water, or when cleaning of the well bottom becomes
necessary. The emergency opening can be constructed in three different ways: a manhole
with metal door, a man hole with concrete lid, or a cover cast in two sections, one of them
being removable.
CROSS-SECTION
LAYOUT PLAN
Having an emergency opening is one of the advantages of a hand dug well over a borehole
and, therefore, it is not at all advisable to build a well cover without an emergency opening.
D) Moulds for Making Well Covers
A well cover should fit properly on the top of the lining. Different moulds can be used:
264
1. Mould from Timber for Well Cover on Top of Brick Lining
A simple mould can be made from timber for an octogonal (= having eight sides) well cover
instead of round shape. Only the corner pieces have to be cut to size. An octogonal cover is
lighter than a square cover.
2. A Hole as Mould for a Round Well Cover
A hole dug into the hard ground can serve as a mould, but only once.
3. Outside Mould for Concrete Rings
The outside mould for rings can be used to manufacture an exactly fitting well cover. This
method, described under E), is not very handy, because the big mould hinders the work, but it
should be used if a special mould for well covers is not available.
4. Special Mould for Well Covers
A special mould for well covers looks exactly like the outside mould for a ring, although the
height is only 15 cm.
265
Manufacturing a Well Cover:
SCALE 1:10
The Finished Well Cover:
E) Casting a Well Cover
Casting a well cover is explained here for an India Mark II hand pump which is cast into the
cover, and has a manhole with metal door. An outside ring mould is used. The other types
can be manufactured in a similar way with minor modifications. The different parts of the pipe
mould are explained in 8.16/7f.
The described well cover with its reinforcement is strong enough to withstand the dynamic
load of a hand pump and will not develop cracks if well made.
Step-by-Step Procedures
266
No
1
Step
Cut a triangle from each of the legs of the
pump body. Bend them into horizontal
position and weld the cut.
Reason
The pump body suitable for boreholes
needs to be adjusted for a hand dug well
cover.
2
Provide the metal door of the man hole with
locking facilities (e.g. iron bar with hinge for
padlock) and anchors (“dastours”). Nail a
wooden frame as shuttering for the man
hole.
A man hole is necessary for cleaning the
well bottom or for drawing water when the
pump is broken. It must be lockable in
order to prevent contamination.
3
Place the base plate of the pipe mould
horizontally and fill it with wet sand up to the
brim.
The base plate needs to lay horizontally
because the position of the pump body
and the slope of the slab need to be
measured from horizontal ground.
Scale 1:15
267
4
Make a ring from reinforcement (8 6 mm
laying 2 cm inside the edge of the base
plate. Cut welded mesh into round shape
slightly smaller than the pipe mould.
5
Place the pump body and the man hole
shuttering and door on the welded mesh in
correct position. One leg of the pump body
must be in direction of the spout. Cut
openings into the welded mesh accordingly.
Cut reinforcement Ø 16 mm and place the
bars under the tip of the legs of the pump
body. Fix additional reinforcement Ø 6 mm
outside the man hole. Fix all reinforcement
with wire.
6
A ring from zinc is placed in the position of
the pump body, the shuttering in the position
of the manhole, and both are filled with sand.
All other parts are taken away. The outside
pipe mould is placed on the base plate. Paint
mould and base plate with old engine oil.
Pour 2 cm concrete (mixture 1:3:4) into the
edge and compact it. The reinforcement rod
Ø 6 mm is placed on top.
268
The reinforcement ring Ø 6 mm shall
reinforce the edge of the cover. The
welded mesh prevents the cover from
bending and breaking.
Scale 1:15
If the different parts are too near to each
other, the legs of the pump will not be
properly embedded in the concrete. The
reinforcement bars Ø 16 mm carry the
pump body and take up the movements.
Scale 1:15
The base plate and the outside mould
ensure that the cover will fit exactly on top
of the last ring. The zinc ring prevents
concrete from pouring through the gap
below the pump body. The shuttering will
provide the manhole opening.
7
Pour concrete 2 cm thick all over the cover
and compact it well. Place welded mesh,
reinforcement bars Ø 16 mm and the pump
body on top. Check the position of the pump
body with the spirit level (in all directions).
Scale 1:15
Concrete 2 cm thick must be underneath
the reinforcement in order to prevent it
from corroding. The pump body’s top
needs to be horizontal so that the riser
main pipes will hang vertically.
8
Pour concrete into the cover and compact it
until the legs are almost covered. Place
small pieces of welded mesh above the tips
of the pump legs. Place the manhole door
with a slight slope outside.
Scale 1:15
Welded mesh above the tips of the pump
legs prevents the surface of the slab from
cracking due to pump movements. The
water should run quickly over the manhole
instead of entering.
Scale 1:15
269
9
Poor concrete up to the brim of the door
frame. It should well cover the pump legs
(the slab will such become 10 to 12 cm
thick). Cover the slab with cement mortar
(mixture 1:4). It should have a slope in all
directions, however, a bigger slope under the
spout. Smooth the surface with the trowel
and sprinkle cement on top with a small
sieve.
10
Write the date into the fresh concrete. Cover
the slab three hours later with wet sand.
Keep it wet for one week.
11
Place the cover on the well only after two
weeks at the earliest.
Install the pump after three weeks at the
earliest.
12
The pump legs needs to be well covered
in order to prevent cracking and corroding.
The slope ensures that rain water and
spilled water runs away quickly. A smooth
finish is slippery and dangerous. A rough
finish is not slippery and strong.
Scale 1:25
Curing the concrete (= keeping it wet)
makes it very strong and prevents cracks.
This is especially necessary because the
cover will be subjected to dynamic load.
Before that the cover is not yet strong
enough. See 6.6/6f.
Dynamic loads must not be exerted earlier
because they are heavier than static
loads. If cracks have once developed,
they will widen through the pump
movement.
8.19 Well Head with Hand Pump
For the users, the well head is the only visible and most important part of a well. It is as
important for the functioning of a well as the parts below. The elements of a good well head
are explained here, both for a borehole and a hand dug well, as they are almost alike. For
other types of water-lifting devices, the well head is basically the same except for the pump
parts.
It is a completely false economy to try to save money by making a smaller platform or by
using a weak cement mixture, or to save time by installing the pump before curing is
complete. Such measures will certainly lead to cracks in the platform, which subsequently
leads to quick pump break-down and pollution of the water. To repair a cracked platform
means having to destroy it completely and to replace it by a new one. This, obviously, is much
more expensive than making a proper platform in the first place. To repair the hand pump
repeatedly without repairing the cracks is a waste of money because cracks allow the pump
body to move and to shake, and the constant unnecessary vibration is bound to wear out the
hand pump parts quickly.
270
How to construct a good well head is described in 8.20.
A) Elements of a well head
A well head with hand pump (or a water point with tap) consists of the following elements,
both for borehole and hand dug well:
No
1
Part of the
Well Head
pump body
Description
Function
Pay Attention at
body with three
legs
to hold the whole
hand pump incl. pipes
and pump head
concrete block
0.80 × 0.80 ×
0.80 m or well
cover
concrete slab
0.10 m thick,
with
elevated
edges
elevated
concrete slab
ditch made of
concrete
dug pit 1.00 x
1.00 x 0.80 m
filled
with
stones/gravel
fence around
the
platform
with door
lock for door or
chain
and
padlock for the
hand pump
to prevent pump from
moving
one leg in the
direction of the
spout,
positioned
level
pump legs well
covered
with
concrete
2
pump
foundation
3
platform
4
6
pumping
stand
drainage
channel
soak-away Pit
7
fencing
8
lock
9
clean
surroundings
not muddy, free
of rubbish and
high grass
a
good
caretaker
duties
behaviour
8.33
5
10
and
see
to prevent dirty water
from entering the well
to give the user a firm
stand
to drain spilled water
far away from the well
to prevent the place
from
becoming
muddy and to prevent
mosquito breeding
to keep animals away
from the well
to control the use of
the pump, to lock
when damaged, to
prevent
further
damage
to prevent containers,
people
and
groundwater
from
getting dirty
to ensure proper use
and implement the
wishes
of
the
community
WS
slight slope towards
drainage channel, a
jerrycan must fit
under spout
located at the end
of the handle
slope
from
the
pump away
at the end of the
drainage channel
WS
can also
hedge
WS
+CD
be
a
WS
WS
WS
dismantling
the
chain daily spoils
the pump
CD
continuous
cleanliness
necessary
CD
is
the caretaker has
technical and social
duties
WS = Water Supply Department; CD = Community Development Department
271
Work
of
WS
CD
+WS
If only one of these elements is missing or not well functioning, there will be problems in the
daily operation of the hand pump.
B) Well Head of a Borehole
LAYOUT PLAN A-A
SCALE 1:50
LAYOUT PLAN B-B
SCALE 1:50
272
C) Well Head of a Hand Dug Well
LAYOUT PLAN A-A
SCALE 1:50
273
LAYOUT PLAN B-B
SCALE 1:50
274
8.20 Completion of a Well
After lowering the rings, the well still needs to be completed. A completed well is shown on
8.19/5f. For completing a well, follow these steps:
Step-by-Step Procedures:
No
1
2
3
Step
After the well has been dug deep enough into
the water and all the rings have been
lowered, check if the rings are horizontal. If
not, dig until the rings are horizontal, or
balance the difference with mortar in the
joints of the rings.
Wash the rings inside and outside if
necessary.
Backfill the rings with gravel in the bottom
and clay in the top. Compact the backfill well
layer by layer. A simple method for backfilling
is described in 8.17/23f. See also 8.19/5.
4
Sieve filter material (sand, fine gravel Ø 3-5
mm, rough gravel Ø 10-15 mm, and stones Ø
20-25 mm) and wash it. Use three sieves
from mesh of different sizes.
5
Clean the bottom of the well from all mud and
organic material and level it. For this work,
dewatering of the well might be necessary.
Pour one layer of sand evenly over it,
afterwards a layer of fine gravel, then a layer
of rough gravel and then a layer of stones. If
the well has a very great yield, place a base
plug on top. A base plug is a round slab with
two handles from filter type concrete (mixture
1:1:4), slightly smaller than the diameter of
the ring.
275
Reasons
The rings need to be horizontal so that
the cover will be placed horizontally as
well.
Mud and rests of old engine oil spoil
the groundwater.
Gravel backfill in the bottom allows the
water to enter the well. Clay backfill in
the top prevents contaminated surface
water from entering the well. Not
properly compacted backfill will settle
later on and cause the platform to
crack.
Organic material in the well spoils the
water.
Rotting organic material spoils the
water quality. For dewatering a well
during construction see 8.25-28. The
filter prevents sand and mud from
entering the well and thus makes the
water clear. A base plug is only
necessary where the inflow is so strong
that it might wash out the sand.
No
Step
Reasons
6
Remove all dirt, like grass, animals, etc. from
the water.
7
Pump the well as much as possible.
8
Place cement mortar on the rim of the top
ring. Lift the well cover by a steel cable
through the pump body and the man hole and
let it slide over strong pipes until it is on top of
the well. Place it on the top ring and adjust it
until the top of the hand pump body is level
into all directions.
9
Carefully smear the space between the top
ring and the cover with cement mortar.
Pour a 10 cm thick layer of gravel around the
well, Ø 3.00 m. It shall have a slight slope
outwards.
Put one ring of reinforcement 0 6 mm around
the top ring at 2 cm distance from it.
10
11
12
Pour concrete (mixture 1:3:4) over the gravel
in a 10 cm thick layer as an apron of 3 to 4 m
diameter. Compact it well. It shall have an
outside slope. The top of the apron must be 2
cm lower than the lowest edge of the well
cover. Build an elevated round edge of
concrete around the apron. Cover the slab
with cement mortar (mixture 1:4) and smooth
the surface with the trowel. Sprinkle cement
on top with a small sieve. All corners shall be
rounded, because sharp edges and corners
are more easily damaged than rounded ones.
276
Scale 1:20
Animals left in the well will die and
decay, also grass and other dirt, and
spoil the water.
Pumping eventually removes still dirty
water and allows clean water to enter
the well.
The well cover seals the well from
contamination and supports the hand
pump. If the top of the hand pump body
is level, the riser main pipes will hang
vertically.
The well must be properly sealed
against dirty water and animals.
The gravel is the foundation for the well
apron.
The reinforcement shall prevent cracks
in the immediate neighbourhood of the
well cover.
The apron prevents spilled water from
entering the ground and polluting the
well. Also it prevents the surroundings
of the well from becoming muddy. Thus
the water containers will remain
cleaner. The elevated edge helps
collect spilled water and direct it to the
drainage channel.
It is easily possible to remove the well
cover at any time because the apron is
not connected to it.
No
Step
13
Construct a drainage channel with slightly
elevated round edges and sufficient slope
(e.g. 1:10) in front of the spout. Dig a soakaway pit, 1 m deep, at the end of the
drainage and fill it with stone layers in the
opposite way as the filter (see 8.19/6).
Cover the apron and drainage channel 3
hours after construction with wet sand. Keep
them wet for one week.
Fence the area around the well (at least an
area of 10 m × 10 m) and construct a door.
Alternatively, you can plant a hedge. Clean
the well compound properly.
14
15
Reasons
16
Install the hand pump. See 8.31.
17
Disinfect the well. See 8.36
18
Conduct the operating instruction for the
whole community where the importance of
water, proper use, running and maintenance
are discussed. See 8.39.
Scale 1:20
The drainage channel transports spilled
water far enough away from the well to
prevent contamination. The spilled
water can also be used for gardening
or watering animals.
Curing the concrete (= keeping it wet)
makes it very strong and prevents
cracks.
A fence prevents animals from polluting
the area around the well and it makes
the well easier to be controlled. The
fence must be built before hand pump
installation.
Pulling water by a hand pump from a
hand dug well prevents pollution of the
water.
The well has been contaminated during
construction. This needs to be
eliminated before handing the well over
to the community.
As water supply is a technical and
social issue, community structures
need to be built beside the construction
8.21 Safety Measures
Well construction is a dangerous work. We need to take great care to prevent risks as much
as possible. Therefore, keep strictly to the following safety measures.
A) Safety through Stability of the Well
No
1
Safety Measure
Watch the walls of the well constantly.
2
3
Make dry sand in the well wet before digging.
Below water table, always work in the
protection of a ring.
Never step on the very edge of a well without
collar.
4
5
Dig drainage channels around the well head
and cover the well with zinc sheets over
nigths.
277
Reasons
Slight changes in the appearance may suggest
collapse.
Wet sand is more stable than dry sand.
The soil below the water table is always much
more unstable than above.
You could loosen a part of the soil and induce
partial collapsing, endangering yourself and
somebody working down in the well.
Rain water entering the well increases the
danger of collapsing.
B) Safety through Good Equipment and Cleanliness
No
1
2
Safety Measure
Check all equipment daily, like buckets,
ropes, knots, pulleys, scaffold. Replace
them if they show signs of old age or
damage.
Inspect tripod and winch before using
them. Brake and safety device must work
(see 8.17/17f).
Reasons
First signs of damage can easily develop
into major breaks when under load. The
scaffold must be very stable and well
embedded into the ground soil.
Sudden release of load causes the winch
handles to turn with terrible speed and can
cause bad injuries. Failure of the tripod can
cause bad injuries or kill somebody, too.
The pulley can get untied under load.
Small items can fall accidentally into the
well and harm the diggers.
3
4
Tie the pulleys properly to the scaffold.
Keep the area around the well free from
gravel, stones and unnecessary tools.
Clean each day.
No
1
Safety Measure
Always wear a safety helmet when
entering the well.
Enter a well on a sitting wood, a bosun’s
chair, or over a ladder. Sit properly on the
sitting wood.
Reasons
The helmet prevents small particles falling
down from damaging your head.
Other methods of entering are unsafe
because you can easily slip.
Check the bottom of the well with a stick
for snakes before you enter the water.
Keep the surroundings of the well free
from vegetation. When meeting a snake,
do not panic, but move slowly.
Sometimes there are snakes in the well.
2
3
278
No
4
Safety Measure
Pull the rope evenly with enough people.
Avoid bumping against the walls.
5
Tie shovels, crowbars, etc. properly when
lowering them with a bucket according to
the drawing.
6
Do not overload buckets. Use buckets
reinforced with flat iron.
Never urinate or defaecate inside the well,
but exit the well for these purposes.
Do not let your fingers enter the pulley
when being pulled up.
7
8
279
Reasons
Abrupt pulling can cause swinging of the
bucket and puts a bigger load on the rope.
Enough people prevent accidents if one of
them fails during pulling. Buckets bumping
against the wall can cause collapse and
result in spilling the contents.
Otherwise heavy tools can make the
bucket tip over.
Overloaded buckets can tilt easily and the
rope wears out quicker.
Excreta will contaminate the water of the
well.
The pulley can hurt your hand badly.
No
9
10
11
Safety Measure
If you get wet during work in the well,
immediately take off the wet clothes after
leaving the well and put on dry ones. Take
an extra set of clothes with you for this
purpose. Drink enough water. Women
should take special care.
Keep the danger of bad air in mind.
Use the safety belt in any dangerous
situation like bad air, work under water,
etc.
Reasons
Wet clothes on the body, especially if
exposed to wind or draft, can cause
sicknesses of the kidneys, urinary tract
and female reproductive organs. The bad
effects are not felt immediately, only later.
See 8.22
See 8.22
D) Safety through Good Communication
No
1
2
3
4
Safety Measure
Solve any quarrels between labourers
before continuing work.
Somebody at the well head must be
assigned to constantly watch the. diggers
down, to communicate between diggers
and labourers above, and to direct the
work.
Use clear signals according to the
drawing:
Reasons
Unsettled quarrels make people careless
and inattentive and cause danger.
The diggers at the bottom are helpless in
the face of problems unless somebody
can hear them.
Keep passers-by and children away from
the well (if necessary by an improvised
fence).
Curious people want to watch, but do not
know the dangers. They can endanger
themselves and the workers
Clear signals, known to
prevent misunderstanding.
everybody,
8.22 Ventilation in Wells
Air is the first priority physical need of any human being. Without air human beings suffocate
and die within a few minutes. Therefore, it is most important to take care that the workers
down a well have a sufficient supply of air. There are cases where several people have died
in a well because of bad air.
A) Possible Reasons for Bad Air Conditions in a Well
The following reasons can cause bad air conditions in a well:
280
1. The ground soil releases dangerous gases (suffocating, explosive or poisonous gases).
2. The well is very deep and narrow and the natural ventilation is not sufficient.
3. The well dried out and no natural ventilation through evaporation takes place.
4. The workers stayed long time down in a deep well and, thus, consumed the oxygen and
increased the carbon dioxide content by exhalation.
5. Fumes from the exhaust pipe of a generator, car or pump descend into a well.
6. The well is closed by a cover and has only a small man hole.
7. Something was burnt in a well.
8. Rotting organic material can cause dangerous gases.
Be very careful in any of these cases!
B) Methods to Check the Air Conditions in a Well
1. Check the air with the candle test. Fix a candle in a bucket, light it and gently let it down
the well shaft. If the candle burns until the bottom, the air conditions can be expected to be
reasonable. The air is bad if the candle extinguishes. Carry out the candle test before
starting work on the site in any well deeper than 10 m. Carry out this test daily in any well
deeper than 30 m.
2. Check the air for bad, foul smell (but not all kinds of bad air have a bad smell!).
3. Check the air with specialized instruments. These might not be available.
Use any of the methods available at the site.
C) Possibilities to Improve the Air in a Well
To improve the air in a well, you may use one or more of the following methods:
1. Use an airblower with a hose, pumping fresh air into the well. The hose shall reach until
1-2 m above the workers to avoid catching a cold.
2. Use a small compressor with hose to blow air into the well. The hose shall end high
above the workers.
3. Use a blacksmith’s fan with a hose.
4. Sprinkle water into the well.
5. Raise and lower a basket or a bundle of twigs quickly and several times.
6. Make sure that the well has always a bit of water.
Use the method(s) available and appropriate and check the air afterwards again. Repeat if
necessary.
D) Other Precaution Measures
1. In case of any doubt about the air conditions, tie the worker entering the well to the
rope. Even if she/he falls unconscious, she/he can be pulled out before serious damage.
Do not fear people laughing about such precautions, because you are just protecting your
live. You can tie somebody with ordinary rope or use a safety belt.
281
How to Tie the Rope:
How to Wear the Rope
How to Wear the Safety Belt
282
2. Somebody at the well mouth has to watch the workers at the bottom constantly and
carefully.
3. Allow workers to work only for short periods (1 to 2 hours, maximal 3 hours) down in the
well. Exchange them afterwards.
4. Place a generator, car or another machine as far from the well as possible, preferably
downhill. The exhaust pipe should point away from the well. Exhaust fumes are heavy and,
therefore, easily descend into a well.
5. For respiratory emergency see 1.7/3.
8.23 Ropes and Knots
A rope can transmit tension, but not compression. In other words, you can pull with a rope,
but never push. Ropes are flexible and can be wound up for storage.
A) Types of Ropes
Three different kinds of ropes can be used in well construction:
No
Type of
Rope
Usual
Ø for
well
constr.
10
mm
1
steel
rope or
steel
cable
2
nylon
rope
10
mm
3
manila or
hemp or
sisal
rope
25
mm
Pulled by
Strength
Protection
of Rope
End
winch,
difficult to
pull
by
hand
very
strong
welding
(gas
welding)
or
braiding
by hand,
however,
it gets hot
and
is
slippery
and
difficult to
hold
by hand,
does not
get hot
strong
burning
(melting)
and knot
strong
tying with
string and
knot
Maintenance
Used for
- always roll
the
cable
properly
- prevent it
from
remaining wet
- inspect it
regularly
- carefully roll
it
- inspect it
regularly
heavy loads
like rings in
permanent
installation
- let it dry if it
gets wet
- carefully roll
it
- inspect it
regularly
lowering and
lifting people
and buckets
into the well
any
quick
work
in
between
Handle ropes according to these guidelines:
- New ropes tend to twist when first loaded. Pay attention!
- Provide the ends of ropes with some protection before you start to use them. The rope
looses strength when untwisted.
- The strength of ropes is reduced by about half when they get old.
283
- Avoid friction between rope and pulley or any other item.
- Check the ropes every morning for weak spots.
- If one of the three fibres of a rope is broken at one spot only, the rope must not be used
any more for heavy loads.
- Store rope in a dry, airy place, rolled up or in a box and protected from rats.
- Steel cable is a special kind of rope. How to handle it is explained in detail in 8.17/16.
B) Types of Knots
Nylon and sisal ropes are connected with knots. Use the following kinds of knots which are
quick to make, safe to use, and easy to untie. Practice them until you know them by heart.
1. Bowline
for tying buckets, etc.
2. Square Knot
for connecting ropes
Steel cable cannot be connected with knots. The ends of steel cable have to be provided with
eyes; the eyes are then connected with D-shackles or connecting links. For details see
8.17/16.
8.24 Types of Pumps and Other Water Lifting Devices
This chapter gives a rough overview about the diversity of pumps and other water lifting
devices.
A pump is a device capable of transporting a fluid (or gas) by using energy supplied from
outside.
284
A) Distinction of Water Lifting Devices and Pumps
Pumps and other water lifting devices can be distinguished according to
1. source of energy used,
2. principle of transporting the fluid,
3. type of fluid transported,
4. maximum lift.
Examples (see 8.24/6ff)
No. 1 to 14, 16, 17, 18, 19, 22;
donkeys pulling water from a well
solar pump
No. 15;
No. 21, 26;
No. 30, 31;
diesel and petrol pumps such as No. 20, 23,
24, 25, 27, 28, 29, 32;
1. Source of Energy Used
- human power
- animal power
- solar energy
- wind energy
- water energy
- electrical energy
- fossil fuel energy (combustion engine)
2. Principle of Transporting the Fluid
- bucket
- continuous rope and bucket system
- piston pump (positive displacement)
- membrane pump (positive displacement)
- centrifugal pump
- impulse pump
- ejector pump
- helical rotor pump
- coil pump
- rotary pump
No. 1 to 5;
No. 6 to 8;
No. 9 to 15, 18, 28;
No. 16, 17, 19, 20; blacksmith’s belly;
No. 29 to 31; airblower; “fan”;
No. 21;
No. 32;
No. 22 to 24;
No. 26;
No. 25, 27;
3. Type of Fluid Transported
- clear, clean water
- dirty water
- mud
- fuel or oil
- air
No. 1 to 32;
No. 1 to 8, 16, 17, 19 to 26, 29, 30;
No. 24 and special pumps;
fuel or oil pump in the car;
airblower;
4. Maximum Lift (=Head)
The head is the vertical distance between the intake level and the discharge level:
- shallow well pump = suction pump
(head: 0 to 7 m)
- deep well pump = lift pump
(head: 0 to 7 m and deeper)
No. 2, 9, 19, 20, 24, 25, 26,29;
No. 1, 3 to 8,10 to 18, 21, 22, 23, 27,
28, 30, 31, 32;
285
B) Work of a Pump
A pump has to overcome
- the gravitational forces of the water,
- the friction in the pump and the pipes,
- the inertia of the moving parts of the pump.
C) Possible Reasons for Poor Performance of a Pump
There are many different reasons why a pump is not performing well in a certain situation. It is
important to identify the exact reason.
Possible reasons are listed below:
- The pump is of poor quality.
- The pump is of poor design.
- The pump is not suitable for the given situation.
- The pump does not work in its optimal range (e.g., the head is too high after the water
table has dropped).
- The pump is not being used properly.
- The pump is not maintained regularly (cleaning, greasing, etc.).
- The pump is unduly exposed to sun, rain, dust, etc.
- The pump is overused.
- The pump was not repaired properly after a break-down.
- Supply of spare parts is difficult because there are too many different types of pumps in
the region.
D) Criteria for Selecting the Right Pump
To avoid poor performance, it is important to select the right type of pump for a specific task.
The following questions will help you to identify the specifications for the pump you need for a
specific purpose. First, answer them all, then check if the proposed pump fulfils these
requirements.
1. Which head do you want to pump the water (in metres)?
2. What yield do you require (in m3/h or l/sec)?
3. What type of water should be pumped (clear, sandy or muddy water)?
4. What source should the water be pumped from (hand dug well, borehole, river)?
5. For how long should water be pumped subsequently: How many hours a day; the whole
day; sometimes; daily; for how many months?
6. What kind of energy is available and should run the pump (human, animal, diesel,
petrol, electricity, etc.)?
7. What kind of spare parts are available and where?
286
8. What kind of maintenance facilities are necessary and available?
9. What kind of operating skills are necessary and available?
10. Do you require that the pump ensures that the water is not polluted?
11. What level of technology is suitable?
12. Where can you get the required pump from?
13. What kind of pump would be accepted by the future users?
14. How much money are you able and ready to invest in the pump (including running and
maintenance costs)?
E) Comparison of Different Pumps
In the following table a number of pumps are compared. The necessary information is
compiled to answer the questions asked under “D) Criteria for Selecting the Right Pump”. The
drawings under F illustrate the different pumps.
287
COMPARISON OF DIFFERENT PUMPS
Pump
Drawing Source
No.
of
Energy
unprotected
1, 5
bucket system
shaduf
2
protected
3, 4
bucket system
chain,
rope 6, 7, 8
and
washer
pump, bucket
pump
suction hand 9
pump
with
piston
suction hand 9
pump
for
irrigation with
piston
direct
action 10
hand pump
Lift from Lift from Yield in
Well Ø Possibility of
Costs
Water to Pump to m3/hour required Contamination
Pump
Higher
Level
human, pulling
by clean or 0-50 m
0.05-1
large Ø yes
low
animal rope
dirty water
(100 cm)
human pulling
by clean or 0-5 m
“
“
“
“
counterweight dirty water
“
pulling
rope
Type of
Fluid
by clean
water
“
0-10 m
-
“
0-10 m
-
2-3
0-7 m
-
2
“
“
“
piston, pos.
displacement
“
“
clean or 0-7 m
dirty water
-
8
“
“
clean
water
0-25 m
-
2
“
“
0-80 m
piston
hand 11, 12,
“
pump
13, 14
diaphragm
19
human
hand pump
hydraulic ram 21
Principle of
Fluid
Transport
water
“
membrane
clean or 0-7 m
dirty water
impulse
clean
water
0
only
14
No 1
-
60-80 m
288
10
“
borehole
or large
diameter
large Ø yes
(100 cm)
Suitable
Areas
very simple remote areas
“
“
with
simple
maintenance
facilities
“
“
reasonable
“
“
“
“
avoidable
“
Operation
and
Maintenance
borehole avoidable
or large
diameter
“
“
large Ø yes
(100 cm)
depending not used avoidable
on ram
in wells
“
simple
reasonable where
maintenance
secured
“
“
“
“
“
“
“
“
reasonable simple
“
“
where
maintenance
secured
in small river
with dam
Pump
helical
pump
Drawing Source
No.
of
Energy
rotor 22, 23
human, helical rotor
fuel
coil pump
26
water
centrifugal
pump
29
fuel
submersible
pump
jet pump
30, 31
electrical
32
Principle of
Fluid
Transport
“
Type of
Fluid
water
Lift from Lift from Yield in
Well Ø Possibility of
Costs
Water to Pump to m3/hour required Contamination
Pump
Higher
Level
0-30 m
depending large Ø or avoidable
high
on pump boreholes
compression clean or 0
of air
dirty water
centrifugal
depending 0-7 m
on pump
“
centrifugal,
ejector
“
clean
water
6-7 m
20-30 m
8-300 m
“
0-50 m
0-20 m
“
289
“
“
“
“
“
“
“
not used yes
in wells
high,
borehole avoidable
depending or large
on pump diameter
“
borehole
skilled
attention
Suitable
Areas
where
fuel
and
maintenance
available
on big rivers
(for irrigation)
where
fuel
and
maintenance
available
“
1-2
0
Operation
and
Maintenance
reasonable simple
high
skilled
attention
F) Drawings of Different Pump Types
In the following, drawings are given of a number of pumps, compiled as teaching material.
They shall give an impression about the diversity of pump types. Some of them will need
further explanation by a teacher or further study in the literature (see in the bibliography
especially No. 18 from which many pictures were taken). A few pump types are described in
more detail in later chapters.
Illustrations are given for the following pumps and water lifting devices:
1. Unprotected Bucket System
2. Counterweighted Bailer (=Shaduf)
3. Protected Bucket System with Trough
4. Protected Bucket System with Hose
5. Bailer for Boreholes
6. Bucket Pump
7. Chain and Washer Pump
8. Rope and Washer Pump
9. Suction Hand Pump with Piston
10. Direct Action Hand Pump with Cylinder
11. Piston Hand Pump with Chain Link
12. Piston Hand Pump with Uganda Type Handle
13. Piston Hand Pump with Fly-Wheel
14. Force Pump
15. Wind Pump
16. Vergnet or Mengin Pump
17. Petro Pump
18. Blair Pump
19. Diaphragm Hand Pump
20. Diaphragm Engine Pump
21. Hydraulic Ram
22. Helical Rotor Hand Pump
23. Helical Rotor Engine Pump
24. Archimedean Water Screw
25. Water Wheel
26. Coil Pump
27. Rotary Pump
28. Piston Engine Pump
29. Centrifugal Pump
30. Submersible Pump for Dirty Water
31. Submersible Pump for Clean Water
32. Jet Pump
1. Unprotected Bucket System
rope and bucket alone, or with wooden roller, or pulley, or windlass.
Rope and Bucket alone:
290
Wooden Rollers:
291
Pulley:
Windlass:
292
SCALE 1:80
2. Counterweighted Bailer (= Shaduf)
with scaffold, counterbalance weigh, rope and bucket.
293
3. Protected Bucket System with Trough
with windlass, rope, bucket, trough, outlet, and protection against contamination.
4. Protected Bucket System with Hose
with windlass, rope, bucket, hose, outlet and protection against contamination.
Schematic Illustration
294
5. Bailer for Boreholes with windlass, chain, bailer and holder to release the valve; see also
8.13/5.
295
6. Bucket Pump with windlass, buckets attached to rope, outlet and protection against
contamination.
296
7. Chain and Washer Pump with windlass, riser main pipe, rubber washers, water tank, outlet,
and protection against contamination.
297
8. Rope and Washer Pump with windlass, riser main pipe, rope and rubber washers, basin
from chicken wire and cement mortar, outlet, and protection against contamination.
298
9. Suction Hand Pump with Piston with riser main pipe, two valves in the pump body, plunger,
outlet, and handle; with all moving parts above ground; for wells up to 7 m.
Schematic Illustration
299
10. Direct Action Hand Pump with Cylinder with riser main pipe, rod, and handle directly
connected to the rod; for wells up to 30 m.
Schematic Illustration
300
11. Piston Hand Pump with Chain Link (India Mark II) with cylinder, riser main pipe, rod, water
tank, outlet, chain link, and handle; for deep wells; see also 8.19, 8.31, 8.33.
301
12. Piston Hand Pump with Uganda Type Handle with cylinder, riser main pipe, rod, outlet,
and wooden handle; for deep wells.
13. Piston Hand Pump with Fly-Wheel with cylinder, riser main pipe, rod, outlet, fly-wheel
moving the rod by rotary crank (transmitting the rotation of the fly-wheel into up-and-down
movement of the rod); for deep wells.
Crank Mechanism:
302
303
14. Force Pump either suction type (like No. 9) or with cylinder (like No. 11) for pumping water
from a well to an elevated tank.
15. Wind Pump with cylinder, riser main pipe, rod, connection to water tank, and wind-wheel
moving the rod by rotary crank; for deep wells.
304
16. Vergnet or Mengin Pump with pilot cylinder, pilot pipe, rigid cylinder (with three valves),
discharge pipe and outlet, foot-operated.
305
17. Petro Pump with counterweight holding the lower end of pump in position, a pumping
hose from flexible membrane creating the suction, two valves, riser main pipe moving up and
down, outlet moving up and down, and handle.
Schematic Illustration
306
18. Blair Pump with stationary cylinder, foot valve, riser main pipe which is at the same time
pump rod and plunger with a valve, with bent end of riser main pipe as outlet, and handles.
Schematic Illustration
307
19. Diaphragm Hand Pump with foot valve (= suction sustainer), suction hose, pump body
with two valves, rubber membrane (= diaphragm), handle, outlet; for wells up to 7 m; see also
8.26 for operation.
ISOMETRIC VIEW
CROSS-SECTION (not in operation)
308
20. Diaphragm Engine Pump with foot valve, suction hose, pump body, membrane moved by
engine; for wells up to 7 m.
21. Hydraulic Ram with water storage higher than the ram, supply pipe (= drive pipe), check
valve, air chamber, discharge pipe (= delivery pipe), return spring, waste valve, outlet for
waste water; requires a constant flow from the storage and pumps a small part of this flow to
a higher level.
309
22. Helical Rotor Pump, Hand-Operated with check valve, helical rotor in a fixed stator, riser
main pipe, drive shaft (= rod transmitting the rotation from the pump head to the helical rotor),
outlet, gears (transmitting the rotation of the handles into rotation of the drive shaft), gear box
and handles; for deep wells.
Taken from leaflet, Mono Pump
310
23. Helical Rotor Pump, Engine-Driven with helical rotor in a fixed stator, riser main pipe,
gears, gear box, engine; for deep wells.
24. Archimedean Water Screw with an inclined rotor rotating in a fitting bed (in the shape of a
half cylinder), engine driven; for water or mud
311
25. Water Wheel with a rotating water wheel lifting the water; engine driven; for low lifts.
26. Coil Pump with plastic pipes coiled around a frame work rotating by the action of the river
current on paddles; pump floating on drums; delivery hose to elevated tank; for small lifts from
a river.
312
27. Rotary Pump with rotors within a fixed casing (= stator).
CROSS-SECTION
28. Piston Pump with a piston moved by an engine to create suction for pumping.
CROSS-SECTION in two stages of operation
29. Centrifugal Pump installed on ground level; with rotating impeller within a casing, suction
pipe and delivery pipe; for suction heads up to 7 m and delivery heads up to 30 m; see also
8.27
CROSS-SECTION
313
30. Submersible Pump for Dirty Water with electrical motor and pump within a pump body
submersed into the water, with power supply supplied by electrical cable, and a delivery hose;
for deep wells; see also 8.28.
31. Submersible Pump for Clean Water used in boreholes; with slim shape especially
designed for boreholes; for clean and not salty water and deep wells.
Taken from leaflet, Homa Pump
314
32. Jet Pump with centrifugal pump installed on ground level, pressure pipe, jet body with jet
nozzle, mixing chamber, return pipe, delivery pipe, and elevated tank; pumps water into the
well through pressure pipe, the flow speed is increased by the nozzle and, thus, water sucked
in from the well; the water moves up through the larger diameter return pipe to the pump; a
part is delivered to the tank, the other part is pumped again into the pressure pipe, etc.; no
moving parts in the well
CUT-AWAY SIDE-VIEW
Schematic Illustration
Taken from leaflet, Jet Pump
315
8.25. Dewatering Wells during Construction
When digging below the water table, dewatering of the well becomes necessary in order to
enable the technicians to continue the work. Dewatering can be done by the following
different means. Concerning the yields of different pumps see 8.34 or 8.24/4f.
A) Dewatering with a Bucket, Rope and Pulley
Small amounts of water can be extracted with the bucket used for excavating the soil.
B) Dewatering with Jerrycan, Rope and Pulley
A jerrycan, cut open at its top, pulls in one go twice as much as a bucket, and is light-weight.
Therefore, it is quite suitable for dewatering wells during construction by hand. However,
many people are required. They have to work in shifts. Two jerrycans can be used parallel on
two pulleys.
C) Dewatering with a Large Bucket, Steel Cable, Pulley and Winch
A large bucket, both for dewatering and lifting excavated soil, can be manufactured locally
from a metal drum. Cut off one third of the drum and reinforce it with three rings of flat iron. A
reinforcement rod Ø 10 mm must go all around the bucket to bear the weight and to serve as
a handle.
Such a large bucket can be filled half way with soil, or completely with water. It is to be pulled
by steel cable and winch. The method empties a well quickly, but requires a number of people
to work in shifts as the work is very heavy.
D) Dewatering with Hand-Operated Diaphragm Pump
The method is described in detail in 8.26. It can be used only for wells up to 8 m deep,
because a diaphragm pump is a suction pump. It requires heavy manual labour, but no fuel,
few spareparts and little skill. If the yield of the well is not extremely high, this is a very good
method for dewatering a well.
316
E) Dewatering with a Fuel Powered Suction Pump
The method is described in detail in 8.27. It can be used only for wells up to 8 m deep. It
requires fuel, spare parts and skilled labour. The method is appropriate if the yield of the well
is very high.
F) Dewatering with Submersible Pump
The method is described in detail in 8.28. It can be used for deep wells, too, depending on the
pump selected. It requires a transportable generator, fuel, spare parts, and skilled labour. The
yield is normally less than for fuel powered suction pumps. The method is suitable if
dewatering by hand becomes too tiresome, especially in deep wells.
G) Selecting the Suitable Dewatering Method
The method suitable for a particular well has to be selected according to the available
manpower and equipment. Sometimes, two or three of the above methods can be used at the
same time (= in parallel = simultaneously) or one after another (= consecutively).
Often, the dewatering facilities determine how deep a well can be dug into the water table. If
the water returns into the well more quickly than you can dewater it with the available
facilities, digging cannot be continued any more.
It is very important to dig as deep into the water table as possible in order to have some
reserve for dry years. With careful planning you can reach the maximum depth possible with
the given facilities:
1. Plan the work so that you combine all available people and dewatering facilities. Work
overtime for a short period until digging and lining below the water table are finished.
An example for bad planning would be: You start dewatering on Friday morning. Up to
14.30, the end of the working hours, you have just managed to empty the well and the
actual work could start. During Saturday and Sunday, the well fills up again. On Monday,
you again dewater until 14.30, and stop work. On Tuesday, you dewater until 13.30 and
dig for one hour. On Wednesday, you dewater until 13.30 and dig for one hour... - with
completely demoralized staff.
2. Keep careful record of all your activities including the time, water table, number of
pumps, buckets, etc. used. Keep track of how quickly the water returns into the well over
night (how many cm per hour).
3. Plan the work so that digging into the water table will take place at the end of the dry
season when the water table is at its lowest.
8.26. Diaphragm Pumps
Diaphragm pumps suck up the water through up-and-down movement of a flexible rubber
membrane called a diaphragm.
A) Types of Diaphragm Pumps
Diaphragm pumps can be differentiated according to the type of energy which drives them:
1. Engine driven diaphragm pumps pump very high yields and are not discussed here.
2. Hand operated diaphragm pumps are designed for irrigation purposes in order to lift a
big amount of water with a small head. This type of pump is also very suitable for
dewatering shallow wells during construction and will be discussed in the following.
317
B) Range of Use
Being a suction pump, the possible lift of a diaphragm pump is limited to 8 m.
C) Elements of a Pumping System with a Diaphragm Pump
A pumping system with a diaphragm pump consists of the following elements:
D) Description of the Diaphragm Pump
A diaphragm pump consists of a metal body holding the flexible rubber membrane, the
diaphragm. The membrane has a round opening in the middle, reinforced with a steel ring.
The ring is connected to the handle and also holds the upper valve. The bottom valve, made
of a rubber ball, is placed at the inlet of the suction pipe.
The operation of a diaphragm pump has two distinct and alternative phases:
1. Phase
- The handle moves downwards.
- The membrane moves upwards.
- The upper valve closes by its weight.
- The membrane creates suction and opens the bottom valve.
- Water is sucked in through the suction pipe.
318
Schematic Illustration Diaphragm assembly turned by 90° for clarity; see also 8.24/22.
2. Phase
- The handle moves upwards.
- The membrane moves downwards.
- The backflow of water closes the bottom valve.
- The water wants to escape and opens the top valve.
- The water is delivered in an open outlet.
- The water in the suction hose does not move.
The two valves open and close alternately and, thus, the water is lifted in steps (not
continuously). The foot valve at the bottom of the suction hose (the third valve!) is
indispensable. It allows the water to be primed, i.e. to be gradually lifted until the hose is full.
The foot valve also makes it possible to rest during pumping without having to prime all over
again.
E) Advantages and Disadvantages
The advantages of a hand operated diaphragm pump are:
319
- It is very simple.
- It is sturdy (= strong, not easily damaged).
- Its operation is very simple.
- It does not require fuel.
- The yield is high.
- It can pump sandy water because there are no sensitive parts which can wear out
quickly.
The disadvantages are:
- The pump can only pump up to 8 m depth.
- Pumping is hard work and requires enough people to work in shifts.
- The suction hose can wear out quickly.
- The membrane needs to be replaced from time to time.
F) Operation of a Diaphragm Pump
The operation of a diaphragm pump is extremely simple:
- Assemble pump, suction hose and foot valve.
- Pump.
However, take care of the following points:
- The pump must be fixed on a board of 2 pieces of timber 2” × 8”, 2 m long. The board
must stand on level and stable ground and should not move.
- Handle the suction hose with great care to avoid damage. Do not pull it over the rough
edge of the well. The suction hose must be airtight (without the slightest hole), otherwise,
the pump cannot suck.
- Tighten all bolts firmly.
- Two or three people can pump, but they should move the handle from the highest
possible to the lowest possible position in an even rhythm. They should not jump with the
handle.
- After work, do not leave the membrane exposed to sun, but cover it. This prolongs its
lifetime.
8.27 Fuel-Powered Suction Pumps
The most common type of fuel-powered suction pump is a centrifugal pump with suction and
discharge hose or pipe.
A) Types of Fuel-Powered Suction Pumps (Centrifugal Pumps)
Suction pumps can use diesel or petrol as fuel:
1. Diesel powered suction pumps are heavier and, therefore, more suitable for permanent
installation. They will not be discussed here.
2. Petrol powered suction pumps are usually light-weight and, therefore, transportable and
320
very suitable for dewatering wells during construction. They will be discussed in the
following with the HONDA WA 30 X as an example.
B) Range of Use
Fuel powered suction pumps are, like all suction pumps, limited to a depth of 8 m.
C) Elements of a Pumping System with a Petrol Suction Pump
A pumping system with a petrol powered suction pump consists of the following elements:
D) Description and Specifications
A petrol engine produces rotational movement and directly turns the axle of the attached
centrifugal pump. The rotating blades suck water through the suction hose and press it
through the discharge hose to a higher level. As the energy of the fuel is directly converted
into mechanical energy which turns the pump, there are small losses and the pump has a
high efficiency.
The pump is started mechanically by a recoil starter. A foot valve (= suction sustainer) at the
bottom of the suction hose makes priming much easier. The centrifugal pump is cooled by the
water pumped and, therefore, must never run dry.
The specifications and the performance curve of the HONDA WA 30 X pump are given here
as an example:
pump type
suction hose
discharge hose
suction head
discharge head
total head
Specifications
centrifugal, self priming
Ø 3”
Ø 3”
8m
20 m
28 m
321
Remarks
a suction sustainer helps
priming
max. capacity(yield)
direction of rotation
displacement
1100 l /min = 66 m3/h
counter clockwise
144 cm3
engine
maximal output
4 stroke overhead valve, air cooled
single cylinder
5.0 HP
fuel tank capacity
fuel
fuel consumption
aircleaner
starting system
cooling system
dimensions
dry weight
3,600 rpm
3.6 l
petrol
230 g/HPh -> 1,150 g/h =1.5 l /h
semidry
recoil starter
forced air
620 × 410 × 485 mm
35 kg
self
priming
time
continuous running time
120 sec at 5 m head
= the volume displaced
by the piston in a single
stroke
= horse power (Engl.)
= PS (German)
= revolutions per minute
battery starter is heavier
easily
transportable;
diesel
engines
are
heavier
after that the engine runs
too hot, therefore stop.
2 h 40 min
Performance Curve
Example:
Water is to be pumped from a well 5 m deep and discharged into a container 7 m above
ground level.
Total Head
=
=
Suction Head
5m
+
+
Discharge Head
7m
=12 m
According to the curve, the yield is to be expected about 820 l /min or 49 m3/h (for
transformation see 8.34/1).
E) Advantages and Disadvantages
The advantages of a petrol suction pump are:
322
- The pump is light-weight and easily transportable.
- Only a hose is lowered into the well which leaves enough space for the technicians in the
well.
- Technicians can work in the well during pumping.
- The pump is able to pump dirty, sandy and muddy water.
- The pump has a high yield.
The disadvantages are:
- The pump can only pump up to 8 m depth.
- The pump needs fuel.
- The equipment is relatively sophisticated and can break down easily.
- Spare parts are difficult to get.
- The pump requires great care during operation.
- The hoses wear out quickly.
F) Step-by-Step Procedures for Operating the Pump
For dewatering a well with a petrol suction pump, follow these steps:
No
1
Step
Place the pump near the well in the shade on a
level surface. The exhaust pipe must direct away
from the well.
2
Connect foot valve, suction hose, pump and
discharge hose. If you have no foot valve, use a
strainer. Place the suction hose into the well, and
the discharge hose far away. The strainer should
be well submersed, but not stand on the ground.
Check engine oil level.
3
4
5
6
Check the fuel level. Do not spill fuel when
refilling.
Check the air cleaner element.
Pour water into the priming water filler plug.
7
8
Turn the fuel valve “ON”.
Close the choke lever (only in cool climate).
9
10
11
Turn the engine switch to the “ON” position.
Move the throttle lever slightly to the left.
Pull the starter grip lightly until resistance is felt,
then pull briskly. Return it gently to the starter.
As the engine gradually warms up, gradually
open the choke.
Set the throttle lever at the desired speed.
Watch if the pump is operating properly and
yielding water.
Stop the pump immediately when it runs dry.
12
13
14
15
323
Reasons
Otherwise the pump easily gets
overheated. On a sloping area the
fuel will spill. Exhaust fumes are
poisonous and heavy and can
easily descend into the well(8.22/lff)
Gravel sucked into the pump will
cause serious impeller damage.
Running
the
engine
without
sufficient oil can cause serious
damage.
Spilled fuel might ignite.
Clean, if necessary.
Otherwise the pump will overheat.
Extended dry operation will destroy
the pump seal.
The choke is not to be used if the
engine is warm or the surrounding
temperature high.
Continuous watching is necessary
to avoid running dry.
Otherwise the pump will overheat
and break down.
No
16
17
18
19
20
21
Step
Move the throttle lever fully to the right (i.e. close
it).
Turn the engine switch to the “OFF” position.
Turn the fuel valve “OFF”.
After pumping muddy, sandy or salty water,
always pump clean water through the pump
before storing.
Do not allow the pump to run continuously longer
than 2 to 3 hours.
Store the pump in a dry, clean place in the shade.
Reasons
To stop the engine in emergency,
just turn the engine switch to the
“OFF” position
Sediments settling in the pump
spoil the impeller.
After 2 to 3 hours, the pump needs
to cool down, because it has no
cooling system with ventilator.
Sun overheats the pump. Rain
causes corrosion.
8.28. Submersible Pumps
A submersible pump is a unit consisting of an electrical engine and a centrifugal pump
submersed into the water to be pumped.
A) Types of Submersible Pumps
Submersible pumps can be differentiated according to their size, from tiny ones to huge
models requiring a very strong power supply. They can also be differentiated according to the
type of water they pump. In wells they can serve two purposes:
1. Permanent installation for pumping clean drinking water after the construction is
completed (often used for boreholes).
2. Temporary pumping of dirty water for dewatering wells during construction.
The two purposes are different and require different pumps. The first will not be discussed
here, because, in rural areas, hand pumps are more appropriate for drinking-water supply in
most cases. The second is described in the following.
B) Range of Use
Submersible pumps can be designed for heads between 5 and 150 m. For dewatering wells
during construction, they are suitable if the water table is 8 m or deeper.
C) Elements of a Pumping System with two Submersible Pumps
A pumping system with a transportable generator and two submersible pumps consists of the
elements shown in the drawing next page.
D) Description and Specifications
In the generator, a diesel engine produces rotational movement and turns the axle of the
attached generator part. Here, the mechanical energy is converted into electrical energy. The
electricity is transported through the electrical cable to the pump in the well. The electrical
engine of the pump converts the electrical energy into rotational movement and turns the
blades of the attached centrifugal pump. The rotating blades suck in the water through the
inlet and press it through the delivery pipe to a higher level (out of the well). As the energy is
converted several times and transported through the electrical cable, there are a great
number of losses and the efficiency of the system is low. (There are four conversions of
energy: fuel - -> mechanical energy = rotation of the generator axle - -> electrical energy - ->
mechanical energy = rotation of pump axle - -> water pressure).
324
Elements of a Pumping System with two Submersible Pumps
Schematic Illustration
The pump in the well always has three connections to the well head:
1. a rope or steel cable bearing the weight of pump and hoses;
2. an electrical cable supplying the energy;
3. a delivery hose or pipe for the water.
When purchasing a submersible pump check the specifications and pay attention to the
following aspects:
- The pump must be designed to pump dirty, sandy and muddy water because the water in
a well is never sand-free during construction.
- The generator for running the pump must be transportable and strong enough for the
pump.
- The pump should be as light as possible for easy handling.
325
- The diameter of the outlet should be reasonable (between 1” and 2”), otherwise, the
delivery hose will be very heavy and difficult to handle.
E) Advantages and Disadvantages
The advantages of a submersible pump for dewatering wells are as follows:
- It is suitable for deep wells.
- It is small and can easily be lowered into the well.
- It is able to pump dirty, sandy and muddy water.
The disadvantages are:
- It needs fuel.
- The efficiency is low.
- The equipment is relatively sophisticated and can break down easily.
- Spare parts are difficult to get.
- It requires great care during operation.
- It occupies space in the well.
- Nobody can work in the well while the pump is operating.
In spite of the disadvantages, the submersible pump is often the only option for dewatering
(deep) wells.
F) Step-by-Step Procedures to Operate Submersible Pumps
For dewatering wells with two submersible pumps, follow these steps:
No
1
Step
Put the generator into the with the shade
exhaust away from the well.
2
Check engine oil and fuel.
3
Lower pumps hanging on rope or steel
cable connected with the hoses. The
pumps should be well submersed, but not
stand on the ground. Connect the
electrical cables to the distribution box of
the generator.
Measure and record well diameter and
water table.
Start the generator with the crank handle.
Remove the handle immediately after the
generator has started. Let it run for 3
minutes.
Record the time.
Switch on the first pump. Listen for a slight
change in the sound of the generator.
Watch if the pump makes a sudden
rotational movement when starting.
Watch if water comes. Switch off if no
water comes.
4
5
6
7
8
9
Switch on the second pump.
10
Watch if water comes. Switch off if no
326
Reasons
Otherwise the generator runs too hot and
gets spoiled. Exhaust fumes are
dangerous (see 8.22/1,3)
If not full, engine oil and fuel need to be
refilled.
The hose and its joints are not strong
enough to carry the pumps’ weight. If
standing on ground, the pump will dig itself
into the sand and get blocked.
This is necessary for calculating the
discharge of the pump (see 8.34).
The generator should be warm before
loaded with pumping work.
see No. 4
If you hear a change of the sound, the
generator supplies electricity to the pump.
If the pump makes a sudden movement,
the impeller started to rotate.
The pumped water has to cool the pump.
If running dry, the pump will become hot
and can be broken within three minutes.
The generator should not be overloaded
with starting both pumps at once, because
the pumps need more power during
starting than during running.
see No. 8.
No
11
12
13
14
15
Step
water comes.
No people should be in the water during
pumping.
If the top of the pump appears above the
water table, lower the pump further.
Switch off immediately when water stops
to flow. Therefore, watch the pump
continuously.
Record time, water table and well
diameter.
Store pumps and generator in dry clean
place in the shade and handle them with
care.
Reasons
If the pump has a short circuit, the person
in the water is in danger.
see No. 8
see No. 8
see No. 4
Sun overheats the machines; rain causes
corrosion.
8.29. Drawing Water from a Well for Human Consumption
There are many different ways to draw water from a well for human consumption. Which is
the best water drawing device?
There is no “best pump” for all conditions everywhere.
Instead, the most suitable solution must be selected for each area, even for each well, again
and again, considering not only technical, but also social aspects.
In the following section, we give suggestions on how to select the suitable method of drawing
water for certain conditions. These suggestions are subjective and based on the given criteria
and priorities.
A) Criteria for Selecting the Suitable Method
We suggest that the following criteria (= guidelines) should guide our choice of the waterlifting device (in the order of their priority):
1. Protection of groundwater in the long run.
2. Durability, maintenance and repair.
3. Protection of health.
4. Provision of water for the majority of the population.
5. Acceptability by the community.
6. Economic suitability.
On No. 1.:
Protection of groundwater in the long run, i.e. preventing the aquifer from being exhausted, is
the first priority. To install a water supply system which draws more water from the aquifer
than is recharged by rain or from other sources, means to deceive the users. They will get
used to the abundant water supply and plan their activities accordingly, only to get into great
trouble when the water table drops. Such installations are also irresponsible for the future
generations. The aquifer might not be able to provide a large water supply in the long run, but
a limited water supply might be possible for generations. See also 8.8/3f.
On No. 2.:
327
To consider durability, maintenance and repair is essential, too. The water supply installation
must have a realistic chance of being kept-up for years. It is easier to reach a remote place
with high-level technology for the short construction period, than to reach it continuously with
middle-level technology for running and maintenance. We need to look honestly into the
question of whether the infrastructure, the fuel supply, the spare parts’ supply and the skilled
labour are available to run and maintain the proposed water supply system. Often, the local
people in the village are more realistic about the issue than planning personnel and
politicians. See also 8.24/2-6.
On No. 3.:
To provide clean and safe water is an obvious criterion (= guideline), although not the first
priority. It comes after the two already mentioned. To provide clean water for a short period
only is no real improvement for the health situation of the users. The water supply in large
areas and for many people is in such a state that the people struggle to get any water rather
than good water. This is a sad, but true fact. Under these circumstances, provision of easily
available and sufficient quantities of any water is already an improvement, even an
improvement in health (enough water for cleaning and washing, less efforts spent on securing
the water supply). Providing clean water alone is not sufficient as well, because the general
situation, poverty and the level of knowledge might prevent the users from keeping the water
clean after taking it from the supply. Therefore, stressing the cleanliness of the water, while
the other factors remain untackled, is not enough. See also 8.5 and 8.6.
On No. 4.:
We have to examine exactly who is to benefit from the proposed water system. We suggest
as a guideline to try to supply water to the majority of the population, rather than to a minority.
It is questionable spending lots of money and resources on high level water supply for a
priviledged minority, rather than a lower level water supply for many. See also 8.2.
On No. 5:
The chosen water supply system must be understood and accepted by the users. However,
this depends very much on, and can be influenced by, relevant education and community
development work. See also 8.38 and 8.39.
On No. 6.:
The system should be within the economic means of the users; if not the installation, then at
least the running costs. See also 8.3.
B) Methods of Drawing Water for Human Consumption from Wells
The diverse water-lifting devices are described in 8.24. Those devices suitable for drawing
water for human consumption can be arranged into three main groups with variations. These
three groups also represent different levels of sophistication:
C) Water-Lifting with Bucket and Rope
The simplest way to lift water with a bucket or another container and rope (see 8.24, No. 1, 2).
1. Advantages
Its advantages are:
- The equipment can be completely local, if necessary, consisting of gourds and ropes
from local fibres.
- No outside input is required.
328
- No maintenance structure is required.
- The method is very reliable.
- No water is going to be wasted because the amount of water pulled is limited.
- Large numbers of animals cannot be watered.(This could also count as a disadvantage).
Therefore, overgrazing due to availability of water cannot occur.
2. Disadvantages
The disadvantages are:
- The water is not protected from pollution.
- The amount of water which can be pulled is very limited.
- The depth from which the water can be pulled is limited.
- The method is tiresome and time consuming.
3. Suitability
Drawing water with bucket and rope fulfils guidelines No. 1, 2, 4, and 6. Guideline No. 5 is
fulfilled in many cases. Guideline No. 3 is not fulfilled in most cases and improvements are
advisable.
Drawing water by bucket and rope is suitable if the infrastructure for hand pump installation,
operation and maintenance is not available in the long run. In that case, improve the situation
within the given circumstances by
- providing enough wells;
- constructing the wells with a lining and, thus, digging deep into the water table;
- providing an elevated well mouth with a lid;
- providing a proper concrete apron;
- conducting a health education campaign.
D) Water-Lifting with a Hand Pump
Hand operated pumps or other simple devices are the next level of technology for lifting water
(see 8.24, No. 3-14, 16-18,22).
1. Advantages
The advantages are
- The well can be sealed and protected from pollution.
- The maintenance is relatively simple and local people might be able to learn it.
- No fuel is required.
- The method is less tiresome for the users than C).
- No water is going to be wasted because the amount of water pumped is limited.
- Large numbers of animals cannot be watered.(This could also count as disadvantage).
Therefore, overgrazing due to availability of water cannot occur.
- Greater depth can be reached than with the method under C).
2. Disadvantages
329
The disadvantages are
- The pump might be available only from abroad.
- The spare parts’ supply must be secured. It might require foreign currency and an
organisation to acquire it.
- People able to repair the pump must be available.
- A higher degree of organisation within the community is required than for the method
under C).
- The method is more expensive than C).
- Only one person can draw water at a time.
- The depth is limited to 70-80 m, in exceptional cases up to 110 m.
- Some people can try to get control and make private profit from a hand pump on cost of
the community.
3. Suitability
Drawing water with a hand pump fulfils the guidelines No. 1 and 4. Guideline No. 2 is fulfilled
if the infrastructure for maintenance is available. Guideline No. 3 is fulfilled if the well is
properly constructed and the platform has no cracks. Guideline No. 5 depends on information
and health education. Guideline No. 6 depends on the resources of the community.
To achieve water supply by hand pump is a goal for all rural communities and many urban
communities.
Install a hand pump only if
- operation and maintenance can be secured in the long run;
- the community is organised to take the responsibility of the pump;
- women are being trained for hand pump caretaking and repair;
- there are enough resources to construct the well head properly;
- the hand pump can be installed properly; When installing a hand pump, take care
- to provide enough wells;
- to conduct a health education campaign;
Do not install a hand pump if maintenance cannot be secured in the long run.
Water-Lifting with Fuel Powered Pumps into an Elevated Tank
This method is considerably more sophisticated than the two before. The water is pumped
into an elevated tank from where it is supplied in pipes either directly to households or to
public taps (see 8.24, No. 20, 23, 27-29, 31,32).
1. Advantages
The advantages are
- The well can be protected from pollution.
- Water can be pumped from greater depths than by methods C) and D).
- Piped water supply becomes possible.
- The method is less tiresome for the users than methods C) or D).
2. Disadvantages
330
The disadvantages are
- The pump and other parts of the installation most likely come from abroad.
- A constant supply of fuel is required.
- The spare parts’ supply must be secured, most likely from abroad.
- Highly skilled people are required for installation and maintenance.
- Skilled labour is required for the daily running.
- A structure is required to organise installation, supplies and maintenance.
- The costs are very high.
- Waste of water is very likely.
- There is a danger of exhausting the aquifer and of lowering the water table in the long
run.
- Overgrazing and desertification are possible if a large number animals are attracted by
the well.
3. Suitability
Water supply by fuel powered engine pump and elevated tank should fulfil guideline No. 3.
Whether the method fulfills the other guidelines, depends on the situation and has to be
questioned.
Water supply by fuel powered engine pumps and elevated tanks is not a reachable goal for all
rural communities, and is a reachable goal for some urban communities.
Install such a system only if
- it does not exhaust the groundwater in the long run;
- operation and maintenance can be secured in the long run;
- fuel supply can be secured in the long run;
- no flush latrines are to be supplied by the system and, thereby, large amounts of water
wasted; see also 8.37/7 and 9.8/2;
- the community is organised to take responsibility for the system;
- women are being trained for operation and maintenance;
- the community can afford the system;
- the system is safeguarded against being exploited by a few people;
- you have to supply densely populated town areas with public taps
When installing this system, take care to conduct a health education campaign. Do not install
this system at all in scarcely populated rural areas with many animals because of the danger
of overgrazing and desertification.
331
8.30. Hand Pump Parts and Functions
It is very important for a technician to know the names of the parts of a hand pump and to
understand their functions. This background knowledge will enable her/him to understand why
the hand pump has to be installed and repaired in a certain way.
The parts and functions are explained here for the INDIA MARK II hand pump; other hand
pumps of a similar type consist of principally the same parts. The different types of
handpumps are explained in detail in No. 18 of the bibliography.
A) Parts of Pump Head Assembly
For learning about the parts of a hand pump, disassemble a pump and get familiar with the
parts.
CROSS-SECTION
332
B) Function of Pump Head Assembly
The operation of a hand pump has two distinct and opposite phases:
1. Phase
- handle moving downwards
- rod moving upwards
2. Phase
- handle moving upwards
- rod moving downwards
UP and DOWN movement of handle
results in
DOWN and UP movement of rod.
333
The pump head assembly, as shown here, has a chain link. The rod is lifted by an active
downwards stroke of the handle. The rod moves downwards and, thus, lifts the handle by
itself because the weight of all the rods together overcomes the friction and the weight of the
handle. This is the case if the pump cylinder is installed at about 20 m or deeper.
If the cylinder is installed in a depth less than that, the weight of the rods is not enough, and
the flexible chain cannot push the rods down. In that case, a solid link is required between the
handle and the rod so that the upward movement of the handle can push the rod downwards.
The disadvantage of the solid link connection is that there will be a slight lateral (= horizontal)
movement of the rod with each stroke. The pump head with solid link is suitable for wells up
to 20-25 m depth.
C) Parts of the Cylinder Assembly
Disassemble a pump cylinder and get familiar with its parts:
D) Function of the Cylinder Assembly
The cylinder operates in two distinct phases as well:
334
1. Phase
Schematic Illustration; some details left for sake of clarity; valves in side-view.
How do the valves open and close?
1. The water in the pipe tries to move downwards by gravity → This closes the upper valve.
2. The plunger moving upwards creates suction → This opens the bottom valve.
335
2. Phase
Schematic Illustration: sane details left for sake of clarity; valves in side-view.
How do the valves open and close?
1. The water in the cylinder tries to move downwards by gravity → This closes the bottom
valve.
2. Rod and plunger are moving downwards → The resistance of the water in the cylinder
opens the upper valve.
The two valves open and close alternately and, thus, the water is lifted in steps (not
continuously!). The valve (consisting of seat, rubber seating, and valve guide) moves up and
down (open and closed). It is essential that the valves close watertight. This is ensured by the
rubber seatings of the valves which must be intact.
336
The pump buckets (= leather cups) provide the watertight sealing between the plunger
moving up and down, and the inner wall of the cylinder (with a brass liner). Although the pump
buckets seal, they allow the plunger to move. If the pump buckets are worn out, the sealing
will not be complete and the yield of the pump will decrease. The pump buckets are the parts
which usually wear out the quickest, especially, if there is sand in the cylinder due to improper
installation. They need to be replaced regularly.
8.31. Hand Pump Installation
There are specific manuals for each type of hand pump, published by the manufacturers (e.g.
No. 22 in the bibliography for the India Mark II hand pump). Follow the steps of the manual
when installing or repairing a hand pump. Some general principles, valid for all kinds of
different pumps, are compiled here.
A) Lowering and Lifting the Riser Main Pipe
During installation and repair the riser main pipe (= rising main = = rising pipe) has to be
lowered into and lifted from the well. This can be done in different ways depending on the
depth of the well.
1. Blocking the Riser Main Pipe
While lowering the riser main pipe, one must stop in between to join the next following pipe.
For this operation, the riser main pipe must be blocked temporarily. This can be done
- by a special self-locking clamp,
337
- by an ordinary pipe vice (see 6.3/34), laid across the pump body,
- by pushing a socket (9 3” over the two handles of a pipe wrench (6.3/34)
In any case, make sure that a socket is fixed to the top end of the riser main pipe. This is an
extra precaution.
The lowering itself can be done by one of the following methods:
2. Lifting by Hand
For very shallow wells (up to about 10
m) the riser main pipe (together with the cylinder and the rods) can be lifted by hand directly.
Enough and well coordinated people are necessary for that.
3. Lifting by Lifting Spanners
For medium depth wells (up to 35-40 m), the pipes can be lifted with 3 to 4 lifting spanners
which hold the pipe by friction and provide an advantageous lever arm.
338
Lifting spanners can also be manufactured locally from metal pipe Ø 1”
The technicians place the lifting spanners around the riser main pipe and get hold of it by
pressing the handle upwards. They must be well coordinated.
4. Lifting with Lifting Spanners and Simple Scaffold
For deep wells, lifting with lifting spanners can be made easier with a scaffold made from a
pipe Ø 2” with steps. This scaffold is fixed to the pump body with U-bolts. A technician at the
top can easily direct the pipes while lowering or lifting.
Design: Norwegian Church Aid - Sudan Programme, Torit, Sudan
339
Additionally, a small winch can be fixed on the scaffold and the steel cable directed over a
roller on the top.
5. Lifting with Tripod, Winch and Steel Cable
It is difficult to lift pipes from depths more than 40 m. In this case a light weight tripod (see
8.17/13) and a small winch can help. The riser main pipe is fixed to the steel cable with a
chain pipe vice (see 6.3/34).
B) Tightening the Joints of the Riser Main Pipe
Watertight joints of the riser main pipe are essential, otherwise the yield of the pump will
decrease. Tight joints can be achieved with the following measures:
1. Clean all threads with a wire brush and lay the pipes on two pieces of timber, not
directly on the ground. The threads must be completely sand-free when you join them.
Sand on the thread prevents the thread from fully closing, and thus causes leakage.
Constant leakage causes corrosion, and the pipe is likely to break sooner at the thread.
CROSS-SECTION TROUGH JOINT WITH SAND
340
2. Smear jointing compound on the thread or cover the thread by thread-tape before
tightening. This materials fill the tiny voids between the threads and make the joint
watertight.
3. Tighten all joints properly, but do not overdo it. Handle the pipe wrenches as described
in 8.32/14.
C) Handling the Pump Rods
Handle the pump rods as follows:
1. Clean the threads of all pump rods.
2. Grease the threads if they are corroded.
3. Take great care not to bend a pump rod.
4. Do not install any bent pump rod.
5. Tighten the joints of the rods properly.
6. Hold the rod by a rod-vice when you cut it to length, to avoid bending.
7. When threading the pump rod, prevent cuttings from falling into the riser main pipe by a
piece of cloth (cuttings quickly wear out the pump buckets).
D) Handling the Pump Cylinder
Handle the pump cylinder as follows:
1. Check it before you install it even if it is new.
2. Open the cylinder and the plunger and tie all elements properly.
3. Tighten the valve seats, but do not squeeze the rubber seatings.
E) Handling the Pump Head
Handle the pump head as follows:
1. Only untie the pump head as much as necessary for installation. Do not dismantle axle
and handle unnecessarily.
2. Grease the chain properly.
3. Grease the threads of all outside bolts and nuts to prevent corrosion due to rain. Thus it
will be easy to open them any time.
F) Locating the Pump Cylinder
The cylinder must be installed at different positions in a borehole and in a hand dug well.
1. Pump Cylinder in a Borehole
The bottom of a borehole is not closed with a filter. Therefore, never install a cylinder in a
borehole less than 6 m from the bottom of the borehole. Apart from that, install in a borehole a
number of full length (3m) pipes, because it does not matter if the cylinder is higher or lower
by 1 or 2 m as the water column is normally high. Join an extra pipe to the bottom of the
cylinder. This forces the water to enter through the pipe. Eventually, sand would settle and
clean water will enter the cylinder.
341
Schematic Illustration
2. Pump Cylinder in a Hand Dug Well
The water column in a hand dug well is limited and, therefore, the cylinder has to be installed
as deep as possible to utilize the water reservoir fully.
342
There must be a filter in the well bottom (see 8.20/1f). Install the cylinder so that its bottom is
about 15-20 cm above the top of the filter. This will most probably require cutting and
threading of one riser main pipe. To get the correct length, you can proceed as follows:
- Measure the distance between the top of the pump body and the top of the filter with a
plumb loaded measuring tape.
SCALE 1:80
- Lay the measuring tape on flat ground. Lay the pump cylinder and the pipes with sockets
beside it. Overlap them according to how they will be tightened. Leave 15 cm for the gap
between filter and cylinder. Add 3 cm for the thread connection with the water tank.
Not to scale!
- Mark where you have to cut the last pipe.
Be very careful when determining the length of the last pipe. Too short means that you waste
a part of the water reservoir and the pump might unnecessarily run dry during dry season.
Too long means that the cylinder might sit on the filter. By the method above you are less
likely to make mistakes than by calculation.
343
8.32. Basic Plumbing
Plumbing is the installation and repair of pipe systems for water supply (or other purposes),
like a hand pump or the water distribution system in a house. The most basic knowledge
about plumbing is compiled here.
A) Threads
The different types of threads for both bolts/rods and pipes are described and compared in
the following chapters.
1. Thread Types
Threads can be differentiated according to six pairs of opposites:
a) Internal/External Threads
Name(s)
Internal Thread
= Female Thread
External Thread
= Male Thread
to cut a thread
= to tap a thread
tap
tap wrench
to cut a thread
drawing
thread cutting operation
tool for thread cutting
handle of thread cutter
die
die stock
= die handle
Internal and external threads of the same size fit together and can be screwed together to
form a joint.
b) Right Hand/Left Hand Threads
Right hand threads are tightened clockwise, left hand threads opposite (= anti-clockwise).
Right hand threads are usually used, left hand threads are not common.
c) Parallel/Taper Threads
A parallel thread (= cylindrical thread = straight thread) has the same diameter from beginning
to end. The threads look clearly cut all over.
344
A taper thread (= tapered thread = conical thread) is growing gradually smaller towards one
end like a cone. The slope of the thread is the taper/length of thread, e.g. 1:16. A taper thread
can easily be recognized because it looks imperfect at the end.
Bolts and nuts have always parallel threads to ensure maximum transmission of force along
the full length. Pipes can have parallel or taper threads. Tapered pipe threads are much more
common, because they are easily tightened watertight to avoid leakage. Tapered pipe threads
do not have a high resistance against bending. In emergency cases, a tapered thread can be
screwed to a parallel thread of the same size, but the joint will not fit exactly.
d) Coarse/Fine Threads
Coarse threads have fewer threads per inch than fine threads. Coarse threads are more
common, fine threads can transmit more force. Whether a thread is coarse or fine is indicated
either by the pitch or the number of threads per inch (= TPI).
The pitch is the distance between two threads and indicates how dense the total thread is
(see drawing next page).
Metric threads are marked by their pitch:
pitch (in mm) =
1
No. of threads per mm
345
For threads in inches, the following is valid:
pitch (in inch) =
1
1
=
No. of threads per inch TPI
For threads in inches, the TPI is indicated.
e) Threads with Sharp Edged Profile/Threads with Rounded Edged Profile
Threads can be cut with either sharp edges or with rounded edges:
Sharp edges are more common. Threads with rounded edges are stronger, but uncommon.
f) Threads for Bolts and Nuts/Threads for Pipes
346
Threads can be categorized in two main groups: threads for bolts and nuts (and rods), and
threads for pipes. Within the two groups a variety of different threads exists according to
different countries and traditions. The main thread types are listed on the following pages.
2. Thread Standards for Bolts and Nuts
The purpose of a bolt is to press the objects between the nuts together and to connect them
thus by friction. A bolt has to transmit force.
The two parts joined together are shown in Cross-Section, bolt and nut are shown in SideView;
Sometimes, the following signs are used for a bolt and nuts:
See also 6.1/17,19,23.
The function of the washer is to prevent the nut from getting loose.
Threads for bolts and nuts are both internal (on the nut) and external (on the bolt). Threads
347
for bolts and nuts are mostly right hand, but left hand threads can be found, too.
Threads for bolts and nuts are always parallel.
Thus, maximum force can be transmitted along the full length of the thread; the thread is
exactly fitting.
Threads for bolts and nuts can be coarse or fine; they can have sharp or rounded edges.
The following thread types are used for bolts and nuts (for sizes see thread tables):
a) Metric Coarse Threads M
- thread for bolts and nuts;
- measured in metric system in mm;
- specification (example):
M 10 × 1.5 (= major Ø in mm × pitch in mm)
- both internal and external threads;
- mostly right hand threads; left hand threads uncommon;
- always parallel thread;
- coarse thread;
- sharp edged profile with 60°:
- common in Sudan and on the European continent; uncommon in USA and Britain.
b) Metric Fine Threads M
- thread for bolts and nuts;
- measured in metric system in mm;
- specification (example):
M 10 × 0.75 (= major Ø in mm × pitch in mm), or MF 10 × 0.75
Note that some diameters can possibly have different pitches, e.g. there are three different
fine threads with Ø 10:
M 10 × 0.75
M 10 × 1
M 10 × 1.25
- both internal and external threads;
- mostly right hand threads; left hand threads are uncommon;
- always parallel thread;
- fine thread;
- sharp edged profile with 60°:
- common in Sudan and on the European continent; uncommon in USA and Britain.
c) Unified Coarse Threads UNC
- thread for bolts and nuts;
- measured in inches;
- specification (example):
UNC No. 12 7/32 × 24, or
348
UNC
1
× 13 (= thread Ø in inch × thread per inch [TPI])
2
- both internal and external threads;
- mostly right hand threads; left hand threads uncommon;
- always parallel thread;
- coarse thread;
- sharp edged profile with 60°:
- common in USA and Britain; less common in Sudan; uncommon on the European continent.
d) Unified Fine Threads UNF
- thread for bolts and nuts;
- measured in inches;
- specification (example):
UNF No. 12 7/32 × 28, or
UNF
1
× 20 (= thread Ø in inch × thread per inch [TPI])
2
- both internal and external threads;
- mostly right hand threads; left hand threads uncommon;
- always parallel thread;
- fine thread;
- sharp edged profile with 60°:
- common in USA and Britain; less common in Sudan; uncommon on the European continent.
e) Whitworth Coarse Threads W
- thread for bolts and nuts;
- measured in inches;
- specification (example):
W
1
× 12 (= thread Ø in inch × thread per inch [TPI])
2
Note that the diameters are the same as for UNC, but the TPI can differ sometimes;
- both internal and external threads;
- mostly right hand threads; left hand threads uncommon;
- always parallel thread;
- coarse thread;
- round edged profile with 55°:
therefore very strong;
- up to very large diameters (4”);
- common in Britain; uncommon in other places.
3. Thread Standards for Pipes
The purpose of a pipe thread is to join two pieces of pipe in such a way that the transported
fluid or gas does not leak. Watertightness or airtightness are more important than strength.
Pipe threads are both internal (in the socket) and external (on the pipe). They are mostly right
hand, left hand only in exceptional cases.
349
Pipe threads can be both parallel and taper. Tapered pipe threads are much more common
because of their water tightness and they are required for water and gas installations. When
buying thread cutting tools, you have to indicate if you want parallel or taper pipe threading
tools.
Pipe threads are mostly coarse, fine pipe threads are very rare. Pipe threads can have sharp
edged and round edged profiles.
The following pipe threads are most common (for sizes see thread tables):
a) Whitworth Parallel Pipe Threads BSP
- thread for pipes;
- measured in inch;
- specification (example):
1
4
1
BSP R 1 , parallel, or
4
1
R 1 , parallel, or
4
1
R 1 , DIN 259 z (= German specification)
4
BSP R 1 × 11, parallel (= nominal Ø in inch × thread per inch [TPI]), or
BSP stands for British Standard Pipe. The figure given is the nominal diameter in inch; it is
neither the internal nor the external diameter of the pipe. The number of threads per inch
(TPI) needs not to be indicated, because for each nominal diameter only one TPI is
possible.
- both internal and external threads;
- mostly right hand threads, left hand threads only in exceptional cases;
- coarse thread;
- round edged profile with 55°:
- common in Sudan and Europe, but less common than tapered pipe threads.
b) Whitworth Taper Pipe Threads BSP
- thread for pipes;
- measured in inch;
- specification (example):
1
× 11, taper (= nominal Ø in inch × thread per inch [TPI]), or
4
1
BSP R 1 , taper, or
4
1
R 1 , taper, or
4
1
R 1 , DIN 2999 k 1:16 (= German specification)
4
BSP R 1
see also 8.32/9;
350
- both internal and external threads;
- mostly right hand threads; left hand threads only in exceptional cases;
- coarse thread;
- round edged profile with 55°:
- very common for pipe threads in Sudan and Europe?
c) (American) National Parallel Pipe Threads NPSF
- thread for pipes;
- measured in inch;
- specification (example):
1
4
1
NPSF 1 × 11.5 (= nominal Ø in inch × threads per inch [TPI])
4
NPSF 1 , or
see also 8.32/9; the TPI of the NPSF pipe thread is different from the TPI of a BSP pipe of
the same diameter;
- both internal and external threads;
- mostly right hand threads; left hand threads only in exceptional cases;
- parallel thread;
- coarse thread;
- sharp edged profile with 60°:
- common in USA.
d) (American) National Taper Pipe Threads NPT
- thread for pipes;
- measured in inch;
- specification (example):
1
4
1
NPT 1 × 11.5 (= nominal Ø in inch × thread per inch [TPI])
4
NPT 1 , or
see also 8.32/9 and 10;
- both internal and external threads;
- mostly right hand threads; left hand threads only in exceptional cases;
- taper thread;
- coarse thread;
- sharp edged profile with 60°:
- common in USA.
4. Pipe Measurements
Pipes are indicated by the diameter in inch. Note that this diameter is a nominal diameter and
is neither the inside nor the outside diameter, e.g.
351
1
4
pipe Ø 1 “ = 31.75 mm
outside Ø = 41.91 mm
inside Ø = 34 mm
The diameter can be abbreviated as
Ø 3” = nominal diameter
Ø 3” OD = outside diameter = external diameter
Ø 3” ID = inside diameter = internal diameter
Measure the outside and inside diameter of a pipe with a caliper (see 6.3/2).
Measure the thread type with a thread gauge (see 6.3/38).
B) Basic Operations of Plumbing
Some basic operations of plumbing are described in the following:
1. Cutting with a Hacksaw
When cutting a metal piece with a hacksaw, follow these steps:
- Fix the part to be cut in a vice.
- Select the right type of hacksaw blade according to the size of the part to be cut (see
6.3/28).
- Never change the blade in the middle of one cut. (A worn out blade cuts a narrower slot
than a new blade. The new blade would be quickly spoilt in the narrow slot.) Take a new
blade if the old one is not good enough for a full cut.
- Tighten the blade in the hacksaw frame.
- Mark where to cut.
- Hold the hacksaw straight.
- Use the full length of the blade in even movements.
- Press downwards when pushing the hacksaw forward. Do not press when pulling the
saw back. The blade must be fixed to the frame accordingly. See also 6.3/26f.
Correct Use of Hacksaw
2. Pipe Cutting
It is very difficult to cut a pipe straight with a hacksaw. Instead, use a pipe cutter. Follow these
352
steps:
- Fix the pipe in a pipe vice.
- Mark where to cut.
- Push the pipe cutter (see 6.3/36) onto the pipe.
- Tighten it until the cutting wheel touches the pipe.
- Oil the cut.
- Turn the pipe cutter one or two turns until slightly loose.
- Tighten the cutting wheel again.
- Cut another turn.
- Continue like this with constant oiling for cooling until the pipe is cut.
- Clean the chips away with a flat file.
3. Thread Cutting
Thread-cutting oil is needed for threading. There are two types of oil for thread cutting. Use
the thread-cutting oil for drinking water (without any poison) for water supply systems and
pump installation. Use the other type for all other threads.
Internal threads are normally cut in workshops and factories. For ordinary water supply work,
external threads have to be cut. When cutting external threads, follow these steps, both for
bolts and pipes(see also 6.3/36-41).
- Cut the bolt or pipe straight, i.e. orthogonally to its axis. Cut a pipe with a pipe cutter.
- File the end conically(= with a tapered end):
- Fix the bolt or pipe firmly in a vice.
- Take the die with the correct size and fix it in the die stock. The tapered end of the die
has to start the threading (both for bolts and pipes).
- Start cutting the thread(clockwise for right hand thread). Hold the handle vertical to the
353
bolt/pipe. Oil continuously with thread-cutting oil.
- Turn one full turn (or until turning becomes difficult). Turn a quarter turn backwards to
remove the chips. Turn another full turn forward and so on.
- Never use force.
- Continuously oil.
- When the thread is long enough, remove the chips, and turn the die loosely backwards
until it is off the thread. When using a thread cutter with chaser die, open the dies and you
can remove the tool without screwing back.
- Clean the thread and the die.
- The thread is of good quality if you can screw the nut or the socket easily onto the thread.
4. Using Pipe Wrenches (see also 6.3/34)
Pipe wrenches are used to tie or untie pipe connections. Use them like this:
- Take the pipe between the two jaws of the pipe wrench. The two jaws must be parallel,
as well as the handles.
- Tighten the positioning screw.
354
- Grip the two handles properly. If you have correctly adjusted the wrench, the two handles
will be near enough to be easily pressed together, but not too near.
- Screw the pipe by turning the wrench as indicated in the drawing. For tightening a pipe
and socket, the two wrenches must be held in the opposite way:
- When installing several pipes and sockets after each other, use always the same wrench
for the socket and the other for the pipe. Thus, you will not have to re-adjust the wrenches
every time.
- Never turn the serrated (= toothed) jaws of the wrench on the pipe, because this
damages the teeth of the jaws as well as the pipe. The pipe will start to corrode at those
spots. Good plumbing work leaves hardly any marks on the pipe.
C) Pipe Joints
Pipes can be joined together by different methods. The joining pieces are called fittings.
Different types of pipe joints and other fittings are compiled here.
1. Male and Female Pipe Threads
Pipes with male and female threads can be
joined directly.
2. Socket (= Coupling)
for joining tapered pipe threads. You must be
able to turn one of the pipes for connecting.
355
3. Socket with Backnut
for pipes with parallel threads. The backnut
ensures water tightness.
4. Nipple
for joining two pipes with internal threads.
5. Reducer
for joining two pipes with different diameter and
internal threads.
356
6. Reducer Socket
for joining two pieces with different diameter
and external threads.
7. Tee-Joint (= Tee-Piece)
for branching pipes.
8. Elbow for corners.
9. M & F - Elbow
male-female elbow, for corners.
357
10. Pipe Cap
for closing a dead-end pipe with external
thread.
11. Plug
for closing a dead-end pipe with internal thread.
12. Union Joint
for connecting already installed pipes which
cannot be turned.
358
13. Flange Joint
for large diameter pipes (Ø 3” and more).
14. Welded Joint
for permanent Installations.
15. Hose Connection
for connecting a hose to a pump or a tap with
thread.
16. Dog Clutch
for quick connection of two pipes or hoses with
dog clutches by a quarter turn, e.g. for fire
brigade.
359
8.33. Hand Pump Caretaking
The crucial question in operating a water point is: Whom does the water point belong to? The
caretaker? The Community? The contractor? The ownership will determine whom the water
point will serve and who will be favoured.
A hand pump caretaker is essential for the functioning of a hand pump. She/he has technical
and social duties and functions.
A) Daily Technical Duties
No.
1
2
3
4
Duty
Sweep
the
platform
and
the
surroundings. Keep the drainage free.
Open and lock the pump according to
opening hours.
Pump some water and check if
operation and discharge are normal.
Report break-down of the pump
immediately and lock the pump.
Reasons
A water point needs to be clean in order to
provide clean water.
The pump shall be used according to the
regulations set up by the community.
Any break-down is easier to repair if
discovered immediately.
B) Weekly Technical Duties
No.
1
Grease the chain.
Duty
2
Tighten all bolts.
3
Check if the platform has any cracks and
repair it with cement mortar.
Reasons
A greased chain lasts longer and makes
operation easier.
Loose bolts cause unnecessary movement
and lead to breakage.
Cracks allow dirty water to enter the well.
C) Social Duties
No
1
Duty
Be in time and keep to opening hours.
2
3
Behave politely.
Make sure that the queue is kept
correctly, and nobody favourised.
Do not allow people to pump if they do
not join the queue.
Collect the money for the water.
Do not give water to anybody free of
charge or for less than the community
decided.
Deliver the money collected correctly.
Teach the users to operate the pump
correctly.
Prevent the users from dirtying the
platform and surroundings.
Be honest and just.
4
5
6
7
8
9
10
Reasons
To be hand pump caretaker means to serve
the community. People will appreciate and
respect you if the] see that you are reliable,
honest and just.
If the above duties are fulfilled, the hand pump will serve the community members equally and
justly. This is only possible if the community controls the hand pump and the caretaker by a
360
functioning committee. In this case, the income can be used for maintenance and other
community projects (e.g. building new wells or latrines), beside a reasonable “salary” for the
caretaker.
At present, few caretakers in Juba act according to these principles. The reason is first, that
somebody who has not paid for the well claims ownership over the hand pump(or is given it
as a contractor by the government) and, thus, makes profit out of the users and even abuses
them. Secondly, the users act individually and do not organise themselves as a community
and accept the present situation without readiness for commitment and change.
See also questionnaire about water sources and hand pump use, 4.23/5-9.
8.34. Calculation of Pump Discharge
It is important to know the yield of every pump
- for observation (any decrease of the yield means technical problems in the pump and
requires maintenance).
- for estimating the required time to pump a well empty;
- for comparing different types of pumps.
There are special devices to measure the waterflow in a pipe and, thus, the yield of a pump,
but these are mostly not available. Therefore, we have to measure the yield of a pump by
other, simple methods.
A) Units of Pump Discharge
The discharge or yield of a pump can be expressed in different units:
l
=
sec
l /sec
= l ps
= litre per second
l
=
min
l /min
= l pm
= litre per minute
l
=
h
l /h
= l ph
= litre per hour
m3
=
h
m3/h
= m3ph
= cubic metre per hour
m3
=
min
m3/min
= m3pmin
= cubic metre per minute
The different units are connected as follows:
1 l /sec = 60 l /min = 3,600 l /h = 3.6 m3/h = 0.06 m3/min
1 l /min = 60 l /h = 0.06 m3/h = 0.001 m3/min
Use this transformation table to change one unit to another:
361
If you want
to
change
these units
t/sec
l /min
l /h
m3/h
m3/min
l /sec
l /min
x 60
÷ 60
÷ 3,600
÷ 3.6
÷ 16.7
to these:
l /h
× 3,600
× 60
÷ 60
÷ 16.7
÷ 1,000
× 1,000
× 60,000
m3/h
× 3.6
m3/min
÷ 16.7
÷ 16.7
÷ 1,000
÷ 1,000
÷ 60,000
÷ 60
× 60
How to use a transformation table is explained on 5.3/1.
B) First Method to Measure the Yield of a Pump
No.
1.
2.
3.
4.
Step
Record the time you start pumping and
measure the water table.
Record the time you stop pumping and
measure the water table.
Measure the diameter of the well at the
water table.
Calculate the time needed for pumping
Example
tstart = 9.31, WTstart = 12.05 m
tend = 9.45, WTend = 12.65 m
Ø = 1.20 m
t = 45 min - 31 min = 14 min
t = tend - tstart
5.
For how to calculate a period of time
see 5.8/3.
Calculate the volume of water pumped
from the well (see 5.6/2):
d = diameter
r = radius
h = drawdown = WTend - Wtstart
1
V=
× π × d2 × h = V × r 2 × h
4
6.
π = 3.14
Calculate the yield:
yield =
7.
d = 1.20 m
h = 12.65 m - 12.05 m = 0.60 m
V=
m3
Q=
volume
V
; Q=
time
t
Transform the result into m3/h.
1
× 3.14 × 1.202 m2 × 0.60 m = 0.678
4
0.678 m3
= 0.0484 m3 /min
14 min
Q = 0.0484 × 60 m3/h = 2.90 m3/h
If the diameter when starting pumping is not the same as the diameter when ending pumping,
take the average diameter for an approximate calculation:
d=
1
(dstart + dend )
2
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C) Second Method to Measure the Yield of a Pump
No.
1.
2.
3.
4.
5.
Step
Record the time and start to pour the water
discharged by the pump into an empty
barrel.
Record the exact time in seconds when the
barrel is full.
Calculate the time needed for filling the
barrel (see 5.8/3):
t = tend - tstart
Determine, measure or calculate the
volume of the barrel(see 5.6)
Calculate the yield:
yield =
6.
volume
V
; Q=
time
t
Transform the result into l/min with the
transformation table.
Transform the result into m3/h.
7.
Example
tstart = 8.06, 0 sec
tend = 8.07, 25 sec
t = 1 min + 25 sec
= 60 sec + 25 sec
= 85 sec
V = 200 l
Q=
200 l
= 2.35 l/sec
85 sec
Q = 2.35 × 60 l /min = 141 l /min
Q = 2.35 × 3.6 m3/h = 8.46 m3/h
D) Yields of Some Pumps for Comparison
Average yields of some pumps are roughly estimated here and expressed in different units for
comparison. It is advisable to memorize pump yields only in one chosen unit, e.g. m3/h.
No.
Pump
1.
2.
3.
4.
India Mark II hand pump
submersible pump HOMA 725 DHD
diaphragm pump, handoperated
petrol suction pump Honda WA 30X
Average Yield (Approximately)
m3/h
l /sec
l /min
l /h
0.22
13.3
800
0.8
0.83
50
3,000
3
2.22
133
8,000
8
8.33
500
30,000
30
8.35. Spring Protection
This chapter compiles the most basic information about spring protection. For more details
see in the bibliography No. 44, 45, 46.
A) Purpose of Spring Protection
A spring is a place where water is naturally issued from the ground by continuous flow. A
spring protection is being artificially constructed to serve the following purposes:
1. It shall protect the spring from contamination.
2. It shall improve the accessibility of the spring for the users.
3. It shall increase the water flow, if possible.
B) Different Spring Types
Springs can be differentiated according to the shape of the opening the water flows from. We
differentiate seepage springs, where the water comes out of many tiny openings, and springs
with a single opening like a fracture or a round hole.
However, springs are mainly differentiated according to the type of aquifer (open or confined
aquifer) and the form of the surface. So, we differentiate the following types:
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OVERVIEW ABOUT SPRING TYPES
No
Construction
Type of Water Outlet
1
Spring Type
Gravity Springs
Gravity Depression Spring
- preferably as well
2
Gravity Overflow Spring
- without springbox, or
- with springbox with open side, or
- with seepage trench and spring
box, or
- as combination spring-well, or
- as horizontal well
- for seepage spring
or single opening
- for single opening
- for single opening
- for seepage spring
- for seepage spring
or single opening
- for single opening
- with springbox with open bottom
- for single opening
- with springbox with open sides,
or
- with seepage trench and
springbox
- for single opening
- for seepage spring
3
4
Artesian Springs
Artesian
Depression
Spring
Artesian Overflow Spring
The different spring types are briefly introduced in the following:
1. Gravity Depression Springs
Gravity depression springs occur where groundwater emerges at the surface because an
impervious (= impermeable) layer prevents it from seeping downwards. A gravity depression
spring emerges in a sunk area (= depression). It usually has a very small yield and is difficult
to seal against contamination. Its presence shows the level of the water table. Water can be
extracted safely if a well is constructed nearby on a higher ground.
2. Gravity Overflow Springs
The gravity overflow spring usually occurs on slopy ground as a hillside spring. Its flow
changes with variations of the water table during the different seasons.
364
3. Artesian Depression Springs
Artesian depression springs occur where groundwater emerges at the surface after being
confined (= shut up, kept) between two impermeable layers. The water emerges due to the
internal pressure within the confined aquifer. The yield is usually very consistent and higher
than of a gravity depression spring. An artesian depression spring emerges in a sunk area. A
spring box with an open bottom is required for protection. See also 8.8/2.
4. Artesian Overflow Springs
At an artesian overflow spring, the confined aquifer emerges at a hillside through a fracture in
rock or an opening in the impermeable layer. The water flow is usually very constant. They
are a very good source for community water supply, because they are protected from
contamination by the overlying impermeable layer. If the spring flows through a single
opening, a spring box with open side is suitable. If the water flows out through several
openings, seepage trenches become necessary. See also 8.8/2.
365
C) Different Spring Protection Designs
The different types of designs how to protect a spring are described in the following. Some
designs are suitable for different types of springs.
1. Spring without Springbox
A spring without a springbox, but protected, consists of an impervious retaining wall with an
outlet backfilled with stones and covered with puddled clay. It is suitable for gravity overflow
wells with a single opening.
2. Spring with Springbox with Open Side
A springbox (= chamber = intake box = collection box) serves for collecting and storing the
water. It can be built from concrete (with one side open), from masonry (with one side built
without mortar), or from a concrete ring (with one side open or as filter). It has a removable,
watertight, and lockable concrete lid. It is suitable for gravity overflow springs or for artesian
overflow springs.
366
3. Spring Box with Open Bottom
If a spring flows from a single opening on more or less level ground, a springbox with an open
bottom is suitable. This is the case for artesian depression springs. The box can be built on
site from concrete or bricks, or a concrete ring can be used.
4. Spring with Infiltration Trenches and Springbox
If a gravity or artesian overflow spring occurs for a distance along the hillside, the water must
be collected with infiltration trenches. They are dug deep into the hillside to contact the aquifer
even in dry season. Slotted plastic pipes or short clay pipes surrounded with rocks and gravel
collect the water and pipe it to the spring box. The pipes must have a slope. The openings on
the pipes must be big enough to allow water to enter, but small enough to keep out sediments
and to prevent blockage. Vertical clean-out pipes connected with elbows to the end of the
collectors extend a little above ground and are capped. They can be used to clean the system
by flushing it.
It is important to collect all water and to prevent the spring from flowing around or under the
construction and wash it out. The anti-seepage wall (= cut-off wall) prevents loss of water due
to underflow. It must reach into the impervious layer. Alternatively, it can be made from
compacted clay which acts as a dam.
367
Spring with Infiltration Trenches and Springbox
LAYOUT PLAN
368
5. Horizontal Well
A horizontal well is suitable for a gravity overflow spring if the aquifer has a steep slope
following the ground surface. A pipe with an open end or a perforated drive-point is driven into
the aquifer horizontally and sealed all around.
6. Combination Spring-Well
If a gravity overflow spring may dry up during dry season, then a well with a rainy season
overflow (= water collection point) should be built. This is called a combination spring-well.
369
D) Essential Elements of a Spring Protection
A well protected spring has the following indispensable elements:
1. Springbox
It must be durable, impermeable on three sides, and permeable towards the spring.
2. Cover
The cover, preferably from reinforced concrete, must be heavy, lockable, and have a slope to
drain the rainwater.
3. Overflow Pipe
The overflow pipe is installed at the highest water level to prevent building up of pressure
inside the springbox. It must be screened with a non-corroding screen from copper or plastic
to keep animals out. It can serve as air-vent at the same time.
4. Distribution Pipe (= Discharge Pipe = Outlet = Spout)
The distribution pipe supplies the water to the users. It can also lead to a separate storage
tank downhill. If the yield of a spring is low, the distribution pipe can be equipped with a tap to
allow water to collect inside the springbox.
5. Sealing with Puddled Clay
Different parts of the spring protection system have to be sealed with puddled clay. Puddled
clay is clay which is worked while wet into a compact mass that becomes impervious to water
when dry. It is the same type of “mudding” which is used to build a tukul. Puddled clay has to
be smeared in 5 cm thick layers, to be compacted with the feet, and to be well compacted. An
impervious layer must be at least 30 cm thick, i.e. it must be smeared in six layers.
6. Protective Planting
The area around the spring must be planted with a strong type of grass (fibrous grass) to
prevent erosion (= the surroundings from being washed out).
7. Fencing
The spring must be fenced to prevent animals. Preferably, a hedge should be planted for
easier maintenance and cheaper costs.
8. Surface Drainage Ditch (= Diversion Ditch)
A surface drainage ditch must be constructed around the spring to divert all rainwater. It
should be about 8 to 10 m away from the spring-box. It should be lined with gravel or stones
to increase flow and to prevent erosion of the sides.
9. Area Cleanliness
The area around the spring in a radius of 50 to 100 m must be free from latrines and other
sources of pollution.
E) Planning a Spring Protection
For planning a spring protection, consider these steps:
1. Consult the local people where the springs are in the area. Ask which ones stop flowing
during dry season.
370
2. Investigate around the area and check to see if the spring is not in reality a stream
which has gone underground and is reemerging.
3. The springbox should not be built on swampy ground.
4. The springbox should not be threatened by flood or erosion.
5. Check if the water looks clear.
6. Check the flow of the spring. Measure it with buckets (l/min).
7. Check if there are possible sources of contamination nearby.
8. Identify what kind of spring you have (see B) and what type of design to use (see C).
9. Check if the water rights in the area allow the construction of a spring protection.
10. Get or draw a map of the area, including the spring site(s), the nearest houses,
latrines, etc., the distances, the elevations, and important land marks.
F) Constructing a Spring Protection
The construction of the different designs for spring protection shall not be discussed here in
detail. However, some basic principles shall be listed here, valid for all designs:
1. Set the distribution pipe level first before the construction begins. Drive a large wooden
peg into the ground outside the area to be excavated. Never disturb this reference peg.
2. While excavating, take care not to disturb the ground formations. Without care, the flow
of the spring might be deflected into another direction. Careful digging around the eye of
the spring might increase the flow.
3. The foundation of all parts of the spring protection must reach into the impermeable
layer.
4. Dig a temporary drainage channel while building the springbox to be able to work in a
relatively dry area.
G) Maintenance of a Spring Protection
A spring protection needs a small amount of maintenance in order to prevent water
contamination, ensure long life and give optimum service to the users. How water distribution
and maintenance are organised is up to the community (see also social duties of a hand
pump caretaker 8.33). In the following we list only the technical steps of maintaining spring
structures, which should be done regularly, at least once a year.
1. Check if water from the surface is likely to enter the spring and contaminate it.
Surface water is likely to enter the spring
- if the water temperature is higher during the day than at night;
- if the yield increases after a rain;
- if the turbidity increases after a rain.
2. Check if any water is seeping beside or underneath the spring structure. If water seeps out,
seal the leak with clay or concrete.
3. Check the surface drainage ditch. Clean it, remove any obstacles and improve it, if
necessary.
371
4. Check the fence and repair it, if necessary.
5. Check if the springbox and anti-seepage walls are solid or are washed out by erosion. If
there are signs of erosion, fill the holes with earth and gravel, plant grass and improve the
drainage ditches.
6. Clean the springbox from sediments.
7. If there are infiltration trenches, flush them with water through the clean-out pipes.
8. Check if the cover of the springbox is watertight.
9. Check the screening of the pipes and replace it, if necessary.
10. Disinfect the spring once a year (see 8.36).
11. Take periodically samples from the spring and let them be examined in a water laboratory,
if possible.
8.36. Well Disinfection
Hand dug wells are contaminated by workers and equipment during construction.(Urinating
and defaecating in the well during construction are strictly forbidden). Boreholes are
contaminated by equipment and casings. Hand pumps are contaminated by pipes, rods and
tools. Therefore, after completion of a well and after each hand pump maintenance a well
needs to be disinfected in order to provide safe and uncontaminated water to the consumers.
There are different methods to clean the water of a well:
A) Chlorination
Chlorination is a way of chemical disinfection and is the most commonly used form of
disinfection. Basic information about this method is compiled here.
1. Dosage
Different dosages are used. They are indicated in mg/ l or ppm. 1 mg/ l is the same as
mg
and stands for 1 milligram per litre. 1 mg/ l means that there is 1 mg chlorine (the
l
chemical chlorine available for disinfection) in 1 l water. 1 ppm stands for 1 part per million
and means 1 mg chlorine per 1 million mg water, as 1 l water = 1 kg = 1,000 g = 1,000,000
1
mg (see also 5.3/5).
Dosage
30 ppm
5 ppm
3 ppm
0.3 - 1.0 ppm
Description
strong chlorination for disinfecting wells after construction or maintenance.
Not drinkable.
moderate chlorination for disinfecting wells under use or water in the
household. Not drinkable.
dosages above 3 ppm can cause diarrhea.
residual chlorine in drinking water. Drinkable.
Chlorine is available in different forms, as powder or as liquid.
Bleaching powder has 25-35% available chlorine, that means that only 25-35% of the powder
is chlorine and is available for disinfecting the water.
372
Old bleaching powder has become weak and has lost most of its initial chlorine. Therefore,
we assume only 5% available chlorine in it.
High strength calcium hypochlorite has 70% available chlorine; it is more expensive than
bleaching powder and more difficult to get.
Liquid bleach is a chlorine solution, e.g. 5%. sodium hypochlorite. 5% solution means that 5%
of the solution is the chemical, the rest is water. 1 l of a 5% solution contains (as 1 l = 1000
g)
5% of 1,000 g = 50 g chlorine = 50,000 mg chlorine.
Thus a 5% solution is the same as 50,000 mg/ l or 50,000 ppm.
2. Handling Chlorine
Once a container with chlorine is opened, it fairly rapidly looses its initial chlorine content,
especially, if exposed to air, moisture, heat and light. Also, chlorine is very corrosive.
Therefore:
Store chlorine in dry, close, dark, non-rusting containers in a cool place, like
- plastic jerrycan, painted black;
- nylon bag put into a closed tin;
- dark bottle well closed.
During chlorination take into account that the disinfectant may have lost strength and, in this
case, add more.
It is essential to add sufficient chlorine to satisfy the chlorine demand of the water and to have
a little spare chlorine left which is called “free active chlorine” or “residual chlorine”.
The water should be clear (that is without turbidity) before chlorination. Otherwise a higher
dose is needed.
Treat chlorine powder and solution carefully. Do not touch the disinfectant. Never drink a
chlorine solution. It is extremely dangerous because it eats up the stomach inwardly. Mind
your eyes; if chlorine has touched your eye, rinse it with water immediately for 10 minutes.
3. Steps of Chlorination
For chlorinating a well after construction, follow these steps:
a) Calculate the volume of the water in the well (see also 5.6/2):
V = π × r2 × h
Volume (m3) = inside diameter (m) ×
1
inside diameter (m) × 3.14 × depth of the water from
2
the bottom to the water table (m)
373
Example:
SCALE 1:80
h = 4.80 - 3.50 = 1.30 m
r = 1.20 ÷ 2 = 0.60
π = 3.14
V = 0.60 m × 0.60 m × 3.14 × 1.30 m = 1.47 m3
b) Check what kind of disinfectant you have and its percentage of available chlorine.
c) From table 1 (see 8.36/4) find the amount of chlorine that will have to be added to the
volume of water to produce a strong chlorine solution (30 ppm).
d) Dissolve the required amount of the chemical in a bucket of water before adding it to the
well. This solution must have a strong chlorine odour (= smell); otherwise, it has less available
chlorine content than you assumed and you must add more.
e) Pour the solution into the well. It is best to agitate the water to ensure that the chlorine is
evenly mixed. Pump the hand pump a bit until the pipes are filled with chlorine solution.
f) The strong chlorine solution should be left in the well for at least 12 hours and preferably 24
hours; it must be stressed that this strong chlorine solution is not suitable for humans or
animals.
g) After 12 to 24 hours contact time, the strongly chlorinated water should be pumped from
the well until the residual chlorine level is below 1.0 mg per litre of water (with little chlorine
taste). The pumping equipment to be installed on the well can be disinfected by using it to
remove the excess chlorine. Choose a disposal place for the chlorine solution where it will
have as little contact with plants and animal life as possible.
374
TABLE 1 FOR DISINFECTION OF WELLS AFTER CONSTRUCTION
The approximate dosage is 30 mg/ l (= 30 ppm). Do not drink this water after disinfection. Empty the well after 12 to 24 hours contact time until the residual
chlorine is about 0.3 to 1.0 mg/ l (= 0.3 to 1.0 ppm) and the water has only slight chlorine odour and taste. Then you can drink it.
Water
220 l =
1000 l =
1
drum
old (weak)
bleaching powder 5%
132
3
g = 1 salsal
Powders
bleaching powder
25-35%
22 g =
1 tablesp.
2
4
1
m3
600
g = 8 salsal
100 g =
1.5
2
m3
m3
900
1.2
g = 12 salsal
kg
150 g =
200 g =
2.5
m3
1.5
kg
250 g =
3
m3
1.8
kg
300 g =
3.5
m3
2.1
kg
350 g=
4
m3
2.4
kg
400 g =
5
m3
3.0
kg
500 g =
6
m3
3.6
kg
600 g =
2
1
1
3
high strength calciumhypochlorite 70%.
9g=
1 tablespoon
salsal
43 g =
salsal
salsal
65 g =
86 g =
salsal
110 g =
4
salsal
130 g =
2
3
1
5
3
2
6
3
salsal
150 g =
salsal
170 g =
salsal
215 g =
8
salsal
260 g =
2
2
2
3
1
3
3
4
375
3
1
4
5
tablespoons
600 ml =
=8
salsal
7
tablespoons
salsal
900 ml =
1200 ml =
= 12
= 1.2
salsal
1
1
4
1
1
2
3
1
4
2
Liquid
liquid bleach
5%. sodium hypochlorite
132 ml =
3 salsal
l
salsal
1.5
l
salsal
1.8
l
2
salsal
2.1
l
1
4
salsal
2.4
l
3
salsal
3.0
l
1
2
salsal
3.6
l
Water
Powders
bleaching powder
25-35%
700 g =
1 salsal
7
m3
old (weak)
bleaching powder 5%
4.2
kg
8
m3
4.8
kg
800 g =
9
10
m3
m3
5.4
6.0
kg
kg
900 g =
1000 g =
12
15
m3
m3
7.2
9.0
kg
kg
20
m3
12.0
30
40
50
100
m3
m3
m3
m3
18.0
24.0
30.0
60.0
9
3
2
10
3
high strength calciumhypochlorite 70%.
300 g =
4 salsal
salsal
340 g =
salsal
kg
385 g =
430 g =
1. 2
1. 5
kg
kg
520 g =
650 g =
kg
2
kg
860 g =
kg
kg
kg
kg
3
4
5
10
kg
kg
kg
kg
1300 g =
12
1
376
4
Liquid
liquid bleach
5%. sodium hypochlorite
4.2 l
1
2
salsal
4.8
l
5
salsal
salsal
5.4
6.0
l
l
salsal
salsal
7.2
9.0
l
l
salsal
12.0
l
kg
kg
kg
kg
18.0
24.0
30.0
60.0
l
l
l
l
3
5
4
7
2
8
3
1
11
2
1.3
1.7
2.2
4.3
Comparative measurements see Table
2, 8.37/3;
ml = millilitre
l = litre
m3 = cubic
metre
g = gram
}
see
5.3/4
kg
=
kilogram
}
see
5.3/5
4. Further Information
The amount of chlorine in the table was calculated as follows:
for powders:
amount of disinfectant (mg) =
dosage (mg/l = ppm) × quantity of water (l )
1
percentage of available chlorine (%) ×
100
Example:
1 m3 water, 30 mg/ l (= 30 ppm), high strength calcium hypochlorite 70%;
30 mg/l × 1,000 l
≅ 43,000 mg = 43 g
1
70 ×
100
for liquids:
amount of liquid (ml) =
dosage (mg/l = ppm) × quantity of water (l)
percentage of solution × 10
Note that 1 ml of a 5% solution contains, as 1 ml = 1 g:
5% of 1 g = 5% of 1000 mg = 5 × -^ × 1000 mg = 5 × 10 mg (see also 8.36/2)
Example:
1 m3 water, 30 mg/ l (= 30 ppm), liquid bleach 5%;
30 mg/l × 1,000l
= 600 ml
5 × 10
B) Pumping
If no disinfectant is available, clean the well first thoroughly by hand and then pump the well
as much as possible. This will reduce the contamination, but it is not a 100% safe method.
C) Treatment with Sand Filters
Locally made sand filters may be used to treat drinking water. They are simple and provide
clean water, but need maintenance. For further details see the literature, especially No. 44 in
the bibliography.
377
8.37. Water Treatment at Home
It is very important to have safe drinking water in the household. Different methods to treat the
water at home in order to get safe drinking water are discussed here. Choose what is
available and appropriate under the given circumstances.
A) Water from Safe Sources
To get water from a safe source is the best solution and, in this case, no treatment is needed.
Hand dug wells with hand pumps and boreholes can be safe sources if the groundwater is not
polluted and the platform has no cracks. Inquire if the water was tested in a laboratory and is
safe.
However, if you cannot get your drinking water from a safe source, you can treat it with the
following methods.
B) Sedimentation
If the water is of brownish colour and not clear (= turbid), it has a lot of suspended matter.
This is called “turbidity”. Before any further disinfecting, the suspended matter must be
removed. Let the water stand over night until the suspended matter settles. Carefully pour off
the clear water. This will reduce the contamination; therefore, you should do it even if you
cannot treat the water further. But the water is not safe after sedimentation only.
C) Coagulation with Alum
Mix alum (= aluminium sulphate) with the water and let it settle. The particles of the alum will
combine with the suspended matter and form small lumps. The lumps will settle. This process
is called coagulation. Treating water with alum is a clarification process. The higher the
turbidity, the more alum you need. It removes the turbidity and reduces the contamination, but
does not provide safe drinking water.
D) Coagulation with Plants
The seeds of certain trees (e.g. moringa olifera) act like alum when powdered and can be
used for coagulation. For further details see the literature.
E) Pouring Water through Cloth
Pouring water through a clean cloth can reduce the turbidity, but it does not remove the
contamination; it is a pre-treatment method. Wash the cloth after each use.
F) Chlorination
Chlorination is a common and simple form of water treatment in the home. For detailed
information about chlorine see 8.36.
For chlorinating drinking water in the home, follow these steps:
1. Clarify the water by one of the methods mentioned above before chlorination.
2. Determine the quantity of water you want to disinfect:
1 water jerryccan
1 drum
= 20 l
= 220 l
= 0.02 m3
= 0.22 m3
3. Check what kind of disinfectant you have (if possible, from the label of the package) and its
percentage of available chlorine. Commonly available powders are mostly bleaching powder.
378
4. From TABLE 2 on the next page, find the amount of chlorine to be added to the water to
produce a moderate chlorine solution.
5. Dissolve the disinfectant in a cup of water.
6. Pour the solution into the water and stir it well. This initial dose shall produce a 5 ppm
solution; it must have chlorine smell. Otherwise the chlorine has lost its strength and you must
repeat the dosage.
7. Let the water stand for at least 30 minutes. The chlorine reacts with the organic and
inorganic matter present in the water. After 30 minutes, the chlorine concentration ought to be
reduced to less than 1 ppm.
8. After 30 minutes (or more), check for the residual chlorine. The treated water should have a
slight chlorine odour and taste. If not, repeat the dosage (Return to step 3). If the water has
still no chlorine odour, the disinfectant is expired and useless. If the water has too strong a
chlorine taste, allow it to stand for a few hours. Contact with the air removes the taste and
smell of chlorine.
G) Treatment with Iodine
Iodine can be used for disinfecting water. The water must be clear; treatment with iodine is
not suitable for water with a high turbidity.
1. Clarify the water with one of the above methods before treatment with iodine.
2. Pour 2 drops of iodine per litre into the water (e.g. 40 drops per jerrycan and 440 drops per
drum). Double the dose if the water is highly polluted. Stir the water.
3. Let it stand for 30 minutes. Then you can drink.
TABLE 2 FOR DISINFECTION OF DRINKING WATER
The approximate dosage is 5 mg/ l (= 5 ppm). Do not drink the water immediately after
disinfection. After 30 min contact time the residual chlorine should be about 0.3 to 1.0 mg/ l
(= 0.3 to 1.0 ppm). The water should have a slight chlorine odour and taste. Then you can
drink it.
379
Water
20 l =
220 l =
1000 l
=
1
1
1
jerryc.
drum
m3
old (weak)
bleaching powder 5%
2g= 1
teaspoon
tablespoons
22 g =
1
2
100 g
=
2
1
1
3
1
1.2
m3
120 g
=
1.5
m3
150 g
=
2
m3
200 g
=
2.5
m3
250 g
=
3
m3
300 g
=
4
5
m3
m3
0.3
3
salsal
14
17
2
salsal
21
2
3
1
3
3
salsal
4
2
Liquid
liquid bleach
5% sodium hypochlorite
2 ml = 1
teaspoon
tablesp.
22 ml =
1
2
g= 1
1
2
teaspoons
100 ml
=
2
1
1
3
tablespoon
120 ml
=
1
1
3
1
g= 1
2
tablespoons
150 ml
=
2
salsal
tablespoons
200 ml
=
2
3
1
3
3
salsal
4
salsal
7
g=
2
1
2
1
3
29
1
g= 3
3
tablespoons
11
tablespoons
14
salsal
36
tablespoons
18
g=2
tablespoons
250 ml
=
salsal
43
21
g=
tablespoons
300 ml
=
tablespoons
400 ml
=
5
1
3
salsal
tablespoons
500 ml
=
6
2
3
salsal
1
3
salsal
500 g
=
6
2
3
salsal
kg
57
71
g= 2
g=4
g= 4
3
4
tablespoons
g= 6
1
3
tablespoons
g=1
salsal
9
5
g=2
tablespoons
tablespoons
400 g
=
1
2
high strength calcium
hypochlorite 70%
0.1
g
1.6
1 teaspoon
g=
2
salsal
1
2
Powders
bleaching powder
25-35%
g
g=1
teaspoon
g= 1
1
2
3
29
g=
1
3
3
g=8
tablespoons
=1
salsal
380
36
g=4
=
1
2
salsal
1
2
2
1
2
salsal
salsal
l
Comparative Measurements(approximately)
1 teaspoon, flat
1 tablespoon, flat
1 salsal tin = tin for tomato
paste
1 teaspoon
1 tablespoon
1 salsal tin = tin for tomato
paste
= 3 g chlorine powder
= 9 g chlorine powder
= 75 g chlorine powder
= 8 tablespoons chlorine powder
= 3 ml
= 9 ml
= 75 ml
= 8 tablespoons
ml = millilitre; l = litre; m3 = cubic metre (see 5.3/4); g = gram; kg = kilogram (see 5.3/5)
H) Boiling
Boiling destroys all forms of disease organisms in water. However, boiling requires a lot of
firewood or other fuels and is very expensive.
Bring the water to a rolling boil; the water must be bubbling rapidly. Let it boil for 2-3 minutes.
Store the water in the same container in which it was boiled to prevent new contamination.
To boil a large quantity of water for many people, the boiler can be built from a drum (see
drawing):
I) Filtering with Sand Filter
Household sand filters made from locally available materials can be used for cleaning the
water.
Sand filters where the sand is not constantly covered by water clarify the water, but do not
remove the bacteria. Sand filters where the sand is constantly covered by water remove most
of the bacteria.
For details see No. 44 in the bibliography and other literature.
A household sand filter is shown on the drawings next page. See also 6.1/22.
381
Household Sand Filter
J) Filtering with Commercial Filters
Commercial filters with filter candles made from fired ceramics provide water free from
bacteria, if maintained according to the instructions. They are relatively expensive and can
filter only a limited amount of water per day.
382
K) Storage
Five or six days water storage is enough to reduce the level of bacteria enough so that people
can safely drink the water. If the water quality is poor, increase the length of storage.
Use two barrels with taps and covers. Fill both barrels and empty one completely before using
water from the second. When use from the second barrel begins, refill the first barrel. Each
time, clean the barrels carefully. Use the water from the barrels only for cooking and drinking.
L) Heating
Expose jerrycans of water to the sun for one day. The water will be heated to 50-60°C. This
will reduce organic contamination, but not remove it completely. See in the bibliography 46,
July 1986.
M) Restriction of the Use of Safe Water
Restrict the use of the available safe water to basic needs like drinking, cooking, washing
dishes, brushing the teeth. Use different water for bathing and washing the laundry.
ONE JERRYCAN = 20 LITRES
ONE SHORT-CALL = 20 LITRES
DO NOT WASTE DRINKING WATER!
383
See also 8.29/5 and 9.8/2.
8.38. Handling Water at Home
A) Possible Ways of Contamination of Water from a Clean Source
Even if water is taken from a clean source which is safe for human consumption, we may
afterwards still experience diseases. The reasons may be that the water is contaminated
- during collection and delivery to the home,
- during storage and use in the home.
This can happen in the following ways:
1. During Collection and Delivery to the House
- The container for fetching the water can be contaminated, e.g.
* if it is not kept clean or has holes,
* if people use their hands or other dirty items as a funnel to direct the water into the
container,
* if people wash hands and face, etc., while filling the container at the same time,
* if the container is used for fetching drinking water from the borehole and then the same
container is used for water for other purposes from an unsafe source,
* if the container is left open at home and flies, cockroaches and other animals have
access to it.
- The container is left without cover when fetching: animals may drink; the hand of the one
carrying may go into the water while lifting and carrying the container.
- The cover used is not clean, e.g. the lid of the jerrycan is put on the ground or leaves are
used as cover for a bucket or claypot.
- The water is put from the pump into an open barrel and then taken to the house by jerrycan.
The wind can blow dirt into the barrel and the jerrycan will dirty the water when dipped into it
for filling after standing on the ground.
2. During Storage and Use in the House (see also 9.5/3)
- The container for storage is contaminated, e.g.
* It is not cleaned regularly.
* Members of the family do not wash their hands after going to the latrine. Their hands
remain dirty. The person is thirsty and takes water from the pot with a cup, but is not
careful and reaches with their hand into the water. The germs enter the water and infect
others drinking later on.
* The pot has no lid or the lid does not close properly or is not relaced after each use. Dust
and dirt can enter the pot; flies, cockroaches and other animals can contaminate the water,
especially, if it is placed directly on the ground.
- The cup used for taking water from the pot is contaminated, e.g.
384
* It is not washed regularly.
* People use the same cup for dipping and for drinking. Saliva of a sick person enters the
water and brings germs to it. Others drinking later get infected.
* Many people use the same cup and infect the water and each other.
B) Possible Ways to Avoid Contamination
1. Generally
Never touch drinking water with your hands.
2. Container for Transport
- Clean your hands before fetching water.
- Clean the container before fetching water.
- Always use a closed container with a clean and fitting lid.
- Use separate containers for drinking water and other water. Do not use the container for
drinking water for any other purpose. If you have only one container, wash it thoroughly
with sand, soap and hot water and rinse it afterwards, each time before you fetch water for
drinking.
3. Container for Storage
- Equip the pot with a tight lid and tap.
- Remove water from the pot only through the tap.
- If there is no tap, teach everybody in the home how to take water carefully not touching it
with the hands, to pour water into another cup for drinking, and to replace the lid.
- Clean the pot regularly and do not keep water for more than 2 weeks.
- Put the pot on a stand to prevent algae and fungi growing into the pot, animals having
access to it and small children touching the water.
- Insist that everybody in the home washes his/her hands with soap after going to the
latrine.
4. Container for Drinking
- Clean the cups regularly.
- Ensure that everybody uses his/her own cup, if possible; at least ensure that somebody
sick uses a separate cup for drinking.
- Never use the same container for dipping and drinking.
- If there is no tap, use a container with a long handle for dipping, stored inside the pot,
below its cover.
C) How to Equip a Claypot with Tap and Lid
One possibility to prevent contamination of the water in the home is to equip the pot for
storage with a tap and a lid. In the following, it is described how that can be done.
385
1. Instructions How to Fix a Tap
a) Materials and Tools Needed
Quant
1
Item
claypot (can be an old one, but it should
not have any cracks)
1
1
“ tap with joining piece (should be
2
2
joined together in the shop to see
whether it fits properly)
tablespoons of cement
1
for drilling:
1
1
reinforcement rod Ø 6 mm, 25 cm long
(can be sharpened by cutting with a bolt
cutter or with a stone)
or
6” nail
or
hand-operated
stone bits
drilling
machine
1
rasp (if available)
1
big bowl for soaking the pot
1
1
small bowl
table spoon
2
nylon bags
cloth or paper
sand and water (not salty)
with
386
Drawing
b) Step-by-Step Procedures
No
1
Step
Mark the place you want to fix the tap on
the pot. Soak the pot in water and also
pour water into the pot. The location of the
tap needs to be well soaked.
2
The tap should be connected with a
joining piece of pipe. This should be done
in the shop where you buy the tap. Hold
the tap with the joining piece against the
pot at its future location and draw a circle
around it. The location should be not too
low or too high on the pot.
3
Make a big hole for the tap by making first
several small ones. Scratch the pot
carefully with the 6” nail or reinforcement
in the way you stir food until you have
made a hole, or drill with a hand-operated
drilling machine with a bit for stone. Never
use a hammer. Smoothen the edge of the
hole with a rasp; it shall be just big
enough to push the tap in.
4
Close both sides of the tap with a piece of
cloth or paper.
5
Choose a place where the pot can remain
unmoved for 2-3 weeks. Put sand on the
ground and position the pot in it so that
the opening for the tap is on the top. The
tap shall be in vertical direction.
6
Mix in a small bowl 2 tablespoons of
cement with very, very little water. The
mixture must be very stiff, like asida (=
ugali).
387
Drawing
No
7
Step
Place the tap into the opening in such a
way that it is horizontal in the final
position. Make the place wet. Smear the
cement mortar around the joining pipe
from inside and outside. The mortar shall
be as thick as a finger at the tap and
smooth on the edge.
8
9
Do not move the pot at all.
Wait until the mortar is a bit hard. Then
cover it with wet sand and a nylon. Pour
some water into the pot and close the
mouth of the pot with a nylon bag.
10
Keep the sand wet continuously for five
days. This is most important.
After one week, the pot can be carefully
moved and the lid can be manufactured.
After a second week or later, the pot can
be used.
Remove the cloth or paper from the tap
and clean the pot carefully before use.
11
12
Drawing
2. Instruction How to Make a Lid
a) Materials and Tools Needed
Quant
1
Item
Drawing
claypot
1
handle, bent into shape from
reinforcement rod or any other scrap
metal.
1
support piece, from hard carton,
plywood, or an old plate
2
2
nylon bags
cups of sand
388
Quant
1
Item
cup of cement water
(should not be salty)
Drawing
1
sieve (used for flour) or a piece of
mosquito wire
1
1
bowl
tablespoon
1
6” nail (for scratching a mark on the
pot)
b) Step-by-Step Procedures
No
1
Step
Scratch two marks into the edge of the pot.
2
Position the pot vertically in sand and pour
some water into the pot.
3
Cut a support for casting the lid from carton
paper or plywood, or use any fitting plate.
Place it into the mouth of the pot) it should
not fall in, but leave an edge of the pot free.
4
Bend a piece of reinforcement into the shape
of the handle.
389
Drawing
No
5
Step
Place a nylon bag on top of the supporting
piece on the mouth of the pot, hanging over
the edge of the pot.
6
Sieve sand. Mix 2 cups of sand with 1 cup of
cement and a little water. The mortar should
be very stiff like asida.
7
Smear the mortar on the nylon as thick as
your smallest finger.
Place the handle on top.
8
9
Finish the lid with mortar. When completed,
it should be as thick as two fingers. Smear
the mortar tight on the edges of the pot. The
edge of the lid shall not be too thin.
Smoothen the surface.
10
Scratch two marks on the lid, matching the
marks on the pot.
Wait until the mortar is a bit hard. Then put
sand, soaked in water, on top of the lid.
Cover it tightly with a nylon bag and and tie
the bag around the mouth of the pot.
11
12
Do not remove sand and nylon bag for one
week. Afterwards remove the sand, nylon
bags and support Clean the lid and the pot
thoroughly.
The pot is now ready for use.
390
Drawing
8.39. Health Education about Water/Operating Instruction for Wells
A) Health Education about Water
People need to be made aware about the facts concerning water and health in order to
improve their situation and change wrong habits. Therefore, the aim of the health education
about water in the project is
- to inform people about the importance of clean water and the connection with sanitation;
- to make people understand the importance of keeping the well properly and how to use it
in a good way;
- to make people understand the importance of maintenance and continuous care for the
well.
B) Connection of Water and Health
A change in the health situation can only happen if all people use good water and sanitation
facilities and use them properly.
Water supply and sanitation are very closely connected; improvement can only happen if
none of them is neglected. In this chapter, we deal with the water side, the sanitation side is
mentioned in 9.5, 9.6, 9.21, 9.22.
Water must be sufficient, clean and safe in order to contribute to reducing disease, not only
for drinking and cooking, but also for
- bathing, hand-washing and cleaning the teeth;
- cleaning vegetables, fruit and kitchen utensils;
- washing the laundry;
- watering animals(see also 8.5 and 8.6).
The problem is that one cannot see or easily know whether water is really clean and safe.
Water which looks clean can still carry disease, and other water which may have a salty taste
and not be liked by the people may be safe.
In order to have water which is really clean and safe, that means it contains nothing which
can cause disease, we have to prevent contamination of water which we know is safe, that is
391
normally groundwater. Contamination needs to be prevented
- at the water source,
- during collection and delivery
- during storage and use in the household
}
}
see 8.38
see 8.38
Water can be polluted at the source by
How to prevent/cure it
chemicals, like fuels, DDT, etc. washed into
the ground by rain
- Do not use dangerous chemicals where
water is used for human consumption. See
9.13/3; 9.16/2
- There is no cure.
- Keep “safe” distances (at least 50m) between
latrines and water source. See 4.15/6; 8.12/1;
9.8/3.
- Never have a latrine reach into the
groundwater. See 9.8/3.
- Cure for germs: chlorination.(8.36)
- No cure for nitrates/nitrites.
poor sanitation facilities or wrongly
constructed latrines or WCs and septic
tanks, through germs and nitrates/nitrites
Dirty water around the well, see- ping into it
(surplus water from the pump or rainwater)
dirt or small animals falling into the well
- Care for a proper platform, big enough,
without cracks, and with a drainage channel
and soak-away pit. See 8.19.
- Care for a hedge or fence not to let animals
come near and dirty the place.
- Keep the area around the well dry and clean
and without rubbish.
- Do not wash laundry near the well but
provide a place for that at a distance.
- Care that the well cover is closing properly.
See 8.20/3.
- Care that there are no cracks in the platform.
See 8.33/1.
C) Operating Instruction for a Well
In the project, handing over of a well to a community is used as a chance for health
education. This is reinforced by regular follow up visits. The operating instruction takes place
at the well site and is based on the knowledge people already have on the subject, e.g.
- It is bad to drink dirty water.
- Little rain will give little water in the well.
- If the well is misused, there will be no other nearby source of good water.
- If the well is open, it is dangerous for children and animals.
- If a pump breaks down, there will be no water.
The topics covered are the water cycle, keeping the well and its surroundings clean, taking
care of the hand pump, and using it properly. The methods used are practical demonstration,
drama and posters together with explanations. For hand pump caretakers this topics will be
covered, together with the duties and technical information, in a small seminar.
The following posters are used for operating instruction of a well.
392
393
394
395
10. Appendix
10.1. List of Abbreviations
A/...
Adm.
BH
ca.
CD
CDO
CL
c/o
e.g.
etc.
...f
...ff
GW
HP
ID
i.e.
L
Log
£S...m/ms
OD
pc
pcs
PMT
San
SCC
W
WC
WS
WT
Assistant...
Administration
Borehole
circa = about
Community Development
Community Development Officer
Compost Latrine
care of
exempli gratia = for example
et cetera = and so on
... and the following page
... and the following pages
Groundwater
Hand Pump
Inside Diameter
id est = that is
Latrine
Logistics
Sudanese Pounds... milliemes
Outside Diameter
Piece
Pieces
Project Management Team
Sanitation
Sudan Council of Churches
Well
Water Closet
Water Supply
Water Table
Abbreviations for Measurements see 5.3
Abbreviations in Mathematics see 5.4 and 5.7
10.4. List of Illustrations (from literature)
References to illustrations page numbers and authors given in the table below reflect the
printed version. In order to have the exact correspondence please consult the PDF version of
this file.
All illustrations not mentioned in the following list as well as the adaptions were made by
Márta Guóth-Gumberger.
Section
1
2
3
4
Illustration Page No.
1.3/2; 1.6/6; 1.7/1
2.4/4; 2.7/2; 2.8/2; 2.12/1
2.18/1-4; 2.18/6
3.1/2; 3.3/2; 3.6/1; 3.7/1; 3.8/1; 3.9/3
4.8/1-3; 4.19/3
4.4/2; 4.8/5; 4.12/1f; 4.14/3-6; 4.18/4f
396
Taken from/Made by
Ben Hakim
Ben Hakim
bibliography No. 12; 27
Ben Hakim
Ben Hakim
Mike Gogonya
Section
6
Illustration Page No.
4.1/4
4.6/1
4.6/3 (below)
4.6/3 (top); 4.8 (adapted); 4.12
(adapted); 4.14 (adapted); 4.16/2;
4.18 (adapted); 4.23/3 (below); 4.27
(partly adapted)
6.4/8; 6.6/14
6.3 (partly adapted)
6.1/20
7
8
9
0 to 9
6.1/21
6.1/22 (bottom); 6.6/2 (adapted);
6.6/6; 6.7 (adapted)
7.2/2; 7.3/1; 7.6/3; 7.8/3; 7.12/3
8.7/5; 8.9/2; 8.37/7 (left); 8.39/3-7
8.24/24 (adapted)
8.24/29
8.24/30
8.24/7-30 (partly adapted); 8.30
(adapted); 8.35 (adapted); 8.37/4,6
9.9/2; 9.19/2; 9.20/5; 9.21/2
9.6/1,2(bottom), 3-10; 9.17/2-32
9.1/2; 9.2/2; 9.2/3; 9.6/2 (top),4
(bottom)
9.3/1; 9.3/2; 9.3/5f; 9.5/2f (adapted);
9.6(adapted);
9.12/2;
9.12/3
(adapted); 9.12/4 (top, adapted);
9.20/1-4; 9.11/2; 9.22/3
drawings title pages
Taken from/Made by
The Guardian Weekly
The International Women’s Tribune
Sueddeutsche Zeitung
bibliography No. 20; 37; 48
Ben Hakim
catalogue 1986, Luna AB Sweden, and
catalogue 1983, Mittermeyer, W-Germany
manual diaphragm pump, Van Reekum
Materials, Netherlands
manual Hatz Generator, West Germany
bibliography No. 6a; 8; 44
Ben Hakim
Ben Hakim
leaflet, Mono Pump
leaflet, Homa Pump
leaflet, Jet pump
bibliography No. 18; 21; 22; 44; 46
Ben Hakim
Mike Gogonya
Stephen Hakim
bibliography No. 6; 23; 34; 48; 49
Ben Hakim
10.5. Bibliography
Literature used and recommended for further studies:
1. A Growing Problem, by David Bull; OXFAM, 2 74 Banbury Road, Oxford OX 2 7 DZ,
England
2. A Manual And Resource Book For Popular Participation Training, 4 Vol., UN-Publications
ST/ESA/66 Vol. I-IV; UN Publications, 1211 Geneva, Switzerland
3. A Manual For Group Facilitators, by The Centre for Conflict Resolution; The Centre for
Conflict Resolution, 731 State Street, Madison, Wisconsin 53703, USA
4. African Churches And People’s Development, ccpd-document No. 4; WCC, P.O. Box 66,
1211 Geneva 20, Switzerland
5. Appropriate Building Materials, by Roland Stulz; SKAT, Varnbuelstr. 14, 9000 St. Gallen,
Switzerland
6. Biology, by Soper/Smith; MacMillan Publishers
6a. Brickwork For Apprentices, by J.C. Hodge; Edward Arnold
7. Bridging The Gap, by Save The Children; Save the Children, 54 Wilton Road, Westport,
Conn. 06880, USA
397
8. Building Science And Materials, by John Elliot; MacMillan Publishers
9. Communicable Diseases, by Eshuis/Manschot; AMREF, P.O. Box 30125, Nairobi, Kenya
10. Communication, by C.S. Deverell; Gee & Co. Publishers
11. Communication Skills For Rural Development, by McDonald/Hearle; Evans Brothers
Limited
12. Communications Guide for Extension Workers, by RSCTU/UNICEF; UNICEF, Eastern
Africa Regional Office, P.O. Box 44145, Nairobi, Kenya
13. Community Development Workers Training Series, 7 volumes, by UNICEF; address see
12.
14. Development/Seeds of Change, diverse issues; SID, Palazzo della Civilta del Lavoro,
Roma 00144, Italy
15. Guidelines For Development, by CCIA; Christian Conference of Asia, 480 Lorong 2, Toa
Payoh, Singapore 1231
16. Handbook For Development Workers Overseas, by Glynn Roberts; Returned Volonteer
Action, 1 Amwell Street, London EC 1 R 1 UL, England
17. Hand Dug Wells And Their Construction, by Watts/Wood; ITDG Publications, 9 King
Street, London WC 2 E 8 HN, England
18. Handpumps, by Eugene Mc Junkin; IRC, P.O. Box 5500, 2280 HM Rijswijk, Netherlands
19. Handpump Maintenance In The Context Of Community Well Projects, by Arnold Pacey;
ITDG Publications, address see 17
20. Helping Health Workers Learn, by David Werner/Bill Bower; The Hesperian Foundation,
P.O. Box 1692, Palo Alto, CA 94302, USA
21. How To Protect A Water Source And Why?, by Rogers/Kokole; OXFAM/UNHCR, South
Sudan Water Team, Juba
22. India Mark II Handpump Installation Manual; Richardson & Cruddas, 23 Rajaji Salai,
Madras 600001, India
23. Insecticides, by The Ross Institute; The Ross Institute, Keppel Street, London WC 1 E 7
HT, England
24. Learning From The Rural Poor, by Volken/Kumar/Kathathara; Indian Social Institute, Lodi
Road, New Delhi 11003, India
25. Making The Links, Guidelines For Hygiene Education In Community Water Supply And
Sanitation, by IRC; IRC, address see 18.
26. Maths For Living, by W.D. Wright; James Nisbet
27. Navamaga, Training Activities For Group Building, Health And Income Generation;
Overseas Education Fund, 2101 L Street NW, Suite 916, Washington DC 2003 7, USA
28. Notes For Draughtsmen, by Neil Orton; Mac Donald
29. Ordinary Level Mathematics, by F.G.J. Norton; Heinemann
398
30. Organisational Techniques; Overseas Education Fund, address see 27.
31. People In Development, by John Staley; SEARCH, 256 First Block, Jayanagar, Bangalore
560011, India
32. People’s Technologies and People’s Participation, by Pascal de Pury; WCC, address see
4.
33. Sanitation And Disease, by Feachem/Bradley/Carelick/Mara; John Wiley
34. Sanitation Without Water, by Uno Wimblad/Wen Kilama; Mac Millan Publishers
35. Shallow Wells, by DHV; DHV Consulting Engineers, P.O. Box 85, Amersfoort,
Netherlands
36. Small Excreta Disposal Systems, by Feachem/Cairncross; The Ross Institute, address
see 23.
37. Teaching And Learning With Visual Aids; Educational Materials Unit, Program for
International Training in Health, School of Medicine, University of North Carolina, Chapel Hill,
North Carolina, USA
38. Technical Health Training Manual, 2 volumes; Peace Corps, Information Collection and
Exchange, 806 Connecticut Avenue NW, Washington DC 20525, USA
39. The Expanded Programme On Immunization, Health Education Trainers’ Manual For
Extension Workers In Sudan; UNICEF, Juba, Sudan
40. The Programmer’s Tool Kit; Overseas Education Fund, address see 27.
41. The Role And Training Of Development Activists, by Khamla Basin; FFHS/AD, FAO, 55
Max Mueller Marg, New Delhi 110003, India
42. Visual Aids; Peace Corps, address see 38.
43. WASH Technical Reports; WASH, 1611 N Kent Street, Room 1002, Arlington, VA 22209,
USA
44. Water For The World Series; US-AID, Development Information Centre, Washington DC
20523, USA
45. Water Sources And Their Protection, by Rogers/Kokole; OXFAM/UNHCR, Southern
Sudan Water Team, Juba
46. Waterlines, diverse issues; ITDG Publications, address see 17.
47. Well Construction, by Richard E. Brush; Peace Corps, address see 38.
48. Where There Is No Doctor, by David Werner; TALC, P.O. Box 49, St. Albans, Herts., AL 1
4 AX, England
49. World Bank Technical Papers And Technical Notes Series, Water Supply And Sanitation;
The World Bank, 1818 H Street NW, Washington DC 20433, USA
399
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