Download version 0.1 of EM 1110-2-2607 Planning and Designs of Navigation Dams.pdf

Download version 0.1 of EM 1110-2-2607 Planning and Designs of Navigation Dams.pdf
Department of the Army
EM 1110-2-2607
U.S. Army Corps of Engineers
Engineer Manual
Washington, DC 20314-1000
Engineering and Design
Distribution Restriction Statement
Approved for public release; distribution is
31 July 1995
EM 1110-2-2607
31 July 1995
US Army Corps
of Engineers
Planning and Design
of Navigation Dams
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U.S. Army Corps of Engineers
Washington, DC 20314-1000
No. 1110-2-2607
EM 1110-2-2607
31 July 1995
Engineering and Design
1. Purpose. This manual is issued for guidance of individuals and elements within the Corps of
Engineers engaged in the structural planning, layout, and design of navigation dams for civil works
projects. The structural design of gates is not covered in this manual.
2. Applicability. This manual applies to all HQUSACE elements, major subordinate commands,
districts, laboratories, and field operating activities (FOA) having responsibilities for the design and
construction of civil works projects.
Colonel, Corps of Engineers
Chief of Staff
This manual rescinds EM 1110-2-2607, dated 1 July 1958.
U.S. Army Corps of Engineers
Washington, DC 20314-1000
EM 1110-2-2607
No. 1110-2-2607
31 July 1995
Engineering and Design
Table of Contents
Chapter 1
Purpose . . . .
Applicability .
References . .
Scope . . . . . .
Rescission . . .
Chapter 2
General Considerations
for Project Planning
General . . . . . . . . . . . . . . . . . . . . .
Project Team . . . . . . . . . . . . . . . . .
Project Formulation
and Development Processes . . . . .
Legal Environment . . . . . . . . . . . . .
Project Components and General
Feature Requirements . . . . . . . . . .
Examples of Navigation Projects and
Components of Dams . . . . . . . . . .
Existing Conditions . . . . . . . . . . . .
Navigation and Pool Operational
Considerations . . . . . . . . . . . . . . .
Hydraulic Design Considerations . . .
Model Studies . . . . . . . . . . . . . . . .
Miscellaneous Engineering
Considerations . . . . . . . . . . . . . . .
Cofferdams and Other Temporary
Construction Requirements . . . . . .
Environmental and Aesthetic
Considerations . . . . . . . . . . . . . . .
Real Estate Considerations . . . . . . .
Site Selection . . . . . . . . . . . . . . . .
Chapter 3
Access and Support Facilities
General . . . . . . . . . . . . . . . . . . . .
Access to Dam Site . . . . . . . . . . .
Pedestrian Access . . . . . . . . . . . .
Elevators, Stairways,
and Ladders . . . . . . . . . . . . . . .
Equipment Access . . . . . . . . . . . .
Operations and Maintenance
Buildings . . . . . . . . . . . . . . . . .
Control Houses and Operating
Platforms . . . . . . . . . . . . . . . . .
Control Rooms for Remote Lock
and Dam Operation . . . . . . . . . .
Storage Facilities for Protection
of Equipment . . . . . . . . . . . . . .
. . . . . 3-1
. . . . . 3-2
. . . . . 3-3
. . . . . 3-4
. . . . . 3-5
. . . . . 3-6
. . . . . 3-7
. . . . . 3-8
. . . . . 3-9
. . 2-1
. . 2-2
. . 2-3
. . 2-4
. . 2-5
. . 2-6
. . 2-7
. . 2-8
. . 2-9
. . 2-10
. . 2-11
. . 2-12
Chapter 4
Nonnavigation Considerations
General . . . . . . . . . . . . . . . . . . . .
Effect on Floods . . . . . . . . . . . . .
Effect on Drainage . . . . . . . . . . . .
Water Quality . . . . . . . . . . . . . . .
Water Supply . . . . . . . . . . . . . . .
Mosquito Control . . . . . . . . . . . . .
Environmental . . . . . . . . . . . . . . .
Recreation . . . . . . . . . . . . . . . . . .
Hydropower . . . . . . . . . . . . . . . .
Zebra Mussels . . . . . . . . . . . . . . .
. . 2-13
. . 2-14
. . 2-15
Chapter 5
Types of Navigation Dam Structures
General . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
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31 Jul 95
Gated Nonnavigable Spillway . . .
Gated Navigable Spillway . . . . . .
Fixed Crest . . . . . . . . . . . . . . . .
Piers . . . . . . . . . . . . . . . . . . . .
Miscellaneous Structural Features
Special Design Considerations . . .
Chapter 6
Maintenance and Emergency
Closure Facilities
Maintenance and Emergency
Closure . . . . . . . . . . . . . . . . . . .
Maintenance of Gated Nonnavigable
Spillway Structures . . . . . . . . . . .
Emergency Closure of Gated,
Nonnavigable Spillway Structures .
Maintenance of Gated,
Navigable Spillways . . . . . . . . . . .
Emergency Closure of a Gated,
Navigable Spillway . . . . . . . . . . .
Maintenance and Emergency Closure
of a Fixed-Crest Spillway . . . . . . .
Floating Plant . . . . . . . . . . . . . . . .
Galleries, Adits, and Openings . . . .
Line Loads . . . . . . . . .
Ice and Debris . . . . . . .
Wave Loads . . . . . . . .
Wind Loads . . . . . . . .
Gate Loads . . . . . . . . .
Bridge Loads . . . . . . . .
Crane Loads . . . . . . . .
Bulkhead Loads . . . . . .
Sheet Pile Cutoff Loads
Monolith Joint Loads . .
Superstructure Loads . .
Thermal Loads . . . . . .
. . 6-1
. . 6-2
. . 6-3
. . 6-4
. . 6-5
. . 6-6
. . 6-7
. . 6-8
Chapter 7
Seepage Control Measures and Features
General . . . . . . . . . . . . . . . . . . . . . . . 7-1
Foundation Grouting and Drainage . . . . 7-2
Impervious Cutoff Walls
(Trenches) . . . . . . . . . . . . . . . . . . . 7-3
Concrete Cutoff Walls . . . . . . . . . . . . 7-4
Sheet Pile Cutoff Walls . . . . . . . . . . . 7-5
Upstream Impervious Blanket . . . . . . . 7-6
Chapter 8
Channel Protection
General . . . . . . . . . . . . . .
Erodible Slopes and Stream
Typical Materials . . . . . . .
Dikes . . . . . . . . . . . . . . .
Upstream Channel . . . . . .
Downstream Channel . . . .
Chapter 9
General . . . . . . . . . . .
Construction Loads . .
Lateral Earth Loads . .
Hydrostatic . . . . . . . .
Earthquake or Seismic
Tow Impact . . . . . . .
Chapter 10
Design Criteria
Applicability and Deviations
Load Cases . . . . . . . . . . . .
Earth and Rock Foundations
Internal Stability . . . . . . . .
Uplift and Flotation . . . . . .
Pile Criteria . . . . . . . . . . .
Chapter 11
Analysis and Design
General . . . . . . . . . . . . . . . . . . . . . . . . . 11-1
Structural Analysis . . . . . . . . . . . . . . . . . 11-2
Foundation Design and Soil/Structure
Interaction . . . . . . . . . . . . . . . . . . . . . 11-3
Chapter 12
Concrete Design
General . . . . . . . . . . . . . . . . . . . .
Nonlinear Incremental Structural
Analyses . . . . . . . . . . . . . . . . .
Parameters Affecting Cracking
in Concrete . . . . . . . . . . . . . . . .
Concrete Quality for Dam Spillway
and Stilling Basin . . . . . . . . . . .
Second Placement Concrete . . . . .
Chapter 13
Design of Other Items
Galleries . . . . . . . . . . . . . . . . .
Machinery Platforms . . . . . . . .
Machinery Houses . . . . . . . . . .
Line Hooks. . . . . . . . . . . . . . .
Check Posts . . . . . . . . . . . . . .
Deadman Anchorage for Floating
Plant . . . . . . . . . . . . . . . . . .
Ladders and Stairs . . . . . . . . . .
Access to Trunnion Area and
Bulkhead Slots . . . . . . . . . . .
. . . . . 12-1
. . . . . 12-2
. . . . . 12-3
. . . . . 12-4
. . . . . 12-5
. . . . . . . 13-6
. . . . . . . 13-7
. . . . . . . 13-8
EM 1110-2-2607
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Corner Protection . . . . . . .
Handrail and Guardrail . . .
Parapet Walls . . . . . . . . .
Grating . . . . . . . . . . . . . .
Service Bridges . . . . . . . .
Structural Instrumentation .
Warning Signs . . . . . . . . .
Embedded Metals . . . . . .
Mechanical and Electrical
Features . . . . . . . . . . . .
Catwalks . . . . . . . . . . . . .
Dam Lighting . . . . . . . . .
Lightning Arrestor System
Cathodic Protection . . . . .
Surveillance Systems . . . .
Waterstops . . . . . . . . . . . . . . . . . . . . . . 13-23
Joint Materials . . . . . . . . . . . . . . . . . . . . 13-24
Plates 1-21
Appendix A
Appendix B
Design and Construction Planning
Appendix C
Lessons Learned - Case Histories
EM 1110-2-2607
31 Jul 95
Chapter 1
1-1. Purpose
This manual is issued for guidance of individuals and
elements within the Corps of Engineers engaged in the
structural planning, layout, and design of navigation dams
for civil works projects. The structural design of gates is
not covered in this manual.
1-2. Applicability
This manual applies to all HQUSACE elements, major
subordinate commands, districts, laboratories, and field
operating activities (FOA) having responsibilities for the
design and construction of civil works projects.
1-3. References
Required and
Appendix A.
features. The appurtenant features include embankments,
dam piers, stilling basins, training walls, separation walls,
galleries, sills, service bridges, and machinery houses.
This manual is structured so that Chapters 2 through 4
contain layout and planning information; Chapter 5 provides detailed descriptions of types of dam structures;
Chapter 6 discusses maintenance and emergency closure
facilities; Chapter 7 discusses appurtenant seepage control
features; Chapter 8 discusses appurtenant channel protection features; Chapters 9 through 11 present detailed
requirements for stability and structural analysis and
design; Chapter 12 discusses concrete and joint materials,
waterstops, etc.; and Chapter 13 discusses design consideration for miscellaneous dam features. Appendix A
covers references; Appendix B contains a design check
list; and Appendix C describes lessons learned from case
1-5. Supersession
This EM supersedes EM 1110-2-2607, dated 1 July 1958.
1-4. Scope
This manual provides guidance for the planning and
design of navigation dams and appurtenant structural
EM 1110-2-2607
31 Jul 95
Chapter 2
General Considerations for Project
2-1. General
This chapter provides an overview of the engineering,
policy, and planning guidance applicable to developing a
project plan for navigation improvements associated with
the planning, design, construction, and major rehabilitation
of navigation dams. Although there are a number of
similarities among low-, medium-, and high-head lock and
dam projects, care should be taken in use of this manual
to ensure that guidance which applies only to low-head
projects is not misconstrued as applicable to high-head
projects. Because a navigation dam is usually planned
concurrently with a companion navigation lock, the planning effort usually considers both types of navigational
structures in the same studies. Therefore, the intent is for
EM 1110-2-2602 to be used in conjunction with this
manual as that manual covers many of the items mentioned below in more detail.
2-2. Project Team
The planning, engineering layout, and design of navigation dams as part of the overall development of a project
plan for navigation projects comprise a complex, multidisciplinary planning and engineering effort. This effort
involves the contributions from many public and private
interests including local, state, and federal agencies; planners; design, operations, and construction engineers; architects; and natural habitat biologists. The team will either
include or derive considerable input from budgetary, legal,
and contracting specialists.
2-3. Project Formulation and Development
The Corps of Engineers’ involvement in these processes
for navigation dams, i.e., civil works reconnaissance studies, feasibility reports, and preconstruction engineering
and design (PED), is very similar to that for navigation
locks, as covered in EM 1110-2-2602. Also, guidance for
developing cost estimates discussed in that manual is
applicable to the navigation dam. Since completion of the
PED work is frequently scheduled to be at different times
for the lock and the dam due to limited resources, it is
important to carefully coordinate the details for these
structural entities so that a quality end product is
completed on time and within budget.
2-4. Legal Environment
Legal issues which must be considered in project development include, but are not limited to, method of funding,
navigation servitude, environmental issues, historic properties, archeological concerns, and the National Historic
Preservation Act. These issues will frequently be controlling factors in the overall project development process.
2-5. Project Components and General Feature
a. General layout. A navigation dam is similar to
most other dams in that its intended purpose is to
impound water. However, it is usually designed so that
the water surface upstream of the dam is of such elevation
that there will be sufficient depth for navigating a relatively long distance upstream from the dam without having to go through another lock or to dredge excessively.
However, there are a number of factors--basically related
to costs and impacts on existing developments and on the
environment--which place limits on the upper pool which
will be maintained by the dam. Except possibly in the
case of impoundment for water supply, hydroelectric
power, or flood control, the dam is designed to allow the
same amount of flow through the waterway as existed
prior to construction of the dam. The height, or lift, of a
dam is the difference in elevations of the upstream pool
formed by the dam and the minimum pool or natural
stream surface below the dam.
Passage of vessels
between the upper and lower water levels is accomplished
by a navigation lock.
b. Operational requirements. Because the primary
purposes of a navigation dam are to impound water and to
regulate stream flows so waterway traffic can lock
through under almost all pool conditions, it is extremely
important that the project structures be laid out to allow
safe, timely, and efficient transit of the lock. The configuration of the upstream and downstream reaches of the
stream and the currents and velocities of the stream
caused by spillway discharges are critical factors in the
proper layout of the project--particularly for layout of the
upstream and downstream approaches to the lock.
c. Basic project components for low- to mediumhead dams. Lock and dam projects can be single-purpose
and only consider navigation, or may be developed for
multipurpose uses. The basic components of a low- to
medium-head navigation project (a low- to medium-head
dam is generally considered to be one with a normal lift
or differential between upper and lower pool levels of
EM 1110-2-2607
31 Jul 95
50 ft or less) could include one or more locks and several
of the following dam features:
(1) Gated dam and spillway or sill with stilling basin
and training and grade separation walls. The gates will
typically be of the tainter type. However, in some
instances, wicket or hinged-crest gates will be used in
conjunction with or in lieu of tainter gates.
(2) Overflow embankment or weir.
(3) Navigation pass, which will normally serve as the
above-mentioned weir, may include hinged-crest or wicket
(4) Nonoverflow embankment or concrete or cellular
walls (lock and dam separation and/or dam abutment).
(5) Gate operating machinery such as hoists and
hydraulic systems.
(6) Maintenance and/or emergency bulkheads for the
(7) Service bridge--typically limited to the taintergated portion of the dam.
(8) Drainage and grouting galleries.
(9) Seepage cutoff walls or other seepage control
(10) Channel armoring usually consisting of derrick
stone and riprap and, in some cases, concrete paving.
they do not have navigation passes. (There will always
be a permanent differential in upstream and downstream
pools.) These high-head dams are not likely to contain
hinged-crest or wicket gate sections. The following are
important characteristics of high-head dams:
(1) Vertical-lift gates have typically been used in
lieu of tainter gates because the structural dimensions for
the lift gates and piers are less than required for tainter
gates. However, tainter gates with supplemental sluice
(vertical-lift) gates are likely to be used more extensively
in the future as the procedures for operating the tainter
gates are simple and require minimal attendant labor-unlike the vertical-lift gate.
(2) Power-generating facilities will normally be
incorporated because there is typically a sufficient
impoundment above the conservation pool to make power
generation economically feasible. Also, these facilities
may be subject to private development and operation-depending on the legal environment at the time of
(3) Frequently, fish ladders will be provided if the
species of fish in the dam’s locality are migratory in
nature, such as those in the northwestern United States.
e. Multipurpose project components. The navigation
project with multiple-purpose functions should
accommodate each purpose as much as is economically
justified and technically feasible with priority of purposes
taken into account. Common multipurpose components
(1) Navigation lock(s) and dam.
(11) Buildings which will normally be used to facilitate both lock and dam operation (visitors, recreation,
administration, maintenance, storage, etc.).
(2) Flood control capability.
(3) A powerhouse.
(12) Electrical power generation using “run-of-theriver” flow--unless additional impoundment to extend the
generating period is feasible. Currently, inclusion of
power generation is a development of (and is funded by)
entities other than the federal government. However, the
generating component has to conform to navigation
requirements and meet the stability and safety requirements of HQUSACE.
d. Project components for high-head dams. Highhead dams (with a greater than 50-ft differential between
upper and lower pools) will contain most of the features
mentioned above for low- to medium-head dams, except
(4) Fish passage facilities.
(5) Recreation facilities (boating and other water
sports, enhanced fisheries, picnic facilities, etc.).
(6) Water supply intakes for municipalities and/or
(7) Features to enhance water quality downstream of
the dam, e.g., low flow controls and multilevel outlets.
(8) Water conservation.
EM 1110-2-2607
31 Jul 95
2-6. Examples of Navigation Projects and
Components of Dams
Except for the John Day Dam mentioned below, all of the
following are features of low- to medium-head projects:
a. Plates 1 and 2 are provided to show a perspective
and a section of a typical lock and dam on the Red River
Waterway and the various structural features used in this
dam. Primary control of flow is regulated by tainter
gates. The crest gate spillway is not provided as a navigation pass but primarily to supplement the flow capacity
of the tainter gate spillway during high river stages. The
crest gates are lowered during high water to increase flow
capacity and are used to fine-tune discharge rates when
the river is in pool.
b. Plate 3 shows the proposed Olmsted Locks and
Dam. This dam’s primary feature is the wide navigation
pass which is to be used by river traffic during a high
percentage of the year. During low-water stages the
upper pool will be maintained by wicket gates, and navigation traffic will pass through the lock. Typical sections
through the navigable pass monoliths are shown in
Plate 4.
c. The Melvin Price Locks and Dam project is presented in plan in Plate 5. This example includes nine
identical, 110-ft-wide tainter gate bays with two of the
nine used to separate the main and auxiliary locks. The
overflow section on the Missouri side is not designed to
function as a navigation pass. Plate 6 presents closeup
views of the tainter gate bay features.
d. The Smithland Locks and Dam project is presented
in Plates 7-9. This project is similar to the Melvin Price
project mentioned in paragraph 2-6c above. It has 11
identical, 110-ft-wide tainter gates and a non-navigable
fixed weir.
e. Examples of usage of earth-fill sections as a
damming surface or element are shown in Plates 10
and 11.
f. Features of the John Day Dam, an example of a
high-head dam with multiple-purpose functions, are presented in Plates 12 and 13. These features include tainter
gate bays, a lock structure, a powerhouse section, and a
fish ladder.
2-7. Existing Conditions
Much of the following will not be applicable to major
rehabilitation projects; however, the opposite is true for
new projects. Once the need for a navigation dam is
identified, a careful assessment must be made of the
natural physical characteristics of a stream and its valley,
as well as the conceivable dam sites. Various existing
site conditions can have profound effects on cost, operational feasibility, and acceptability to numerous entities
and interests.
a. Site conditions and restrictions. In long-settled
and developed regions, existing maps, geological surveys,
and hydrometeorological records may provide sufficient
data for preliminary design purposes. In other regions,
extensive field surveys and research of hydrological and
climatological records will be required before the project
can be designed. This subject is discussed more extensively in EM 1110-2-2602.
b. Climate.
(1) Range of temperature. Temperature extremes of
either heat or cold will influence the general dam design
and the detailed design of operating components and
structural features. In cases of extreme cold, the possibility of ice formation must be considered. Structural
design should include allowance for ice thrust on the
structural features exposed to the pool surfaces and on
gates, as well as the impact and abrasion of running ice.
Floodway openings must be designed to pass large volumes of ice to minimize the danger of ice jams forming.
In extremely cold climates, heating systems may be
required for winter operation of gates.
(2) Humidity. The degree of humidity inherent to
location on a water course must be considered in design
of electrical services, machinery, and corrosion protection.
The occurrence of frequent or prolonged fog or a tropical
combination of heat and humidity may present major
problems in design and maintenance of electrical
machinery and a structure’s metal parts.
(3) Climatological records. In the United States,
climatological data such as precipitation, evaporation,
wind speed and direction, and temperature are archived in
various formats by the National Oceanic and Atmospheric
EM 1110-2-2607
31 Jul 95
Administration (NOAA), a unit of the U.S. Department of
c. Topography. The plan for a navigation dam structure should conform to the topographical features of the
project area. If the required information is not already
available, maps should be prepared to show the pertinent
data based on surveys conducted for this purpose. Data
required for planning and design of the project include but
are not limited to the following:
(1) Information in regard to populated areas (location,
elevation, and other items) which will indicate possible
effects from project construction.
(2) Locations of railroads, highways, power lines,
natural gas pipe lines, flood protection projects, levees,
sewer outlets, water-supply intakes, pumping stations, and
input from the owners of those features which may be
affected by the proposed project.
(3) Locations of fishing and hunting preserves and
input from the owners of those features which may be
affected by the proposed project.
(4) Locations and pertinent data on bridges, dams,
dikes, wharves, pleasure resorts, and all other features that
might be affected by the project.
(5) Channel soundings, high and low water marks,
gage and historical river gage data.
more detailed coverage of all aspects of hydrology and
hydraulics, as these items relate to navigation dams,
including existing data and record sources, is found in
ER 1110-2-1404, ER 1110-2-1458, EM 1110-2-1604,
ER 1110-2-1461, and EM 1110-2-1605. For guidelines
that cover special hydraulic features of a project, see
EP 25-1-1.
e. Geology. To properly evaluate the suitability of a
site for location of the navigation dam and lock structures,
it is necessary to assemble and evaluate all the available
geologic information and perform new core drilling, probings, and soundings. Composition and depth of overburden, quality and type of underlying rock, and quality
and type of exposed rock are extremely important factors.
Subsequent foundation studies, based on the assembled
geologic information, will help determine whether the
structure should be founded on rock, soil, or piling. Also,
the geology of the stream bed will influence sediment
transport and stream-bed stability requirements.
f. Existing land ownership and usage. The consideration of real estate is not limited to the amounts and locations of that needed for the project and the associated
costs but must also include the current land uses and the
environmental and social issues associated with these
uses. Some real estate usage is so sensitive that development of a project based on usage of such “sensitive” real
estate would never come to fruition in today’s political
and legal climates. Real estate requirements for the
project features are discussed in more detail in
paragraph 2-14.
d. Hydrologic and hydraulic.
(1) Hydrologic studies. A watershed hydrology study
is one of the first needs in developing a navigable waterway. The hydrologic conditions along the waterway
length will determine required lift needed for a dam to
establish reliable navigation. Hydrologic studies for a
river basin identify the discharge frequencies and duration
a dam structure (located at any particular point within the
basin) must be designed to accommodate. Minimum,
normal, and maximum discharges are all significant to the
dam design.
(2) Hydraulic studies. Hydraulic studies for navigation dam design generally cover two distinct phases. The
first phase establishes the stage-discharge relationship and
its effect on the entire area affected by the proposed project under both existing and postproject conditions. The
second phase of hydraulic studies involves the design of
dams and other structures (i.e., their type, shape, size, and
siting to ensure satisfactory hydraulic performance). A
g. Environmental setting. Information on existing
environmental conditions will be necessary to prepare the
compliance documents required by existing federal regulations. Early and continuing communication with agencies
charged with protection of the environment is essential.
A finding of no significant impact (FONSI) is a prerequisite to project development and construction. Careful
planning to maintain or enhance the environmental quality
and mitigation measures may preclude or set aside the
potential negative impacts that would render the project
infeasible or not allow its approval. Also, high quality
resource management plans plus improved design and
operation procedures will help maximize environmental
benefits and help attain environmental quality objectives.
2-8. Navigation and Pool Operational
a. General. In general, the lock features and location prevail in importance to other project features and
EM 1110-2-2607
31 Jul 95
purposes. However, the following considerations associated with the dam and approach channels will have considerable bearing on good navigational approach
b. Channel depth and width. Navigation will be
enhanced by providing channel depths and widths for
movement and maneuvering of vessels at the desired
speeds, eliminating hazardous currents, and providing
pools stable enough to allow development of suitable
terminal facilities by navigation interests. The efficiency
of navigation can be enhanced by including navigation
passes for low-head dams and mooring facilities at locations remote from the dam to ensure that unattended tows
are not drawn into the dam and do not drift into the path
of river traffic. The bases for channel depth, channel
width, and lock dimensions are established by study of a
number of factors, including types and probable future
tonnage of traffic, types and sizes of vessels in general
use on connecting waterways, and developments on other
waterways which may be indicative of the type and size
of vessels likely to use the channel.
c. Control of hazardous currents. The slack-water
pools created by dams will reduce current velocities from
those existing in the stream’s natural state and, in general,
will eliminate hazardous rapids. However, new hazards
may be created. Vessels entering or leaving the locks
will have limited steering control at required low speeds
and can be drawn out of control by currents set up by the
spillway section of the dam. Approach walls and other
protection, for a considerable distance above or below the
lock, may be required to hold tows in line. Some restriction on the use of spillway gates adjacent to the lock may
be necessary. Maximum velocities and channel depths
usually will be found along the outer bank of bends, and
even slight curvature will tend to fix the natural deepwater channel closer to the outer bank. A lock aligned
with the natural deepwater channel will usually provide
the best navigation characteristics; locations in sharp
bends and where the lock structure will deflect a substantial part of the flow should be avoided. Model studies
and advice of experienced masters and pilots should be
considered in preparing a lock and dam layout to avoid
hazardous current conditions.
Regulation of upper pool.
(1) General. In addition to the flooding impacts of
the selected pool, consideration should be given to the
pool’s operational stability. A navigation dam should
ordinarily provide a fixed pool elevation with little stage
Dependable minimum upper pool stages
promote navigational reliability, growth in waterway traffic, and simplified development of port facilities. To
maintain the upper pool elevation at as near a constant
level as possible, gated spillway bays are usually provided
in navigation dams so that, by controlled gate operation,
both normal and flood flows can be passed downstream
through the bays.
(2) Configuration of dam. The regulation of all
flows from the impounded pool in the most efficient and
nondetrimental manner requires that careful consideration
be given to the functional shape, elevations, lengths, and
widths of the dam structures.
(3) EM 1110-2-1605 provides information on spillway capacity, spillway shape, spillway gates, stilling
basins, pier nose shape, abutments, overflows, and selection of the optimum upper pool elevation.
e. Hinged pool operation.
(1) A principal purpose of the hinged pool operation
is to eliminate or minimize impacts which would otherwise result from increasing stages and/or stage frequencies
upstream of the dam over those which existed before dam
construction. This operation takes into account the flow
of water and does not rely on a flat pool operation.
Hinged pool operation involves lowering the pool of the
dam several feet, usually 2 to 5 ft below normal upper
pool level during higher flows where adequate navigation
depths are available at the upper end of the pool. When
discharge falls the pool is raised to extend the backwater
effect above the critical reach to maintain navigation
f. Open river navigation.
(1) General. Where hydraulic conditions allow, it
may be desirable to provide a navigable pass across a low
damming structure to avoid the tow going through the
locking process each time it passes through the navigation
facility. Avoiding lockage can provide a substantial time
savings for both upbound and downbound tows. Stages
high enough to permit open-river navigation for a
significant portion of the year, individual high-water periods usually of considerable duration, and a gate regulating
system commensurate with the rate of river rise and fall
are necessary. A navigation pass weir or other section of
the dam, with or without crest gates, is necessary to
accommodate open river navigation.
(2) Dimensional criteria for a navigable pass. The
design must provide sufficient width for safe passage of
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tow traffic, including poorly aligned tows. In addition,
the pass must have sufficient depth for tows of the authorized draft, including a buffer for overdraft, tow squat,
etc. A model study should be considered in the design of
a navigable pass. At the present time (1993), the Corps is
operating dams with navigable passes on the Ohio, Ouachita, and Black Rivers. Pass widths vary from 200 ft on
the Ouachita and Black Rivers to 932 and l,248 ft on the
Ohio River. Two new navigable pass dams, Olmsted on
the Ohio River and Montgomery Point on the Arkansas
River, are in the planning stages. In addition, the Corps
operates dams on the Illinois Waterway, at which tows
transit the regulating wicket section during higher stages.
Gate types for navigable passes are discussed in Chapter 5. Further material relative to open river navigation
can be found in EM 1110-2-1605.
g. Swellhead. The impacts of swellhead (differential
head resulting from the flow restriction in the waterway
created by the lock and dam) during open river conditions
must be considered in the following instances:
(1) When tows are to navigate across a navigation
pass, the swellhead in the pass must be small enough to
permit the tows to pass through under adequate power to
move upstream and otherwise control their alignment.
Hydraulic studies must determine the optimum elevation
at which the top of the lock wall is to be inundated and
the area for flow through (over) the dam components, all
to provide flow capacity adequate to minimize swellhead.
(2) Swellhead at most low-head dams, regardless of
whether open river navigation is to be provided, can influence the real estate requirements. Swellhead greater than
1 ft may be allowed if open river navigation is not provided and if the costs of associated additional real estate
requirements are less than the costs of associated additional flow capacity required to reduce the swellhead.
2-9. Hydraulic Design Considerations
a. General. Much of the basis for hydraulic design
has been discussed above under the topics “Existing
Conditions” (paragraph 2-7) and “Navigation and Pool
Operational Requirements” (paragraph 2-8). Also, the
topic “Model Studies” (paragraph 2-10), discussed below,
is extremely relevant to hydraulic design. The following
items are intended to either reinforce or supplement the
content of these referenced topics.
b. Discharge and stages. Hydrologic studies for a
river basin identify the discharge which a dam structure
must be designed to control in order to satisfy the
navigational objectives of the project. The hydraulic
studies for navigation dam design cover two phases:
establishing the stage-discharge relationship over the
entire area affected by the proposed project under both
existing and postproject conditions; and designing the
dams and other structures, i.e., their type, shape, size, and
siting to ensure satisfactory hydraulic performance,
including navigation approach conditions and maintenance
requirements (i.e., dredging).
(1) Seasonal variations. Project areas subject to
periods of low runoff alternating with long periods of
high runoff are ideal sites for constructing a navigation
dam. However, detailed hydrologic and hydraulic studies
must be conducted in all cases to confirm this.
(2) Low flows. A properly functioning navigation
project must have sufficient water during low-flow
periods to satisfy evaporation losses, seepage from the
pool, seepage under the dam, and leakage past the spillway gates, in addition to providing adequate water for
lockages. Some projects may also have requirements for
water supply, irrigation, hydropower, and environmental
(3) Flood heights. In recent years, the Corps has
emphasized providing enough spillway capacity in navigation dams to pass the PMF. However, low-head and
medium-head dams of up to 50 ft will usually have an
overflow weir, and flood flows may go overbank unless
levees are provided. High-head dams of over 50 ft should
be provided with enough spillway capacity to pass the
c. Spillway design.
(1) Low- to medium-head dams. Typically, low- to
medium-head navigation dams will be designed to pass
flood flows utilizing not only the main spillway section
normally located within the river channel but also supplemental spillways located across the overbank. However,
on some low-head projects, extreme floods will overtop
the lock walls, and navigation will be directed to cease
(2) High-head dams. Spillways for high-head navigation dams are generally designed to pass the PMF
flows. They should also be designed in accordance with
other requirements contained in EM 1110-2-1603.
d. Ice conditions. It is necessary to determine the
volume and duration of ice conditions at navigation dams
so that ice control methods can be developed. Historical
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records coupled with site monitoring will be helpful. On
a stream where heavy ice formations are present, the
spillway bays should be made as wide as practical to aid
in passing the ice downstream so that it does not wedge
and build up against the structures.
e. References. More detailed descriptions of all the
above items, with information on where existing data are
available, are contained in EM 1110-2-1605. EM 1110-81(FR) and EM 1110-2-1612 provide information and
methods of estimating ice situations, growth, and duration
using winter air temperatures.
2-10. Model Studies
a. General. Physical model studies of the hydraulic
and navigational characteristics of the layout of the dam,
the dam spillway, training walls, channels, dikes, slope
protection, streambed protection, locks, and lock
approaches are an extremely important part of the planning and design for a navigation dam project. The physical model can be either fixed bed or movable bed and
should include specific site conditions. Mathematical
models, which are likely to be more economical than
physical models, are being used to a greater extent as
more accurate techniques are developed. The U.S. Army
Engineer Waterways Experiment Station (WES) usually
conducts these model studies. During preliminary planning
stages when alternative layouts and locations are being
considered, WES may be able to furnish information
based on its experience on other navigation dam projects.
b. Spillway. The navigation dam spillways provide
the necessary waterway openings for passing high and
low flows to maintain the upper pool level in a range
suitable for navigation. In addition to the guidance contained in EM 1110-2-1603, further information for design
of the number of spillway bays is required. The width of
the bay; the elevation, length, and shape of the spillway
crest; pier extensions (separation walls); stilling basin
baffles; and end sill can be found in EM 1110-2-1605.
This EM contains tabulations of model tests relating to
the above-listed items along with comparisons of calculated results versus model study results.
c. Forces on structural components.
In some
instances, it may be necessary to determine the downpull
loading, the buoyancy effect, or possibility of vibration of
a structural steel bulkhead or vertical lift gate when the
item is being lowered or raised in free-flowing water. A
scale model of the structure can be model-tested by WES,
and information on loadings, uplift, and vibration tendencies can be obtained.
d. Cofferdams. A movable bed model can be used
to examine the different stages of cofferdam construction
for a navigation dam project where the cofferdam (e.g.,
sheet pile cellular type) is located in the existing waterway. The last-stage cofferdam situation can be the most
important stage to examine in the model, because this
stage will cause an increase in the velocity of the water
going through the narrowed river opening. This increased
velocity can cause excessive movement of the river bed
material all across this location and undermine the river
arm of the cofferdam. The modeling results will indicate
specifically where the problem locations are. Thus, the
cofferdam may be configured with deflectors to shunt the
scour away from the cofferdam proper, and the stream
bed of the narrowed space where the final dam structure
is to be installed can be protected against scour with stone
or a weighted lumber mattress.
e. Sediment, debris, and ice handling.
(1) Sediment. A physical movable bed model can
be used successfully to determine shoaling and danger
points when a stream transports a heavy bed load of sediment. The model cannot predict amounts accurately but
can indicate locations where sedimentation is likely to
occur if suitable measures are not implemented. Rock
dikes, wing dikes, operating procedures, or other preventative measures can be designed into the project.
(2) Debris. The best method for passing debris,
especially keeping it away from the upstream lock
approach and chamber, can be determined through model
studies, and appropriate operating recommendations can
be adopted based on the results of these studies.
(3) Ice. Where ice buildup poses a threat to dam
structures, physical models of ice control methods can be
made at the Ice Engineering Laboratory at the Corps of
Engineers Cold Regions Research and Engineering
Laboratory (CRREL) in Hanover, NH. EM 1110-2-1612
provides additional information on ice control methods.
f. Stone protection. Physical movable bed models are
helpful in determining the locations where stone protection is necessary and in sizing the stone required to protect the river bed and banks from the scouring velocity of
the flowing water and wave wash.
2-11. Miscellaneous Engineering Considerations
a. General. This paragraph is not intended to cover
all “engineering” requirements but is intended to address
some of the engineering topics not otherwise covered in
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this chapter. However, inclusion of some items in this
paragraph is intended to reinforce information provided
elsewhere in this chapter.
b. Summary of principal functional requirements.
(1) The general requirement that dams should cause
the least possible delay to movement of traffic may be
satisfied by a small number of high nonnavigable dams or
a larger number of low dams with navigable passes where
practicable. The type of dam selected must be consistent
with the flow regimen of the stream and the height of
dam permitted by topography and available foundations.
(2) The dam should be sufficiently watertight to
maintain the desired pool level at the lowest probable
(3) Movable spillway gates should be capable of
sufficiently rapid and flexible operation to be opened for
passage of minor flash floods as well as major floods
without excessive fluctuation in pool levels or increase in
flood heights, and to be closed in time to hold the desired
pool level on a falling flow. Remote operation of gates
and individual operating machinery for each gate should
be considered.
(4) Floodway openings should be sized to provide for
passage of ice floes and drift likely to occur.
(5) The dam should be capable of passing sedimentary material which cannot be permitted to accumulate in
the pool.
(6) Design should not induce flooding on the waterway if at all avoidable. If unavoidable, some form of
remediation will be required.
c. Location of dam with respect to lock.
(1) General. Unless the navigation lock is in a channel separate from the dam or there is some anomaly in the
waterway to dictate a large separation, the dam will typically be located adjacent to the lock and in line with the
upstream lock gates. Also, the preferable access to the
lock and dam for operation and maintenance is from the
lock-side of the waterway, so the dam will typically be
located on the side of the lock opposite from the primary
operation and maintenance access.
Detailed layout
requirements, as related to navigation and hydraulics, are
provided in EM 1110-2-1611.
(a) Most waterways in the continental United States
that have the potential for navigational usage are already
developed. Thus, much of the future dam construction is
likely to involve rehabilitation or replacement, and it will
be done in a manner to facilitate use of portions of the
existing navigation features to the maximum extent practical, and will likely involve innovative techniques. The
required techniques may not be in total agreement with
the preferred layouts discussed in EM 1110-2-1611. For
example, the Upper Mississippi River-Illinois Waterway
System Navigation Study by the Corps of Engineers
North Central Division considers an increase in navigation
capacity by building an additional lock chamber through
an existing dam with the resulting layout being much
different than if the two chambers had been included in
the original construction.
(b) From the viewpoint of navigation, siting of the
lock is probably more important than siting of the dam
because it is desirable to locate the lock within that portion of the channel which will provide the best possible
conditions for navigation to approach the lock. Thus, the
dam location will usually be controlled by the lock location. Unless flow from the dam is diverted from the
downstream lock approach by a physical barrier or there
is a large separation between the lock and dam structures,
the dam cannot be located near the downstream lock gate
bay due to the adverse effects of the dam discharge on
navigation. Also, if the dam is located adjacent to the
downstream lock gate bay, provisions for chamber discharge are limited to within the downstream entrance to
the chamber and/or to the side of the lock opposite from
the dam.
(c) Where conditions warrant, highway or railroad
bridges may be located over the lock structure. In such
cases, the lock walls and/or the dam piers may serve as
bridge pier supports. The elevation of low-steel on a
fixed-span bridge can be minimized if the bridge is
located just below the downstream gates of medium- to
high-lift locks. The vertical clearance for navigation at
that location will be determined by the tailwater elevation
rather than the upper pool elevation. If the dam piers are
to be used to support a fixed-span bridge, the best overall
location of the dam is likely to be just below the downstream lock gate. Barkley Lock and Dam near Grand
Rivers, KY, on the Cumberland River is an example in
which the dam is located at the downstream lock gate and
the dam piers provide support for a railroad bridge.
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31 Jul 95
(d) From the perspective of structural stability and
design, it is usually advantageous to have the majority of
the lock chamber in the lower pool. This is particularly
true for the condition with the lock unwatered when the
lock wall stability is controlled by uplift and by water
pressures tending to push the lock walls toward the chamber centerline. Additionally, this placement of the lock
chamber reduces the length of the lock wall that acts as a
damming surface.
(2) Factors to be considered in regard to lock and
dam separation. In addition to those factors discussed
elsewhere herein, the following should be considered:
(a) Typically, there will be minimum separation
between the lock and dam in order to minimize construction costs and to promote efficiencies through keeping the
operations and maintenance activities for the lock and the
dam in close proximity.
(b) In those waterways in which the suspended sediment load is expected to be large, small separations are
advantageous for transport of sediment, because limiting
the size of the channel cross section will make velocity of
flow greater than in a larger channel with the net result of
less chance of sediment deposition.
(c) Locating the dam close to the lock may induce
scouring of the lock’s foundation. If the lock and dam
cannot be separated sufficiently to avoid this, solutions
such as paving the channel adjacent to the lock with
concrete or heavy derrick stone or other special solutions
may be required.
drainage, and compaction properties of the fill and foundation materials, and probable settlement of the foundation when loaded. Drilled caissons and excavation-type
caissons are two alternatives for unusual foundation material situations. Foundation settlement will be of major
importance where two dissimilar structures such as earthdike and masonry sections abut. Seepage from upper to
lower pool must also be considered.
(3) Rock foundation requirements and other geotechnical considerations. A sound rock foundation at a reasonable depth is frequently desirable and/or available for a
concrete navigation dam. Extensive geotechnical exploration and examination must be made of rock materials to
determine suitable founding levels, shear strengths, and
allowable bearing pressures. Foundation investigations
should also include possible grouting requirements for
seamy or cavernous rock, and the possible effect of saturation or passage of water through granular deposits,
seams, and other susceptible material. Final verification
of founding elevations for rock foundations is usually
done as part of the construction contract.
(4) Geotechnical exploration of the waterway. Sufficient information must be gathered along the length of
navigable waterway to determine dredging or channel
realignment requirements.
The characteristics of the
material (rock or soil) must be identified, as this may
have a significant impact on project cost.
e. Structure types.
(1) General. The design will be based on the geotechnical conditions at the selected site. Except for the
probable necessity of rock excavation, rock foundations
for dams may be the most desirable. Where rock suitable
for founding structures does not exist, soil or pile foundations may be required.
(1) Low- to medium-head dams. The majority of
the dam structure itself will likely be composed of reinforced concrete and may be founded on earth, rock, or
piling--depending on the geology of the selected site.
Portions not exposed to turbulent flow may be composed
of roller-compacted concrete, soil cement, and earth and
rockfill embankments. In many cases, overflow sections
may be composed of cellular structures (sheet piling filled
with granular materials, grouted riprap, etc.). The life of
these cellular structures will likely be controlled by the
longevity of the sheet piling, which can exceed 50 years
under favorable conditions. The gates will typically be of
structural steel. However, some experimentation is being
conducted to use fiberglass, plastics, and similar materials
for the wicket gates. The service bridge will normally be
of precast, prestressed girders topped with cast-in-place
(2) Properties of soil and rock. In the case of earthfill dam sections and concrete dams on earth or pile foundations, consideration must be given to the stability,
(2) High-head dams.
Stability requirements for
high-head dams will usually exclude or minimize use of
such features as earth and rockfill embankments, soil
(d) As stated above, flow through the dam will influence navigation approach conditions unless there is a
large separation between the lock and dam or a physical
barrier to divert the flow from the approach. Model
studies will best predict the effects on navigation where
the dam is adjacent to the lock.
d. Geotechnical design.
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cement construction, and cellular structures as used on
low- to medium-head dams. Typically, unreinforced
gravity concrete will be used, and it is likely the dam will
be founded on rock due to the typical geological and
topographical conditions which lead to use of high-head
f. Materials availability.
The types, suitability,
sources, and costs of principal construction materials
should be identified in early planning stages. Of particular importance is the identification of materials that are
not readily available or available from a number of
domestic sources.
g. Structural criteria. Early in the design process, it
is essential to develop reliable project feature dimensions
and identify the operational requirements (e.g., pool elevations, ranges of pool stages, probable structure types, and
foundation requirements). As the project development
evolves, this information must be kept up-to-date so as to
use available design resources efficiently. Divisions and
HQUSACE should be involved early in the planning
process to obtain the best overall design with the fewest
revisions during the planning and design period.
h. Topographical considerations and mapping
requirements. Accurate survey information is necessary
for the development and layout of a navigation project.
Information at the dam site and within the limits of the
navigable reach of water will normally be required. This
may require aerial photography and onsite surveys.
i. Real estate requirements and considerations.
Numerous real estate considerations are associated with a
navigation facility as stated elsewhere in this chapter.
Project details should be developed with sufficient
accuracy so as not to have to expand the number of rightof-way procurements as the project design develops.
2-12. Cofferdams and Other Temporary
Construction Requirements
a. General. In addition to design and construction
activities associated with permanent features, the following are some of the temporary features which must be
considered in planning and design.
b. Diversion alternatives. Depending on the circumstances, the dam may be built within the confines of the
streambed within a cofferdam, or it may be built within a
new channel that cuts off a bendway within the existing
waterway. The first method involves diversion of flow
within a zone contiguous with the construction site. In
the latter method, the construction site is isolated from the
existing waterway until the project is completed and the
flow is diverted through the cutoff channel.
detailed information relating to diversion is covered in
paragraph 2-10 of this manual and in EM 1110-2-2602,
which considers related diversion requirements for navigation locks.
c. Cofferdams.
As mentioned above, hydraulic
model studies may be needed to configure the cofferdam
layout if construction is to be within the confines of the
existing waterway. The cofferdam arrangement, used for
construction of Melvin Price Locks and Dam and shown
in Plate 14, is an example of cofferdam usage in staged
construction. However, if the dam is to be constructed
within a cutoff, the cofferdam is likely to consist of an
earthfill embankment. An important consideration is the
effective height of the cofferdam. The effective height
relates to the risks that are to be taken with regard to the
waterway stage at which the cofferdam will overtop and
the costs of overtopping; i.e., it must be determined when
the cost resulting from overtopping would be less than the
cost of raising the height of the cofferdam to minimize
the risk of overtopping. A more in-depth discussion of
cofferdams for locks is provided in EM 1110-2-2602.
Other specific guidance may be found in ER 1110-2-8152,
EM 1110-2-1605, and EM 1110-2-2503.
d. Alternate methods of construction. The use of
alternate methods to construct a navigation dam (other
than within conventional cofferdams) may have significant
advantages over conventional types of construction, in
both initial construction costs and required construction
(1) Alternative ways to construct a dam can include
construction “in-the-wet” or a reusable type of cofferdam
or a combination of methods. Construction in-the-wet
usually involves underwater excavation and foundation
preparation (including piles). The structure is then floated
into place and sunk or hoisted onto the foundation,
usually in segments to maintain a manageable size. The
segments may be filled with tremie concrete, or steel
shells may be used which are later filled with tremie
concrete. Consideration must be given to the requirements for constructing the segments in a yard and transporting them to the site, or providing a dry dock type of
facility (usually near the site). Large precast piers have
also been set in place with specialized equipment (Dutch
tidal barrier).
(2) The dam or portions of it may also be constructed within dewatered boxes, which can be reused, or
EM 1110-2-2607
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a more sophisticated mobile cofferdam may be used
which consists of a double-walled steel box that can be
floated, advanced, sunk, and dewatered with a selfcontained system and can also incorporate mechanized
concrete forming and delivery systems.
(3) Currently (1993), advanced studies are being
completed considering two alternative methods of constructing the Olmsted Dam to be built on the Ohio River,
in addition to a conventional cellular cofferdam type of
construction. One method would involve preparing the
foundation and drive piles in-the-wet and using a mobile
cofferdam to construct the dam sill and install gates and
machinery in conjunction with setting precast concrete
stilling basin shell elements filled with tremie concrete.
The mobile cofferdam would be floated, moved into position, sunk, layered with tremie concrete, and dewatered
when the tremie attained sufficient strength. Construction
of that segment of the sill would be completed in-the-dry.
The mobile cofferdam would then be flooded and floated
and the cycle repeated. The second alternate method
would be similar except large precast sill elements containing gates and machinery would be set in place on
bearing beams (and later grouted) with a large specialbuilt crane. Additionally, the fixed-weir segment of the
dam would be constructed in-the-wet utilizing cellular
sheet pile structures as has been common for several
(4) New technology or technology borrowed from
other fields should be considered when determining the
best way to build a dam in a riverine environment. Alternative methods may also be advantageous environmentally
and hydraulically, and may minimize navigational difficulties during construction. The method used to construct a
dam, the materials used, and the design chosen are closely
related and must be considered together.
e. Rights-of-way. Rights-of-way remote from the
project may be required for access to borrow sources,
staging, and other purposes. This may or may not be a
government responsibility. However, careful planning
should be done to ensure that there are adequate rights-ofway at the project site so that the contractor can use standard construction procedures if at all practicable.
2-13. Environmental and Aesthetic
Environmental requirements were briefly addressed in
paragraph 2-7. Unless the dam is remote from the lock,
aesthetic considerations should be consistent for both the
lock and the dam. Guidance relative to these subjects is
essentially the same as for a navigation lock and is available in EM 1110-2-2602.
2-14. Real Estate Considerations
Numerous real estate considerations are associated with a
navigation facility, and those concerning the dam site
itself may form only a small part of the picture. In the
investigation phases, the government may need temporary
access to private property to perform surveys and foundation exploration; assess possible requirements for highway, railroad, and utility relocations; determine
access-road alternatives; and for other reasons. In the site
selection stage, temporary access will be needed at a
number of locations to obtain adequate data for determining the best site for the structure. Project construction
and/or operation purposes will require real estate for staging construction activities and for project-induced flooding
of lands adjacent to the upstream channel, channel work,
navigation structure, access roads, and support facilities.
Surveys should be performed to identify the need to mitigate damages from levee underseepage due to changed
pool conditions. Mitigation may involve compensating a
landowner for estimated damages for changed industrial
and agricultural land use over the project life. An alternative to mitigation may be the need for levees, pumping
stations, and drainage structures to handle increased water
levels and induced underseepage from changed pool conditions. Other considerations which may pose major
concerns include the following:
a. Determining the types of rights-of-way required
(including easements and fee title properties).
b. Establishing the entity responsible for obtaining
real estate and performing relocations.
c. Estimating the lead times required to obtain
rights-of-way and perform relocations.
d. Identifying lands for mitigation of changed environmental conditions.
2-15. Site Selection
Site selection is one of the most important considerations
and is closely related to the other technical and procedural
considerations presented above. Selection of the dam site
is closely tied to selection of the site for the companion
lock, and the items that are important for one are important for the other. Briefly, the selection process should
consider the following:
EM 1110-2-2607
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a. A site which accommodates good approach conditions to the lock.
g. Whether
b. The characteristics and history of the existing
stream including, but not limited to, hydraulic and hydrologic considerations.
h. Whether other desired multiple purpose waterway
usage is accommodated.
c. The stability of the stream bed, i.e., whether the
stream carries a large sediment bed load and whether the
stream bed is stable or meanders.
d. Existing topographic and geologic conditions.
e. Existing uses of the waterway which may be
impacted by the raised pool level, such as levees, municipal water intakes, etc.
f. The effects of the waterway on the natural environment, i.e., wildlife, vegetation, fisheries, etc.
i. Whether construction at a site would produce
fewer adverse impacts (environmental, flooding, etc.) than
at another.
j. A site that is conducive to economical construction
and operation while satisfying the above objectives.
k. A site that will provide net project benefits and is
consistent with the national economic development (NED)
plan, as appropriate.
EM 1110-2-2607
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Chapter 3
Access and Support Facilities
3-1. General
Requirements for access and support facilities for navigation dams are briefly described below and are closely
allied to those for locks presented in EM 1110-2-2602.
EM 1110-2-2602 and EM 385-1-1 should be used as
principal resources in planning the access and support
facilities for navigation dams.
3-2. Access to Dam Site
The principal vehicular access to the lock and dam will
usually be on the lock side of the waterway because most
of the operation and maintenance activities will take place
there. Paved access to the end of the dam on the opposite
side of the waterway is also desirable, particularly when it
is necessary to deliver and receive heavy parts and equipment by truck at that location. Some means of vehicular
access at that location is needed for routine maintenance.
3-3. Pedestrian Access
It is desirable to have access across the full length of the
dam. Such access, however, may not be feasible if an
overflow section without piers is included in the dam. In
this situation, there is usually a more economical and
acceptable means to access other portions of the dam or
the lock from the shore than by a bridge, which would
require inclusion of piers solely for its support. However,
a service bridge between piers of a tainter-gated dam is
essential for routine operation and maintenance activities,
accessing tainter gate and bulkhead hoisting equipment for
repair, and manual control of the gate operating equipment. These bridges also provide support for the electrical and other utilities required to run the hoisting
equipment and may serve as a roadway for the bulkhead
3-4. Elevators, Stairways, and Ladders
a. Elevators. In spite of the fact that the vertical
distances between the lock wall and the service bridge on
the dam and between various levels on the dam piers are
typically quite large, elevators have not been used extensively. However, elevators may be used when justified
because they will provide access for the handicapped, a
means to lift and lower light freight, and routine access.
Further, access for the handicapped is a sensitive issue,
and compliance with legal requirements for accessing
certain areas may necessitate use of elevators. Current
access requirements involving the handicapped are referenced in an HQUSACE memorandum, “Uniform Federal
Accessibility Standards (UFAS),” dated 3 November 1986. A redetermination of “current” access requirements should always be made in planning for new
navigation dam construction. For example, the Melvin
Price Locks and Dam uses elevators to provide vertical
lift from the lock walls (also the nongated section of the
dam) to the level of the service bridge on the dam and
from the service bridge to the control house located adjacent to the main lock. Similar provisions for elevators are
included on Smithland Lock and Dam and will be
included on the Olmsted Lock and Dam, both on the Ohio
b. Other vertical access. Stairways and/or ladders
must be provided for vertical access where elevators are
not to be used and where use of small ramps is not feasible. Stairways should be provided in lieu of ladders
wherever practical when they will provide more convenient and safer access for personnel (i.e., stairways will not
routinely be considered impractical simply because provision of ladder access is more economical).
3-5. Equipment Access
In some cases, the service bridge over the gated section of
the dam provides the roadway or rail support for the
bulkhead crane. Obviously, the bridge design would be
controlled by the bulkhead crane loadings if one is to be
provided but, if not, the bridge design will be based on
loadings from pedestrians, tools, and support of disassembled parts of the gate hoisting equipment. In many
cases, equipment will be transported to and from the dam
on work flats and lifted to the level of the service bridge
by a jib crane mounted on one of the dam piers. Equipment access is discussed in more depth in subsequent
portions of this manual.
3-6. Operations and Maintenance Buildings
Normally, these buildings will serve jointly for operation
and maintenance activities for both the lock and dam.
They may be provided either at the lock and dam site or
at a centralized remote location, depending on operational
requirements. Generally, the purpose of these buildings
will be to provide offices, shops, and storage to support
the routine onsite operations and maintenance activities.
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3-7. Control Houses and Operating Platforms
Although provisions are included for remote operation of
gates at most modern navigation dams and should be
included for future dams, local control of gates must also
be provided to facilitate operation when remote operation
is not practical or desired. More detailed coverage of
operational and design requirements for control houses
and operating platforms is provided in subsequent
3-8. Control Rooms for Remote Lock and Dam
Depending on the size and layout of the project and types
of structural features involved (e.g., multiple locks), it
may be appropriate to operate the lock and dam gates,
lock filling and emptying valves, etc., from a centralized
control room having a reasonably good view of all operating features. This control room could be located on top
of a dam pier which extends above the tainter gate hoisting machinery room (as at Melvin Price Locks and Dam).
However, in most cases remote operation will be from a
control room on the lock wall. Remote operation will
require the visual aid of television cameras.
3-9. Storage Facilities for Protection of
a. Items to be incorporated in the construction. In
circumstances where the government is to furnish items to
the construction contractor, the government may provide
temporary storage facilities when warranted. For example, used sheet piling to be incorporated in a subsequent
construction phase may require storage to ensure that the
pilings are maintained in suitable condition for reuse in a
future construction phase. Normally, construction activities should be scheduled so that necessary storage of
items to be reused in future construction phases is provided by the contractor through provisions in the ongoing
b. Storage of operations and maintenance equipment
and spare parts. The aforementioned buildings will
usually provide for storage of operations and maintenance
equipment, spare parts, etc., of relatively small size and
weight. However, large items such as bulkheads and
bulkhead handling equipment will be stored either on the
dam structure or at some convenient location off the
c. Bulkhead storage.
If a bulkhead crane is
provided, some or all of the bulkheads will be stored on
the dam structure. If the bulkheads are to be stored off
the structure, a means of accessing the dam with the
bulkheads must be determined, providing for such possibilities as loss of the upper and/or lower pools, sunken
barges in the approach to the dam, and other conditions
which might obstruct barge access for bulkhead
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Chapter 4
Nonnavigation Considerations
4-1. General
a. Disturbances. Dams should be located to minimize disturbances to existing public and private installations such as roads, bridges, water intakes and other
utilities, the environmental setting, and pipelines. The
dam design may incorporate public recreation facilities
and should also take into account the site’s potential for
hydropower, in case hydropower facilities need to be
installed with the project or are a possibility for future
b. Water-surface elevation. Changes in water-surface
elevations and flow regimen of a stream due to a navigation dam may cause property damage or interference with
some stream uses. However, the value of the stream for
certain other uses may be increased. A navigation
improvement project should provide the maximum net
benefit to all interests concerned. The most cost-effective
plan for the sole purpose of navigation may require modification to accommodate the critical needs of other interests. Benefits to other interests may justify a more
comprehensive improvement which costs more than a
single-purpose improvement. A number of important
nonnavigation requirements and their effect on design and
operation of a navigation improvement are discussed in
the following paragraphs.
4-2. Effect on Floods
Unless the project has multiple purposes, a navigation
dam usually will be constructed to the minimum height
required to provide the prescribed project depth over
obstructive sections of the river bed or may be supplemented by dredging to provide required navigable depth.
At small discharges the pool will be nearly flat at an
elevation equal to or somewhat above the natural lowwater stage at the head of the pool. With larger discharges, velocity and water-surface slopes will increase
and stages at the head of the pool will rise if the lower
end of the pool remains fixed at the height of the dam. If
the dam has a height considerably less than the stage of
maximum floods, it may be so deeply submerged at high
stages as to have no appreciable effect upon the larger
floods. If the height of the dam approaches or is greater
than the maximum flood stage, lands not previously subject to flooding may be damaged by large flood discharges. Damage from flooding may be minimized by
setting the pool at the dam so that the sloping water
surface profile will provide only the desired project depth
over the controlling obstructive section. This elevation
will be determined by the slope which would produce the
limiting velocity for navigation in the lower portion of the
4-3. Effect on Drainage
a. Discharges. Throughout the length of a navigation pool, the water surface will be held permanently
above the natural low-water stage. In some cases, stages
at the dam may be permanently above the highest natural
flood stages. At the head of the pool, stages will fluctuate between normal pool level and flood stages in substantially the same manner as normal open-river stages.
The sustained increase in stage above natural low water
may interfere with the discharge of sewers, culverts, and
tributary streams which formerly discharged freely at low
stages. Deposits of sludge or silt due to reduced velocities may block sewers and culverts and raise tributary
stream bottoms to the point where flood heights are
affected. In the case of sewers and drainage outlets from
drained areas or areas protected by levees, pumping may
be required to provide satisfactory drainage. In cases of
permanently submerged gates on local flood protection
projects, it may be difficult to inspect these locations
adequately during floods for debris that would block the
gate from closing when needed. The use of a flap gate at
the discharge end of the culvert and a trash rack at the
upstream end plus periodic inspection of the gate area
during low discharge periods can help alleviate this problem. Where pumping plants already exist, the pool stages
may require increased use of pumps and pumpage against
increased average head. The sustained increase in stage
may also interfere with underground flow of surplus water
from agricultural bottom lands into the stream. Additional
ditching and pumping may be required to maintain satisfactory agricultural drainage.
b. Legal considerations. As the effects of navigation
pools upon drainage do not involve direct invasion or
overflow of lands, they have been defined by court decisions as “consequential damages,” which are not compensable in condemnation proceedings. However, damages
of consequential nature have been reimbursed by special
acts of Congress in several instances. In view of the
precedents established by such legislation, probable damage to sewers and drainage should be evaluated as a cost
of the project, and should be held to a practicable minimum. Damage can be averted or minimized by selecting
dam locations upstream rather than downstream from
important drainage outlets and tributary streams.
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4-4. Water Quality
Aeration provided by turbulent flow through dams can aid
in maintaining the dissolved oxygen requirements for
environmental needs. Low flow requirements should also
be met.
4-5. Water Supply
Where water supplies are drawn from the stream, a navigation dam will be of value in providing adequate depth
at the intake.
4-6. Mosquito Control
In some latitudes, whenever a relatively stable pool is
created, a suitable environment is provided for mosquito
breeding, particularly if floating debris, dead brush, or
aquatic vegetation is allowed to accumulate in shallow
marginal areas. In localities where mosquito breeding
exists, consideration should be given in design of structures to the desirability of fluctuating pool levels in order
to keep pools free of drift and undesirable vegetation and
to strand mosquito eggs, larvae, and pupae associated with
marginal vegetation and flotage. In most cases, projects
can be designed for such operation without significant
disadvantage to the primary function of the project.
b. Research. The following research efforts were
initiated by the Corps of Engineers in order to gain more
knowledge about and better comply with the preceding
environmental legislation.
(1) Dredged Material Research Program (DMRP).
The DMRP was completed by WES in 1978. The
program’s objective was to determine the environmental
effects of dredged material disposal and to develop
methods for eliminating or minimizing any adverse
(2) Dredging Operations Technical Support (DOTS).
The DOTS program was established in 1978 at the conclusion of the DMRP to assist all Corps elements in the
implementation of DMRP results. The program maintains
WES’s capability of responding to requests for assistance
from the Corps elements on all environmental problems
associated with dredging, dredged material disposal, and
habitat creation.
(3) Environmental and Water Quality Operational
Studies (EWQOS). The principal objective of EWQOS,
initiated in 1977, is to provide new or improved technology for planning, design, construction, and operation of
Corps civil works projects to meet environmental quality
objectives in a manner compatible with authorized project
4-7. Environmental
The National Environmental Policy Act (NEPA) of 1969
(PL 91-190) established a broad national policy directing
federal agencies to maintain and preserve environmental
a. Environmental impact statement. Section 102(a) of
NEPA requires all federal agencies and officials to direct
their policies, plans, and programs to protect and enhance
environmental quality; view their actions in a manner that
will encourage productive and enjoyable harmony
between man and his environment; promote efforts that
will minimize or eliminate adverse effects to the environment and stimulate the health and well-being of man;
promote the understanding of ecological systems and
natural resources important to the nation; use a systematic
and interdisciplinary approach that integrates the ecological, social, cultural, and economic factors in planning and
decision-making; study, develop, and describe alternative
actions that will avoid or minimize adverse impacts; and
evaluate the short- and long-term impacts of proposed
c. Environmental problems. Problems that must be
considered during navigation dam project development are
excessive sedimentation; resuspension of contaminants;
increased water temperature; water table effects; excavated material; impacts on aquatic, wetland, and territorial
habitats; interruption of migratory routes; modification of
riparian habitats; disruption of breeding or nursery areas;
increased turbidity; impacts upon wetlands; changes associated with the formation of bendway cutoffs; and any
necessary mitigation of damages.
d. Reference. EM 1110-2-1611 contains in-depth
coverage of environmental considerations for navigation
dam projects.
e. Fish and wildlife.
(1) Conditions for propagation and survival of fish
and wildlife may be altered extensively by a navigation
dam. Permanently raised water levels invariably destroy
spawning areas, nesting grounds, and dens. Clearing of
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brush and timber further reduces wildlife habitat, and may
leave inadequate cover and feeding grounds for survival
of existing wildlife. However, in many cases, equally
suitable spawning, nesting, denning, and feeding areas
may be formed at higher elevations, and habitat for some
species actually may be improved or increased. Some
types of dams may be barriers to the movement of migratory fish, in which case it may be necessary to provide
fishladders or other facilities. In other cases, the dams
may serve as barriers to rough fish, to the general benefit
of more desirable species. In general, stabilized pool
levels will greatly reduce the danger of fish being
stranded by low water during the navigation season.
Elimination of fluctuations in the zone between normal
pool level and natural low-water level will also reduce the
hazard to wildlife of having nests and dens flooded out
during the breeding season. Large stabilized pools may
also provide waterfowl resting or feeding areas suitable
for management as public hunting grounds and refuges.
Under proper control, other significant benefits may be
realized from the natural resources preserved or provided
by the pools.
(2) In designing structures, consideration should be
given to the recommendation of conservation interests as
to the effects of various pool levels, dam locations, and
operating procedures on valuable wildlife resources. For
example, location of a dam above or below a tributary
stream may have a decided bearing on the wildlife values
of the tributary basin. In some cases it may be practicable to modify a project, as designed for its primary purpose, in order to minimize possible losses to fish and
wildlife or to facilitate a method of operation which will
better serve fish and wildlife interests. For example, in
climates where ice will prevent navigation for several
months per year, the best method of operation for navigation alone might be to drain the pool in order to reduce
the volume of ice to be passed during the spring breakup.
However, the benefits of retaining a high pool level to
prevent crowding of fish under ice cover, preserve access
to dens and shelters of aquatic fur-bearers, and protect
aquatic vegetation used by fish and wildlife for food and
cover might justify design of the project on the basis of
holding full pool or near-full pool and providing for passage of the larger volume of ice. Operational drawdowns
at high discharges during the navigation season are also
objectionable to fish and wildlife interests, but are less apt
to be harmful to fish and wildlife than winter drawdowns.
4-8. Recreation
Although the effect of a project on existing recreational
facilities and natural recreational areas is usually an
important consideration, there may be times when the cost
of purchasing or replacing such facilities must also be
considered. Attention should also be given in the planning stage to project visitation and to the possibility of
converting access roads, buildings, and other facilities
used in project construction to recreational use upon completion of the project, in recognition of the fact that the
impoundment of a large body of water often improves the
area’s recreational potential or creates new opportunities
for recreational development. Particular attention should
be given to project features, such as beaches and boat
facilities, which can be developed most economically
before the pool is filled.
4-9. Hydropower
a. General. In the case of comparatively high-head
dams where the upper pool is above maximum tailwater,
the possibility of power development is evident. In the
case of low-head dams where a usable power head is
available for extended periods, the value of seasonal
power to meet coincident seasonal power demand may
warrant consideration of a power installation. In evaluating power possibilities, leakage through the lock and dam
and water required for operation of the lock must be
subtracted from the stream flow. The most suitable type
of power development at a navigation dam usually will be
a run-of-river plant, possibly with a limited drawdown for
daily or weekly pondage operation. Peak power operation
with large and rapid daily fluctuations in discharge can be
objectionable to navigation. To reduce the effect of
powerhouse operation on navigation activities, the power
facilities should be on the side of the stream opposite the
lock or locks when practicable. The power value of a
high dam, with seasonal storage to increase low flows,
may warrant consideration of a large power drawdown
with a supplemental lock and dam in the upper end of the
pool to maintain navigation during drawdown periods.
The best plans for development of power or navigation
alone may be in conflict, and a dual- or multiple-purpose
development will involve a compromise imposing some
degree of restriction on all uses of a stream. Plans for
operation must be sufficiently flexible to meet seasonal
variations in weather and stream flow and to permit
development of maximum overall benefits.
b. Minimum provisions for hydropower. Current
regulatory requirements which control whether hydropower is included in a project are outlined in ER 1105-2100. Hydropower should be included when it contributes
to the NED plan. In determining the NED plan, studies
should consider the economic benefits resulting from
project operation.
In the past, some projects have
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included minimum provisions to more readily permit
installation of hydropower in the future should it become
economically justified.
4-10. Zebra Mussels
a. Description. The zebra mussel (Dreissena polymorpha), a native of the Black and Caspian Seas of Central
Asia, matures to a length of only 2 in. However, it reproduces in great numbers; in fact, one female can release
30,000 to 100,000 eggs per year. Zebra mussel larva
(veligers) are free-swimming for about 2 weeks before
settling on hard surfaces where they mature. Once settled, they become firmly attached and are difficult to
remove. This ability to firmly attach to surfaces in large
numbers makes this mussel a major liability to users of
the waterways. In addition, the mussel has few natural
enemies, and it thrives in freshwater areas (especially in
flowing water) where there is a plentiful supply of food
and dissolved oxygen.
b. Introduction into North American waters. From
Asia, the zebra mussel spread to European freshwater
ports and then to most of Europe’s inland waterway system. Now (1993) the mussel has spread through most of
the major rivers and lakes in the north-central and northeastern United States. Although the exact mode of introduction is not known, it is suspected that a vessel
originating in an overseas freshwater port took on ballast
water which contained juvenile zebra mussels or larva.
Upon entering the freshwater ports of the Great Lakes, the
vessel discharged its ballast water, and the mussels then
had a new territory to colonize. It appears that this mussel will eventually spread to all the major inland
U.S. waterways.
c. Problems created.
(1) In the short time the zebra mussel has been in the
United States, it has fouled water intake structures for
water treatment plants, power plants, and industrial water
systems; crushed historic sunken vessels; made beaches
almost unusable; damaged boat hulls; and deprived fish of
a normal food supply. These mussels are also invading
navigation lock and dam structures in ever-increasing
numbers. Thus, as the mussel population increases and
spreads, the often serious and costly problems which its
presence causes will only worsen. The severity of the
problem is emphasized by the fact that several Great
Lakes power plants spend more than $250,000 annually
on zebra mussel control. For example, Detroit Edison
removes 140 tons of mussels a year from one power plant
on Lake Erie. In another example, a water treatment
plant serving a city of 50,000 people was forced to suspend service because its main intake line was clogged
with mussels. In the next 10 years, the cost of fighting
and controlling the mussel could reach several billion
(2) Zebra mussel attachment in sufficient numbers
and in a particular location could cause serious
operational problems for and malfunction of any one or
more of the following navigation-dam components: spillway gates, including side seal rubbing plates and sill
plate; spillway gate slots and spillway bulkhead slots;
stilling basin relief holes; and navigable pass or submergible gates and recesses. The problems include blockage
of relief holes and vents, blockage of water flows through
trash racks, and interference with spillway gate sealing
and seating. Spillway gates and other steel surfaces are
especially vulnerable because the mussels create an accelerating corrosive environment.
d. Control methods. The following procedures have
proven to be effective in removing the zebra mussel from
concrete and steel structures: hand or power scraping,
high-pressure water jetting, suction pump vacuuming,
thermal shock (elevating water temperature to over 90 oF),
drying with hot air, and use of biocides. Antifoulant
coatings, both toxic and nontoxic, have been used on
structures such as intake trash racks. The coatings will
need to be renewed in about 5 years. Steel structures
such as trash racks should be designed to be removable
for easy recoating and/or mussel removal.
e. Corps of Engineers actions. WES is engaged in
the Zebra Mussel Control Research Program, a multimillion dollar, Congressionally mandated project to investigate the environmentally sound control of zebra mussels
in and around public facilities. The program will monitor
the spread of the mussels, test certain antifouling coatings
in infested areas, and explore the use of new control
devices, methods, and designs. The gravity of the zebra
mussel problem, as it relates to the operation, maintenance, and longevity of Corps navigation lock and dam
structures, makes it a “must” that all future designs take
into account the necessity for mussel control and elimination. WES is the best source of information at the present
time (1993).
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Chapter 5
Types of Navigation Dam Structures
discussion describes these gate types and presents advantages and disadvantages of each.
a. Tainter gates (radial gates).
5-1. General
A navigation dam is composed of one or more types of
structures that operate together to dam a pool of water.
The components will be dictated by site flow conditions,
geotechnical considerations, operational and maintenance
requirements, construction considerations, and requirements of the user (the towing industry). Spillway types
normally provided for navigation dams include the following: gated--nonnavigable, gated--navigable, fixed crest-overflow, and fixed crest--nonoverflow.
5-2. Gated Nonnavigable Spillway
The type of gate selected also controls the dam sill and
associated piers. Gate types typically used for a nonnavigable spillway include tainter (radial) gates, hingedcrest gates (Bascule, Pelican, and flap), vertical-lift gates,
roller gates, and wicket gates. (Gate types which have
been used in the past but are not recommended for use,
except in special situations, are bear trap gates, drum
gates, and inflatable rubber gates.)
The following
(1) General. The radial gate most commonly used
on navigational projects is the tainter gate (see Figure 5-1
and Plates 2, 6, 8, and 13). In its simplest form, a tainter
gate is a segment of a cylinder mounted on radial arms
that rotate on trunnions anchored to the piers. Because of
its simple design, relatively light weight, and low hoistcapacity requirements, the tainter gate is considered one
of the most economical and most suitable gates for controlled spillways. The use of side seals eliminates the
need for gate slots that are conducive to local low-pressure areas and possible cavitation. Currently, the preferred practice is to carry the water load with a skin that
transfers the load to vertical structural sections. The load
is then transferred to deep horizontal beams (usually
three) which then transfer the load to the trunnion arms,
the trunnion yoke and hub, and the pier trunnion girder
and anchorage. Several navigational projects (for example, Cannelton and Markland) use a “stressed skin” tainter
gate, and although this gate may be somewhat lighter, it is
more difficult to design and construct. The tainter gate is
raised and lowered by wire rope (chains are also used at
Figure 5-1. Tainter gate
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older installations) attached at both ends to avoid
introducing torsional stress into the gate. Gates are
usually manipulated by individual hoists, one at each end
of the gate. Counterweights on smaller gates will reduce
required power but will add to the total weight of the
structure. Tainter gates built to heights of 75 ft and
lengths of 110 ft have been used for navigation dams.
(2) Gate and spillway geometry. In many cases, it
may be advantageous to use same-width spillway bays
and lock chamber so that the same emergency closure
may be utilized on both. It is desirable, but not mandatory, that the trunnions of tainter gates be placed above
high water, and essential that the gate itself be capable of
being raised above high water. Trunnion elevation is set
above most floods.
Typical trunnion submergence
allowed for trunnion girders is a maximum of 5 to 10 percent of the time. When in the closed position, the gates
should have at least 1 ft of freeboard above the normal
upstream pool. On large pools where fetch for wave
setup is large and water conservation is important, more
than 1 ft may be required. Gates should be designed to
clear the highest flood with allowance for floating debris.
Typical clearance is 1 to 5 ft above the PMF. Special
consideration may be appropriate for projects with major
flood levees along the overbanks. Often the maximum
stage will occur just before the levees are overtopped.
Subsequent discharge increases would result in lowered
stages because of dispersion of flows through the protected areas. For spillways in such locations, the maximum gate-opening height would be set at 1 ft above the
adjacent levee crown elevation. Another consideration is
raising the bottom of the gates to allow accidental passage
of barges through the gate bays without damage to the
tainter gates (although speed of operation usually
precludes such action). Skin plate radius ranges from 1.0
to 1.2 times the damming height of the gate. The radius
of the gate is affected by the vertical distance between the
bottom of the gate in the lowered position and the low
steel of the gate in the raised position. Spillway bridge
clearance may also be a factor in determining the gate
radius and the trunnion location. For design guidance,
refer to EM 1110-2-1603, EM 1110-2-1605, and
EM 1110-2-2702.
(3) Advantages. Tainter gate installations, as opposed
to other types, have the following advantages: lighter
lifting weight with smaller hoist requirements; adaptable
to fixed individual hoists and push-button operation
(individual hoists may have a lower first cost than gantry
cranes and require fewer operating personnel); less time
required for overall gate operation (more than one gate
can be operated at the same time); and favorable discharge characteristics.
(4) Disadvantages. Tainter gate installations, however, have the following disadvantages: radial arms
requiring more pier concrete and foundation concrete, i.e.
longer and higher structure; the encroachment of the
radial arm on the water passage; the necessity for long
radial arms where the flood level, to be cleared, is
extremely high; and relatively tall, narrow piers which
may not perform well during large magnitude seismic
events, especially if the motion is applied perpendicular to
normal river flow.
(5) Radial gates. Gates of a configuration similar to
that of tainter gates, but which are raised or lowered with
hydraulic cylinders instead of cables, are usually referred
to as radial gates. In Europe, these gates are now
normally used in lieu of cable-hoisted gates. Besides
sharing the advantages listed above, the radial gates may
be more economical.
(6) Reversed tainter gates. Reversed tainter gates
are sometimes used (especially in Europe). This configuration transfers the water load by putting the steel
trunnion arms in tension and the concrete pier in compression, which is advantageous. However, the overall length
of pier and stilling basin will usually be increased. Passing pack ice and debris is not accomplished as well as
with conventional tainter gates. The presence of ice,
debris, and trash in U.S. waterways would probably preclude the use of the reversed tainter gate.
(7) Submergible tainter gates. Submergible tainter
gates were developed to allow passage of ice without
having to use large gate openings. Two types have
evolved, one in which the top of the gate can be lowered
below the normal upper pool elevation and the piggyback
gate, in which a shaped lip on the top of the gate or a
double skin plate can be used to keep the flow off the
back of the gate. Hoist loads are much greater in deep
submerged positions and must be considered in machinery
costs. Vibration of submerged tainter gates has been so
prevalent that such gates should not be considered without
the concurrence of Corps of Engineers Civil Works, Engineering Division (CECW-ED).
(8) Tainter gate piers. Tainter gate piers are concrete with a precast/prestressed concrete or steel trunnion
girder anchored into the pier with post-tensioned anchors.
The pier thickness varies with height and loading conditions but is usually 10 to 15 ft. The gate sill is also
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concrete with embedded metal sill plates. The pier and
gate sill are separate gravity type structures on larger
projects; however, they may be combined into one unit
when maximum width-of-monolith requirements are met.
These combined units may be shaped as a T, U, L, or
some combination of these shapes. The overall size of
the structure must conform to requirements designed to
meet constructibility limitations and to control cracking.
Most massive concrete structures require a special study
(nonlinear, incremental structural analysis or NISA) which
must be accomplished in accordance with the requirements of ETL 1110-2-365 (see Chapters 9, 11, and 12
also). Other considerations, such as batch plant size,
navigation during construction, and cofferdamming concerns, may control the size of the monoliths.
b. Hinged-crest gates.
(1) General. Hinged-crest gates are known by a
variety of names including Bascule, Pelican, and flap
gates. These gates are hinged at the base to a dam sill
and are raised to retain pool and lowered to pass flows.
They can be straight or curved to fit the dam sill crest
when in the lowered position. The plate is reinforced
with vertical and horizontal members and is fitted with a
torque tube at the base or separate hinges. These gates
are normally sealed at the base and edges when in the
raised position (see Figure 5-2).
(2) Automated operation. Automated operation of
hinged-crest and Bascule gates may be considered. Such
automation was included on the hydraulically operated
Bascule gate on the Jonesville Dam, which began operation on the Ouachita-Black Rivers Navigation System
around 1970. A signal initiating from a floatwell causes
the hydraulic cylinders to lower the gate to compensate
for flow which would cause the upper pool stage to
exceed the desired level. The cylinders raise the gate
when the upper pool begins to fall below the desired
level. Some problems were encountered with the Jonesville Dam automated operation when there was a lot of
wave action on the river, since the signaling process was
extremely sensitive to constant cyclic variation in water
level. (Stillwater operation did not present a problem.)
Also, there was leaf vibration initially, and spoilers had to
be fabricated on the gate leaf to prevent excessive
(3) Torque tube construction. Where the gate is
constructed with a torque tube, the torque tube is
supported on bearings at intervals along the gate. The
gate can be raised or lowered by a crank arm powered by
a hydraulic cylinder. A hinged-crest gate can also be
supported by a number of separate hinges, with an operating stem (a screw stem or hydraulic cylinder) attached to
one or both ends of the gate at the top. As the stem is
pulled, the gate rises. The screw or cylinder is supported
Figure 5-2. Hinged-crest gate
EM 1110-2-2607
31 Jul 95
so that it can rotate to maintain alignment with the rotating gate. This same kind of gate can be operated by
means of hydraulic cylinders mounted beneath it which
push it to the up or closed position. One, two, or more
cylinders can be used depending on the gate length. The
hydraulic piping to the cylinders is interconnected so that
the cylinders will move in unison.
(4) Gate design. The design of the crest gate itself
and the means of actuation normally depend on the location of the gate, the application, the size of the gate, and
the head on the gate.
(a) The simplest form of hinged-crest gate is the flat
stiffened plate hinged at the bottom and operated by a
screw stem or hydraulic cylinder connected to the top of
the gate at one end. This type of hinged-crest gate is
limited to approximately 35 ft of length by 8 ft of height.
Gates that are longer or higher than this may require an
actuator at each end.
(b) The torque tube-style hinged-crest gate, which
uses the torque tube along the invert with the actuator
mounted in a compartment in the abutment, produces an
overflow between the abutments with no obstructions.
The operator may be enclosed in a chamber where it is
not exposed to the weather. Torque tube-style hingedcrest gates are normally limited to approximately 35 ft
long by 10 ft high because of the size of the torque tube
required for larger gates. However, 5-ft-high gates as
long as 200 ft have been constructed with operators provided at each end.
(c) The hinged-crest gate with hydraulic cylinders
underneath can be made in much longer lengths. The
gate can be made in a number of sections (joined in the
field) to total 200 ft or more. Hydraulic cylinders are
placed at intervals beneath the gate to raise and lower it.
The main advantage of this type of gate is the long
lengths of gate that are possible. The disadvantage is that
there must be a drop in elevation downstream of the ogee
crest to be able to mount the cylinders, or the cylinders
must be mounted in pits or holes downstream of the crest
(d) The standard Bascule gate design consists of a
torque tube with a leaf extension. The gate is rotated
approximately 70 deg from fully raised (closed) to fully
lowered (open) position. Bearings anchored at intervals
along the length of the spillway support the torque tube.
A lever arm extends from the torque tube and is positioned by a hydraulic cylinder operator. The standard
Bascule gate is practical up to heights of approximately
10 ft, depending on the length of the gate, operator
arrangement, and structural limitations.
(e) The Pelican gate usually proves to be more economical than the standard Bascule gate for many applications and is especially suitable for greater heights and
lengths. Gates over 13 ft high have been built, and
heights of over 20 ft are feasible. The Pelican gate
design consists of two curved plates with internal braces
and vertical bulkhead ribs forming a strong closed-shell
structure. The ribs extend through the bottom of the gate
and form supports for the gate hinge pins. The stationary
portion of the gate bearings consists of a series of bearing
supports anchored at intervals along the length of the
spillway. A small diameter pipe section may be welded
to the bottom portion of the gate to make contact with the
longitudinal rubber seal at all gate positions. Hydraulic
cylinder operators are located either on piers at the ends
of the gate or on the downstream side of the gate.
(5) Dam sills and piers. Hinged-crest gate dam sills
and piers are concrete. The sill and pier are normally
constructed as a single monolith. Operating machinery is
normally mounted on tall piers or housed in a watertight
chamber so that it is not submerged, but current
technology allows submerged hydraulic cylinders.
c. Vertical-lift gates.
(1) General. The vertical-lift gate, with wheels
(rollers) at each end, moves vertically in slots formed in
the piers and consists of a skin plate and horizontal
girders that transmit the water load into the piers (see
Figure 5-3). Reference is made to EM 1110-2-2701 and
EM 1110-2-1603 for design of vertical-lift gates. The
gate must be mounted on rollers to permit movement
under water load. The vertical-lift gate, like the tainter
gate, must be hoisted at both ends, and the entire weight
is suspended from the hoisting chains or cables (cables
are generally desirable). Piers must be extended to a
considerable height above high water in order to provide
guide slots for the gate in the fully raised position. Vertical-lift gates have been designed for spans in excess of
100 ft. High vertical-lift gates may consist of two or
more sections in order to facilitate storage or ease passing
of ice and debris. However, this does increase operating
difficulties, because the top leaf or leaves have to be
removed and placed in another gate slot. Historically,
gantry cranes traveling on the spillway deck have been
the standard method of operation for vertical-lift gates;
however, fixed hoists may be justified, especially if speed
is important or remote control is desired.
EM 1110-2-2607
31 Jul 95
Figure 5-3. Vertical-lift gate
(2) Flow regulation. Regulation of flow is accomplished by means of single-section gates with variable
discharge between the bottom of gate and the sill, and
multiple-section gates consisting of two or more sections
in the same slot with variable discharge between the sections or beneath the bottom section. The multiple-section
gate may or may not be equipped with a latching mechanism permitting operation as a single-section gate when
(3) Spillway discharge. The spillway discharge is
controlled by raising the gates or the individual sections,
as necessary, by increments. Dogging devices operated
from the piers at the deck level engage projections spaced
at intervals on the gate, permitting disengagement of the
crane after the gate is raised to the proper elevation to
give the required discharge.
(4) Gate types. Vertical-lift gates may be classified
according to the method used to transfer the water load to
the spillway piers, as follows:
(a) The fixed-wheel gate has wheels that revolve on
fixed axles, which are either cantilevered from the body
of the gate or supported at each end by the webs of a
vertical double girder attached to the gate framing. The
wheels may also be mounted by pairs in trucks which
carry the wheel loads through center pins to the end girders attached to the gate frame.
(b) The tractor gate is equipped at each end with one
or more endless trains of small rollers, which are mounted
either directly on the end girder or on members attached
to the end girder.
(c) The stoney gate has an end bearing consisting of
a train of small rollers between the downstream flange of
the end girder and the track on the pier. Since the rollers
revolve in contact with both girder and track, the roller
assembly moves in a vertical direction only half as fast as
the gate and must be supported independently.
(5) Most common gate. Of the types mentioned, the
fixed-wheel gate is the most common. It is adapted to
long spans since provision can easily be made for rotation
of the end bearings due to deflection of the gate body. It
can transfer heavy, moving loads to the piers without the
close track tolerances necessary for tractor or stoney
gates. With cantilevered wheels, a gate slot of minimum
depth can be used.
(6) Advantages. The advantages of a vertical-lift
gate installation are numerous: it reduces pier dimension
in upstream-downstream direction; its gate design is simple; it provides a clear gate opening with no encroachment, when raised, of any part of the gate structure on the
water passage; it is more adaptable to extreme pool fluctuations because it is lifted bodily out of the water; it
EM 1110-2-2607
31 Jul 95
eliminates design of complicated prestressing systems; and
it may allow for other than in-place maintenance.
(7) Disadvantages. The disadvantages encountered in
the use of vertical-lift gates include: a heavier lifting
load, which requires greater hoist capacity; storage or
pier-height requirements, which may necessitate use of a
sectional gate; a more labor-intensive operation; greater
time required for gate operation if only one crane is provided; and gate slots that can lead to cavitation and debris
(8) Dam sills and piers. Vertical-lift gate dam sills
and piers are concrete. The sill and piers may be constructed as separate monoliths or as a single monolith.
Pier thicknesses of 8 to 15 ft are normally used,
depending on gate width and height. Steel members
should be embedded to serve as a sill plate and as bearing
and armor members in the guide slots.
d. Roller gates. A roller gate is a long metal cylinder
with “ring gears” at each end that mesh with inclined
metal racks supported by the piers. The cylinder is
braced internally to act as a beam to transmit the water
load into the piers (see Figure 5-4). The effective damming height of the structural cylinder can be increased by
means of a projecting apron that rotates into contact with
the sill as the gate rolls down the inclined racks. The
gate is raised and lowered by means of a chain or cable
wrapped around one end of the cylinder and operated by a
hoist permanently mounted in the pier. The rolling movement of the gate and the limited amount of frictional
contact at the sealing points permit comparatively fast
operation with a small expenditure of power. Roller gates
have been built with a damming height of 30 ft, with
lengths up to 125 ft on pile foundations and 150 ft on
rock foundations. Roller gates are efficient in their power
requirements and can be used for wider spillway bays
than other types of gates. However, complexity of construction and the maintenance required by the hoisting and
roller system are disadvantages of this type of gate. Sills
and piers for roller gates are comparable to those of other
gates of similar height and width.
e. Wicket gates.
(1) Wicket-type gates have been utilized for navigation dams for over 100 years. These gates are now normally considered for navigable pass dam spillways, but
they will also function as nonnavigable spillways.
Although several types have been utilized in the past,
current new projects utilize a bottom-hinged wicket gate
with consideration given to chanoine-type wickets. The
gates can be lifted into position with a hydraulic cylinder
applying force to the downstream side or to a crank, or
they can be hoisted into position with a boat or gantryoperated crane or winch. Safety considerations and ease
of operation during variable river stages and climatic
conditions have generally led to the requirement for
hydraulic cylinder operators. These cylinders may be
located in a dry gallery or in a wet recess; however, silt
must be excluded from any recesses. The wickets are
generally held in an up position with a prop or strut
which slides in a hurter track (see Figure 5-5). This
allows the cylinder piston to be retracted except during
operating cycles. A gate with the cylinder rod attached
directly to the back to hold the gate in position, as well as
to raise and lower it, is also being tested.
(2) Wickets constructed in the past were generally of
steel or iron framing with timber leafs. Steel is the material most suitable for new construction, with composites,
stainless steel, or aluminum as possible alternates.
Wickets which are hinged at the base have the advantage
of simplicity and cannot be “flipped” up by thrust from an
upbound tow and then held partially up by river currents.
The chanoine-type wicket is hinged just below its center
point to a collapsible horse and held in place with a prop.
This type of wicket is raised with the leaf in a horizontal
position and then tilted into position by the force of water.
This method requires less hoisting force than other methods, but the assembly is more complex and the wicket can
be “kicked” up by a tow and held partially up under
extreme conditions.
(3) Wicket gates are planned for the Olmsted Locks
and Dam project on the Ohio River. These gates are
bottom-hinged and are raised hydraulically. They are
nominally 10 ft wide by approximately 26 ft long (see
Plate 4). Wider gates are feasible. Advantages of wicket
gates are low initial cost of construction, lighter weight
(which allows offsite maintenance), variability in controlling pool, adaptability in incorporating redundant or protective features such as multiple ways to raise the wicket
(hydraulically, with boat-operated backup), and breakaway props or dogging devices to limit damage in the
event of towboat impact. Wicket dams are less subject to
damage in high-seismic-force areas than a dam with piers,
and are also more aesthetically appealing.
(4) The main disadvantage of wicket gates is the
difficulty in providing for maintenance of the wicket
assemblies. Maintenance may be accomplished with an
unwatering box which is placed over the sill and
dewatered to allow removal and replacement of one or
more wickets at each setting. Proper floating plant,
EM 1110-2-2607
31 Jul 95
Figure 5-4. Roller gate
Figure 5-5. Wicket gate
EM 1110-2-2607
31 Jul 95
anchorage, and equipment must be provided. This is most
easily accomplished by providing quick change-out
designs and spare wickets and operating machinery.
(5) Wicket dam sills are concrete. Piers are not
required. The length of sill monoliths is controlled by
cracking and constructibility requirements.
f. Bear trap gates, drum gates, and inflatable rubber
gates. These gates have been utilized but are generally
not recommended for current consideration. A brief discussion is included for reference (see Figures 5-6, 5-7,
and 5-8).
(1) Bear trap gates consist of two leaves. When in
the lowered position, the upstream leaf overlaps the downstream leaf. The gate is raised by applying upper pool
pressure to a chamber under the leaves. This pressure,
sometimes supplemented with air or hydraulic cylinders,
raises the dam gate. These gates generally retain a pool
differential of 20 ft or less and are normally about 90 ft
wide. They are ingeniously conceived but can prove
difficult to maintain. Silt or sand deposits in or under the
gates are particularly likely and may make it impossible
to fully lower or raise the gates.
(2) Drum gates are generally operated on a principle
similar to the bear trap. The drum gate may be constructed as a segment of a circle and hinged on its downstream end. A watertight sill chamber is provided for the
gate. To raise the gate, upper pool pressures are introduced to the chamber. This force may be supplemented
by flotation chambers or hydraulic cylinders. The major
difficulty encountered with this gate is the necessity to
exclude silt and sand from and maintain seals on the
(3) Inflatable rubber dams are rubberized fabric tubes
which are anchored to a sill and inflated to form a dam.
These dams are limited to very low-head project usage,
are subject to puncturing and vandalism, and are not
recommended for major projects.
Gated Navigable Spillway
Navigable pass spillways permit the passage of tows over
dams without the locking requirements. At some locations, natural river discharges are sufficient during a portion of the navigation season (which could be continual
throughout the calendar year, or extend over part of the
calendar year only) to obtain the authorized navigation
depth. This is an advantage from the operational standpoint because locking delays are eliminated. However,
during periods of low discharges, the dam must be raised
to ensure sufficient depth for navigation. Movable gates
which can be traversed may be attached to a sill to form
such a dam.
a. Rationale. The primary need for a navigable pass
is a dam which provides an area free of piers or other
obstructions; therefore, the design of a navigable pass
must provide for sufficient clear width for safe passage of
tow traffic, including poorly aligned tows. At some locations this may include two-way traffic. In addition, the
pass must have sufficient depth for tows of the authorized
draft, including a buffer to account for overdraft, tow
squat, etc. Model studies have shown that a navigable
pass should have a minimum cross-sectional area 2-1/2
times the area blocked by a loaded tow. Current direction
should be aligned normal to the axis of the navigable
pass, and velocity through the pass must be low enough to
allow passage of upbound loaded tows of the horsepower
range that operates on the waterway. A model study
should be considered in the design of a navigable pass.
At the present time, the Corps is operating dams with
navigable passes at projects on the Ohio, Ouachita, and
Black Rivers. Pass widths vary from 200 ft on the
Ouachita and Black Rivers to 932 and 1,248 ft on the
Ohio River.
b. Gate types. In addition, the Corps operates dams
on the Illinois Waterway at which tows transit the regulating wicket section during higher stages. Gate types
usually considered for navigable passes include chanoine
wickets, hydraulically operated bottom-hinged gates, and
hinged-crest gates. Bottom-hinged wickets are currently
being designed for the Olmsted Locks and Dam project
on the Ohio River. These wickets are 26 ft long, 9 ft
8 in. wide, and have a 4-in. gap between gates. This
project will provide a 2,200-ft-long navigable gated spillway dam which will regulate river flows as required for
navigation (see Plates 3 and 4). Descriptions for wicket
gates are included under paragraph 5-2e. Hinged-crest
gates can provide the clear pass area required if designed
without piers. Hinged-crest gates are being designed for
the Montgomery Point project on the Arkansas River.
These gates are nominally 30 ft long and retain a maximum pool differential of about 13 ft. Discussions of
hinged-crest gates and drum gates are contained in paragraphs 5-2b and 5-2f.
c. Additional benefits. Navigable pass gate spillways
may provide additional benefits. Because they are generally less massive they are less costly to construct. They
are aesthetically pleasing because they are submerged a
portion of the time and are less imposing than a
EM 1110-2-2607
31 Jul 95
Figure 5-6. Bear trap gate
Figure 5-7. Drum gate
EM 1110-2-2607
31 Jul 95
Figure 5-8. Inflatable rubber gate
tainter-gated structure when raised. They may be less
likely to be struck by a tow because they are lowered
during higher river conditions, and a weak-link protection
is easily accommodated for excessive impact. These
spillways generally offer more redundancy because the
gates are smaller and there are more gates, and it is generally easier to provide them with a backup operating
system, such as a normal system which raises the gate
with hydraulic cylinders, as well as a boat-operated
backup system. They may perform better in areas of high
seismicity because of lower structural height and lower
mass. They are also more adaptable to multiple operating
settings which spread flow over the width of the river or
concentrate it. The most important negative consideration
is that maintenance of these spillways may be more difficult to accomplish and requires careful planning.
5-4. Fixed Crest
foundation (see EM 1110-2-1605). Additionally, the
uncontrolled spillway may raise the flood level of certain
frequency floods and may, therefore, require mitigation of
this effect. Fixed-crest dams may be navigated, in some
instances, during high water events which provide sufficient clearance over the weir. A lock and dam project
with only an uncontrolled spillway will usually require
higher lock walls than a project with a controlled spillway. An operational disadvantage of navigation projects
with uncontrolled spillways is the increased possibility of
pleasure boat accidents, because the drop in water surface
at the weir is difficult to recognize from upstream. This
hazard must be noted with proper warning signs and
devices. As riverflows increase, a pool elevation may be
reached where project navigation is suspended. In order
to mitigate the effect of upstream flooding at uncontrolled
spillways, locks are sometimes used as additional floodways by pinning the gates in an open position.
Fixed-crest (fixed-weir) dams are uncontrolled spillways.
For overflow structures this spillway can constitute the
entire navigation dam or a segment of it. This type of
dam is commonly utilized to “tie” gated dam sections into
the bank or abutment. The advantage of uncontrolled
spillways is their simplicity of both operation and maintenance; the dam structure contains no moving parts or
equipment that could be subject to malfunctioning. The
toe of the weir is subject to high-velocity, turbulent flows
which may necessitate significant scour protection
downstream from the dam to preserve the integrity of the
a. Structure types. Fixed-crest weir spillways normally utilized with navigation projects include concrete
gravity monoliths, concrete-capped or concrete-filled
cellular sheet pile structures, and rock fill dams with a
sheet pile cutoff wall incorporated in the fill. Additional
types of structures which may be utilized include rollercompacted concrete, reinforced-earth structures, I-walls,
T-walls, counterforted or buttressed concrete walls, bin
walls, and mechanically stabilized walls. If favorable
foundation conditions exist, tied-back or tied-down walls
may be appropriate.
EM 1110-2-2607
31 Jul 95
b. Crest shape. The shape of the fixed crest is
important. Under highly submerged conditions, the shape
has little impact on capacity. However, overflow sections
having significant head differentials will normally require
an ogee-shaped crest, energy dissipation structures, and
downstream channel protection. For this reason, many
fixed-crest spillways which are combined with gated
spillways to form the dam are constructed to a level
somewhat above normal pool (2 ft is common), so that
tailwater and headwater levels are approximately equal
when flow over the crest is initiated. This may allow
elimination of any energy dissipation structure.
c. Nonoverflow structures. Fixed-crest dams may
also be nonoverflow structures. These structures may be
earth or rock fill, cellular, concrete gravity, or any of the
above-noted types of walls. For additional information,
see EM 1110-2-1902, EM 1110-2-2300, and EM 1110-22503. Also, see Plates 10, 15, and 16.
5-5. Piers
a. General. Pier shapes and configurations affect the
hydraulic performance and discharge capacity of dams.
Piers for dams that have tainter-gated spillways must be
wide enough and long enough to accommodate trunnion
anchorages and girders, gate operating machinery, stairwells, recesses for unwatering bulkheads, and recesses for
second-pour concrete for side seal rubbing plates. Piers
for dams that have vertical-lift spillway gates need to be
wide enough and long enough to allow for vertical operating recesses and bearing surfaces for the gates, gate
operating machinery, gantry cranes, and recesses. Piers
for dams with roller spillway gates require widths and
lengths to accommodate the operating track (rack), bearing surfaces, gate operating machinery, and recesses for
unwatering bulkheads. Spillway bay widths, pier height,
and structural design requirements are also controlling
factors. Corps dams in existence have pier thicknesses in
the range of 8 to 15 ft. For piers, the most common and
usually most satisfactory design is a semicircular pier
nose shape. EM 1110-2-1605 provides more information
on spillway pier configuration.
b. Trunnion girders and anchorages. Most recent
tainter-gated dams designed and built by the Corps have
prestressed concrete trunnion girders which bear against
the downstream face of the pier and provide operational
and stationary support for the tainter gates. Usually the
girders are of the post-tensioned design. The larger
girders are usually cast in place, whereas the smaller ones
can be precast and then lifted into place by crane. The
girder should be located above most flood elevations.
However, submergence is sometimes allowed in the range
of 5 to 10 percent of the time. These girders have functioned satisfactorily on many Corps projects with very
little maintenance required and only a few instances of
nonserious slippage of the anchorages. Structural steel
trunnion girders have also been used successfully with the
prestressed anchorage system described below.
(1) The trunnion anchorage assembly is composed of
a grid of prestressing rods encased in steel pipes to allow
for later stressing. The assemblies slope down within the
pier toward the upstream face of the pier. Anchor plates
are provided at the upstream end of the prestress rods.
Bell- or ring-type anchors should not be used because it is
difficult to ensure concrete consolidation within these
devices. It is possible that the use of these anchorages
has been the source of observed anchorage slippage. The
assemblies are encased in a zone of high-strength concrete. The downstream end of the rods extends through
pipe sleeves in the trunnion girder, and the rods are
anchored on the downstream face of the girder. The rods
extend beyond the girder to allow attachment of a hydraulic jack for initial stressing and for future jacking to check
stress retention. After the initial stressing, a nonhardening
compound such as NO-OX-ID is pumped into the annular
space between the rod and the pipe sleeve to allow for
future restressing of the rods, if it is found necessary.
The downstream ends of the rods are coated with a rustpreventing compound and are enclosed in removable
covers. Many installations have used steel pipes that have
been grouted, in which case the anchors then become
bonded anchors. However, in locations where rods are
grouted, there is no opportunity to redress design concerns
at a later date. If the pipe enclosures are grouted, then
the grouting mix should be of a material that does not
expose the rods to hydrogen embrittlement.
(2) Pier anchorages are not required for vertical and
roller spillway gates because these gates transfer their
load into the piers through bearing surfaces in pier
(3) Figure 5-9 and Plate 8 show a typical prestressed
trunnion girder and anchorage. Further guidance for
layout and design is contained in EM 1110-2-2702.
c. Finite element modeling of structure anchor
forces. The prestressed trunnion girder and pier anchorage should be designed to resist all possible combinations
of tainter gate reactions. A conventional beam theory
usage will usually be satisfactory for preliminary design
of the pier. However, a finite element analysis of a girder
and pier section should be used to determine internal
EM 1110-2-2607
31 Jul 95
Figure 5-9. Prestressed concrete trunnion girder and anchor rods
EM 1110-2-2607
31 Jul 95
stresses in the prestressed or post-tensioned areas. Use of
the finite element analysis has shown that girder and pier
internal stresses are greater than those resulting from
calculations made using the straight-line conventionalbeam theory.
d. Operation and fabrication parameters which determine pier dimensions. Pier width, length, and height are
based primarily on the following operational features:
spillway discharge flow-shape requirements for nose of
pier, height of spillway gate in closed position, travel of
spillway gate to fully open position, trunnion girder location and trunnion anchorage requirements (for tainter
gate), machinery support requirements for spillway gate
operation, elevation of service bridge and service bridge
supports, recesses (slots) for upstream and downstream
maintenance bulkheads, dogging devices for bulkheads,
and interior personnel stairwell.
5-6. Miscellaneous Structural Features
a. General.
Various monoliths are designed to
satisfy hydraulic requirements, maintain foundation stability, provide foundation seepage control, and retain soil
where differences in grade elevations exist.
b. Stilling basins. Stilling basins are designed primarily to prevent erosion of foundation materials downstream of the dam, to furnish an acceptable seepage
gradient for permeable foundations, and to allow for
energy dissipation. Expansion joints separate stilling
basin slabs from each other, so each slab acts independently from other slab units. Sheet piles can be located
below the stilling basin at the perimeter to prevent piping
of foundation material due to seepage pressures. Stilling
basin slabs (or spillway aprons) are typically constructed
of reinforced concrete; however, roller-compacted concrete (RCC) slabs may be considered where reinforced
concrete elements are not required. Stilling basin slabs
are designed to withstand uplift loads acting over the
stilling basin length. For permeable foundations, the slab
thickness must be such that the submerged weight of the
concrete is sufficient to overbalance the uplift effect
resulting from the increase in static head below the
hydraulic jump. Drain holes should be considered for
relief of the pressure differential, provided the foundation
material will not erode through the drain holes and compromise the stability of the slab. Slabs on rock foundations are typically anchored to the rock with steel bars in
a grid configuration. If horizontal bedding planes are
present in the foundation rock, the upper rock strata will
be subjected to a net upward pressure, and the slab
anchorage should be carried to a depth below which the
upward pressure is balanced by the submerged weight of
the slab and rock. When energy dissipation is accomplished with the aid of baffle piers and plain or dentated
end sills, these structures are typically anchored to the
slab and designed for the impact of the water jet and
flowing ice or debris. However, such structures are
usually at sufficient depth below tailwater to keep them
submerged. The hydraulic loading may be estimated from
the total pressure on the projected area computed from the
maximum expected velocity of the impinging water (see
EM 1110-2-1605).
c. Training walls. Training walls are designed to
control flows upstream and downstream of the dam where
variations in the project features may cause unwanted
hydraulic effects. Flows through the dam may produce
eddies which cause adverse navigation approach conditions, damage to streambed and slope protection, and
sedimentation problems. Training walls are used to direct
intake or discharge flows. The elevation of the top of the
training walls is normally selected to prevent overtopping
at all but the highest discharges. Training walls are normally extended at a constant top elevation to the end of
the stilling basin. Adjacent project features and topography have a significant impact on training wall design
(see Plate 16). Training walls are typically constructed of
reinforced concrete with an inverted “T” cross-section
configuration, and are designed to withstand the differential load effects caused by variations in hydraulic profile
and the variation in sediment deposits that can occur on
each side of the wall. The estimation of these loading
conditions can be derived from hydraulic model studies.
See EM 1110-2-1603 and EM 1110-2-1605 for determining hydraulic forces (static and dynamic) on stilling
basin training walls.
d. Gate pier extensions. In accordance with EM
1110-2-1605, gate pier extensions are required to extend
into the basin to a position 5 ft upstream of the baffles to
prevent return flow from inoperative bays. The pier
extensions can be extended farther downstream if required
for stability. These extensions are required to ensure
adequate stilling basin performance. The pier extension
should be at least 1 ft higher than the tailwater used for
the single gate half or fully opened criteria. Pier extension width can be less than the main spillway piers.
e. End sill. A sloping end sill is normally required
to spread the flow for single gate operation. This slope is
normally 1V on 5H. The higher the end sill, the more
effective it will be in spreading the jet during single-gate
operation, but there are limitations. The higher end sill
results in shallower depths in the exit channel and
EM 1110-2-2607
31 Jul 95
possibly higher velocities over the riprap. The top of the
end sill should not be appreciably above the exit channel.
Also, the end sill should not be so high that it causes flow
to drop through critical depth and form a secondary
hydraulic jump downstream.
f. Grade separation walls. Grade separation walls
are required where transitions between differing grade
elevations cannot be achieved with a stable slope. The
wall may also be configured to function as a training wall.
Grade separation walls are designed as retaining walls
with proper consideration of the fully submerged condition. The required factors of safety are the same as for
the navigation lock and dam structures. Sedimentation
buildup may cause retained soil loading significantly
different from the constructed grades (see Plate 16).
Grade separation walls are typically constructed of
reinforced concrete with a “T,” or retaining wall, configuration. An unreinforced gravity wall RCC may be considered in appropriate cases.
g. Structural separation walls. Walls which separate
individual lock structures or which separate a lock structure from the dam gate or abutment structures will vary
considerably with the site and type of project selected.
The top of the wall will, at minimum, equal the normal
upper pool level plus freeboard (1 to 2 ft) but will most
generally be equal to the top of the lock walls to allow
proper navigation during higher river stages. See Plate 1.
5-7. Special Design Considerations
a. Low-flow and water quality releases. Provision
for sluices as part of the main spillway or a separate
outlet works to accomplish low-flow or multilevel releases
should be designed according to EM 1110-2-1602.
b. Fish passage facilities. Most fish passage facilities
are located at the dams on the Columbia and Snake
These structures are normally ladder type
structures, fish screens, sluiceways, etc. See Plate 12 for
typical fish ladder locations at a lock and dam project.
c. Ice control methods. It is desirable and often
essential to continue operation of navigation dams and
spillways during winter (see EM 1110-8-1(FR)). Traffic
may be curtailed or even stopped on the waterway, but
provision must be made to pass winter flows and to
handle ice during winter and at breakup. Designers must
consider ice passage procedures, possible ice retention, ice
forces on the structures, and icing problems leading to
blocking of moving parts or simply excess weight. Provisions to move ice past or through dams have been many
and varied and none have met with perfect success. At
some locations, it is preferable to retain the ice in the
upstream pool, while at others an ice-passing capability is
necessary. Regulating gates on a dam structure can be
used to pass ice and debris by either underflow or overflow. In the first case, the gates are opened sufficiently
wide to create enough flow that accumulated ice and
debris are pulled from the upper pool to the lower pool,
to be carried from the structure by the current. The magnitude of opening for successful operation depends on
local conditions and experience; it is usually one-third to
fully opened gate, depending on tailwater level. Hydraulic model tests give some indication of the required opening for new structures. One of the dangers of this
operation is that it often causes downstream scour holes.
To prevent occurrence of scour, proper scour protection
and/or energy dissipation must be provided. Spillway
openings should be as wide as practicable to minimize
arching of ice across the openings. The primary factor
controlling ice passage appears to be the velocity of the
approaching ice. When the velocity is great enough, the
floes are broken and pass through spillway bays. Passage
of ice through a submerged outlet requires sufficient
velocity to entrain the ice into the flow. Therefore, to
maintain pool during periods of low flow, ice may be
passed over the tops of gates; however, this has met with
only limited success under certain ice and flow conditions.
At low flows ice can be passed with one or more gates
open at a time and arching broken by alternating gate
openings. Physical models of ice control methods for
specific projects can be made in the Ice Engineering Laboratory at CRREL. EM 1110-2-1612 provides additional
information on ice control methods.
EM 1110-2-2607
31 Jul 95
Chapter 6
Maintenance and Emergency Closure
loss of the navigational pool. Serious accidents are more
likely to occur during high-water periods than during low
water. Designers and operators should be aware of those
conditions likely to cause serious damage to the structure
in case of collision.
6-1. Maintenance and Emergency Closure
d. Spillway gate positions. For spillway gates, the
two positions presenting the least potential for damage at
many projects are the fully raised position, particularly if
this is higher than barges or tows passing through gate
bays, and the fully closed position. A particularly vulnerable position is that of the lips of the gates slightly below
or slightly above water level. In a rising river situation,
with consequent increasing gate openings, it should be
required operating procedure that the gates be raised to a
position above the highest expected water level.
Designers may find it prudent to include remote operating
capability to permit quick action on the part of operators
during emergencies. In developing an operating plan, the
responsible individuals may want to require a staggered
gate operation in order to reduce the potential for a current concentration approaching the spillway (e.g., Gates 2,
4, and 6 should be raised one increment followed by
raising Gates 1, 3, and 5).
a. General. Accidents involving the dam are usually
caused by tows that have “broken up,” resulting in barges
being lodged in gate bays and/or wrapped around dam
piers. Since bulkheads cannot be placed until the damaged barges are removed, and only one gate bay at a time
can be closed using emergency closure, the practicability
of bulkhead use and corresponding benefits are limited.
The consequences of inoperable navigational dam gates
may include loss of pool or higher than normal induced
stages. Either event may involve significant economic
losses. Measures to allow maintenance of dam gates and
operating machinery, with analysis of the costs of providing emergency closure and the corresponding benefits
(with water potentially flowing uncontrolled through a
gate bay area), should be addressed in the design documents. Since access to spillway gates is usually via the
closed lock gates, a contingency plan should be developed
for access to spillway gates so closure can be made in
case of an accident.
6-2. Maintenance of Gated Nonnavigable Spillway Structures
b. Spillway capacity. Limited gate availability operation occurs when one or more gate bays are closed for
maintenance or repair work on the gates. The most
important consideration in this operation is that the
remaining spillway capacity should be sufficient to handle
anticipated high flows without causing detrimental
increase in upstream stages. If feasible, repair and maintenance work should be scheduled during low-flow
periods. On some projects, locks could be used as floodways should an emergency develop during repair work if
they have been designed and equipped for this purpose.
a. Location. Maintenance of this type of structure is
normally accomplished with the combined use of an
upstream maintenance or emergency bulkhead and a
downstream maintenance bulkhead (if necessary) to allow
unwatering the gate (bay) during maintenance activities.
Emergency closure equipment should be stored at the dam
site. Downstream maintenance closures may be stored at
the site or at a central location if used for several dams.
Installation can involve the use of hoist cars, cranes, stiffleg derricks, derrick boats, and in limited instances,
c. Emergency closure. Although emergency-closure
bulkheads or vertical-lift gates are normally located
upstream of the spillway gates, several instances of barges
becoming lodged at the bulkhead location have precluded
installation of the emergency closure. Consideration
should be given to locations either upstream or downstream of the service gate to provide optimum protection.
Potential for serious damage to a navigation dam exists
due to the presence of navigation traffic. Appendix C
includes descriptions of three major accidents that are
representative of what can occur (Markland in 1967 and
Maxwell in 1985 and 1990). In the case of collision,
damage can vary from inconsequential to major, including
b. Maintenance closure types. Since maintenance
closure structures are for use when a spillway bay is to be
unwatered for inspection or maintenance, they are
designed only for static heads and cannot be installed in
flowing water. Appropriate pier recesses and sills must
be provided to allow for installation of these closure
structures. The maintenance closure structure selected for
use at a particular dam will depend on the type of gate
and associated piers and sills, whether or not there are
bulkheads available for use in the waterway system, what
equipment or methods are readily available for use in
transporting or installing the bulkheads, and economy and
EM 1110-2-2607
31 Jul 95
reliability. The types of maintenance closures that have
been used most are sectional bulkheads, dewatering boxes,
vertical-lift gates, Poiree dams, and needle dams. Figure 6-1, a-e, shows these types of maintenance closures.
Poiree dams and needle dams are generally not recommended because of the need to use divers to install them
and the length of time required for the installation.
Dewatering boxes are suitable only for wicket dams.
(1) Sectional bulkheads. This type of closure structure can be constructed of welded structural steel or
riveted aluminum material. The limiting height of each
individual section is governed by the handling capacity of
the available handling equipment. Lifting beams or other
provisions must be included. High-strength steels or
aluminum can be used to lessen the weight of these bulkhead sections. Riveted aluminum bulkheads are in use on
the 110-ft-wide lower Ohio River tainter gate structures
because the bulkheads have to be transported from one
dam to another and installed by a limited-lifting-capacity
floating crane (derrick boat). These bulkheads are for use
only downstream of the tainter gates; they are also used
downstream at the locks. The maintenance bulkheads
consist of trusses and skin plates or girders and skin
plates. Wheels are not furnished on the ends since the
bulkheads are installed in static water. The water load on
the bulkheads is transferred to the pier walls at the pier
wall recesses, and the sill carries only the dead weight of
the bulkheads. Sectional bulkheads are used more than
any other type of maintenance closure for ease of installation by floating plant.
(2) Poiree dams. Poiree dam closures are constructed
of structural steel and are composed of a series of vertical
A-frame truss members which are set and pinned by
divers into an anchorage casting or shoe embedded in the
concrete sill. When these members are positioned and
properly stabilized, panels are placed on the upstream face
of the A-frames. These panels are usually set by a derrick boat with the help of divers to position the underwater parts. Usually, one Poiree dam will be utilized for
several dams in a waterway system. The water load on
the Poiree dam is transferred by the A-frames to the concrete sill through the embedded anchorages. The Poiree
dam arrangement is generally not selected for new designs
because better, safer options are now available.
(3) Needle dams. Needle dams are constructed of
structural steel and are composed of a horizontal beam or
girder or triangular truss supported by the piers at each
end and a series of needles or vertical panels that rest
against the support at the top. These needles are positioned by a diver into the proper location on the concrete
sill at the bottom. Thus, a portion of the load is transferred into the pier recesses at the top, and a portion of
the load goes into the sill from each individual needle or
panel. A pipe or similar object is positioned at each of
the abutting edges of the vertical panels to better seal the
opening. For further watertightness, cinders are sometimes used. This type of closure is more suitable for
narrow gates because the needle beam weight and configuration become limiting factors. Needle dams are adaptable for either upstream or downstream closures. As with
the Poiree dam, this arrangement is generally not used for
new designs.
(4) Floating closure.
Floating closure structures
have not been used extensively, but where they have been
used they have functioned well. One such caisson is used
for locks on the Columbia and Snake River systems.
Another floating caisson is in use for 110-ft-wide locks on
the Tennessee and Cumberland River Waterways. The
structural steel caissons are composed of watertight compartments which allow the towing of the floating caisson
from one lock to another. The compartments are filled
with water so that the caisson can be positioned in
recesses in the lock wall and sunk in place across the lock
chamber. Compressed air is used to remove the water
from the caisson and return it to floating capability. In
view of the success of these facilities, a floating caisson is
(5) Braced-box cofferdam.
A large braced-box
cofferdam, constructed and installed as two halves (to
facilitate use of an existing 100-ton derrick boat), was
successfully utilized to repair the Ohio River Lock and
Dam 52 temporary lock (cellular/concrete) miter gate sill.
(6) Use of emergency closures for maintenance
closures. At dams where an emergency closure structure
is provided upstream of the service gate, the emergency
structure can also be used for maintenance unwatering.
Additionally, recesses can be provided in the piers for
installation of sectional bulkheads similar to the ones used
for unwatering maintenance downstream of the gate.
6-3. Emergency Closure of Gated, Nonnavigable
Spillway Structures
Where a large level of damage could result from water
flowing free through a dam gate bay, an emergency
means to quickly stop the unrestricted flow should be
studied. This unrestricted flow could happen if the gates
were rendered inoperable or knocked out due to being
rammed by a tow.
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Figure 6-1. Maintenance closures
EM 1110-2-2607
31 Jul 95
a. General. The following conditions must be considered and evaluated in determining whether or not an
emergency closure structure is necessary: consequences
of loss of pool (such as effects on water intake and outfall
structures and docks and towing industry losses); economic losses to shipping interests due to halt of river
traffic; possible flood damage and danger to people downstream; and consequences to channel banks in pool due to
sudden drawdown. If incorporation of emergency closure
is found to be economically justified, all elements of the
emergency closure structure, including the handling equipment and machinery and the structure itself, should be
ready for use 24 hours a day. Proper maintenance of all
elements is necessary, along with periodic practice installation of the closure. Reliability and a fast installation
time are a must. The types of emergency closures that
have been used are stacked bulkheads and vertical-lift
b. Overhead stacked bulkheads.
(1) General. The stacked bulkhead arrangement has
proven to be the most dependable and reliable for emergency closure purposes. Most major dams built in recent
years have utilized this concept successfully.
sectional bulkheads (stop logs) have end rollers and are
made up of trusses and skin plates. The lifting and installation equipment is usually very expensive and consists of
either a bridge crane (hoist car) or a traveling gantry
(2) Bridge crane (hoist car). The bridge crane (hoist
car) is sometimes referred to as a locomotive crane. See
Plate 9. Most of the tainter-gated dams on the Ohio
River and the new Melvin Price Locks and Dam on the
Mississippi River use a bridge crane for handling the
bulkheads. At many of these projects, the spillway bays
and the lock width are both 110 ft wide so that the emergency bulkheads can be used to close off either an individual 110-ft-wide spillway bay or one 110-ft-wide lock
chamber. Thus, the service bridge is laid out so that it
and the bridge crane and bulkheads serve both the locks
and dam spillways. An auxiliary crane is located on top
of the bridge crane for use in handling small loads during
maintenance or unwatering activities.
(3) Detailed bulkhead installation procedure. Past
experience and model testing by WES have shown that
bulkheads cannot be lowered safely one at a time in flowing water. Therefore, the stacked bulkhead system was
developed so that the flowing water never goes over the
top of the bulkheads.
(a) The Ohio River and Mississippi River Dams
mentioned above have a hoist car mounted on rails on a
service bridge which serves both the dam spillway and the
locks. Normally, the bulkheads are stored singly over the
spillway bays on retractable dogging devices on the service bridge piers. The required lifting beam will be
stored on one of the dogged bulkheads. The hoist car can
travel the full length of the service bridge but can carry
only the lifting beam and one bulkhead while traveling.
(b) The following example details the installation
procedure for three bulkheads; however, the same
sequence of activities would be true for any number of
bulkheads. The hoist car will pick up one bulkhead with
a lifting beam and move it to the location for unwatering;
at this location it will be placed on the dogging device.
The hoist car will then move with the lifting beam and
pick up another bulkhead and move back and place it atop
and latch it to the first one. The two will then be raised
enough to retract and reposition the dogging device so
that they can be lowered onto it. The hoist car moves
with the lifting beam to get a third bulkhead, which is
placed and latched to the other two, and then lifts the
three bulkheads and lowers them as a unit into the flowing water after the dogging device has been retracted. In
this manner, the flowing water is stopped without being
allowed to flow over the top of any of the bulkheads.
After the bulkheads have served their purpose and the
spillway gate is closed, the bulkheads are removed one at
a time in a balanced (static) pool situation by the hoist car
and returned to their individually dogged (stored) position.
c. Vertical-lift gates. Vertical-lift gates may also be
utilized as an emergency closure--especially on dams that
have vertical-lift spillway service gates which are installed
and removed by a traveling gantry crane. These gates
would be similar to the vertical-lift service gates described
in paragraph 5-2c.
6-4. Maintenance of Gated, Navigable Spillways
Maintenance of gated navigable spillways must be accomplished under somewhat different conditions than that of
nonnavigable spillways. The absence of intermediate
piers generally limits the type of closure to floating bulkheads, rigid-box closures, Poiree dams, separate duplicate
gates, collapsible A-Frame, and, for low-head applications, removable-post and stop-log installations. The
gated navigable pass spillway is generally less vulnerable
to navigation accidents than nonnavigable spillways
because the gates are lowered during high water events,
EM 1110-2-2607
31 Jul 95
which produce conditions most likely to lead to an
6-5. Emergency Closure of a Gated, Navigable
Also, since a damaged navigable pass gate is usually
comparatively small, and redundant operating procedures
are easily accommodated, an emergency gate for this type
of spillway is generally excluded.
As stated earlier, if flow conditions and redundant
(backup) systems of operation are incorporated (and loss
of pool is a low-risk occurrence), then emergency closure
may not be required. An example of this is included in
the Olmsted project. At this project, all of the dam
wicket gates will be required to be up only during a very
infrequent low-flow event. Damage to a significant portion of the dam can be tolerated (temporarily) by shifting
regulation from damaged gates to unused (down) gates.
Risk of loss of pool is low, and repair may then be
accomplished with more favorable upper and lower pool
conditions. Additionally, the wicket gate operating systems may be switched over to the adjacent bank of pumps
and motors in the event of failure of one system.
a. Machinery. Machinery for gated navigable spillways, which can be incorporated in a dry gallery in the
dam sill, is much easier to maintain than machinery for
nonnavigable spillways. Also, because navigable pass
gates are generally smaller, gate and operator units (cylinders) which can be easily removed and replaced by spare
units are desirable. This shortens exposure time and
lessens the difficulty of normal maintenance by allowing
offsite rehabilitation of the major units. Use of various
caissons, floating bulkheads, and gates for maintenance of
gated, navigable spillways is similar to that described for
nonnavigable spillways, with the exception that spillway
piers are absent. The procedure utilized for maintenance
will rely on a floating plant, which must be included in
the maintenance scheme unless duplicate gates are used as
backup to the service gates.
b. Procedure. At the Olmsted Locks and Dam project, the procedure for performing maintenance will be
accomplished with the use of a one-piece shutter box,
which allows work on one, two, or three gates at one
setting. The upstream shutter box will be placed any time
work is required on a wicket. With the box in place, any
“in-the-wet” work can be done. The water level within
the box will be the lower pool level. A brace will be
provided to prop a wicket vertically, if desired. The
downstream shutter box is required when it is necessary
to dewater the area. At the top, a truss may be provided
to carry the loading.
c. Maintenance. Maintenance of the hydraulic system
will be performed by removing the entire hydraulic
system (cylinders, flexible lines, bearings, cover seal,
rubber boot, etc.) from the precast frame in the sill. The
unit will be removed by personnel on the work boat and a
new or refurbished one inserted. This will allow the unit
to be refurbished for future use in the maintenance shop
as time permits. The hydraulic pumps and valves will
have shutoff valves and unions to allow removal of any
component from the dry gallery. The hydraulic lines
which penetrate the gallery walls will be located inside a
sleeve for replacement when the hydraulic cylinders are
removed. The wickets will be pinned in place, and the
hurters will be bolted down.
These items will be
removed by the personnel on the work boat.
a. Crane operation. The wickets are also designed
to be raised and lowered by a crane located on a work
boat. In addition to raising and lowering a wicket if the
hydraulic system is inoperable, the crane will cut away
large debris that collects on the dam by means of a
hydraulic shear attachment on its boom, set the shutter
boxes, and remove components of the navigable pass such
as wickets, cylinders, and hurters. The wickets will use
the same basic principle of prop and hurter mechanism
used at Locks and Dams 52 and 53 on the Ohio River.
The major addition to the prop is the installation of a
“weak link” to be used to help prevent serious damage to
the wicket during a navigational accident. The prop will
be designed to withstand ice and impact loading but to
fail and allow the wicket to fall when impacted by a load
slightly below the yield strength of the wicket.
b. Further requirements. If emergency closure of a
gated navigable pass spillway is required, a floating bulkhead structure with adequate guide and anchorage must be
provided, or a separate set of gates must be provided with
the appropriate lengthening of the dam sill to accommodate these gates (which are generally upstream of the
service gates).
6-6. Maintenance and Emergency Closure of a
Fixed-Crest Spillway
Special provisions for fixed-crest spillways are not normally required because of the low risk and low maintenance requirements.
EM 1110-2-2607
31 Jul 95
6-7. Floating Plant
a. The floating plant necessary for installing the
upstream and downstream spillway gate bay unwatering
bulkheads for either maintenance or emergency purposes
may be composed of the following:
(1) Derrick boat with suitable capacity and reach.
(2) Work barge to transport sectional bulkheads from
storage location to dam spillway.
rings, check posts, and line hooks on each pier, and
armored mooring holes through the piers to use to anchor
lines from the floating plant vessels. For emergency
situations, such as free flow through a spillway bay when
a spillway gate cannot be closed for some reason, it will
be necessary to provide additional anchorage facilities
upstream of the dam. These facilities can include deadmen, mooring cells, or pylons on the bank or in the water,
and mooring posts on the upper lock wall--all to accommodate floating plant anchor lines.
6-8. Galleries, Adits, and Openings
(3) Work (shop) barge with all necessary equipment
such as anchor lines, tools, paint, ladders, sand
blasting equipment, safety harness, etc.
(4) Personnel barge with clothing-change facilities for
special body covering and footwear plus eating
and break accommodations, if not provided on
shop barge.
(5) Small boat with outboard motor for transporting
personnel to and from bank to work barges and
personnel barge.
(6) Work flat (approx. 8 ft × 12 ft).
b. To stabilize all the above floating plant vessels in
suitable locations above and below the dam in flowing or
quiet water situations, it is necessary to furnish mooring
Normal periodic maintenance and inspection of spillway
gates, when the gates are not unwatered, can require providing a means for operating personnel to access certain
parts of the gate. This is particularly true for a tainter
gate. The dam pier will usually contain a stairwell
extending from the service bridge level down to the
trunnion girder level. An opening from this stairwell to
the trunnion girder on the downstream face of the pier
will provide personnel access for greasing the trunnion
pin and for inspecting the trunnion anchorage and the
trunnion girder. Some tainter gate arms also have handrails for personnel use in accessing the gate body. Also,
an access opening may be provided from the stairwell to
the spillway face of the pier for wire rope greasing and
inspection and gate inspection. For double-skin plate
gates and gates with cover plates, this type of opening can
allow access to the interior of the gate.
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31 Jul 95
Chapter 7
Seepage Control Measures and Features
c. Seepage analysis. Seepage analysis will generally
be required. Detailed information on seepage analysis and
layout details of seepage control systems are contained in
EM 1110-2-1901.
7-1. General
d. References. Detailed information on foundation
grouting, planning, and specification writing is contained
in EM 1110-2-3506 and in Guide Specifications for Civil
Works Construction.
Unless properly treated, seepage of reservoir water
through a dam foundation and abutments can present
serious problems regardless of the type of foundation-rock, soil, or piling. The primary purpose of controlling
the seepage of water through a dam foundation is to
prevent the foundation material from piping and washing
away, which could result in structural failure due to loss
of support. A secondary purpose of controlling seepage is
to reduce foundation uplift pressures. Impervious (clay)
blankets and cutoff walls, in particular, lengthen the seepage path and thereby reduce uplift pressures. However,
where foundation drains are provided, it has been Corps
practice in the design for sliding and overturning stability
to either disregard the benefit of the drains or consider the
drains only partially effective in limiting uplift pressures.
However, maximum possible uplift values should be used
for checking foundation pressures and relief of pile loadings. Piezometers have been used very effectively in
some cases to identify problems with existing seepage
control systems. When filters are placed under a dam to
relieve excess uplift pressures, they are of particular benefit to the stilling basin slab design because the slab without the filter would need to be anchored or of massive
thickness. To attenuate, control, collect, and/or direct the
seepage discharge, careful and thorough geotechnical and
hydraulic studies and evaluations must be made, and
proper cutoff (control) features must be designed.
a. Foundation seepage.
The particular seepage
problem for soil foundations and pile foundations--as well
as some rock foundations which have solution channels,
rock jointing, and cavities--involves piping out the foundation material. To counteract this piping, seepage control can be accomplished by a site-specific cutoff method
featuring foundation grouting and drainage, steel sheet
piling cutoff walls, impervious cutoff walls (trenches),
concrete cutoff walls, slurry trench cutoffs, or an upstream
impervious blanket.
b. Abutment seepage. To prevent the bank from failing and the stream from possibly bypassing the dam,
treatment of the dam abutments should include cutoff
walls, a competent bank tie-in structure, and bank slope
7-2. Foundation Grouting and Drainage
a. Dams founded on rock.
(1) It is customary to grout and drain the foundation
rock of concrete gravity dams. This practice works well
for defective as well as sound formations. A wellplanned, well-executed grouting program will not only
reduce seepage through the rock but may also disclose the
presence of unsuspected weaknesses in the foundation,
thus improving any existing defects. Such a program,
therefore, provides an added safety measure and ensures
against future trouble.
(2) The most common design consists of a single
line of grout holes located near the upstream face of the
dam, drilled at five-foot centers and to a depth ranging
from four-tenths to six-tenths of the maximum hydrostatic
head on the base of the dam. A corresponding line of
drainage holes is drilled a few feet downstream from the
grout curtain and to a depth roughly two-thirds to threequarters that of the cutoff curtain. This grout curtain may
be constructed by drilling and grouting from a gallery
within the dam, from the top of a specified thickness of
concrete, or from the top of foundation rock. If a gallery
is provided, then a series of drain holes will be drilled
from the gallery and located just downstream of the grout
curtain. See Figure 7-1 for layout and details of a grouting gallery with foundation grouting holes and foundation
drain holes. It is essential to control the grouting pressures so that splitting and lifting of rock will not occur.
Thin-bedded rocks are especially susceptible to damage
by excessive grout pressures.
(3) When a stilling basin (also referred to as an
“apron” or “bucket”) is founded on rock, drain holes
should be provided in the rock with a collector and discharge system at the founding level for partial relief of
the pressure differential.
A typical stilling basin
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Figure 7-1. Typical grouting and drainage curtain
EM 1110-2-2607
31 Jul 95
foundation drainage system and anchorage layout are
shown in Figure 7-2.
b. Dams founded on soil or piling. Soil or pile foundations should have upstream and downstream cutoff
walls (usually steel sheet piling) under the structure
proper plus a cutoff wall underneath the downstream end
of the stilling basin. These cutoff walls prevent piping of
the foundation material due to seepage pressure. Every
effort should be made to provide a reliable drainage system underneath the dam proper and the stilling basin to
ensure pressure relief between the cutoffs. Plate 2 shows
details of an underdrain system for soil-founded Dam
No. 4 on the Red River in Louisiana (Vicksburg district).
This system uses 6-in.-diam stainless steel well screen
encased in a 2-ft-thick filter material, combined with
access manholes, for relief of excess foundation uplift
pressures which build up in the foundation. PVC (polyvinyl chloride) pipes connect the manholes to equalize the
pressure in the system, and gate valves are provided so
that the manholes can be unwatered to allow maintenance
of the system.
7-3. Impervious Cutoff Walls (Trenches)
These compacted backfill trenches are constructed from
the base of an earth dam structure through the upper
pervious layers down to impervious soil layers or to bedrock. The cutoff trench is an extension of the impervious
zone of the dam proper. See Plate 10 for details.
7-4. Concrete Cutoff Walls
a. Shallow cutoffs. Shallow depth cutoffs may be
constructed where shallow trenches can be excavated and
backfilled with concrete. This cutoff method can be
applied when navigation dam piers are spaced at a clear
distance between piers as wide as the navigation lock. In
this case, a dam pier founded on rock may not require a
transverse width (for stability) as wide as the pier spacing,
and a segment of the spillway section could span between
the pier bases. The spillway segment could be supported
by the dam pier bases instead of being founded on rock,
if overburden material exists. A concrete cutoff wall
extending from the spillway segment base down to rock
may be feasible. See Plate 8.
b. Intermediate depth cutoffs. An intermediate depth
(up to about 80 ft) cutoff can be achieved by the slurry
trench method. As the trench is excavated by conventional equipment -- backhoe, dragline, etc. -- the bentonite
slurry is introduced to support the sides of the excavation.
When the excavation reaches the design depth, impervious
material is placed under controlled conditions to establish
the cutoff. For major, permanent structures, the slurry
should generally be displaced with tremie concrete.
c. Deep cutoffs. When concrete cutoffs need to
extend to a great depth below either a concrete or an earth
dam structure, a 2.5- to 3-ft-wide excavation is drilled by
special equipment and the excavation walls supported by
bentonite slurry, which is displaced when the concrete is
placed by the tremie method.
7-5. Sheet Pile Cutoff Walls
Continuous steel sheet piling cutoff walls are used for
soil-supported and pile-supported concrete dam structures.
The piling should be used upstream and usually also
downstream and should be embedded 1 to 2 ft into the
base of the concrete at the top. The piling will be driven
to a depth that satisfies the seepage cutoff requirements
indicated by analysis. See Plate 2 for a typical steel sheet
pile cutoff. The following discussion will provide guidance for the use of cold-formed, Z-type steel sheet piling
as an alternative to hot-rolled, Z-type steel sheet piling.
This type of piling is used for straight wall installations
where beam strength (bending) is a primary design consideration. While the sheets are required to interlock, no
supplier has ever warranted a specific interlock tension
value. The hot-rolled piling and the cold-formed piling
have markedly different interlock configurations, as
depicted in Figure 7-3.
a. Section stability. While neither the hot-rolled nor
the cold-formed shapes have been sized to meet any
width-depth or width-thickness criteria, it appears that the
configuration of the cold-formed sections results in section instability. Currently, there exist no criteria for section stability; therefore, in applications where high stresses
are expected, appropriate section stability checks should
be made.
b. Seepage. The loose fit of the cold-formed sheets
can result in greater seepage than occurs with hot-rolled.
However, with time, the interlocks may silt-in and provide
adequate control of seepage. Analyses considering the
magnitude of seepage and the potential for silting-in
should be performed to determine if the cold-formed
sheets are acceptable.
c. Installation. Problems have been reported regarding the tendency to drive the cold-formed sheets out of
interlocks in areas of hard driving. Also, due to the loose
fit, vertical plumb in the plane of the wall is difficult to
EM 1110-2-2607
31 Jul 95
Figure 7-2. Stilling basin drainage and anchorage
EM 1110-2-2607
31 Jul 95
Figure 7-3. Steel sheet piling
EM 1110-2-2607
31 Jul 95
d. Corps of Engineers specifications. Guide Specification CW-02411 allows for the use of heavy-gauge coldformed piling as an alternative to hot-rolled steel sheet
piling but gives the following recommendations:
(1) Hot-rolled steel sheet piling sections. Hot-rolled
steel sheet piling sections are suitable for applications
where interlocked joint strength in tension or section
stability is a primary design requirement. Section stability
(biaxial stress) is a consideration in highly stressed applications only.
(2) Hot-rolled, light-duty steel sheet piling sections.
Hot-rolled, light-duty steel sheet piling sections and coldformed steel sheet piling sections are suitable for averagedepth applications such as trench sheeting and bulkheads
in moderate water depths. They are not suitable for applications where they are subjected to high concentrated
wale loads or where interlocked joint strength in tension
or section stability is a primary design requirement.
(3) Cold-formed, light gauge steel sheet piling sections. Cold-formed, light gauge steel sheet piling sections
are suitable for applications with a required minimum
sheeting thickness of 0.250 in. or less, low bending and
corrosion resistances, and minimal required interlocked
joint strength in tension. The corrosion resistance of light
gauge sheet piling can be increased by applying a protective coating.
e. Conclusions. Since the use of a different type of
piling will depend on site-specific conditions, each Corps
office needs to make its own decision on whether or not
to use the cold-formed steel sheet piling. The decision
should be based on site-specific foundation data, design
requirements, and the importance of obtaining the best
possible “in-place” assembly to prevent excessive amounts
of water from passing through the interlocks. In locations
where the piling is installed in a pure bending design
requirement and where excessive flow of water through
the interlocks with undesirable displacement of material is
not a controlling factor, the cold-formed piling should
perform equally as well as the hot-rolled piling (assuming
the equivalent section properties).
7-6. Upstream Impervious Blanket
An upstream impervious blanket will frequently be advantageous for soil and pile founded dams, as it increases the
length of the seepage paths and thereby reduces uplift
pressures under the structures and the potential for seepage problems. The blanket will usually be of clay material (rather than concrete) for purposes of economy. An
impervious membrane, in lieu of a clay blanket, is not
recommended because of the high risk of punctures and
tears. Typically, the blanket will be a minimum of 5 ft in
thickness, and will extend upstream as necessary for seepage control and extend as necessary to the adjacent channel slopes. To account for potential separation between
the blanket and structure, an impervious membrane, with
laps to allow lateral movement without tearing the membrane, is attached to the face of the structure and embedded into the blanket. Refer to Plate 11 for details.
EM 1110-2-2607
31 Jul 95
Chapter 8
Channel Protection
8-1. General
Stabilization of banks and protection of the stream bed
will usually be required for the channel at the dam site.
In addition, channel realignment and/or training structures
may be required. The specific types of channel protection
and stabilization will depend on water velocities, wash
from waves, water level fluctuations, soil characteristics,
stream alignment, sediment transport, wind velocities, and
navigation approach conditions. This chapter will outline,
in general terms, the overall requirements for channel
protection. More details and guidance are contained in
EM 1110-2-1611.
8-2. Erodible Slopes and Stream Bed
a. Erodible slopes. When geotechnical investigations
and studies indicate that the stream banks at the dam site
will not be stable under project operating conditions, it
will be necessary to protect and stabilize these slopes so
that they will not erode and displace into the stream or
fail internally.
b. Stream bed.
The stream bed immediately
upstream and downstream of a concrete dam will require
protection to prevent displacement of bed material that
could undermine the structures and result in failure of the
dam and/or appurtenant structures.
c. Scour protection during construction. Each construction scheme must be carefully analyzed to ensure that
scour protection is provided where necessary. Successful
protection has consisted of timber (lumber) mattresses or
riprap, both with and without filter blankets, depending on
the soil types and flow conditions.
Physical and
numerical models have been useful in developing scour
protection designs.
For cofferdams within the river
channel, the riverward corner of the cofferdam is usually
the critical point of scour potential. Wing extensions are
sometimes provided to minimize the scour potential.
8-3. Typical Materials
a. Slope protection materials. For channel slope
protection, the following materials are used most often:
riprap stone placed on either a sand-and-gravel filter blanket or a filter cloth, soil-cement paving, concrete paving,
steel pile cells filled with stone, and articulated concrete
mattresses. To be effective, the slope protection system
material must be sized with a designed thickness and must
be provided with drainage blankets or pipes so that water
can pass through the protection without displacing the
underlying support material. In most cases, the type of
material chosen for slope protection will depend on the
availability of suitable natural material in the project area,
which is likely to be least costly.
b. Streambed protection materials. For streambed
protection, the following materials are used: graded
stone, derrick stone, concrete paving, trench-filled (stone)
revetment, and lumber mattress. The materials chosen for
streambed protection will depend on their availability and
on specific design and maintenance requirements during
the life of the project.
8-4. Dikes
Dikes for bank protection and stabilization can consist of
stone, timber pile clusters, or piling with stone fill. These
dikes are designed to divert currents away from the bank
or improve the alignment and velocity of the currents
along the bank. Training dikes can be very beneficial in
controlling sediment deposition in the upstream and
downstream lock approaches and in diverting spillway
discharges away from the lower lock approach. See
Plate 7. Wing dikes (also referred to as wing dams or
spur dikes) placed approximately normal to the channel or
lock approach have proven to be suitable for these
Various types of dikes are described in
EM 1110-2-1611.
8-5. Upstream Channel
a. Channel slopes. Just as the bank slope must be
designed for stability, so the slope surfaces must be protected. Stone riprap on a sand-and-gravel blanket or on
filter cloth can be used. Other forms of slope protection,
such as articulated concrete mats, concrete paving, and
soil-cement blankets, have also been used. The type of
protection material chosen will depend on economy of
usage and the ability of the material to satisfy design
requirements for the life of the project with minimum
maintenance costs.
b. Streambed. A low-head navigation dam will
usually require streambed protection upstream of the
spillway for a minimum distance equal to the head on the
spillway crest. The protection is usually stone; however,
concrete aprons have been used. Refer to EM 1110-21605 for details. High-head dams will not usually require
upstream streambed protection because of the height of
the spillway crest above the streambed. The upstream
EM 1110-2-2607
31 Jul 95
streambed of a navigation dam with a ported upper guide
wall adjacent to the dam spillway will require stone protection at the ported openings to prevent scour of the bed
material due to water velocities caused by spillway discharges. This bed protection is especially important for
soil-supported, pile-supported, or caisson-supported guide
walls. Refer to Plates 3, 5, and 17.
8-6. Downstream Channel
a. Channel slopes.
Treatment and protection of
downstream channel slopes will be similar to that for
upstream channel slopes. However, the thicknesses and
the extent of this protection will usually be determined by
using the results of the hydraulic model test. Refer to
Plates 3 and 5 for more details.
b. Design conditions for streambed downstream of
gated spillway.
The streambed area immediately
downstream of the stilling basin will require a special
hydraulic investigation to determine the amount and
extent of streambed scour protection needed to counteract
the forces created by the spillway discharges. The spillway gate operation design conditions are outlined in
ER 1110-2-1458. For a streambed composed of sound
rock, no protection may be needed. However, for a
readily erodible streambed, several extensive layers of
graded rock may be required. Gradation layers, size of
stones, and extent of protection are usually designed by
hydraulic engineers using guidance contained in
EM 1110-2-1605. EM 1110-2-1605 covers scour protection experiences at existing Corps projects and repair
recommendations for these projects. EM 1110-2-1601
and EM 1110-2-1901 contain further design information
relative to riprap and filter designs.
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31 Jul 95
Chapter 9
9-1. General
This chapter contains discussion and guidance on loads
that can normally be expected to be imparted to a dam or
appurtenant structure. Loads described in this section are
those resulting from construction activity: lateral earth
pressures; hydrostatic, including uplift and hydrostatic
pressures; water above or contained within a structure;
dynamic forces from impact or seismic activity; line pull
forces; wind, wave, ice, and debris forces; gate, bridge,
crane, and bulkhead forces; pressures on sheet pile cutoff
walls; forces in monolith joints; superstructure weight;
and thermal stresses.
based on the heaviest piece of equipment likely to be
placed on the fill during construction.
e. Seepage forces resulting from adjacent dewatering. When the newly completed or existing structure is
used as a portion of the dewatering cofferdam, the adjacent dewatering causes seepage forces to act on these
structures and the foundation materials below the structures. Research is currently underway at WES to evaluate
the magnitude of these forces at the Mel Price Locks and
Dam project.
f. Construction shoring. Shoring, or false work, is
considered to be any temporary structure which supports
structural elements of concrete or other material during
their construction or erection. The loads due to this false
work and the supported elements must be accounted for in
the dam design.
9-2. Construction Loads
9-3. Lateral Earth Loads
a. Cofferdam tie-in loads. Cofferdam tie-in loads are
encountered on dam projects that are constructed either
within the river in phases or where additional dam structures are provided at an existing project. These loads are
caused by either cellular or embankment cofferdams constructed for a phase subsequent to the dam construction
which uses a portion of the newly completed or existing
structure as a portion of the dewatering cofferdam. Loads
not to be overlooked in the design of a cofferdam tie-in
include loads that are applied eccentrically and impart a
twisting force to the foundation, loads that cause an
unsymmetrical load to the dam pier, and concentrated
loads due to tie-in details to the dam pier. These loads
must be accounted for in the design, but they are
normally considered an unusual condition.
Lateral earth loads can be due to backfill or silt deposition. Careful investigation of available backfill materials
and methods of backfilling, as well as the potential for silt
accumulation, is of primary importance.
b. Construction equipment. Loads due to construction equipment are normally small in comparison to other
loads but should be accounted for when they are expected
to be present during construction. The loads may result
from both moving and stationary equipment.
c. Loads on partially cured concrete. Loads should
not be placed on concrete until the concrete has achieved
sufficient strength. Intermediate strength requirements
should consider proposed loads, including forming and
shoring systems, and concrete strength data.
d. Surcharge. In some instances, the design of vertical walls below grade will be affected by wheel loads or
other surcharge loads on the ground surface. These loads
should be considered in the structural stability calculations
and in the detailed design as appropriate. They should be
a. Backfill loads. The dam design should include
the forces due to dry, naturally drained, saturated, and
submerged soil conditions corresponding to the applicable
loading condition, i.e., construction operation, maintenance, and so forth. The corresponding angle of internal
friction of the proposed backfill material for the conditions expected to result from the proposed field placement
method should also be included. Generally, “at rest”
pressures should be used for gravity sections on rock and
piling foundations. Values for these pressures should be
determined for the various conditions of the backfill
(drained, saturated, or submerged) by soil analysis
methods. The lateral pressure coefficient Ko varies from
about 0.3 for loose, granular soil to perhaps 1.0 for compacted clay and fine grained material. The lateral earth
pressure coefficient should be determined through consultation with the geotechnical engineer. Factors that affect
the lateral earth pressure coefficient are wall and foundation flexibility. See EM 1110-2-2502.
b. Silt and sediment. Horizontal pressures produced
by possible silt deposits must be considered in the dam
design. Model studies can only indicate tendencies for
locations of silt accumulations. If the model studies indicate tendencies for silt build-up, conservative assumptions
should be used. Caution should be exercised in assuming
that silt and sediment will be removed, because of the
EM 1110-2-2607
31 Jul 95
possibility that removal may not continue throughout the
life of the project.
c. Vertical shear. Vertical shear, or downdrag, is the
change in the state of stress in the soil backfill as vertical
loading changes. These changes occur during initial construction (backfill is consolidating) and possibly during
dewatering (the dewatered monolith tends to move up
with respect to the stationary backfill). The procedure for
computing the vertical shear is to use a vertical shear
coefficient Kv applied to the effective vertical stress of the
soil. The vertical shear is then applied at a plane extended at the outermost extremity of the wall. A detailed
description of the procedure for gravity walls founded on
rock is included in EM 1110-2-2602.
9-4. Hydrostatic
a. Horizontal water pressure. The horizontal water
pressure against the dam is variable and depends on the
waterway stages that prevail at a particular time or on
other conditions which may produce higher pressures.
For most monoliths that are not required to resist lateral
earth pressures in conjunction with water pressures, the
maximum pressures are easily determined. Dam abutment
monoliths often have backfill adjacent to one side.
(1) No definite rule can be followed in determining
the level of the groundwater in the backfill adjacent to the
dam. The saturation level varies between upper and
lower pool elevations, depending on the physical characteristics of the backfill material. The location of the saturation line should be based on thorough laboratory tests of
the dry and wet characteristics of the soil, the extent of
compaction expected, and the effect of local climatic
(2) A majority of the navigation dams in the United
States are located in natural waterways where the backfill
material used has granular characteristics. This material
has a tendency to drain and become saturated with an
approximately straight-line variation between pool elevations. For projects with fairly stable levels, these assumptions should be sufficiently accurate to give satisfactory
results. However, varying pool levels and use of impervious backfill material will probably cause considerable
departure from straight-line variation.
(3) For dam installations with a lower pool subject to
greater fluctuations than the upper pool, a lower pool
stage exceeded no more than a small part of the time
should be selected from the stage duration curves. In this
case, the saturation line can be constructed between this
lower pool level and the normal upper pool level, and the
height of the ground water table can be determined
accordingly for that portion of the dam under consideration. The extent of saturated earth must be established
with a reasonable degree of accuracy in order to accurately represent horizontal force due to earth, water, and
uplift pressures.
(4) In addition to the usual stabilized groundwater
levels caused by normal discharges, extreme loading
conditions due to raised saturation levels must also be
investigated. These conditions include the effect of
locally heavy rains without an accompanying rise in the
pool stages and of flood discharges which cause the earth
to become saturated. Following flood discharges, the pool
levels often approach their normal levels more rapidly
than the fill material can drain. Although these increased
loads are serious and should be investigated, they are
normally of short duration and infrequent occurrence, and
the stability requirements are usually relaxed for these
increased loads. For a free-draining backfill in this condition, consider the backfill drainage as partially effective
and assume, for design purposes, the saturation line to be
halfway between its normal location and the top of the
fill. The uplift pressure adjacent to the backfill should
correspond to the assumed saturation level.
b. Uplift. Uplift due to hydrostatic pressure at the
junction between the dam and foundation must be considered. Effective downstream drainage will generally limit
the uplift at the toe of the dam to tailwater pressure. The
uplift pressure at any point under the structure will be
dependent on the presence, location, and effectiveness of
foundation drains. Any existing artesian pressures should
also be considered. Determination of uplift can be made
using the guidance in EM 1110-2-2200. Since uplift may
have a relieving effect on foundation loads, the stability of
dam monoliths should be investigated for both the maximum and minimum probable uplift pressures. Dewatering
systems used for construction can significantly reduce and
possibly eliminate uplift and should be thoroughly investigated. A free body diagram of uplift pressures acting on
the base of a dam is shown on Plate 18.
(1) Flow net and creep theory. The fundamental
design principles and guidance concerning seepage considerations are detailed in EM 1110-2-1901. Additional
theory is given in the documentation for the CSLIDE
computer program.
(2) Geotechnical investigations. The permeability of
the foundation soils greatly affects the uplift pressure;
EM 1110-2-2607
31 Jul 95
therefore, close coordination with geotechnical engineers
is needed in determining uplift pressures.
c. Vertical water. The downward force of water
above the overflow section, stilling basin, flip or roller
bucket, and apron should be considered to take the shape
of the hydraulic profile. The shape should include the
hydraulic jump of the water flowing over the section.
Variations in the shape of the hydraulic profile should be
investigated based on the loading condition being considered. Any contained water should also be included as a
force acting downward.
d. Pulsating pressures. Pulsating pressures against
sidewalls and stilling basin slabs are known to exist. The
location and magnitude of these pressures can be investigated with a hydraulic model as was done for Baldhill
Dam (Fletcher 1993).
EM 1110-2-2400 recommends
increasing the static load by 1.5 to account for pulsating
pressures. These pressures should be accounted for in the
design of stilling basin slabs and sidewalls.
9-5. Earthquake or Seismic
Two general approaches to determining seismic forces
include the seismic coefficient method and a dynamic
analysis procedure.
load.) The magnitude of the impact forces generated by a
particular collision depends on numerous factors such as
size, speed, and angle of tow; stiffness of object being
struck; and stiffness of barge. An analytical approach
which can be used to approximate the maximum impact
forces on structures located on the inland waterway system is presented in ETL 1110-2-338.
9-7. Line Loads
When check posts or line hooks are provided on dam
structures, a hawser pull of 160 kips should be used for
the design of the posts or hooks and their anchorages.
9-8. Ice and Debris
The magnitude of the ice load to be figured into the
design of dams should be estimated for the particular
structural element being designed, with consideration
given to locale and available records of ice conditions.
The effect of wedging ice flows between piers should be
considered, and the most unfavorable direction of ice load
chosen. Accepted practice has been to assume a load of
5,000 lb/ft of width of dam to account for impact of
debris and ice loads. For more detailed methods of computing ice forces, see EM 1110-2-1612.
9-9. Wave Loads
a. Seismic coefficient method. The seismic coefficient
method (also known as the pseudo-static method) of analysis should be used only as a preliminary means of determining the location of resultant and sliding stability of
monoliths, or to provide an initial pile layout. If the
seismic loads computed by the seismic coefficient method
indicate a critical load case, a more rigorous dynamic
analysis should be performed as described in Chapter 11.
The coefficients used are considered to be the same for
the foundation and are uniform for the total height of the
monolith wall. Seismic coefficients used in design are
based on the seismic zones provided in ER 1110-2-1806.
Details of these procedures are contained in
EM 1110-2-2200.
b. Dynamic analysis procedure.
Procedures for
performing a dynamic analysis are contained in
ETL 1110-2-365.
9-6. Tow Impact
Tows operating on inland waterways on occasion lose
control and collide with dam piers and appurtenant
structures. (This load is not applied concurrently with ice
Wave loads are usually more important in their effect on
gates and appurtenances, but they may in some instances
have an appreciable effect on the design of the dam structure. Wave loads are not calculated concurrently with the
ice and debris loads. Wave dimensions and forces depend
on the extent of water surface or fetch, the wind velocity
and duration, and other factors. More information relating
to waves and wave pressures is presented in CERC’s
“Shore Protection Manual” (SPM), Volume 111 (SPM
9-10. Wind Loads
Wind and subatmospheric pressures may ordinarily be
neglected in analyses for low-navigation dams. Wind
pressures on the exposed piers, service bridge, crane, etc.,
should be assumed to act in the most unfavorable direction, and also should be assumed as 30 lb/sq ft (corresponding to a wind velocity of 85 mph). The load should
be assumed to act on the following surfaces:
a. Bridge girders - One and one-half times the vertical projection of the span.
EM 1110-2-2607
31 Jul 95
b. Bridge trusses - The vertical projection of the span
plus any portion of the leeward trusses not shielded by the
floor system.
resulting from the dewatering of one gatebay while the
adjacent gatebay remains operational. The torsional shear
from this loading should be considered, and the pier
should be reinforced appropriately.
c. Crane - The vertical projection of the crane.
9-15. Sheet Pile Cutoff Loads
d. Pier - The vertical projection of the exposed parts
of the pier and accessories.
For locations where the wind velocities exceed the previously stated velocity, correspondingly higher wind load
allowances should be used. TM 5-809-1 contains additional guidance on wind loading.
9-11. Gate Loads
All reactions determined from analysis of the gates should
be accounted for in the design of the dam. These include
anchorage forces from tainter gates, wickets, hinged-crest
gates, and other gates. Internal forces from post-tensioned
tainter gate trunnion girders must also be considered in
the design of dam piers. Gate piers are subject to eccentric lateral loading, such as that resulting from the raising
of one gate while the adjacent gate remains closed. The
monolith stability and the pier design should reflect these
loading conditions. The torsional shear from this loading
should be considered, and the pier should be reinforced
9-12. Bridge Loads
The bridge should be designed for dead and live loads
including crane and bulkhead loads, as well as wind and
seismic loads. Bridge loads are imparted to the dam
structure as a result of piers that support a service, access,
pedestrian, or highway bridge. Bridge loads should be
considered in the stability computations as well as in
determining localized stresses in the dam pier.
9-13. Crane Loads
Loads due to cranes and other machinery can be significant and must be included in the analysis of the structure.
The loads may result from both moving and stationary
equipment, such as bulkhead handling equipment and
tainter gate hoists. These loads should be applied as point
loads at the appropriate locations.
9-14. Bulkhead Loads
Reactions from maintenance or emergency bulkheads
should be accounted for in the design of the dam. Gate
piers are subject to eccentric lateral loading, such as that
A sheet pile cutoff wall can impart a load to the structure
if the sheet pile wall is subject to an unbalanced loading,
as in the case where uplift pressures on each side of the
sheet pile wall vary due to a pressure relief system or
seepage losses. Past analyses showed this load to be
negligible in comparison to other loads except in the case
of sheet pile driven deep with a high section modulus. In
this case, the load should be based on an analysis similar
to that presented in EM 1110-2-2602, Chapter 8.
9-16. Monolith Joint Loads
a. Waterstop related. Pressures in monolith joints
should be evaluated based on the critical condition of
waterstops being either ruptured or intact to give the
worst case.
b. Keying between structures. Dam structures are
typically designed so each monolith acts as a separate
structural unit independent of adjacent monoliths. However, in some cases it may be beneficial to key monoliths
together. A typical case is where the upstream end of a
stilling basin is keyed to the downstream end of a dam
monolith to satisfy stability requirements for the stilling
basin. Both monoliths should be designed to withstand all
forces that may be transferred across the joint for both
stability and local considerations. A typical keyed joint is
shown in Plate 2. See paragraph 11-3f for additional
information on dowels and reinforcing between joints.
c. Reinforcing bars. Dowels or reinforcing bars can
be used to prevent differential movement between monoliths, in both the lateral and the longitudinal direction.
The reinforcing must be designed to account for the complete load transfer between monoliths, and the monoliths
designed to withstand all forces that may be transferred
across the joint for both stability and local considerations.
9-17. Superstructure Loads
Superstructure loads are imparted to the dam structure as
a result of appurtenant structures such as machinery
rooms placed upon the top of the dam piers. Loads from
these structures should be considered in the stability computations as well as in determining localized stresses in
the dam pier.
EM 1110-2-2607
31 Jul 95
9-18. Thermal Loads
residual stresses which would be additive to seismic loads.
This topic is covered in Chapter 12.
Thermal loads may be significant in determining cracking
potential for a concrete monolith and also in determining
EM 1110-2-2607
31 Jul 95
Chapter 10
Design Criteria
10-1. Applicability and Deviations
The design criteria set forth in this chapter apply in a
general sense to the design and analysis of dam structures.
Conditions that are site-specific may necessitate variations
which must be substantiated by study and testing of both
the structure and the foundation.
10-2. Load Cases
a. Usual. Dam structures are designed for usual load
conditions, those that occur most commonly during the
life of a project, including both normal operating and
frequent flood conditions. Basic allowable stresses and
safety factors apply in these cases.
b. Unusual. Higher allowable stresses and lower
safety factors may be used in accounting for unusual
loading conditions such as maintenance, infrequent floods,
barge impact, construction, hurricanes, or earthquakes
with nonspecific ground motions for OBE (operating basis
earthquake). For these conditions, allowable stresses may
be increased up to 33 percent. Lower safety factors for
pile or foundation capacity may also be used.
c. Extreme. High allowable stresses and low safety
factors are used for extreme loading conditions such as
accidental or natural disasters that have a remote probability of occurrence and that involve emergency maintenance
conditions such as earthquakes with nonsite-specific
ground motion for MCE (maximum credible earthquakes).
For these conditions, allowable stresses may be increased
up to 75 percent. Low safety factors for pile or foundation capacity may be used as described for unusual loads.
Special provisions (such as field instrumentation, frequent
or continuous field monitoring of performance, engineering studies and analyses, and constraints on operational or
rehabilitation activities) are required to prevent catastrophic structure failure during or after extreme loading
conditions. Deviations from these criteria for extreme
loading conditions should be formulated in consultation
with and approved by CECW-ED.
10-3. Earth and Rock Foundations
Generally, an earth- or rock-founded structure is the most
cost-effective foundation alternative. A prime consideration in selecting a foundation system is differential settlement. Deflection and differential settlements must be
within acceptable limits for the serviceability of the gates
and other operating equipment, and adequate stability
must be provided. Adequate stability is attained by specific limitations on the magnitude of the foundation pressure (bearing capacity) and the resistance to sliding, and
on the location of the resultant of the applied forces
within the base of the structure.
a. Foundation pressure.
(1) In general, allowable foundation pressures should
not be exceeded for any loading condition; however, the
allowable values may be different for usual and extreme
load cases. For comparison, only one allowable foundation pressure per material should be used, and an increase
of one-third should be allowed for unusual and extreme
load case categories. For bearing capacity, EM 1110-11905 allows a safety factor of 2.0; however, current practice in the Corps is to use 3.0 for usual load cases and 2.0
for unusual or extreme load cases.
(2) Base pressure computation should be made by
uniformly distributing the normal component of the resultant of all forces on the structure (including uplift) as a
reaction on the base (or plane of investigation) by means
of the general flexure formula or by equations of equilibrium. Uplift should be adjusted in areas of non-compression. Foundation pressure is equal to base pressure plus
uplift pressure. Therefore, the stability design should be
checked using full uplift forces for overturning and without uplift forces for maximum foundation pressures.
b. Sliding.
(1) Purpose. The purpose of a sliding stability analysis is to assess the safety of a structure against a potential failure due to horizontal movement. The potential for
sliding failure may be assessed by comparing the applied
shear forces to the available resisting shear forces along
an assumed failure surface. A sliding failure is imminent
when the ratio of the applied shear forces to the available
resisting shear forces is equal to one.
(2) Soil rock shear strength. The shear strength of
the soil and/or rock that comprises the foundation (failure
surface) is sensitive to the duration of the load, the soil’s
ability to drain, the saturation elevation, the number of
layers, and many other conditions. Due to these sensitivities, a fully coordinated team of structural, hydraulic,
and geotechnical engineers and geologists should be
formed to ensure that all pertinent engineering considerations are adequately integrated into the analysis and the
correct shear strengths are used.
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(3) Analysis model.
(a) The shape of the failure surface may be irregular,
depending on the homogeneity of the backfill and the
foundation material. The failure surface may be composed of any combination of plane and curved surfaces.
However, for simplicity, all failure surfaces are assumed
to be planes which form the bases of wedges, as shown in
Figure 10-1.
(b) Except for very simple cases, most sliding stability problems encountered in engineering practice are
statically indeterminate.
To reduce an indeterminate
problem to a statically determinate one, the problem must
be simplified by dividing the system into a number of
rigid body wedges. This division arbitrarily assumes the
direction of the equilibrium forces which act between the
wedges and neglects any frictional forces between adjacent wedges.
(c) The failure surface can be divided into wedges, as
shown in Figure 10-1. In this example, the base of a
wedge is formed from a section of the failure surface that
lies in a single soil material or along the base of the structure. The interface between any two adjacent wedges is
assumed to be a vertical plane which extends from the
intersection of the corners of the two adjacent wedges
upward to the top soil surface. The base of a wedge, the
vertical interface on each side of the wedge, and the top
soil surface between the vertical interfaces define the
boundaries of an individual wedge.
(d) In the sliding analysis, the dam monolith and the
surrounding soil are assumed to act as a system of
wedges, as shown in Figure 10-1. The soil-structure
system is divided into one or more driving wedges, one
structural wedge, and one or more resisting wedges.
(e) Depending on the geologic conditions of the foundation material, the location of the total failure surface or
parts of the failure surface may be predetermined.
Natural constraints at the site may also predetermine the
inclination of some of the failure planes or the starting
elevation of the failure planes adjacent to the structure.
Conditions which warrant the predetermination of parts of
the failure surface include bedding planes and cracks in a
rock foundation.
(4) Analysis procedure of the soil-structure system.
An iterative procedure can be used to find the critical
failure surface. For an assumed factor of safety (FS), the
inclination of the base of each wedge is varied to produce
a maximum driving force for a driving wedge or a
minimum resisting force for a resisting wedge. The
assumed FS is varied until a failure surface is produced
that satisfies equilibrium. The failure surface which
results from this procedure will be the one with the lowest
FS. Finite element analysis procedures may also be used.
(5) Sliding factor of safety (FS). Limit equilibrium
analysis is used to assess stability against sliding. An FS
is applied to the factors which affect the sliding stability
and are known with the least degree of certainty. These
factors are the material strength properties. An FS is
applied to the material strength properties in a manner
that places the forces acting on the structure and soil
wedges in equilibrium. Because the in-situ strength parameters of rock and soil are never known exactly, one role
of the FS is to compensate for the uncertainty that exists
in assigning single values to these important parameters.
In other words, the FS compensates for the difference
between what may be the real shear strength and the shear
strength assumed for the analysis. Sliding stability criteria for navigation dams are listed below:
• Usual
• Unusual
• Extreme
(6) Detailed design. Detailed design procedures and
multiple wedge derivations can be found in
ETL 1110-2-256.
(7) Computer programs. The computer program
CSLIDE can assist in performing a multiple wedge sliding
c. Location of resultant. The location of the resultant of all forces within the base (or limits of the plane of
investigation) determines what percentage of the base is in
compression. See Figure 10-2. If the resultant lies within
the kern (middle third), then the entire base is in compression. This requirement applies to usual load cases. If the
resultant lies outside the kern but within the base, then
only a portion of the base area is in compression. This
portion can be expressed as a percentage of the base
computed from the general flexure formula or from the
equilibrium equations. At least 75 percent of the base
should be in compression for unusual load cases. This
measurement is consistent with an eccentricity not exceeding one-fourth of the base length, and it is a suitable
approximation for all base shapes. Because the resultant
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Figure 10-1. Wedge analysis model
Figure 10-2. Location of resultant
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is required to fall within the base only for extreme load
cases, the corresponding percentage of the base in compression will be “greater than zero.”
These specific
requirements are true only for structures of unit width or
with rectangular bases and subject to bending about one
principal axis; however, these concepts are extended to
three-dimensional (3-D) structures with irregular bases
and subjected to biaxial bending loads.
stresses normal to the plane to the compressive range
only. For unusual load cases, 75 percent of the base
should be in compression when the normal stress component does not exceed the permissible tensile stress for the
material (e.g., maximum fiber stress in plain concrete due
to factored loads and moments shall not exceed a tensile
stress of 0.05f’c ).
10-5. Uplift and Flotation
d. Settlement. Foundation pressures should not produce total differential settlements that result in operational
difficulties (e.g., improper operation of gates and rupture
of water stops). In locations where detrimental settlement
of dam foundations might occur, a settlement analysis
should be made as presented in EM 1110-1-1904. If the
settlement analysis indicates a possible concern, the settlement should be corrected by extending the foundation to
reduce base pressures, designing alternative foundation
(piles), using an alternative site, or using means to ensure
that monoliths move together as discussed in Chapter 9.
10-4. Internal Stability
For gravity sections, structural adequacy within the body
of a section is attained by limiting internal stresses to
values which do not exceed the safe working stresses of
the material under stress. Internal instability will be a
result of overturning forces and excess pore pressure.
Pore pressures may be estimated by methods presented in
EM 1110-2-2602. In general, horizontal planes above the
foundation are required to have the resultant force inside
the kern. For usual load cases, this requirement limits
These items are closely related in meaning, and both
usually act to minimize the degree of structural stability
with respect to sliding and overturning. Uplift is determined from seepage analysis by methods presented in
Chapter 9. The stability analysis with regard to flotation
should be done in accordance with EM 1110-2-2602.
10-6. Pile Criteria
If deflection and differential settlements are not within
acceptable limits for the serviceability of the gates and
other operating equipment, and adequate stability cannot
be attained, a pile foundation should be considered. The
pile cap (dam structure) should be modeled as either a
rigid block or a flexible base consistent with flexural
properties of the pile cap. The pile response is usually
based on linear elastic behavior with limiting axial and
lateral deflections of 1/4 and 1/2 in., respectively. In
general, the FS for axial pile capacity varies between
1.15 and 3, depending on the method of predicting the
capacity and the loading condition. Detailed guidance on
pile foundation design is provided in EM 1110-2-2906.
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Chapter 11
Analysis and Design
11-1. General
This chapter addresses the criteria, procedures, and parameters necessary for the analysis and design of the foundation system and the dam structure. Design of the project
involves in-depth study of soil/structure interaction, stability analysis, and structural analysis.
11-2. Structural Analysis
a. General. A dam typically consists of a series of
3-D concrete structures (monoliths) surrounded by
soil/silt, rock, and water. These structures are founded on
either rock, soil, or piles and are subjected to a variety of
external and internal soil and water loads.
b. Two-dimensional (2-D) analysis. An analysis of a
2-D slice through a monolith can reliably indicate the
behavior of the monolith under the following conditions:
(1) When the cross-section geometry of the structure,
the soil and water conditions, the support conditions, and
the other loading effects are constant throughout an
extended length of the monolith.
(2) When a 2-D slice, obtained by passing parallel
planes perpendicular to the longitudinal axis of the monolith, typifies adjacent slices and is sufficiently remote
from any discontinuities in geometry and loading (i.e., the
slice is in a state of plane strain).
c. Two-dimensional (2-D) frame analysis. Structural
analysis of the dam component is based on the assumption that the various slabs, walls, etc., of the structure
interact as elements (members) of a 2-D plane frame.
Establishment of a plane frame representation of the structure requires designation of parts of the structure as flexible members connected at their ends to joints. While
some regions of the structure may lend themselves to
treatment as flexible members (i.e., beam bending elements), there are significant zones of mass concrete that
cannot be assigned bending characteristics. For analysis
purposes, these zones are assumed to be rigid. The location and extent of these rigid zones will depend on the
type of monolith being analyzed. The size of these zones
must be determined to obtain reliable indications of the
behavior of the 3-D monolith using a frame model. The
frame should be calibrated by determining rigid zone sizes
to agree with the stress results from a finite element
analysis using plane strain elements for a section with
similar geometry.
d. Three-dimensional (3-D) analysis. If the dam
monolith geometry and/or loading does not meet the
above requirements for a 2-D frame analysis, a 3-D finite
element computer model should be used to analyze the
monolith. Guidance on modeling of structure for linear
elastic finite element analysis is provided in other Corps
e. Seismic.
Earthquake-induced ground motion
effects must be considered in the analysis and design of
navigation dam structures.
The structures must be
designed for the inertial forces from the structure mass
combined with hydrodynamic pressures. These forces
should be combined with any dynamic soil pressures
generated within the backfill. Linearly elastic procedures
used in design include the response spectrum analysis and
the time history analysis.
(1) Seismic coefficient method. Traditional design
practice based on the seismic coefficient method failed to
account for the dynamic response characteristics of the
soil-structure-water system. Dams designed by the seismic coefficient methods may not be adequately proportioned or reinforced to resist forces generated during a
major earthquake. Therefore, this approach should be
used only as a simple, preliminary means of checking a
new design or an existing structure for seismic susceptibility. It should not be used as a final analysis procedure
for controlling member proportions or for remedial design
(with the exception of those cases where extensive results
or comparisons of previously designed or evaluated structures are available).
(2) Response spectrum analysis. A response spectrum is a plot of the maximum response of a series of
single-degree-of-freedom (SDOF) systems with varying
periods or frequencies. A response spectrum analysis can
provide an analysis procedure that partially accounts for
the dynamic structural properties of the system. The
response spectrum analysis can be accomplished by either
a finite element procedure or a frame analysis. Results
from these procedures provide only the absolute maximum stresses and forces due to the methods of combining
modal responses.
(3) Time history analysis. The exact time history of
a response quantity can be produced using this technique;
therefore, an exact sign-dependent stress distribution can
be found at any given time. However, a digitized design
earthquake record for the site is needed, and a significant
EM 1110-2-2607
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computing effort is required for the numerical integration
of the differential equation of motion using small time
Another good reference for the calculation of bearing
capacities is the program documentation for the CASE
computer program CBEAR.
(4) Guidance. A detailed description of the response
spectrum and the time history analysis is provided in
ETL 1110-2-365.
d. Earth pressures settlement. For a gravity structure, settlement analyses can be performed by following
the principles set forth in EM 1110-1-1904.
f. Nonlinear incremental structural analysis (NISA).
A NISA should be conducted on massive concrete structures if it will help achieve cost savings, develop more
reliable designs for structures that have exhibited unsatisfactory behavior in the past, or predict behavior in structures for which a precedent has not been set. A NISA
first requires that a time-dependent heat transfer analysis
be performed. Further discussion on NISA is included in
Chapter 12.
11-3. Foundation Design and Soil/Structure
a. Type of foundation. Another critical aspect in the
design of navigation dams involves determining the
appropriate foundation type. The foundation conditions
often influence the site selection for a navigation lock
project. The foundation characteristics should therefore
be determined for each tentative site at an early stage of
the investigation. These characteristics are usually determined by using available data and a minimum of foundation exploration. Sites chosen for further investigation
should have foundation characteristics that would allow
the dam structures to be constructed at a reasonable cost.
The possible sites selected for study from a review of
topography and hydraulics can thus be reduced to one or
two after reviewing the site from a foundation and navigation standpoint. Final site selection requires extensive
foundation exploration of the remaining sites under consideration. Before a pile foundation is selected, the foundation characteristics must be well-defined and a
sufficient analysis of them must be made.
b. Foundation pressures (compatible deformations).
Foundation pressures depend on the type of foundation
material, the nature of the loading, and the size and shape
of the monolith. For gravity-type monoliths (due to their
rigidity), a linear distribution of base pressure can be
assumed. However, for structural monoliths with a flexible base, the distribution of base pressure should be based
on a soil/structure interaction analysis.
c. Bearing strength of soils. The bearing strength of
soils and methods for its determination based on field and
laboratory test data are described in EM 1110-1-1905.
e. Pile foundations.
(1) Determination of type of foundation--soil or pile.
(a) Determining the foundation type is probably the
most critical aspect in the design of a dam. Because this
decision will affect the project cost, the foundation type
should be determined at the feasibility report stage of the
project. This analysis should involve the use of a
thorough subsurface investigation and testing program to
define the soil strengths and parameters. For major structures an in-situ pile load test will normally be required.
(b) The criteria for selecting a soil or pile foundation
are based on economic considerations and site-specific
characteristics. Usually, a soil foundation is more economical if special measures (deeper excavation, elaborate
pressure relief system, etc.) are not required. In addition,
the structure on a soil foundation must satisfy stability
requirements for sliding and overturning, as well as resisting uplift (flotation) and earthquake forces. At some
sites, liquefaction of the foundation in the event of an
earthquake becomes a determining factor in selecting the
foundation type. Differential settlements between monoliths should also be considered in determining whether a
soil or pile foundation will be used. If expensive special
measures are required to make a soil foundation suitable
for use, then a pile foundation should be studied and its
cost compared to the cost of a soil foundation. The piling
selection process should consider all reasonable types of
piling, the site’s geotechnical conditions, availability of
material, construction limitations, and economics. The
estimated quantities of piling can be based on minimum
spacing and approximate lateral and vertical capacities for
one or two typical monoliths. The most cost-effective
type of pile foundation that satisfies engineering requirements is thus determined for comparison to the soil foundation. Computer programs such as CPGA (rigid base) or
CWFRAME (flexible base) or other finite-element programs are useful for designing pile foundations. The final
decision between a soil and a pile foundation is then
based on a cost comparison using these refined pile
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(2) Design guidance. Detailed design guidance for
pile foundations is contained in EM 1110-2-2906.
f. Design considerations. Dowels or reinforcing bars
can be used to prevent differential movement between
monoliths. These may be bonded, bonded on one side, or
greased on each side of the joint, and they may be posttensioned. The reinforcing should be detailed to facilitate
construction and so that it is not exposed to water in the
joint. See paragraph 9-16b for a discussion of joint loads.
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Chapter 12
Concrete Design
12-1. General
Most navigation dams are constructed as massive concrete
structures (defined by American Concrete Institute Committee 207 as “any large volume of cast-in-place concrete
with dimensions large enough to require that measures be
taken to cope with the generation of heat and attendant
volume changes to minimize cracking”).
EM 1110-2-2000 for a complete discussion of standard
practice for concrete construction. There are three types
of massive concrete structures commonly used for civil
works projects: gravity structures, thick shell structures,
and thick reinforced plates. Selection of concrete which
meets design requirements is critical to long-term performance of these structures. The design requirements
generally include the following characteristics:
a. Strength. Strength is an important characteristic of
concrete. Typically, 3000-psi- or 4000-psi-strength concrete is utilized, but lower interior strengths or higher
strengths may be used as well. Concrete strength may be
varied by zones and may not always be limited to the
normal 28-day designation. A 90- or 120-day strength,
which is characteristic of concrete with a high percentage
of pozzolan substitution for cement, may be utilized for
long-term construction projects.
b. Durability. Concrete must resist deterioration by
the environment to which it is exposed, including freezing
and thawing, wetting and drying, chemicals, and abrasion.
c. Placeability. Placeability is described by the terms
workability and consistency. These are affected by many
factors, including water content, cement or pozzolan, and
maximum size aggregate--the last of which, in turn, is
influenced by the presence of steel reinforcement or
embedded items.
d. Economy.
The maximum economy can be
achieved by minimizing the amount of cement utilized
and, where appropriate, replacing portland cement with
generally less expensive pozzolans. Economy is also
improved by using the maximum size aggregate consistent
with the dimensional requirements of the structures on the
project, and by using aggregates available to the project.
e. Ductility. In areas of high seismic ground motions,
the tensile strain capacity may be of great importance.
12-2. Nonlinear Incremental Structural Analyses
Determining the appropriate measures to cope with the
problems associated with a massive concrete structure,
including the division of the structure into separate elements such as piers, sills, or monoliths, is an important
task. For major structures, a NISA should be used as a
design for massive concrete structures if it will help
achieve cost savings, develop more reliable designs for
structures that have exhibited unsatisfactory behavior in
the past, or predict behavior in structures for which a
precedent has not been set. A NISA requires that a timedependent heat transfer analysis be performed. The
results of the heat transfer analysis are then used in a
time-dependent stress analysis that simulates the incremental construction of the structure and uses nonlinear
properties for modulus of elasticity, creep, and shrinkage.
For more information on performing a NISA, refer to
ETL 1110-2-324.
12-3. Parameters Affecting Cracking in Concrete
a. General. Cracking in non-massive reinforced
concrete structures is primarily the result of tensile strains
produced by loads applied to the structure. Steel reinforcement is provided to carry the tensile stresses. Cracking in mass concrete is primarily caused by restraint of
volume change due to heat generation and subsequent
cooling, autogenous shrinkage, creep/stress relaxation, or
other mechanisms. Restraint limits the respective changes
in dimensions and causes corresponding tensile, compressive, torsional, or flexural strains in the concrete. Of
primary concern in mass concrete structures is restraint
which causes tensile stresses and corresponding tensile
strains. Restraint may be either external or internal.
External restraint is caused by bond or frictional forces
between the concrete and the foundation or underlying
and adjacent lifts. The degree of external restraint
depends on the relative stiffness and strength of the newly
placed concrete and the restraining material and on the
geometry of the section. Abrupt dimensional changes or
openings in a monolith, such as wall offsets, gallery
entrances and offsets, and reentrant corners, have caused
external restraint that has resulted in cracking in concrete
structures. Internal restraint is caused by temperature
gradients within the concrete. The warmer concrete in the
interior of the mass provides restraint as the concrete in
the periphery of the mass cools at a different rate due to
heat transfer to its surroundings. The degree of internal
restraint depends upon the total quantity of heat generated,
the severity of the thermal gradient, the thermal properties
of the concrete, and thermal boundary conditions.
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b. Geometry. The geometry of the structure is of
course a major contributing factor to the behavior of the
structure. Therefore, a NISA should not be performed
until the structural geometry is at a stage where only
minor changes to it are expected. While this parameter
may be more difficult to alter than others, there may be
instances in which a change is necessary. If such a
change is made to the geometry of the structure, then
coordination between all disciplines is necessary to ensure
the change does not have an adverse effect on some other
function of the structure. A change in the geometry will
generally require some type of revision to the model’s
c. Reinforcing. Reinforcing is an integral part of nonmassive concrete structures and of many of the massive
concrete structures used within the Corps of Engineers.
Reinforcement for all non-massive concrete structures
should be designed in accordance with EM 1110-2-2104.
See EM 1110-2-2000 for a comprehensive discussion of
standard practice for concrete construction. For large wall
and floor sections, reinforcement spacing should generally
be set at 12 in. for ease of construction. In non-massive
concrete sections, temperature and shrinkage reinforcement is required to control cracking. Generally, small
bars at close spacing provide the best control. However,
for walls 2 ft thick or more, number 9 bars at 12-in.
spacings are commonly used to ease construction while
still providing the required steel percentage. In gravity
walls, however, the requirements of EM 1110-2-2104
regarding the minimum steel do not apply. To date there
has been limited use or recognition of reinforcing in
NISA analyses, due to the fact that many of the structures
analyzed had no cracking problems, and adding reinforcing in the model when cracking is not occurring has little
effect on results. If an analysis predicts cracking in a
structure and measures to eliminate the cracking are
unsuccessful, then reinforcement should be included in the
model. Resulting stresses in the reinforcing bars should
be monitored, reported, and compared to the yield
strength of the reinforcing. If cracking is occurring in a
location of minimal reinforcing or at corners of openings,
increasing the amount of steel transverse to the crack can
help control or arrest the crack. Typically, reinforcing
steel placed at 45 deg at corners is very effective at
arresting corner cracking. Special attention must be paid
to providing proper concrete cover for all reinforcing bars
(see EM 1110-2-2104).
d. Seismic. Reinforcing steel must be properly contained to ensure good performance during an earthquake.
See ETL 1110-2-365 for further guidance.
e. Material parameters.
(1) A number of material parameters can be controlled to limit cracking related to restrained volume
change. They include heat generation of the concrete;
mechanical properties of the concrete, including compressive and tensile strength, tensile strain capacity, modulus
of elasticity, linear coefficient of thermal expansion,
creep/stress relaxation, and autogenous shrinkage; and
thermal properties of the concrete, including specific heat
and thermal conductivity.
(2) These properties are governed by the selection of
materials used to make the concrete, including cementitious materials (portland cement, ground granulated iron,
blast furnace slag, and pozzolans such as fly ash), aggregates, chemical admixtures, etc.; and by the proportions of
these materials in the concrete mixture. Many of these
properties are also dependent on the maturity of the concrete and are thus time and temperature dependent. Close
scrutiny of the selection of concrete mixture materials and
proportions should be part of a properly conducted concrete materials study. Due consideration should be given
to the performance and economy of the selected mixture.
The study should be conducted according to the guidance
in EM 1110-2-2000 and documented in a concrete materials design memorandum.
f. Construction procedures. A number of construction parameters can be controlled to limit cracking due to
restrained volume change. They include lift height, time
between placement of lifts, concrete placement temperature, curing method, use of insulation, monolith geometry
including section thickness, monolith length, and location
and size of inclusions such as galleries. In addition, the
time of year a monolith is constructed can be controlled if
it has been determined by the NISA that a particular start
date is beneficial. Any construction requirements or
restrictions identified by the NISA must be clearly stated
in the construction contract documents.
g. Vertical construction joints within a monolith.
There may be some projects for which vertical construction joints become necessary due to excessively large
concrete placements. If this is the case, lift sequences
creating vertical joints should be accounted for in the
incremental construction analysis procedure.
across a vertical construction joint should be examined
closely for determination of any special measures needed
in the design and construction of the joint (e.g., placement
of reinforcement bars across the joint face). In addition, a
3-D analysis should be considered for monoliths with
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vertical construction joints to confirm results obtained in
the 2-D analysis, because the joints themselves will be
located in the out-of-plane direction.
recommendations outlined in EM 1110-2-2000. Special
attention must also be given to providing proper concrete
cover over steel reinforcement (see EM 1110-2-2104).
12-4. Concrete Quality for Dam Spillway and
Stilling Basin
12-5. Second Placement Concrete
a. Spillway function and composition. The primary
function of a navigation dam concrete spillway is to provide a controlled release of surplus water from the
impounded pool so that the water level can be regulated
for navigation traffic use. The spillway may be composed
of the following features: ogee spillway crest and shape,
stilling basins, apron, bucket, end sill, and baffle blocks,
as well as spray walls, separation walls, and training
b. Concrete durability. The concrete for all the above
features must be able to resist the effects of environmental
deterioration, including freezing and thawing, wetting and
drying, chemicals, and abrasion. In addition, the concrete
should be able to resist damage caused by waterborne
rocks and gravel, floating ice, floating tree trunks, and
debris of all kinds in the high-velocity flowing water.
Damage to the concrete in spillways and stilling basins is
a constant maintenance problem on many existing Corps
projects. On various projects, abrasion-erosion has ranged
from a few inches to several feet, and, in some cases,
severe damage has occurred after only a few years of
operation. The fact that many spillways cannot be easily
or economically unwatered for inspection and repair
makes the initial quality and the placement of the concrete
all the more important. To protect the spillway concrete
from all the potentially damaging elements, durable
concrete mixes and proper concrete placement requirements should be provided in accordance with all the
a. Purpose. Second placement concrete is necessary
for a dam structure at locations where precise settings are
required for alignment and/or elevations for embedded
steel items. These items and locations may include horizontal seal plates on spillway crests for spillway gates,
vertical side sealing and rubbing plates for “J” seals
attached to spillway gates, machinery bases for support of
gate operating machinery, horizontal seal plates for spillway bulkheads, vertical plates for vertical-lift gates and
spillway bulkheads to bear on and roll on, corner protection for spillway bulkhead slots (upstream and downstream), dogging devices for spillway bulkheads, and
crane rails for a movable crane located on the service
b. Design consideration. These second placement
blockouts require careful sizing and detailing so that
enough space is available for adjusting the steel items to
line and grade and to allow for placing and vibrating
concrete. The following items also require special attention: the concrete mix (which must be designed with the
proper aggregate size to allow good placement); the concrete mix design (which must provide for minimum
shrinkage); reinforcing steel extending from the mass
concrete placement; additional steel for the second placement; and embedded bolts and adjustment provisions for
securing the steel items in position. For typical second
placement details, see Plate 19. EM 1110-2-2000 contains guidance in proportioning and constructing blackout
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Chapter 13
Design of Other Items
13-1. Galleries
A system of galleries, adits, chambers, and shafts is
usually provided within the body of the concrete dam to
furnish access and space for foundation drilling and grouting and for the installation, operation, and maintenance of
equipment accessories and utilities in the dam. The
primary considerations in arranging the required openings
within the dam are personnel safety, functional usefulness
and efficiency, and location of the openings with respect
to maintaining the structural integrity of the structure.
a. Ventilation. In accordance with EM 385-1-1, all of
the above-mentioned galleries and other associated features should be provided with adequate ventilation for
safe operation, maintenance, and inspection. Adits should
be equipped with doors of structural steel grillages that
allow free circulation of air in and out of the galleries.
This arrangement may be supplemented by using vent
holes in the galleries and at other selected locations and
by placing powered exhaust fans in special areas. Hydrogen sulfide gas in the galleries is a hazard to personnel.
Ventilation equipment where this gas occurs must be
b. Required dimensions. A gallery for the grouting of
the foundation cutoff will extend the full length of the
dam. It will also serve as a collection main for the seepage from the foundation drainage holes. See Figure 7-1.
The location of the gallery should be near the upstream
face of the dam and as near to the rock surface as structural design and layout will allow. It has been standard
practice to provide grouting galleries 5 ft wide by 7 ft
high. Experience indicates that increasing these dimensions can facilitate drilling and grouting operations.
Where practicable, the width may be increased to 6 ft and
the height to 8 ft. The floor of the gallery should slope
about 1/4 in. per foot to a minimum-size 12-in. by 12-in.
gutter along the upstream side. The depth of the gutter
will vary so that the bottom slopes for proper water flow
to the collection sump. The gallery is usually arranged as
a series of horizontal runs and stair flights as dictated by
the varying foundation levels. The stairs should be
provided with safety treads or a nonslip aggregate finish.
Where it is probable that equipment will be skidded up or
down the steps, metal treads are preferable since they
provide protection against damage to the concrete. Where
practicable, the width of tread and height of riser should
be uniform throughout all flights of stairs and should
never change in any one flight. Details of drilling and
grouting operations and equipment are covered in
EM 1110-2-3506.
13-2. Machinery Platforms
a. Reinforced concrete. A reinforced concrete platform is readily adaptable for tainter gate hoist machinery
support--especially for cases where the weight of the
machinery and components plus the tainter gate and lifting cables creates a very heavy loading on the platform.
The heavily reinforced concrete support members are
cantilevered off the top of the pier. If a service bridge or
walkway bridge is provided, the machinery base level and
the bridge level will be at approximately the same elevation. A heavy structural steel frame, anchored to the
concrete with embedded anchor and adjusting bolts, provides support for the machinery and components. Typically, a minimum of 1-in. cement grout is placed under
the steel frame after it is adjusted to the proper location
and elevation. The machinery and components are then
bolted to the top of the frame. See Plate 20 for layout of
a typical structural steel frame for the hoist machine and
components it supports.
b. Steel grillage with concrete deck or grating. On
smaller navigation dams where loads are not so large, a
cantilevered structural steel support assembly may be
more adaptable for use than a reinforced concrete support.
The structural steel assembly is anchored to the top of the
pier with embedded anchor and adjusting bolts. After the
support is installed to line and grade using second-pour
concrete, the machinery and components are bolted to the
top of the support assembly. The openings in the support
assembly are sometimes covered with steel grating so that
personnel will have access to all components of the hoist
machinery for maintenance, inspection, and repair
c. Design loadings. In addition to its own dead
weight and the weight of the hoist machinery and components, the cantilevered platform must be designed for the
following loads: dead weight of the tainter gate, side seal
friction, dead weight of wire ropes or chains, trunnion
friction, silt and drift accumulation on gate, ice accumulation, impact, and stall torque of electric motor. See
EM 1110-2-2702 for further information and guidance on
hoist loadings.
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13-3. Machinery Houses
a. Requirements and optional usage. In locations
where climates are severe and the seasonal icing, rain,
wind, and cold temperatures may interfere with and be a
hindrance to operational and maintenance activities, the
spillway gate operating machinery should be placed inside
an enclosure. The use of a house with enough room to
access all parts of the machinery is usually advisable.
The house may be constructed of metal (steel or aluminum) or reinforced concrete. The reinforced concrete
houses require less maintenance and can be designed to
be more aesthetically pleasing than the metal houses.
Adequate ventilation and electrical illumination will need
to be provided. In warmer climates, the spillway gate
machinery may either be enclosed by a metal cover or be
left in the open air with no cover except for parts susceptible to weather damage. These parts can be covered by
shrouds. The designer, in conjunction with operations
personnel, will need to decide which of the above options
is most desirable for a specific project. However, it is
usually a good idea to have similar machinery treatment
for all dam projects on the same waterway. A typical
concrete machinery house is shown in Plate 20.
b. Design loading. When machinery houses are made
of either metal or reinforced concrete, the design live
loading due to wind, snow, and ice must be considered
for the area where the project is located. The roof should
be designed to withstand a live load of at least 30 psf
over the entire roof area, plus the maximum live load
expected on any overhead lifting hooks or traveling hoists
attached to the roof ceiling. The thickness of the roof and
walls of a reinforced concrete structure will usually be in
the range of 6 to 8 in.
handling, equipment covers should be made of metal
13-4. Line Hooks
Line hooks should be placed upstream and downstream at
appropriate locations in the dam pier faces and adjacent
lock wall faces for use in tying up the floating plant for
maintenance and emergency activities. They are usually
placed in a series, one directly above the other, about five
feet apart starting a short distance above pool level. The
line hooks are typically fabricated from 8-5/8-in. OD,
1-in.-thick wall steel tubing (ASTM A519, Grade 4130,
condition SR) and filled with grout. Cast-iron or caststeel hooks should not be used because it is becoming
increasingly difficult to get quality castings. The line
hook and anchorage should be designed for reactions
resulting from a 160-kip line pull using normal allowable
stresses. The arrangement should include a curved steel
frame and anchorage reinforcement. See Figure 13-1 for
line hooks details.
13-5. Check Posts
Check posts, suitable for use by the floating plant in tying
up to the structures during maintenance and emergency
activities, should be provided on the top surfaces of all
piers both upstream and downstream. The check posts
are typically fabricated from 8-5/8-in. OD, 1-in.-thick wall
steel tubing, ASTM A519, Grade 4130, condition SR, and
filled with grout. Cast iron or cast steel should not be
used. Checks posts with embedment should be designed
for a minimum line pull of 160 kips using normal allowable stresses. See Figure 13-2 for check post details.
13-6. Deadman Anchorage for Floating Plant
c. Requirements for machinery. For removal and
maintenance access, all machinery houses must have
removable panels with lifting attachments that can be
handled by crane. Thus, the crane can lift off the removable panel and then lift out the heavy machinery, or any
of its components, for extensive maintenance or repair.
Where machinery covers are used in lieu of houses, lifting
attachments will be necessary on the covers, so that a
crane can lift off the entire cover should extensive maintenance or repair be necessary. Hinged panel openings
should be provided on the equipment covers for normal
inspection and maintenance activities.
For ease of
In case of uncontrolled flow through a spillway bay,
because of blockage of the bay by a barge or other vessel
or due to a machinery failure or gate malfunction, it is
advisable to furnish a means for anchoring the floating
plant above the dam. This can be accomplished by providing deadman anchorages on the banks above the dam
and locating a check post(s) on the riverward side of the
adjacent upper guide wall of the lock. The floating plant
can then tie to these items and be reasonably stable for
work in the flowing water to either place spillway bulkheads or remove the obstruction from the bay.
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Figure 13-1. Line hook recess detail
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Figure 13-2. Check post detail
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13-7. Ladders and Stairs
13-10. Handrail and Guardrail
To provide safe and timely access for normal maintenance
of and emergency attention to operating machinery and
other important parts of the dam, permanent ladders or
stairways should be provided in accordance with EM 3851-1. Permanent ladders should be used only when the use
of stairways is not practical or feasible. Stairs may be
either concrete cast in place, precast concrete, or structural
steel. Treads shall be provided with nonslip material at
least at the nosing. Ramps, rather than stairs, may be
provided when fewer than three risers are involved; the
surfaces of such ramps should be covered with an abrasive material.
Permanently fixed handrails and guardrails should be
provided, in accordance with EM 385-1-1, at all locations
on a dam structure where safety and operational needs
dictate their necessity, including the top deck of service
bridges; the tops of concrete trunnion girders; stairways,
inside or on sides of piers; walkway surfaces on piers,
especially at the tops of bulkhead slots; and around vertical access shafts and ladder recesses and the arms of large
tainter gates. Galvanized steel, aluminum, or painted steel
handrails and guardrails may be selected for use. Anodized aluminum rails and posts will require a larger pipe
diameter than steel, to meet strength criteria. Also, the
strength reduction effects of welding must be considered
in computing the required size of aluminum rails and
13-8. Access to Trunnion Area and Bulkhead
Where practical, safe ladder or stair access should be
provided to the top of all concrete trunnion girders
whereby the tainter gate trunnion pin, yoke, and arms can
be inspected and serviced. Piers will usually be wide
enough to accommodate an interior stairway from the
service bridge level down to a walkway opening on the
downstream face of the pier for access to the top of the
trunnion girder. Access to the lower part of the trunnion
girder and prestressed anchorage covers will usually
require a permanent ladder installation. Since the tops of
the upstream bulkhead slots and bulkhead dogging devices
are provided with a level walking surface, they can be
accessed from this same interior stairway and another
walkway opening. Access to the top of the downstream
bulkhead recess may be possible only from the floating
plant. However, permanently fixed ladders may be provided if practical.
13-11. Parapet Walls
Where conditions on a dam are such that concrete parapet
walls are more desirable than handrails and guardrails,
reinforced concrete parapet walls may be used as shown
in Figure 13-3. The height of the wall should be the
same as that of the metal rail, and the concrete thickness
should be at least 8 to 12 in., with proper top slopes and
possible aesthetic treatment.
13-12. Grating
Recesses, access shafts, catwalks, machinery platforms,
and pits in the dam piers and at other locations in the dam
should be provided with covers. Usually, galvanized steel
grating is provided if grating is to be manually removed.
In some cases, it may be necessary to cover the grating
with steel plate for safety purposes.
13-9. Corner Protection
13-13. Service Bridges
All bulkhead slots should be provided with structural steel
corner protection on vertical upstream and downstream
surfaces plus steel protection at the top of the slots. This
will prevent damage to the slots due to bulkhead installation activities and from flowing water and the material
that it carries. If vertical-lift spillway gates are used, the
necessary recesses in the piers will also require similar
corner protection. Corner protection may also be required
at other locations depending on whether or not they are
involved with maintenance or operational activities, subject to flowing water, or other potentially damaging
a. General. Service bridges provide support for
overhead cranes and/or provide access to mechanical
equipment located on the dam structure. Typically, traveling hoist cars or gantry cranes transport emergency
bulkheads or vertical-lift gates to each gate bay and in
some cases the navigation lock. The crane may also have
an auxiliary crane attached for use in maintenance operations. A typical hoist car with auxiliary crane, supported
by a service bridge, is shown in Plate 9. Plate 13 shows
a cross section of a spillway service bridge for the gantry
crane at John Day Dam on the Columbia River. A
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smaller service bridge which serves as a personnel walkway is shown in Plates 1 and 2. Plate 11 shows a vehicle
access bridge across the dam spillways at Lock and
Dam “D” on the Tennessee-Tombigbee Waterway.
b. Service bridge superstructure.
(1) For some of the larger dam projects on the Ohio
and Mississippi Rivers, the service bridge usually consists
of a concrete deck and up to three simply supported
American Association of State Highway and Transportation Officials (AASHTO)- type precast, prestressed girders (beneath each crane rail) that act as a composite
system. The crane rail is centered on the middle girder.
The clear opening between the upstream and downstream
girder assemblies allows passage of the crane cab and
transport of the bulkheads between the girders when the
service bridge also serves the lock chamber. The bottom
elevation of the girders is selected to allow a specified
clearance above maximum operating upper pool for navigation through the lock. This specified clearance will
usually be available from the U.S. Coast Guard and is the
same clearance as is required for the low steel of railway
and highway bridges which cross the waterway.
(2) Plate 5 shows a plan view of a service bridge that
serves both the dam spillways and the lock chambers at
the Melvin Price project on the Mississippi River. Plate 6
shows a cross section of this same service bridge. Plate 8
shows a cross section of a similar service bridge installation at Smithland Locks and Dam on the Ohio River.
c. Service bridge substructure. The service bridge
substructure is provided by the dam piers and piers
located on the navigation lock walls. Reinforced elastomeric bearing pads or rocker-type assemblies are recommended for bridge bearings. Cable restraints and concrete
shear blocks should be provided to enable positive means
of anchoring the superstructure to the substructure for
seismic loads.
d. Crane rails. The service bridge crane rails should
be sized to fit the crane wheel flanges. The 175#-peryard American Railway Engineering Association (AREA)
rail has been found suitable for projects having heavy
hoist cars that travel with heavy sectional bulkheads and
lower several sections latched together onto the spillway
sill. The base of the rail should rest on heavy bearing
plates at the service bridge deck level with embedded
anchor bolts and levelling nuts for setting the crane rail to
the proper elevation. A continuous plate may be required
to reduce concrete bearing stresses to an acceptable level.
These anchor bolts should extend through this plate and
through rail clips which anchor the rail in place. Careful
attention should be given to sizing, detailing, and locating
the expansion and contraction joints in the rail, and to
corrosion mitigation of embedded anchor bolts. Standard
AREA splice bars should be used at all rail splice locations. Bituminous material can be used to cover the rail
splice bars and the protruding anchor bolt heads and clips.
Care must be taken to ensure against water being trapped
and corroding plate anchor bolts. Details of the rail
splices and rail anchorage assembly without bituminous
coverings are shown in Figure 13-4.
13-14. Structural Instrumentation
Instrumentation for securing structural data in a dam
structure may yield the following information: uplift pressures, concrete monolith tilt or differential movement,
steel sheet pile cell interlock tension or cell movement,
anchorage tendon or rod tension stress retention, concrete
crack width increase, pore pressure, interior concrete
temperature, leakage, and alignment monumentation
observations. EM 1110-2-4300 provides adequate coverage and guidance for most of the required structural
13-15. Warning Signs
Signs reading “Danger-Stay-Away,” or “DANGER-STAY
_____ FEET-AWAY-FROM-DAM,” or some other
appropriate message should be mounted on the upstream
and downstream handrail (or parapet) of the dam service
bridge in the middle of the spillway and facing toward the
upper and lower pools. Both the frame for the signs and
the background for the letters should be of steel material
designed to withstand a minimum of 30-lb/sq-ft wind
pressure. The lettering should be a red color with a contrasting background and the individual letters should be
24 in. high or more and approximately 12 in. wide so that
the sign can be read by a person with normal vision from
a safe distance suitable for the specific project conditions.
The signs should have adequate lighting so they can be
easily read at night from this same distance. Refer to
ER 1130-2-306.
13-16. Embedded Metals
a. General. Certain navigation dam steel structures
will require embedded metals that should be installed in
second-pour blockouts. Use of the second placement
procedure allows for proper positioning of the embedded
item at the designated grade and alignment for proper
functioning of the companion structure. See Plate 19 for
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Figure 13-3. Concrete parapet detail
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Figure 13-4. Rail anchorage assembly
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typical embedded structural steel members with anchorages and adjustment bolts.
b. Embedded items and function.
The primary
embedded structural steel items and their usage are as
(1) A curved side seal and rubbing plate are used
with rubber “J” seal mounted on each side of spillway
tainter gate.
(2) A continuous sill beam serves as level seating and
metal-to-metal sealing surface for spillway gates--tainter,
vertical-lift, or roller--and spillway bulkheads.
and/or positioning purposes can be made of ASTM A-36
steel and painted, whether exposed or submerged. The
embedded portions of steel items are never painted.
However, the embedded portions need thorough cleaning
to remove mill scale, rust, and dirt prior to concrete placement. This will help to ensure a good bond of the steel
and concrete. Aluminum must not be embedded in concrete without some sort of separation coating, such as
bitumastic, on the embedded portion. Embedded items
with surfaces that serve as rubbing surfaces, guide surfaces, seal surfaces, or bearing surfaces, whether exposed
or submerged, must be made of either solid stainless steel
or clad stainless steel.
13-17. Mechanical and Electrical Features
(3) Individual sill bearing plates serve as level seating
surfaces for spillway bulkheads.
(4) Recess (slot) armor plates, bearing plates, seal
plates, and guide plates for vertical-lift spillway gates and
spillway bulkheads serve as true vertical bearing surfaces
to transfer gate or bulkhead water load to concrete; serve
to seal in conjunction with rubber “J” seal on each end of
gate or bulkhead; serve to protect concrete in and adjacent
to the gate or bulkhead recesses (slots) from damage
during installation and removal activities; and serve as
contact rolling and positioning surfaces.
(5) The trunnion anchorage assembly is used with
prestressed concrete trunnion girders for tainter gates.
(6) The gate hoist machinery frame (exposed frame
with embedded anchor and adjusting bolts and grout support) serves as a level base and support for hoist machinery and components.
(7) Service bridge embedded metals include crane rail
anchorage and hand rail anchorage.
(8) Other miscellaneous embedded steel items are
used for bulkhead dogging devices, concrete corner
protection, grating supports, handrail supports, stair treads,
ladder supports, tainter gate stops, and mooring rings and
check posts.
c. Material. The most durable and long-lasting materials must be chosen for embedded metals--especially for
metals that are continuously submerged--such as anchor
bolts and nuts, horizontal seal and sill plates, curved and
vertical seal and bearing plates, recess (slot) armor and
guide plates, wicket gate components, drum gate components, hinged-crest gate components, etc. Embedded
items whose surfaces serve only for armoring protection
a. General. This section will provide a broad overview of mechanical and electrical equipment with a brief
description of the functions of the various items.
b. Mechanical and electrical. The major mechanical
and electrical features for a navigation dam include the
(1) Hoist machinery for spillway gates. As an
example, the gate hoists for a tainter gate will consist of
two fixed units, one at each end of the gate, located near
the top of the piers. These units will be driven by one
electric motor mounted on one of the units. The drive
unit and the driven unit will be coupled together by a line
shaft or a torque tube extending between the two units.
The drive side will have the electric motor, two bull
gears, speed reducers, cable drum, and a brake. The
driven side will have two bull gears, speed reducers, and
a cable drum or chain rack. All these items will be
mounted on a structural steel frame. The electric motor
horsepower required will be determined by the requirements of EM 1110-2-2702.
The operation of the
individual gate hoist motors will be controlled by a
pushbutton-type master control station located near each
drive unit. Remote operation of the hoists can also be
provided. For complete details of hoist mechanical and
electrical features, see EM-1110-2-2702. See Plate 20 for
a typical layout of hoist machinery. In Europe, gates are
raised or lowered with hydraulic cylinders instead of
cables. This type of design should be considered.
(2) Operating machinery for wicket gates and
hinged-crest gates. Typical machinery will usually be
hydraulic and will consist of a hydraulic power unit,
hydraulic cylinder, operating rod, linkage to structure, and
torque tube. One hydraulic pump may serve one or more
cylinders with valving that would allow directing pressure
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to other cylinders in the system. The Olmsted wicket
dam on the lower Ohio River is an example of this type
of hydraulic system. Dam No. 3 on the Red River in
Louisiana has a single hinged-crest gate, which is
operated by a hydraulic cylinder arrangement at each end.
Electric power must be provided to all hydraulic pumps.
(3) Traveling gantry crane. Traveling gantry cranes
are sometimes used for installing and removing vertical
spillway gates, vertical bulkheads, and sectional bulkheads. Necessary electric power is supplied to the gantry
crane by either power takeoff rails or a retractable power
cable on a reel. Procurement of this crane will be by a
dimensional requirement drawing and a performance
(2) The wicket gate operating machinery needs to be
located in a watertight gallery. The hinged-crest gate
machinery needs special support and operating space at
each end of the gate for housing of hydraulic cylinders
and crank mechanisms.
(3) Both the traveling gantry crane and traveling
hoist car need a high service bridge with crane rails to
travel on for performing spillway gate and bulkhead
installation and removal procedures.
(4) The sluice gates and operators require a watercarrying conduit through the dam. Also required are
sluice gate access galleries, operating rooms, shafts, and a
bulkhead shaft extending to the top of the dam.
(4) Traveling hoist car. The traveling hoist car is
used for transporting, installing, and removing spillway
sectional bulkheads. Electric power is supplied to the
hoist car via power takeoff rails. Procurement is by the
same method as for the gantry crane.
(5) The gallery pumping system must have gutters in
the drainage gallery which collect and direct water to a
sump pit adjacent to the gallery room containing the
pump. There must also be a pump discharge pipe to the
lower pool.
(5) Sluice gates and operators. Operators may be
needed for raising and lowering sluice gates. A limited
number of sluice gates are used on navigation dams.
When they are provided, they will be used for minimumflow water quality releases, discharges to attract fish, or
drawdown of the reservoir in an emergency situation.
Electric motors are used for operating power. Some large
sluice gates will be hydraulically operated. Also, large
sluice gates are usually installed in pairs on a single conduit for operational safety, inspection, and maintenance
purposes. Upstream bulkhead slots may also be provided.
13-18. Catwalks
(6) Sump pumps. Sump pumps are used for pumping
water from the drainage gallery sump and discharging the
water into the lower pool.
13-19. Dam Lighting
c. Effects on concrete structures. The above items
influence the concrete structure layout and design requirements in a variety of ways.
(1) A tall pier is required for the spillway gate hoist
machinery in order to operate the gate through its
designed range of travel. Also, it is desirable to provide a
machinery house or cover in certain cold climates. The
line shaft connecting the hoist machinery on adjacent
piers can often be supported by brackets or cantilevered
steel members fastened to the service bridge or to catwalk
framing. If the layout is not suitable for this arrangement,
a self-supporting torque tube must be used in lieu of the
line shaft.
Structural steel personnel catwalks will need to be
provided on navigation dams when there is no other practical means of access to project features that require
periodic inspection, adjustment, greasing, painting, or
other maintenance as well as possible replacement. Galvanized steel framing, handrail, and grating will normally
be used. Design live loading should be at least 100 lb/sq
ft with localized loads of the heaviest equipment or
machinery expected possible on the structure.
Lighting facilities need to be provided for use by operating personnel and maintenance, inspection, and emergency
crews, and for the benefit of navigation interests. Lighting will be required for the following areas: stairwells in
bridge piers, galleries and access shafts, service bridge
roadway, piers (exterior), machinery house interiors, spillway gate bays, crane and hoist cabs, fixed weir, signal
lights, and warning signs. Reference ER 1130-2-306 and
EM 385-1-1. Enclosed spaces such as stairwells, galleries, access shafts, crane and hoist cabs, and machinery
houses need to have good lighting for use by operating,
inspection, and maintenance personnel. Switches should
be conveniently located and readily available at adits so
as not to have to be searched for in the dark. Some type
of additional low-level emergency lighting could be considered for galleries. Service bridge roadway lighting can
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be pole-mounted on the machinery house at each pier. If
a machinery house is not used at the service bridge roadway level, the lighting can be mounted either on the roadway guardrail or on poles. Exterior pier lighting will
include upstream and downstream floodlights and floodlights on each pier face for lighting the spillway bays.
Upstream and downstream signal lights should be
mounted as high as possible on the dam structure. The
number required will depend on the specific project layout. Upstream- and downstream-oriented searchlights
should be mounted high on the piers or bridge roadways
at locations readily accessible to operating personnel. The
number required will depend on the specific project
requirements. Some navigation dams have fixed overflow
weirs which need to have some lighting. This can be
achieved by a floodlight on the face of the adjacent pier
at one end and a pole-mounted floodlight at the other end.
13-20. Lightning Arrestor System
A sufficient-size grounding cable should be provided to
connect all machinery, electrical apparatus, conduits, conduit supports, crane rails, hand railing, spot and floodlights, lighting standards, and all extensive exposed metal
items to a ground mat or ground rods for protection of
equipment and personnel. Some projects have also provided for protection of the dam and its metal features
from potential direct lightning strikes. The lightning
protection system is composed of several tall poles
located on the highest point of the dam structure and
connected by metal cables which are tied into the above
grounding system. This type of lightning protection system was used on some of the Red River Waterway projects in Louisiana.
13-21. Cathodic Protection
All major structural steel structures which are submerged
need to be provided with cathodic protection such as
sacrificial anodes or the impressed current type to prevent
corrosion. Submerged recess armoring, bearing plates,
seal plates, etc., need to have cathodic protection when
they are composed of dissimilar metals--stainless steel in
combination with carbon steel, for example. When steel
sheet piling is used as part of a fixed weir or other permanent structure, some type of protection should be provided
at the water line, where the piling is constantly subjected
to wetting and drying due to wave action. Some height of
this piling, above and below the water line, should have
corrosion protection. If cathodic protection is not used,
then a durable coating such as bitumastic or an increased
steel thickness should be used.
13-22. Surveillance Systems
Television transmitters with appropriately located television screens (receivers) should be provided on dams so
that the facility may be operated safely and efficiently. In
planning surveillance systems, the designer should consult
persons with experience and expertise in this technology-especially the latest state-of-the-art equipment available.
For convenience of maintenance, the equipment chosen
should be of standard types and reliable design. Choosing
similar standardized equipment for all dams in a navigation system will allow for interchange of parts and equipment and reduce the supply of spare parts and equipment
required in inventory. Television surveillance is especially useful in cases of remote operation of the spillway
gates when recreational boats and fishing boats are likely
to be in the water either upstream or downstream of the
dam. Television surveillance will usually be supplemented by warning sirens or horns plus warning signs.
13-23. Waterstops
Waterstops prevent the migration of water through joints
of dams. A double line of waterstops should be provided
near the upstream face of the dam at all joints. For gated
spillway sections the tops of waterstops should terminate
at gate sills and tie in to embedded steel if provided. If a
sheetpile cutoff is provided below the monolith, the waterstop should tie in to the sheetpile at monolith joints. A
single line of waterstops should be placed around all
galleries and other openings crossing monolith joints.
Further guidance in the selection and use of waterstops
can be found in EM 1110-2-2102.
13-24. Joint Materials
Dam structures are subject to volume changes due to
temperature, moisture content, and chemical reaction.
Adjacent monoliths may experience differential movement
at joints due to exterior loading. To minimize these
effects and preserve the integrity and serviceability of the
structure, joints should be provided. The introduction of
joints creates openings which must be sealed. Typical
joint filler materials consist of a variety of substances and
configurations, depending on the purpose of the filler.
Detailed guidance in the selection and use of joint
material can be found in EM 1110-2-2102.
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Appendix A
A-1. Required Publications
PL 91-190, National Environmental Policy Act (NEPA)
National Historic Preservation Act
Public Law 99-662
TM 5-809-1
Structural Design Criteria for Loads
ER 1105-2-100
Guidance for Conducting Civil Works Planning Studies
ER 1110-2-1404
Hydraulic Design of Deep Draft Navigation Projects
ER 1110-2-1458
Hydraulic Design of Shallow Draft Navigation Projects
ER 1110-2-1461
Design of Navigation Channels Using Ship-Simulation
ER 1110-2-1806
Earthquake Design and Analysis for Corps of Engineers
ER 1110-2-8152
Planning and Design of Temporary Coffer Dams and
Braced Excavation
EM 1110-2-1601
Hydraulic Design of Flood Control Channels
EM 1110-2-1602
Hydraulic Design of Reservoir Outlet Works
EM 1110-2-1603
Hydraulic Design of Spillways
EM 1110-2-1604
Hydraulic Design of Navigation Locks
EM 1110-2-1605
Hydraulic Design of Navigation Dams
EM 1110-2-1611
Layout and Design of Shallow-Draft Waterways
EM 1110-2-1612
Ice Engineering
EM 1110-2-1901
Seepage Analysis and Control for Dams
EM 1110-2-1902
Stability of Earth and Rock Fill Dams
EM 1110-2-2000
Standard Practice for Concrete for Civil Works Structures
EM 1110-2-2102
Waterstops and Other Joint Materials
EM 1110-2-2104
Strength Design for Reinforced-Concrete Hydraulic
ER 1130-2-306
Navigation Lights, Aids to Navigation, Charts, and
Related Data Policy, Practices and Procedures
EM 1110-2-2200
Gravity Dam Design
EP 25-1-1
Index of Publications
EM 1110-2-2300
Earth and Rock-Fill Dams General Design and Construction Considerations
EM 385-1-1
Safety and Health Requirements Manual
EM 1110-1-1904
Settlement Analysis
EM 1110-2-2400
Structural Design of Spillways and Outlet Works
EM 1110-2-2502
Retaining and Flood Walls
EM 1110-1-1905
Bearing Capacity of Soils
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EM 1110-2-2503
Design of Sheet Pile Cellular Structures Cofferdams and
Retaining Structures
EM 1110-2-2602
Planning and Design of Navigation Lock Walls and
EM 1110-2-2701
Vertical Lift Crest Gates
EM 1110-2-2702
Design of Spillway Tainter Gates
EM 1110-2-2901
Tunnels and Shafts in Rock
EM 1110-2-2906
Design of Pile Foundations
EM 1110-2-3506
Grouting Technology
EM 1110-8-1(FR)
Winter Navigation on Inland Waterways
ETL 1110-2-256
Sliding Stability for Concrete Structures
U.S. Army Engineer District, Pittsburgh 1986
U.S. Army Engineer District, Pittsburgh. 1986. “After
Action Report - Monogahela River Barge Breakaway
Incident - November 1985,” 1000 Liberty Ave., Pittsburgh, PA 15222.
U.S. Army Engineer District, Pittsburgh 1991
U.S. Army Engineer District, Pittsburgh. 1991. “After
Action Report - Monogahela Barge Breakaway Incident January 1990,” 1000 Liberty Ave., Pittsburgh, PA 15222.
ER 1110-8-2(FR)
Inflow Design Floods for Dams and Reservoirs
EM 1110-2-1906
Laboratory Soils Testing
EM 1110-2-1907
Soil Sampling
EM 1110-2-1908
Instrumentation of Earth and Rock-Fill Dams (Part 1)
ETL 1110-2-338
Barge Impact Analysis
ETL 1110-2-365
Nonlinear Incremental Structural Analysis of Massive
Concrete Structures
Guide Specifications for Steel Sheet Piling
Headquarters, U.S. Army Corps of Engineers 1986
Headquarters, U.S. Army Corps of Engineers. 1986.
“Uniform Federal Accessibility Standards (UFAS),”
Washington, DC.
Shore Protection Manual (SPM) 1984
Shore Protection Manual (SPM). 1984. 4th ed., 2 Vols,
U.S. Army Engineer Waterways Experiment Station,
Coastal Engineering Research Center, U.S. Government
Printing Office, Washington, DC.
A-2. Related Publications
EM 1110-2-4300
Instrumentation for Concrete Structures
Fletcher 1993
Fletcher, B. P. 1993.
Model Investigation,”
U.S. Army Engineer Waterways Experiment Station,
3909 Halls Ferry Road, Vicksburg, MS 39180.
EM 1110-2-1908
Instrumentation of Earth and Rock Fill Dams (Part 2)
EM 1110-2-1911
Construction Control for Earth and Rockfill Dams
EM 1110-2-2105
Design of Hydraulic Steel Structures
EM 1165-2-303
Conservation Pools in Reservoir Projects
ETL 1110-2-352
Stability of Gravity Walls, Vertical Shear
“Baldhill Spillway, Hydraulic
Technical Report HL-93-6,
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Appendix B
Design and Construction Planning
B-1. Introduction
Information provided in Appendix B of EM 1110-2-2602
contains guidance on structural and project engineering
responsibilities as well as details of the life cycle project
management process as applied to a large scale civil
works project. This guidance is also applicable to navigation dams. A reiteration of the structural and project
engineering responsibilities is provided below.
B-2. Structural and Project Engineering
a. General. The Corps of Engineers operates in
partnership with the Inland Waterways User Board
(IWWUB), which shares the cost of designing and building navigation lock projects. Increased emphasis is being
place on the key roles of the structural engineer (SE) and
the project engineer (PE) in achieving high-quality products on schedule and within budget. To facilitate project
development, a project management office was established
in HQUSACE and in each division and district. In the
project management system, the project manager (PM) is
the primary point of contact for project coordination
between the local sponsor and the Corps. The PM manages the project scope, schedule cost, and budget, and
facilitates the resolution of existing or potential problems.
The PM is also responsible for reporting the project’s
status to higher authorities and the local sponsor. This
guidance should enable the SE and PE position to better
support the PM. An important link in the cooperative
relationship between engineering division (ED) and the
PM is the individual designated as the PE. This individual should be a registered professional engineer and
should be an SE in the case of a navigation lock project.
However, the PE could come from other technical disciplines in ED. The PE position should not be filled by any
other technical manager (TM). One PE is assigned to the
overall project. The PE’s role on the design team is to
assist in the technical management of the project.
Because a successful PE generally requires broad design
experience and technical leadership, such assignments
must be made to senior designers who have been delegated authority to perform their interdisciplinary
b. Structural engineering responsibilities. Structural
design is a creative process that generally begins with a
vague definition of the client’s problems and proceeds to
a practical solution using basic engineering principles and
modern technology. A navigation lock project is executed
by a multidisciplinary team that may include several
structural engineers. The SEs must determine the appropriate level of analysis required for each phase of the life
cycle process. The analysis performed during the reconnaissance phase relies on engineering judgment with
abridged numerical modeling. During this phase, the SEs
will examine a minimum number of possible structural
solutions that are mutually acceptable to local and federal
interests. In contrast, during the preconstruction engineering and design phase, detailed analyses will be performed
and structural features designed to the degree necessary to
prepare quality contract documents. During the construction phase, the only analyses performed are those required
to resolve field problems. Analyses during the operation
and maintenance phase may be required for deficiencies,
repairs, modifications, or replacement. The responsibilities for the structural design can be categorized as
described below.
c. Design and analysis. One of the SE’s primary
responsibilities is to develop a structural solution that
meets the design objectives. The SE will draw upon past
experience to develop design concepts or examine new
and innovative solutions. The SE will combine engineering judgment with engineering principles to develop a
reliable basis for design. Depending on the project phase,
the analyses may require manual computations that capture the general structural behavior or in-depth computer
modeling using software developed by the ComputerAided Structural Engineering (CASE) project.
d. Design quality. The engineering design team’s
performance influences the quality of each design phase.
Quality is affected by the SE’s ability to communicate,
apply sound judgment, advise, plan, analyze, and review
e. Cost estimating. The SE should help develop the
cost estimate at each phase of the project. The level of
this participation may vary; at whatever level, it is essential to developing a reliable cost estimate. (Public Law
99-662 limits projects authorized by the act to a 20 percent increase in the baseline cost, excluding increases due
to inflation and changing legal requirements.) The SE
should consider the reliability of engineering and other
data available when developing contingency factors.
f. Design schedule and budget. Throughout the
project’s life, SEs should prepare and maintain their
design schedules and budgets.
This information is
provided to the PE for preparing the engineering schedule
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and budget. Individual schedules and budgets should be
based on reliable data and information available from
other disciplines. Contingencies should be included to
account for uncertainties. An overly conservative budget
or design schedule can result in termination of the study
or require reauthorization of the project. On the other
hand, overly optimistic estimates result in insufficient
funding to complete the project. After the schedule and
budget are approved, the SE should complete the design
within that schedule and budget. Changes can be made
only with written approval by the PM. Throughout the
project, the SE should make comparisons between scheduled and actual progress, and budgeted and expended
dollars, to assess performance. The SE should provide
the results of these comparisons to the PE.
g. Technical coordination. The SE is involved in
technical coordination of structural features during all
project phases. The SE should coordinate structural
design activities with individuals from other functional
elements (geotechnical, hydraulic, mechanical, electrical,
architectural, construction, operations, cost engineering,
real estate, surveying, mapping, etc.) to develop the
design of the structural features. Also, the SE should
maintain technical coordination with the technical staff of
the local sponsor. Technical coordination with a higher
authority to reach early agreement on unprecedented or
complex problems is encouraged.
h. Project engineering responsibilities. Selection of
the PE is one of the most important management decisions for ensuring success. The PE should be a technical
leader who has an overview of the project and a general
understanding of the various functional elements and thus
is able to support the PM by managing the design
(1) Management of design process. The PE, working
with all appropriate disciplines, should define the engineering design objectives pertaining to customer care,
innovation, engineering and design (E&D) costs, operation
and maintenance (O&M) costs, modifications, quality,
biddability, constructibility, and operability. The PE
should identify the specific tasks required to support the
design objectives and should integrate the team effort in
an efficient and cost-effective manner. The PE should
monitor team progress by reviewing the schedules and
budgets and by measuring actual production, time elapsed,
and funds expended. Changes should be documented and
evaluated for impacts.
to promote a team environment that encourages
communication between engineering disciplines. The PE
must recognize technical conflicts at an early stage. In
addition, the PE should explore alternate designs that
could improve quality or reduce costs.
(3) Design schedule and budget. The PE should
coordinate and consolidate the budget and provide it to
the senior engineering staff. Each discipline should prepare a detailed estimate to ensure that adequate resources
are budgeted to perform all engineering functions for all
(4) Cost estimate. The PE should ensure that quantities are being developed in accordance with the code of
accounts so that no quantities are omitted or duplicated.
Contingencies should be established and justified in terms
of available information. The PE should inform the PM
if additional engineering information is needed to reduce
contingencies that have a significant impact on total cost.
A sample template for making the cost estimate with
typical-cost items for a navigation dam is provided in
section B-4.
(5) Interaction with project manager. The PE should
maintain a working relationship with the PM. It is essential that the PE inform the PM about the project status
and contacts with the local sponsor. The PE should support the PM in developing the engineering aspects of the
project management plan.
B-3. Design Checklist for Navigation Dams
a. Reconnaissance report. Structural analysis in this
phase is usually limited to a few basic calculations used
together with data from similar projects and proven engineering concepts to establish the project’s viability.
(1) Approximate location and consideration or list of
alternative sites.
(2) Preliminary determination of controlled and
uncontrolled dam width.
(3) Need for navigation pass.
(4) Lift.
(5) Need for model studies.
(6) Preliminary foundation type (for cost purposes).
(2) Design quality. A quality product is the primary
objective. Design quality is influenced by the PE’s ability
(7) Preliminary spillway configuration.
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(8) Overall structural layout of dam and appurtenant
features that is a reliable base for the cost estimate.
(7) Establish requirements for operations buildings
(control stands, etc.).
(9) Preliminary decision on type of gates (for cost
Decide on maintenance unwatering facilities.
Compute quantities for feasibility cost estimate.
(10) Need for a bridge.
(10) Establish preliminary design criteria.
(11) Estimate of design effort required for feasibility
(11) Establish list of guide specifications.
(12) Preliminary quantities for reconnaissance cost
(12) Provide input for:
• Outline of VE studies.
(13) Estimate-design criteria.
• Detailed schedule and budget for E & D.
(14) List of design memoranda.
• Project Management Plan (PMP).
(15) E & D cost estimate (input).
(13) Describe special analyses or Feature Design
Memoranda (FDM) required.
(16) Coordination with other elements as needed.
b. Feasibility report. A significant amount of structural analysis is accomplished during this phase. The
design team examines and compares alternative solutions
and then chooses the most suitable and economical solution. Sufficient structural analysis must be performed to
ensure that the chosen solution is the appropriate one and
that quantities are reliable enough to predict the construction cost within 20 percent.
(14) Coordinate with other elements as needed.
c. Design memorandum (DM) phase. Most of the
structural analysis will be performed in the DM phase.
The design of all the representative structural components
should be accomplished in the individual DMs as identified in the PMP. The DM should address the following
(1) Need for detailed soil information.
(1) Finalize location.
(2) Determine
(2) Final design criteria.
(3) Final loads.
(3) Determine overall dam geometry:
(4) Loading conditions and critical cases.
• Elevations of spillway crest, navigation pass,
and bridge, length of spillway, etc.
(5) Final structural analysis of all gates, bulkheads,
• Width of dam piers.
• Type of gate and control elevations such as
elevation of trunnion girder.
(6) Structural analysis and determination of areas of
steel for all critical reinforced concrete members.
(7) Layout of dam accessories and embedded metals.
(4) Finalize type of foundation.
(8) Parapet-versus-hand-rail selection.
(5) Select type of lock gates based on functional
(6) Select type of filling and emptying system.
(9) Public access.
(10) Esplanade.
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(11) Control houses.
(12) Level of coverage for FDM presentation.
(13) Drawings to be presented in FDM and what will
be shown on each.
finalize the design. This phase consists mainly of designing the details, placing them on the drawings, and writing
the specifications.
(1) Identify standard details to be used.
(2) List all drawings and what to present on each.
(14) Preparation of FDM drawings.
(3) Identify all details remaining to be designed.
(15) Proposed instrumentation relative to structural
(4) Prepare reinforcing steel layouts.
(16) Preparation of FDM text.
(5) Prepare contract drawings.
(17) Quantities for FDM cost estimate.
(6) Research previous similar jobs for specifications.
(18) Input for Critical Path Method (CPM) on materials and equipments.
(7) Mark up guide specs and specs from other jobs.
(8) Write specifications as required.
(19) Coordination with other elements as needed.
(9) Prepare quantities for government estimate.
d. Plans and specification phase (PED). In this
phase, the team performs minimal structural analysis
(main structural members) besides revisions needed to
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B-4. Detailed Cost Estimate
Excavation, common
Excavation, rock
Excavation, foundation
Deep compaction of
foundation fill
Fill, backfill
Piling, steel bearing
HP 14x73, vertical
HP 14x117, vertical
HP 14x117, batter
Pile tips for HP 14x73
Pile tips for HP 14x117
Steel, reinforcement
(welded to tension pile)
Pile load and driving tests
Piling, steel sheet (PZ22)
cu yd
cu yd
cu yd
cu yd
lin ft
lin ft
lin ft
lin ft
Subtotal for Foundation
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DAM, Continued
Concrete, reinforced
Dam monolith bases
Dam piers
Service bridge piers
Non-overflow walls
Stilling basin
Steel, concrete
Preformed joint filler
cu yd
cu yd
cu yd
cu yd
cu yd
cu yd
lin ft
sq ft
Subtotal for concrete structure
Steel, tainter gates
Steel, emergency
Steel, maintenance
Steel, miscellaneous,
Line hooks and mooring rings
Subtotal for structural steel
Concrete, precast I-Beams
Concrete Reinforcement
Subtotal for Service Bridge
cu yd
lin ft
lin ft
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Appendix C
Lessons Learned - Case Histories
C-1. General
This appendix will review some of the major and minor
problems that have been experienced on navigation dam
projects designed and built prior to 1993. Also, references will be given to Corps districts and divisions and
other Corps organizations involved and to published
material which relates to a specific problem and the
follow-up action taken.
C-2. Concrete
Several Corps districts have experienced problems with
concrete durability in stilling basins and buckets, apparently due to below-average-quality concrete, insufficient
reinforcing steel, and the abrasive action of ice, drift,
gravel, stones, etc., carried in the spillway discharge
water. The damage to the concrete has varied from surface abrasions to loss of enough concrete to expose the
reinforcing steel, which originally had 4 in. or more of
cover. The Pittsburgh and Nashville districts have experienced problems of this type. Not much can be done
about the materials carried in the spillway discharges, but
current engineering manuals have updated concrete quality
(higher strength, more durable aggregates, etc.) and reinforcing steel guidance to prevent most problems of this
type. Refer to Chapter 12 for further details. Since it is
not possible, on most projects, to unwater the spillway
bucket for repair without using extremely costly steel pile
cofferdams and, during high flood flows, interfering with
spillway discharges, it is highly desirable to follow the
published design criteria and guidance for stilling basin
concrete and reinforcing.
C-3. Spillway Tainter Gates
a. Use of submergible gates. When the first of the
“current generation” Ohio River navigation dams were
designed and built in the 1950s and 1960s, it was deemed
advisable to use double-skin plated overflow tainter gates
(submergible gates) for the purpose of passing ice and
debris through some of the spillway bays at a project.
The other spillway bays would also have similar doubleskin plate gates, but they would rest on the sill and would
not be submergible. Vibration problems, in addition to
horizontal sealing problems at the sill, developed on the
submergible gates from the beginning of their operation.
It was also discovered that these gates were not satisfactory for passing ice and/or debris unless almost fully
lowered--a condition which could cause damage to the
stream bed stone protection downstream of the stilling
basin. After several years of unsuccessful attempts to
solve the vibration and seal problems, the Corps adopted a
policy of not using submergible tainter gates on future
projects. Many of the submergible tainter gates remain in
use on Ohio River navigation dam projects, but they are
no longer operated as submergible gates. It was discovered that ice and debris could be passed satisfactorily
through the spillways by raising the gates off the sill a
sufficient distance to create enough discharge velocity to
draw the ice and debris to and through the spillway bay
underneath the gate. At Cheatham Dam on the Cumberland River in the Nashville district, the seven submergible
tainter gates were modified to be nonsubmergible and to
rest on a modified sill with a new ogee crest shape. The
costs of the modifications at this project were almost
balanced out by the revenue from additional power generated by savings in water losses (leakage) where the submergible gate failed to seal at the horizontal sill. The
Huntington, Pittsburgh, and Louisville districts have background information on the problems and actions taken on
the submergible gates on the Ohio River.
b. Passing of ice and debris. In addition to the
submergible tainter gates described in paragraph C-3a
above, the Corps has used “piggy-back” tainter gates on
some projects in the Pittsburgh district. These gates are
composed of an upper section and a lower section which
operate independently of each other, the intent being to
raise the upper section out of the water and thus allow ice
and debris to pass over the lower section which remains
in place on the sill. This arrangement has not proved
satisfactory, however, and recent tainter gate designs have
not used the “piggy-back” concept.
c. Cables (wire ropes) versus chains. Link chains
for use in raising and lowering spillway tainter gates are
composed of links, pins, spacer sleeves, spacer washers,
racking collars, and retaining rings. The holes in the links
and pins are machined to specific tolerances to allow easy
movement of the link with relation to the pin. Links and
pins are made of 4140 steel. Pins have been cadmium
coated and chain-bearing surfaces coated with graphite
lubricant during assembly. No grease grooves or grease
fittings are provided for the pins; thus, all greasing of the
pins and links has to be by manual application to exposed
surfaces. These chains function well with no special
problems for that portion that stays out of the water where
normal maintenance and greasing can be done readily on
a periodic basis. However, the portion of the chain that is
continually submerged is subject to corrosion and pitting
damage and can become less flexible and possibly
EM 1110-2-2607
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inoperative due to infrequent maintenance and greasing of
the pins. The Nashville district experienced many operational and maintenance difficulties with the chains on the
Cheatham Dam tainter gates, and eventually all the portions of the chains that were continually submerged had to
be replaced. The replacement links and pins were made
of AISI 4140 steel and had basically the same components except that copolymer washers were added on each
side of all links. Also, each new pin was provided with
three grease grooves and three grease fittings to allow
lubrication of the pin-link contact surfaces. Chains were
used exclusively until manufacturers developed a wire
rope which could be wound on itself. These stainless
steel wire ropes have proven to be much better from an
operational and maintenance standpoint, and all new projects will use wire rope for tainter gate hoisting operations. For more information on stainless steel rope, see
EM 1110-2-2702.
d. Treatment of bottom lip of tainter gates. Several
Corps districts have experienced problems with the shape
of the bottom lip of tainter gates, as well as problems
with horizontal rubber seals used on the lip to provide a
more positive seal at the sill.
(1) Shape of lip. The relatively broad shape of the
lip of the gates at Barkley Dam on the Cumberland River
in the Nashville district, coupled with an attached flat
rubber sill seal and seal retainers, caused gate vibrations
for a range of gate openings and tailwater levels. Investigations by the Nashville district, aided by WES, resulted
in removal of the rubber seals and retainers and grinding
of the bottom of the gate to obtain a satisfactory metal-tometal seal. A report on this specific situation is available
from WES. For new applications, emphasis is placed on
making the lip of the gate as sharp as possible so that
negative pressures, which can cause gate vibrations, are
not created.
(2) Rubber seal on lip of tainter gate.
(a) The navigation dams on the Arkansas River in the
Little Rock district had tainter gates which were equipped
with horizontal rubber “J” seals, mounted on the gate lips
for gate sealing at the sill level. Use of these “J” seals
resulted in gate vibration problems when the gates were
opened to pass water. These vibration problems were
essentially solved by removing the seal and retainers. A
WES report of its investigations and the resulting
remedial actions is available. Experience and knowledge
gained in the above two instances and from WES model
tests indicate that the use of rubber seals of any type on
the lips of tainter gates could result in excessive gate
(b) In most cases, an adequate metal-to-metal seal
between the lip and sill can be obtained by proper adjustment (grinding) of the lip to precisely match the sill plate.
However, if it is necessary to conserve every bit of water
possible, a properly designed flat rubber seal assembly
similar to that used on the Red River (Louisiana) dams
tainter gates may be provided after proper coordination
with and recommendations from WES and district
hydraulic engineers. Rubber “J” seals should not be used
at this particular gate lip location.
(3) Excessive leakage at lip of gate. The Cordell
Hull navigation dam on the Cumberland River in the
Nashville district has conventional tainter gates with
ASTM A-36 steel lips that rest on embedded stainless
steel sill plates. Because river flows are normally routed
through the power plant adjacent to the spillway, the
tainter gates are only off the sill when they are opened to
pass flood flows. After the project had been in operation
for several years, it was noticed that the gates had excessive leakage at the horizontal lip-sill contact. One gate
was unwatered for inspection by using the spillway bulkheads, and a badly worn lip was revealed. The deterioration of the lip was judged to be due to lack of cathodic
protection on the gates, and erosion-corrosion plus some
cavitation. In order to remedy this situation, a stainless
steel lip was installed on the gate and carefully adjusted
for a better seal contact with the embedded stainless steel
sill plate. Cathodic protection was also installed on the
e. Side seals and rubbing plates for tainter gates.
Molded rubber “J” seals have proven to function very
efficiently as side seals for spillway tainter gates. However, when these seals were used with ordinary structural
steel (ASTM A-36) embedded rubbing plates, the seals
would frequently suffer damage if any undue offsets,
irregularities, or heavy rusting was present on the steel
rubbing surfaces. Also, the seals were subject to considerable wear as they slid along the steel plate, due to the
high friction factor of the rubber. On some Corps projects, maintenance and/or replacement of the seals was
considered to be too frequent. To remedy this undesirable
situation, two things were done:
(1) The side seal rubbing plate was specified to be
made of either stainless steel or stainless clad steel.
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(2) The ball of the rubber “J” seal was provided with
a teflon coating so that the teflon, and not the bare rubber,
contacted the side seal rubbing plate. The teflon coating
in this application has functioned well and is very durable.
It also has a friction factor of about one tenth that of bare
rubber. The successful use of these two items makes it
highly desirable that all future Corps projects seriously
consider using stainless steel side seal rubbing plates with
teflon coated rubber “J” seals for spillway tainter gates.
Dams--Louisiana-Vicksburg district. It has also been
emphasized by experience and by WES model studies
that, in some cases, streambed scour protection is essential
during construction to prevent excessive scouring of the
streambed material. This is especially true when a steel
pile cofferdam is in place and the river flows through a
limited opening.
C-4. Streambed Scour Protection
a. Steel sheet pile tees and wyes. Welded, in lieu of
riveted, steel sheet pile tees and wyes, which were used
quite often in the construction of steel pile cells for cofferdams, did not prove suitable because of failures of
some welds during driving of these items. The failures
were probably due to the fact that the pile material was
not of weldable quality, coupled with the high impact on
the tees and wyes when they were driven. Subsequently,
the Corps took the lead in developing an alternative
extruded wye section. However, this extruded wye was
used only for a few years and then abandoned. The section was very compact, which resulted in its being very
limber and difficult to handle and drive in long lengths.
Splicing of the wyes was also not practical. After this,
the Corps adopted a policy of using only riveted or highstrength bolted tees and wyes.
One of the most important features of a navigation dam
project is the streambed scour protection that must be
provided downstream of the concrete dam structure.
Several Corps projects have experienced near-catastrophic
situations due to failure of the stone protection to function
as intended. Some of the projects had failures during
flood conditions, and others had gradual progressive failures over a long period of time. After many years of
operation, Dams 52 and 53 on the Ohio River in the
Louisville district developed scour holes over 100 ft deep
in the streambed downstream of the navigable pass dam
sill after the scour protection failed. One section of
Dam 52 actually had some downstream movement but did
not fail. The overall remedial action required to prevent
potential failure of these two dams consisted of filling the
scour holes with large stone at a cost of several million
a. Model tests and studies. Model tests are very
helpful in determining the extent and location of scour
protection required downstream of a navigation dam structure. In some cases, histories of prototype experiences
and required remedial measures are also very helpful in
assessing scour protection needs for new projects. Studies
of these past experiences have revealed that conservative
designs are advisable. Chapter 5, paragraph 5-11 of
EM 1110-2-1605 covers the design of downstream
streambed protection. See also Chapter 8, Channel Protection, in this manual. Paragraph 8-5 of EM 1110-21605 covers rehabilitation methods for failed scour
protection in detail, and paragraph 8-6 gives a tabulation
of model studies conducted to evaluate major rehabilitations required as a result of scour protection failures at
several Corps projects.
b. Other information. Other pertinent information
concerning major problems with scour protection at Corps
projects is available as follows: Old River Control
Structure--Louisiana-New Orleans district; Dams 52 and
53, Ohio River--Louisville district; Red River Dams-Louisiana-Vicksburg district; and Jonesville and Columbia
C-5. Cofferdams
b. Use of new and used steel sheet piling. In the
early stages of construction, it is advisable to use only
new sheet piling because of the considerable risk and
liability associated with sheet piling that has inadequate
interlock strength or anomalies in the interlocks that cause
them to fuse during driving. Use of piling that has been
used on two previous projects is subject to approval of
higher authority. However, where staged construction is
to be used, plans should include reuse of sheet piling in
later stage cofferdams, taking the precautions described
c. Inspection of used piling. Any steel sheet piling
that is to be reused in a subsequent cofferdam should be
carefully processed and inspected after it is extracted.
The important items in processing and inspecting each
sheet of the piling for reuse are as follows: proper
handling and storage so that permanent bends are not
introduced into the piling and the piling is not damaged to
the extent it cannot be reused; visual inspection of the pile
webs for any undue rusting, nicks, tears, and splits, and
either rejection of the entire sheet or removal of the damaged portion; visual inspection of the interlocks for any
damage due to handling, driving, or extraction that would
be cause for rejection; gaging of the full length of all pile
interlocks with a metal gage to ensure that the
EM 1110-2-2607
31 Jul 95
configuration of the interlock is within allowable limits to
properly grip the adjoining interlock and develop the
proper interlock strength; load testing of coupons from the
piling if required to calibrate gaging operations; and
reduction of the allowable interlock tension to a
conservative value.
C-6. Markland Incident of 1967
This incident resulted from a barge tow breaking loose
from an upstream mooring (tied to a tree on the bank that
pulled out) and floating into the dam. The barges sank in
the dam gate bays with some of the barges wrapping
around the piers, preventing the tainter gates from closing during a return from open river conditions. The
resulting loss of pool caused major damage to harbors,
stranded boats, sloughed highway embankments, and
exposed water intakes and sewer outfalls. Figure C-1
shows the removal of one barge from the Markland Dam.
Based on this incident, the Corps developed recommendations for future applications as summarized in the following paragraph.
C-7. Summary of Recommendations Based on
the Markland Incident
The following edited version of the recommendations
contains guidance that relates to the lock and dam design
and operation.
a. Prevention of accidents -- lock and dam.
(1) Recommend installing remote control systems to
provide for operation of spillway gates from the operations building.
(2) Recommend that Corps of Engineers Regulations
prohibit operators from mooring unattended tows within
10 river miles upstream of a dam, except at commercial
docks, facilities that have been designed for mooring,
government-furnished mooring facilities, or fleeting areas.
Figure C-1 - Removal of barge wrapped around dam pier - Markland Lock and Dam, Ohio River, 1967
EM 1110-2-2607
31 Jul 95
(3) Recommend installation of mooring facilities both
upstream and downstream of navigation structures for
tows awaiting lockages.
(4) Recommend each district institute training programs for lock and dam personnel to familiarize them
with decisions that need to be made in emergency
b. Coordinate efforts with other agencies and navigation interests.
(1) Recommend the Corps of Engineers establish
formal liaison and participate with the Coast Guard, other
federal agencies, and navigation industry groups in public
deliberations and studies concerning the enforcement of
safe navigation on the canalized rivers.
(2) Subjects that may be discussed by these and other
bodies which could significantly influence the Corps’
plans for protection of its navigation structures and on
which the Corps’ view should be made known include the
following: the analysis of requirements for permanent
mooring facilities between dams; the development of
more specific regulations affecting mooring procedures;
regulation of the size and power of tows to ensure safe
control of the tow’s movement under any reasonably
anticipated river conditions; Coast Guard examination and
licensing of selected personnel on towboats and self-propelled barges; and mechanical inspection of towboats by
the Coast Guard.
c. Engineering modifications. Recommend engineering and economic feasibility studies for installation of
protective barriers or lengthened guidewalls upstream of
dams, or modification of piers, to prevent major damage
to structures by runaway tows.
d. Recovery operations equipment.
(4) Recommend technical assistance from
HQUSACE and other engineer agencies, such as Engineer
Research and Development Laboratories, to determine
feasibility of utilizing explosive anchors for emergency
mooring of recovery rigging to the lock and dam structures.
(5) Recommend each district examine its capabilities
to ensure the following: capability for rigging of heavy
wire ropes and chains, and for underwater cutting of steel
by torch; development of sounding techniques to
accurately determine the underwater positions of sunken
barges and obstructions; provision of heavy anchors, and
of suitable anchor derrick and winch barge for use in
safely positioning floating plant above dam; supply of
assorted heavy slings and haul cables with suitable terminal fittings and quick-release devices; development of
grappling devices and techniques for quick attachment of
haul cables to submerged barges not accessible for conventional attachment; development of equipment and
techniques for quick introduction of compressed air into
sunken barge compartments; and provision of adequate
radio communications during recovery operations between
government, navigation, and contractor interests.
e. Modification of lock and dam structures.
(1) Recommend provision of adequate facilities on
river walls, piers, and abutments both upstream and downstream of navigation structures for positioning floating
plant and for rigging during recovery operations.
(2) Recommend design and procurement of special
lifting beams for use with overhead bulkhead cranes.
(3) Recommend engineering, economic, and feasibility studies to provide for use of versatile overhead
piggy-back cranes of 50-ton capacity and for clamshell
bucket operation and lowering of personnel to work areas.
(1) Recommend whirler-type derrick-boat of approximately 300-ton capacity be made readily available for
emergency use.
(4) Recommend engineering and economic feasibility studies for pre-installation of chain slings in gatebays to expedite removal of objects with bulkhead crane.
(2) Recommend the provision (either by lease or
procurement) of a towboat for each district or applicable
waterway of sufficient thrust and size to facilitate
handling of floating plant that would be used in a recovery operation.
(5) Recommend each district install anchor bolts on
river wall immediately upstream of the dams to facilitate
timely installation of portable winches.
(3) Recommend each district fabricate or procure
effective power-driven cutting beams to separate barges
wrapped around the dam pier structures.
(1) Recommend each district organize a marine
disaster recovery team to ensure adequate supervision of
three-shift recovery operations over an extended period.
f. Organization.
EM 1110-2-2607
31 Jul 95
(2) Recommend each district have a trained, experienced Technical Liaison Office as a single point of
contact for coordination of public information activities
during emergencies.
The positioning of the barges around the piers prevented
four of the five 84-ft tainter gates of the dam from closing, and this resulted in the eventual loss of the Maxwell
(3) Recommend each district maintain a current list of
marine contractors and contractors’ equipment available
for possible use in marine disaster recovery operations.
(2) At Locks and Dam 2 at mile 11.2 on the Monongahela River, seven barges (six coal and one tanker)
floated uncontrolled into the locks and obstructed navigation through the two lock chambers. The empty tanker
barge came to rest nearly perpendicular to the river flow
and balanced itself across the land wall just upstream of
the land chamber emergency dam. It extended some 80 ft
into the upper approach to the large lock chamber. An
empty coal barge came to rest atop the upper middle wall
and upper guard wall, completely blocking the upper
approach to the small lock chamber and virtually all of
the approach to the large lock chamber. An empty coal
barge remained buoyant on one end just upstream of the
river chamber’s emergency floodway bulkhead for a short
time after the waters receded below the top of the lock
walls. As the lock crew removed the last panel of the
floodway bulkhead after closing the downstream lock
gates, the barge surged downstream, hit the bulkhead
panel, and later sank within the small lock chamber.
Another empty coal barge sank across the upper middle
wall, obstructing both lock approaches. Two more empty
coal barges sank across the upstream end of the guard
cell. In addition, another empty coal barge impacted
against this guard cell and rested atop the two other
sunken barges.
(4) Recommend that periodic seminars be conducted
with key personnel, such as Chiefs of Branches and Construction Resident Engineers, reviewing plans and capabilities and pre-establishing key emergency team members
for recovery operations.
g. Applications. Not all the above recommendations
will be possible or practical in every Corps district with
navigation dams. The recommendations appear to be
written more specifically for the navigation dam projects
on the Ohio River. Some of the recommendations have
been implemented and some have not. It is recognized
that some of them would be difficult to design into a
project and would be very expensive.
C-8. Maxwell Incident of 1985 (Pittsburgh
a. General. On November 5, 1985, as a direct result
of storms generated by Gulf storm “Juan,” floodwaters in
the Monongahela River basin reached record levels in
many locations from Charleroi, Pennsylvania, south into
the mountains of West Virginia. As a result, as many as
120 barges that had been moored at various landings in
the navigation pool broke their moorings and began to
float downstream. As they moved in their uncontrolled
journey, some were intercepted by towboat crews, some
were beached on lowland areas, and others either sank or
ended up against highway or railroad bridges or Corps of
Engineers dam piers.
(1) At the Maxwell Locks and Dam project located at
river mile 61.2 on the Monongahela River, 20 coal
barges, both loaded and empty, either individually or in
groups of two or three, approached the dam, which had
all five of the 84-ft-wide tainter gates in the fully open
position. Two barges passed through the gate bays and
sank just downstream of the dam. The other 18 impacted
on the dam piers and stacked themselves up in positions
that required much effort and time to remove. Four
empty barges were still afloat and were retrieved by
government and contractor towboats. The remaining
14 barges either sank or became entangled against the
dam piers or rested broken atop the upper guard wall.
(3) Numerous other barges and pleasure boats were
observed going over the fixed-crest dam during the height
of the flood.
b. Causes of incident.
(1) Highest flood of record on the Monongahela
River basin.
(2) Possible inadequate mooring of some barges
which broke away and impacted other moored barges,
which then also became free-floating and uncontrolled.
c. Major impacts of incident.
(1) The blocking of navigation traffic at Lock 2 and
the loss of the Maxwell pool caused navigation traffic to
cease on the Monongahela River for some six weeks. As
a result of this traffic stoppage and its ripple effect on
dependent business interests, plus loss of the barges, tremendous economic losses were incurred.
EM 1110-2-2607
31 Jul 95
(2) Structural damage to Lock 2 and to Maxwell
and procedures for assuring their proper and continued
(3) Damage to highways and highway bridges, and
railroads and railroad bridges.
(8) Conduct research on physical and economic
feasibility of constructing a structural barrier just upstream
of each gated dam.
(4) Four municipal water companies with intakes in
the Maxwell pool were adversely affected and had to have
special help from Corps personnel in order to maintain
water services to their customers.
d. Recovery operations. The overall recovery operations to restore normal navigation traffic movement on the
river and to return all other affected interests to their fully
operational conditions were conducted November 5, 1985,
through December 16, 1985. The United States Coast
Guard, the commercial towing industry, the affected water
companies, salvage contractors, and explosive demolition
contractors joined the Corps of Engineers in this recovery
e. Summary of recommendations based on November
1985 Maxwell Incident. The following emergency action
plans were suggested by the Pittsburgh district as observations and recommendations for consideration by all Corps
organizations when preparing for or responding to similar
(1) Contingency plans should be developed by every
interest that would be affected when a pool is lost.
(2) River recording gages and staff gages should be
protected as well as possible from the effects of flooding.
Staff gages should be placed in such a way that they can
be observed at all times.
(3) Operational contingency plans covering all types
of emergencies should be prepared for all district installations, particularly navigation dams.
(4) Minutes of meetings, daily memos of organization
activities, and cataloging of slides and photos are necessary during all recovery activities for future report preparation and for use in any subsequent litigation.
(5) Maintain close contacts with the National Weather
(6) Involve affected commercial navigation interests
as soon as possible after an incident.
(7) The Corps should take the lead in helping navigation interests develop standardized mooring facilities
(9) Assure that radio contact will always exist
between locks and the District Office.
(10) Determine the availability of horizontal pulling
equipment that could be readily contracted in an
(11) Establish separate account numbers to identify
efforts expended on each vessel and the separate identifiable tasks involved in the total operation.
(12) Notify railroad and highway interests when
conditions indicate that loss of a navigation pool is imminent.
f. Report. A comprehensive report covering all
aspects of this incident can be obtained from the Pittsburgh district. The report, dated December 1986, is entitled “After Action Report - Monongahela River Barge
Breakaway Incident - November 1985.” Excerpts from
the Pittsburgh report have been used in this manual.
C-9. Maxwell Incident of 1990 (Pittsburgh
a. General.
During December 1989, Pittsburgh
district rivers and adjoining streams were frozen with
thickening ice. The United States Coast Guard issued
three notices to mariners between December 21 and 26,
1989, warning that icing conditions were continuing to
worsen along the Allegheny, Ohio, and Monongahela
Rivers with reports of ice ranging from four to eight
inches thick; that operators of fleeting areas be advised to
remain on constant alert for ice floes which might cause
barge breakaways when temperature rises occur; and that
operators double up on their mooring lines, provide for
towboat assistance, and keep a constant surveillance of
their fleeting areas to minimize barge breakaways.
(1) A combination of moderation of the weather and
heavy rains between December 29, 1989, and January 1,
1990, caused breakup of ice in the river and melting of
some snow on the watershed. This combination of events
caused flooding and movement of ice on the Monongahela River. The fast-flowing high water and breaking
ice jams knocked about 60 barges from their moorings on
EM 1110-2-2607
31 Jul 95
January 1, 1990, along the Monongahela and Ohio Rivers
and slammed the barges into bridges, locks, and dams.
Thirty-seven coal barges moored at a coal-processing
facility in the Maxwell pool broke their moorings and
began traveling downstream. Upon reaching the Maxwell
Locks and Dam, two of the barges passed through the
gate bays and sank downstream of the dam, and one
barge sank about 1 mile upstream of the dam. The
remaining 34 barges collided with the dam piers and
stacked up on one another and sank.
involved concentrated efforts by government forces,
private towing companies, marine surveyors, salvage contractors, and local affected interests.
(2) Fourteen barges were also adrift in the lower
Monongahela River below Maxwell Dam and the adjacent
Ohio River. These barges were retrieved before they
could cause any extensive damage. Some bridges on the
Monongahela and Ohio Rivers were damaged by the
runaway barges in the Maxwell pool and downstream to
(1) Require all facility operators with Waterfront
Facility Operation Guides to revise their guides to include
precautionary procedures to follow in river icing and ice
flow conditions.
b. Causes of incident.
e. Summary of recommendations based on January
1990 Maxwell Incident. The following emergency action
plans were suggested by the Pittsburgh district as observations and recommendations for consideration by all Corps
organizations when preparing for or responding to incidents similar to this one.
(2) Provide a public affairs representative immediately after an incident for media and general public contacts. Station this person in the project manager’s office
until a separate public affairs facility is established.
(1) Flooding and ice floes caused by rising temperatures, heavy rains, snow melt, and ice break-up.
(3) Equipment for salvage of sunken barges should
(2) Possible inadequate mooring of some barges,
which drifted downstream and caused other barges to
break their moorings.
(a) Two A-frames with a minimum lifting capacity
of 200 tons each.
c. Major impacts of incident.
(1) Thirty-four barges collided with the Maxwell Dam
piers and sank after piling on top of each other as
described above.
(2) One spillway gate at Maxwell Dam could not be
(b) Four derrick boats with 100 ft of boom and
lifting capacities between 50 and 150 tons.
(c) A clam shell bucket without teeth having a
capacity of 3 to 4 cu yd.
(d) Two horizontal pulling winches having a minimum pulling capacity of 100 tons each.
(e) Two towboats with a minimum of 800 hp.
(3) Tainter gates and steel sheet piling at Maxwell
Locks and Dam suffered structural damage.
(4) Dollar losses for barges and for coal on barges
were sustained.
(5) Five bridges hit by the barges were temporarily
(6) Drawdown of Maxwell pool affected water supply
facilities and navigation traffic.
d. Recovery operations. Recovery operations spanned
the period January 1, 1990, through February 19, 1990.
Restoration of all facilities to pre-incident conditions
(4) When salvage work requires a diver, it is recommended that the Corps require salvage contractors performing diving operations to have a standby diver
equipped with scuba gear tend the first diver, due to
unpredictable and dangerous conditions associated with
the diving activities.
f. Report. A comprehensive report covering all
aspects of this incident can be obtained from the Pittsburgh district. The report, dated January 1991, is entitled
“After Action Report - Monongahela Barge Breakaway
Incident - January 1990.” Excerpts from the Pittsburgh
report have been used in this manual.
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