EP 1110-2-13
28 Jun 96
Appendix C
and under all operating conditions.
Visual
observations and the interpretation of instrumentation
Design
data provide the primary means for engineers to
evaluate dam safety. Recently, technology of devices
for measuring seepage, stresses and movements and
C-1. Introduction
pore water pressures in dams has improved
significantly with respect to accuracy, reliability and
Dams are unique because the design function can
economics. The planning, design, and layout of an
never be considered finished as long as the dam
instrumentation program is an integral part of the
remains in place. Because of the many unknowns
project design. Guidance on the selection and use of
usually encountered, construction (and operation)
various types of instrumentation for earth and rockfill
must be a continuation of design. Foundation and
dams is given in EM 1110-2-2300 and EM 1110-2-
borrow work during construction provide far better
1908. Guidance on the instrumentation for concrete
exploration than is available during design, and
dams is given in EM 1110-2-1908 and EM 1110-2-
changes which impact safety are common. Design
4300 (see also Lindsey et al. 1986, Keeter et al. 1986,
personnel should visit the site during construction to
Currier and Fenn 1986, O'Neil 1989). Additional
confirm that site conditions conform to those assumed
information on instrumentation of dams is available
in design or to determine if design changes are
(United States Committee on Large Dams 1984 and
required to suit the actual conditions. Operational
1986, Colorado Division of Disaster Emergency
design inspections should continue throughout the
Services 1987, Federal Energy Regulatory
life of the project. The design function includes
Commission 1991, Carpenter et al. 1988).
planning dam instrumentation to be installed during
construction and/or operation to monitor conditions
b. Types of instrumentation.
The type,
that could potentially threaten the safety of the dam
number, and location of required instrumentation
(Federal Emergency Management Agency 1979).
depend on the complexity of the project. For earth
The general design and construction of earth and rock
and rockfill dams, the types of measurements
fill dams are discussed in EM 1110-2-2300 and
generally include the following (EM 1110-2-2300
EM 1110-2-1911. The design of gravity dams is
and EM 1110-2-1908):
given in EM 1110-2-2200.
(1) Piezometers (open tube, such as the
Casagrande type, electrical, vibrating wire, or
C-2. Design Review
occasionally closed systems; located in the
foundation, abutment, and/or embankment).
All designs accomplished by an Engineering District
will be reviewed by an independent, multi-discipline
(2)
Surface monuments.
team. About 80 percent of Corps dam designs are
accomplished internally and about 20 percent are
(3)
Settlement plates within the embankment.
accomplished externally by contract with private
engineering firms (Federal Emergency Management
(4)
Inclinometers (slope indicators).
Agency 1992b; U.S. Army Corps of Engineers,
Office of the Chief of Engineers 1977).
(5) Movement indicators (at conduit joints,
outlet works, and intake tower).
C-3. Instrumentation Plan
(6) Internal vertical and horizontal movement
and strain indicators.
a. General. All Corps of Engineers dams are
required to have an adequate level of instrumentation
(7)
Earth pressure cells.
to enable the designers to monitor and evaluate the
safety of the structure during the construction period
C-1
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