MIL-HDBK-1164
(1) D= Daily; W = Weekly; M= Monthly; Q = Quarterly;
A = Annually, as conditions may indicate.
(2) The frequencies shown are suggested frequencies that may be modified by local command, as
individual installation conditions warrant.
4.6.1
Dams and Spillways
4.6.1.1
Concrete and Masonry Dams. Inspect dams periodically. At each
inspection, lubricate gates and appurtenance equipment as necessary. Leaks or
seepage indicate cracks that can be repaired with cement mortar or grout. Seal the
upstream side first so that water is not trapped in the dam.
In winter, break the ice several feet upstream to protect the dam against
ice thrust.
4.6.1.2
Earth and Rockfill Dams. Properly constructed earth dams keep water
from entering the earth beneath or around the sides of the dam. They also allow any
water that is not retained behind the dam to travel to the downstream face of the dam
without building up internal pressure. Inspect earthfill and rockfill dams and maintain a
proper appearance with all slopes sodded or graveled. Keep riprap on the upstream
face even and in good condition.
If leaks or seepage are evident from inspection, the turbidity of the
seeping water indicates the importance of the condition. Clear water indicates no loss
of soil and no increase in the size of the leak. Turbid water indicates a worsening of
conditions: the more turbid the water, the more urgent the need for repair. Seepage at
or under the toe of the dam indicates a dangerous condition. Such seepage can result
in dam failure. If seepage is observed, report this to a higher authority at once.
Repair minor leaks immediately by excavating or drilling to a moderate
depth on the upstream face and sealing with puddled clay rammed into place. In the
case of serious leaks, cut down the damn from the tip and fill with good material. It is
recommended that new fill be bonded into the original material and compacted. When
seepage is detected at the toe of the dam, add new layers of earth to the downstream
face.
4.6.1.3
Spillways. Keep spillways free of trash and debris, since blocked
spillways may cause overtopping of the dam and possible failure by erosion. Earthfill
dams invariably fail if they are overtopped. A log boom stretched across the reservoir
about 30 feet ahead of the spillway helps keep it clear. Spillway flashboards are not
used if the dam is subject to flash flooding.
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