UFC 3-210-10
25 October 2004
pretreated with other devices such as grit chambers, water quality inlets, sediment
8-8.2
Cost Data. Construction costs include clearing, excavation, placement of the
filter fabric and stone, installation of the monitoring well and, where desired,
establishment of a vegetated buffer strip. The 1993 construction cost for a large
infiltration trench (1.8 m (6 ft) deep, 1.2 m (4 ft) wide, and with a 68 m3 (2,400 ft3)
volume) ranges from ,000 to ,000. A smaller trench (0.9 m (3 ft) deep, 1.2 m (4 ft)
wide, and with a 34 m3 (1,200 ft3) volume) is estimated to cost from ,000 to ,500.
8-8.3
Maintenance Issues. The principal maintenance objective is to prevent
clogging, which may lead to trench failure. Infiltration trenches should be inspected
after large storm events and any accumulated debris or material should be removed. A
thorough annual inspection should include monitoring of the observation well to confirm
that the trench is draining properly. Trenches with filter fabric should be inspected for
sediment deposits by removing a small section of the top layer and examining the
material in the trench itself. When vegetated buffer strips are used, they should be
mowed regularly and inspected for erosion or other damage after each major storm
event.
8-8.4
Corrective Actions. The corrective action for infiltration trench failure is to
remove the stone and sediment that has clogged the system. The trench should be
over excavated and scarified to ensure that the infiltration capacity of the soil is
sufficient. The stone is washed to remove any sediment and then replaced. It is critical
that any surrounding areas be stabilized to eliminate the potential for sediment clogging.
8-9
INLET DEVICES (a.k.a. hydrodynamic separators). Inlet devices are flow-
through structures with a settling or separation unit to remove sediments and other
stormwater pollutants.
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SEWRPC, 1991; Harrington, 1989.
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