CEMP-ET
TI 804-01
1 July 1908
e. Detention Ponds, Retention Ponds, and Infiltration Basins. Detention ponds, retention
ponds, and infiltration basins are drainage devices used to control the rate of runoff from the
increased impervious surfaces resulting from construction. The increase in runoff is held
within these ponds and slowly released at rates that are equal to or less than the rates that
occurred before construction. The maintenance of pre-construction runoff rates helps prevent
flooding, erosion and sedimentation of recipient drainage ways. Ponds and basins can be
designed to allow collected runoff to stand long enough for heavier sediments to settle to the
bottom, thereby reducing sedimentation downstream.
(1) Detention ponds release all of the collected water at a specific rate. Detention
and retention ponds are especially useful during construction when the lack of drainage
systems and vegetative cover make it difficult to control Storm water flow and erosion.
(2) Retention ponds function the same as a detentions ponds except they are
designed to retain a certain level of water permanently and release all of the collected water
above the permanent level at a specific rate.
(3) Infiltration basins retain all of the collected water until it infiltrates or evaporates.
Infiltration basins are important for increasing groundwater recharge, especially in highly
urbanized areas. Typically, infiltration basins are wide and shallow to facilitate rapid infiltration
and evaporation. Basin floors are graded at 0 percent or close to 0 percent and have a
permeable base. Infiltration basins are designed to be dry when not in use and can serve
other functions as well, such as athletic playing fields.
(4) Local, state and federal jurisdictions are more frequently requiring the use of
detention/retention and infiltration ponds a means of maintaining water quality. Requirements
for designing detention ponds, retention ponds, and infiltration basins should be verified by
local and state agencies.
(5) These ponds and basins should be designed to serve other functions in a
development such as a water feature, wildlife habitat, wetland, and wastewater reclamation.
f. Erosion Control. Erosion control evaluation and implementation begins with identifying
the causes of erosion and then implementing controls to limit erosion.
(1) Erosion occurs as the result of:
(a) Lack of vegetative cover.
(b) Excessively steep slopes.
(c) Excessive runoff.
(d) Unstable soils.
(e) A combination of the above.
(2) Erosion control can be improved by:
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