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Constructed
wetlands are artificially created, lined ponds with a
coarse media, such as gravel, to support aquatic vegetation.
The vegetation aids in the reduction of nutrient pollutants,
such as nitrogen and phosphorus, and helps to remove solid
particles by trapping them in the plant root structures or
gravel. All wetlands require some harvesting of the plants
(which should be performed just before the onset of summer)
and periodic removal of solids from the gravel.
Constructed
wetlands can be one of two types: 1) free water surface
(FWS) or 2) subsurface flow. FWS wetlands are designed
to be more attractive to aquatic life since they function
very similarly to natural ponds. The water level in subsurface
flow wetlands is kept below a gravel base. This is advantageous
because the possibility that people will come in contact with
the effluent is reduced.
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