The lists given here are by no means comprehensive, but should provide the reader with a guide to the various BMP types listed in the questionnaire. Extended detention ponds Depressed basins that temporarily store a portion of stormwater runoff following a storm event. May be berm-encased area, excavated pond or tank.
Water is controlled by means of a hydraulic control structure to restrict outlet discharge.
Wet ponds Similar to the extended detention pond except that a permanent volume of water is incorporated into the design. Soluble pollutant removal is enhanced by biological processes. Wet ponds can have aesthetic and recreational value, as well as offering flood-control benefits. An excavated trench lined with a filter fabric and backfilled with stone to form an underground basin. Runoff is diverted to the trench and either exfiltrates into the soil, or enters a perforated pipe underdrain and is routed to an outflow facility.