A common stormwater treatment system is called a wet detention pond. Wet detention ponds contain water at all times and serve a dual purpose. They treat stormwater runoff to protect our creeks and streams, and during severe storms, they help prevent flooding.
Detention ponds temporarily store stormwater runoff, thereby reducing the peak rate of runoff to a stream or storm sewer. ... Detention ponds are basins that receive and hold runoff for release at a predetermined rate, thereby reducing the peak runoff delivered to storm sewers and streams.
A typical extended detention basin will range from 3 to 12 feet in depth. Depth is often limited by groundwater conditions or the need for positive drainage from excavated basins.