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Stormwater Basin

A stormwater basin is a vegetated depression designed to store, infiltrate and/or slow stormwater runoff that would otherwise cause flooding and erosion. A retention basin, or wet pond, is designed to collect and store runoff as a permanent pool of water that removes pollutants through settling and biological uptake. A detention basin collects runoff and slows the flow before releasing it into a smaller outlet. An infiltration basin operates much like a detention basin, except it is designed to infiltrate the runoff into permeable soil. While basins have traditionally been large, mowed systems with concrete channels, newer designs incorporate native vegetation that allows for greater filtration and improvement of water quality.  

Stormwater Basin at Cliveden Park

The stormwater demonstration project at Cliveden Park captures runoff from adjacent streets and uses the park’s natural topography to detain stormwater before it flows into the combined sewer system. Small upland depressions provide water quality treatment and infiltration of stormwater, and a modified outlet structure allows water to pond in the existing wetland before it is slowly released. The system will provide stormwater volume removal through evapotranspiration and infiltration, and will reduce the flow rate to the combined sewer system during the small, frequent storms that cause the majority of combined sewer overflows. The system meets stormwater management objectives, enhances the existing wetland in the park, and is also provides an amenity for the park community.



Chew Ave and Johnson Ave, Philadelphia, PA

Mt. Airy

Google Map of 39.939472,-75.15823

Lead Agency

Philadelphia Water Department


Pennsylvania Horticultural Society
PA Department of Environmental Protection
Philadelphia Department of Recreation
Friends of Cliveden Park
Bank of America