|A rain garden is a garden designed to collect runoff from impervious surfaces such as roofs, walkways, and parking lots, allowing water to infiltrate the ground. The garden is normally moderately depressed (lower than the surrounding ground level), with the bottom layer filled with stone so runoff can collect and pond within it. The site is graded appropriately to cause stormwater to flow into the rain garden area from the nearby impervious area. The water ponds on the surface, is used by the vegetation in evapotranspiration, and infiltrates into the subsurface stone storage and soil. Rain gardens can be connected to sewer systems through an overflow structure, but usually they are sized to infiltrate the collected stormwater runoff within 72 hours. Flexible and easy to incorporate into landscaped areas, rain gardens are suitable for many types and sizes of development and retrofits. Rain gardens are effective at removing pollutants and reducing stormwater runoff volume.|
Rain Garden at Liberty Lands
Office of Watersheds funded the development of a master plan for Liberty Lands in Northern Liberties that provides stormwater management while addressing community objectives for the park. The first phase of implementation was a performance stage backed by a vegetated stormwater management area that manages runoff from the park and an adjacent street.
Philadelphia Water Department
Pennsylvania Horticultural Society
Pennsylvania Department of Environmental Protection