Penn Alexander School Stormwater Management Techniques


The Penn Alexander School, located at 43rd Street and Locust Street in West Philadelphia, sought to mitigate storm runoff from buildings being constructed onsite by implementing stormwater best management practices. Cahill Associates designed three systems – rain gardens, a porous pavement playground with a subsurface infiltration bed, and an underground infiltration area connected to roof leaders to manage rooftop runoff – to control the entire site’s stormwater runoff.

This project keeps stormwater runoff on the site, which reduces the volume of runoff delivered to the city’s combined sewer system. This practice prevents the sewer system from overflowing and discharging sewage into the Delaware River. This project was completed by the summer of 2001 and serves as a demonstration site and provides educational opportunities.


County: Philadelphia
Watershed: Schuylkill River


Cahill Associates
PA Department of Environmental Protection
Philadelphia Water Department




Daniel Wible, PE
Cahill Associates
104 S. High Street
West Chester, PA 19382

Site Plan

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