Green Stormwater Infrastructure for CSO Control

Adopted in June 2011, Philadelphia Water Department’s (PWD) Green City, Clean Waters initiative seeks to establish a long-term plan for the control of combined sewer overflows (CSOs) through investments in green stormwater infrastructure (GSI), combined with traditional sewer infrastructure, and expanded treatment plant capacity. Green City, Clean Waters is a 25-year plan proposing to create natural landscapes to absorb stormwater runoff from impervious surfaces. Over the past seven years, PWD has implemented a variety of GSI systems within the combined sewer area of Philadelphia. These systems have been designed to manage more than 31 million gallons of stormwater runoff from each one-inch storm event, effectively diverting over 1.3 billion gallons of polluted water from entering Philadelphia’s waterways. For maximum impact, GSI is being implemented on a block-by-block scale to take full advantage of the economic, social, and environmental benefits associated with introducing green space into a highly urbanized environment.