The Philadelphia Water Department (PWD) developed a 25-year program to combat combined sewer overflows (CSO) and protect and enhance the health of their waterways through investments in green stormwater infrastructure called Green City, Clean Waters. This program is the largest such program ever envisioned in this country and is broken into three fronts: water, land, and infrastructure.
For the water aspects of the program, our team develops restoration and stabilization designs for tributaries and main stem streams. For Tacony Creek, we improved 3.2 miles of streamline and surrounding wetlands.
We are also involved in three land-based programs: Green Streets, Green Schools, and Green Parks. A variety of practices, such as stormwater bumpouts, rain gardens, infiltration basins, tree trenches, porous pavement, and swales, are used to provide pollutant filtration while reducing the volume of stormwater discharges to the public sewer network. So far, we have greened four parks, many streets, and one school. Traditional infrastructure is sometimes more appropriate. In these cases, our team provides assessment and design of water and sewer upgrades and replacement projects.
The key to the program is a block-by-block approach in which each project is essentially treated like a pilot, monitored and tested at every turn to determine how it’s working.