The Bells Mill tributary to the Wissahickon Creek has suffered severe erosion to its streambanks, which has resulted in massive amounts of sediment entering these streams. Eroded sections of the streambank along Bells Mill Road have caused electric power lines to slump into the creek, presenting a safety hazard.
The two major stormwater outfalls that discharge into Bells Mill Creek have created these degraded stream conditions. Runoff flowing from these outfalls has severely eroded the stream’s channel, causing it to become entrenched and overwidened. A scour pool exists where one outfall discharges into the tributary, creating stagnant water at low flows. The entire length of the tributary downstream of the outfalls is actively eroding due to high flows during wet weather.
As part of the stream restoration, GTS Technologies will regrade the streambank and install structures and large woody debris in the creek. This project uses standard rock vanes, wing deflectors, and root wads placed along the base of the streambank to stabilize the bank from erosion. The structures will also protect sewer infrastructure that run alongside the stream. After these structures have been installed, the streambanks will be graded to their natural slope.
Construction on this project is scheduled to begin in June 2010 and will be completed by the end of the year.
Watershed: Wissahickon Creek
Total: $2.25 million ($250,000 for design, $2 million for construction)
Philadelphia Water Department
1101 Market Street, 4th Floor
Philadelphia PA 19107