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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.
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