Stream Bank Improvement, New Freedom Borough, PA

The steep banks of the South Branch Codorus Creek (SBCC) were encroaching along the fence line and threatening additional infrastructure at the New Freedom Wastewater Treatment Plant as a result of several consecutive severe flooding events. Maintenance along the top of the bank was difficult, and the bank threatened the structural security at the plant.

The stream was rerouted around the plant during its original construction, and the stream channel migrated to realign with a more meandering pattern and to reconnect with the floodplain. In some areas, the eroded banks were 8 feet high. This section of the SBCC is listed as a wild trout reproduction stream. BH worked with the Borough and the PADEP to develop a long-term environmentally sound solution.

The design incorporated imbricated riprap with soil medium placed within voids and branch packing at the top of the bank and along the base of the imbricated riprap wall. This allowed for vegetation to establish creating fish habitat and shade to lower the temperature in the stream during the growing season. The root structures of the vegetation provided additional stabilization for the soil to prevent scouring and erosion along the top of bank and edge of stream. Furthermore, fish habitat structures were incorporated to mitigate impacts to the stream and provide critical habitat in a section of stream where previous habitat was lacking.

Through evaluation, it was determined the far side of the stream was stable enough to handle energy diverted from the wall and fish habitat structures. Years later, the Living Wall is providing critical shade and habitat and holding up to high water events without blocking flow. This technique has been incorporated into the toolbox for stabilizing highly degraded banks where natural stream design methods and floodplain reconnection is not practical.