Derry Township Municipal Authority restored 1,800 linear feet of stream bank to help the township meets its MS4 Pollution Reduction Plan requirements. The project will reduce sediment loads by more than 200,000 pounds per year (accomplishing about 20% of Derry the township’s total sediment reduction requirement and nearly all of Hummelstown Borough’s total sediment reduction requirement with just one construction project). It will also mitigate future flood risk by reconnecting the stream to the floodplain.

The existing stream bank was heavily incised. HRG regraded the bank and stabilized the channel. We determined that the channel experienced a range of shear stresses in different sections, so we recommended different bank methods and riprap toe protection in these zones to maximize effectiveness while controlling costs.

The project is located adjacent to the Jonathan Eshenour Memorial Trail, so HRG took special care in the design to minimize impacts to the trail during construction.