Stream Restoration in an Urban Park Setting

摘要

Miller's Run through Bruce Henry Park, a multi-use township park, was bordered by an unstable makeshift levee that created unsafe conditions and isolated the stream from the park. The levee was constructed partially from concrete rubble and road maintenance waste. The aquatic habitat in Miller's Run was very limited. Wide shallow reaches of stream had very little flow variability and poor cover. To improve the aquatic habitat, remove the unstable levee, improve floodplain storage, and enhance access to the stream, the owner, Loyalsock Township, secured a Growing Greener Grant through the Pennsylvania Department of Environmental Protection to restore 260 meters of Miller's Run. The stream channel and adjacent floodplain were designed using natural channel restoration techniques. Use of this method of stream channel design, based on the science of fluvial geomorphology, allows the stream channel to be constructed in a manner that mimics the form the stream would take in an undisturbed setting. The geometry is developed to transport sediment and maintain its form. Pools and riffles are designed to provided natural stream function and enhance habitat. Large rock structures are employed to maintain pools and align high velocity streamflow away from the streambanks. Tree, shrub, and herbaceous plant species native to Pennsylvania's floodplains are used to stabilize the streambanks and provide wildlife habitat in the adjacent floodplain. A number of urban design constraints presented challenges during design and construction of this project. Numerous drainage pipes outlet to the stream channel within the park. A sanitary sewer line parallels Miller's Run. Protecting the sanitary sewer line and stabilizing the drainage pipes at their point of entry were critical project objectives. Through the use of large rock structures designed to modify the channel hydraulics and reduce the near bank velocity all pipe discharges were protected. This reach of Miller's Run is now one of the few areas on the stream that is accessible for recreational use. Bank erosion is significantly reduced while instream aquatic habitat and aesthetic value of the stream is enhanced. A streamside trail system and extensive landscaping enhance the stream restoration converting an eyesore to a recreational resource.