Peters Creek Natural Channel Design Jefferson Hills Borough, Allegheny County Municipal/Inspection Team September 2005 Gateway Engineers was asked to stabilize the stream banks to protect a sewer crossing in Jefferson Hills Borough. The banks had eroded, exposing the sewer to objects in the flow, ultimately breaking the sewer. Typical bank stabilization methods such as gabion baskets, grouted rip-rap or retaining walls are unsightly and often only treat the symptoms without providing a cure for the actual problem. In many instances these types of hard armor solutions may correct the problem for a short period of time in one location while creating new problems in other areas. Peters Creek is a valued asset to the Borough. The stream provides beautiful scenery and is adjacent to a nature trail which is heavily used by area residents. A local anglers group provides fish used to stock the stream. The Borough asked that the proposed repair not only protect the sewer permanently, but fit into the surrounding habitat. To solve the problem, Gateway used natural stream bank stabilization techniques such as channel shaping, in-stream rock structures, rock vanes, boulder bank, rock toe protection and riparian buffer zones. In-stream structures direct the energy of the stream into newly created scour holes in the center of the channel, where it can dissipate naturally without damaging the banks. In-stream structures were placed upstream of the area being protected to control the direction of the flow before it gets to the sewer. Traditional hard armor, such as grouted rip-rap, would usually be placed at the sewer, so it must be designed to take impacts from debris in the stream. Traditional hard armor methods eventually fail over time for this reason. In addition to protecting the sewer, the rock structures improved fish habitat and water quality. The natural rock used for this project came from a local developer, saving the Borough thousands of dollars.