What is the Pollution Reduction Plan (PRP)?
In Pennsylvania, Small Municpal Separate Storm Sewer Systems (MS4) must apply for National Pollutant Discharge Elimination System (NPDES) Permit Coverage (PAG 13) if they are located in an Urbanized Area. Upper Allen Township is located completely within an urbanized area, and also completely lies within the Chesapeake Bay Watershed. The 2018 NPDES Permit requires that any regulated MS4 that discharge surface waters impaired for certain pollutants and/or that discharge to waters in the Chesapeake Bay Watershed are required to develop a Pollutant Reduction Plan (PRP).
The purpose of our PRP is to satisfy the 2018 NPDES Permit requirements, ultimately with the goal of reducing the three specific pollutants (sediment, phosphorus, and nitrogen) from being discharged to the local receiving waters. Our Townships plan will focus on the impaired local surface waters first, and then it will be determined if the Best Management Practices (BMPs) proposed in those storm sewersheds will be be sufficient to meet the overall pollutant reduction requirements.
The PRP is an unfunded Environmental Protection Agency (EPA) mandate.
2021 PRP Projects
The Canterbury Estates stormwater basin
This project was designed to standards that have become outdated compared to modern Act 167 and the Department of Environmental Protection model stormwater ordinances. The Canterbury Estates Water Quality Basin project involves the modification of the existing detention basin outlet structure to improve the facility’s ability to reduce the peak rate of stormwater runoff downstream, increase the stormwater retention volume, and inclusion of water quality enhancement features. A significant amount of stormwater runoff currently bypasses the stormwater facility and creates flooding conditions downstream. A secondary earthen berm was constructed downstream of the existing detention basin to manage stormwater runoff from an expanded drainage area. The secondary facility will reduce the total sediment, nitrogen, and phosphorus pollutant loads currently being discharged downstream.
2022 PRP Projects
McCormick Park bank regrading and stabilization
This project required a General Permit for Bank Rehabilitation (GP-3) and will be graded from the overbank and stabilized with erosion matting and native vegetation. This will lower stream bank slopes, and provide erosion control to protect stream banks from excess erosion that causes sedimentation down stream. Proposed plantings or live staking would be utilized to encourage further stabilization and habitat creation. Additional coordination with DEP outside of the scope of this study is recommended to confirm that this minor bank work would be applicable towards the load reduction requirements of the township’s PRP prior to moving forward.
This stream restoration is set to begin in early April of 2022, and will prevent approximately 8,976 pounds per year of sediment from being transported downstream.
The Spring Run stream restoration project
This project will establish floodplain benches, Encourages the creation of wetlands and habitat, and will serve as an aesthetic enhancement of the waterway. 659 linear feet of actively eroding banks will be restored to significantly reduce the pollutant load being transported downstream (see cross-section below). Excess sediment deposited in the historic floodplain areas will be removed to re-establish floodplain benches. The floodplain benches will serve to reduce stormwater flow velocities and shear stresses during high flow events and allow for native vegetation to be reestablished.
This stream restoration is set to begin in early April of 2022, and will prevent approximately 30,294 pounds per year of sediment from being transported downstream.