2018 Pollutant Reduction Plan
A Municipal Separate Storm Sewer System, otherwise known as an MS4, is a collection and conveyance system designed to move stormwater (including rainwater and snow melt) away from public infrastructure and into local waterways. The system is comprised of inlets, pipes, swales, open channels, and other components. The MS4 is a key piece of public infrastructure.
Since stormwater can become contaminated during overland flow, pollutants are likely to end up in local waterways when picked up by stormwater. These pollutants could include pesticides, fertilizers, sediment, oil, and grease among others that could threaten the quality of our local waterways. The negative impacts from this could include harm to freshwater ecosystems, degradation to the aesthetic value of waterways, and contamination of drinking water.
The MS4 Program is intended to improve the quality of waters by reducing the discharge of pollutants to the maximum extent possible to meet water quality standards and satisfy the water quality requirements of the federal Clean Water Act and the Pennsylvania Clean Streams Law. Federal regulations require the development and implementation of a Pollutant Reduction Plan for discharges into the three watersheds in Willistown -- the Crum Creek, Ridley Creek, and Valley Creek watersheds.
The Township’s draft Pollutant Reduction Plan (PRP) is required by the National Pollutant Discharge Elimination System (NPDES) Individual Permit for Stormwater Discharges from Small Municipal Separate Storm Sewer Systems (MS4). The PRP estimates the pollutant loads generated by existing land cover within the Township and provides a 5-year plan to reduce these loads as the permit requires. The PRP includes detailed maps of the planning area, existing pollutant load calculations, proposed Best Management Practices (BMP) to achieve the required load reductions, cost estimates and long-term operation and maintenance procedures.
The draft PRP can be viewed, downloaded, and printed by clicking on the links below. The draft PRP is also available for review in the Township offices located at 688 Sugartown Road, Malvern, PA 19355.
MS4 Application and Checklist
MS4 Public Report
Appendix A Annual Due Date & PADEP Permit Letter
Appendix B 2017 Willistown Urbanized Area Outfall Map
Appendix C (Map 1) Urbanized Area Outfall Map
Appendix C (Map 2) Aerial Outfall Map
Appendix D Willistown MS4 Requirements Table 08-10-17
Appendix E PRP Simplified Method Narrative & Instructions
Appendix F (1) Ridley Creek WikiWatershed Calculations Table 1a
Appendix F (2) Crum Creek WikiWatershed Calculations Table 1a
Appendix F (3) Little Valley Creek WikiWatershed Calcs Table 1a
Appendix G Ridley Crum Little Valley Creeks Load Rate Calculations
Appendix H Existing Loading WO Accounting for BMP's
Appendix I Complete Sediment Removal Tabulations
Appendix J Example Details
Appendix K Considerations of Stream Restoration Projects