MS4 (Municipal Separate Storm Sewer System)

What is stormwater and why can it be a problem? 

Stormwater is water from precipitation that flows across the ground and pavement when it rains or there is snow or ice melt.  In Blawnox Borough our stormwater travels down through the borough along the streets or by pipes that drain into the Allegheny River. Stormwater becomes a problem when it picks up debris, chemicals, dirt, and other pollutants as it flows, which are then released into the river. Stormwater can also cause flooding and the erosion of stream banks. 

What are some common stormwater pollutants?

  • Sediment
  • Nutrients
  • Bacteria
  • Trash and Debris
  • Toxic Chemicals
  • Chlorides
  • Trace Metals
  • Oil and Grease

What are some causes of these common pollutants?

  • Sediment - Erosion from construction, landscaping, stream bank erosion, building and grounds maintenance.
  • Nutrients - Pet droppings, urban housekeeping, landscaping (fertilizer) and non stormwater connections to storm drains.
  • Bacteria - Pet and other animal droppings and non stormwater connections to storm drains. 
  • Trash and Debris - Litter, urban housekeeping, grounds maintenance and road maintenance.
  • Toxic Chemicals - Automotive maintenance (antifreeze), urban housekeeping (cleaners),  landscaping (pesticides), buildings and grounds maintenance (cleaners, solvents, paints), spills and illegal dumping. 
  • Chlorides - Winter road and sidewalk maintenance. 
  • Trace Metals - Automotive traffic, automotive maintenance and road maintenance. 
  • Oil and Grease - Automotive maintenance, urban housekeeping, construction, spills and illegal dumping. 

Stormwater and the Borough of Blawnox

The Pennsylvania Department of Environmental Protection (DEP) has a state permitting program for stormwater. The DEP gives permits to Municipal Separate Storm Sewer Systems (MS4s), which are a conveyance or a system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) that are owned or operated by a public entity, are designed or used for collecting or conveying stormwater, and are not a combined sewer or part of a publicly-owned treatment works. All owners and operators of MS4 permits are required to satisfy the requirements of the general permit. This means that the operator or owner is required to develop and implement a Stormwater Management Plan (SWMP). The SWMP is comprised of six (6) mandatory Minimum Control Measures (MCMs):

  1. Public Education and Outreach
  2. Public Participation/ Involvement
  3. Illicit Discharge Detection and Elimination
  4. Construction Site Runoff Control
  5. Post-Construction Runoff Control
  6. Pollution Prevention/ Good Housekeeping

Staff Contacts

Name Title
Mallori McDowell MS4 Coordinator