Municipal Separate Storm Sewer System Program
MS4 is an acronym for a Municipal Separate Storm Sewer System. It's a system of stormwater conveyances and structures owned or operated by a public agency that does not connect to the sanitary sewer system and does not lead to a wastewater treatment plant. It discharges untreated water into local drainageways, streams, and rivers.
Pennsylvania's MS4 program is implemented by the Pennsylvania Department of Environmental Protection (DEP), which fulfills this role to comply with federal mandates under the Clean Water Act. The Environmental Protection Agency (EPA) has an oversight role because they are the federal agency charged with managing the Clean Water Act.
National Pollutant Discharge Elimination System Permit
The authorization that MS4 communities get from the DEP to legally discharge stormwater into local streams and rivers is called an "NPDES" permit which stands for National Pollutant Discharge Elimination System. To meet the terms of their NPDES Permit, communities need to develop what's called a "Stormwater Management Program" (SWMP). Communities that discharge stormwater into the Chesapeake Bay Watershed, such as Lower Paxton Township, are also required to develop a "Pollutant Reduction Plan" (PRP).
There are 6 Minimum Control Measures (MCM) that make up Lower Paxton Township's Municipal Separate Stormwater System (MS4) program. These 6 MCMs are:
- Construction site runoff management
- Good housekeeping and pollution prevention for municipal operations
- Illicit discharge and detection
- Post-construction stormwater management
- Public education
- Public Education includes distributing informational posters, meeting with the public, providing links on the web page to related information, and providing a means for reporting suspected pollution concerns.
- Public involvement
- Construction Site Runoff Management
- Good Housekeeping & Pollution Prevention for Municipal Operations
- Illicit Discharge & Detection
- Post-Construction Storm Water Management
- Public Involvement
Construction activities have sediment runoff rates 1,000 to 2,000 times greater than forested land and 10 to 20 times greater than agricultural lands. The Dauphin County Conservation District has the primary responsibility for managing construction runoff.
Lower Paxton Township works closely with the Conservation District to mitigate construction runoff through regulations to control construction activities and penalties for non-compliance; review of construction plans to ensure site-specific needs are addressed, and site inspections to ensure necessary control measures have been installed and maintained.
The Township must examine its actions to ensure that it is not contributing to water degradation. The Township works to accomplish this objective through:
- Training employees to eliminate pollutants from entering the storm system.
- Modifying and constructing facilities to reduce runoff and possible contamination.
An example of good housekeeping is Township salt domes, which shelter stockpiled salt from precipitation, eliminating dissolved salts from entering the storm sewer system.
Any discharge to an MS4 that is not composed entirely of stormwater, with some exceptions, such as hydrant flushing and firefighting runoff, is an illicit discharge. MS4 facilities are not designed to convey or handle illicit discharges.
Illicit discharges enter the MS4 system either through direct connections or indirect connections, such as leaking sanitary sewer systems, spills that reach storm drains, or deliberate dumping into drains or other facilities. Illicit discharges can contribute to high levels of pollutants including oils, heavy metals, excess nutrients, and viruses/bacteria.
Proper site management reduces the effects of development on our waterways. Development can cause waterway degradation by increasing sediment load, possible chemical or nutrient contamination, reducing ground water recharge, and increasing the volume and speed of water flows.
Township ordinances govern the design, construction, and maintenance of storm water facilities, and provide penalties for non-compliance. The Township also inspects existing facilities to ensure they are working properly, working with property owners to ensure compliance.
Citizens are encouraged to comment on stormwater issues, to organize groups to stencil storm drains to increase public awareness of the hazards of water pollution and to promote community clean-ups and adoption of local waterways.