By Jennifer Lachmayr
EPA promulgated its Phase II Stormwater regulations in an effort to reduce water pollution from a leading source, urban stormwater runoff. Phase II covers municipal separate storm sewer systems (MS4s) serving a population of at least 10,000 and having a population density of at least 1,000 people per square mile and construction sites disturbing 1 to 5 acres. The EPA will base populations on the 2000 census.
The Phase II Regulations aim to reduce the discharge of pollutants to the "maximum extent practicable;" to protect water quality; and to satisfy the appropriate water quality requirements of the Clean Water Act.
In 1993 the EPA implemented Phase I of the National Discharge Elimination System (NPDES) Storm Water Program. Phase I covers municipal separate storm sewer systems (MS4s) generally serving populations of 100,000 or greater, construction sites over 5 acres, and 10 categories of industrial activities. The Phase II Storm Water Regulations, published on December 8, 1999, cover MS4s not already covered under Phase I.
EPA defines "municipal separate storm sewer" as a "conveyance or system of conveyances, including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains owned or operated by a state, city, town, borough, county, parish, district, association, or other public body..."
This means that within a single area covered under Phase II several owners may be involved, including local sewer districts, federal and state departments, universities, hospitals, military bases, and prisons. The EPA will encourage the different owners to work together to implement a common storm water program.
Phase II may cover any other MS4s that, in the opinion of the regulatory agency, significantly contribute to water pollution. The criteria for adding an MS4 that does not meet the population requirements are:
- Discharge to sensitive waters.
- Area with high population density, high growth or growth potential.
- Border an urban area.
- Significant contributor to water pollution; or ineffective protection of water quality by other programs.
The NPDES permitting authority for each state must issue a General Permit within three years from the date of publication of the final regulations (by December 8, 2002). The owner of a designated MS4 will be required to submit for permit coverage within 90 days of issuance of the General Permit (by March 10, 2003).
The MS4 owner can either submit a Notice of Intent (NOI) for coverage under the General Permit for their state or they can submit an application for an individual permit. The MS4 owners will be required to fully implement their stormwater management programs by the end of the first permit term, which is expected to be a five-year period (March 2008).
The Phase II regulations require the owners of MS4s to implement the following six minimum control measures (MCM) :
- Public Involvement/Participation.
- Illicit Discharge Detection and Elimination.
- Construction Site Runoff Control.
- Post-Construction Runoff Control.
- Pollution Prevention/Good Housekeeping for Municipal Operations.
Of the six MCM, the one with the longest lead-time for system owners is illicit discharge detection and elimination. Federal regulations define an illicit discharge as "...any discharge to an MS4 that is not entirely of storm water..." Sources of illicit discharges include: sanitary wastewater, effluent from septic systems, commercial wastewater, spills from roadway accidents, and improper disposal of auto and household toxins, including waste oil and antifreeze.
These discharges are considered illicit because the storm sewer system will discharge these pollutants to a surface water body without treatment. Storm water runoff may contain high levels of pollutants, including heavy metals, toxins, oil and grease, solvents, excessive nutrients, viruses, and bacteria. When these pollutants are discharged untreated to water bodies, recreational use of the water body is reduced, drinking water supplies may be contaminated, and wildlife habitats are degraded.
An illicit discharge may enter a storm sewer system through direct connections with wastewater piping, through infiltration through cracks in pipes, through spills, and through dumping directly into catch basins. Not all illicit discharges are covered by Phase II. Unless they are identified as a significant source of pollution, the rule does not cover irrigation water runoff, water line flushing, infiltration through cracks in pipes, foundation drains, sump pumps, residential car washing, and street washing.
Mapping: Key To Success
Good system mapping is key to a successful Phase II program. A good map should show all intakes and discharge points of the storm sewer system and is useful in determining the amount and source of dry weather flows. Maps can also help in developing a program of BMPs by identifying pollution sources.
Generally, municipalities have less information on their storm sewer system than sanitary sewer and water distribution systems. The first step is to prepare a capital plan and obtain funding. Then, the owner must either make staff available or hire a consultant to complete the work.
All existing stormwater system information then should be collected and field verified. It may be necessary to walk along riverbanks and shorelines to locate all existing outfalls. Field verified information could be entered into a GIS database to be overlaid onto a map showing topography.
The new Phase II program components require new strategies for compliance. With the 2003 deadline fast approaching, now is the time to plan. EPA has prepared publications EPA 833-F-00-001, Fact Sheets 1.0, 2.0 and 2.5 Storm Water Phase II Final Rule, which are available on the web at www.epa.gov/owm/sw/phase2/.
About the author
Jennifer Lachmayr, P.E., manages projects at Weston & Sampson Engineers in Peabody, Mass. Her experience covers collection system infrastructure data collection, mapping, stormwater system improvements and BMPs.
