New Storm Water Discharge Guidelines Proposed

One of the largest contributors to stream sedimentation is runoff from construction activities.EPA is seeking comments on its proposed guidelines to control the discharge of pollutants from construction sites. The proposal would require all construction sites to implement erosion and sediment control best management practices to reduce pollutants in stormwater discharges. This proposed rule is projected to reduce the amount of sediment discharged from construction sites by up 27 billion pounds each year.

Controlling water pollution through the NPDES system requires application of 2 types of controls. Dischargers have to meet water quality standards, which are the "safe" levels of pollutants allowed in state waters. The other is technological controls - treatment of the wastewater or runoff in order to reduce pollutants. All industries are expected to meet these technology controls, generally specified in the form of Effluent Limitation Guidelines (ELGs). EPA evaluates industry segments (e.g., steel manufacturing, chemical production, etc.) to determine what types of technological controls are available and appropriate for treating wastewater produced by that segment. As EPA explains it, "[e]ffluent limitations guidelines and performance standards are established by EPA for different industrial categories since the best control technology for one industry is not necessarily the best for another. These guidelines are developed based on the degree of pollutant reduction attainable by an industrial category through the application of control technologies, irrespective of the facility location. Using these factors, similar facilities are regulated in the same manner." U.S. EPA NPDES Permit Writer’s Manual, EPA-833-B-96-003 (December 1996), §5.1.2. Where EPA has not set national ELGs for an industry category or subcategory, technology-based limits are determined on a case-by-case basis by state permit writers and imposed in permits. The proposal by EPA is to develop ELGs for stormwater runoff from construction activities.

Stormwater is more diffuse and harder to capture than wastewater from industrial processes, and EPA generally relies upon best management practices, or BMPs, to control sediment runoff. If the BMPs are in place, the site is deemed to be using the appropriate technology. In this most recent proposal, EPA will require more than the BMPs in certain situations. For certain large sites located in areas of the country with high rainfall intensity and soils with high clay content, stormwater discharges from the construction site would be required to meet a numeric limit on the allowable level of turbidity, which is a measure of sediment in the water. In order to meet the proposed numeric turbidity limit, many sites would need to treat and filter their stormwater discharges.

The current WV construction stormwater permit does not expire until December 4, 2012, at which time the new ELGs will be added to the state permit, in whatever form they are adopted by EPA.