A Case Study: Meeting Numeric Stormwater Criteria at a Foundry Site Through Model Application

Stormwater pollution from manufacturing sites is generally regulated under federal and state permit programs. Stormwater management requirements for these sites are often “management based” measures with the assumption that implementation of the management measures will achieve the desired stormwater quality. This paper describes an approach to achieving numeric stormwater permit requirements based on modeling of stormwater pollution loads and concentrations, along with the treatment measures constructed.“Numeric standards” as they might apply to stormwater regulations have received increased attention since the USEPA's Office of Wastewater Management and Office of Wetlands, Ocean, and Watershed memo: “Revisions to the November 22, 2002 Memorandum Establishing Total Maximum Daily Load (TMDL) Wasteload Allocations (WLAs) for Storm Water Sources and NPDES Permit Requirements Based on Those WLA's” in the fall of 2010. The analysis described in this paper could be one approach to meeting a numeric standard for stormwater pollution discharge.