OPTICAL BRIGHTENERS FOR ILLICIT DISCHARGE SURVEYS

The U.S. Environmental Protection Agency defines an illicit discharge as “any discharge to the municipal separate storm sewer system that is not composed entirely of storm water, except for discharges allowed under a NPDES permit or waters used for firefighting operations” (U.S. Environmental Protection Agency, 2000). Illicit discharges enter the storm sewer system through either direct connections, such as wastewater piping connected to the system, or indirect connections such, as infiltration from sanitary sewer pipes or failing septic systems and illegal dumping. These discharges result in high levels of pollutants and bacteria released to nearby waterbodies, which threatens the receiving water quality and public health.Segments of the Lynnhaven River and its tributaries have been designated by the State as impaired waters for fecal coliform contamination; the river water quality is in sufficient violation of bacterial standards for its prescribed designated uses of shellfish consumption and primary contact recreation. As a result, many segments of the river are listed as impaired on Virginia's 303(d) Total Maximum Daily Load Priority List. Furthermore, since performing source characterization studies on water samples collected, the State has suggested that the fecal coliform bacteria found in Lynnhaven River waters is at least partially of human origin (Virginia Department of Environmental Quality, 2004).To better understand the problem, in 2004 the City of Virginia Beach took the initiative to investigate potential sources of sanitary wastewater entering the Lynnhaven River via the storm drainage system. To accomplish this goal, the City's consultant proposed an innovative low-cost, low technology technique to screen for human waste signatures and conducted an optical brightener monitoring (OBM) field study.This paper will describe OBM as an emerging technique to quickly and cost-effectively facilitate a comprehensive survey of illicit discharge entering the storm sewer system and compare it to more expensive techniques. Furthermore, using the Lynnhaven River Watershed study as an example, the paper discusses optimal site selection, storm drain network investigations, recommendations and implementation of effective local actions to improve water quality and safeguard public health based on the survey results.