TRACKING SOURCES OF TOXIC POLLUTANTS TO ACHIEVE TMDL GOALS

Polychlorinated biphenyls (PCBs) and other toxic pollutants such as mercury are ubiquitous and often cause water quality impairment on a regional scale. As regulators develop total maximum daily loads (TMDLs) for these pollutants, the underlying question of how to locate and reduce the sources of the pollutants is often left unanswered. Authorities have begun to investigate toxic pollutant trackdown methods as part of ongoing TMDL development in the New Jersey/New York Harbor. The results will benefit efforts to develop achievable TMDLs elsewhere.While the sources of PCB contamination in the NJ/NY Harbor have not been fully quantified, the U.S. Environmental Protection Agency (EPA) identified municipal wastewater treatment plants (WWTPs) as significant contributors. At EPA's request, the New Jersey Harbor Dischargers Group (NJHDG), a consortium of sewerage authorities, initiated a PCB trackdown study at the Linden Roselle Sewerage Authority (LRSA). In the first study phase, samples were collected from the main sanitary sewer lines and analyzed for PCB congeners.Samples were collected using automatic water samplers and passive in-situ continuous extraction samplers (PISCES), a semipermeable membrane device that adsorbs PCBs from water over an extended sampling period (10 – 14 days). PISCES and whole water sampling methods were compared to evaluate the most practical and representative method for sampling PCBs in the sewer system. Comparison criteria included ease of sample collection, reliability, reproducibility, ease of analysis, cost, and the quality of the data for source identification. Results demonstrated the low cost and time-integrated sampling advantages of PISCES. Nonetheless, water sampling may be preferred because it provides more quantitative data and can be used to selectively monitor dry or wet weather PCB sources.Gas chromatography (GC) results for whole water samples showed elevated total PCB levels in the western portion of LRSA's sewer system compared to residential/commercial areas. This pattern was most distinct in dry weather. In two dry weather sampling rounds, total PCBs were 2.6 to 5.8-fold higher in the western sewershed compared to a largely residential/commercial area in the northwestern portion of the sewer system. Wet weather samples showed only slightly higher total PCB levels in the western sewershed compared to the northwestern sewershed. This similarity between sampling locations suggests a widespread wet weather source.