For the first time, a Total Maximum Daily Load, TMDL, of persistent bioaccumulative toxins, PBTs, is being developed primarily using passive sampling. This Regional Applied Research Effort, RARE, project is a collaborative effort of USEPA NRMRL, USEPA Region III, USEPA ORD, USGS, WVDEP, and VADEQ. The project has expanded the historical use of SPMDs allowing accurate assessment of PCB and dioxin loadings in an area with complex surface, karst, and pseudokarst hydrogeology. The Commonwealth of Virginia has been evaluating our reliance upon sediment, fish, grab and high volume water sampling, and other biomarkers for source and risk assessment, watershed characterization, impairment listing, and seasonal loading potential. Validation of the benefits of SPMD technology are the upcoming Virginia Bluestone PCB TMDL and a West Virginia Bluestone TMDL being developed in the near future.

SPMD deployment for TMDL development requires an appropriate plan, in this case a detailed Quality Assurance Project Plan, QAPP. Plans should account for impairment basis; accurate flow monitoring and hydrology; seasonal effects; soil type; monitoring location selection; interstate, interagency, and stakeholder communication; site security (including vandalism and extreme weather events); ingress and egress; bioaccumulation; pollutant transport vectors; quality assurance; and quality control. Choosing the correct sampling and deployment devices require an understanding of the limitations and advantages of various technologies.

The project results suggest that most effects of temperature, facial velocity-turbulence, biofouling, and perhaps other environmental variables on the PBT analyte uptake rates with a range of SPMD-water partition coefficients can be determined from several different Performance Reference Compounds, PRCs. This study demonstrates that various types of PRCs yield similar results. Additionally, the complexities of the hydrology of the watershed, including the groundwater transport issues may be largely accounted for using monitoring site selection, accurate frequent/continual flow monitoring, and continual rainfall measurements.