APPLICATION OF THE DQO PROCESS TO THE DELAWARE ESTUARY PCB TMDL PROGRAM

We applied U.S. Environmental Protection Agency's Data Quality Objectives (DQO) process to collecting the data needed for decision-making in support of the Stage 2 PCB TMDL program for the Delaware Estuary. The DQO process, which is a seven-step planning approach, was used to develop sampling designs for data collection activities that focused on the challenges of identifying significant sources of PCBs to the estuary so that appropriate control strategies can be implemented and refining the estimated loadings of PCBs from source categories (e.g., tributaries, point source, air flux) that are needed for the PCB fate and transport model. To guide the field sampling program, the DQO process produced standard operating procedures (SOPs) as well as sample acceptance criteria. The SOPs specified water and sediment sampling methods and sample handling procedures. Sample acceptance criteria included maximum PCB concentrations allowed in field and method blanks. The goal was to ensure that samples were collected in a consistent manner and yielded an accurate estimate of PCB concentrations; consequently, PCB concentrations data would be comparable among locations within a source category (e.g., among tributaries) and between media (e.g., water and sediment). To guide the analytical laboratory program, the DQO process produced performance and acceptance criteria as well as specific data reporting requirements. Performance criteria included minimizing the number of co-eluting congeners. Acceptance criteria included the maximum PCB concentrations allowed in laboratory method blanks and the minimum concentrations allowed for the recovery of PCB standards. Corrective actions to be taken for identified performance problems included reanalysis of field samples and returning to the field for additional sampling. The data reporting requirements included consistent application of data qualifiers (e.g., “J” value flags, non-detect concentrations). In addition, a specific format was required for reporting the analysis data in an electronic data deliverable. The goal was to ensure that samples were analyzed and reported in a consistent manner and yielded accurate and precise estimates of PCB concentrations; consequently, PCB concentrations data would be comparable among analytical laboratories. At the final step of the DQO process, the cost of the data collection design was evaluated in light of the challenges to be addressed and the available resources (i.e., time, staff, funding). A balance was achieved between the cost of obtaining field samples and conducting PCB analyses and increasing the number of samples to reduce the uncertainty in the estimated loading from each source category.