All the programs described in this report used a variety of tools with no one tool or combination being consistently effective. However, solids sampling by trap or catch basin grabs is a commonly used tool to characterize stormwater basins and trace upstream sources. Line cleaning and resampling can be effective to test the presence of ongoing versus legacy sources. Many programs have also found historical data (e.g., former land use, contaminated site databases) helpful in concert with conveyance system PCB chemistry to guide prioritization of more focused investigations. Business inspections have varied results and their success depends, in part, on owner experience and the strength of their relationship with inspectors. The final steps of source identification and control can be critically dependent on the available legal authority structure to grant property access and enforce cleanup actions.
The most common challenges facing PCB source tracing programs include a lack of public awareness of PCBs as a significant environmental contaminant that can have historical and ongoing sources, sampling logistics, laboratory analytical issues (e.g., detection limits, blank contamination), and a lack of clear legal and/or regulatory authority to complete source identification and control. The professionals interviewed recommended establishing partnerships and collaborations, combining resources and building on the work of others to most efficiently conduct PCB source tracing. Several jurisdiction staff also suggested planning ahead for data management, for both database design and funding.
Sources of PCBs are often industrial with metals recyclers and businesses associated with transformers among those identified by the reviewed source tracing programs. However, contaminated sites that were historically remediated can remain active PCB sources. In addition, in-use construction materials (e.g., caulk, sealant, paint) have been found to contain very high PCB concentrations (e.g., at a scale of 100,000 mg/Kg). The current TSCA regulations allow products to contain less than 50 mg/Kg and laboratory testing has confirmed some PCB congeners are present in off-the-shelf products. While legal, the inadvertent production of PCBs represents a new type of PCB source – different from the legacy Aroclor sources typically targeted by source control programs. These products contain fewer congeners and the relative importance of these as sources to the environment are unknown, at least with regard to toxicity. Regardless of source type, the stormwater pathway is often a major pathway of PCBs to receiving waters.
