Verdantas (as TIG Environmental) provided technical support to identify multiple sources of PCBs in an urban waterway by evaluating the potential nexus between the upland and overwater portions of a client’s facility and in-water contaminants. A confirmed nexus would result in the need for remedial action with associated response costs.

Verdantas used a sediment transport model, performed mass studies of PCBs, and conducted forensic analyses of PCB chemical signatures to fingerprint the different sources of PCBs in sediments to develop a cost allocation scenario.

By comparing the PCB signatures of multiple sources, Verdantas determined the nexus to the sediments for each PRP and the anticipated cost allocation. We demonstrated that PCBs adjacent to the client's facility did not originate from the facility’s current or historical operations, but instead from the operations of upstream or adjacent facilities. From our forensic analysis, it was determined that approximately 95 percent of the PCBs in the sediments adjacent to the client's facility were attributable to transport of contaminated sediments from surrounding areas and that the cost of cleanup should be allocated predominantly to other PRPs.