When polycyclic aromatic hydrocarbons (PAHs) were found in the Thea Foss Waterway, several parties contributed to the cleanup costs. One party, the Washington State Department of Transportation (WSDOT), did not participate—leading the U.S. Department of Justice to file a cost recovery lawsuit. We were retained as technical experts to identify chemical markers of this contamination and to determine its source and route of transport into the waterway.
Our scientists developed site-specific chemical signatures of PAHs. Using multiple lines of evidence, we identified the source as a former manufactured gas plant (MGP) connected to the waterway via a WSDOT-built storm sewer. We then created a historical reconstruction showing that the releases from the MGP site matched PAH patterns in waterway sediments during the period the storm sewer was active.
Integral provided expert analysis and testimony. Our work delivered evidence supporting the court’s conclusion that PAH discharges from the MGP site through the storm sewer contributed to remedial costs in waterway sediments.