Each sediment site has a unique history of contamination, discharges, set of constituents of concern, and potentially responsible party (PRP) dynamics. As the clean-up costs in active sediment mega sites reach into the billions of dollars, equitable allocation of these costs among the PRPs has important implications regarding the magnitude of each party's financial liability.Experience has shown that working hand-in-hand with a client and their legal counsel, and then providing technical lines of evidence to support their legal strategy, often results in early settlements and more favorable clean-up costs.
This presentation will provide an overview of applications, benefits, and limitations of four simple yet well-established and scientifically defensible forensic methods that can reveal trends and additional information hidden in the existing field data; these methods include:
- Fingerprint analysis (chromatography signatures; stable isotopes; co-contaminants; mass ratios) – to identify and/or distinguish sources and origins of constituents of concern;
- Statistical methods (principal component analysis; polytopic vector analysis; advanced pattern recognition methods) – to find a perspective that tells the most information about the spatial and temporal relationships in the field data;
- Geochronology (radioisotope analysis; chemical horizons) – to identify the age of constituents of concern and net sedimentation rates; and
- Hindcast model simulations (contaminant fate and transport modeling) – to recreate and simulate historical conditions, discharges from different sources, and evaluate the contribution and spatial extent of contamination in different reaches of the system.
By using these tools in harmony along with the Site historical information (i.e., aerial images, insurance maps, historical practice documents), a more informed and nuanced understanding of many sediment sites have been provided. Recent case studies will be presented where these forensic methods have been used to reduce a PRP's financial liability through various mechanisms including generating multiple lines of evidence to support legal strategies, identifying previously undistinguishable sources of contamination, and investigating the validity of claims provided by other parties.