Quantifying Impact of Transportation Runoff on Waterway Sediment
The Problem
Our client owns and operates highways, bridges, maintenance facilities, and stormwater outfalls. Stormwater runoff from these transportation facilities is conveyed via public and private outfalls to a contaminated urban waterway. Numerous industrial and manufacturing operations have been conducted along the waterway for more than a century, including shipbuilding, petroleum storage and distribution, metal salvaging, and electrical power generation. Our client required allocation support to distinguish potential contamination resulting from stormwater discharges from other historical and/or current contaminant sources along the waterway.
The Solution
TIG combined research, environmental sampling, chemical forensic analysis, and sediment chemistry modeling to determine the specific contaminants associated with the transportation facility and quantify the influence of our client facility on sediment quality within the waterway. The project included evaluating potential historical and current contaminant sources, determining contaminant fate and transport, and chemical fingerprinting to isolate our client’s stormwater runoff signature and distinguish its potential influence on sediment quality in the waterway. Based on this technical work, TIG was able to develop and apply an approach for a technically defensible allocation share for our client.
Value Added
TIG Environmental provided technical expert support at the site for environmental liability assessment and cost allocation for the remediation of sediments and for the associated natural resource damage claims. TIG’s evaluation provided our client with a scientific, quantitative assessment which remained largely indisputable in an advocacy setting and was relied on for negotiating a fair and equitable settlement with other parties as part of the allocation.
