WCEC completed an in-depth feasibility and treatability study at a large scale gasoline release site in Montana where over 4,000 gallons of product infiltrated a complex fractured bedrock system that ultimately discharged to a highly sensitive surface water receptor. Remedial alternatives (RAs) were evaluated to comply with the US EPA Administrative Order which required eliminating discharge of contaminants to surface waters and intrusion of vapor phase constituents into five residences. The feasibility study considered the numerous permitting requirements, weighed benefits of each outcome against necessary impacts to public and private properties to implement the RA, and evaluated costs of implementation to ensure the response was economically viable.

WCEC used groundwater modeling outputs to design a groundwater interceptor trench for gradient control and dewatering along the shoreline of a pristine mountain lake at a gasoline-impacted, fractured bedrock aquifer in western Montana. The multi-partitioned trench was sized based on model results to supply a water treatment facility capable of handling 500 gpm. Modeling output supported development of best management practices (BPMs) for water quality monitoring of the treatment system effluent to comply with NPDES regulations.