A Laser-Induced Fluorescence (LIF) remedial investigation at a retail petroleum station in Walker, Minnesota resulted in the delineation of a substantial LNAPL body and associated dissolved phase plume which posed a risk to nearby vapor receptors and downgradient lake and municipal wells. As an interim remedial action, WCEC installed an automated free product recovery skimmer system which successfully removed over 4,000 gallons of gasoline from the site. To address the remaining contamination, WCEC completed multi-phase extraction (MPE) pilot tests utilizing our mobile, automated, multi-phase contaminant recovery system.

WCEC followed all required steps in the conceptual and detailed design processes outlined in MPCA CAD Guidance Documents including the completion of a Conceptual Corrective Action Design Report (CCAD), Pilot Test Work Plan, and Pilot Test Results Report. Feasibility analysis included both technical and economic considerations and updated cost proposals were submitted to the client and the MPCA Petrofund for each phase of the project. 

WCEC demonstrated MPE as an effective remediation technology at the site by achieving targeted outcome goals for site dewatering and LNAPL removal including recovery of 1,000 kg of hydrocarbons over a 4-day pilot test. Based on the results from the pilot study, WCEC proposed that the site be moved to full scale implementation and a Detailed Corrective Action Design Report was prepared. Following approval from MPCA, WCEC installed the full-scale MPE system which has been successful in reducing source area contaminant concentrations and mitigating risks to sensitive down gradient receptors.