Soil and Groundwater Impacts at Whitneys Chevrolet

TRC is working with Whitney’s Chevrolet, an automotive service facility in Montesano, Washington, and the Washington State Department of Ecology (Ecology) to delineate soil and groundwater impacts from multiple sources on several parcels and design a cleanup action to address the impacts. Groundwater impacts extend off-site, and TRC conducted the assessment activities required by a negotiated Agreed Order with Ecology and other local agencies. The activities conducted as part of a remedial investigation and feasibility study (RI/FS) include soil gas sampling, indoor air sampling, groundwater monitoring, well installation, underground storage tank (UST) removal and assessment, and light non-aqueous phase liquid (LNAPL) assessment and removal. TRC developed the site conceptual hydrologic model used as the framework for data evaluation and technology screening to develop a feasibility study for site remediation. TRC designed a remedial option that includes air sparging and soil vapor extraction (AS/SVE) technologies to address the impacts. Groundwater impacts include gasoline–range organics, aromatic hydrocarbons, fuel additives, and volatile organic compounds (VOCs) including tetrachloroethene (PCE).

During all phases of the characterization and assessment procedures, TRC worked diligently with Whitney’s personnel for minimum disruption to their sales and service activities. TRC turn-key assessment services served to sufficiently characterize the nature and extent of the impacts to the Whitney’s Chevrolet property, design an appropriate remediation system to address the impacts, and satisfy the requirements of the Agreed Order with Ecology. TRC continues to conduct quarterly groundwater monitoring and began implementing the selected cleanup action in the fall of 2016.