Remedial Action and Vapor Treatment System

Since 2004, MFA has provided environmental compliance, site investigation, and remediation for this retail fuel facility in Hillsboro, Oregon. Leaking underground storage tanks beneath the fueling station released gasoline to the environment, which led to the site’s listing on the Oregon Department of Environmental Quality’s (DEQs) Leaking Underground Storage Tank list. MFA managed the air sparge and soil vapor extraction remediation system operation and maintenance, groundwater monitoring, air monitoring, soil vapor monitoring, and reporting. All work has been carried out while allowing the client to simultaneously redevelop the site and operate the business successfully.

Monitoring was conducted to confirm the nature and extent of gasoline-range organic hydrocarbons and selected volatile organic compounds in the subsurface and to evaluate the effectiveness of remedial actions implemented since the leaking tanks were removed.

As a result of the remedial efforts, MFA developed a revised monitoring network that focuses on the residual contamination. Concentrations of hydrocarbons in groundwater are generally decreasing in monitoring wells, except for benzene in a few monitoring wells in the southern area of the site. The client evaluated options for addressing residual contamination in this area. A pilot study involving in situ chemical oxidation was conducted in 2010. The results of the pilot study included recommendations for continuing this remedy on the site. Following the pilot study, an in-depth interim assessment was conducted in conjunction with the routine monitoring, as requested by DEQ, to evaluate current conditions and to assess risk with respect to residual contamination.

The project involves in-depth communication and coordination between multiple parties, including property owners, consultants, attorneys, and DEQ. MFA provided support for insurance cost recovery to provide money for compensation and remediation. Settlement agreements between involved parties have established a trust fund to remediate the properties and obtain a No Further Action determination from DEQ. MFA will continue to manage the remedial efforts, consistent with stipulations set forth in the settlement agreement, the trust, and Oregon regulations.