Pederson’s Fryer Farms Site Cleanup

(Tacoma, WA)  Landau Associates conducted a remedial investigation (RI) and feasibility study (FS) on behalf of the Washington State Department of Ecology (Ecology) for the cleanup of petroleum-contaminated soil and groundwater at a former poultry processing plant that operated for about 50 years. The site historically had numerous underground storage tanks (USTs) at five distinct functional areas of the site that leaked gasoline, diesel, and heating oil into the soil and groundwater. The RI included drilling monitoring wells and evaluating soil, shallow perched groundwater, and deeper groundwater, using ground-penetrating radar to locate remaining underground storage tanks. Limited access drilling equipment was used to investigate a UST under a building (which Landau Associates has since decommissioned).

Landau Associates also conducted a vapor intrusion assessment that determined the carbon isotopic signature of benzene in indoor air, soil vapor, and aboveground sources as part of a forensic analysis to determine the source of benzene in indoor air. The vapor intrusion assessment included sampling of indoor air and sub-slab soil gas at a number of locations to assess the source of contamination in indoor air—the vapor intrusion pathway vs. off-gassing of indoor air sources. Only one sample location found contamination in indoor air and soil gas (one sample each), so a specialized analysis was run to fingerprint the two samples. It was concluded that contamination in the soil gas at this location was likely related to indoor air sources rather than subsurface contamination; that is, the assessment indicated that the vapor intrusion pathway was not an exposure pathway of concern for the FS.

A vacuum-enhanced groundwater extraction pilot test was performed to evaluate the feasibility of performing free product removal, and a clear water injection pilot test was performed to evaluate the feasibility of using injection technology for performing enhanced bioremediation. The results of the RI and the two pilot tests were used to assess remedial options worth screening during the FS. Feasible remedial options included technologies such as focused remedial excavations, enhanced bioremediation, soil vapor extraction, monitored natural attenuation, and ozone sparging. Due to the numerous cleanup locations at the site, four combinations of remedial options were evaluated as unique site-wide remedial alternatives. The FS included a disproportionate cost analysis to determine the preferred cleanup alternative.

Photo 3: Tacoma Public Library, Richards Collection