Stratus is currently providing environmental consulting and engineering services on behalf of a property owner and operator of a service station located at 2057 South El Dorado Street, Stockton, CA. Our services included: groundwater monitoring, sampling, and reporting; assessing the extent of an underground fuel release by drilling and installing groundwater monitoring wells; designing a remedial approach for the site (soil vapor extraction and groundwater pump and treat); and installing and operating remediation equipment. The work at the site will be successful in managing the environmental case at this facility to closure. 

The subsurface beneath the site is impacted with gasoline fuel contaminants including MTBE and TBA. Fine grained soils (silt/clay mixtures) have been predominately encountered in the subsurface, from surface grade to 120 feet below ground surface (bgs), the maximum depth explored. Relatively thin intervals of coarser grained soils have been observed at various depths, in particular between 15 and 20 feet bgs, 40 and 45 feet bgs, and 90 to 95 feet bgs. Based on the available data, these coarser grained soil strata appear to be heterogeneous and discontinuous. No thick, laterally continuous water bearing intervals were identified in the upper 100 feet of the saturated interval (below about 20 feet bgs). California Regional Water Quality Control Board in Sacramento oversees the assessment and remediation of contamination at this property. 

After investigating the extent of contamination and evaluating geologic conditions in the area, Stratus developed a cleanup approach that involved soil vapor extraction and groundwater extraction and treatment. The vadose zone was remediated quickly using Soil Vapor Extraction (SVE), however dissolved phase impact needed longer duration to remediate, particularly TBA and MTBE. The traditional pump treat system using liquid phase carbon was unable to adequately filter the dissolved TBA. Therefore, Stratus conducted a series of experiments to supplement the activated carbon filtration system to reduce TBA concentrations. Stratus was successful in isolating and identifying a dosage of peroxide injection to the primary holding tank, to reduce TBA concentrations in groundwater prior to carbon filtration. Remediation is still ongoing and we believe that our efforts will result in closure of environmental case at the site. Stratus has assisted the property owner in submitting reimbursement requests and receive money from the California USTCF to support the remedial effort.