Former Service Station, 952 Simmerhorn Road, Galt

Subsurface petroleum hydrocarbon impact was discovered at this facility in 1999, at the time of removal of the fuel storage and delivery system from the property. In 2000, Stratus began completing subsurface investigations at the site to comprehensively laterally and vertically characterize the extent of fuel contamination to the subsurface. During this work, it was determined that petroleum hydrocarbon / fuel oxygenate impact extended to the water table (located at approximately 70 feet bgs) and that a plume of these contaminants had impacted groundwater. Concentrations of GRO, benzene, and MTBE were historically reported at maximum concentrations of 15,000 µg/L, 8,200 µg/L, and 5,600 µg/L, respectively, in groundwater.

After fully characterizing the extent of the fuel contamination in the subsurface, Stratus conducted pilot testing to evaluate the feasibility of using SVE and GWE to mitigate the subsurface fuel contamination at this property. A remediation system was subsequently constructed; with operation of the remediation system occurring between April 2005 and February 2009. At the time of system shutdown, no petroleum hydrocarbons or fuel oxygenates were being reported in influent air samples extracted from the subsurface by the SVE system. Quarterly sampling of groundwater during a three-year post-remediation period revealed that shallow groundwater beneath the site has been completely remediated to background conditions.

Once remediation was complete, in order to evaluate the potential risk to human health due to vapor intrusion, a soil gas survey was planned and executed at the site. Stratus evaluated the results of the soil gas survey and compared the data collected to RWQCB-SF’s Environmental Screening Levels (ESLs); the results indicated that potential risk was apparent and the case was closed by SCEMD in early 2011.

The RP for this project was an elderly woman who had inherited the property, and environmental issues, via family. Through the 11 years Stratus was involved this project, Stratus obtained admittance into the UST Cleanup Fund for the RP, performed all work on a paid-when-paid agreement, and aggressively and responsibly managed the RP’s UST Cleanup Fund monies on her behalf. Closure of this site was achieved using only approximately 65% of the UST Cleanup Fund budget for the site, leaving more than a half million allotted dollars on the table.