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7.0 SUMMARY <br /> • A 1,000-gallon UST was utilized in the northern portion of the site between 1976 and <br /> 1989. Subsurface petroleum hydrocarbon impact was discovered at the time of removal <br /> of the fuel storage system. Petroleum hydrocarbon impact extends to groundwater. <br /> • The subject site is situated within a mixed residential and commercial neighborhood in <br /> east-central Stockton. Extruded plastic piping was formerly manufactured on the <br /> property. The site is currently used for retail hardware sales, office space, and for <br /> recreational vehicle and boat storage. <br /> • A network of monitoring wells (shallow, mid-depth, and deep) has been installed to <br /> monitor groundwater flow direction and the extent of impact. East and southeast <br /> groundwater flow, and low groundwater gradients, have predominately been observed <br /> beneath the site. <br /> • According to SJCEHD personnel, groundwater in the area surrounding the site was <br /> measured as low as approximately 110 feet bgs in 1979. Depth to groundwater has <br /> ranged from approximately 42 feet bgs (200 1) to 69 feet bgs (1990) since monitoring was <br /> initiated in 1989. <br /> • GRO, BTEX, TBA, and 1,2-DCA impact the subsurface beneath the site. The vertical <br /> extent of hydrocarbon impact appears to extend to at least 138 feet bgs near the former <br /> UST area. The lateral extent of petroleum hydrocarbon and fuel additive impact appears <br /> to be adequately characterized. <br /> • SVE resulted in the removal and abatement of approximately 16,200 pounds of GRO <br /> from the subsurface between June 1994 and June 1997. <br /> • Based on soil samples collected during this investigation from the MW-13 well boring, <br /> which was advanced near the former UST area, SVE appears to have been effective in <br /> mitigating vadose zone petroleum hydrocarbon impact. <br /> • Petroleum hydrocarbon impact to soil and groundwater has also been reported at the <br /> former Sunland Gasoline/Stockton City Cab Company property at 2085 East Fremont <br /> Street, immediately north of the site. <br /> • GRO, BTEX, MTBE, TBA, ethanol, 1,2-DCA, and EDB impact have been reported <br /> beneath the Sunland uasolineiStockton City Cab Company property. Petroleum <br /> hydrocarbon impact to the subsurface appears to extend to at least 121 feet bgs at this <br /> site. <br /> K:1Apache Plastics\Reportsrapache-scm-assessment report2006.doc Page 18 STRATUS <br />