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i <br /> EXECUTIVE SUMMARY <br /> The subject site is located at 1434 West Yosemite Avenue in Manteca, California and is currently <br /> I an operating BP Station and JackPot Food Mart owned by Time Oil Company The facility at the <br /> site has been operating as a gasoline service station since 1969 <br />' In September 1991, the undergound storage tanks and associated piping were replaced at the site as <br /> part of a routine facility upgrade Although the majority of soil samples did not contain detectable <br /> concentrations of hydrocarbons, laboratory analytical results of soil samples collected during the <br /> tank removal activities reported detectable concentrations of total petroleum hydrocarbons as <br /> gasoline up to 13,000 parts per million (ppm), benzene up to 4 2 ppm, and ethylene dibromide at <br /> 0 0065 ppm Based on these results, an environmental assessment was conducted at the site in <br /> August 1992 and December 1993 which included a soil gas survey, drilling and soil sampling of <br /> eleven soil borings, and converting four of the borings into groundwater monitor/extraction wells <br /> and three of the borings into soil vapor extraction wells A soil vapor extraction pilot test was <br /> subsequently performed on the vapor extraction wells <br /> The results of the investigation showed that approximately 1000 cubic yards of sandy soil is <br /> impacted with petroleum hydrocarbons A very stiff clay layer lying beneath the sand has apparently <br /> prevented petroleum hydrocarbons from impacting groundwater at the site above State or Federal <br /> action levels The soil however, has been impacted by petroleum hydrocarbons at levels that <br /> combined with the depth to groundwater(approximately 16 feet below ground surface) will require <br /> remediation <br /> Soil vapor extraction has been selected as an effective technology to remediate the soil impacted <br /> with petroleum hydrocarbons at the site The extracted soil vapor will be treated with an internal <br /> combustion engine equipped with a catalytic converter until hydrocarbon concentrations decrease <br /> to levels where granular activated carbon may be used Soil remediation and groundwater <br /> monitoring will continue at the site until hydrocarbon levels in the soil are no longer considered a I <br /> risk to the potential beneficial uses of the groundwater <br /> TOCL434 FRP ti1.AC[)R` <br /> NgpS{g2,p] �1 A.,-s 26 1994 <br />