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Executive Summary <br /> 1 <br /> This report presents the results of the soil and groundwater investigation conducted at the <br /> ' intersection of State Route (SR) 120 and North Ripon Road, San Joaquin County, California <br /> (Figure 1). The property is located at Post Mile (PM) 9.82 of SR 120. The California <br /> ' Department of Transportation (Caltrans) proposes shoulder widening and intersection <br /> improvements at selected locations of SR 120 including the aforementioned project area. Part of <br /> ' the rehabilitation of SR 120 will require ROW acquisitions. The purpose of this investigation is <br /> to determine the presence or absence of hazardous concentrations of fuel hydrocarbons within <br /> the aforementioned project area. The information obtained by this project will be used to <br /> ' determine potential costs and liabilities as well as protect worker health and safety. <br /> ' Previous Initial Site Assessments (ISAs) identified the property as a former service station. <br /> Further field and archival research indicated that the location had formerly operated as a <br /> Mohawk gas station and that the service station was put out of business after a vehicle crashed <br /> ' into the pump island. <br /> ' A geophysical investigation was performed at the parcel under Task Order l O-OA7400-NY. The <br /> findings from the geophysical investigation suggested that tanks beneath the pump island had <br /> been removed; however, San Joaquin County Environmental Health Department(SJCEHD) <br /> indicated that they had no records of a tank removal at the site. The geophysical investigation did <br /> identify an anomaly indicating that an underground storage tank (UST),possibly a waste oil <br /> tank, may still exist at the site. Site reconnaissance located the presence of piping, possibly vent <br /> pipes or fill spouts, at two locations where magnetic anomalies were detected. All information <br /> ' gathered suggest a significant hazardous waste concem within the project limits. <br /> The first phase of the investigation performed on March 13, 2002 consisted of drilling up to six <br /> ' soil borings using direct-push sampling equipment. Groundwater was not encountered in this <br /> phase of the investigation as site geology prevented the direct push drilling from reaching first <br /> ' groundwater. <br /> The second phase performed on May 20, 2002 consisted of drilling two soil borings, using <br /> hollow stem auger drilling techniques, to first groundwater. Groundwater was encountered at <br /> approximately 11.4 meters (38.0 feet) below ground surface and groundwater grab samples were <br /> ' collected from the borings. The results of the investigation is summarized below: <br /> ' • Petroleum hydrocarbons were not detected in soil samples during this investigation. <br /> -IISACRFPIICOMMOMSWDP11O02iPR.APJMA834760.2n.dX IV <br />