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INC.oig <br /> 6ETTLER - RYAN <br /> MONITORING WELL INSTALLATION REPORT AND <br /> VAPOR EXTRACTION PILOT TEST REPORT <br /> i <br /> at <br /> Former Unocal Service Station No 2859 <br /> 1665 Pacific Avenue <br /> Stockton,California <br /> ReportNo 240072 04-1 <br /> I <br /> INTRODUCTION <br /> This report presents the results of a subsurface investigation and remediation feasibility study performed <br /> by Gettler-Ryan Inc (GR)at the above referenced site The work was performed at the request of Unocal <br /> Corporation (Unocal) to further evaluate the extent of petroleum hydrocarbons in soil and groundwater <br /> on-site and off-site in the downgradient direction northeast of the subject site, and evaluate vapor <br /> extraction as a possible remedial technology to address the residual petroleum hydrocarbons in soil <br /> beneath the subject site The scope of work performed included obtaining the required well installation <br /> permits from San Joaquin County Public Health Services Environmental Health Division'(SJCPHn EnHinD) <br /> an <br /> and encroachment permit from the City of Stockton, updating the site safety p g <br /> groundwater monitoring wells, collecting soil samples, developing and sampling the newly installed <br /> monitoring wells, collecting groundwater samples from all monitoring wells, analyzing selected soil and <br /> groundwater samples, surveying well head elevations and locations, conducting a vapor extraction pilot <br /> test, and preparing a report documenting the work performed This work was requested by San Joaquin <br /> County Work performed was proposed in GR's Work Plan For Additional Subsurface Assessment <br /> (report ##240072 04, dated March 6, 2001), and approved by SJCPHS-EHD in a letter dated March 15, <br /> 2001 (Appendix B) <br /> SITE DESCRIPTION <br /> The subject site is a vacant lot situated on the southwest corner of Pacific Avenue and Walnut Avenue in <br /> Stockton, California (Figure 1) Former facilities at the site consisted of a station building, one 550 <br /> gallon waste oil underground storage tank (UST), two dispenser islands, and two 10,000 gallon gasoline <br /> USTs that shared a common pit near the center of the site Locations of pertinent site features are shown <br /> on Figure 2 <br /> PREVIOUS ENVIRONMENTAL WORK <br /> Kleinfelder, Inc drilled soil borings KB-1 through KB-5 in January 1988 These borings were drilled <br /> around the tank complex, adjacent to the product islands, and adjacent to the waste oil tank The highest <br /> Total Petroleum Hydrocarbons as gasoline (TPHg) were detected in bonngs KB-3 and KB-5 at <br /> approximately 20 feet below ground surface (bgs) at concentrations up to 239 and 370 parts per million <br /> (ppm), respectively, and benzene was detected in the two borings at up to 112 and 6 58 ppm, <br /> respectively <br /> 6747 Sierra Court , Suite J Dublin , California 94568 • ( 925) 551 - 1555 <br />