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4 TERRA VAC <br /> DRILLII�'G REPORT <br /> FORMER CHEVRON STATION 94054 <br />{ 2103 COUNTRY CLUB BOULEVARD <br /> STOCKTON, CALIFORNIA <br /> PROJECT No. 30-0212 <br /> 1.0 INTRODUCTION <br /> The site, located at 2103 Country Club Boulevard in Stockton, was formerly a Chevron Service <br /> Station. During October of 1988, six underground storage tanks (USTs) were removed from the <br /> a site. Subsequent environmental investigations have confirmed the presence of petroleum <br /> hydrocarbons in the soil and groundwater beneath the former service station site. Currently the <br /> site is a vacant lot. <br /> Groundwater monitoring data from two consecutive events for well MW-9, installed in March <br /> 1995, prompted Chevron Product Company (Chevron) to propose the installation of three <br /> additional groundwater monitoring wells down-gradient of the site. At the request of Chevron, <br /> Terra Vac prepeared and submitted a Work Plan Addendum for the installation of the wells, <br /> dated November 6, 1995, to San Joaquin County Environmental Health Department (SJCEHD). <br /> The wells.were installed to further delineate petroleum hydrocarbon impact to both soil and <br /> t <br /> groundwater down-gradient of the site. The Work Plan was approved by SJCEHD on <br /> November 29, 1995. <br /> 2.0 FIELD INVESTIGATION <br /> Prior to the start of work, Terra Vac obtained an Encroachment Permit from San Joaquin County <br /> Public Works Department and Well Permits from SJCEHD. Copies of the permits are included <br /> in Appendix A. On February 8, 1996, West Hazmat Drilling Corporation under the direction of <br /> Terra Vac, drilled and completed three groundwater monitoring wells (MW-10 through <br /> MW-12). The locations of the wells are included on Figure 1. A CME 75 truck mounted drill rig <br /> was used. Hollow-stem augers were used to drill the borings. The total depth of each well and <br /> screen interval were determined in the field based on PID measurements, lithologies, and <br /> groundwater levels. <br /> Soil samples were collected from each boring using a modified split-spoon sampler. The sampler <br /> was driven eighteen inches ahead of the augers using a standard 140 pound hammer repetitively <br /> dropped 30 inches. A minimum of three samples per boring were collected for lithology <br /> classification and volatile screening analysis. A hand-held PID (ProREA 75) was used to screen <br /> each set of soil samples collected for total organic vapors. The Unified Soils Classification <br /> System was used in the field to describe and log the lithology of each boring. Boring logs are <br /> included in Appendix B. <br /> Pmjai No,3M211 <br /> May 6, 1996 <br /> 4 <br />