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Mr.Harlin Knoll January 31,2003 <br /> Work Plan for Vertical Assessment <br /> USA Service Station No. 65 <br /> Page 2 <br /> monitoring wells. Table 1 presents the historical groundwater elevation and analytical <br /> summary. <br /> Three gasoline underground storage tanks (USTs) and associated piping were removed <br /> and replaced on October 6 and 7, 1997. Approximately 500 cubic yards of hydrocarbon- <br /> impacted soil were excavated and removed from the site during these activities. <br /> Pinnacle prepared and submitted a Remedial Action Plan (RAP) in January 1999. The <br /> RAP recommended the construction, installation, and operation of a soil vapor extraction <br /> and air sparge system to mitigate the petroleum hydrocarbon impact to soil, and <br /> groundwater. <br /> On May 4 and 5, 2000, Stratus supervised the installation of two groundwater monitoring <br /> wells (MW-9 and MW-10) and one air sparge well (AS-1) in the vicinity of the active <br /> pump islands. Stratus also directed the installation of vapor extraction well VW-1 on <br /> May 2, 2001. The locations of the wells are shown in Figure 2. <br /> Monitoring well MW-5, located in the shoulder of Lower Sacramento Road, was <br /> abandoned on May 5, 2000, at the request of City of Lodi, due to a proposed widening of <br /> Lower Sacramento Road. <br /> Stratus oversaw the construction and installation of a Soil Vapor Extraction System <br /> (SVES) in July and August 2000. The SVES has removed and abated approximately <br /> 3,470 pounds of TPHG between August 15, 2000, and August 12, 2002. The SVES was <br /> shut down on August 12, 2002 due to low influent petroleum hydrocarbon <br /> concentrations. <br /> SCOPE OF WORK <br /> Exploratory site investigation data and groundwater monitoring activities conducted to <br /> date appear to have adequately characterized the extent of petroleum hydrocarbon impact <br /> between surface grade and approximately 50 feet below ground surface (bgs). Stratus <br /> proposes to advance three CPT borings (two onsite and one offsite) to an approximate <br /> depth of 100 feet bgs to further evaluate the vertical extent of impact to groundwater. <br /> The proposed locations of the borings are shown on Figure 2. <br /> Depth discrete groundwater samples will be collected between approximately 50 and 100 <br /> feet bgs to further assess the vertical extent of petroleum hydrocarbon impact to <br /> groundwater. Groundwater samples will be collected from water bearing intervals <br /> located up to 50 feet beneath the screened intervals of the monitoring wells onsite and <br /> downgradient of the site. <br /> IIAUSA Gasoline\0065\Workplans\usa65-cpt-workplan.doc OMAW5 <br />