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Work Plan for Additional Site Assessment <br /> ARCO Facility No.5469 <br /> Stockton,California <br /> Page 2 <br /> Based on the analytical results, limited excavation of hydrocarbon impacted soil was <br /> performed in the vicinity of the north end of the two dispenser islands. Approximately <br /> 4 cubic yards of impacted soil was excavated from the north end of the western dispenser <br /> island. Due to subsurface utilities and native hardpan soils (encountered at approximately <br /> 3 feet bgs), only overlying pea-gravel was hand excavated from the north end of the <br /> eastern dispenser island. Throughout the project, approximately 60 cubic yards of soil <br /> and pea-gravel were excavated and removed from the site (IT, February 2000). <br /> In a letter dated February 2, 2000, the San Joaquin County Public Health Services, <br /> Environmental Health Division (PHS/EHD) requested further characterization of soil and <br /> groundwater at the site. The request was based on the findings of soil sampling <br /> performed during product line removal activities in February 1999. In response to the <br /> letter, the IT proposed to install three onsite groundwater monitoring wells. In a letter <br /> dated April 4, 1999, San Joaquin County PHS/EHD issued a Work Plan Approval Letter <br /> that requested additional wells be installed. On May 1, 1999, Delta submitted a Work <br /> Plan Addendum proposing a total of six onsite groundwater monitoring wells. <br /> Delta retained Woodward Drilling Company of Rio Vista, California to install six 4-inch <br /> diameter groundwater monitoring wells between June 5 and June 8, 2000. The location <br /> of the wells is shown on Figure 2. A Well Installation Report was submitted to <br /> San Joaquin County PHS/EHD on October 4, 2000. The site is currently on a quarterly <br /> monitoring program. <br /> WATER SUPPLY SURVEY <br /> Delta proposes to conduct a survey to identify potential water supply wells located within a <br /> 2,000-foot radius of the site. A review of the California Department of Water Resources <br /> (DWR) Files will initially be conducted. Delta will also contact California Water Services <br /> to obtain information on wells located within the area. A table and figure will be prepared <br /> showing the location of, and details associated with wells located within a 2,000-foot radius <br /> of the site. Results of the survey will be presented with the report documenting the findings <br /> of the additional subsurface assessment. <br /> SCOPE OF WORK; ADDITIONAL ASSESSMENT <br /> The primary objective of the fieldwork is to further assess the Iateral and vertical extent <br /> of petroleum hydrocarbon impact to soil and groundwater in the northeastern portion of <br /> the site. <br /> CAARC015469kWork Plan15469wrkpin.doc Delta <br /> 3/19/2001 <br />