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Wit <br /> CRYSTAL CREAMERY - STOCKTON <br /> WKA No 1628 01 <br /> May 9, 1991 <br /> Page 3 <br /> ' Deposits is variable but is likely to be over one hundred feet thick beneath the site The sods <br /> ' observed during the tank removal were brown and grey sands and silts <br /> The site hes within the San Joaquin Valley Ground Water Basin (California Department of <br /> Water Resources, 1986) The upper ground water table is expected to be unconfined and <br /> approximately 20 feet below grade, based on the Spring, 1990 Ground Water Elevation <br /> Contour Map published by San Joaquin County Flood Control and Water Conservation District <br /> 1 The AGS report indicates that ground water was encountered at depths of 16 3 feet in Boring <br /> B1 and 18 0 feet in Boring B2 The regional ground water flow direction is reported to be <br /> easterly <br /> PROPOSED SCOPE OF WORK <br /> 1 Based on the findings from previous soil sampling and testing and to comply with San Joaquin <br /> County Public Health Services underground tank closure requirements, further investigation <br /> 1bis recommended as described below <br /> We recommend that Monitoring Well MW-1 be sampled and analyzed for TPH-gasoline and <br /> BTX&E as described in Appendix B, Field Procedures Once TPH-gasoline and BTX&E ground <br /> water concentrations have been determined, we recommend that three to five soil borings be <br /> constructed to 25 feet below site grade or to ground water to better define the extent of soil <br /> ' contamination The locations of the proposed borings are indicated on Plate 2 If ground <br /> water contamination is found in MW-1, two of the exploratory borings may be converted to <br /> ' ground water monitoring wells to accurately define the local ground water flow direction and <br /> gradient Detailed procedures for drilling and sampling of soil borings and installation, <br /> development and sampling of ground water monitoring wells are included in Appendix B <br /> All borings will be backfilled to grade with cement grout Soil generated during boring <br /> activities will be placed in 55-gallon sealed barrels until laboratory tests are completed We <br /> will then make provisions for the appropriate disposal or treatment of any contaminated soil <br /> Once the soil contamination has been defined, a remedial plan will be developed for the <br /> ' contaminated sail If the proposed borings are found to be contaminated, additional borings <br /> may be required <br /> ' The materials encountered during drilling will be logged by an experienced field geologist and <br /> all work will be performed under the direct supervision of a registered geologist Subsequent <br />