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CRYSTAL CREAMERY - STOCKTON <br /> WKA No 1628 01 <br /> • March 17, 1994 <br /> Page 6 <br /> To evaluate the extent of petroleum hydrocarbons in ground water detected during previous <br /> sampling and testing, we will drill two soil borings and convert them to four-Inch diameter <br /> ground water monitoring wells near the northern and western site boundaries The borings will <br /> be drilled using a truck-mounted drill rig equipped with hollow-stem augers at locations shown on <br /> Plate 4 Soil samples will be obtained from the borings at five-foot maximum intervals or <br /> changes in lithology until ground water is encountered Soil samples will be screened ;n the field <br /> using an organic vapor analyzer (OVA) and selected samples submitted to a California-certified <br /> laboratory for analysis of TPH as gasoline, using Modified EPA method 8015, and Benzene, <br /> Toluene, Ethylbenzene, and Total Xylenes (BTEX), using EPA method 8020 The materials <br /> encountered during drilling will be logged by an experienced field geologist and all work will be <br /> performed under the direct supervision of a California-registered geologist Soil <br /> boring/monitoring well permits will be obtained from San Joaquin County prior to start of <br /> drilling <br /> Ground water quality beneath the site will be evaluated by obtaining water samples from the new <br /> monitoring wells, and from well MW2 (if approved by the City of Stockton) located on the <br /> southerly adjacent WPRR property We also will collect water samples from the four existing <br /> monitoring wells (MW 1 through MW4) at the same time as part of our quarterly sampling <br /> Water samples will be analyzed for TPH as gasoline using EPA modified method 8015, and <br /> BTEX using EPA test method 602 The water samples will not be tested for lead based on the <br /> former tank having only contained unleaded gasoline, nor for TPH as diesel or motor oil based <br /> on the site having no history of diesel or motor oil contamination The trace concentrations of <br /> motor-oil-range hydrocarbons detected in previous water samples may be related to the natural <br /> organic material in soils beneath the site A travel blank prepared by the analytical laboratory <br /> will be analyzed for any compounds detected A description of field sampling procedures is <br /> contained in Appendix A, our site safety plan is attached as Appendix B <br /> Reporting <br /> All reports will follow the recommendations outlined in the Tri-Regional Board Staff <br /> Recommendations for Preliminary Evaluations and Investigation of Underground Tank Sites, <br /> August 30, 1991 Subsequent to field investigation, the data generated will be evaluated and, if <br /> NA <br /> WALLACE•KJHL <br /> R­!e par, Er ASSOCIATES INC <br />