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7 <br /> WALLACE•KUHL&ASSOCIATES.INC. <br /> WORK PLAN <br /> LATHROP PROPERTY <br /> June 20, 1990 <br /> WKA No. 1184.02 <br /> Page 2 <br /> property anticipated to have contained the subsurface fuel tanks. We encountered visual and <br /> olfactory evidence in two borings indicating soils contamination by petroleum hydrocarbons. <br /> Laboratory test results of one soil sample revealed a concentration of 7,600 parts per million <br /> total petroleum hydrocarbons at a depth of 11 feet. <br /> For a complete description of previous site activities, see our "Soil Boring Report," dated June <br /> 19, 1990, which accompanies this work plan. <br /> Proposed Scope of Work <br /> The scope of our work will include the drilling of a minimum of five exploratory borings (P1 <br /> through 136) in the area of the property where we previously encountered soils contamination, <br /> apparently the result of former leaky subsurface fuel tanks (Plate 1). The borings will extend <br /> to approximately 20 feet below existing grade or ground water, using a Mobile B61 drill-rig <br /> equipped with hollow-stem augers. All borings will be tremmie backfilled with grout from the <br /> total depth drilled to the ground surface. If ground water is encountered, a water sample will <br /> be taken through the hollow-stem augers. This method is intended only as a preliminary <br /> indication of potential ground water contamination. A description of our field procedures is <br /> appended. <br /> The closest leach field or septic system is greater than 100 feet from the nearest boring. All <br /> contaminated soil generated during drilling and any ground water purged during water <br /> sampling will be stored in sealed 55-gallon drums until laboratory tests are completed. We will <br /> then make provisions for the appropriate disposal of any contaminated soil and/or ground <br /> water. <br /> The materials encountered during drilling will be logged by a field geologist and all work will <br /> be performed under the direct supervision of a certified engineering geologist. All work will <br /> be in accordance with the Regional Water Quality Control Board and San Joaquin County <br /> Environmental Health Division protocol. Subsequent to field investigation, all analytical data <br /> will be evaluated and a report prepared which will include: <br /> • a site pian showing locations of field tests <br /> • logs of borings <br /> • laboratory test results with chain-of-custody <br />