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j <br /> i <br /> ya <br /> excavation being the saturated zone (approximately 301 ) . The <br /> initial step of the excavation is to excavate soils radially 20' <br /> from the location of borehole #3. The initial excavation quanti- <br /> ty, as shown in Figure 3, will equal approximately 350 cu. yards <br /> of soil. The soil removed during this initial step will be <br /> ,. placed in three piles on plastic sheeting at the site. The piles <br /> will be for each vertical 10' of excavation (i.e., first pile <br /> from 0--10' vertically) . From these stockpiles, a single compos- <br /> ite sample will be collected. The compositing will be conducted <br /> by visually quartering each stockpile and collecting four sepa- <br /> rate samples from each pile (one per quarter) . The four separate <br /> samples will then be composited to provide a single sample for <br /> w each pile. The samples will then be analyzed within twenty-four <br /> hours for the following parameters: <br /> o Total Petroleum Hydrocarbons (heavy) (TPH) - EPA Method <br /> 8015 (mod) . <br /> o Benzene, Toluene, Xylene and Ethylbenzene (BTX&E) - EPA <br /> Method 8010. <br /> Any stockpile which exhibits TPH concentrations above 1000 mg/kg <br /> will be disposed of at a hazardous waste landfill. Any stockpile <br /> f " which exhibits TPH concentrations less than 1000 mg/kg will be <br /> "y shipped to Forward Inc. in Stockton for land spreading. <br /> 4 In addition, due to the depth of this excavation, the excavated <br /> s.- side walls will be laid back or shored to conform with applicable <br /> OSHA Regulations. Upon completion of the initial excavation., the <br /> sidewalls at a depth of 25' below the surface will be sampled. <br /> Four sidewall samples will be collected and analyzed (within 24 <br /> hours; sooner if required) for the same parameters as the stock- <br /> pile composite samples. If the sample's TPH concentration <br /> `. <br /> exceeds the 100 mg/kg, <br /> additional excavation in the direction of <br /> -x the remaining "high" chemical concentrations will be conducted in <br /> 10' increments. Sidewall sampling and excavation will continue <br /> until the sidewall TPH concer-trations are below the cleanup <br /> ;$ level. The sidewall sample analytical results will determine the <br /> disposal alternative for the additionally excavated soils. <br /> Should the stepped excavation extend to the borehole which <br /> exhibited non-detectable hydrocarbon concentrations, the maximum <br /> rx' quantity of excavation would be approximately 3,500 cubic yards. <br /> (" Based on the above summary of activities, the excavation project <br /> will be performed in the following manner: <br /> A. Access <br /> Arrangements will be made with San Joaquin County for access <br /> to the site for excavation personnel and equipment. Perime- <br /> ter fencing will ensure that unauthorized access to the site <br /> is denied. <br /> ~_ 4 - <br /> I ' <br />