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ME 4. <br /> 3 <br /> t <br /> groundwater is estimated at approximately,lU feet.bgs.: ,The.boreholes-will;bel backfilled:with- <br /> u,bentonite-cement grout:parnptd through-a,tremie:pipe.. . typical borehole diagram is shown.. <br /> on Figure 2. <br /> All drill cuttings will be stored on, and covered by, plastic on site, pending analytical <br /> results. Disposal of soil Will be the responsibility of ARCO. <br /> Soil Sampling During Drilling <br /> i <br /> Soil samples are collected during the drilling operations for three reasons., (1) for field <br /> identification of the borehole lithology, (2) for qualitative field screening for the 'resence of <br /> contaminants,and (3)for chemical analysis. <br /> 3 <br /> During the drilling operations,soil will be continuously cored to total depth,using a 5-foot- <br /> long continuous sampling device. The soil will be examined for lithologic characterization and <br /> . classified according to the Unified Sail.Classification System. Soil samples will be collected for <br /> laboratory analysis every 5 feet above groundwater. Samples will be obtained using a 2-inch- <br /> inside-diameter by 18-inch-long, split spoor.drive sampler lined with three 2-inch-diameter by <br /> j 6-inch-long brass tubes. The sampler will be driven into t:ndisturbed soil ahead ofthe augers <br /> i to obtain the samWes. <br /> in addition to evaluating the borehole lithology, the soil cores will be screened in the held <br /> with a photoionization detector (PID; or similar instrument. The lithology and PID reading of <br /> each sample will be recorded on the borehole log next to the depth interval from which the <br /> sample was obtained. <br /> i ' <br /> When the sampler is extracted from the borehole, the brass tubes will be removed and the ` <br /> ends of the tubes will immediately be screened for the presence of.hydrocarbons with a PID or s <br /> equivalent instrument. One sample pei: 5-foot sampling interval will be selected for possible <br /> chemical analysis on the basis of the highest PID reading. .':he ends of the selected brass tube <br /> i will be(1) covered with alurninum foil and plastic caps, which will then be taped with plastic <br /> type to provide an air-tight seal; (2)labeled and placed into zip-lock plastic bags; and(3)stored <br /> in a cooled ice chest for delivery to the analytical laboratory. These procedures minimize the <br /> i potential for cross contamination acrd volatilization of volatile organic compounds prior to <br /> chemical analysis. <br /> 11 J Iia drilled f doe ava and ba kftll <br /> backfille�r4alCVWIWi�I.na[ be_atial'�xed p s)`�wrlljbe +rollectec( <br /> < . <br /> 'ram 1 <br /> - i :. w.. ard:`an�Iyx front_, <br /> mr <br /> ; fiat vers t1 neaih'the backfilled materia! <br /> -- - ---- — - To prevent cross':contamination-during saiiipling, ill equipment will be washed with <br /> laboratory-grade detergent, rinsed with tap water, and rinsed with deionized water.before and <br /> between collecting each sample. <br /> 6661\juscVM14)2.wKw <br />