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i5.0 PROPOSED SITE CHARACTERIZATION WORKPLAN <br /> Chevron U.S.A. Inc. proposes to complete the following worksteps to <br /> provide additional .information regarding subsurface conditions at <br /> the facility. To assess current groundwater quality beneath the <br /> site, three groundwater monitoring wells will be drilled and <br /> sampled (Figure o) . The wells will be situated to provide <br /> information regarding groundwater quality and flow direction <br /> beneath the site. One monitoring well will be located in the <br /> northeast corner of the Carration lease to monitor groundwater <br /> quality upgradient of the former fuel storage systems. Two <br /> monitoring wells will be located downgradient of the former tank <br /> pit location, to monitor water quality and to provide information <br /> regarding the local groundwater gradient. Exact well locations <br /> will be determined in the field and will be dependant on field <br /> conditions. <br /> 5. 1 Sampling Procedures <br /> All borings will be sampled at 5-foot depth intervals using a <br /> • split-spoon sampler with brass liners. The material from one <br /> sample ring will be described and field screened with a <br /> photoionixation detector (PID) for possible volatile organic <br /> content. A second ring will be sealed at each end with a Teflon <br /> sheet and plastic cap. The cap will be secured with polyethylene <br /> tape and the sample will be preserved on ice. Drill cuttings will <br /> be logged continuously by an qualified geologist or civil engineer <br /> using the Unified Soil Classification System. Descriptions of <br /> soils encountered and monitoring well constructions details will be <br /> recorded on boring/well logs. <br /> one sample from each boring, the sample collected directly above <br /> groundwater will be submitted to a state-certified laboratory for <br /> analyses. <br /> Between sampling events, equipment will be cleaned using a three- <br /> bucket wash system. In this system, the zings and samplers are <br /> Chevron U B A Inc r 357 3 <br /> R03t781 17.8 <br />