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., v.. ..r <br /> Work Plan for Environmental Investigation May 18, 1989 <br /> Proposed ARCO Station Woodbridge, California AGS 39044-1W <br /> o Collect and classify relatively undisturbed soil <br /> samples at 5-foot intervals or observed soil changes to <br /> the termination of soil borings. The soil borings will <br /> terminated approximately 15 feet below the ground-water <br /> surface, unless a 5-foot-thick low permeability zone is <br /> encountered below the ground-water surface, or at <br /> refusal of the boring. <br /> o Construct 4-inch-inner-diameter ground-water monitoring <br /> wells in the boreholes. <br /> W <br /> o Develop and purge the wells and collect ground-water <br /> samples. <br /> o Analyze selected soil and ground-water samples for <br /> hydrocarbons in a laboratory certified by the State of <br /> California. <br /> o Survey the monitoring wells and selected site features <br /> using the services of a licensed land surveyor. <br /> o Evaluate ground-water flow direction and ground-water <br /> gradient beneath the site. <br /> o Interpret field and laboratory data to evaluate the <br /> extent of hydrocarbon contamination. <br /> o Prepare a report describing subsurface conditions at <br /> the site as revealed by the soil vapor survey and in <br /> the borings and wells; discussing the local geology, <br /> hydrogeology, and ground-water usage; interpreting <br /> laboratory results; and summarizing our findings, <br /> conclusions, and recommendations. , <br /> To locate areas of contamination onsite, we recommend that the <br /> soil-vapor probe be conducted prior to drilling soil borings and <br /> constructing monitoring wells. After the soil-vapor survey is <br /> conducted, the three ground-water monitoring wells will be <br /> constructed onsite in locations selected after considering the <br /> results of the survey and based on proposed locations of station <br /> 6 <br /> Apn/ied GeoSystems <br />