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Sunland Gasoline May 18, 1000 <br /> 2085 Fremont Street,Stockton, California Page 3 <br /> Work Plan for the Lateral and Vertical Extent <br /> of Soil and Groundwater Contamination <br /> One (1) boring will be a deep boring and placed in the vicinity of B-1 (completed on <br /> February 22, 2000). Figure 3 illustrates the placement of proposed soil and <br /> groundwater monitoring wells. Since B-1 was terminated at 81.5' and soil samples <br /> were collected a 5' intervals, WB F proposes that soil sampling begin at 80' below <br /> ground level. A groundwater sample will be collected once groundwater has been <br /> encountered. <br /> One (1) soil boring will also be completed in the vicinity of B-1 using the cone <br /> pentrometry test method, (CPT). This will provide relevant iithological and <br /> hydrological data about the underlying materials. <br /> Three (3) soil borings will be completed across the site (Figure 3) in an attempt to <br /> define the lateral extent of soil contamination. These borings will be completed at a <br /> point 10' beyond the depth at which the field PID indicates that petroleum <br /> hydrocarbons are not detectable. These three (3) soil borings will be completed using <br /> a mobile mounted drilling rig employing the use of a hollow stem flight auger. Soil <br /> samples will be collected a 5' intervals and will be screened with a PID. A single <br /> groundwater sample will be collected from each boring., <br /> ■ Groundwater Monitoring Well installation: Completion of three (3) soil borings to a <br /> depth of approximately 75' below ground level. The groundwater table is <br /> approximately 58' below the surface. The placements of these wells are depicted in <br /> Figure 3. Soil samples from each boring will be collected at 5' intervals and a single <br /> groundwater sample will be collected once groundwater is encountered. Each sample <br /> will be screen with a PID for the presence of petroleum hydrocarbon contamination. <br /> ■ Quarterly Groundwater Monitoring: Groundwater samples will be collected from each <br /> monitoring well on a quarterly basis for one (1) year. This data will be used to <br /> determine the levels of contamination present in the groundwater and to track the <br /> change in contamination over time. Based on this information, a determination of the <br /> most efficient and economical method of remediation can be proposed. <br /> ■ Receptor Survey: This survey will attempt to identify all domestic, municipal, <br /> agricultural, and industrial wells within a 2,000' radius. A physical search of the area <br /> will also be conducted to help identify wells. The survey will also analyze the <br /> influence of well pumping with respect to the migration of contamination from the <br /> subject site to potential receptors and the resulting threat to human and environmental <br /> health. <br /> 3.1 Drilling <br /> Permits will be obtained, as necessary, for the borings before drilling begins. The <br /> borings for the monitoring wells and four (4) of the soil borings will be <br /> accomplished using a mobile mounted drilling rig employing the use of a hollow <br />