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&— Work Plan for Extended Site Ch*ffl�cterization: 7500 West Eleventh Street, Tracy. CA.%"0' Page 9 <br /> Sim unknown function was exhumed when the underground storage tanks were removed from the. <br /> site. <br /> ;.. Well MW-11 will have a total depth of 38 ft. and will be screened over a 30-ft. interval from <br /> just above the groundwater table to a depth of 37 ft. The construction details of the well will 1 <br /> be similar to that shown on Figure 7. The well depth and construction details have been <br /> selected based on the results of analyses of soil and groundwater samples recovered from a <br /> small-diameter boring (PP-7) drilled at essentially the same location during the first phase of <br /> site characterization work conducted at this site in 2000. Soils in that boring were found to <br /> +— have been affected by fuel hydrocarbons to a depth of at least 20 ft., although only diesel- <br /> range hydrocarbons at a very low concentration of 2.5 mg/Kg were detected at that depth <br /> (The San Joaquin Company Inc, 2001 d). <br /> 6.3.5 SummM of Proposed Additional Groundwater-quality Monitoring Wells <br /> Following is a summary of the groundwater monitoring wells SJC proposes to install as part <br /> of the extended site characterization program. <br /> Well No. Total Depth Screened Interval Purpose <br /> Location <br /> ` MW-3A 36 ft. 30 to 35 ft. Investigate vertical extent of affected <br /> groundwater <br /> ` MW- 3B 51 ft. 45 to 50 ft. Investigate vertical extent of affected <br /> groundwater <br /> MW-8 22 ft. 7 to 21 ft. Define eastern limit of primary <br /> plume of affected groundwater <br /> MW-9 22 ft. 7 to 21 ft. Investigate down gradient limit of <br /> primary plume of affected <br /> groundwater <br /> MW-10 22 ft. 7 to 21 ft. Define western limit of primary <br /> plume of affected groundwater in <br /> down-gradient area <br /> MW-11 38 ft. 7 to 37 ft. Investigate groundwater quality at <br /> apparent source of secondary plume <br /> of affected groundwater near <br /> southern boundary of site <br /> 6.4 Well Drilling and Soil Sampling <br /> Permits for drilling the exploratory boring and construction of the proposed wells will be <br /> obtained from the SJCPHS. The monitoring well borings will be advanced using an 8-in., <br /> SJC <br />