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Preliminary Subsurface Investigation <br /> City of Stockton, former Western Pacific Railroad Property,Stockton, CA <br /> May 27, 1992 <br /> W0601.1D <br /> 6.2 Groundwater <br /> Laboratory analysis recorded priority pollutant metals above method detection limits in the <br /> groundwater samples collected from wells MW-1 through MW-3. None of the levels detected <br /> exceeded the Total Threshold Limit Concentration values as listed in Title 22 of the California <br /> ' Code of Regulations; however, one sample contained concentrations of selenium (WPRR-MW3) <br /> above the State Primary Maximum Contaminant Level (MCL). No volatile or semi-volatile <br /> ' organics were detected in any of the samples analyzed by EPA method 8240 and 8270, <br /> respectively. The laboratory results for the water samples are presented in Table 4. Laboratory <br /> reports, chain of custody documentation, and laboratory QA/QC data, are included in Appendix <br /> H. <br /> 6.2.1 (Wells Located on Adjacent Sites <br /> IPThe seven new monitoring wells and two existing wells at the Banner Island property were <br /> sampled on March 18 and 19, 1992 (Figure 2). This site is located directly southeast of the <br /> ' former WPRR property and subsurface investigations were conducted concurrently at both sites. <br /> Laboratory analysis recorded priority pollutant metals above method detection limits in the <br /> ' groundwater samples collected from wells BI-MW 1 through BI-MW9. Although none of the <br /> levels detected exceeded the Total Threshold Limit Concentration values as listed in Title 22 of <br /> ' the California Code of Regulations, some of the samples contained concentrations of arsenic (BI- <br /> MW4 and 8), barium (BI-MW 1), chromium (BI MW 1 and 2), and selenium (BI-MW 1, 4, and <br /> 8) above the respective State Primary Maximum Contaminant Levels (MCL). These include <br /> selenium, the same metal that exceeded its MCL at the former WPRR site. The only volatile <br /> ' organic detected was acetone ( 120 parts per billion, ppb) in well BI-MW4. <br /> R041392.SAY 11 <br />