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Preliminary Subsurface Investigation <br /> City of Stockton, former Western Pacific Railroad Property, Stockton, CA <br /> May 27, 1992 <br /> W0601 AD <br /> One groundwater monitoring well located at the Stockton Police Station (BI-PS) and one located <br /> at the Southside Channel Redevelopment site (BI-SCD7)were sampled on May 12, 1992 (Figure <br /> ' 3). These wells were selected for sampling because they had no prior history of hydrocarbon <br /> impaction and are considered to be "clean". <br /> Laboratory analysis indicated a majority of the Title 22 metals are above method detection limits <br /> in the groundwater samples collected from both wells. As with the former WPRR Property <br /> samples, none of the levels detected exceeded the Total Threshold Limit Concentration values <br /> as listed in Title 22 of the California Code of Regulations; however, some of the samples <br /> contained concentrations of arsenic (BI-SCD7), barium (BI-PS), chromium III (BI-PS), and <br /> ' selenium (BI-SCD7 and BI-PS) above their State Primary MCL. These include selenium, the <br /> same metal that exceeded its MCL at the former WPRR Property. <br /> The laboratory results are presented in Table 5. Laboratory reports, chain-of-custody <br /> documentation, and laboratory QA/QC data are included in Appendix H. <br /> 7.0 CONCLUSIONS <br /> ' Based on the results of this assessment and previous work performed at the site, RP.SNA <br /> concludes that: <br /> ' • Surrounding land use includes industrial and commercial properties. It appears that <br /> shallow as well as deep aquifers are impacted with respect to water quality on a regional <br /> ' level. <br /> • Studies by DWR, USGS, SJFCD, and sampling of adjacent sites have found groundwater <br /> that exceeds drinking water standards for a number of analytes including chloride, iron, <br /> manganese, TDS, arsenic, barium, chromium, and selenium in the Stockton area. <br /> R041392.SAY 12 <br />