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l Report Seoond Ph&w Subsurface lnvewptan <br /> Cty of Stoeiaon, Banner lsknd, Stockton, CA <br /> May 20, 1992 <br /> W06M.1D <br /> 1 <br /> Soil samples were collected at a depth of 5.5 feet below grade in the 16 shallow boring and at <br /> five-foot intervals in the deep borings. The soil samples from borings SB1 - SB7, SB8 - SB14, <br /> and SB15 - SB16 (see Figure 3), were composited into three samples and analyzed by Sequoia <br /> Analytical Laboratories (Redwood City, CA). The soil sample collected at the water table <br /> h deep boring was also submitted to Sequoia Analytical. These five soil <br /> interface from eac <br /> utilizing EPA <br /> samples were analyzed.for EPA priority pollutant metals and volatile organics <br /> method 8240. Laboratory analysis did not detect any concentrations that exceeded State Total <br /> Threshold Limit Concentrations (TTLC). The only volatile organic compounds detected in the <br /> soil was toluene (0.130 parts per million, ppm) and xylenes (0.130 ppm) in composite 2. The <br /> results of laboratory analysis of the soil samples are summarized on Table 1 (from WaterWork, <br /> 1990). <br /> �N The two deep soil borings advanced during the phase I investigation were completed as 2-inch <br /> diameter monitoring wells (BI-MW-1 and BI-MW-2). The wells were purged and groundwater <br /> samples collected on November 6, 1989, according to the site's QA/QC Plan. The samples <br /> were submitted to Sequoia Analytical for analysis of EPA priority pollutant metals and volatile <br /> organics utilizing EPA method 8240. Laboratory analysis indicated that the groundwater <br /> samples contained levels of cadmium, chromium, and selenium that exceed state maximum <br /> contaminant levels (MCLs). In addition to the metals detected, 36 parts per billion acetone was <br /> reported in the sample from MW-1. The results of the laboratory analysis of the water samples <br /> are summarized on Table 2 (from WaterWork, 1990). <br /> 3.0 SITE GEOLOGY AND HYDROGEOLOGY <br /> The site is situated on level terrain comprised of Quaternary-Recent alluvial sediments and fill <br /> materials. The site is primarily underlain by silt and clay with zones of silty sand. The fill <br /> materials have reportedly included municipal solid waste as well as dredged material from the <br /> Roao�szswr 3 <br />