ARCHIVED REPORTS - GROUNDWATER MONITORING WELL INSTALLATION AND LIMITED SOIL SAMPLING

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' KLEINFELDER decreasing to non-detectable levels at or above the laboratory reporting limit in 3 out of the 5 samples. In only one location (B-6) the concentration increased with depth from a non-detectable ' result at 2-feet to a concentration of 110 mg/kg result at 5-feet. Soil samples analyzed from the 1-foot depths from across a majority the site indicate lead ' contamination to at least that depth. Near the perimeter of the concrete pad located near parcels 11, 12, and 13 an area to a depth of at least 3-1/2 feet has been characterized as being impacted ' with lead. The 3-1/2-foot depth was chosen as an affected depth because of the previous WHF, Inc. report (dated August 9, 2001) results showing STLC concentrations greater than 5 mg/1 to a depth of 3-1/2-feet and Kleinfelder's results to a depth of at least 2-feet. The most acutely affected areas of the site with lead contamination appears to be centrally located near the south side of the concrete pad where contamination was shown to extend to at least 5-feet. Kleinfelder estimates that approximately 1,150 cubic yards of soil are affected with lead contamination. ' Please see the attached site map for details. Groundwater elevations ranged from -11.43 feet above msl to -12.22 feet msl. The depth to water ' was approximately 22 to 24 feet bgs. The groundwater flow direction was calculated to be towards to the east/southeast, with an overall gradient of 0.001 feet/foot. MW-1 is the downgradient well during this sampling event and MW-2 and MW-3 were the upgradient wells ' during this sampling event. Groundwater samples were collected for laboratory analysis at the site from each of the three ' newly installed monitoring wells. The groundwater samples were analyzed for CAM-17 metals, volatile organic compounds, TPH-d,TPH-mo, TPH-g, and ethylene glycol. Based on the analytical result, the baseline groundwater quality at the site can be characterized as having exceedences for the metal selenium in one well sample and methylene chloride in each of ' the three groundwater samples over the applicable Water Quality Goals (WQGs) as expressed in the "California Environmental Protection Agency Regional Water Quality Control Board, Central Valley Region, A Compilation of Water Quality Goals", dated August 2003. Selenium is 1 naturally occurring in some soil and groundwater within the San Joaquin Valley. Methylene chloride is a solvent which may be used for degreasing, in fumigants, textile and leather coatings, as a spotting agent, for dewaxing, an industrial solvent and as a paint stripper, used in certain ' aerosols, in the manufacture of photographic film and as a analytical lab chemical. The potential is there that the methylene chloride detected in the three water samples was a laboratory contaminant. However, it is unlikely since no methylene chloride was present in either laboratory ' blank (QC sample). The WQG for selenium is 0.05 mg/l and is expressed as a Primary Maximum Contaminant Level ' (PMCL). Selenium detected in the water sample collected from MW-2 had a concentration of 0.56 mg/l slightly above the PMCL for selenium. Selenium was not detected at or above the laboratory reporting limit for MW-1 or MW-3 which might suggest an off-site source upgradient ' to MW-2. Other metals detected in the groundwater samples included barium, chromium, vanadium, and zinc. The detected concentrations of these metals were below the respective ' WQGs. 42162.E0I /ST04R854 Page 2of22 Copyright 2004,Kleinfelder,Inc. July 1,2004