ARCHIVED REPORTS - GROUNDWATER MONITORING WELL INSTALLATION AND LIMITED SOIL SAMPLING

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' in KLEINFELDER ' 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. Kleinfelder also drilled and installed three monitoring wells (MW-1, MW-2, MW-3) on the site. 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. ' Based on the analytical result, the baseline groundwater quality at the site can be characterized as having exceedences over the applicable Water Quality Goals (WQGs) for the metal selenium in one groundwater sample and the VOC methylene chloride in each of the three groundwater ' samples. 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 0.056 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 or a high background concentration. Other metals detected in the groundwater samples included barium, chromium, vanadium, and zinc. The detected concentrations of these metals were below the respective WQGs. ' The WQG for methylene chloride is 5 ug/1 and is also a PMCL. The detected concentrations of methylene chloride in each of the three water samples were 7.1 ug/l (MW-1), 33 ug/l (MW-2), 15 ' ug/l (MW-3). The concentrations of methylene chloride are shown to be higher in the upgradient water samples versus the downgradient sample suggesting an off-site source. Methylene chloride ' can be characterized as being widely used as an industrial solvent and as a paint stripper, and was also used in certain aerosol and pesticide products and in the manufacture of photographic film. Other VOCs detected included bromochloromethane (MW-2 only) with a concentration of 3.1 ug/l; and bromomethane (each well) with concentrations of 2.8 ug/l (MW-1), 2.3 ug/I (MW-2), and 2.7 ug/l (MW-3). The WQG for bromochloromethane is expressed as a USEPA Suggested No Adverse Response Level (SNARL) for toxicity other than cancer risk of 90 ug/1. The WQG for bromomethane is also expressed as a SNARL with a level of 10 ug/1 (Draft level at this time form Cal EPA) and 9.8 ug/l as a USEPA Integrated Risk Information System (IRIS) Reference ' Dose as a Drinking Water Level (assuming 70 kg body weight, 2 liters per day water consumption, and 20% relative source contribution from drinking water). ' TPH-d and TPH-mo were detected only in the MW-1 sample (downgradient). The concentrations detected were 230 ug/l and 280 ug/l respectfully. The absence of either constituent noted in the soil samples collected from the 15' and 25' intervals of the MW-1 boring and the non-detectable ' concentrations noted from the soil boring samples and groundwater collected from MW-2 and MW-3 suggests the possibility of an on-site source upgradient of MW-1. 42162.1301 /ST04R854 Page 20 of 22 Copyright 2004,Kleinfelder,Inc. July 1,2004