SITE INFORMATION AND CORRESPONDENCE

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- 2 - 14 September 2006 (MW-1 through MW-3) were not destroyed prior to SJCEHD closure of the Site in 1997, but were retained for future monitoring by ARCO. Case #2: Subsequently ARCO terminated their business at the Site, and in August 2002 the remaining four 10,000-gallon gasoline USTs were removed. Confirmation soil samples obtained from the UST excavation pit contained detectable concentrations of TPHg, TPHd, Ethylbenzene, Xylenes, and MtBE. The maximum soil concentrations in 2002 were: TPHg, 400 mg/kg; Ethylbenzene, 1.2 mg/kg; Xylenes, 3 mg/kg; and MtBE 1.4 mg/kg. Petroleum hydrocarbons were also detected after the USTs removal in 2002 in groundwater extracted from the on-site monitoring wells. In October 2002, the maximum groundwater results (MW-2) were: TPHG, 410 pg/L; Benzene, 3.2 pg/L; Toluene, 8.5 pg/L; Ethylbenzene, 6 pg/L; Xylenes, 9.5 pg/L; MtBE, 3.7 pg/L; and 1,2-DCA, 26 pg/L. The latest soil (August 2002) and groundwater results (January 2006 monitoring) were compared to the San Francisco Bay Region Environmental Screening Levels (attached ESLs) for possible indoor air impacts, and the lowest Central Valley Region Water Quality Objectives (WQOs) for sources of drinking water in the following Table 1. Table 1 Petroleum Soil Results Region 2 Soil Groundwater Region 5 Hydrocarbon ESLS2 for Indoor ResultS3 Groundwater WQOs" Constituent Air Impacts TPHg 400 mg/kgo mg/kgUse soil gas 330 /L 5 pg/L TPHd Not analyzed Use soil as <50 /L 100 u /L Benzene <5 mglkg mg/kg0.18 ma/ka ma/k0.82 /L 0.15 N /L Ethylbenzen 1.2 mg/kg 390 mg/kg <0.5 pg/L 29 pg/L e Xylenes 3 mg/kg 310 mg/kg. 18 /L 17 /L MtBE 1.4 mg/kg 2 mg/kg 4.5 /L 5 /L 1,2-DCA Not analyzed 0.025 mg/kg 14 /L 0.4 N /L 1 —Concentrations in milligrams per kilogram (mg/kg). 2—San Francisco Bay Region Environmental Screening Levels (ESLs), excluding soil leaching to groundwater ESLs. 3 -Concentrations in micrograms per liter(Ng/L). 4 -Central Valley Region Water Quality Objectives (WQOs). 5— Numbers in bold exceed screening levels or WQOs. 6- No soil gas data available to evaluate potential for indoor air impacts. Table 1 shows that the analytical method detection limits for Benzene in soil exceeded the ESLs, while TPHg requires soil gas data (not available) and 1,2-DCA was not tested in August 2002. Table 1 also indicates that the January 2006 groundwater results for TPHg, Benzene, Xylenes, and 1 2-DCA exceed the WQOs.