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26 September 2003 • AGE-NC Project No. 02-0896 Page 2 of 9 2.2. UNDERGROUND STORAGE TANK REMOVAL According to San Joaquin County Environmental Health Department(EHD)records,two USTs were removed from the property on 30 November 1989. Tank No. 1, a 1,000-gallon unleaded gasoline UST, and Tank No. 2, a 2,000-gallon leaded gasoline UST,were located in a common excavation east of the former office building. Two soil samples were collected from the floor of the excavation beneath each UST(a total of four samples). The samples were analyzed at a laboratory for total volatile hydrocarbons (TVH) and volatile aromatics(benzene,toluene, ethyl benzene and xylenes; BTEX)using EPA Method 8020. Petroleum hydrocarbons were not detected in the samples collected beneath the USTs.However,an Official Inspection Report prepared by the EHD indicated that"odd odor noted in backfill like paint thinner" and "vapors were rising off soils". Based upon noted"odors"by the SJCEHD, two additional soil samples (one beneath each former UST location) were collected on 22 March 1990 (re-sampling). The Official Inspection Report prepared by the SJCEHD indicated that"no odor was detected during sampling,no discoloration was noted either".The two soil samples were submitted to a laboratory and analyzed for Volatile Organic • Compounds using EPA Method 8240, and TVH and BTEX using EPA Method 8020.No VOCs or TVH were detected in either "re-sample" soil sample. However, 0.035 milligrams per kilogram (mg/kg) of toluene was detected in the sample collected beneath the 1,000-gallon(southern)UST. 2.3. PREVIOUS SITE ASSESSMENT On 03 March 2003,AGE personnel conducted soil sampling activities at the site.A soil boring was advanced to a total depth of 50 feet below surface grade(bsg)before encountering refusal. Discrete soil samples were collected at 5-foot intervals beginning at a depth of 10 feet bsg. TPH-g was detected in soil samples PI-20, P 1-25, PI-30 and PI-35 at concentrations between 4.2 milligrams per kilogram (mg/kg) in sample P1-30 to 11,000 mg/kg in sample P1-20. Toluene, ethylbenzene and xylenes were detected in samples P1-25, P1-30 and P1-35, ethylbenzene and xylenes were detected in sample P1-20, and xylenes were detected in sample P1-40; at maximum concentrations of 3.1 mg/kg toluene(P 1-25), 11 mg/kg ethylbenzene(P 1-20)and 600 mg/kg xylenes (P 1-20).The sample collected from 50 feet bsg was non-detect for all target analytes.No additional target analytes were detected at or above laboratory detection limits in the samples analyzed. Analytical results of soil samples are summarized on Table 1. • Advanced GeoEnvironmental,Inc.