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Site Background Information: Thater Property(former Tucker Construction) Page 2 of 3 SITE ASSESSMENT ACTIVITIES On 16 October 1985,JHK advanced one soil boring to a depth of 65 feet bsg for the installation of one ground water monitoring well(MW-1; Figure 2). The well was constructed of 2-inch diameter polyvinylchloride (PVC) casing with a 0.020-inch slotted screen installed from 35 feet to 65 feet bsg. Number 2 Monterey sand was installed to approximately 1 foot above the screened interval, with a bentonite seal above the sandpack. Soil samples were collected at 5-foot intervals from 10 feet to 45 feet bsg and transported under chain of custody to California Water Labs(CWL) for analysis. Soil samples taken at 35 feet(B1-35) and 40 feet bsg(B1-40)were analyzed for: • Benzene, toluene, ethylbenzene, and total xylenes (BTEX) and 1,2-dichlorobenzene, 1,2- dichlorobenzene, and 1,4-dichlorobenzene by EPA Method 602; and • Total petroleum hydrocarbons (TPH) and total lead. Benzene was detected in samples B1-35 and B1-40 at concentrations of 13.3 micrograms per kilogram(gg/kg: parts per billion)and 296 µg/kg,respectively. Xylenes were detected in samples Bl-35 and B140 at concentrations of 282 gg/kg and 27,000 gg/kg, respectively. Toluene was detected in sample B 1-35 at a concentration of 120 gg/kg.Ethylbenzene was detected in sample B 1- 40 at a concentration of 6,900 gg/kg. TPH was detected in samples B1-35 and B1-40 at concentrations of 68,000 gg/kg and 193,000 gg/kg, respectively. On 19 October 1985, monitoring well MW-1 was developed and ground water samples were collected for analysis. The samples were transported to CWL and analyzed for: • BTEX, 1,2-dichlorobenzene, 1,2-dichlorobenzene, and 1,4-dichlorobenzene by EPA Method 602; and • TPH and total lead. BTEX compounds were detected at concentrations of 21.2 micrograms per liter (µg/1: parts per billion)benzene,204 µg/l toluene, 12.4 gg/l ethylbenzene, and 1,440 gg/1 total xylenes. TPH was detected at a concentration of 16,000 gg/1; total lead was detected at a concentration of 110 µg/1. On 24 April 2001,ground water in monitoring well MW-1 was sampled by Central Valley Regional Water Quality Control Board (CVRWQCB) personnel and analyzed by California Laboratory Services (CLS) for: • BTEX, di-isopropyl ether(DIPE), ethyl tertiary-butyl ether(ETBE),methyl tertiary-butyl ether (MTBE), tertiary-amyl methyl ether (TAME), tertiary-butyl alcohol (TBA), 1,2- dichloroethane(1,2-DCA), and 1,2-dibromoethane (EDB); and Advanced GeoEn iron mental,Inc.