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Chevron Products Company 2 Former Chevron Service Station 9-8632,575 Grant Line Road,Tracy,California July 26 2002 The results of this investigation are presented below . Subsurface Conditions. The underlying lithology consists of silty clay to clayey silt mixtures to an approximate depth of 20 to 50 feet bgs at each boring location A clayey sand mixture was encountered in MW-5 at approximately 25 feet bgs to approximately 47 feet bgs Groundwater was generally encountered at approximately 5 feet bgs at each boring location Boring logs and well construction details are included in Attachment C Soil Selection and Analysis. Sol] samples were collected at 5-foot intervals and sent under chain-of-custody procedures to a California state-certified laboratory for analysis of total petroleum hydrocarbons quantified as gasoline (TPHg), total petroleum hydrocarbons quantified as diesel (TPHd), benzene, toluene, ethylbenzene, xylenes (BTEX), methyl tertiary butyl ether (MtBE), tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether(EtBE), tertiary-amyl methyl ether (TAME), 1,2- dichloroethane (1,2-DCA), 1,2-dibromoethane (EDB), methanol, and ethanol Soil samples were not collected from the shallow well MW-6A due to its close proximity to the deep well MW-6B • TPHg was detected at concentrations raging from 620 milligrams per kilogram (mg/kg) in the sample from MW-5 at 5 feet bgs to 29 mg/kg in the sample from MW-6B at 5 feet bgs • TPHd was detected in two soil samples at concentrations of 46 mg/kg in the sample from MW-5 at 10 feet bgs and 46 mg/kg in the sample from MW-7 at 10 feet bgs • Benzene was detected at concentrations ranging form 0 0036 mg/kg in the sample from MW-7 at 20 feet bgs to 0 34 mg/kg in the sample from MW-7 at 10 feet bgs • MtBE was detected once in the soil sample from MW-5 at 35 feet bgs at a concentration of 0 0014 mg/kg • TBA, DIPE, EtBE, TAME, 1,2-DCA,EDB, ethanol and methanol were not detected above their respective laboratory detection limits Soil analytical results are summarized in Table 1 Laboratory analytical reports and chain-of-custody documentation are presented in Attachment D Monitoring Well Development and Sampling. The monitoring wells were developed and sampled by Gettler-Ryan Incorporated (GR) as part of the second quarter 2002 monitoring and sampling event on April 30, 2002 Eight wells, MW-1 through MW-7 were sampled and analyzed for TPHg, TPHd, BTEX, and MtBE Wells MW-5, MW- 6A&B, and MW-7 were also analyzed for TBA, DIPE, EtBE, TAME, 1,2-DCA, EDB, methanol, and ethanol • TPHg was detected at concentrations ranging from 310 micrograms per liter(µg11) in the sample from MW-6A to 1,300 µg11 in the sample from MW-7 • TPHd was detected at concentrations ranging from 240 µg11 in the sample from MW-5 to 530 µg11 in the sample from MW-7 I\Chevron%986321Reports198632 well install SA2002 doc