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Chevron Products Company Page 2 Former Chevron Station#9-8632,575 Grant Line Road,,Trac..California July_16.2001 (bgs) Soil samples were generally collected at the capillary fringe and submitted for chemical analysis Based on pore pressure and on lithologic information collected from the continuous cores and the CPT logs, one to two depth-discrete groundwater samples were collected from each of the borings Soil and groundwater samples were analyzed for the presence of total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), benzene, toluene, ethylbenzene, xylenes (BTEX), and fuel oxygenates, including methyl tertiary butyl ether (MtBE), tertiary butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ELBE), tertiary-amyl methyl ether(TAME), 1,2-dichloroethane (1,2-DCA), 1,2-dibromoethane (EDB), ethanol, and methanol Upon completion, the borings were filled with grout from the bottom up and finished to surface grade with asphalt Field and laboratory procedures are presented as Attachment B The findings of this assessment are summarized below • Subsurface Conditions. Review of the boring logs and CPT profiles suggests silt mixtures with clay and/or clay mixtures with silt comprise the stratigraphy to an approximate depth of 30 feet bgs at all CPT locations At CPT-10 there was a thin sand layer encountered at approximately 24 feet bgs Groundwater was expected to be encountered at approximately 6 to 8 feet bgs based on recent groundwater monitoring events, however, groundwater was not observed until approximately 15 feet bgs in most of the boring locations CPT logs are included as Attachment C • Soil Analytical Results. Selected soil samples were submitted to a California state- certified laboratory and analyzed for the presence of purgeable hydrocarbons (i e TPHg), extractable hydrocarbons (1 e TPHd), BTEX, and nine fuel oxygenates Soil samples were collected from 8 of the 15 borings Soil analytical results are summarized 1n Table 1 Certified analytical reports and chain-of-custody documentation are presented as Attachment D TPHd was detected in all eight soil samples collected with concentrations ranging from 14 milligrams per kilogram (mg/kg) at CPT-1 (23 feet bgs)to 14 mg/kg at CPT-2 (7 feet bgs) The sample collected from CPT-2 at 7 feet bgs also contained TPHg and BTEX at 400 mg/kg, 2 3 mg/kg, 1 1 mg/kg, 10 mg/kg, and 5 mg/kg, respectively MtBE was not detected in any of the soil samples collected • Groundwater Analytical Results. Groundwater samples were submitted to a California state-certified laboratory and analyzed for the presence of TPHd, TPHg, BTEX, and the nine fuel oxygenates Groundwater samples were collected from the identified water- bearing zone or depth intervals with distinct pore pressure A minimum of one depth- discrete groundwater sample per boring was submitted for analysis Two groundwater samples were collected at CPT-10 and CPT-12 Groundwater analytical results are presented in Table 2 Groundwater analytical data are presented graphically in Figure 3 Certified analytical report and chain-of-custody documentation are presented as Attachment D TPHg was detected in eight groundwater samples at concentrations ranging from 55 micrograms per liter (gg/L) (CPT-12 at 16 feet bgs) to 3900 µglL (CPT-7 at 9 feet bgs) I 1Chevron1986321Reports12001 CPT sueassess doe