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Geological Technics Inc Page 9 35500 Weltyty Road,Vernalis,CA Report-Preliminary Environmental Site Assessment Project No 248 2 February 6, 1995 4.2 Site Hydrology The exact depth to groundwater at this site is not known at this time However, saturated sediments were encountered at approximately 33 feet below the ground surface 4.3 Hydrocarbon Distribution in the Soil Soil samples were collected while drilling SB-1 and SB-2 This data is summarized and shown below as Table 1 Copies of the laboratory analytical reports are attached in Appendix A Table 1 Soil Analytical Data Ethyl Date Sample Benzene Toluene benzene Xylene TEPH TRPH /kR pg/kg ILg/kg pg/�g 01/20/95 SB-1 165-170' ND(<3 0) ND(<3 0) ND(<3 0) ND(<3 0) ND(<5) NA 01/20/95 SB-1 315-32 0' ND(<3 0) ND(<3 0) ND(<3 0) ND(<3 0) ND(<5) N A 01/20/95 SB-2 115-12 0' ND(<3 0) ND(<3 0) ND(<3 0) ND(<3 0) 17,200 N A 01/20/95 SB-2 215-22 0' ND(<3 0) ND(<3 0) ND(<3 0) ND(<3 0) 11,800 N.A 01/20/95 1 S13-2 315-32 0' 1 ND(<3 0) 1 ND(<3 0) ND(<3 0) ND(<3 0) 1 16,700 17,600 01/20/95 1 SB-2 33' wipe I ND(<30) 1 37 ND(<3 0) 1 42 1 167,000 44,000 ND=not detected (detection limits to parentheses) N A= not applicable The laboratory data suggests that the soil samples in SB-2 contain diesel range petroleum hydrocarbons possibly sourced from a fuel storage tank and not from the old Standard Oil pipeline The diesel fuel may have been used for firing the boilers used to heat crude oil before pumping it on down the line Oil, observed at the presumed groundwater interface (33 feet below grade) and identified as "SB-2 33' wipe", had the appearance of crude oil and not diesel This wipe sample was tested for BTEX, TEPH, and 418 1 and the laboratory data suggest that this darker oily material at the presumed water table interface is different from the diesel range petroleum hydrocarbons found in the soil samples taken above this This oil could represent crude leaking from the Standard Oil pipeline Low concentrations of toluene and xylene were found in the SB-2 33' wipe sample This crude oil is not expected to contain aromatic hydrocarbons, so the toluene and xylene may originally have been associated with the diesel 5.0 CONCLUSIONS AND RECOMMENDATIONS Geological Technics Inc concludes that evidence gathered during this . investigation suggest that a release of petroleum hydrocarbons has occurred in the vicinity of SB-2 The extent of the release has not been defined