Laserfiche WebLink
Geological Technics Inc. Page 9 <br /> 35500 Welty Road, Vernalis,CA <br /> Report-Preliminary Environmental Site Assessment <br /> Project No.248.2 <br /> February 6, 1995 <br /> 4.2 Site Hydrology <br /> The exact depth to groundwater at this site is not known at this time. <br /> However, saturated sediments were encountered at approximately 33 feet -- -- <br /> below the ground surface. <br /> 4.3 Hydrocarbon Distribution in the Soil <br /> Soil samples were collected while drilling SB-1 and SB-Z. This data is <br /> summarized and shown below as Table 1. Copies of the laboratory analytical <br /> reports are attached in Appendix A. <br /> Table 1 Soil Analytical Data <br /> thyi <br /> Date Sample Benzene Toluene benzene Xylene TEPH TRPH <br /> l.Lg/ 1 1 1 mWkg <br /> 01/20/95 SB-1 16.5-17.0' ND(r3.0) ND(<3.0) ND(E3.0) ND(t3.0) ND(<5) N.A. <br /> 01/20195 58-1 31.5-32.0' ND(<3.0) ND(¢3.4) ND(<3.0) ND(r3.0) ND 0) N.A. <br /> 01/20/95 SB-2 11.5-12.4' ND(<3.0) ND(c3.0) ND(<3.0) ND(r3.0) 17,200 N.A. <br /> 01/20195 SB-2 21,5-22.0' ND(<3.0) ND(<3.0) ND(¢3.0) ND(E3.0) 11 844 N.A, <br /> 01/20/95 S3-2 31.5-32.0' ND 3.0) ND(r3.0) ND(<3.0) ND(<3.0) 1 17,600 <br /> 01/20/95 SB-2 33' wi e ND(<3.0) 37 ND(r3.0) 42 k67,000 44,000 <br /> ND=not detected (detection limits in parentheses) N.A= not applicable ( -7 <br /> b <br /> The laboratory data suggests that the soil samples in SB-2 contain diesel range <br /> petroleum hydrocarbons possibly sourced from a fuel storage tank and not <br /> from the old Standard Oil pipeline. The diesel fuel may have been used for <br /> firing the boilers used to heat crude oil before pumping it on down the line. <br /> Oil, observed at the presumed groundwater interface (33 feet below grade) and <br /> identified as "SB-2 33' wipe", had the appearance of crude oil and not diesel. <br /> This wipe sample was tested for BTEX, TEPH, and 418.1 and the laboratory <br /> data suggest that this darker oily material at the presumed water table <br /> interface is different from the diesel range petroleum hydrocarbons found in <br /> the soil samples taken above this. This oil could represent crude leaking <br /> from the Standard Oil pipeline. <br /> Low concentrations of toluene and xylene were found in the SB-2 33' wipe <br /> sample. This crude oil is not expected to contain aromatic hydrocarbons, so <br /> the toluene and xylene may originally have been associated with the diesel. <br /> 5.0 CONCLUSIONS AND RECOMMENDATIONS <br /> Geological Technics Inc. concludes that evidence gathered during this <br /> investigation suggest that a release of petroleum hydrocarbons has occurred <br /> in the vicinity of SB-2. The extent of the release has not been defined <br />