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En _J. <br /> i"�. '�;;y p-• ,�':k�i}r � Sx,-.n rr�'T-i7'�`.�xi��:9 a`1ti-�T�' :k`:�i�, 'kv�--r".� F'�,1� ��L F �� A `'Y �.._±r �+w.,. 'i,"�,Y'�h <br /> SINAI.REMERTAT7ON PIAN <br /> Shell Oil Compatsy <br /> 620 West Charter Wary,St:ckton,California <br /> Delta Project Into.40•S8-586 <br /> ' Page 5 <br /> 3.o PRO ECF Sl'TF.IWOROGI:OI.H FSCItIPTION AND APIALyFICAI,ItIwSUI.TS <br /> 31 Site Soils and Geolou <br /> In February 1989,eight soil borings(SB-1 through SB-8)were advanced to depths ranging from 15 to 30 feet <br /> H} below grade. During the months of December 1959,January,and March 1990,Delta advanced a total of <br /> nine soil borings to depths of approximately 40 feet below grade and completed each boring as a ground <br /> water monitoring well (MW-1 through MW-9). Soil boring locations and monitoring well locations are <br /> illustrated in Figure 3. Soil boring logs containing descriptions of soil conditions for the late 1989 and early <br /> 1990 drilling events are included in Appendix B. Monitoring well construction specifications are included <br /> in Appendix C <br /> Information gathered from the soil borings advanced by Delta indicate the soils underlying the site from the <br /> surface to 25 feet below grade consist,predominately of,sandy'and"clayey-sllt. A silty sand unit was <br /> encountered between approximately 25 and 35 feet below grade. Interbedded sand units were encount'=red <br /> between approximately 30 and 40 feet beltnv grade. A gravel backfilt was present to a depth of 14 feet below <br /> grade in the vicinity of monitoring well MW-2,where the former gasoline storage tanks were located. Soil <br /> cross-sections have been prepared to illustrate the inferred subsurface soil relationships. Cross-section <br /> locations are illustrated in Figure 4,and the cross-sections are presented as Figures 5(AW)and 6(B-B'). <br /> 3.2 So[I Anal testi Results Dlstrihutiou of Petroleum Constituents in Soils <br /> Sof samples obtained from tare soil borings at 5-foot vertical intervals were field-analyzed for the presence <br /> of petroleum hyurocarbon vapors utilizing a portable photoionization detector or similar device. Soil vapor <br /> screening measurements are included on the soil boring logs(Appendix B). Soil samples were selected for <br /> chemical analysis on the basis of screening results and the location of the soil sample in relation to the water <br /> table. Soil samples were submitted to a state-certified laboratory and analyzed for benzene, toluene, <br /> ethylbenzene,and xylenes(BTEX),and total petroleum hydrocarbons(9TH)as gasoline. Analytical results <br /> for soil samples collected during the February and December 1989,and January and February 1990,drilling <br /> events are summarized in Table 1.Soil boring locations are illustrated in Figure 3. <br /> r <br />