Laserfiche WebLink
' Since petroleum hydrocarbons were detected at depths of 40 and 50 feet in boring B1 (tank <br /> cavity), the PHS/EHD required a groundwater investigation Subsequently, three monitoring <br /> wells were installed at the site in March 1993 (see Section 3 3) <br /> 3.2 Initial Assessment and Drilling, October 1992 <br /> I On October 9, 1992, a soil boring was drilled in the center of the former gasoline tank cavity <br /> to a depth of 60 feet. Samples were collected at five-foot intervals and analyzed for total <br /> petroleum hydrocarbons (TPH as gasoline) and volatile aromatics (BTE&X) Analytical <br />' results are summarized in Table 4 GeoAudit concluded in the Soil Boring Installation <br /> Report dated November 16, 1992, that assessment of the extent of contamination could be <br /> achieved by further excavation The location of the soil boring is illustrated in Figure 3 The <br />' boring log for B-1 is included in Appendix D <br /> I TABLE 4 <br /> ANALYTICAL RESULTS FOR BORING B-1 (IN FORMER TANK CAVITY) <br /> Mid-Cal Leasing <br /> 1649 East Channel Street, Stockton, California <br /> October 9, 1990 <br /> (mg/kg) <br /> Sample TPH as Ethyl- Total <br /> ID Gas Benzene Toluene benzene Xylene Lead <br /> B-1-20 93 05 15 35 14 11 <br /> B-1-30 6100 31 520 170 520 NA <br /> B-1-40 13 021 2 6 037 13 NA <br /> B-1-50 ND 001 002-5 ND 0 007 NA <br /> B-1-60 ND ND ND ND ND 9 3 <br /> ND=Not detected NA =Not Analyzed <br /> 3.3 Monitoring Well Installation and Sampling, March 1993 <br /> On March 9 and 10, 1993, three soil borings were drilled at the site Each boring was drilled <br /> to a depth of 77 feet Samples were collected at five-foot intervals and selected samples <br /> p p Ales <br /> were analyzed for TPH as gasoline and BTE&X The borings were completed as <br /> groundwater momtonng wells MW-1 through MW-3 (see Boring Logs, Appendix D) A <br /> benzene concentration of 0 0079 mg/kg was detected at a depth of 45 feet in MW-2, lust <br /> I south of the tank pit Analytical results for soil samples collected from MW-1 through MW- <br /> 3 are presented in Table 5 Based on these and prior results, GeoAudit recommended <br /> further excavation to remove the contaminated soil At the request of Mr Gotelll, GeoAudit <br /> submitted an Interim Remediation Plan for overexcavation (see Section 3 5) <br /> G-I.S—1 Audi S.m e.J.c 4 <br /> 1,W dl R--d CSP4 6180.91 <br />