COMPLIANCE INFO_FILE 3 - Laserfiche WebLink

Home Browse Search

Table 2 (Continued) Sample no. Diesel Benzene Toluene Ethylbenzene Xylenes U850-D1U1-13-23'(23.2') 12 <0.005 <0.005 <0.005 <0.005 U850-D1U1-13-29'(29.2') 4 — — — — U850-D1U1-13-33'(33.21 29 <0.005 <0.005 <0.005 <0.005 U850-DW1-14-24'(25.7) <2 <0.005 <0.005 <0.005 <0.005 U850-D1U1-14-29'(30.7') <2 <0.005 <0.005 <0.005 <0.005 U850-DW1-14-34'(35.7') <2 — — — — U850-DW1-14-39'(40.71 <2 — — — — U850-D1U1-14-44'(45.7) <2 — — — — U850-D1U1-ESP1-1.5' 16 — — — — U850-D1U1-ESP1-3.3' <1 — — — — • Indicates no analysis performed for this compound. < Indicates below detection limit. (#) Indicates depth relative to grade level(1,333.891 ft)at borehole U850-D1U1-11. with detectable concentrations of BTEX is contained within this volume. The lowest elevation of soil and bedrock with TEPH-diesel concentrations greater that 100 ppm is approximately 1,310 ft (14 ft beneath the excavation). This elevation is approximately 35 ft above the water- bearing zone. Soil samples collected from the excavated soil pile yielded a maximum TEPH-diesel concentration of 16 ppm. The laboratory report mentions that "hydrocarbons present in diesel range may be part of waste oil present in sample." We suspect that these compounds are degradation products of the diesel fuel formed during the five years the soil has been exposed to the elements. Leaching Potential Analysis The potential environmental impact of diesel fuel beneath the tank excavation has been evaluated using the LUFT Field Manual Revision 1 (SWRCB, 1989). In this evaluation, the potential impact of petroleum hydrocarbon contaminants is classified according to contaminant concentrations and geologic characteristics. Sites are also categorized according to whether or not soil and/or ground water is contaminated. Site characterization and remediation requirements are also specified. The 850-DlUl tank excavation falls within LUFT Category 1 because soil contamination, not ground water contamination, is present. To determine if the diesel-containing soil and bedrock beneath the tank excavation could be left in place without impacting underlying ground water, a Leaching Potential Analysis was performed for each rock unit. The analysis is excerpted from the LUFT Field Manual Revision 1 as Appendix G of this report. The analysis scores such site specific characteristics as depth to ground water on a scale of 1 to 10. The 14