Laserfiche WebLink
Woodward-Clyde <br /> V <br /> 4.0 <br /> V <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> V <br /> 4.1 SOIL BORINGS <br /> V <br /> No detectable concentrations of Total Petroleum Hydrocarbons as gasoline and benzene, <br /> toluene, ethylbenzene, total xylenes were found in soil borings B-1 through B-7. Detectable <br /> concentrations of TPH as diesel were found in soil samples collected from soil borings within <br /> and northwest of the former UST excavation. Detectable concentrations of TPH as diesel <br /> -occurred in boring B-3 at depths of 17.5, 25.5, and 35.5 feet as shown by samples B-3-1, <br /> B-3-5, and B-3-7 (Table 2). Detectable concentrations of TPH as diesel in samples B-3-5 <br /> and B-3-7 may be attributed to the existing site condition within the former UST excavation <br /> (See photographs 11 and 12 in May, 1994 WCFS report). <br /> V <br /> The former UST excavation was backfilled after placing a polyethylene sheeting liner within <br /> the excavation. Due to heavy rainfall since the backfilling of the excavation, an unknown <br /> amount of surface water has percolated through the pea gravel backfill material and had <br /> become "perched" within the former UST excavation. Soil boring B-3 acted as a drain outlet <br /> for the perched water. The detectable concentrations of TPH as diesel in samples B-3-5 and <br /> B-3-7 may be attributed to cross contamination of soil boring B-3 from the existing site <br /> V <br /> condition. <br /> Detectable concentrations of TPH as diesel occurred in soil boring B-5 at a depth of 17.5 to <br /> 18 feet bgs as shown by sample B-5-4 (Table 2). Detectable concentrations of TPH as diesel <br /> occurred in boring B-6 at a depth of 16.5 to 17 feet bgs as shown by sample B-6-3. <br /> Detectable concentrations of TPH as diesel in samples B-3-1, B-5-4 and B-6-3 may reflect <br /> the presence of a small zone of petroleum hydrocarbon impacted soil extending from below <br /> the north end of the former UST excavation northwest-ward at an approximate depth of 16.5 <br /> to 18 feet bgs. The TPH as diesel results are below the allowable limit (100 mg/Kg) set <br /> forth in the State of California Tri-Regional Board Staff Recommendations and the Leaking <br /> V <br /> Underground Fuel Tank Guidelines which apply to the KJAX site. <br /> V <br /> 8054/FEMA/XJAXPffiR.RPr/8-24-95 SAC 4-1 <br />