COMPLIANCE INFO_1999 - Laserfiche WebLink

Home Browse Search

UST Closure Report Sharpe Defense Distribution Region West Lathrop,California Page 25 The sludge and rinsate from triple rinsing the tanks and overlying piping were transported by Delta Oilfield Services to Chico Drain Oil Services for treatment and disposal. The eight tanks were inerted with `dry ice' and transported by Trident Truck Lines from the site on December 23 and 24, 1998 to Ecological Control Industries' (ECI) licensed treatment and disposal facility in Richmond, California. The product and vapor return piping were triple rinsed then excavated and removed along with three ground-level, and six overhead fuel dispensers after demolishing and removing two concrete dispenser islands and their drive aprons. The rinsate was transported by American Valley Waste Oil to Industrial Service Oil Company's treatment and disposal facility in Los Angeles on February 5, 1999. The piping and dispensers were transported by Ecological Control Industries to their treatment/disposal facility in Richmond, CA on February 9. About 800 cubic yards of silty sand were removed from the UST excavation. It had no obvious petroleum product odor or discoloration. A lithologic log of a pre-UST installation borehole suggests that the original UST excavation was backfilled with native sediments, that is, with silty sand, clayey sand and sandy clay. The initial stockpiles of excavated soil along the western and southern sides of the excavation were consolidated into two stockpiles (SPA and SPB)just west of the north and south ends of the excavation. The soil in the two stockpiles were mixed, aerated and moved to the south side of 3`d Avenue (stockpile SPD) on February 3 and 10 after approval was obtained by the Base Environmental Department from the San Joaquin Valley Unified Air Pollution Control District to aerate the soil. The 60 cubic yards of soil excavated from the product and vapor return pipe trenches were stockpiled (in SPC) just south of the dispenser island sites on February 4. The stockpile was moved, upon direction from the U.S. Army Corps of Engineers, to a site about 400 feet southeast of the UST excavation. Technicians from Neil O. Anderson & Associates and later, GeoAnalytical Laboratories, Inc. collected 123 soil samples and 8 groundwater samples from the UST excavation and stockpiled soil. The samples were collected under the direction and guidance of representatives of the San Joaquin County Environmental Health Board, then later, the Central Valley Regional Water Quality Board. A total of 78 soil samples and one groundwater sample were analyzed at North State Environmental and GeoAnalytical Laboratories for TPH-G, TPH-D, BETX, oxygenates and total lead. Nineteen soil samples were collected from the floor of the UST excavation. They included three samples from beneath the concrete tie-down pad obtained by boring through the concrete in the north, central and southern parts of the excavation, and 16 from the margins of the pads. Concentrations of MTBE of 8 to 1000 µg/kg were detected in the samples from the west and southeast sides, and beneath the northern part, of the UST pads. Benzene concentrations ranged up to 100 mg/kg in the three samples in which MTBE was detected. The concentration of TPH- -D was greater than the method detection limit in only three of the samples, the highest was 200 mg/kg. Lead concentrations ranged from less than 1.0 mg/kg to 22 mg/kg. The groundwater sample collected from the floor of the UST excavation after purging about 350 gallons of water from it, contained a very high concentration of MTBE (450 µg/kg) and trace to minor N:\PROJECTS\3546\Reports\3546 UST Closure Report DraR.doc March 24,1999