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. SUMMARY OF ENVIRONMENTAL ACTIVITIES JACKPOT FOOD MART, 1434 WEST YOSEMITE AVENUE, MANTECA, CALIFORNIA PROPERTY 04-167 Update current as of February 13, 1995 Underground Storage Tank Removal - September 1991 On September 19, 1991, a 12,000 gallon tank formerly containing unleaded gasoline, an 8,000 gallon tank formerly containing regular gasoline, and a 6,000 gallon tank formerly containing premium unleaded gasoline were removed from the subject property The tank removal was performed by Post Tank and consultant services were provided by Canonie Environmental Upon removal, the tanks appeared to be in good condition and it did not appear to have leaked The tanks were last precision tested on December 7, 1990 and were found to be tight Although visual inspection of the tank excavation did not reveal any areas of obvious contamination, a hydrocarbon odor was noticeable in the samples collected from the northwest corner of the excavation and beneath the north pump island None of the other samples appeared to be contaminated Groundwater was not encountered to a depth of 14 5 feet At the direction of a representative of the San Joaquin County Public Health Services Environmental Health Division (PHS/EHD), soil samples were collected from the tank excavation and from beneath each of the former pump islands All samples were submitted to a certified laboratory and analyzed for total petroleum hydrocarbons (TPH) as gasoline by EPA Method 8015 and benzene, toluene, ethylbenzene, and xylenes (BTEX) by EPA Method 8020 Samples collected in the vicinity of the leaded gasoline tank and pump islands were also analyzed for ethylene dibromide and total lead Analyses revealed TPH in the samples collected from beneath the west ends of the 12,000 gallon tank and 8,000 gallon tank at concentrations of 460 ppm and 1 ppm, respectively The sample collected from beneath the north pump island indicated 13,000 ppm TPH None of the other samples contained detectable concentrations of TPH or BTEX During the removal of the tanks, approximately 300 cubic yards of hydrocarbon-impacted fill material were removed from the excavation and placed on plastic sheeting on the south edge of the property On March 15, 1992, the soil was transported to Callahan Treatment Facility in Red Bluff, California for treatment by aeration and proper disposal A copy of Canome Environmental's "Preliminary Investigation Report" was forwarded to the PHS/EHD and California Regional Water Quality Control Board (CRWQCB) on December 17, 1991 Preliminary Investigation - August 1992 Based on the results of the samples collected during the tank removal, a site assessment was initiated in August 1992 to determine the extent of hydrocarbon-impacted soils at the above-referenced site Because previous site work identified the presence of groundwater at depths of less than 12 feet, a groundwater investigation was also required Prior to the implementation of field activities, Canonie's workplan dated July 24, 1992 was submitted to the PHS/EHD and CRWQCB Authorization to proceed with the proposed work was received from the PHS/EHD on August 4, 1992 On August 27, 1992, a soil vapor survey was performed to assist in determining the vertical and lateral extent of contamination at the subject site A pneumatic hammer was utilized to drive 9 soil vapor probes to depths of up to 15 feet in the vicinity of the former tanks Vacuum pumps and charcoal tubes were used to collect vapor samples from each probe at various depths Immediately after collection, each sample was submitted to an onsite mobile lab where it was extracted and injected into a gas chromatograph f