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s <br /> ADDITIONAL GROUNDWATER INVESTIGATION <br /> QUIK STOP No. 132 <br /> 3555 WEST HAMMER LANE <br /> STOCKTON, CALIFORNIA <br /> 1.0 EXECUTIVE SUMMARY <br /> On behalf of Quik Stop Markets, Inc. (Quik Stop), ATC Associates Inc. (ATC) has completed an <br /> additional groundwater investigation for the Quik Stop site located at 3555 West Hammer Lane, <br /> Stockton, California (Figure 1). The purpose of this investigation was to further assess the <br /> vertical and lateral downgradient extent of petroleum hydrocarbons in soil and groundwater at the <br /> site and adjacent area. The results of the investigation are presented in this report. <br /> To further assessg <br /> 1 roundwater conditions beneath the site, ATC completed three soil borings on <br /> July 09, 2000. The soil borings were advanced using a Geoprobe TM sampling rig. Soil and <br /> groundwater samples were obtained at each location. Groundwater samples were collected from <br /> the local upper and lower aquifers. The soil and groundwater samples were analyzed for the <br /> following: total petroleum hydrocarbons as gasoline (TPH-G), benzene, toluene, ethylbenzene, <br /> ' xylenes (BTEX), and fuel oxygenates including tert-butanol, methyl tert-butyl ether (MTBE), di- <br /> isopropyl ether(RIPE), ethyl-tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME). <br /> Groundwater was encountered at depths of 10 to 17 feet below ground surface (bgs) in the upper <br /> aquifer and at depths of 24 to 29 feet bgs in the lower aquifer. TPH-G was detected in <br /> groundwater samples obtained from SB-1 at 10 and 24 feet, from SB-2 at 17 and 29 feet and <br /> from SB-3 at 25 feet bgs. MTBE was also detected in the groundwater samples obtained from <br /> SB-1 at depths 10 and 24 feet bgs, from SB-2 at depths 17 and 29 feet bgs and from SB-3 at 25 <br /> feet bgs. MTBE was below laboratory detection limit in the groundwater sample collected from <br /> soil boring SB-3 at 11 feet bgs. BTEX and other fuel oxygenates, excluding MTBE, were not <br /> present in groundwater samples obtained from SB-1, SB-2 and SB-3. <br /> Based on the results of this investigation, it appears that TPH-G and MTBE have migrated a short <br /> distance generally down gradient on site, in the vicinity of boring SB-1, and off site at low <br /> concentrations, in the vicinity of soil borings SB-2 and SB-3. The maximum TPH-G and MTBE <br /> 1:11a Nr,VsslQU"IOPIQS 132(0003)%EPORTS120001Add1hi10 ,doe ATC Associates Inc, <br />