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CVA <br /> 1117 Lone Palm Avenue, Suite B <br /> Modesto, CA 95351 <br /> http/Iwww atcassociates corn <br /> %TC209 579 2221 <br /> gssocigrsEs i Kc <br /> Fax 209 579 2225 <br /> May 17, 2004f'ECOV <br /> ED <br /> 54 22493 0001 <br /> Mr Jeff Wong MAY 1 G 2005 <br /> San Joaquin County ENVIRONMENT HEALTH <br /> Environmental Health Department PERMIT/SERVICES <br /> 304 East Weber Street, Third Floor <br /> Stockton, California 95202-2708 <br /> Subject Monitoring Report Second Quarter 2004, Eggiman Property, 1112 East Harding Way, <br /> Stockton, California <br /> Dear Mr Wong <br /> This report presents the results of the second quarter 2004groundwater monitoring and sampling <br /> performed on April 9, 2004, by ATC Associates Inc (ATC) at the site located at 1112 East Harding <br /> Way, Stockton, California (Figure 1) Monitoring was performed to determine groundwater flow <br /> direction and the hydraulic gradient in the uppermost aquifer Sampling was performed to monitor <br /> the petroleum hydrocarbons in the groundwater at the site <br /> BACKGROUND <br /> In April 1987, SEMCO removed and disposed of two 1,000-gallon regular gasoline underground i <br /> storage tanks (USTs), associated piping, and fuel dispenser from the locations shown on Figure 2 A <br /> soil sample was collected from beneath the end of each tank at approximately 17 feet below ground <br /> surface (bgs) Analytical testing indicated the collected samples contained detectable concentrations <br /> of petroleum hydrocarbon constituents The excavation was subsequently backfilled to the ground <br /> surface <br /> On July 24, 1997, to investigate the extent of residual soil contamination at the site, a total of six soil <br /> borings were advanced to depths ranging from approximately 16 to 31 feet bgs Detectable <br /> concentrations of total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as <br /> diesel (TPHd), and benzene, toluene, ethylbenzene, and xylenes (BTEX) were observed in soil <br /> samples collected from the site The distribution of petroleum constituents beneath the site has been <br /> essentially defined and appears to be limited laterally to the immediate vicinity of the former tank pit <br /> The highest concentrations were reported between 10 and 20 feet bgs and generally attenuate rapidly <br /> with depth Only low concentrations of toluene (0 064 mg/kg) and xylenes (0 012 mg/kg) were <br /> detected at approximately 30 feet bgs in one boring, the maximum depth explored Attempts were <br /> made to further advance the Geoprobe8' unit in several of the borings, however probe refusal was <br /> encountered at depths ranging from approximately 16 to 30 feet bgs due to the hardness of the <br /> formation The results of the subsurface investigation were summarized in Smith Technology's <br /> Summary Report, Subsurface Investigation, dated December 22, 1997 <br /> • In April I999, at the request of PHS/EHD, ATC completed a receptor survey for the subject property <br /> ATC reviewed PHS/EHD groundwater well construction logs, Department of Water Resources <br /> s\environmenWk22493AWROWNTAL, GEOTECHNICAL AND MATERIALS PROFESSIONALS <br />