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<br /> EXECUTIVE SUMMARY
<br />' The subject property is at 1645 Cherokee Lane, Stockton, California, north of the intersection of
<br /> Cherokee Lane and Waterloo Road The subject property is in an area of nuxed light-industrial and
<br />' commercial buildings, it is part of a property used to repair railroad engines by the Central California
<br /> Traction Company In January 1999, Thorpe Oil Company excavated and removed one 6,000-gallon
<br /> gasoline underground storage tank (UST) and one 1,000-gallon diesel UST from the subject property
<br />' One soil sample, collected from below the excavated diesel tank at 9 feet below surface grade (bsg), had
<br /> 8,000 milligrams per kilogram (mg/kg) total petroleum hydrocarbons (TPH) as diesel, 0 33 mg/kg
<br /> toluene, 0 740 mg/kg ethylbenzene, and 1,800 mg/kg total xylenes, benzene was below method detection
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<br /> Hydro-Environmental Technologies, Incorporated (HETI) reviewed the September 1999 URS Greiner
<br /> Woodward Clyde (URSGWC) final report UST Investigation, 1645 Cherokee Lane, Stockton, CA In
<br />' August 1999, URS Greiner Woodward Clyde (URSGWC) conducted a soil boring/ground water
<br /> investigation Five borings were drilled using direct push (DP) and hollow stem auger The highest TPH
<br /> as diesel concentrations (at 22,000 mg/kg) in soil were detected in samples collected from boring B-1 at
<br />' the 10-foot depth interval However, TPH as diesel was detected in soil samples collected from the entire
<br /> soil boring to ground water Concentrations ranged from 6,000 mg/kg (at 15-feet bsg) to 2,000 mg/kg (at
<br /> 40-feet bsg) Ethylbenzene and total xylenes were also detected ranging to 0 011 mg/kg and 0 061 mg/kg,
<br />' respectively at 10 feet bsg
<br /> In their November 4, 1999 letter, the San Joaquin County Public Health Services, Environmental Health
<br /> M Division (PHS/EHD) requested a further investigation to determine the lateral and vertical extent of the
<br /> petroleum contamination at the subject property On June 15, 2000, Ms Lori Duncan, Senior REHS with
<br /> the PHS/EHD, approved the work plan prepared by HETI HETI then installed six DP borings
<br />' throughout the subject property Grab ground water samples were obtained from each boring No
<br /> detectable concentrations of TPH as gasoline, TPH as diesel, benzene, toluene, ethylbenzene and total
<br /> xylenes (BTEX), or the five fuel oxygenates were found in the 46 soil samples and six grab ground water
<br />' samples submitted for analysis
<br /> HETI then installed three ground water monitoring wells to sample ground water and to determine ground
<br />' water flow direction and gradient TPH as diesel was detected in all three ground water monitoring wells
<br /> No detectable concentrations of TPH as gasoline, BTEX, or the five fuel oxygenates, 1,2-dichloroethane
<br /> (1,2-DCA) and 1,2-dibromoethane(EDB) were found in the ground water samples submitted for analysis
<br /> HETI then began quarterly ground water monitoring at the subject site During the first quarter of ground
<br /> water monitoring, TPH as diesel was detected in MW-1 and MW-3 No detectable concentration of TPH
<br />' as diesel was found in MW-2 No detectable concentrations of TPH as gasoline, BTEX, or the five fuel
<br /> oxygenates, 1,2-DCA and EDB were found in the ground water samples submitted for analysis Because
<br /> no TPH as gasoline was detected in the initial and first quarter ground water monitoring event, PHS/EHD
<br />' removed the five fuel oxygenates, 1,2-DCA and EDB from the ground water monitoring rounds
<br /> During the August sampling round, MW-2 and MW-3 were dry and no samples were collected A sample
<br />' was collected from MW-1, however, the laboratory's quality control failed to produce results within
<br /> acceptable detection ranges During the current sampling round, all of the ground water monitoring wells
<br /> were dry (MW-1 to MW-4) Groundwater monitoring will continue for one additional quarter
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