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<br /> August 2001 Quarterly Ground Water Monitoring
<br /> 1645 Cherokee Lane,Stockton,CA
<br /> Hydro-Environmental Technologies,Inc
<br />' 1.0 SITE LOCATION ANIS BACKGROUND
<br />' The subject property is at 1645 Cherokee Lane, Stockton, California, north of the intersection of
<br /> Cherokee Lane and Waterloo Road It is in T2N, R6W of the 1968 (revised 1987) Stockton West,
<br /> California 7 5 minute (1 24,000) Quadrangle The property is approximately 21 feet above mean sea
<br />' level (AMSL)
<br /> The subject property is in an area of mixed light-industrial and commercial buildings, it is part of a
<br />' property used to repair railroad engines by the Central California Traction Company In January 1999,
<br /> Thorpe Oil Company excavated and removed one 6,000-gallon gasoline underground storage tank (UST)
<br /> and one 1,000-gallon diesel UST from the subject property One soil sample, collected from below the
<br />' excavated diesel tank at 9 feet below surface grade (bsg), had 8,000 milligrams per kilogram(mg/kg) total
<br /> petroleum hydrocarbons (TPH) as diesel, 0 33 mg/kg toluene, 0 740 mg/kg ethylbenzene, and 1,800
<br /> mg/kg total xylenes, benzene was below method detection limits
<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, URSGWC conducted a soil bonng/ground water investigation Five borings were drilled
<br /> using direct push (DP) and hollow stem auger The highest TPH as diesel concentrations (at 22,000
<br /> mg/kg) in soil were detected in samples collected from boring B-1 at the 10-foot depth interval
<br /> However, TPH as diesel was detected in soil samples collected from the entire soil boring to ground
<br /> water Concentrations ranged from 6,000 mg/kg (at 15-feet bsg) to 2,000 mg/kg (at 40-feet bsg)
<br /> Ethylbenzene and total xylenes were also detected ranging to 0 011 mg/kg and 0 061 mg/kg, respectively
<br /> at 10 feet bsg
<br />' TPH as diesel was also detected in soil samples collected from boring B-2 (38 mg/kg at 12 feet bsg),
<br /> boring B-4 (27 mg/kg at 10 feet bsg) and boring B-5 (19 mg/kg at 10 feet bsg, 1 1 mg/kg at 20 feet bsg,
<br />' 1,800 mg/kg at 25 feet bsg and 3,200 bsg at 31 feet bsg)
<br /> In their November 4, 1999 letter, the San Joaquin County Public Health Services, Environmental Health
<br />' 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 Lon Duncan, Senior REHS with
<br /> the PHS/EHD, approved the work plan prepared by HETI HETI then installed six DP bonngs
<br /> throughout the subject property Grab ground water samples were obtained from each boring HETI then
<br /> ' installed three ground water monitoring wells to determine ground water flow direction and gradient
<br /> TPH as diesel was detected at 100 parts per billion (ppb) in MW-1 and MW-3 and at 87 ppb in MW-2
<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 TPH as diesel was detected at 60
<br /> ppb in MW-1 and at 89 ppb in MW-3 No detectable concentration of TPH as diesel was found in MW-2
<br /> No detectable concentrations of TPH as gasoline, BTEX, five fuel oxygenates, 1,2-DCA and EDB were
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