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<br /> r' 7'ItC MEETING
<br /> -3- ;.
<br /> 305 S.HUTCHINs,LODI;SAN JOAQ COUNTY 26 November 1996 .
<br /> INVESTIGATION SLM04ARY
<br /> The subsurface consists of interbedded layers of sand, silt,'and clay,with a predominance of sand.
<br /> Depth to water has varied from S l to 57 feet. The direction of groundwater flow varies between east,
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<br /> southeast,and southwest. Two groundwater production wells arc located within J mi1e.. Old.Well No.
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<br /> 3.is 1600 feet northeast of1he site and has not been in use since 11989 due to PCE cantaminataon.
<br /> Replacement Nell 3R was-installed 1100 feet to the northwest of Old Well No.3 and has;no wader
<br /> quality problemS,
<br /> A total of26 borings were drilled duri4 the site investigation,and 5 monitoring wells and 6 vapor
<br /> extract`c�n wells were installed. Two of the vapor extraction well
<br /> ys are slant borings under the existing
<br /> ":P* —^r '' .. .+i.bii yY .-HT.4 �4Y,nr `M- }
<br /> building, dr,Tled tot�vard.the assumed lvcatitSn of the foriner staticlit°liuild ng. MV'-1 MW 2;and lyM4.
<br /> are on site,MW . is cross gradient and ofd-site to the east across Hutchins.Stet,end ItiI U-S is
<br /> upgradien, and off-=site to the north across Lodi Avenue.
<br /> In ground water at the s>rte;T 1 TPHg,BTEY,MTBE,chlorofop, 1,2-I?Cl✓,TCE,PCE;and
<br /> 1,2-DCA were.detected; `. ..
<br /> 1. TPHg,TPHd, and BTEX have been detected sporadically iii the three on-site axed two off--site
<br /> wells. In the past,u :to 910 b TPHg,,1200 b TPHd 120 b benne 240 b toluene 29
<br /> P P pFPP ,� FF � ppb ,
<br /> ppb ethylbenzene,and 30 ppb xylene were found on site. IAJuly 1996,tarp to 260 ppb TPHg,71
<br /> ppb TPHd, and low levels of ethylbenzene and xylene were detected. In July 1996,the off--site
<br /> crussgradient well MW4 had no detectable fuel hydrocarbons and the upgradient well MW-5
<br /> contained 290 ppb TPHg,62 ppb TPHd, 17 ppb benzene,ar`d detectable-concentrations of TEX.
<br /> 2. MTBE has been detected consistently in on-site wellsW'l and MW-3,and the off-site well
<br /> MW-5 and sporadically in MW-2, on-site. MTBE has not been detected in the off-site well MW-4
<br /> On-site,NME has been as high as 920 ppb in MW-1. In MW-5,off-site,MTBE has been as high j
<br /> as 720 ppb. In July 1996,the wells had 300 ppb and 190 ppb respectively.
<br /> Solvents including 1,2-DCA have been detected sporadically in all wells but MW-4: Only PCE: 1
<br /> has-been detected,sporadically,in MW-4. DCA has been as high as 86 ppb in MW-1 and
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<br /> A layer of containinated soil exists between:15 and.43 feet:below;the:surface,.apparently coinciding with
<br /> former,levels of the shallow water tables V0)3j&5,
<br /> 1. Near the old service station,up to 6700 ppm TP was detected at 25 feet,
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<br /> 2. Near the more recent
<br /> pump islands,up to 2800:. TPHg was detected at 42.5...feet;and:
<br /> 3t1 Near the more recent tank.pit,up to 11,000, ,TPHg was detected at.25 feet and mtuch lower r
<br /> ' levels of toluene were detected to ground Z?eo ?+` *VM1Z rs17'b -04
<br /> 4: TP Id was also detected in soil samples between 15 and 35 feet;atup t©_2400 ppm near the recent
<br /> PUMP islands and tank pit. i; ;
<br /> S. Below.01ae tthe highest levels of contamit7ation were 26 ppm TPHg at 45 fit and 12 ppm
<br /> TPHmo;(weathered gasoline or... iesel?}at 53 feet,both collected near the pump islands:
<br /> MTBE was:not detected in.any bil samples. f.
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<br /> According to the infaxrnahon xn aur files,none of the soil samples were tested for DCA.' j
<br /> 8., Sail samples were-not-Analyzed for the other solvents,;
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