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7 }. <br /> 305 Hutchins, Lodi page 2 <br /> Mike Harper <br /> 3 <br /> active gas station(Bokides))did detect Benzene for this date at X17 ug/l, Additionally, MTBE was <br /> detected in MW-5 for the same date 90 00 ug/I as well as DCA,-IDCE, TCE,and PCE <br /> it <br /> It has been the contentionof the consultingfirm for the FDIC that constituents of concern detected in <br /> Toga's wells have been directly related to the Sokides site. MTBE, Benzene,,and DCA <br /> concentration levels have shown correlated patterns when the groundwatetanalyses have been. ' <br /> evaluated: <br /> r <br /> MTBE•iso-conceritra on maps have shown anincreasing concentration pattern as if groundwater <br /> flows southerly onto.and through the Togo's site. With this in mind, PHS-EHD placed the Brikides <br /> site into the SW. -RCB L.ocai Oversight Program (Lf3P)for investigation tf their suspected <br /> unauthorized:release from the&t located on their site, { <br /> PHS-EHD concluded!n c.offispondenee January9, ' <br /> 1996 that the soil 5ti11 in piece on the Tago's site <br /> at 25 feet below ground surface(`bgs)contained TPH-G concentrations as high as 6700 mg/kg in <br /> one area and.:600.0 mg/kg inano#her area and:may contributing to the groundwater degradatipn. <br /> Since a precious vapor extract ion effort from VW-1 has proven to be effedti!ve.at reducing 1'i,f�00. <br /> M g/kg of TPWG-soil contamination at boring "E811-25"to non detect, PHS-EHD requlred additional <br /> vapor extraction wells artd a 6111 vapor extraction test#o be conducted at the other areas of concern. <br /> A vapor extraction:test conducted.on the newly installed vapor wells also in diCated.positive results. <br /> PHS-EHD Waa preparing to approve this:remedia�l activity when the Lawrence;l..ivermore study was <br /> released and the SWRCB recommended LOP agencies re-evaluate sites based dh:a"low:t1SIC <br /> criteria. Based on a recepto,survey,"the levels of constituents of concern at the time, the real <br /> possibility that an up-gratilen#source existed. and that no significant Benzene contamination was <br /> noted in the ser!still on-site, OH Hb concluded that vapor extiaction may not be the most cost:. <br /> effective method when compared to natural attenuation over time. <br /> CVRWQCB recommendaboAs include soil sampling for 1,,2 DCA1 as well as TPP 0,TPH=D,TPH- <br /> Ml's, BTElC,and MTBE in."snits above the 1979 water level". Additional recommendations from the <br /> CVRWQCB include 1 no 1,2`•DCA is detected in soil samples abeve the 1979 water level;we <br /> (CVRWQCB)wiil:concurwkh1 site closure.,.," This statement confirms that the CVRWQC8 does not <br /> consider that the primary constituents`0 gasoline require further investigation and remediation: The. <br /> only constituent the CVRWQCB lis concerned with is 1,2 DCA. The TRC discussed the existence <br /> and levels of11,2 IBCA in the groundwater extensively and concluded that 1,2 DCA is associated <br /> with the degradation of PCE and TCE as well as a past additive used in gasoline. <br /> Even if 1,2 DCA,is found in tllle soil at this:site, the source of the 1,2 DCAJn-the groundwater may be <br /> from the breakdown of the PCE and TCE. In addition,the only drinking water wells within 2000 feet <br /> of this site are up-gradient a4d it is not anticipated that they will be impacted by a release from this <br /> site. Remediation;of the 1,2 DCA in the groundwater does not appear to be cost-effective,since the. <br /> levels in the groundwater at this time are inconsistent. <br /> jl <br /> i <br /> 3 ' <br /> •1 <br />