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4- 26 November 1996 <br /> TRC MEETING <br /> 305 S.HUTCHINS,LODI,SAN JOAQUIN COUNTY <br /> 4 <br /> COMMENTS <br /> 1 A majority of the TRC committee voted that no further action at the site. Regional <br /> Board staff did not cOncIz- <br /> 2. <br /> Itis questionable whether the MTBE is from this site,bec 1 ause the station stopped selling fuel in <br /> MTBE may be from an upgradient <br /> MTBE was not approved for use until 1979. The <br /> 1977 and M <br /> source, <br /> 3. The chloroform,TCE,PCE,and 1,2-DCE are part of a larger dry cleaner solvent plume in the City <br /> of Lodi. <br /> 44 The distribution of soil contamination indicates that there were three possible sources,the old <br /> service station under the current building,and the more recent pqMT island and tank pit <br /> - 1M: <br /> The investigation to-datedidnot provide adequate'data to provethatTP11 gi TPHdBAnd <br /> DCA contamination did not come from this site. If ground water contamination did emanate from <br /> this site,then the plume is commingled with the that from;the Bokides,site and the Lodi solvent <br /> plume. from this There al an <br /> A. T?Hg and BTEX groundwater contamination may be coming om s site is so <br /> upgradient site(Bokides)that also hada gasoline release. Either or both of the sites may be <br /> contributing to the TPHg groundwater contamination. <br /> B. Reportedly diesel was never sold at this site, therefore,diesel contamination may be from off- <br /> site. However,it is possible that the diesel is actually weathered gasoline;no chrornatograms <br /> have been provided and the laboratory reports were not consistent. <br /> C. There are several possible sources of 1,2-.DCA contamination. <br /> a. The site itself,because DCA is a component of gasoline; <br /> b. The upgradient site,also because DCA is a cor iponent of gasoline. <br /> C. The solvent plume,because DCA is a breakdoiAm product of TGE in the presence of <br /> gasoline and anoxic conditions;and <br /> d. Any combination of the above. <br /> 6. Reportedly,soil samples from two downgradient borings Were tested for DCA and came up ND. <br /> However,our file does not contain these sample results. It is my understanding that the soil <br /> " <br /> samples were collected at or just above the water table 1 t is unclear how ground water samples <br /> 1- -4heborings-could-contain- le samples-do-mot:c-=-- -. <br /> collected rom DCA-while the soil <br /> 7. Without additional DCA analyses from soil.samples, we&mnot rule out the possibility that the <br /> Togo's site is a source. 5 <br /> S. Between June 1993 and March 1994,,limited vapor extraction was conducted using VW-1 in the <br /> tank pit,and removing approximately 3300 lbs of fuel hydrocarbons. The other 5 vapor extraction <br /> wells were not used. Therefore,soil contamination undei the building near the older service <br /> station,and near the more recent pump islands has not been:,mmediated. <br /> 9A The confirmation borings near the vapor extraction well were drilledto only 25 feet,1herefore, <br /> whether contamination remains below 25 feet, is not known. <br /> If all 6 vapor extraction wells had been used for vapor extraction,it is Rely that soil <br /> contamination would have been reduced and would no lo 3 nizer provide a threat of any kind to water <br /> quality. <br /> 1L Because solvent and MTBE plumes are under the site,monitor well destruction is counter <br /> �productive to problem investigation and resolution. <br />