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[ tx <br /> Atlantic Richfield Company 2 <br /> ARCO 434 501 Kettleman Cane,Lodi CA December 11,2000 <br /> A SECOR technician noted an oily sheen prior to purging the well Field procedures are <br /> presented in Attachment B Groundwater extraction field data sheets are included as <br /> Attachment C <br /> Groundwater Sampling and Analysis <br /> Well W-9 was sampled on November 1, 2000 to determine if batch extraction was <br /> effective in reducing hydrocarbon concentrations in this well Field and laboratory <br /> procedures are presented in Attachment B Groundwater sampling field data sheets are <br /> included in Attachment C, and certified analytical reports and chain-of-custody <br /> documentation are presented in Attachment D <br /> Samples were analyzed for TPHg by EPA Method 8015, benzene, toluene, <br /> ethylbenzene, xylenes (BTEX), and MtBE by EPA Method 8020, Oil and Grease by <br /> EPA Method 413 1,Total Lead by EPA Method 6010A, and chlorinated hydrocarbons <br /> by EPA Method 624 <br /> The above analytes were not detected in the sample from well W-9 <br /> Concentrations in well W-9 before and after batch extraction are shown below <br /> W-9 <br /> TPHg(ppb) Benzene(ppb) Ott and Grease(mg/l) MtBE(ppb) <br /> . 9/5100 113 <0 50 430 <2 0 <br /> 11/1100 <50 <0 50 <5 0 <2 5 <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> Based on analytical groundwater monitonng data from November 1, 2000, groundwater <br /> batch extraction appears to have been effective in reducing both TPHg and Oil and <br /> Grease concentrations in well W-9 to below standard detection limits <br /> SECOR, on behalf of ARCO, recommends the continued analysis of Oil and Grease in <br /> well W-9 for one additional groundwater monitoring event (4th Q 2000)to verify the <br /> above data <br /> i <br /> 077 42007 001/batchext[acuon doe <br />