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e <br /> CLEARAOTER ' <br /> r G R O U _P, I N C ' <br /> vacuum flow rate and contaminant concentration extraction, it is necessary to <br /> screen this region separately from the upper sands As the map indicates, the wells ' <br /> will be constructed in the small area between MW-1 and the former pump island ' <br /> Mitchell Drilling Environmental, of Sacramento, will utilize a CME-75 truck <br /> mounted mobil drill rig for the two soil borings Soil samples will be collected from <br /> VW-5, at a depth of 20 and 30 feet with a split spoon sampler driven ahead of the <br /> lead auger The purpose of the proposed vapor wells is not for further site <br /> characterization, and since other intervals in the vicinity of these wells have been <br /> previously sampled and characterized, this limited soil sampling is recommended <br /> Drum Management <br /> In addition there are 18 55-gallon drums at the subject site which contain purge <br /> water from MW-1, 2, 3, and 4 Per our discussion, Clearwater will empty drums <br /> from MW-1, 2, and 3 _directly_to the ground Table_2, "Summary of _Laboratory <br /> . Analyses - Groundwater" from Resna's corrective action plan dated July 6, 1994, <br /> ` shows almost all previous samples from these wells to be below the method <br /> detection limit Only one sample, dated October 18, 1993, from MW-3 tested <br /> positive, at 86 ppb TPHd All subsequent samples from MW-3 were non detect for <br /> petroleum hydrocarbons Given this information, and my discussion with you, <br /> Clearwater will empty those drums directly to the ground Drums from MW-4 and <br /> those with no labels, wifl be discharged to the sanitary sewer, pending City of <br /> Escalon approval <br /> Quarterly Monitoring <br /> Clearwater concurs with the PHS/EHD response to Resna's request for eliminating <br /> monitoring/sampling of wells at this site It is apparent, however, that a <br /> modification to the current program is in order Therefore, Clearwater recommends <br /> that all wells be monitored quarterly for water table elevation, but that samples only <br /> be collected from 'MW-1 The other wells are upgradient from and outside of the <br /> impacted area Samples from these wells have been free of hydrocarbon <br /> , <br /> contamination since they were installed <br /> ' r <br /> r <br />