SITE INFORMATION AND CORRESPONDENCE

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Mr. Sheldon Heckman, c/o Kama E. errigfeld 21 June 2004 River City Petroleum/Former Connell Motor Lift Truck 2211 N. Wilson Way, Stockton -2 - Since 2 -Since contamination has been identified in the 150-foot sand zone,the third monitoring well screened at 145-150 feet bgs is to be installed during Phase One. Also, the Workplan should state that if analytical results confirm petroleum hydrocarbon contamination exists in the Phase One well screened from 250-255 feet,then"...an additional scope will be transmitted to CVRWQCB-CVR Staff for concurrence and approval."for a deeper well. The Workplan proposes the installation of Schedule 40 steel cased 2"diameter monitoring wells, due to anticipated increased thermal load(heating) and weight from neat cement grout precluding the use of polyvinyl chloride (PVC)casing and well screens. As stated in my 6 May 2004 letter,I believe that satisfactory wells can be installed using Schedule 80 PVC and bentonite grout for well construction. Steel cased wells,in addition to being more expensive than PVC wells,can be problematic to sample and expensive to rehabilitate when iron bacteria foul the well screens. I suggest that you reconsider your choice of well casing material. If you choose steel,then you should get State Water Resources Control Board,Underground Storage Tanks(UST)Cleanup Fund approval for the additional cost. Also, if there are problems with biofouling of the steel wells, we would recommend that any rehabilitation costs be paid by you and not be eligible for UST Cleanup Fund reimbursement. Additionally,bentonite grout,if properly emplaced in the boring around PVC wells,would not allow cross-contamination, and would facilitate future well abandonment. The use of a tremie pipe for grout emplacement and centralizers every 20 feet,while holding the well casing string in tension during construction, would aid proper well construction and prevent collapse of a PVC well casing/well screen. It is my understanding that San Joaquin County Environmental Health Department(SJCEHD)permits the use of bentonite grout if it can be demonstrated that the interaction between site contaminants and grout will not prevent proper sealing of the well during installation or cause degradation of the grout after installation of the well. The Workplan proposes use of Sonic Drilling for well installation, stating this drilling method would better isolate the boring from cross-contamination,while minimizing accumulated Investigative Derived Waste(IDW), i.e., contaminated wet sediments and water. Sonic Drilling reportedly dewaters the soil cores prior to removal from the borings. The added cost for Sonic Drilling method is approximate to, or is less than,the cost for drilling and disposal of IDW for hollow stern auger,mud rotary drive casing and air rotary hammer drive casing drilling methods. I concur with the proposal to employ Sonic Drilling for the proposed monitoring wells. I discussed my concerns with site access issues associated with large Sonic Drilling rigs with AGE staff in a phone call on 12 June 2004. It appears that the canopy over the dispenser island will require at least partial removal to allow access to the drill rig mast. It is my understanding that you opposed the entire removal of the canopy,due to the signage attached above the canopy. In order to address site safety concerns,a structural engineer should inspect and assess the condition of the canopy, and provide a stamped recommendation on the proposed partial dismantling of the canopy,prior to its removal. Please provide at least 72 hours prior notice to San Joaquin County staff and myself for fieldwork. You may call me at(916)464-4615 or email me at bartonj6rb5s.swrcb.ca.gov. a.1 James L.Barton,R.G. Engineering Geologist cc: Mr.Mark Owens, State Water Resources Control Board UST Cleanup Fund, Sacramento Mr.Michael Infurna,San Joaquin County Environmental Health Services, Stockton Mr.William Little,Advanced GeoEnvironmental, Stockton