SITE INFORMATION AND CORRESPONDENCE

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Mr. Joe Hofbauer • - 3 - • 2 February 2007 Pioneer Americas LLC supply, the well's horizontal and vertical location should be surveyed, the well should be configured in a way that groundwater samples can be collected utilizing standard monitoring well sampling methods, and the well casing should be configured so that depth to the groundwater surface can be measured. The Regional Water Board requests Pioneer to submit a letter to the Regional Water Board documenting these procedures. If these procedures are not practical or possible, Pioneer must install a monitoring well on the Facility property and screen it within the Lower Horizon. 3. At least one Lower Horizon monitor well is necessary at a location between Defense Logistics Agency wells LM177B and LM151B, and water supply well AP-2. A suitable well location may be available next to a railroad track access road, approximately 40 to 60 feet northeast of the track's intersection with Banta Road. This location should be an adequate alternative to locations within the agricultural properties north of the Facility. 4. In July 2005, Pioneer installed two additional water supply wells at the Facility: Banta #1 and Banta #2. These wells were installed to replace water supply wells AP-1 and AP-2, installed in 1975. The Well Completion Reports, prepared by Calwater Drilling Co., Inc., are included in Appendix D of the Draft Cleanup Plan. According to these reports, the soil boring for Banta #1 was 10 inches in diameter and drilled to a depth of 280 feet bgs. The soil boring for Banta #2 was also 10 inches in diameter, but drilled to only 200 feet bgs. Both wells were constructed of 8 inch diameter plastic casing, screened from 90 to 130 feet bgs, and "8X16 gravel" filter packs from 70 to 130 feet bgs. The Well Completion Reports do not indicate how each boring was completed below 130 feet bgs. Pioneer should submit a letter or revised well completion reports that describe how the borings were completed below 130 feet. Also, please provide specifications for the filter pack. 5. The Regional Water Board has included groundwater sampling of Facility water supply wells AP-1, Banta #1 , and Banta #2 in the MRP. Also, monthly compilation of gallons pumped from each of these three wells has been included in the MRP. In addition, we have added the four private domestic water supply wells currently sampled by Pioneer to the MRP. Additional Comments 6. The Draft Cleanup Plan should not be finalized until the extent of the COC plume in the Lower Horizon has been characterized. 7. As of early 2005, water from the Pombo private water supply well is again being used. In lieu of wellhead treatment, Pioneer is supplying the Pombo residence with drinking water through a private contractor. As specified in the Feasibility Study, Pioneer must begin wellhead treatment of the Pombo well as soon as possible.