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<br />Although EPA does not believe that additional testing requirements are needed in <br />the Permit as a result of these comments, a change will be made as a means of clarifying the <br />submittal requirements. The Permit (Section A. 5.) will be clarified to require submittal of <br />any pH, SC or other water quality testing data, if collected, during drilling of the wells. <br />These data must be submitted along with the other completion information prior to <br />issuance of the authorization to inject approval. <br />Comment 19: The section on "iniection interval" PLage 15. Draft Permitl does not soecifv an <br />interval but merely savs. "the injection zone is approximately 150' to 800' below Dissolution <br />Surface." Specific limits should be placed on the injection interval. <br />Response: The injection interval was defined in the Permit in a manner to provide some <br />flexibility to the operator as to where to mine in the saline zone, depending on the availability of <br />the recoverable nahcolite resources within the 150 to 800 foot range below the Dissolution <br />Surface. It is antisipated that the presence of halite beds which overlie the nahcolite zone in much <br />of the lease may , in fact, increase the thickness of the roof cap significantly. Additionally, the <br />nahcolite zone may extend below the 800 foot interval. The mining plan does, however, indicate <br />that there will be a minimum 150 foot buffer zone from the top of the cavity to the Dissolution <br />Surface. <br />EPA has modified the Permit to require a minimum of 150 feet of cap rock between <br />the top of the cavity and the Dissolution Surface. The bottom of the injection interval will <br />be approximately 800 feet below the Dissolution Surface. <br />Comment 20: The well Failure Response Plan. To date, these plans have not been made <br />available to the public. <br />Response: Solution mining well-operating information was provided to EPA in the Pemut <br />Application. These data included normal values for operating parameters and described the <br />relationship between operating parameters. It also presented situations that may be indicative of a <br />cavity leak or an instrumentation failure and provided descriptions of response measures. <br />Additional monitoring and response information was provided in Section 5.0 of the Ground- <br />Water and Surface Water Monitoring Plan, which covers process monitoring. This information <br />provides the basis for the mechanical integrity testing which is required by the Permit. This <br />information was available for public review and comment. <br />It is EPA's determination that the solution mining well-process monitoring proposed in the <br />monitoring plan would detect a cavity leak and is adequate for demonstrating that the well has <br />mechanical integrity. The operator will install equipment of adequate accuracy at the wellheads <br />and elsewhere in the field to measure the following parameters at 10-minute intervals: 1) <br />injection pressure; 2) injection fluid temperature; 3) injection fluid specific gravity; 4) injection <br />fluid flow rate; 5) production pressure; 6) production fluid temperature; 7) production fluid <br />specific gravity; 8) production fluid flow rate; and 9) nitrogen gas cap pressure. Values for these <br />pazameters will be automatically reported to a master control system. Any reported values that <br />differ significantly from normal operating conditions will be immediately investigated by American <br />35 <br />