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Matthew S. Hayes <br />June 28, 1989 <br />Page 12 <br />8. WECC included the change in the AHR submittal date in this technical <br />revision application and submitted a corrected text page to update the <br />information in the permit. We do not believe that a separate minor <br />revision application which would make the same text change, is warranted <br />for this change. <br />Responses to June 20. 1989. Adequacy Cntestions <br />"A Abandonment Seals" <br />Seal designs for the F seam were provided in the original Mt. Gunnison No. 1 <br />mining and reclamation plan. These plans called for water tight bulkhead type <br />seals to be installed at certain locations in the mine as well as surface portals in <br />the event mine water was found to be of a toxic nature. <br />Non-toxic mine water was planned to be discharged through dewatering pipes <br />installed in standazd non-bulkhead type seals. <br />During original mine permitting, worst case mine inflow rates were utilized due <br />to then unknown conditions. Predicted mine water quality data was available <br />from well data, however, worst case conditions were assumed. <br />Clearly, the history of the F seam since mining was initiated has shown very low <br />localized inflows to the mine workings. These inflows are lower than reasonable <br />predictions and certainly much lower that "worst case" predictions. Inflows <br />which have accumulated and were pumped from the mine in. Sylvester Gulch have <br />met or exceeded NPDES discharge requirements. Even smaller inflows are <br />projected for the E & B seams. It is likely that bulkhead type seals will not be <br />required in the F seam for water quality reasons. It is not appropriate to provide <br />seal designs which will likely require re-design at the end of the life of a <br />particulaz azea or seam, when conditions and water quality are unknown and <br />current predictions indicate water tight bulkhead type seals will likely not be <br />required. <br />