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• Previous estimates were higher because they included assumptions that faults would contribute significant inflows. <br />The mine has crossed a number of faults, including two significant fault zones. Fault inflows have never exceeded <br />25 gpm in the short-term (one to two weeks), and have never exceeded 10 gpm average over a year. <br />The accuracy of these calculations depends on the quality of the input data. The most important input parameter is <br />hydraulic conductivity. The results of the calculations depend, to a lazge degree, on the validity of the hydraulic <br />conductivity value for a large section of the aquifer. <br />Limitations of this method of calculation for a large mine with variable hydrogeologic conditions due to the <br />tentacular character of the sandstone is in defining an average hydraulic conductivity representing all sections of the <br />mine. Results of the calculations, therefore, express the general trends in inflow and the values should be <br />considered very approxirnate. The calculated values are not specific for certain smaller sections of the mine and <br />express an average inflow per year. <br />(cl For underground minin¢ activities, the application shall contain a detailed description, with <br />appropriate drawings, of permanent entry seals and down-slope barriers designed to ensure stability under <br />anticipated hvdraulic heads develoQed while promotinP mine inundation after mine closure for the proposed permit <br />area and adjacent area. <br />RESPONSE <br />The Foidel Creek Mine will not require permanent entry seals to prevent drainage after mine closure. The <br />underground mine is designed to drain away from the portal entries during and after operations. Mine inundation <br />• will be promoted after mine closure by allowing the entries to flood with groundwater inflow. The entries will be <br />permanently buried after mine closure by backfilling the underground portal area as required under Rules 4.07 and <br />4.14. <br />(4) Protection of public parks and historic places. For andpublicly owner park or place listed on the <br />National Register of Historic Places that may be adversely affected by the proposed operation, each <br />RESPONSE <br />No public parks are located within the proposed permit area or adjacent areas or the Fish Creek Tipple permit area. <br />Consequently, the planned underground mine and associated operations wilt not affect any public parks. The <br />planned underground operations will not affect any places included on or eligible for listing in the National Register <br />of Historic Places, as described under Rule 2.04.4 <br /> <br />PR 99-OS 2.05-171.13 8/27/99 <br />