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Permit Revision No. 7 -Responses <br />March 7, 1997 <br />Page 5 <br />19. Construction of the ventilation shafts will include installation of a concrete liner and water <br />handling system between the concrete liner and the rock. During construction, any <br />groundwater seepage (projected to be less than 25 gpm) will be directed downward to the <br />shaft bottom and to the active working face. The contractor will remove this water by <br />pumping it to the surface and discharging it into the sediment ditch that captures drainage <br />from the site and will convey it to sediment pond SG-1. <br />Once construction of the shafts is completed, the water handling system behind the concrete <br />liner will collect and convey seepage behind the liner down to the B-Seam where it will be <br />directed to a mine sump. This water will then be handled by the mine dewatering system. <br />This information has been included in Exhibit 69, Project Description. <br />20. The drainage in this area has been redesigned, which eliminates this concern, as all drainage <br />from the construction lay down azea will flow to the sediment ditch and to the sediment <br />pond (SG-1). <br />21. Culverts have been added in the location of DSLY-5 to route water under light-use roads. <br />New and revised SEDCAD designs are enclosed. <br />22. The construction specifications for earthwork require slopes greater than 3H:1 V which will <br />receive embankment fill to be plowed, stepped, or keyed, in compliance with Rule <br />4.03.2(3)(e). Temporary erosion control measures (i.e., straw bales, silt fence, etc.) are also <br />required by the constriction contract specifications. The locations, construction methods, <br />and materials for erosion control and embankment construction are shown on the <br />construction drawings (Exhibit 69). Stability analyses for the embankments (post- <br />construction and post-reclamation) are included in the backup documentation, provided <br />under sepazate cover to Dr. Jim Pendleton. <br />23. Anew material balance (topsoil, earthwork, base coarse, etc.) spreadsheet has been <br />prepared for the entire project and is included as a new table (Table 1) in Exhibit 69. The <br />text in Exhibit 69 for the Transmission/Water Tank road has been revised. The landings and <br />topsoil pile iabels have been added to Map 53B. <br />24. The additional flow from the seeps and springs is considered to be negligible compared to <br />peak flows resulting from a 24-hour storm event and will not have any effect on ditch <br />designs. In addition, ditches are usually constructed larger than the minimum ditch design. <br />The baseflow resulting from water that is encountered during the construction of the <br />ventilation shafts, which is estimated to be 25 gpm or 0.055 cfs, has been incorporated into <br />the SEDCAD model, but has no effect on the ditch design. <br />25. All SEDCAD runs have been revised to include the minimum 0.3 feet of freeboard. The. <br />ditch data chart on Map 54B and Table 44E-1 of Exhibit 66 have been revised accordingly. <br />