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<br />J.E. Stover & Associates -21- May 31, 1996 <br />Bowie No. 2 Mine <br />69. Comments included above under section 2.05.3(2) pertain to <br />the potential exposure of the proposed coal mine waste and <br />non-coal processing waste facilities to impacts from the <br />geological hazards identified on the permit area. <br />70. The material balance section in volume 4 is not clear with <br />respect to topsoil salvage and availability for reclamation. <br />Of the four foot cover requirement, how much will be general <br />coverfill and how much will be topsoil. From reviewing the <br />baseline soils report, it would appear that at least two <br />feet of the final cover will consist of topsoil. Please <br />expand the discussion in this section to clearly explain the <br />salvage and redistribution related to both topsoil and other <br />cover material. <br />The following comments follow the format in Volume IV. <br />Volume IV - 'Coal Mine Waste Bank Final Design for <br />the Bowie No. 2 Mine' <br />2.1 Surface Conditions <br />WESTEC observes that no surficial springs or signs of ephemeral <br />streams were noted within the footprint of the proposed waste <br />pile in September of 1995. Because September is near the annual <br />ground water low stand, BRL should reexamine the footprint of the <br />proposed pile at the normal wet period of the year, during May or <br />June. <br />4.1.4 Runoff Control Ditches <br />WESTEC states; "The 35-inch maximum riprap size recommended for <br />these side ditches is large, compared to ditch size and flow <br />depth. This requirement provides for the stability of the <br />material under loads transferred by flowing water and for mass <br />stability of the riprap itself. It is found that placing riprap <br />this size is not practical, it is suggested that the D50 material <br />size, 24 inches, be placed and secured using grout." <br />If the riprap is to be placed and secured with grout, rather than <br />with the traditional gradational filter blanket, a specification <br />and drawings for the riprap grading and grout placement shall be <br />included within the permit documentation. Further, since a <br />grouted pan cannot adjust to consolidation of the underlying <br />materials, it is important that the foundation beneath the <br />channel pan be firm. Therefore, BRL shall commit to the <br />inspection and density testing of the prepared subgrade of the <br />grouted riprap pan. <br />