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Mr. Roy Kazo Seneca Coal Company 7/14/2004 Page 4 Comment 2. Response accepted. Comment 3. Tab 20 has been updated as requested. The Division has noted some discrepancies between the approved Post-Mining Topography Map and the proposed Post-Mining Topography Map (Exhibit 20-2). For instance at a location to the northeast of I-I' in the North Valora Pit, the slope on the approved Exhibit 20-2 is 4h: lv, whereas on the proposed revised Exhibit 20-2 the slope has increased to 3h: lv in the same location. This location has been final graded, topsoiled, and seeded as part of the 2001-2002 polygon area associated with CO- 2003-012. The Division is concerned that there may be other locations where the approved post mine topography differs from what is actually on the ground. What aze the quality control procedures utilized by SCC to ensure that the final grade is consistent with the approved post mining topography? Other changes were noted on the revised Post-Mining Topography Map (Exhibit 20-2). In the same location noted above, post-mining cross-section I-I' has changed in location and length. Likewise cross-section G-G' has also changed from the approved Exhibit 20-2. Please update these changes on Exhibit 20-2A Pre Mining & Post Mining Cross- Sections Map. As indicated in the attached memo from Byron Walker, slopes of over 3 horizontal to 1 vertical appeaz to be subject to a high probability of failure. This is evident in two locations at the Yoast Mine. One location is the 2003 variance azea where the slope was measured to be 1 vertical to 1.7 horizontal in the vicinity of a developing crack. Another location is the slide above Pond 012. A slope of 1 vertical to 2.8 horizontal was measured in a small portion of the slide. To ensure compliance with permit conditions and to ensure stability of the final graded slopes, please place spoil material no steeper than 3 horizontal to 1 vertical at the above-referenced locations. This includes the slide area above and to the east of Pond 012 and the 2003 variance azea encompassing the location of the proposed haul road. Upon careful review of the proposed Post-Mining Topography Map and Backfilling and Grading Plan (Exhibits 20-2 and 19-1A), it appeazs that the proposed slope above and to the east of Pond 012 ranges from 2.3h:1v to 3.2h:1 v and in the 2003 vaziance area in the location of the haul road the slope is proposed at 2.8h:1 v. Based on the above findings, the Division is requesting that SCC revise all appropriate maps and exhibits to reflect slopes no steeper than 3 horizontal to 1 vertical in the areas above and east of Pond 012 and in the location of the proposed haul road at the 2003 variance area.