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25. A bedrock buttress is depicted at the southeastern toe of Section D-D' in the October <br />2009 Shannon and Wilson Study and on Map 45. The mass was incorporated into the <br />stability analysis for this section, but no dimensions are presented on the height, slope, and <br />length of this structure. Please modify the October 2009 Shannon and Wilson Study to <br />include the design details, and modify the plan and D-D' cross-sectional views of <br />Map 45 to include the location and dimensions of the bedrock toe buttress. <br />Response: The toe hump visible near Station 23+00 on Section D-D' of Map 45 and on <br />Shannon and Wilson's Analysis Section D-D' is not a man-made buttress but is the existing <br />bedrock profile just before the northwest end of the pit. Because it is inclined upward it <br />does give the appearance of a shot rock buttress. Since it is the existing ground and not a <br />buttress, no change is proposed to the cross-section on Map 45 or to Shannon and <br />Wilson's Analysis Section D-D' which appeared as Fig. 2, Sheet 4 of 4 in their October 21, <br />2009 Addendum No. 3. That section D-D' re-appears now as Fig. 11, Sheet 4 of 4 in their <br />April 15, 2010 Revised Addendum No. 3. <br />Rule 4.14 - Backfilling and Grading <br />26. With the approval of Permit Revision 02, the Division approved a variance from AOC <br />for steep slope mining for the South Taylor Pit. This variance allowed a decrease in the <br />elevation of the backfilled areas as well as a decrease in the slopes of the associated <br />backfilled areas. The overall post-mining topography kept the pre-mining watershed <br />boundaries intact. With the submittal of TR-81, Colowyo has proposed to increase the <br />amount of permanent, out-of-pit spoil by approximately 10 million cubic yards AND <br />decrease the swell factor. This will lead to a further overall decrease in the post-mining <br />topography of the South Taylor Pit by more than six feet, on average, over the entire pit <br />area of approximately 960 acres. Rule 4.14.2(d) states that "(b)ox cut spoil or initial cut <br />spoil may not be permanently disposed of outside of the mined area unless the applicant <br />demonstrates that such material is not required to achieve approximate original contour of <br />the area in accordance with Rule 4.09.1" (emphasis added). While the Division did <br />approve the currently approved permanent, out-of-pit spoil piles in PR-02, with TR-81 <br />Colowyo is requesting the Division to approve a further variance (decrease) in AOC, <br />although such a variance is not specifically requested in the revision. Based on the <br />Division's review of the currently approved Map 19B - Post-Mining Topography-South <br />Taylor Area and the proposed Map 19B, there do not appear to be any changes to the <br />post-mining topography in the South Taylor Pit. The only changes noted on the proposed <br />Map 19B are to the East and West Taylor Fills. Pursuant to Rule 4.09.2(d), please <br />provide the Division with documentation and justification why the additional 10 <br />million cubic yards of material proposed for the South Taylor Fills will not be needed <br />to meet AOC. The Division cannot make a finding to approve further decreasing the <br />final topography of the South Taylor Pit by an average of five feet (up to 17 feet with <br />the change in swell), over the entire pit area while approving an increase in the <br />volumes of the East and West Taylor permanent fills. <br />Response: As stated in the response to Item 18, this submittal seeks to significantly <br />revise the PR-02 approved post-mining topography and all volumes have been <br />recalculated.