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c. While Colowyo is proposing to regrade the majority of the South Taylor area to <br />approximate original contour, there is still a large area on the east side of the pit that will <br />remain below AOC. Based on a review of cross-section ST-C-ST-C', from approximately <br />station 38+00 to approximately station 70+00, this area will be up to 100 feet lower than <br />the pre-mining topography. Please explain why Colowyo is proposing to lower the post- <br />mining topography in the east portion of the South Taylor Pit by up to 100 feet. <br />Response: This area presently has mine facilities and is outside the South Taylor mining limit. <br />These facilitie would delay any filling in the immediate area. By filling in the Section <br />16 slot and haul road, the highest point in the area has shifted northward on the <br />proposed postmining surface. <br />d. On cross-section ST-A-ST-A', from approximately station 0+00 to approximately <br />station 10+00 there is a small "bump" of backfill shown that is approximately 20 feet high. <br />There is no disturbance shown on this area on Map 19B that would account for this <br />"bump". Please review cross-section ST-A-ST-A', from approximately station 0+00 to <br />approximately station 10+00 on Map 20B. If this "bump" is, in fact, a true feature, please <br />add it to Map 19B and explain what it is. If this "bump" is a remnant from previous <br />versions of the post-mining topography please revise as necessary. <br />Response: This 20 ft high bump is a CAD error based on the method of developing the profile <br />line. The error has been eliminated and the "bump" no longer exits. The premine <br />topo now matches the PMT topography at stations 0+00 to 10+00. <br />44. With the submittal of the responses for Technical Revision 81, Colowyo has provided <br />updated pages South Taylor/Lower Wilson - Rule 4, Pages 30-32. These pages <br />encompass discussions on Rule 4.27, operations on steep slopes. Based on discussions <br />with the operator and based on the proposed post-mining topography maps, cross-sections <br />and mine plan map (Maps 19, 19A, 20, 20A, 20B and 23A) provided with the responses, it <br />does not appear as though Colowyo will be operating on steep slopes. The steep slope <br />mining was the area in the east of the currently approved South Taylor Pit, which is now <br />proposed for elimination with this revision. A review of Map 19A - Post-Mining <br />Topography-South Taylor Area and the associated cross-sections, it appears as though <br />Colowyo is returning the pit to approximate original contour and no longer requires a <br />variance from AOC for steep slope mining. Based on a review of the enclosed materials <br />and revised pages South Taylor/Lower Wilson - Rule 4, Page 30-32, the Division has the <br />following questions. <br />a. On revised page South Taylor/Lower Wilson - Rule 4, Page 30 (beginning at Rule <br />4.27) there is a discussion of the steep slope mining conditions in the South Taylor Pit. <br />Since Colowyo has proposed to eliminate the steep slope areas from the South Taylor <br />Pit, this discussion is no longer valid. The Division recommends leaving this information <br />in the permit text for historical purposes but all of the language needs to be changed to <br />discuss what was originally permitted and what Colowyo currently has permitted (is <br />proposing to permit). Please update the text on page South Taylor/Lower Wilson - Rule <br />4, Page 30 to reflect the historic nature of the original steep slope mining conditions in the <br />South Taylor Pit. Please include a discussion of the changes made to the mine plan, <br />post-mining topography, permanent fills and the elimination of the steep slope areas in <br />this section.