2010-06-02_REVISION - C1981019 - Laserfiche WebLink

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of Excess Spoil which begins on Page 20 (South Taylor/Lower Wilson-Rule 4, Page 20) in Volume 12. The chart below reflects the original permanent stockpile volumes approved with PR-02 and indicates the changes to the permanent stockpile volumes requested by TR-81. Permanent Fill Volumes PR-02 TR-81 West Taylor Fill 10, 000, 000 26, 045, 000 East Taylor Fill 50, 000, 000 18,141, 000 Total 60, 000, 000 44,186, 000 18. In the original permitting of South Taylor (PR-02) Colowyo proposed the East Taylor and West Taylor Fills as permanent fills. These two fills were based on a material swell factor of 20% and were to contain a total of approximately 60 million cubic yards of material (South Taylor/Lower Wilson-Rule 4, Page 20). According to the proposed revisions in TR- 81, the swell factor has been adjusted down to 15% (based on the decreased swell for the truck and shovel operation) and the total volume for the East Taylor and West Taylor Fills has been increased to approximately 70.3 million yards of material (an increase of approximately 10 million cubic yards). It would follow that if the material swell factor decreases the amount of excess spoil should necessarily decrease as well. Based on the decrease in swell from 20% to 15% the amount of excess spoil produced should decrease approximately 4.2% (in the case of the East Taylor and West Taylor Fills this would amount to a decrease in excess spoil of approximately 2.5 million yards). Further, based on the mine plan change for the South Taylor Pit approved with TR-69 (approved on 29 May 2008), Colowyo has changed the direction of mining to the West (as opposed to the original mine plan which mined to the East) into more shallow cover and better stripping ratios. This would suggest that the amount of spoil material from the box-cut would be further decreased. Please justify why the amount of excess spoil being placed in the East Taylor and West Taylor Fills is being increased rather than being decreased, as the aforementioned changes would suggest. Please justify and demonstrate why these changes are needed in the text under Rule 4.09 - Disposal of Excess Spoil, which begins on Page 20 (South Taylor/Lower Wilson-Rule 4, Page 20) in Volume 12. Response: Please refer Figure 1 and Map 198. The mine plan and the post-mining topography are being significantly revised with this TR-81 submittal. Due to the abandonment of mining plans extending through most of the NW14 of section 21 and the SE14 of Section 20 as shown on Figure 1, overall stripping volumes are being reduced. The South Taylor pit remains essentially a box cut that cannot be backfil/ed until the active mining is nearly complete. It still requires out-of-pit temporary spoil piles and the two permanent valley fills designated as East Taylor Fill and West Taylor Fill, as described originally in PR-02. This TR-81 seeks to move the toe locations of both of those fills to the north, approximately 900 and 600 feet respectively, and to use large temporary spoil piles resting over them. However, the increased permanent valley fill volume, plus the space provided for the overlying temporary spoil piles allows the new PMT in the pit area to closely approach pre-mining topography. This is discussed in more detail in the revised text