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2009-09-21_REVISION - C1981010
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2009-09-21_REVISION - C1981010
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Last modified
8/24/2016 3:55:41 PM
Creation date
9/22/2009 2:03:23 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981010
IBM Index Class Name
REVISION
Doc Date
9/21/2009
Doc Name
Proposed Decision and Findings
From
DRMS
To
Trapper Mining, Inc
Type & Sequence
PR6
Email Name
JDM
Media Type
D
Archive
No
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8. Appendix T of the permit application contains a slope stability analysis for the Horse <br />Gulch Fill utilizing a three-dimensional finite difference model. This analysis found <br />that horizontal lifts constructed by dumping material from a height of 400 feet will <br />result in a factor of safety for the Horse Gulch Fill of 1.45. The analysis also found <br />that contouring the dumped material to the final configuration of the design will <br />increase the long-term factor of safety to a value between 1.51 and 1.75. This <br />analysis demonstrates the Horse Gulch Fill is designed to attain the minimum long- <br />term factor of safety of 1.5 required for excess spoil fills (4.09.1(7)) and valley fills <br />(4.09.2(1)). <br />9. The Division finds the topography depicted in the final configuration of the K-Pit <br />Buttress Fill meets the definition of approximate original contour, per Statute 34-33- <br />103(3) and Regulation 1.04(13). The proposed topography closely resembles the <br />general surface configuration of the land prior to mining and complements the <br />drainage pattern of the surrounding terrain. Although there is a slight variation <br />between post-mining and pre-mining elevations, the variances of elevations are <br />consistent with Trapper Mine's previous and successful reclamation efforts. <br />VIII. Coal Mine Waste Banks <br />No specific approvals are granted to the applicant under this section. <br />IX. Coal Mine Waste <br />No specific approvals are granted to the applicant under this section. <br />X. Backfilling and Grading <br />Backfilling and grading is discussed under Section 3.5 of Vol. III of the permit <br />application. <br />1. The Division previously approved the applicant's request for additional time for <br />backfilling and grading following coal removal in a contour strip mine. A detailed <br />written analysis under 2.05.4(2)(c) has demonstrated that additional time is necessary. <br />The applicant is bonded for a maximum of four (4) spoil ridges at any time within <br />each pit area. Reclamation has historically been, and is proposed to be, completed at <br />approximately the same rate as the disturbance of new ground. (4.14. 1) <br />2. In the review of Trapper's application for a permit in 1981, the applicant indicated <br />that the post-mining topography cannot be absolutely predicted in advance. <br />Consequently, the Division (then the Colorado Mined Land Reclamation Division) <br />attached the following stipulation to the permit. <br />Stipulation No. 10: <br />THE DIVISION DIRECTS THE PERMITTEE TO MONITOR THE POST-MINING <br />TOPOGRAPHY OF THE BACKFILLED AND REGRADED SURFACES OF THE DISTURBED <br />Trapper Mine 32 September 21, 2009
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