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2018-09-04_PERMIT FILE - C1981019A
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2018-09-04_PERMIT FILE - C1981019A
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Last modified
10/25/2018 7:08:41 AM
Creation date
10/5/2018 10:39:47 AM
Metadata
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Template:
DRMS Permit Index
Permit No
C1981019A
IBM Index Class Name
Permit File
Doc Date
9/4/2018
Doc Name
Volume 1 Rule 4
Section_Exhibit Name
4.01 Throuugh 4.30
Media Type
D
Archive
Yes
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RULE 4 PERFORMANCE STANDARDS <br />Topsoil will be removed prior to the mining disturbance according to the timetable established on <br />the Topsoil Handling — South Map (Map 28). As can be observed from this map, the initial topsoil <br />removed at the operation must be stockpiled; however, as the operation progresses, topsoil can be <br />immediately redistributed rather than stockpiled. <br />Revegetation will commence as soon as the topsoil has been redistributed and prepared for seeding <br />as described in Section 2.05.4. The area will be seeded with the seed mixture described in Section <br />2.05.4 as quickly as possible. <br />4.14 Backfilling and Grading <br />4.14.1 General Requirements <br />The mining operations of Colowyo will not employ the use of contour mining methods. <br />The following sample of calculations show that Colowyo does not have thin or thick overburden <br />as defined in Subsection 4.14.4 or Subsection 4.14.5. These calculations represent the approximate <br />conditions found in the field and show that there is always more than enough overburden to <br />reestablish the original elevation. As explained in the 1983 Annual Report, Colowyo currently <br />uses an average 20% swell factor for planning purposes. Dragline swell is estimated to be 23%, <br />and truck/shovel swell is estimated to be 17%. Approximately 45% of the overburden is removed <br />by dragline, and 55% by truck/shovel. Since all mining at Colowyo was conducted by truck/shovel <br />methods through 1979, the life -of -mine swell factor has continued to increase. <br />Example: 363 feet overburden, 47 feet coal, (these conditions are found along the western edge of <br />the pit in 1988), 20% swell factor <br />363 feet + 20% swell = final thickness = 1.06 <br />363 feet + 47 feet initial thickness <br />Example: 356 feet overburden, 49 feet coal (these conditions are found along the western edge of <br />the pit in (1988), 20% swell factor <br />356 feet + 20% swell = final thickness = 1.05 <br />363 feet + 49 feet initial thickness <br />The original permit application utilized at 17% swell factor to project the anticipated postmining <br />topography. <br />During the initial permit review process the anticipated swell factor was subsequently revised to <br />23% to ensure that the Streeter Fill volume was adequate to allow for sufficient pit development. <br />At that time, excess swell was anticipated to raise the elevation of the postmining topography by <br />about 5.3 feet, compared to the premining topography. As explained above, in 1984, as part of the <br />1983 Annual Report, Colowyo further refined its estimates based on measurements to date, and <br />currently uses an overall 20% swell factor for estimating purposes. As indicated in the Annual <br />Rule 4 Performance Standards 4-41 Revision Date: 5/25/18 <br />Revision No.: RN -07 <br />
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