2021-08-09_PERMIT FILE - C1981019A ‎(5)‎

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 8/9/2021
• Doc Name: Volume 1 Rule 4
• Section_Exhibit Name: 4.01 Through 4.30
• Media Type: D
• Archive: Yes

RULE 4 PERFORMANCE STANDARDS

Rule 4 Performance Standards 4-37 Revision Date: 7/20/21
Revision No.: MR-235
administration/shop/facilities area will be the last area to be reclaimed. A light duty road intended
for post mining use may be left as a postmining feature in this corridor with land owner consent.

In addition, Colowyo controls additional coal reserves west and south of Section 9 and 16, outside
of Permit C-81-019, that may be considered for future mine expansion. It is possible that the final
plans for Section 16 and Section 9 could change to provide for such expansion, with any plan
changes being addressed through an appropriate permit revision.

4.14.2 General Grading Requirements

The final graded slopes at the mining operation will not exceed the approximate original premining
slope grade as shown on the Postmining Topography Map (Map 19). Colowyo will retain all
overburden and spoil material on solid portions of existing or new benches. The final highwall at
the operation will be eliminated by backfilling overburden into the final pit area.

Small depressions of a holding capacity slightly greater than one cubic yard of water may be used
to create a moist micro climate to aid in shrub establishment. See Section 2.05.4, Planting and
Seedings Methods for further information regarding these small depressions. Also, several stock
watering ponds will be constructed to compliment the postmining land use. Providing a supply of
water is an integral part of the grazing postmining land use. Colowyo will not be mining on any
slopes above 20° as shown on the Premining Topography Map (Map 18).

Final grading before topsoil placement will be conducted in a manner that minimizes erosion and
provides a surface for the topsoil that minimizes slippage. Final grading will be accomplished so
that overall grades will not exceed lv:3h. The plan for backfilling and grading is shown graphically
on the Spoil Grading Map (Map 29).

4.14.3 Covering Coal and Acid and Toxic Forming Materials

Colowyo will not have any exposed coal seams remaining at the end of mining and reclamation.
Colowyo does not have any acid forming materials at the mine. For discussion on acid- and toxic-
forming materials, refer to Section 2.04.6. For disposal of noncoal wastes or materials
constituting a fire hazard, refer to Section 4.11.4.

4.14.4 Thin Overburden

Colowyo does not have a thin overburden situation as explained in Section 4.14.1.

4.14.5 Thick Overburden

Colowyo does not have a thick overburden situation as explained in Section 4.14.1.

4.14.6 Regrading or Stabilizing Rills and Gullies

The implementation of soil stabilizing practices outlined under Section 4.15.4 will lessen the
possibility that erosion can become a serious problem. Colowyo plans to continue using surface