2020-10-22_PERMIT FILE - C1981012A ‎(4)‎

• Permit No: C1981012A
• IBM Index Class Name: Permit File
• Doc Date: 10/22/2020
• Section_Exhibit Name: Section 2.05 Operation and Reclamation Plan
• Media Type: D
• Archive: Yes

111
Surface Mining near Underground Mining
No surface mining is currently taking place in the vicinity of the New Elk
Mine. To the Operator's knowledge, no surface mines are planned in the near
future which would conflict with the operation of the New Elk Mine.
Subsidence Survey. Monitoring and Control Plan
A subsidence control plan has been prepared for the New Elk Mine and is
included in Exhibit 24. All structures that exist in the permit and adjacent areas
are shown on Map 20- Sheets 1-3, Map 11 and Map 12. The structures are
listed in Exhibit 42 and Table 19.
The renewable resource lands existing in the form of the Purgatoire River and
associated alluvial valley floor are unlikely to be impacted by any anticipated
subsidence in the mining plan. The locations of these renewable resources are
shown on Map 20. The description of the renewable resource lands is in
Exhibit 8. The current mining plan under the Purgatoire River and
associated alluvial valley floor are development -only workings and do not
have any retreat panels. The extraction ratio is planned to be less than 50% for
these workings.
The stability of development -only workings, as well as retreat panel
workings was analyzed usingthe Analysis of Retreat Pillar
Mining Stability (ARMPS) computer code developed by NIOSH. The
program uses the modified Mark-Bieniawski pillar stability formula and
evaluates the stability within a zone comprising a number of pillars.
Development -only pillar dimensions were developed for areas such as
underneath the renewable resource lands mentioned above, and areas with
cover depth and mining height combinations that precluded the use of retreat
mining. Stable panel pillar dimensions were developed for various cover depth
and mining height combinations using ARMPS. The details of this analysis -
are included in Exhibit 24.
If subsidence has occurred in the permit area, caused by past mining, no
material damage to structures or renewable resource land has occurred. No
discernible effects can be attributed to subsidence induced by the old New Elk
Mine workings. This is supported by the stable condition of the Colorado
& Wyoming Railroad right-of-way and Colorado Highway 12. Any effect of
subsidence on the renewable resource lands located in the Purgatoire River
area is considered unlikely.
There are no structures that will be undermined using retreat methods and
subsided in this permit application. The details of structures 44, 45, 46, and
47 are shown in relation to the permit boundary and mine plan in Figure 19.
Mining detail, showing development -only mining areas and retreat (pillar
Section 2.05 RN -6 Repaginated 10/21/16