2015-08-14_REVISION - C1982056

• Permit No: C1982056
• IBM Index Class Name: Revision
• Doc Date: 8/14/2015
• Doc Name: Adequacy Response 3
• From: Twentytmile Coal, LLC
• To: DRMS
• Type & Sequence: PR10
• Email Name: JLE
• Media Type: D
• Archive: No

26b) On revised page 2.05-191.8, the applicant indicates subsidence monitoring of RCR 33 and 27 will be
conducted quarterly while active longwall mining is occurring. Please clam; does TC intend to monitor
both these roads the entire time active longwall mining is occurring in the WCR? Or, will monitoring be
initiated when the longwall operation is within a specific distance to these structures? If so, please
indicate this distance.
This issue is considered resolved. However, revised page 2.05-191.8 cuts the end off the last bulleted
paragraph on this page. The bulleted item in question begins with "Permittee shall, at its expense,
fund... ". The last sentence and a portion of the second to last sentence is cut off. Please revise this page to
include the missing text.
Response: Due to page revisions, the referenced text shifted to the top of the next page (2.05-191.9) —
Please see attached pages for reference, no revision necessary.
27b) On revised page 2.05-191.9, the applicant indicates subsidence monitoring will be conducted at the
railroad. A trigger has been specified when monitoring will be initiated for this structure, but a frequency
of monitoring (daily, weekly, monthly... etc) is not specified. Please revise this section to indicate the
frequency the railroad will be monitored. A new revised page 2.05-191.9 was not included in either copy
of the technical adequacy review response. Please submit an updated page.
Response: Generally, monitoring will be on a weekly basis (quarterly for the County Road) during active
mining, and limited to the area(s) of active undermining. If monitoring indicates a significant variance in
subsidence from that predicted by the subsidence evaluation, or other concerns, monitoring frequency
may be modified, as appropriate. Pages 2.05-191.8 and 191.9 have been revised to reflect this
consideration, and copies of the revised pages accompany these responses for replacement in the PAP.
30b) The Division agrees that placing signs at the entrance of County Road 33 into the subsidence area would
be a good practice. Also, the Division requests that visual monitoring of the area in question be conducted
during the time periods TC will be monitoring County Road 33 for subsidence. A map is enclosed that
outlines the area of concern. Please revise the subsidence monitoring plan submitted for County Road 33
to include conducting visual monitoring of this area and a discussion of what actions will be taken should
unstable conditions and rockfall be observed.
Also; Map WC 23 Wolf Creek PR 14-10 Mine Plan Modification, depicts the subsidence monitoring area
for County Road 33. It appears the monitoring area for County Road 33 does not cover the entire length of
the road within the projected subsidence effects boundary as depicted on the map. Please revise this map
to extend the subsidence monitoring boundary the entire length of the road projected to be within the
subsidence effects boundarv.
Response: TC will commit to visual monitoring of the rock outcrop area in conjunction with the County
Road surveys during active undermining. If rockfall is observed which could reasonably pose a safety
hazard to motorists on this road segment, TC will coordinate with the County to place Jersey barriers or
similar protection along the edge of the road to catch any rockfall. Map WC23 has been revised to extend
the designated road subsidence monitoring zone and copies of both the revised map and text accompany
these responses for replacement in the PAP.
Remaining Outstanding Items From Technical Adequacy Review 2
6b) A new revised page 2.05-191.9 was not included in either copy of the technical adequacy review response.
Please submit an updated page.
Response: Page 2.05-191.9 has been revised under the two preceding responses and copies are provided.