2008-03-04_GENERAL DOCUMENTS - C2006085

• Permit No: C2006085
• IBM Index Class Name: General Documents
• Doc Date: 3/4/2008
• Doc Name: Proposed Decision and Findings of Compliance
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

monitoring and/or control plan for each structure.
Subsidence monuments will be established in a grid over panels in two
locations, one over one of the early panels to be retreat mined and another
in a separate location where overburden thickness is different. Survey data
from these subsidence grids will be used to verify subsidence predictions
and to verify predictions including angle-of-draw. Survey monuments are
also proposed at various structures including structures, 3A, 2B, 3B, 4B,
5B, 6B, and 7B. These monuments will detect the onset of subsidence or
the lack of subsidence depending on the location of the monument. Pre-
subsidence inspection will be conducted at all structures and the
subsequent reports will be included in the permit application after
completion. The results of the monitoring program will be submitted to the
Division semi-annually. The monitoring program is designed to extend for
a time, beyond cessation of mining in any area, consistent with the need for
verification of the subsidence prediction.
Natural sandstone cliff faces outcrop in the NW1/4 NW1/4 of Section 24
T19S R70W over Panels 21, 22, and 23 shown on Map 7. Subsidence
cracking at the surface due to tension and compression of more brittle rock
units has been known to cause and/or exacerbate rockfall along cliff faces.
In some cases, rocks have moved considerable distances downslope and
can be a danger to structures below. The Division believes it is necessary
to determine the level of hazard below these cliff faces and determine
whether mitigation or modification of the mine plan is necessary to
minimize the risk of subsidence-induced rockfall. Mining is not planned for
these panels until years 11-15 of the proposed mine plan. Therefore, the
following stipulation is necessary;
Stipulation No. 3
RETREAT MINING IS PROHIBITED IN PANELS 21, 22, AND 23 UNTIL
SUCH TIME THAT A HAZARD ANALYSIS IS COMPLETED ALONG THE
CLIFFS AND SLOPES ABOVE THESE PANELS AND APPROPRIATE
MITIGATION AND/OR SUBSIDENCE CONTROL MEASURES ARE
REVIEWED AND APPROVED BY THE DIVISION.
XVI. Concurrent Surface and Underground Mining
No specific approvals granted.
XVII. Operations on Alluvial Valley Floors
A. The Division has determined that an alluvial valley floor exists within the
adjacent area. Therefore, the following findings are in order for the alluvial
valley floor known as the Arkansas River AVF located 2 miles northeast of
24