GENERAL35863

• Permit No: C1980004
• IBM Index Class Name: General Documents
• Doc Date: 4/16/1985
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE FOR RN1
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

All portals and the sediment pond will be backfilled. The coal seam will
be completely covered with backfilled material. Drainage will be
restored to approximate pre-mining conditions.
Salt Creek Mining Company has proposed to partially backfill cut slopes
at the mine portal bench. Natural slopes in the vicinity are very steep
and complete backfilling of the existing cut slopes would be difficult.
At the time of the initial permit approval, the applicant had not
provided enough analysis to suggest that the slopes would be stable in a
partially backfilled situation. As a result, the Division attached a
stipulation (No. 14) to the initial permit which required the operator to
provide the Division with a specific proposal for the final configuration
of the portal bench cut. A response was received on June 13, 1983, and
the operator's submittal effectively resolved the Division's concerns
regarding the cut slope existing southwest of the office trailer at the
McClane Canyon mine portal bench. The operator demonstrated that the
proposed buttressing of that existing cut slope would improve the static
slope stability of the slope. In fact, a static slope safety factor of
1.311 was projected, as compared with the existing slope configuration's,
calculated at 1.234. The projected reclaimed configuration's static
slope safety factor therefore satisfied the requirements of Rule
4.14.2(1)(b).
The operator also stated in the response that "the outcrop highwall is it
fact a natural rock outcrop and was not a result of excavation." The
operator presented only a schematic cross-section on figure 3.1-1, which
indicated partial backfilling of the actual portal face up area.
However, the portal highwall has been extensively netted and rock
bolted. Therefore, the following stipulation to the permit is necessary:
11. WITHIN 60 DAYS OF PERMIT ISSUANCE, THE APPLICANT SHALL REVISE THE
PERMIT APPLICATION TO COMMIT TO BACKFILLING THE PORTAL FACE-UP AREA
TO THE ORIGINAL "STRAND LINE" OR CREST LINE OF THE ORIGINAL
UNDISTURBED SLOPE WHICH WAS EXCAVATED OUT DURING CONSTRUCTION OF
THE MINE BENCH AND PORTALS. THE SLOPE GRADIENT AND COMPACTION OF
THE BACKFILLED PORTAL FACE-UP AREA SHALL BE DESIGNED TO ACHIEVE A
MINIMUM STATIC SLOPE SAFETY FACTOR OF 1.3. COMMITMENT BY THE
APPLICANT TO THIS BACKFILLED CONFIGURATION SHALL NOT PRECLUDE THE
APPLICANT FROM SUBMITTING A FUTURE REQUEST TO THE DIVISION FOR
REVIEW AND APPROVAL OF AN ALTERNATIVE BACKFILLING SCHEME FOR THE
PORTAL FACE-UP AREA WHICH WILL MEET THE REQUIREMENTS OF RULE 4.14.2.
The initial plan for disposing of underground development waste generated
at the McClane Canyon Mine consisted of retaining all the material within
the mine workings. The approval of the first permanent regulatory
program permit did not allow for the placement of any such waste into a
waste pile at the McClane Canyon Mine. However, subsequent to the
~ initial permit approval, the operator requested and received approval
from the Division to temporarily store underground development waste on
the McClane Canyon Mine bench. The approval was based on review of an
analysis of the waste rock which indicated no problems associated with
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