GENERAL32617

• Permit No: C1981020
• IBM Index Class Name: General Documents
• Doc Date: 9/7/1982
• Doc Name: PROPOSED DECISION AND FINDINGS OF COMPLIANCE
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

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XVI. Explosives - Rules 2.05.3(b) and 4.08
No explosives will be used or stored in conjunction with this operation. None
of the requirements of this section apply.
XVII. Backfi
sding - Rules 2.05.3(6)(b), 2.05.3(9), 2.05.4(2
4.13 and 4.14
Information regarding backfilling and grading of disturbed areas is presented
in Sections 2.2.2, 3.1 and 3.3 of Volume I and Appendix 0 of Volume V of the
application. L~tails of the waste disposal pile are presented in Sections 2.2.5
and 4.5.3.3.4 of Volume I and Appendix N of Volume V of the application. These
materials have been reviewed by the Division for compliance with the Rules and
Regulations.
The applicant proposes not to backfill the workings to achieve approximate
original contour. The application contains a description and cross-sections of
proposed backfilling and grading plans for the mine portal bench area and for
the haul road.
The upper haul road segment between the confluence of the Munger Creek Valley and
the unnarr~d tributary to the Munger Creek Valley (Sta. 67+00') to, and including,
the mine portal bench area, is characterized by steep slopes, commonly in excess
of 200. Under the regulations of the Rule 4.27, Operations on Steep Slopes,
the applicant is allowed variance from approximate original contour, if the
approximate original contour donfiguration will not achieve a static slope safety
factor of 1.3, as required by Rule 4.14. Ideally, the entire highwall shall be
backfilled to achieve a safety factor of 1.3. In situations in which a static
slope safety factor of I.3 cannot be achieved, the applicant proposes to backfill
to that configuration which will maximize the static slope safety factor of that
portion of the backfilled slope. Remaining portions of the exposed cut slopes
will be treated to achieve a surface which is as erosionally and as structurally
stable as is possible.
In response to Division com~mnt, the applicant developed typical backfilled
cross-sections, similar to the operational road cross-sections depicted in Figure
2.2-23. The applicant's detailed backfilling and grading proposals are supported
by thorough stability analyses of the proposed backfill and grading configurations
for the haul road and portal bench areas. The analysis demonstrated that the
redesigned reclaimed configurations' stabic slope safety factors exceed those
of the predisturbance natural slopes.
The applicant's original permit application contained several deficiencies with
regard to the underground development waste pile, which have been remedied in
supplemental submittals. In response to the Division's Preliminary Adequacy
Review, the applicant has prepared and submitted an acceptable geotechnical and
stability analysis of the proposed 25,000 cubic yard underground development
waste pile. This analysis determined that the pile will achieve a minimum static
slope safety factor of 1.684, based upon conservative assumptions of the waste
material's strength. The applicant is also committed to an inspection and
certification program which conforms with the requirements of Rule 4.09.1(11).
The applicant's plan for the disposal of underground development waste of the
Munger Canyon Mine is in compliance with the requirements of Rules 2.05.3(6)
and 4.09.