GENERAL31616

• Permit No: C1981020
• IBM Index Class Name: General Documents
• Doc Date: 3/10/1993
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR RN2
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

3. The disposal area will be inspected on a regular basis by a
qualified professional specialist under the direction of the
professional engineer, experienced in construction of similar earth
and waste structures. Inspection by this person has been approved
by the Division as appropriate (4.10.2(1)).
4. An alternative subdrainage system for the coal mine waste area has
been proposed. The Division finds that such an alternative will
ensure the applicable static safety factor, stability of the fill,
and protection of the surface and ground water (4.10.3(5)>.
VIII. Backfillina and Grading - Rules 2.05.3(6) (b). 2.05.3(9). 2
Information regarding backfilling and grading of disturbed areas is
presented in Sections 2.2.2, 3.1 and 3.3 of Volume I, Appendix 0 of
Volume V and Sections 2.3 and 3.1 of Volume VI of the application.
Details of the underground development 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 permit contains a description and cross sections of proposed
backfilling and grading plans for the mine portal bench area, haul road
and central facilities area. The upper haul road segment between the
confluence of the Munger Creek Valley and the unnamed 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 Rule 4.27, Operations on Steep Slopes,
the applicant is allowed variance from approximate original contour, if
the approximate original contour configuration 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 1.3 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 comment, 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, portal bench and central facilities area. The analysis
demonstrated that the redesigned reclaimed configuration's static slope
safety factors exceed those of the predisturbance natural slopes.
As previously mentioned, Salt Creek Mining Company has proposed a
25,000-cubic-yard underground development waste disposal site to be
located adjacent to the Munger Canyon Mine. This waste rock pile will
cover 2.6 acres and will be 35 feet high (see Section 2.2.5 of Volume I
of the application). Roof fall rock from both the Munger Canyon and
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