GENERAL43391

• Permit No: C1981038
• IBM Index Class Name: General Documents
• Doc Date: 4/9/2004
• Doc Name: Amended Proposed Decision & Findings of Compliance For RN4
• Permit Index Doc Type: Findings
• Media Type: D
• Archive: No

existing road embankments have a minimum safety factor of 1.25, and that the road cuts have a
minimum safety factor of 1.5 or that a lesser safety factor will not result in significant
environmental harm or harm to the public health or safety (4.03.1(3)(c)(i) and (3)(d)(ix), and
4.03.2(3)(C)(i) and (3)(d)(ix)).
The operator has demonstrated that the haul road and access roads are stable and will continue to
meet the performance standard. The demonstration was supplied in a report (Phase I[ -
Geotechnical Stability, by Merrick and Company) submitted in response to stipulation No. 14 of
the 1981 Orchard Valley Mine (Bowie No. 1 Mine) Permit, and which is included with the Permit
Application in Volume 6. The Division has approved the alternative road specifications based on
this demonstration.
The reclamation plan approved in Technical Revision No. 28 allows for the retention of access
roads and the associated terraces. The presently permitted haul and access roads will be
narrowed to a 16 foot width within the 20 foot wide terrace corridor. The reclamation plan
requires that all other terraces be reclaimed. The operator has committed to removing the asphalt
between Steven's Gulch and the crushing and screening level and performing finish grading of
the road.
In August 1986, the operator submitted a permit revision application to construct new portal
facilities, named the West Mine, in the East Roatcap Creek Valley. This application proposed
the construction of a new portal facility and haul road, because the existing portals at the Orchard
Valley Mine, now called the Bowie No. I Mine, had been rendered unuseable by the
underground coal mine fire. The applicant proposed to upgrade an existing public access road to
serve as a coal haul road to the proposed portal bench.
The geotechnical specifications are found in Volume 6, prepared by Golder Associates,
consultant to the operator. This appendix presents the results of geotechnical investigations,
stability analyses and detailed engineering design for the portal bench cut and fill and the
accompanying haul road. The stability analyses are based upon projected cut slope
configurations and material mechanical properties obtained from material sampling and
laboratory analyses.
Stability analyses were completed for cross sections chosen at road stations believed to represent
potentially critical slope stability situations along the proposed upgraded haul road. As a result of
this slope stability analysis, the operator amended its original proposed road cut slope
configurations to use a Hilfiker wall, or equivalent, retention system. The retention system will
be utilized as depicted on Sheet 7 of 10 of the Golder Associates report, entitled "Haul Road (1),"
to reduce the unretained cut slope heights to a maximum of 30 feet. The Hilfiker treatment will
be applied between road design stations 29+50' and 36+50'. Unretained cut slopes will not
exceed a maximum slope gradient of L25ha.Ov (horizontal to vertical) unless an appropriate
slope stability monitoring program has been approved by the Division. With an approved
monitoring program, cut slopes will be allowed to reach a maximum slope gradient of l.Oh:1.Ov
(horizontal to vertical). The stability analysis determined a minimum operational static slope
safety factor adjoining the upgraded haul road of 1.72.
As required in the approved reclamation plan, the operator removed and reclaimed that portion of
the haul road constructed to connect the existing public access road to the proposed portal bench
embankment across East Roatcap Creek (design plan road Station 32+50' to 38+50'). In addition,
the operator will partially backfill the road cut slopes during reclamation in order to narrow the
road from an operational width of 26 feet to a width of approximately 15 feet, similar to that of
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