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