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Geotechnical Stability, by Merrick and Company) submitted in response to stipulation No. 14 of <br />the 1981 Orchard Valley Mine (Bowie No. 1 Mine) Permit, and which is included with the <br />Permit Application in Volume 6. The Division approved the alternative road specifications <br />based on this demonstration. <br />The reclamation plan approved in Technical Revision No. 28 allows for the retention of access <br />roads and the associated terraces. The presently permitted haul and access roads will be <br />narrowed to a 16 foot width within the 20 foot wide terrace corridor. The reclamation plan <br />requires that all other terraces be reclaimed. The operator had committed to removing the asphalt <br />between Steven's Gulch and the crushing and screening level and performing finish grading of <br />the road, which has been done. <br />In August 1986, the operator submitted a permit revision application to construct new portal <br />facilities, named the West Mine, in the East Roatcap Creek Valley. This application proposed <br />the construction of a new portal facility and haul road, because the existing portals at the Orchard <br />Valley Mine, now called the Bowie No. 1 Mine, had been rendered unusable by an underground <br />coal mine fire. The applicant proposed to upgrade an existing public access road to serve as a <br />coal haul road to the proposed portal bench. <br />The geotechnical specifications are found in Volume 6, prepared by Golder Associates, <br />consultant to the operator. This appendix presents the results of geotechnical investigations, <br />stability analyses and detailed engineering design for the portal bench cut and fill and the <br />accompanying haul road. The stability analyses are based upon projected cut slope <br />configurations and material mechanical properties obtained from material sampling and <br />laboratory analyses. <br />Stability analyses were completed for cross sections chosen at road stations believed to represent <br />potentially critical slope stability situations along the proposed upgraded haul road. As a result <br />of this slope stability analysis, the operator amended its original proposed road cut slope <br />configurations to use a Hilfiker wall, or equivalent, retention system. The retention system was <br />to be utilized as depicted on Sheet 7 of 10 of the Golder Associates report, entitled "Haul Road <br />(1)," to reduce the unretained cut slope heights to a maximum of 30 feet. The Hilfiker treatment <br />was applied between road design stations 29 +50' and 36 +50'. Unretained cut slopes will not <br />exceed a maximum slope gradient of 1.25h:1.Ov (horizontal to vertical) unless an appropriate <br />slope stability monitoring program has been approved by the Division. With an approved <br />monitoring program, cut slopes will be allowed to reach a maximum slope gradient of 1.0h:1.Ov <br />(horizontal to vertical). The stability analysis determined a minimum operational static slope <br />safety factor adjoining the upgraded haul road of 1.72. <br />As required in the approved reclamation plan, the operator removed and reclaimed that portion <br />of the haul road constructed to connect the existing public access road to the proposed portal <br />bench embankment across East Roatcap Creek (design plan road Station 32 +50' to 38 +50'). <br />The ford of an ephemeral stream with a watershed of at least one square mile was approved by <br />the Division since it would not seriously alter normal water flow, contribute to sediment load, or <br />cause adverse affects to fish or wildlife. The ford is located on East Roatcap Creek where the <br />BLM road, used to access the West Mine fan facilities, crosses this creek. <br />The R.O.M. stockpile haul road was constructed between May 10, 1976 and May 4, 1977. Minor <br />Revision No. 66 formally included this haul road into the permit application. The road had been <br />Page 19 of 42 <br />