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-38- Pursuant to Rule 4.03.I(3)(c)(i), and in response to Division cormnent, the applicant completed a mathematical stability analysis, based upon appropriate material strength data, to determine the static slope safety factor of the designed cuts. The analysis considered worst-case situations characteristic of the materials and cut slope configurations proposed within the plan. Alternatively, the applicant chose to demonstrate, through appropriate geotechnical analysis, that a safety factor of Zess than 1.5 would not result in significant environmental harm or harm to the public health and safety. The supplemental stability analysis of the haul road cut slopes considered the relative stability of the various cut slopes prior to disturbance, in their present pioneer road configuration, as reconstructed, and as reclaimed. In response to preliminary results of this analysis, the applicant made several design and reclaimed configuration amendments. In aZZ cases, the amended designs achieve final reclaimed configurations which achieve static slope safety factors in excess of the original undisturbed slopes. Because of this improvement in slope stability for the affected areas, the Division finds that the proposed construction of the improved haul road will not result in significant environ- mental harm or harm to the public health and safety. However, because the static slope safety factor of the affected areas are below that normally desired for road cut slopes, the Division imposes the following stipulation upon permit approval: Stipulation No. 17 THE DIVISION DIRECTS SALT CREEK MINING COMPANY TO INSTALL SIGNS AT THE PERMIT BOUNDARY AND AT STATION 67+00' ADJOINING THE HAUL ROAD. THESE SIGNS, LEGIBLE FROM THE HAUL ROAD WHILE PROCEEDING TOWARD THE PORTAL BENCH SHALL READ: "ROAD SLOPES SUBJECT TO ROCKFALL AND SLOPE FAILURE - PROCEED WITH CARE." Road Drainage Control Road drainage ditches are designed to convey surface runoff resulting from the IO-year, 24-hour storm event. All culverts conducting drainage beneath road surfaces will safely pass 10-year, 24-hour peak flows and will be appropriately installed. In some cases, discharges from the culverts may be at velocities which are erosive. Care must be taken at all culvert discharge points to dissipate energy due to these high velocity discharges. Salt Creek Mining Company has installed protective devices at culvert discharge points at existing operations which demonstrate little to no erosion. if the applicant continues to use these measures during the proposed operation, there should be little problem with erosion at discharge points. The proposed road culvert installation scheme does not conform with performance standards of Rule 4.03.1(4)(e)(vi)(A) regarding culvert spacing. Adherence to these spacing requirements ensures that drainage systems will not be breached and excessive erosion will not result. Alternative specifications are allowed under the provisions of 4.03.1(4)(e)(vi) if the applicant can demonstrate that such specifications will not result in an increase in erosion. In this particular case, the Division would recommend the installation of additional culverts, particularly in areas of steeper road gradients, wherever a drainage crosses the road (as indicated by contour lines on a topographic map).