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-38- J Pursuant to Rule 4.01.1(3)(c)(i), and in response to Division comment, 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 geotec.'xni.cal 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 t.'v:s analysis, the applicant made several design and reclaimed configuration amendments. in a1Z cases, the amended designs achieve final reclaimed configurations which achieve static slope safety factors in excess of the original undisturbed slopes. 3ecause of this imarovement 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 Eactor of the affected areas are below that normally desired Ear road cut slopes, the Division imposes the following stipulation upon pernit approval: Stipulation .`!o. 17 THE DIVISION DIP.ECTS SALT CREEK F17PIING CO.~IPAPJY TO I;75 Td LL SIGNS AT THE PER'97T BOUNDARY AND aT STATION 67+00~ ADJOINIJJG .THE .PAUL ROAD. THESE SICNS, LEGIBLE FROFf THE HAUL ROAD WHILE ..°RCCEEDINO TCWARD THE PORTAL BENC.Y SHALL .READ: "ROAD SLOPES SUBJECT TO ROGKFALL aND SLOPE FAILURE - PROCEED WITH CARE." Road Drainage Control Road drainage ditches are designed to convey surface runoff resulting from the 10-year, 24-hour storm event. AZ1 culverts conducting drainage beneath road surfaces will safely pass IO-year, 24-hour peak flows and will be appropriatelu installed. In some cases, discharges from the culverts nay be at velocities which are erosive. Care must be taken at all culvert d_'scharce points to dissipate energy due to t.Sese :xi.gh velocity discharges. Salt Creek ,Mining Company has installed protective de•rices at cul•~ert 3ischarce 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. T::e proposed road culvert installaticn scheme does not conform :~ia~ performance standards of Rule 4.03.i(4)(e)(vi)(Ai regarding culvert spacing. adherence to these spacing requirements ensures that drainage systems ::iii not be breached and excessive eresi on will not result. alternative speci fi ca dons are al'owed -nder the provisions of 4.03.1(J)(e)(•r') :~ the applicant can ,'e.monstrate that such speci_'_'cacons will not result in an increase in eroslon. .n .:va sarticular case, toe Ji vision would recommend the ias tai:a t. on of add`t_onai cvl vests, • particuiariu .n areas of stee^er road :^sd_'er.ts, vrer=ver a drai-ace crosses the road ias indi=aced bu ^entovr ~^es or. a .o pocra phis .nap).