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relief slope and geologic structures. Conventional pit <br />development far a dragline operation would begin at a <br />IIGL~Dpl~r~e" (Ol1tCLbpplrXj) or shallow area and nrr Tiara tOWdLd • <br />deeper opal. 'Ihe advantage of this technique is lower <br />production costs in early years. However, the oust of <br />production beccm~es progressively higher as the pits advance. <br />At Seneca II, the geologic structure prevents this normal <br />progression and pits must be generally oriented perpendicular <br />to the cropline ar parallel to the dip of the seam. By <br />removing the overburden frarn recovery line to cropline in the <br />same pit, the oust of production is more constant over the <br />life of the mine. 'Ihe best techniques for orientation of pits <br />with respect to drainage patterns are to lay out a sequence of <br />pits where the natural drainage is away from or parallel to <br />the pits. Zhe techniques used at Seneca for dealing with the <br />relatively high relief, slopes, and geologic structure will be <br />discussed in the detailed mining prooediffe. A grourd control <br />plan for maxinnml stability of highwalls and spoil banks is <br />designed which takes into aooow~t angle of repose of the spoil <br />materials, blocky nature of the shot highwall, depth of the • <br />pit, water in the pit, etc. <br />A haulage road system is designed with roads of appropriate width <br />aryl grade to acc~mnodate the intended traffic. In marntainous <br />terrain, such as that found at Seneca, the wnstruction of <br />switchbacks is sometimes nece,sazy to maintain the flattest <br />possible grade and m;n;m;ye the area of disturbance. Safety berms <br />are utilized where required by steep side slopes. <br />Surface water control plans normally utilize ditches for overlord <br />diversion of surface water as well as pit sumps for collection and <br />pumping of surface and ground waters that enter the pit. Sediment <br />• <br />12-6 Revised 08/20/93 <br />