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lo] <br />-TAl\7'OP YI~17:0 <br />5ountaintop mining is that type of steep slope operation Rhich re• <br />mote; the enure upper strata of the mountain on Rhich the operation <br />is lxing conducted. This type of mining approach has been increasing <br />in popularity oi•er the past several years as the economics of mining <br />have changed allon•ing greater or larger stripping ratios (Fig. 5). <br />5loimtainu mining also produces a massive amount of spoil to be <br />handled and stabilized in a very difficult environment of steep slopes <br />and higgh rainfall. Some approuhes have been developed which kap <br />virtually all of the spoil on the mountaintop and most recently have <br />beers described in the December 1978, issue of Coal dge. Retention of <br />spoil on the mountaintop bench has advantages over placement of <br />such spoil in calleys and hollows Hoivel•er, such placement off the <br />mountaintop does oRer the possibility of improved land uses through <br />the creaUOn of significantly expanded areas of flat ]and. Ii.R. 2 pro- <br />rides some specific standards with trspect to the disposal of surplus <br />spoil off the mine bench (sea 515(b)(11)). Surplus spoil disposal <br />areas must be carefully engineered to avoid instability drainage con- <br />trol problems, and erosion. Recent field studies for the ~nl-ironmental <br />Protection Agency have identified prob]erlu Kith some approaches <br />to the disposal of spoil in mountain valleys or hollows. The consult <br />ants to EPA. concluded that the ultimate stability of spoil disposal <br />technologies being used in the calleys and ho]]ofvs of several Ap• <br />pa)achiea States are urilmoRn.• Given the size and the complenty <br />of the engineeri»g involved for the disposal areas, specific standards <br />such as the foltoeing should be considered <br />Carefully place durable rock darns through the complete <br />leri,.~t.h of t}ie proposed fill area. Shales should be avoide$ in the <br />rnnslrudion of such drains because of the danger of Reathering <br />•of the shales leadingto blockage of the drain. <br />Drnins must be placed running from all seeps or springs in the <br />fill area to the toe of the fill. <br />Sediment ponds should be placed below the toe of each fill to <br />catch all drainage. <br />Excess spoil materiel should be placed and eompadzd in lifts <br />or stair step-like benches insuring that particle alinement will lead <br />to be. perpendicular to the typical failure plane. End or side dump <br />11ig off the upper benches should not be used either t0 cr'eatt the <br />beach drain or to handle excess spoil after the drain is oon• <br />atrvded. <br />Lifts ahov)d be contoured so that all drainage flows oft the fill to <br />rip-rapped drainagge Rays constrvded in undisturbed material on <br />either side of the fill. <br />Rock corns from the drainage svsterri should not. protrvde above <br />the. fill mass because they mac contribute to erosion of the fill face <br />it the aurlace of the core~mes silted at the bench-colt interface. <br />This melfundion of the Rater diversion system could cause Rater <br />to pond on the bench, then ffoR doRn the fill face. <br />Woody vegetation removed from the mine or ho]]oR fill area <br />should not be placed in the fill mass because it Rould endanger the <br />stability of the fill. <br />•s~d.e..e~f.r a~.s...e.e y a.qa 1/Mr.y Ysaa•: S.ns.y-siA,e )+n a~1 r•s.• <br />f•Aly a•.ewl, Interim t•a•n- 67•nr •a0 l.ea, a+nratsuh 16e.froemeeul Pt•1•eUem <br />•a•nq. Qstlnfutl. 0114 Y•rU lffT. trait repeR <br />~_ <br /> <br />