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<br />_ ' ~~ • •~w.,DRAFT GE07ECHNICAL FINDINGS s• .a•-;='
<br />"~~ `~ 'MT. Gl3NNiSON N0. 7 UNDERGROUND. COAL MINE
<br />PfRl4IT REVI$YON APPLS~CkTION - UPPER :WASTE ROCK PILE
<br />_ Coal Processin~a Waste and ,Non-Coa1~=W~rre~ 5'nq~Was~e •
<br />West Elk Coal Co~pny applied for a; permit revision to~allow the construction
<br />of an upper waste-rock pal"e'>in October.-af 1984.. 'Ihe opera-to?~„had:,n_atetl ,irs.:
<br />intention to construct an-upper waste pile in•the original permit
<br />application. The permit"trevision application represented the submission of a
<br />detailed engiNeei•ing plan for that .structure, for which a general plan had
<br />earlier beefif~~ubmiti¢ed' ' . ~ • • .
<br />West Elk Coal=~prdpasea..within~thetamended permit Yeviston application, to
<br />construct a five, nill~or~rton eoal•.:pitocessing waste,,pil,e. The refusq will
<br />consist of ccs~rrse°coa? re~e'ct ahd deveiopmenR wrastg„rock.:- ,The mine projects
<br />waste product"iort'at a ~rat'e~tii"~150~D0 tons ~ft~r the~;::frst.,Xeec and lOb,000 tons.
<br />per year the'reaf2er~ il"pteccompieteti waste pile structure will cover
<br />approximately .4U acre5,,,aa~;ati=ej~n a maximum thickness..of 160 .feet.
<br />The waste pile will.have-2;5'H:1V,(fiorizontal tQ_vertieal) facial, slopes with
<br />30 foot wide benches at SO:foot:vertical intervals. The.ovecall~final facial
<br />slope will be ,approxi.mately;3 H:1V (horizontal to,.vertical slope ;of
<br />approximately 18.,2.degrees);in order-to fa.~ilitate..reclamation. Samples o€..-~:`
<br />currently produced waste;.were co}.lected antl-tested, in order to provide
<br />material properties-•for•a-mathematie'a1 stability analysis. Samples were also ,
<br />collected and-tested of-subgrade cpl1avium and bedrock for the same purpose.
<br />The stability _analysis,projectep-a:m-inimum static slope safety factor of x.64
<br />for an overall f.aci:al.a~t•ope;of=2,S~H.1V, ste$per then the requested
<br />configuration.
<br />At the reque,xt,,of~r<F~e,Di.vison;,West.E;9k,Coa1 Company. also completed an
<br />analysis of the~potent~al;stability,effe~ts upon"the F-Sewn., from the
<br />placement of :a five;Million-t.On surchercp.load upon the existing: workings
<br />within the mi,ae. The;,plaFl_Galls for•~apProximately the eastern half of the
<br />waste pile Go;;be,undermi~ed. In completing,this analysis, the operator
<br />assumed:
<br />1. An.gatim~te~canfiguration a~•the.waste pile reaching elevation
<br />' ii,$80 f_.eet.akgye,:sea,levei`...
<br />2. No~segondary exi:ractop beneath. the. pile.
<br />3. No~~arrier~pillars,-.eve~,ahou~`b~one..is:plagn~d..
<br />4: A,Centangor~s-ccaFkg~ciSt;i.ng_from-t#e:.e]evatiion of tfie F-Seam's
<br />flger;to-the,g~ound sus#,age~atthetop,of ttre,pile.."~
<br />`~ ,
<br />Two separate c4asezget~ve,strengt~s,,weFe~assumed for the floor clay beneath
<br />the f-Seam (an~3e!~f ~;~'~~]~£~,~,~t?~a-°t9°,~~AheS~~OO ;,a„350 lbs, mr squire .~ ,
<br />foot,: angle of int~~a1 #tacr~~r~,=:~ .,.F.ph"~s~pn ~~4,~,2DLL~~b$ ~ieR ~~a~ ~`~
<br />foot), resLiting in safexyyfarto~rs_;gl~ea~-ert an t:~f2'.'
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