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-=~_..~ However, in some lnstantes where suitable quality coal is near the surface, the <br />overburden may be removed with a canhination of dozers and scrap@rs. The over- <br />burdFn would then be harp ed ca a stockpile oc placed qn mined-out areas far even- <br />tual regrading and retopsoiling. <br />Tht prin::iple mining method used at Trapper is dip-li_ne mining, i.e „ rsining in <br />strips para1.1e1 to the flotm hill dip of the coal Seams, Each pie is adjacent and <br />pat allel Co the peevioun oRe. Pit widths vary aecocdLng to the specific site. <br />Typically, lath cut is initiated near the coal outcrop and workefl down the hill <br />until the dipping coal becomes Coo deep to recover economically. On occasion, <br />the out may be worked up Che hill. when more than one seam is recovered, the <br />patting is removed in one a£ several methods, Thin partings up to ten feet thick <br />are removed with a dozer, backhoe or similar equipmenC. Thicker partin~+s are <br />removed with a drag line, parCing may be stripped up-dip or down-dip depending on <br />the particular situation. SCrike-line mining may be performed instead of the <br />present dip-line mining method iE geologic conditions allow. <br />The top of the uncovered coal is cleaned with zquipment such as a front-end <br />loader, motor grader, of rubber tired dozer. The coal is then either ripped with <br />a dozer or dri:Lled with a twin-mastHd coal drill and Chen blasted. Hole spacings <br />vaey depending on coal thickness, <br />The hales are loatled with AN-PO or other blasting agents and stemmed with drill <br />cuttings, The blast circuit is then completed and the blast is initiated (refer <br />to Section 3.4). <br />Large baCkhues or front end loaders are used to load the c4 al into haul trucks. <br />Thu coal haulers Cransport the coal from the pit to the power plant's grizzly or <br />a coal. stockpile. The coal haulers exit the pit via an inclihed ramp and enter <br />onto the haul road system ChaC connects each pit Co [he power plant's grizzly and <br />the coal stockpiles. At a lacer date, a conveyor system may replace part of this <br />truck haul. <br />3-14 <br />REVISED FEB 13 `87 <br />