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STATE OF COLORADO <br /> MINED LAND RECLAMATION DIVISION <br /> Department of Natural Resources C)T co 9 <br /> 1313 Sherman St., Room 215 <br /> Denver,CO 80203 { „ /* <br /> 303 866-3567 . �i. <br /> FAX: 303 832-81 06 '1876' <br /> Roy Romer, <br /> Governor <br /> Fred R.Banta, <br /> Division Director <br /> DATE: March 29, 1990 <br /> TO: Dan Mathews <br /> FROM: Jim Pendleton 'r <br /> RE: Review o raft Ad acy Comment Letter - King Coal #PR-02 <br /> In accordance with your request I have reviewed your draft adequacy letter for <br /> Permit Revision #PR-02 to the National King Coal underground coal mine. In my <br /> opinion you have correctly ascertained each of the apparent geotechnical <br /> adequacy concerns contained within the application for revision. <br /> Coal Mine Waste: <br /> They should discuss the projected waste volume to be produced, in order to <br /> ascertain whether it will be properly disposed. If they intend to backstow <br /> the waste, they must provide us with an MSHA approved backstowing plan. <br /> Otherwise they will need to prepare a proper coal mine waste disposal plan, as <br /> you referenced. <br /> Mine Subsidence: <br /> The permit is inconsistent, but does mention the development of subsidence <br /> cracks adjoining section 3rd East on page 21 . Obviously the development of <br /> such cracks could represent a significant hydrologic interruption to both the <br /> surface and ground water hydrology of the Pine Gulch drainage. The operator <br /> first needs to resolve the drainage's status as an Alluvial Valley Floor. <br /> Without a discussion of the probable hydrologic consequences, it is difficult <br /> to ascertain the probable effects. <br /> Further, the operator would have us believe that the subsidence cracking above <br /> 3rd East panel can be simply avoided by realigning the workings to obliquely <br /> intersect the cleat direction. This fact will have to be demonstrated <br /> somewhere outside areas which could potentially affect a drainage before they <br /> could be allowed to mine beneath the Pine Gulch drainage. Failing such a <br /> demonstration, extraction beneath areas which could materially damage the <br /> drainage must be restricted to development only, which normally recovers less <br /> than 35% of the in-place coal . <br /> cc: Jim Stevens <br />