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iiiiiiiiuiiiiiiiii <br />999 <br />STATE OF COLOlZADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Deparimem of Natural Resources <br />I J 13 Sherman SL. Room 215 <br />Denver. Colorado BU?03 <br />Phone: 130JI 866-156% <br />FAS IJUL 8J2~S10h <br />DATE: January 7, 1999 <br />TO: Joe Dudish <br />FROM: Jim Pendleton <br />RE: Bowie N Niir <br />mini <br />a <br />DEPARTMENT OF " <br />NATURAI . <br />RESOURCE. <br />Rny Ruiner <br />Governor <br />lames 5 Lochhead <br />E•ecuuve D~reclor <br />7 Michael 0. Long <br />i .~G Orrs~un Dueaur <br />~R'07 - Geotechnical Adequacy <br />C-96-083) <br />I have reviewed the technical revision application TR-07, which you forwarded to my attention. <br />With the recent delay of the BLM's proposed federal lease decision, Bowie Resources, Limited <br />(BRL) has amended its intended technical revision, restricting it to the previously permitted area. <br />BRL now proposes to conveR from conventional to longwall mining within the current permit <br />area. BRL projects that this will provide two years of reserves. BRL anticipates a one year delay <br />in the federal lease decision. <br />The conversion from conventional room & pillar mining to longwall extraction has minimal <br />con<equence in itself. The chazacter of the subsidence profiles may change slightly because of <br />more complete coal recovery within panels. However, the rnaximum expected subsidence <br />magnitudes should still fall within the conservative projections included within Exhibit l5 to the <br />permit. <br />My only adequacy recommendations regard a few minor modifications to the Subsidence <br />Handbook statements within Exhibit 15. The subsidence handbook summarizes the control plan <br />methodology regarding vazious structures, springs, etc <br />(a) In addressing "Ponds",BRL proposes to report monitoring in the "Annual Subsidence <br />and Hydrology Report". In the interest of timeliness, L recommend [hat we require BRL <br />to notify the Division within ten (l0) days if any subsidence-related pond damage is <br />discovered. <br />(b) Similarly, in addressing "Colluvial Deposits -Springs",BRL proposes to report <br />monitoring in the "Annual Subsidence and Hydrology Report". In the interest of <br />timeliness, 1 recommend that we require BRL to notify the Division within ten (10) days <br />if any subsidence-related spring damage is discovered. <br />