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2.05.6(6) <br />(f)(iii)(A) <br />0101= I <br />The anticipated effects of planned subsidence are explained above and are <br />presented in detail in Volume IIIA, Exhibit 15, 17 and 21. <br />The measures to be taken in the mine to reduce the likelihood of subsidence <br />are explained above. The mine plan will leave support pillars under Pond P- <br />1, adjacent to Hubbard Creek, Terror Creek and near the outcrop. The long <br />term stability of the support pillars were evaluated in Volume IIIA Exhibit 15, <br />Section 1.9. A study performed by Hamid Maleki located in Volume IIIA, <br />Exhibit 16 shows the pillars in the main entries under Terror Creek have a <br />calculated factor of safety of 2.5 directly under the creek. To assure long <br />term stability, a pillar must have a factor of safety of 1.5 or greater. No <br />backstowing or backfilling of voids will be performed. The minimum pillar <br />factor of safety exceeds 1.4 near the rock storage area for the worst <br />assumed coal strength and load transfer conditions. Because this panel is <br />only needed for the short term, and will soon be backfilled to the top by <br />waste rock, subsidence is not expected for assumed continuous (nonfaulted; <br />Brinton 2009) strata conditions. <br />A limited extraction zone was established along the bleeder entries in the <br />vicinity of Freeman Gulch and the vent shaft in Freeman Gulch to assure <br />ancient land slides were not reactivated by subsidence. <br />Mining in low overburden areas adjacent to the possible fault trace is <br />explained in section (f)(ii)(B) above. <br />A limited extraction zone will not be established along Stevens Gulch per <br />Federal Coal lease #37210 stipulations in order to protect Steven's Gulch <br />Road from the impacts of subsidence since the overburden in this area is <br />approximately 1500 feet. <br />PR -14 2.05-163- 03/14 <br />