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<br />The Effect and source of Water <br />Inflow to the Eagle No. 5 Mine, 2 67est Mains <br />- A Geologic Assessment - <br />Introduction <br />u4t Jul,~..,,~r,. 19$1, mining. op~xations withiq the Eagles <br />~~'hE=`7 't+~'est Mains ~intercepteu~ a fault gouge zone <br />(Exhibit A).~ The zone was first penetrated in 2L entry and <br />the material within the zone consisted of pulverized coal, <br />soft, wet clay, and clayey shale. The material is quite <br />incompetent and tends to fall into the entry unless extensively <br />supported. The intercepted zone produced water which increased <br />the total flow of water into the mine workings. <br />The fault had been predicted by surface geologic mapping, <br />but due to the inaccuracies in mapping, was encountered <br />somewhat earlier than expected. S•7hile plans were made to <br />cross the fault, an operating unit turned southward with <br />plans to drive until the fault was encountered and pillar <br />back to maintain production. <br />Prior to encountering the fault, water production into th~ <br />No'. 5 Mine vii. 2~, West Ma,iTis„,was.. minimal. Upon encounteri <br />thy, ~au1t,~ wat,e,~ p~o~luctioi~~l,ncreased t4 an estimated' stead <br />state condition of about 110 gpm. On or.apout 1/25/821 th~ <br />fault was crossed and mining begun betoreen the faults ,z <br />Water production from the 2 West area increased to 448 npm~ ' <br />On February 20, 1982, a second fault was encountered about <br />490 feet inby the former fault. <br />scope <br />On March 2, 1982, Cyprus Coal Company was asked to provide <br />technical assistance to determine fault displacement and <br />project mining concerns resulting from fault interception, <br />the source of water associated with the first fault, and the <br />possibility of encountering additional faults as mining <br />continues. J&L Drilling, Inc., of Montrose, Colorado, was <br />contracted to conduct an underground drilling program to <br />retrieve core samples of the roof and floor lithologies to <br />assist in the determination. Underground mapping was conducted <br />with special emphasis toward noting changes in water inflow <br />through time, noting changes in cleat orientation, and <br />locating sandstone intrusions that might be predictive of <br />faulting. <br />Setting <br />The Eagle No. 5 mine operates in the F seam within the lower <br />portion of the Cretaceous Williams Fork Formation. However, <br />-1- <br />