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Environmental Protection Plan-Amendment M <br /> Permian Cutler Formation Base of San Juan Basin <br /> Rico Formation <br /> Pennsylvanian Hermosa Formation <br /> Ore-bearing veins are north-trending and mainly found within the Junction Creek, <br /> Sandstone,Wanakah Formation and Entrada Sandstone(Eckel, 1949).As can be seen from <br /> the above table,the ore-bearing veins are below the highest water producing aquifer. <br /> There is little published information regarding groundwater conditions in the vicinity of the <br /> mine site. A review of well permits within 2-miles of the mine entrance(Figure U-2) <br /> indicates that most wells are located either within the alluvial material associated with La <br /> Plata River,sandstone(presumed to be the Morrison Formation)north of the fault system <br /> or the Mancos Shale south of the fault system. A summary of domestic well permits and <br /> relevant geological information is presented in Attachment U-2.Detailed hydrogeologic <br /> and geochemical data area presented in Exhibit G-Water Information. <br /> A discussion with Dr. David Gonzales,Fort Lewis College, who is familiar with the <br /> underground workings within the permit area, suggests that the groundwater is contained <br /> within fractured systems of the sedimentary host rocks. This has been determined based on <br /> observations of the presence of water within the underground mine workings. <br /> The two mine drifts believed to be flooded are Levels 423 and 545 at approximately 8,300 <br /> feet AMSL(Dr.David Gonzalez,pers.comm.). The drifts are located within the Entrada <br /> Sandstone south of the May Day Fault,and in the absence of other data,this is considered <br /> to be the level of the saturated zone in this portion of the permit area. <br /> A cross-section presented by the Colorado Geological Survey is prepared for the mine area <br /> (Kirkham et. al.,2000)and is reproduced in Figure U-3. Based on the interpretation <br /> presented by Kirkham et. al. (2000),the Entrada Formation is exposed in the Idaho <br /> Operational Area. <br /> References <br /> Eckel,E.B. (1949) Geology and Ore Deposits of the La Plata District Colorado. U.S. <br /> Geological Survey Professional Paper 219. <br /> Kirkham,R.M.; Gonzales, D.M.;Poitras,C.; Remley,K. and Alen, D. (2000) Geologic <br /> Map of the Hesperus Quadrangle, La Plata and Montezuma Counties, Colorado. Colorado <br /> Geological Survey Open File Report 00-4. <br /> Topper, R, Spray,K.L., Bellis, W.H., Hamilton,J.L. and Barkmann,P.E. (2003) <br /> Groundwater Water Atlas of Colorado. Colorado Geological Survey Special Publication 53. <br /> (c) Site Geologic Media <br /> Exhibit U-EPP Amendment <br /> 112d-M-1981-185 <br /> May Day Idaho Mine Complex <br /> March 10,2017 <br /> Page 16 <br />