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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />CO L O R A D O <br />D I V I S I ON OF <br />Phone: (303) 866 -3567 <br />RECLAMATION <br />FAX: (303) 832 -8106 <br />M I N I N G <br />INTEROFFICE MEMORANDUM <br />SAFETY <br />John W. Hickenlooper <br />Governor <br />Mike King <br />Executive Director <br />Loretta E. Pineda <br />TO: Dan Hernandez <br />Director <br />FROM: Mike Boulay ' • 3 <br />DATE: September 10, 2012 <br />SUBJECT: New Elk Mine Permit C -81 -012, Bates Shaft Construction Clarification <br />I have reviewed the August 7, 2012 letter from Agapito Associates, Inc. (AAI) regarding the <br />Bates Shaft Construction Clarification. I have discussed the construction methodology with J.E. <br />Stover & Associates and with ECO Grouting Specialists Inc. of Ontario regarding the <br />construction approach and feasibility of the proposed grouting method for sealing off <br />groundwater inflow to the shaft. I also reviewed the general geology and hydrology of the site <br />regarding groundwater occurrence and flow direction and the potential for the project to impact <br />the Purgatoire River. Based on my review, I conclude that the plan as proposed by AAI and <br />New Elk Coal Company will be more effective at sealing potential water - bearing zones than <br />constructing a concrete liner. My conclusions and comments are provided below. <br />Site Conditions <br />The Purgatoire River and its tributaries are predominantly gaining streams. Groundwater flows <br />towards stream valleys and given the fact that the Purgatoire is gaining it can be concluded that <br />the shaft construction should not impact flows in the river. Shallow alluvial groundwater in the <br />vicinity of the shaft would flow from south to north toward the river from higher elevation to <br />lower elevation. There is very little probability for river water entering the shaft and if the shaft <br />is sealed off from groundwater inflow there should be no water depletion issues or impacts <br />otherwise. The occurrence of groundwater is limited to the shallow alluvium above the <br />underlying competent bedrock. This is verified by AAI in their letter. Geophysical logs for <br />exploration borings indicate static groundwater to range from between 25.2 to 29 ft. bgs which is <br />within 2 ft above to 6 ft below the top of bedrock surface. Specific water bearing zones were not <br />identified, however, the source of most, if not all, of the groundwater is believed to be contained <br />within the alluvium since the underground mine workings are nearly absent of <br />groundwater /groundwater seeps. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />