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STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: (303) 832-8106 <br />6 August, 2002 <br />George Patterson <br />Kerr Coal Company <br />PO Box 459 <br />Florence, CO 81226 <br />Re: Borehole Reclamation at the Ken Mine <br />Permit Number C-80-006 <br />Dear Mr. Patterson, <br />DIVISION O F <br />MINERALS <br />GEOLOGY <br />RECLAMATION <br />MINING•SA FETY <br />Bill Owens <br />Governor <br />Greg E. Walther <br />Executive Director <br />Ronald W. Canany <br />Acting Division Director <br />The Division has received Kerr Coal Company's (KCC) proposed plan for the permanent <br />sealing of the remaining exploration holes at the Kerr Mine and has the following <br />comments. <br />The abandonment procedures proposed by MWH do not appear to meet the requirements of <br />the Colorado Mined Land Reclamation Boazd's (CMLRB) permanent sealing procedures <br />(Rule 4.07 -Sealing of Drilled Holes and Underground Openings). The general approach is <br />acceptable; however, the sealing of aquifers is not adequately addressed by the proposed <br />plan. <br />Based on depth to water and well completion intervals provided on Tables 1 and 2 of the <br />Borehole Reclamaton Plan dated 29 January 2002, it is appazent that several of the deeper <br />wells exhibit artesian flow. Some of these wells aze screened in a confined aquifer and the <br />water level has risen a considerable distance above the top of the aquifer. If this is not the <br />case, then the integrity of the cement seal in the annulus has been damaged or was never <br />properly installed allowing for surface water infiltration or the potential for comingling of <br />aquifers. These wells should be properly abandoned by sealing the entire length of the hole <br />with cement. This should include both inside the PVC well casing and annulus space. <br />DMG recommends that the proposed plan be revised to specifically address the <br />permanent sealing of aquifers. CMLRB Rule 4.07.3(2) applies to any of the exploration <br />holes or wells that have been completed in aquifers. DMG requires that these wells be <br />sealed using cement or other suitable sealant by placing the sealant in the hole from the <br />bottom to within 10 feet of the surface. Utilizing heavy mud or cuttings above the cement <br />plug as proposed, would not be acceptable as a suitable sealant for these wells. Holes <br />which have multiple aquifers or bedrock aquifers not exhibiting artesian flow may be <br />