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COLORADO <br /> Division of Reclamation, <br /> Mining and Safety <br /> Department of Natural Resources <br /> February 25,2020 <br /> Tom Bird <br /> GCC Energy,LLC <br /> 6473 County Road 120 <br /> Hesperus, CO 81326 <br /> Re: King Coal Mine,Permit C-1981-035, <br /> Second Review of the 2018 Annual Hydrology Report <br /> Dear Mr. Bird: <br /> The Division received the 2018 AHR for the King Coal Mine on December 31,2018. I reviewed this <br /> AHR in the context of Rules 4.05.1,4.05.6,4.05.11,and 4.05.13 and sent a letter with my comments on <br /> January 2,2020. GCC Energy sent a Technical Memorandum by Resource Hydrogeologic Services <br /> (RHS) addressing my comments, and the Division received this on February 14t''. <br /> While in general RHS provided sufficient responses to my comments and also provided <br /> interesting and relevant background information,I do have the following additional <br /> comments/requests: <br /> 1. Based on correspondence with personnel at the Colorado Water Quality Control Division,water <br /> quality standards are not applied differently to water imported from another basin. Therefore,the use <br /> of Regulation 34 standards for surface water is appropriate,in my opinion, for an initial assessment of <br /> potential impacts from the mine. In the future, should exceedances be detected,further analysis <br /> could be conducted to assess potential sources of high concentrations and potential impacts on <br /> the receiving water(Hay Gulch). These analyses might entail spatial analyses(with consideration <br /> of concentrations in the ditch above the mine) and temporal analyses(changes since baseline). Also, <br /> site-specific conditions should be considered,including water consumption records and discharges <br /> from the Mormon Reservoir. All of this information should be taken into account. <br /> 2. In my initial review of the 2018 AHR,I said that high pH values in bedrock wells are possibly caused <br /> by mining activity. The response by RHS states that"... low specific conductance may actually lend <br /> some of the pH variability through sensitivity which comes in dilute water with lack of buffering." <br /> Please provide more explanation. It is the Division's opinion that alkalinity is a better indicator of <br /> buffering capacity than specific conductance. Also,it is our opinion that buffering capacity does not <br /> entirely explain the cause of pH fluctuations. <br /> 3. In my initial review of the 2018 AHR,I said that high sulfate concentrations in down gradient alluvial <br /> wells are possibly caused by mining activity. Upon further investigation,data for the Wiltse well <br /> from old AHRs (e.g.,the AHR sent to the Division in July 1994)indicated high concentrations of <br /> sulfate,generally from 800 mg/l to 1,200 mg/l, from 1982 to 1984. This data illustrates that recent <br /> King Coal operations are not causing a deterioration of water quality in this well.No additional <br /> I I� o <br /> 1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us * <br /> \ <br /> *' <br /> Jared S. Polis, Governor Dan Gibbs, Executive Director Virginia Brannon, Director JR?6*'/r <br />