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~_- TerraMatrix <br />Engineeri 8~ Entriromrnetital Services <br />~9 <br />165 S. Union Boulevard • Suite B00 <br />Lakewood, Colorado 80226 <br />303-736-5140•tax 303-965-3739 <br />November 18, 1993 <br />Mr. Randy Price <br />Division of Minerals and Geology <br />1313 Sherman Suite, Room 215 <br />Denver, Colorado 80203 <br />RECE11%EC <br />NOV 19 199 <br />Dit•re c~ r <br />u; ~ ~;;gY <br />III IIIIIIIIIIIII III <br />sss <br />Re: Temporary Use of Stormwater Storage for Pit Water Discharge, Kerr Coal Mine (Permit No. <br />C-80-006) <br />Dear Randy; <br />As you are aware, Kerr Coal Company (KCC) has escalated reclama[ion activities on the 720 pit and <br />overburden stockpile area. Due to these accelerated activities, KCC has started discharging water <br />from the 720 Pit into the sediment storage space of sediment pond A. KCC has applied to the <br />Colorado Department of Health (CDH) for a NPDES discharge permit for pit discharge, and <br />expetts such permit to be approved by mid-January, 1993. However, in the interim, addition <br />storage will be required, or KCC will be forced to temporarily suspend reclamation activities. <br />Given this situation, KCC is requesting a Minor Revision (MR-~ to temporally use the Stormwater <br />storage volume of ponds A, B, C, and D from now through the month of February for storage of <br />pit water. To acquire the additional storage, IkCC is proposing to temporarily plug the dewatering <br />orifices and allowing the active portion of [he ponds to fill. The ponds would be allowed to fill to <br />within one foot below the invert of the emergency spillway. At the end of February and/or upon <br />approval of the CDH discharge permit, KCC would remove the plugs and allow the pond to return <br />to the design capacities. Any released water will have to meet the requirement of the NPDES <br />permit. <br />There are no formal records as to the amount of runoff for the months of November through <br />February; however, over the past 10 years, during these months KCC has visually observed no or <br />very little runoff. Any runoff that may occur during [hese months should be safely contained in <br />the remaining one foot of storage between the proposed storage height and the invert of the <br />emergency spillway. <br />The benefits associated with this MR would be additional retention time of the pit water. This extra <br />step would allow increased settling time which would lead to less potential treatment to meet <br />effluent standards. <br />To plug the orifices, KCC will utilize either a Wing Nut Test Plug or the designed plug system <br />shown on attached Figure 1, Plug System. The Wing Nut Test Plug is a simple expandable rubber <br />plug which can be inser[ed into the orifice and expanded to seal the hole. Both Plug systems are <br />designed so that they may be easily removed. For additional protection against leakage, KCC will <br />Steamboat Spdngs, CO • Denver, CO • Seattle, WA • Juneau, AK • Santiago, Chile SA <br />