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~ III IIIIIIIIIIIIIIII ~ <br />51~TE OF COLORADO <br />Roy Romer, Govei <br />DEPARTMENT OF NATURAL RESOURCES <br />MINED LAND RECLAMATION DIVISION <br />DAYID C. SNELTON, Director <br />May 26, 1987 <br />Mr. Rick Mills <br />Twentymile Coal Company <br />29515 Routt County Road 27 <br />Oak Creek, Colorado 80467 <br />Re: 198 Annual Hydrologic <br />File No. C-82-056 <br />Dear Mr. Fiills: <br />Report (AHR) - Foidel Creek Piine <br />A thorough review of the Foidel Creek AHR was performed in late spring, 1987. <br />This newly formatted report documented compliance with the existing hydrologic <br />monitoring plan from the November, 1983, permit application. Spot quality <br />assurance checks of analytical sites did not disclose any laboratory problems <br />besides inadequate detection limits for mercury. The aquatic stream standard <br />for mercury is 0.05 ug/] and the detection limit is four times higher at 0.2 <br />ug/1. In addition, field electrical conductivity levels did not compare well <br />with laboratory electrical conductivity levels. <br />The Foidel Creek Mine is impacting the hydrologic balance of the area through <br />its dewatering of the Wadge coal aquifer and the subsequent discharge to <br />Foidel Creek. Dewatering of the Wadge coal aquifer has simultaneously <br />accelerated the migration of a saline spoils plume from the adjacent surface <br />mine, resulting in mine discharge waters which reflect spoils quality, rather <br />than unaffected Wadge overburden quality. Foidel Creek, ephemeral above the <br />mine, is currently experiencing perennial discharge. <br />In 1986, mine discharge waters averaged 0.26 cfs, slightly lower than the <br />maximum projected discharge from the Foidel Creek portals of 0.278 cfs. TDS <br />levels in 1986 were similar to levels observed throughout the three-year <br />monitoring period. These waters mix with surface water runoff from the <br />adjacent surface mine, and result in a discharge which has ten percent fewer <br />dissolved solids than the mine discharge itself. Previous years, and in the <br />future, this pond will also include contributions from the Area 2 pit. This <br />pit is fed exclusively by backfilled spoils and in 1986 had TDS levels <br />approximately 1000 mg/1 higher than the mine discharge water. Consequently, <br />the quality of effluent from pond D should deteriorate once the Area 2 pit <br />begins to discharge. <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567 <br />