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~~ ~ Ener V ~/ March 14, 2005 Mr. Jeff Coombe Colorado Dept. of Public Health and Environment Water Quality Control Division 4300 Cherry Creek Drive South Denver, CO 80222-1530 Colowyo Coal Mine 5731 State Highway 13 Meeker, Colorado 81641 Telephone: (970) 824-1531 Fax: (970)824-1598 Kurtis R. Blunt Environmental Technic iari RE: EVALUATION OF THE STATUS OF OUTFACE 005A (STOKER SIDING POND) FLUME AND RECOMMENDED COURSE OF ACTION TO RE-ESTABLISH FLOW MEASURING FUNCTION DURING FUTURE DISCHAGE EVENTS. Dear Mr. Coombe, Colowyo Coal Company L.P. (Colowyo) is responding to the conversation between the environmental staff at Colowyo and yourself on March 11, 2005 regazding the status of the Parshall Flume associated with the Stoker Siding Pond. There has been a gradual buildup of cattails and sediment in the area immediately down-drainage from the Stoker Siding Pond Flume since the pond was established. In an attempt to restore proper function of the flume, the azea immediately around the structure and to the edge of the current permit boundary was cleaned out in December, 2004. Subsequent snow melt and intermittent low level discharges from the pond have resulted in a ponding condition surrounding the flume. As a result, accurate measurement of discharge from the Stoker Siding Pond is difficult to obtain. There are two possible courses of action that will restore proper function of the flume: 1) Obtain the necessary permission and permitting to remove the buildup of cattails and sediment down-drainage from the flume outside the current mine permit area. 2) Raise the elevation of the flume and associated structure components through excavation and refitting; and re-engineer the pond, and SEDCAD information to reflect the changes. In order for the cleanout to produce satisfactory long-term results, Colowyo would have to work outside the permit boundary. Approximately 200 feet of the drainage will be affected. The drainage segment between the Stoker Siding Pond Flume and the confluence of Wilson Creek is approximately 200 feet and nearly level. This particular solution could be implemented relatively quickly once the necessary permit requirements are met. Raising the elevation of the flume itself would require some engineering and modification to the embankment and spillway of the pond. This solution would require more time and effort, in addition to potentially weakening the pond embankment in the area where the discharge piping would be exposed and refitted. .~ . /~Kennecott Antelope Mine •Colowyo Mine • Cordero Rojo Mine • Jacobs Ranch Mine • Spring Creek Mine A member of the Rio Tinto Gxoup