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_~ `` Richartl D. Lamm Governor _ - - DEPARTM• OF NA III III'lllll"II II~ ~ D. Moore Pascoe. Executive Duer,Nr MINED LAND RECLAMATION DIVISION DAVID C. SHELTON Director March 1, 1983 Mr. Henry Barbe Powderhorn Coal Company P.O. Box 1430 Palisade, Colorado 81526 Re: Surface Water Monitoring and Contingency Plans F11e No. C-041-B1; Roadside and Cameo Mines Dear Mr. Barbe: The Division has completed its review of your responses to Stipulations No. 4 and 5. The plan for monitoring surface water flows 1n Rapid Creek and Cottonwood Creek is acceptable to the Division, with one exception. The plan submittd indicates that a nine-inch Parshall flume "may" be added to station SWGS-Ol. The existing four-foot flume is rated to measure flow down to 1.3 cfs, but low flows at the site are below 1 cfs during late summer. Since mining activities are more likely to affect low flows, the smaller flume must be installed. It is the Division's understanding that this 1s acceptable to Powderhorn. In addition, as we discussed in a phone conversation on February 28, 1983, the Division has no problems with Powderhorn installing crest-stage gauges at the monitoring sites on Rapid Creek and Cottonwood Creek. It is the Division's understanding that the monitoring plan will be revised to Include the crest-stage gauges. The contingency plan to install a corrugated metal culvert to convey flow past an affected reach of stream is an acceptable temporary solution. However, because culverts require frequent maintenance, it may not provide a permanent solution following the cessation of operations. Possible permanent solutions include requiring a plan of augmentation or constructing a lined channel. Other solutions may also be possible. It is difficult to design an acceptable permanent solution without having identified the specific problem to be solved. ihe_opera.tor_ should .rewrite the contingency plan to indicate that a corrugated metal culvert would be installed in a timely manner as a temporary solution, and that the operator would then consult with the Division and would provide an appropriate permanent solution for the problem. The revised contingency plan should identify alternative water supplies that could be used, if necessary. 423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567