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<br />> program we regulate coal mining in the state. There is a reclaimed coal mine <br />> located north of the town of Meeker (Meeker Area Mines). The operator of the <br />> mine has submitted a revision to reconstruct Curtis Creek (they previously <br />> diverted the drainage around a series of sediment ponds). The reconstructed <br />> channel will pass through the sediment ponds. Our rules require that the <br />> emergency spillway can safey pass the 25-year, 24-hour storm event. The peak <br />> flow for the 25-year event is roughly 600 cfs. The 100-year event is over <br />> 2000 cfs. <br />> The problem that we face is that there are rougly 50 detention basins in the <br />> 9 square mile water shed. The 600 cfs number did not take these ponds into <br />> consideration due to the time it would take to model each pond. I am looking <br />> for any research that has been done that documents effects of small <br />> structures on peak flow. I did find some research done in Texas which <br />> concludes that if a pond has an emergency spillway, the peak discharge is <br />> reducted by appx. 508 due to the effects of spillway storage in the pool. <br />> When there is no spillway flow, the reduction in peak discharge is about 988. <br />> I appreciate your help in this matter. If you have any questions, I can be <br />> reached at 866-3567. <br />> Sincerely, <br />> Erica S. Crosby <br />> Environmental Protection Specialist <br />- ------- End of Forwarded Message <br />