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• STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Depanmenl of Natural Resources 171 J Sherman 51., Room 215 Denver, Colorado 80203 Phonc. U031 866-3567 FA%:130)1 832-8106 April 18, 1994 Mr. Joe Wilcox office of Surface Mining Western support Center 1020 lsth street Denver, Colorado 80202 Re: Notes from April 15, 1994 Meeting Regarding sediment standard Comparisons - Meeker Area Mines (C-81-o32) Dear Joe: I~~~ DEPARTMENT Of NATURAL RESOURCE Nay Nomrr Goverror Ken Sala tar E.ecuave Direr mr Michael & LunN Divivon Dirermr • This letter is intended to summarize the content of our meeting on April 15, 1994 regarding the sediment standard comparisons at the Meeker Area Mines and clarify items that may have been confusing in the original submittal. Derivation of Sediment Standards The first point requiring clarification concerns the use of T values. As Greg Lewicki pointed out in the April 15 meeting, T values were discussed in Minor Revision MR-08 only as a comparison to show that the sediment loss values computed using the USLE are lower than the T values. This comparison may have been superfluous; however, the T values were not used for the sediment standards. The standards were based on the computations done using the USLE. Ali empirical sediment accumulation measurements were compared to the USLE-derived standards. Contribution of Reclaimed Areas to Sediment Ponds The OSM also expressed sediment coming from the a concern that the relationship between reclaimed areas and sediment in the ponds is not apparent, because the ponds undisturbed watersheds. The concern than-predicted sediment contribution areas draining into the ponds could from the reclaimed area that could . This, however, is unlikely, becaus reclaimed land is primarily grasses collect sediment from mostly was apparently that a lower- from the extensive undisturbed mask a sediment contribution be higher than the standard. e the vegetation type on the with no appreciable canopy,