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4 STATE OF COLCIII IIIIIIIIIIIIIIII DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1313 Sherman 51., Room 215 Denver, l0 80203 Phone: 13031 A66-356% FAX:1J0J1832-8106 February 19, 1993 Mr. Allen Weaver Energy Fuels Coal Inc. P.O. Box 449 Florence, CO 81226 Re: Adequacy Review, Technical Revision 13, Southfield Mine, C-81-014 Dear Mr. Weaver, OF opt Ne~ Oe •n~ .:,J Roy Romer Governor MiChdP~B. LOnQ, Drv¢ron Director The Division has completed its review of the information submitted in response to NOV 91-29 and in response to Stipulation 19. This information was originally submitted March 19, 1992 and April 29, 1992. The Division apologizes profusely for the delay in this review. This adequacy letter will follow the NOV C-91-29 Abatement Responses portion of the submittal. During the review, the staff noticed that precipitation amounts for the loadout area varied significantly between this submittal and the previously approved designs. This submittal utilized rainfall amounts comparable to those at the mine site. Review of the NOAA Atlas suggests that the loadout near Florence has rainfall from a 10-year 24-hour storm of 2.6" rather than the 2.8" used in this analysis. Please note that the isopluvials in "Peak Flows in Colorado" are for rainfall between May and October; the Division uses annual hyetographs. Unfortunately, the previously approved submittals utilized precipitation amounts from "Peak Flows in Colorado" of 2.2" for a 10-year 24-hour event and 2.6" for a 25- year 24-hour event. While this results in a better hydraulics situation for the submitted information, it will require EFCI to re-submit all hydraulics information for the load-out. 1. EFCI has requested that the access road leading between the wash plant and the storage bench remain without a ditch. The staff has difficulty with this concept in light of the downcutting that exists along the south side of the road, and the need to maintain a crest on the road to ensure adequate functioning of this steep stretch of road. Rule 4.03.2(1)(a) requires an operator to maintain an access road to prevent erosion and Rule 4.03.2(4) requires access roads to be designed and maintained to have adequate drainage to pass runoff from a 10-year 24-hour precipitation event. Therefore, please prepare designs and make a commitment to install a ditch in this location. 1