REV100172 - Laserfiche WebLink

Home Browse Search

T~ sec d '~/i~Fg~ TRAPPER ~ININ~ INC. August 31, 1998 Mr. Tom I{aldenbach Environmental Protection Specialist Colorado Division of Minerals and Geology 1313 Sherman St. Room 215 Denver, CO 80203 I III III IIIIIIIII 999 II I RECEIVED SEP ~ 1998 DIV. OF MINERALS 8 GEOLOGY Re: Permit No. C-8t-010; Technical Revision TR-79; Middle Flume Gulch Sediment Ponds Dear Mr. ICaldenbach: Please find enclosed permit materials for TR-79, Middle Flume Gulch Sediment Control Ponds. Trapper intends to constnrct the first pond of the proposed three pond system during this fall. As demonstrated by the enclosed materials, this first pond will be sufficient to control sediment from the disturbed portions of the watershed through the }•ear 2000. The second and third ponds will then be phased in as necessary in accordance with the progressive disturbance within the watershed. A conservative assumption was utilized in modeling the Middle Flume Gulch watershed in order to ensure that sufficiently sized ponds would be wnstnrcted to control runoff water quality. The entire watershed was assumed to be disturbed for purposes of the evaluation. 1n order to evaluate the year 2000 disturbance scenario, the undistufied portions of the watershed at that point in time were measured and weighted curve numbers were calculated for the affected subwatersheds to reflect this condition. The weighted curve numbers were then inserted into the base model and evaluated with Middle Flume Pond No. 3 as the only sediment wntrol sWCture. This model run indicates the No. 3 pond is sufficient to conVOl runoff given the disturbance (from both mining areas and roads) proposed through the yeaz 2000. In addition to the sediment ponds proposed under TR-79, three culverts are added with this submittal as well. Culverts A-14, SA-6B, and SA-6C have been added to Map 51, sheet 2 of 3, with the associated permit text pages modified as well. One last map change bears mentioning. The "active mining" area in the Grouse drainage has been modified to remove an error. To process this revision, the following changes must be made to our mining and reclamation permit: 1) Revised Appendix Q Table of Contents 2) Revised Table 4.8.1 (pages 4-174 and 4-174aa) 3) Revised Tables 4.8-6 (page 4-186a), 4.8-7 (page 4-190a), and 4.8-8b (page 4-222gg) 4) Revised Map M51, sheets 2 of 3 & 3 of 3 5) Add new section to Appendix Q: Section XXX[I Middle Flume Gulch Hydrologic Model P.0. Box 187 Craig. Colorado 81626 (970) 824-4401