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TRAPPER ~ININ6 INC. • ~II ~I~~I~II~I~~~~I~ 999 December 6, 1990 CERTIFIED #P568141694 Mr. David Berry Colorado Mined Land Reclamation Division 215 Centennial Bldg. 1313 Sherman St. Denver, CO 802 Dear David: Qn Subject: ~~~ R v^~~ 1°7. Updated Culvert Inventory and Documentation Based on several inspections at Trapper Mine, it was noted that not all culverts associated with our mining project were documented in Section 4.8.1.2 of our permit, nor depicted on the appropriate map series (M9). As discussed during your inspections we have per- formed an inventory of all the existing culverts at Trapper. We are submitting this MR to update the appropriate maps and narrative sections of our permit associated with culvert suing, location and flow capability. We are submitting an updated table 4.8-1 "Haul Road Culvert Sizing" and the new Table 4.8-1a "Additional Culvert Listing" to show a complete listing of all existing culverts, haul road and non-haul road, at Trapper Mine. Additionally, we have updated page 4-173 to incorporate these changes. Table 4.8.1 Haul road culverts presented in Table 4.8.1 were sized using the hydrological models addressed in Section 4.8.1.2 (p 4-173). However, during the 1990 field inventory, it was discovered that field installation of seven (7) existing culverts were larger than the dia- meter required to handle the modeled pea flows. We are submitting a revised table to update those actual diameters and to include all existing haul road culverts. In addition, we have added a new column to clarify those culverts which are associated with undisturbed drainages, road sutface, or are not handling peak flows from storm events. Table 4.8.1a All non-haul road culverts are listed in Table 4.S.la. This table is to identify, name, quan- tify, and present the sustainable peak flow capabilities for all existing culverts that are not associated with haul roads. These culverts are a composite of premine, agricultural access, service road corridors, reclamation access or auxiliary culverts within the active mining and reclamation areas of the mine. Trapper has not inventoried all premine culverts located in our east panel. Field installation sized many of these culverts to handle the sustainable peak flows for each location. Ranchers, farmers and/or state highway engineers developed the sizing criteria for all the premine culverts within the East Panel area and Trapper has not altered those designs. P.O. Box 187 Craig, Colorado 81626 (303) 824-4401