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~_ iiiiiiiuiiiiiiiiii 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Deparlmenl of Natural Resources 1313 Sherman 51.. Room ?15 DIVISION O F Denver, Colorado 80?03 Phone: 1303) 866-3567 MINERAL S FAX: 1303) 83bB106 & GEOLOGY RECLAMATION MINING•SAFETY Internal Memorandum Bil I Owcns TO: Joe Dudash Governor CC: Larry Routten CreR E. Watcher Eee<unve Do-e<lor FROM: Sandy Brown Michael8 Long DATE: November 8; 1 9 Di~sion Direclnr RE: Oxbow Mining Inc., Sanborn Creek TR-32 I reviewed the soils, vegetation, topsoiling and revegetation plans for this TR. I based my review on Oxbow Mining Inc.'s original submittal dated October, 1998 and item numbers 3, l4 and l9 in their August 25, 1999 submittal. My comments are below. This memo is on the M drive if you want to use i[ later. Soil Resources -Rule 2.04.9 The cover letter says that the disturbance in the Elk Creek Mine surface facilities falls within the mapped boundaries for the Torriorthents-Rock Outcrop, sandstone complex. Map 2.04-M7 does not show the disturbance boundary, but it appears that part of the disturbance may also be in Absarokee -work loam. Please clarify. The Torriorthents-Rock Outcrop, sandstone complex has been described previously in soil surveys for other parts of the mine. The DMG agrees there is enough available information to determine the soils suitability as a growth medium with one exception. Two soil samples are shown on Map 2.04-M7 in Elk Creek, ECS-l and ECS-2. The top twelve inches of each sample was analyzed. The results show the texture of both these samples is clay. Will the clay limit the soils usefulness for reclamation? The depth of topsoil to be salvaged is not addressed. Were depth measurements taken at the two sample locations? As stated in the letter there are significant variations in soil thickness dependent on a number of factors including topography, aspect, drainage and other considerations. It is necessary to have some idea as to the depth of soil material to be salvaged as a result of mine development in Elk Creek. Please discuss the controlling factors in Elk Creek and what the anticipated, or measured, topsoil depths will be based on these factors. Soil depths are needed to determine topsoil mass balance. OM[ has committed to recover up to a maximum depth of four feet of topsoil. DMG needs to know how much topsoil is available before this can be approved.