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• iii iiiiiiiiiiiu iii United States Department of the Interior I N REPLI' REFER TO OFFICE OF SURFACE MINING Reclamation and Enforcement 1999 Broadway, Suite 3320 Denver, Colorado 80202-5733 May 21, 1997 RECEI\/ED MAY 2 7 1997 Division of wuneiais 6 ~doioyy David A. Berry Senior Environmental 1313 Sherman Bldg., Denver, CO 80203 Dear Mr. Berry: Protection Specialist #215 Ox:ow Carbon an3 Minerals, Inr__ proposed (Technical Revision 29 dated February 28, 1997) to mine coal at its Sanborn Creek Mine on Federal coal lease COC-53510 using the longwall mining method to mine up to 4 million tons of coal per year rather than the currently approved room-and-pillar method which produces coal at 1.3 million tons per year. The Colorado DMG contacted OSM in March 1997 to discuss whether such a change in maximum annual coal tonnage and the resultant water depletion from the Colorado River Basin would necessitate a mining plan modification. The application included a mine water depletion analysis conducted in accordance with the Windy Gap Process. That analysis indicated less water (83.2 acre-feet per year) would be depleted from the Colorado River Basin using the longwall method than would be depleted using the room-and-pillar method (85.5 acre-feet per year). OSM reviewed the depletion estimate from a mining engineering perspective and agreed with the assumptions made by the operator in arriving at the revised depletion allowance. OSM determined that since the revised depletion estimate of 83.3 acre-feet per year was less than the 93.2 acre-feet per year currently approved during consultation with USFWS in September 1996, no further consultation was required with USFWS on this matter. If you have any questions, please call me at 844-1499. Since ly, Lawrence G Kline Project Manager Colorado Federal Lands