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III IIIIIIIIIIIIIIII 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1313 Sherman 51.. Room 215 Denver, CO 80203 Phone: 17071 866 3 567 fA%: (3071 83 2 81 06 February 23, 1994 of cow ~~, .~ „ / re T6 ~ Roy Romer Governor Mlc hael B. long Divrsion Dvttmr Attn: Al Weaver Enerqy Fuels Coal, Inc. P.O. Box 449 Florence, CO 81226 Re: Semi-Annual Subsidence Report Review, May 1993-October 1993 Southfield Mine (C-81-014) Dear A1: The Division has received your Semi-Annual Subsidence Report for May 1993 to October 1993. All items have been appropriately addressed and the subsidence data is within permit allowances. The measured angle of draw appears to be 26 degrees which is the upper limit allowable by current permit standards. The Division and EFCI are currently in the process of revising the subsidence maximum angle of draw to 26-29 degrees as part of the permit renewal and response to Stipulation No.21. In this report, there are no indications of exceedences in either the angle of draw or total vertical subsidence allowable. The report also included two cross-sections of the north-south and east-west subsidence high- resolution grid per permit requirements. All structures monitored show zero to minimal subsidence cumulatively and within the last year. All structures remain sound. No material damage has been recorded since monitoring began in 1983 and in 1985 with the high-resolution subsidence grid. The Division would like to remind EFCI that in the process of increasing the angle of draw during the permit renewal period, that any increased areas be surveyed for structures or renewable resource lands. This concludes the Division's review. The Division finds the Semi- Annual Subsidence Report for May-October 1993 to be complete and within compliance of the regulations. Sincerely, ~~. ~Sh~wn E. Sm}'th Environment rotection Specialist ses/subside.94