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JIM TRTUM 8 RSSOCIRTES TEL~71 -995-7191 May 24.9 5=16 No .007 P.08 ... `i Mr. Michael A. Osaola -2- August 12, 1883 Las Animas County Planning ^ and Land Use' Office shaft on file: We recommend you request this information from Basin Resources, Inc. directly. ~ • Regarding your request for the mine end airshaft's 'degree of angle,' we assume this to mean the associated angle of drew in relation to planned underground mine subsidence. Current documents provided in the original application estimated the average angle of drew for the entire mine to be thirty degrees. This may be changed in the future from ectue{ longwall panel monitoring data obtained In relation to the mining occurring north of Highway 12. Note, however, that the shaft itself will not cause subsidence. Subsidence occurs when coal is extracted end the overlying material falls Into the mine void. Angle-of-drew effects are associated with overburden that la not excavated directly by the operator, but rather fells into undermined openings. Alrshaft construction involves excavation of ell material from that shaft. As such, unless significant volumes of the sides of shafts collapse, there are typically no angle-of-draw effects associated with eirshaft construction. Thank you for bringing to our attention your inspection of~Mr. Joe Chevez's realdence on June 7, 1993. Should Mr. Chavez believe his house is being Impacted by underground mine subsidence, he should request an inspection from the Division per Rule 6.02.6. We would proceed accordingly at that point. We will request another copy of Basin Resources, Inc.'s Mlne Progress Map for the Golden Eagle Mine. -Once we obtain this, we will mall a copy to your offices. Upon review of our maps, we find you were correct in assessing an error on our part regarding the proximity of underground operations at the Golden Eagle Mlne to Mr. Tatum's residence. We took Resin Resources, Int.'s Structure Inventory Map that had Identified Structure No. 28, "Pink Adobe House,' to referanco Mr. Tetum's residence, based on the photos submitted by Mr. Tatum on March 29, 1993. However, we have since determined that it Is Structure No. 27, "Adobe House; that is actually Mr. Tatum's main house, and the 'Pink Adobe House' is actually Mr. Tatum's bunkhouse.. As ouch, Mr. Tetum's residence appears t0 be 382.b feet from the plan view extent of underground mine workings. Based one 6780-foot mine roof elevation, a 446-foot overburden thickness, and a 30° angle of drew, surface effects from subsidence are estimated to extend only to a distance of 248.3 feet from the workings. This places these calculated effects from subsidence at 118.2 feet short of Mt. Tatum's mein adobe structure. As such, Mr. Tetum's realdence is situated beyond the extent of any calculated effects of underground mine subsidence. We stress again, however, that the Gglden Eagle Mlne permit was approved with a condition that operations involving the construction of underground mains to access coal north of the Purgatoire River would not create a subsidence effect et the surface. 'this condition, in the form of a 50 percent extraction Ilmit l60 percent of the coal is left in place to provide structural support and to prevent subsidence from occurring), was pieced on the permit due to the Division's concern for impacts to both structures that might be ~ ~ undermined, as well es to the river and Its assoclet9d alluvial valley floor, during and after -.. .. .. _n-...w..t+Iw.,ww~HY!•.• :.i-~~..Aa.qc;w~~r~t•ww!..u.+~•,•i!•.w.l~df!:1.Y+lY~rf~