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III IIIIIIIIIIIiilll <br />DEPARTMENT OF NATURAL RESOURCES <br />David H. Getches, Executive Director <br />MINED LAND RECLAMATION DIVISION <br />DAVID C. SHELTON, Director <br />Richard D. Lamm <br />Governor <br />DATE: March 5, 1986 <br />T0: Gregg Squire ~ ~,-~-- <br />FROM: Jim Pendleton' "`- <br />RE: DECEMBER, 5 SEM NUAL SUBSIDENCE MONITORING REPORT, EAGLE #5 MINE, <br />LONGWA AREA -81-044) <br />Pursuant to your request, I have reviewed the above references report, which <br />presents the results of June, September and December, 1985 subsidence <br />monitoring surveys performed above the Utah trect longwall mining activity. <br />The survey and report are acceptably completed. <br />The results to date have determined a maximum vertical subsidence of 6.11 feet <br />above longwall Panel No. 1 within the Utah trect. This compares with a <br />projected maximum vertical subsidence of 8.0 feet above Pane'I No. 1. Ground <br />surface cracking has been observed above the advancing longwi~ll panel face. I <br />recommend that you attempt to inspect and document (photograph) the nature and <br />magnitude of the ground surface cracking when snow cover conditions will <br />allow. Also, carefully inspect the old spoil slopes for any evidence of <br />instability. <br />The angle of draw observed to date has varied in relation to the bedrock dip. <br />This may be affected by the presence of the previously mined surface spoils <br />above the longwall panels. The subsidence monitoring has determined an angle <br />of draw of 15.50 downdip from the gob, less than Oo (vertical) updip from <br />the gob and 14.50 behind the gob. Additional propagation of trough <br />subsidence may occur with time, which would cause maximum vertical subsidence <br />and angles of draw to change during the next year. <br />The report is acceptable as submitted. In the future, however, it would be <br />helpful if the operator would include a brief text comparison of their <br />projected maximum subsidence and angle of draw vs. that observed by the <br />monitoring. The purpose of the monitoring reports is to del;ermine whether the <br />original permit application projections were correct. Please inform the <br />operator of this report request. <br />/vjr <br />cc: Michael Long <br />8163E <br />423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 8663567 <br />