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STATE OF COLORADO Roy Romer, Govei DEPARTMENT OF NATURAL RESOURCES MINED LAND RECLAMATION DIVISION FRED R. BANTA, Dlreetor DATE: August 26, 1988 T0: Gregg Squire FROM: Jim Pendleton ~w~ RE: Eagle Mine L ngwall A Subsidence Monitoring Report - April, 1988 1 (Permit #C-81-044) I hav fin lly reviewed the above referenced subsidence moni~r:oring report, submitte by Empire Energy on April 28, 1988. I regret that my hectic schedule has made it impossible for me to review the document earlier. As with Empire Energy's earlier subsidence monitoring, for both the Room & Pillar and Longwall areas of the Eagle Mines, this report is clear and concise. The data demonstrates, as the operator's consultant observes, that subsidence has effectively reached its maximum and appears to have stabilized in the location of the monitored subsidence monuments. Maximum vertical subsidence detected was 7.05 feet, compared to a predicted maximum vertical ground subsidence of 8.0 feet. While the permit documents predict a maximum angle-of-draw of 20.0 degrees from vertical, the observed angle-of-draw reached 19.10 degrees on the downdip side of the Gob, 14.67 degrees behind the Gob (approximately along strike), and -1.16 degrees on the updip side of the Gob. I be]ieve that the operator has done an exemplary job of monitoring subsidence occurrence above both the Room & Pillar and Longwall mined areas at the Eagle Mines complex. Further, I recommend that the operator be granted permission to discontinue further monitoring above the Longwall area with the following condition. The operator should refrain from removing the subsidence monuments at the Eaglr Mine~_in case it were desirable_to resurvey any of the monuments for any reason in the future. attachments cc: Mike Long 215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567