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.~ <br />Grand Mesa <br />~~~ ~ Coal Company <br />July 30, 1985 <br />Mr. Thomas Gillis <br />Reclamation Specialist <br />Colorado Mined Land Reclamation Division <br />423 Centennial Building <br />1313 Sherman Street <br />Denver, Colorado 80203-2273 <br /> <br /> <br /> <br />Subject: File i1C-034-81 - Subsidence Monitoring <br />Dear Tom: <br />First and Columbia <br />P. O. Box 226 <br />Delta, Colo. 81416 <br />Otfice: (303) 874-7561 <br />Mine: (303)856-6402 <br />The permit dated July 13, 1984 requires that GMCC monitor subsidence quarterly <br />with reports sent to the Division semi-annully. This is the first subsidence <br />monitoring report. <br />The installation of the subsidence monuments and the original base line survey <br />was completed early in 1982. This first subsidence monitoring survey was done <br />in June 1985 by Ute Engineering of Delta, Colorado. The survey was done on selected <br />points that are within the area of influence of the underground workings. The <br />following table shows the original survey data, the June 1985 survey results, <br />the apparent change in elevation and the relative change in elevation. . <br />SUBSIDENCE INITIAL JUNE 1985 CHANGE IN RELATIVE BACK <br />POINT ELEVATION ELEVATION ELEVATION CHANGE IN ELEVATION SITE <br /> <br />Sta 3 6551.21 6551.21 <br />Sub-K 6534.71 6534.43 -0.28 -0.28 Sta 3 <br />K-2-1 6539.57 6538.90 -0.61 -0.39 Sub K <br />K-2-2 6539.19 6539.27 +0.08 +0.36 Sub K <br />Sub 0 6563.24 6563.18 -0.06 -0.06 Sta 3 <br />0-8-1 6554.17 6554.10 -0.07 -0.01 Sub 0 <br />0-8-2 6554.03 6553.96 -0.07 -0.01 Sub 0 <br />Sub R 6480.44 6479.54 -0.90 -0.24 Sub Q <br />R-6-1 6497.67 6496.81 -0.86 +0.04 Sub R <br />R-6-2 6494.76 6493.87 -0.89 +0.01 Sub R <br />Sub Q 6466.81 6466.15 -0.66 -0.66 Sta 3 <br />Sub S 6576.06 6575.34 -0.72 -0.06 Sta Q <br />5-7-1 6566.35 6565.63 -0.72 -0.00 Sta S <br />5-7-2 6566.64 6565.91 -G.73 -0.01 Sta S <br />