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I . <br />~~ ENGINEERING & SURVEYING COMPANY <br />BOX 874 • 443 DODGE • DELTA, COLORADO 81416 • 303-874.7593 <br />7881-92 <br />Subsidence and Slope Stability <br />• <br />• <br />May 6, 1992 <br />Mined Land Reclamation <br />423 Centennial Building <br />1313 Sherman Street <br />Denver, Colorado 80203 <br />~~ l <br />r -i`~ <br />i ~~ ~ <br />nA~ 1 ~ 199. <br />~h~~gd Lar '` ~~ <br />t~en12matinn <br />Re: Subsidence and Slope Stability Monitoring <br />Bear Coal Company <br />Bear Mine No. 3 <br />UTE ENGINEERING AND SURVEYING COMPANY has been instructed to <br />resume monitoring subsidence points U21 and U22. See attached <br />map for location. These points were set in March of 1986 and <br />were included in UTE's semi-annual subsidence surveys from the <br />spring of 1986 to the fall of 1988. In the Subsidence report by <br />UTE dated December 22, 1988 we made note that we would no longer <br />monitor U21 and U22 unless "Specifically directed to monitor them <br />at some future date" (page 6, December 22, 1988 report). <br />On May 5, 1992 UTE surveyed U21 and U22. This survey is based <br />upon the control stations D-11-U and D-12-U that UTE Engineering <br />has used for all subsidence reports dating back to August of <br />1985. <br />The following table shows the values for subsidence points U21 <br />and U22 from 1986 through 1988. <br />STATION U21 <br />August, 1985 <br />July, 1986 <br />November, 1986 <br />July, 1987 <br />October, 1987 <br />June, 1988 <br />November, 1988 <br />Mean <br />Northing <br />Not tied in this <br />402,199.11 <br />402,199.03 <br />402,199.84 <br />402,199.82 <br />402,199.78 <br />402,199.68 <br />402,199.78 <br />Fasting <br />Survey <br />1,439,434.26 <br />1,439,433.98 <br />1,439,434.09 <br />1,439,434.22 <br />1,439,434.16 <br />1,439,434.18 <br />1,439,434.16 <br />Elevation <br />6689.58 <br />6687.971 <br />6687.08 <br />6687.24 <br />6687.14 <br />6687.13 <br />6687.152 <br />-------------------- <br />1. Tied by triangulation-No distances <br />2. Mean valves do not include July, 1986 and November, 1986. <br />There appears to be a shift in position after November 1986 <br />1 <br />