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1.0 INTRODUCTION <br />CEC initiated the subsidence monitoring plan for the E-seam workings of the Eagle <br />Mine No. 6 in November 1989. This monitoring was performed in accordance with <br />the plan approved the Colorado Mined Land Reclamation Division. This report <br />summarizes the survey schedule for and results of subsidence monitoring for the <br />1 East and 2 East longwall panels in the E-seam at the Cyprus Empire Corporation <br />(CEC) Eagle Mine No. 6. <br />Monitoring point locations are shown on the map sheet titled, "E-seam Subsidence <br />Monitors". This map sheet also shows mine workings, monthly longwall mining <br />advance, surface topography and overburden thickness. <br />Subsidence profiles are shown for subsidence lines B, C, K, 0, J, S, and T. <br />These subsidence profiles show pre-mining surface profiles, post-mining profiles <br />for F-seam mining and current surface profiles resulting from ongoing E-seam <br />mining. <br />The results of the surveys shown on the profiles in this report are tabulated in <br />Appendix A. <br />2.0 SURVEY SCHEDULE <br />The first quarterly monitoring survey was performed in November 1989. Subsequent <br />quarterly monitoring was performed during July 1990, September 1990, and <br />December 1990. <br />In November 1989, approximately one month prior to commencement of longwall <br />extraction within the 1 EAST PANEL and prior to the longwall having advanced to <br />within 800 feet of monument T-2; existing monuments K-1 through K-16 (including <br />0-1 and 0-2), S-1 through 5-27 (including T-1 and T-2), and J-1 through J-22 were <br />surveyed. <br />In July 1990, after the 1 EAST PANEL longwall had advanced past the S-J row; <br />monuments K-1 through K-16 (including 0-1 and 0-2), R-12 through R-30, S-1 <br />through 5-27 (including T-1 and T-2), and J-1 through J-22 were again surveyed. <br />Additionally, prior to mining within 600 feet of monument C-13, existing <br />monuments C-1 through C-13, and B-1 through B-18 were surveyed. <br />In September 1990, eight additional monuments, B-O1 through B-08, were installed <br />to extend the "B" Row of monuments the full width of the 2 EAST PANEL. These new <br />points were surveyed in September 1990 to establish initial coordinates and <br />elevations. <br />In December 1990, upon completion of the 1 EAST PANEL, all monitoring points <br />projected to lay within the subsidence zone of influence of the 1 EAST PANEL were <br />surveyed. <br />Cyprus Empire Subsidence Report <br />February 23, 1991 page 1 <br />