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., <br />Mr. Terrell Johnson - 2 - June 17, 1991 <br />The purpose of these monuments shall be as a supplement for the underground <br />pillar stability monitoring program conducted by the operz~tor. These <br />monuments shall be installed and initially surveyed twice prior to mining <br />advancing to within the area possibly affected by the angle of draw of 20 <br />degrees from vertical. Following initial installation and surveying, these <br />monuments shall be monitored annually and reported within the annual <br />subsidence monitoring report. If the underground pillar stability inspection <br />is curtai+ed the surface monument monitoring frequency shall be increased to <br />twice a .year. Monitoring shall continue until cessation is approved in. <br />writing by the Division. The operator shall also briefly summarize the <br />results of their underground pillar observation studies within the annual <br />subsidence monitoring report. <br />As .you know, the Division is required to render a decision on this matter on <br />or before August 2, 1991. To allow for review time, pleasfa have adequacy <br />responses to our offices prior to July 22, 1991. <br />If .you have any Questions, please contact me. <br />Sincerely, <br />Carl B. Mount <br />Reclamation Specialist <br />CBM/yjb <br />6436E <br />