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RMG report as the subsidence plan for the Southfield Mine, with the only exception <br />• being reduction in monitoring frequencies, and elimination of monitoring the high- <br />resolution grid. The RMG report and EFCI's supporting monitoring data are included <br />in this section and in Exhibit 23, Subsidence Information. <br />Monitoring is no longer necessary at the high-resolution ("South") subsidence grid. <br />Subsidence observed at the high-resolution grid, as documented by Semi-Annual <br />Subsidence Reports from 1983 through 1995, has verified the subsidence predictions <br />made by RMG. Survey data, through the latest monitoring period, confirms both the <br />maximum expected subsidence and the angle of draw predictions. In addition, only <br />small deflections are occurring at any of the monuments corresponding to material <br />consolidation rather than subsidence. <br />Incremental subsidence of the South subsidence grid monuments has decreased <br />rapidly beginning in 1986, and has almost ceased to occur since 1992. Evidence of <br />this is shown on Table 1,High-Resolution Grid Survey Data, and in graphic format on <br />attached Figure 22, Subsidence History! Maximum Subsidence, High Resolution Grid. <br />These data show the correlation between subsidence and mining history. Retreat <br />• mining of the panel (2 South-'A' Panel) directly under the monument grid occurred <br />from April 1983 through June 1983. Subsequent retreat mining of the adjacent panel <br />(2 South 'B' Panel), underlying Monuments 10 through 15, occurred from June 1985 <br />through August 1985. These dates mark the cessation of mining in the areas <br />potentially impacting the high-resolution grid. <br />The 23 monuments of the high-resolution grid will not be removed unless approved <br />by the Division. These monuments will be resurveyed before bond release is <br />completed for the area containing the monuments. <br />A total of 11 monuments will be monitored on a quarterly basis. These monuments <br />are as follows: <br />City of Florence Water Line (8 monuments) <br />Thompson Ranch Structures (3 monuments) <br /> <br />2.05.6-60 Revised 223/96 <br />Technical Revision No. 24 <br />