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Survey data confirms that actual measured surface subsidence effects are well <br />within or less than both the maximum expected subsidence and the angle of draw <br />predictions. In addition, recent measured incremental deflections for any of the <br />monuments, are of very limited magnitude, 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 <br />of this is shown on Table 1, High-Reso/ution Grid Survey Data, and in graphic <br />format on attached Figure 22, Subsidence History/Maximum Subsidence, High <br />Reso/ution Grid. These data show the correlation between subsidence and mining <br />history. Retreat mining of the panel (2 South-'A' Panel} directly under the <br />monument grid occurred from April through June 1983. Subsequent retreat <br />mining of the adjacent panel (2 South-'B' Panel), underlying Monuments SO <br />through 15, occurred from June through August 1985. These dates mark the final <br />mining in areas potentially impacting the high-resolution grid. <br />A final subsidence survey during year 9 (2012) of the reclamation liability period <br />will include the high resolution grid. This survey is designed to confirm and <br />document long-term surface subsidence effects. The 23 monuments of the high- <br />resolution grid will not be removed unless approved by the Division. <br />A total of 11 monuments have been monitored on a quarterly basis. These <br />monuments are as follows: <br />City of Florence Waterline (8 monuments) <br />Thompson Ranch Structures (3 monuments) <br />In addition, one monument has been monitored on asemi-annual basis, as <br />follows: <br />Newlin Creek Streambed (1 monument) <br />The locations of all subsidence monuments are shown on the Mine Plan Map, <br />(Map 17). <br />TR-36 2.05.6-60 Revised -October 2003 <br />