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4.0 MOFFAT STABILITY MONUMENTS <br />A system of three control points and six monuments were established in the final Moffat pit area <br />during the fourth quarter of 1997. The purpose of the monuments is to monitor the hillslope for <br />long -term stability. The three control points were placed to form a large triangle. The reference <br />control point was established along the top of the hillside in undisturbed ground above the final <br />Moffat pit. The two additional control points (back- sites) were established in undisturbed ground <br />northwest and south of the reference point. The back -sites were established to verify the location <br />of the reference point. The monuments were installed in pairs with the first pair, SM -1 and SM- <br />2, established in the lower third of the final pit area. SM -1 was placed approximately 130 feet <br />south of the final pit highwall and SM -2 was placed approximately 340 feet south of the final pit <br />highwall. The second pair, SM -3 and SM -4, were installed approximately mid -way along the pit. <br />SM -3 was placed approximately 110 feet south of the highwall and SM -4 was placed <br />approximately 325 feet south of the highwall. The last pair, SM -5 and SM -6 was installed in the <br />upper third of final pit area. SM -5 was placed approximately 150 south of the highwall and SM- <br />6 was placed approximately 350 feet south of the highwall. The monuments consist of T to 8' <br />sections of 2 -1/2" diameter drill steel driven 5 -1/2' to 6 -1/2' into the pit backfill material (Plate <br />3). <br />The monuments were surveyed quarterly the first year and annually thereafter. The 2011 stability <br />monument survey was performed August 11, 2011 (Table 4). <br />" VVCENGINEERING <br />Page 5 <br />