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IX. MOFFAT STABIL[TY MONUMENTS <br />A system of three control points and six monuments were established in the final Moffat pit area during the fourth <br />quarter of 1997. The puryose of the monuments is to monitor the hillslope for long-term stability. The three control points <br />were placed to form a large triangle. The reference control point was established along the top of the hillside in undisturbed <br />ground above the final 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 of the reference point. The <br />monuments were installed in pairs with the first pair, SM-1 and SM-2, established in the lower third of the final pit area. SM- <br />I was placed approximately 130 feet south of the final pit highwall and SM-2 was placed approximately 340 feet south of [he <br />final pit highwall. The second pair, SM-3 and SM-4, were installed approximately mid-way along the pit. SM-3 was placed <br />approximately 110 feet south of the highwall and SM-4 was placed approximately 325 feet south of the highwall. The last <br />pair, SM-5 and SM-6 was installed in the upper third of final pit area. SM-5 was placed approximately I50 south of the <br />highwall and SM-6 was placed approximately 350 feet south of the highwall. The monuments consist of 7' to 8' sections of Z- <br />1(2" diameter drill steel driven 5-1(2' to 6-l /2' into the pit backfill material. <br />The monuments are to be surveyed quarterly the first year and annually thereafter. In 2003, a level loop was <br />surveyed providing elevation information. However, due to an equipment malfunction, x and y coordinates were lost. The <br />coordinates of the initial monument survey and subsequent surveys are provided in Appendix E. <br />' X. <br />TROUT CREEK SANDSTONE <br />Monitoring of Well TCS-1 was initiated in 1995 to ensure [he absence of mining impacts on the Trout Creek <br />Sandstone aquifer. Results of the monitoring efforts are provided in Appendix F. To date, no impacts from mining activity <br />are evident in Well TCS-l . TCS-1 was not sampled in 2004 due to equipment problems. <br />49 <br />