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IX. MOFFAT STABILITY 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 purpose of the monuments is to monitor the hillslope For long-term stability. The three control points <br />were placed to form a large triang]e. 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. <br />SM-1 was placed approximately 130 Feet south of the final pit highwall and SM-2 was placed approximately 340 feet south <br />of the final pit highwall. The second pair, SM-3 and SM-4, were installed approximately mid-way along the pit. SM-3 was <br />placed approximately 110 fee[ south of the highwall and SM-4 was placed approximately 325 feet south of the highwall. <br />The last pair, SM-5 and SM-6 was installed in the upper third of final pit area. SM-5 was placed approximately ] 50 south of <br />the highwall and SM-6 was placed approximately 350 feet south of the highwall. The monuments consist of T to 8' sections <br />of 2-I/2" diameter drill steel driven 5-1/2' to 6-I/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 [o an equipment malfunction, x and y coordinates were lost. The <br />coordinates of the initial monument survey and subsequent surveys aze provided in Appendix E. <br />' X. TROUT CREEK SANDSTONE <br />Monitoring of Well TCS-1 was initiated in 1995 to ensure the 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-1. TCS-1 was not sampled in 2004 due to equipment problems. The demolition of an adjacent <br />house removed power from the site. During demolition the well sustained damage. Sampling was attempted using a <br />generator but the well was deemed not functional. TCS-1 was refurbished in the fall of 2005 and sampled on 10/20/05. The <br />sampling program will resume the approved sampling schedule in 2006. The 2005 sampling event maintained within <br />historical water quality values for most constituents. Chloride and total dissolved solids showed elevated concentrations in <br />2005, it is assumed that this increase is due to well repairs. <br />49 <br />