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<br />dry since 1990 while the 892 well series have been dry since their installation. The <br />stratigraphy into which these wells were completed is believed to have been intersected during <br />the construction of the Moffat sediment pond during the fall of 1989. Consequently, these <br />formations have been able to drain fairly freely. Due to the draining nature of the formations, <br />it is not anticipated that significant potentiometric surfaces will develop in the future. <br />During 1998, all of these wells marginally responded to the wet spring conditions. A <br />review of the data appears to confirm the continued integrity of the aquiclude between the <br />Wadge seam and Lower Wadge unit and the lack of pore water pressure development in the <br />lower unit. In June 1999, the casings of wells 892S and 892E degraded sufficiently to <br />preclude measurements below 7,165 feet. <br />Elevations of the static water level in the Moffat stability monitoring wells are shown <br />in Chart 38. The static ground water well elevations are provided in tabular format in Table <br />16. The Moffat stability monitoring wells were measured once in 2007. Monitoring wells <br />215W, 215L, 218W, 218L, M892S and M892L were plugged and abandoned in May of 2007. <br />The monitoring wells were removed from the monitoring program plugged and abandoned in <br />accordance with TR-47. MR-52 inserted Well Abandonment Reports in Appendix 4.6-L of <br />the permit and they are provided in Appendix A. <br />9.0 Moffat Stability Monuments <br />A system of three control points and six monuments were established in the final <br />Moffat pit area during the fourth quarter of 1997. The purpose of the monuments is to <br />monitor the hillslope for long-term stability. The three control points were placed to form a <br />large triangle. The reference control point was established along the top of the hillside in <br />undisturbed ground above the final Moffat pit. The two additional control points (back-sites) <br />were established in undisturbed ground northwest and south of the reference point. The back- <br />sites were established to verify the location of the reference point. The monuments were <br />installed in pairs with the first pair, SM-1 and SM-2, established in the lower third of the final <br />pit area. SM-1 was placed approximately 130 feet south of the final pit highwall. and SM-2 <br />was placed approximately 340 feet south of the final pit highwall. The second pair, SM-3 and <br />SM-4, were installed approximately mid-way along the pit. SM-3 was placed approximately <br />110 feet south of the highwall and SM-4 was placed approximately 325 feet south of the <br />highwall. The last pair, SM-5 and SM-6 was installed in the upper third of final pit area. SM- <br />5 was placed approximately 150 south of the highwall and SM-6 was placed approximately <br />350 feet south of the highwall. The monuments consist of 7' to 8' sections of 2-1/2" diameter <br />drill steel driven 5-1/2' to 6-1/2' into the pit backfill material. <br />The monuments are to be surveyed quarterly the first year and annually thereafter. In <br />2003, a level loop was surveyed providing elevation information. However, due to an <br />equipment malfunction, x and y coordinates were lost. The 2007 stability monument survey <br />was performed August 24, 2007. The coordinates of the initial monument survey and <br />subsequent surveys are provided in Table 17. <br />16 <br />