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Fall 2008 Subsidence and Geologic Field Observations <br />Box Canyon, Apache Rocks, and South of Divide Mining Areas <br />. photographic observation point (Map ?) was established to provide a baseline for Future reference <br />during construction of Monument Dam and the mining of Longwall Panel E9. From this <br />location, various features associated \vith a relatively large landslide south of the Minnesota <br />Reservoir can be readily identified including the head scarp, hummocky topography. and <br />numerous spring and %yctland areas indicating discharge locations for water stored within the <br />landslide mass. Figure 15 provides a good oyerviexy from this location relative to Minnesota <br />Reservoir (empty at the time or our field visit), Monument Dam, and the landslide area to the <br />south (distant side) of the rescr\ mil'. <br />LJ <br />F `? s ft r r. " `• <br />'ti : '. <br />Ilk% <br />Figure 35. Fall 2008 southeasterly view of the Minnesota Reservoir, Monument Dam, and <br />Dry Fork Minnesota Creek drainage as observed from the MCC landslide monitoring station. <br />0 <br />A telephoto view of the %lonument Dam area (Figure 36) reveals the modifications that have <br />been completed on the (]run and in the area south of the left abutment. Figure 37 shows the same <br />area as observed during our fall 2007 field visit. A comparison of 1:Igures 36 and 37 sho\\s that <br />the upstream side of Monument Dam has been armored with riprap. that the toe drain and <br />emergency spillway areas have been reworked, and the area south of the left abutment has been <br />excavated to relieve lateral pressure from the landslide. <br />831-032.790 Wright Water Engineers, Inc. Page 51 <br />December 2008