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Geotechnieal Evaluation of Mine-Induced Seismicity on Monument Dam <br />Doreey $ Whitney, LLP <br /> <br />The left and right sides of the valley (looking downstream) near the dam and reservoir <br />contain numerous active and past landslides. The right embankment abutment azea appeazs <br />to contain evidence of a previous landslide but does not show any obvious signs of recent <br />movement. The left abutment area contains signs of more recent landslide activity including <br />fresh scarps, surface cracks, and intermittent seeps emerging from the slope surface. <br />Previous geologic mapping of the project site (Van Slyke, 1987) shows two distinct, adjacent <br />landslide lobes on the left side of the dam and reservoir, one forming the left abutment of the <br />dam and the other located upstream of the dam above the reservoir rim (refer to Figure 2.3). <br />The landslide at the left abutment is approximately 500 feet wide and has a slope length of at <br />least 800 feet that extends from the downstream earthfill dam toe to a visible scarp located on <br />the slope above the left abutment. The landslide located upstream of the dam is <br />approximately 800 feet wide with an exposed slope length of approximately 500 feet that <br />extends from the reservoir rim to another visible scarp located above the south side of the <br />reservoir. <br />r1 <br />• <br />G EI C! 1 1 060350 D6AI~IbMOnwnmt Dem GmtmMiN Evil <br />March 2006 <br />