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Exhibit 60C <br />Subsidence Evaluation and 2004 Geologic Hazard Field Observations <br />West Flatiron Lease Area <br />I• <br /> <br /> <br />e 5 <br />r~ <br />~ ~ <br />Q <br />~ 3 <br />~ 2 <br />1 <br />® ~ <br />~ ~ -fl <br />~ ~ <br />_. ~ -2 <br />r~ <br />~ -3 <br />~ _~ <br />~ -5 <br />~~m <br />O <br />~ O <br />/ ~ <br />0 <br />o `~ -]E <br />' m <br />0 <br />0 <br />0 0.2 0.4 0.6 0.~ fl.O fl.2 fl.4 fl.6 <br />~~~1 <br />Figure 1. Graph showing maximum tilt (Mm) and horizontal strain (Em) versus the mining panel width to <br />depth ratio (W/d). Tilt (circles) and horizontal strain (squares) for the West Elk Mine subsidence <br />monitoring network are shown with the average National Coal Board (1975) longwall curves. <br />831-032.650 <br />November 2004 <br />Wright Water Engineers, Inc. <br />Page 12 <br />