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<br />• <br /> <br />Mountain Coal Company -West EIk Mine <br />Sylvester Gulch Road Geotechnipl Investigation <br />Seismic Refraction Survey <br />Summary of Operations <br />Data from the borehole at 35+00 indicates a sandstone cobble layer at a depth of 24 ft (Fignre 1~. Below <br />the cobble layer borehole data indicates sandstone bedrock at a depth of 29 8. Apparent velocities from <br />the seismic refraction are too slow for expansive competent sandstone bedroclS however, as indicated by <br />the scatter of emergent rays in the seismic data, the profle is likely indicating that proceeding up dte steep <br />Banking slopes the bedrock horizons are varying from competent sandstone to weathered sandstone and <br />shale. <br />Frgure 16. Correlation between seismic refraction profile and borehole logging at Station 35+00. Green line <br />indicates surface. Red line indicates the acoustic impedance boundary. <br />35+00 <br />Brovn. propel and sad, IRtle a9mtcs, midst <br />z <br />4 <br />aromkvEmY ooas~ i~+tM daetie, nwieL a <br />wgnii-rich soi al GS feek. PAY o^9~ ~Psci <br />e <br />&ow6 m -- <br />cmle~ eroy a! 7D to 1Y fffit <br />~ ne n smkhved, nd modwkdy phalic ma6&, <br />rtiust <br />Q• <br />. V °'. <br />A <br />fo IZ 9®IdStale CObbilS 414 Q>~. medNll IOWP. Ot 21 - <br />U <br />W t~,r ro ~, . ~ prvire! <br />Note: tent xm~tme bclodc at 2i feet refund <br />Y. <br />75 104 <br />UMS, Inc. <br />Page 12 <br />05/17/03 <br />