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<br />• <br />`I <br />Mountain Coal Company-West Elk Mine <br />Sylvester Gulch Road Geotechnical Investigation <br />36+00 <br />Seismic refraction resuhs reveal a second layer of higher velocity material which is shallow (~10 tt) on <br />the southwest slope and deeper (2213) on the northeast slope (Figure 17). The velocity of the first layer <br />is typical of unconsolidated sedimer~. Velocities for the second layer indipte sound bedrock. Velocity <br />results from the seismic refraction for the second layer are close to known velocities for some compete <br />sandstones. <br />Syvester Gukh seismic une 36+00 <br />7 <br />72 <br />0 <br />7290 .__ ._._ _. _._... _. _......... ____._.. . .. .. _. _..___.~NE.. <br />~ <br /> ~ <br />7250 . _~.. ... _._ ........ .... ... .. .. .. .. .. .. ..._~_.... ..__.. .. <br />7200 ~ . ~ <br /> <br />~~ ~ ~ <br />... .._ - 9i. __._ __...___ ... _,. _ .. _. _....._ <br />y__ __ .. ... <br /> Y <br />E pe ~ ytl <br />7220 .. .. Eo . . _ _ . ... _ _ .. .... . . . .. ... . _ . <br />~ ~ ~ an <br />7270 ._ .. ..__.9t1__ ._._~.. <br />.__.._._._ _.. .. .. _..... <br />720D .7 <br />_. .. .. c t7_ _.. V1_=~.35O R/S .. .. ... <br />_ .. .... <br /> <br />V2 = 7025 fl/s <br />--~Qqund 9idace <br />7790 ..... __ ____ _ ..._ _ _ <br />~BOUndaryl - - __ ... <br />neo <br />0 70 20 3o m so w 7o m eo 70D no ta7 730 if0 760 Teo 770 Teo 79o Zoo no za7 z+ o <br /> DENanoe (rq <br />Figure 17. Seismic refraction profile at 36+00. <br />37+00 <br />Seismic refraction results reveal a second layer of higher velocity material approximately 20 feet deep on <br />the southwest slope and 31 feet deep on the northeast slope (Figure 18). The velocity of the first layer is <br />typical of unconsolidated sediments. Velocities for the second layer indicate bedrock Velocity results <br />from the seismic refraction for the second layer are close to known velocities for some competent <br />sandstones. <br />.~ Slyve7cter 6~ Seisnie lJ~ 37a0a <br />7270 '~ ~ .. NE <br />~ ~. <br /> ~ <br /> <br /> <br />7zso m ~ <br />~. .. _ _ .. _ .. <br />o~ <br /> <br />~72a0 ~ ~ <br />.. ..a ..."_ _~ - __... _.. <br /> <br />7230 ~° 9s <br />_ yo . __ . .... _. - __ - _ <br /> pn Y ~ <br />7bD ... _ OQ _ _ ....._p..~. _ <br />V7 _ 1700 IYg <br />721D .. .. .... __. _ ... _. _ . _ _ _ _ ..... _ _ .... <br /> <br /> +~oune Sudace <br />7}90 ~BOUndaryl .... _... .. ... <br />7180 <br /> <br />-20 -10 O 70 m 3D 4D SD W 7D !tl ~ 700 770 11D 730 t/D }70 76D 1711 78D t90 37D 2}0 220 <br />OMenp Iftl <br />Seismic Refraction Surrey <br />Summary of Operations <br />Frgure 18. Seismic refraction profile at 37+00. <br />UMS, Inc. <br />Page 13 <br />05/17/03 <br />