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OxBow Coal Mine <br />Geotechnical Investigation <br />Seismic Retraction Survey <br />Summary of Operations <br />FIELD OPERATIONS <br />• Two seismic refraction surveys were conducted near OxBow Coal Mine as part of a slope stability <br />analysis April 9"' and 10ih 2003. <br />Survey 1 <br />A seismic refraction survey consisting of five spreads was conducted above the railroad April 9'~' <br />2003. A 120' spread ran parallel to the tracks across a gulley bearing N60E. An additional four <br />spreads, 240' each, extended up the gulley, bearing N I OE. <br />Survey 2 <br />On April 10"' 2(x)3 a second seismic refraction survey was conducted two gullies to the east. <br />Seismic data was gathered along a 240' spread, bearing N I SW, extending up a ridge just east of <br />the gulley of interest. <br /> <br /> <br />The surveys were located in the field using a handheld GPS and altimeter. Figure 5 is an Elk Creek <br />topography map with the approximate survey and landslide locations overlain on the map. <br />Fig. S. Survey 1, performed on 4-09-03, in red; Survey 2, preformed on 4-10-03, in green. Landslide <br />characterized in blue. <br />A 24-channel portable seismograph with 14 hertz geophones was used to log seismic data. Each seismic <br />spread contained 24 geophones set in the ground at 10 foot spacing. For each spread, a seismic shot was <br />taken 5 feet before geophone 1, between geophones 6 and 7, in the middle of the spread (between <br />geophones 12 and 13), between geophones 18 and 19, and 5 feet off the spread from geophone 24 (Figure <br />6). <br />UMS, Inc. Page 3 (l7/Oy/03 <br />