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' Memorandum to Christine Johnston <br />October 7, 1999 <br />' Page 13 <br />' • Extensive landslides occur in siltstones <br />below the Ohio Creek sandstones on the <br />west side of Box Canyon near the <br />headwall (Figure 9). <br />Location 15. Located on the second narrows <br />south of Location 14 above the southeastern <br />part of projected longwall Panel 20. <br />' • Overburden depth to [he B-Seam is <br />approximately 2,200 ft. <br />y.~-~.'• ~ - 'l ~~ <br />;~r`- <br />~" <br />Figure 9. Premining landslide (slump) occurring in <br />siltstones of the Ohio Creek Member on [he west side of <br />Box Canyon near the headwall. <br />• Cracks, a few inches to perhaps as much as '/Z <br />ft wide and trending generally pazallel to ridge, <br />occur along [he cliff edge. Unstable rocks are <br />locally present at cliff, which may fall any time <br />under natural processes. <br />• Large, unstable boulders are located <br />downslope from cliff edge on the east side. <br />• A rockfall is located S50°E of point across a <br />canyon that divides West Flatiron near the top <br />of the Ohio Creek Member (Figure ] 0). <br />Location 16. Located above the south-central part of projected longwall Panel 24 neaz base of <br />landslide that occurs upslope from drill road to West Flatiron. <br />• Overburden depth to B-Seam is estimated to be 2,000 ft. <br />• Construction of extensive tank traps appeazs to have mostly caused the slide. No slide <br />was present in the late 1970s, when [used this road during mapping for the USGS. <br />Location 17. Located at monitoring well 96-27-1 above the western part of the projected gate <br />roads between longwall Panels 14 and 15. <br />• Overburden depth to B-Seam is about 1,600 ft. <br />• Ron measured a water level depth of 1,234 ft on 7-23-99. <br />Wright Water Engineers, Inc., 2490 W. 26'" Avenue, Ste. 100A, Dem.2r, CO 80211 <br />Tel. 303/480.1700; Fax. 303/480.1020, e-mail:krwrigM@wrightwa[er.com <br />