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DE.r,, ~2' 961THU) 10:25 WRIGHT WATER TEL:303 480 1020 <br />_: <br />Memorandum to CDMG <br />December 12, 1996 <br />Page 3 <br />P, 004 <br />above the fracture zone and beneath any surface Fractures. Second, within this continuous <br />deformation zone, the stratigraphy consists of interbedded shales and sandstones. Even if the <br />fractures happen to align within the sandstone units, the fractures will most likely not <br />continue through the ductile shale layers. Thus, there would not be vertical connectivity of <br />the fractures. <br />Dr. Pcndkton agreed with WWE's conclusion regarding fractures in the overburden and <br />focused more on the fractures that may occur parallel to open rock faces in the steep valleys. <br />He noted that these fractures vnll probably not close again. W WE agrees with Dr_ Pendleton <br />that the possibility of rockfall exists and MCC will address their commitments to monitor and <br />provide signs in the public safety plan. <br />LANDSLIDES NEAR MOUTH OF BOX CANYON <br />Mr. Rold summarized his findings regazding the landslides above the highway near the <br />mouth of Box Canyon emphasizing that the landslides are consist of several shallow (less <br />than 30 feet thick) slides rather than two deep rotational slides. Messrs. Rold and Dunrud <br />noted that even using a very wnservative angle of draw the landslides aze outside the <br />influence of MCC's mining. <br />Dr. Pendleton agreed that the highway landslides wilt not be rejuvenated by longwall mining. <br />He did note that along the upper Lone Pine road, there is a visible compression ridge on the <br />raised section of the embankment. The rotational component of the landslide is quite <br />evident. <br />SURFACE CRACKS ABOVE PANEL 8 <br />WWE agrees with the conclusions reached by Dames and Moore and reiterated by Dr_ <br />Pendleton. Specifically, the azea has numerous historic landslides and that the cracks formed <br />on the roads are not the result of longwall mining but rather continued landslide activity. Dr. <br />Pendleton noted tensile cracks further south which did not have the downslope bulge <br />associated with the landslides. He stated that these cracks likely resulted from subsidence <br />rather than landslide activity. <br />Please note that this memorandum is a draft and will nor be ftnalized until CDMG's <br />comments have been incorporated We look forward to receiving your comment as soon as <br />possible <br />D:\831 A32\ I BOjmIcICDMG Meetin5 No W.GOe <br />