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Memo to Boulay & Berry <br />Bear [Il Landslide <br />page 4 <br />July, 1997, in addition to my personal knowledge and experience in the immediate area, provides <br />me with an understanding of the mass wasting character of the immediate vicinity of the <br />landslide. The Bear III mine permit area has been characterized by frequent and extensive mass <br />wasting events since 1983. The Bear mine portals and portal fan were damaged by mudflow <br />events on several occasions. Rotational landslides have damaged the portal access road and <br />portal bench on several occasions. The valley slope above the landslide under consideration <br />evidences several large ancient scarps and an extensive mudflow complex. The WWE report <br />maps delineate numerous large, open scarps and tension fractures above the active landslide. <br />Several of these landforms have been active as recently as 1996. If precipitation was abnormally <br />high throughout 1997, as WWE postulates, it seems likely that other recently active landslides <br />and mudflows would have been reactivated. None of the neazby mass wasting sites exhibited <br />any activity during the summer or fall of 1997. <br />(3) Bruce Stover and I observed wet areas adjacent to and on the upper portions of the <br />landslide mass on February 10, 1998, as described above. The moist to saturated areas <br />described within the extensional trough at the head of the landslide were unfrozen, even <br />though the ambient air temperature was approximately 20° F at 8:30 am. The moist area <br />was devoid of snow, in contrast to 6 to 18 inches of snow retained on much of the <br />adjoining slope and landslide mass. Warm water vapor was issuing from the base of the <br />scarp, appazently from the C-Seam subcrop. This wet to saturated condition persisted <br />along about the eastern half of the scarp to just below where a lazge boulder had fallen <br />several days before the slide occurred. West of this point the main scarp trough was <br />frozen and snow covered. If WWE postulates that this moisture represents infiltrated <br />precipitation, why is it still appazent two months after the failure? Why has the ground <br />temperature remained sufficiently elevated to preclude ground frost? <br />Based upon these observations it appeazs more plausible that the waters which initiated <br />movement in the upper eastern portion of the landslide mass issued from the bedrock <br />strata beneath the colluvium comprising the failed landslide mass. In addition, the fact <br />that the moist and saturated areas within the extensional trough and adjacent to the <br />reclaimed Bear II mine western-most portal were not previously observed by WWE <br />suggests that warm groundwaters have continued to enter the landslide mass, eventually <br />wetting enough of the overlying and adjacent soil materials to result in the formation of <br />the warm, saturated areas we observed on February 10, 1998. <br />Geomorphology of the Hillslope <br />The modem landslide under consideration occupies a landscape with numerous mass-wasting <br />artifacts. The subject landslide occupies the toe of the north facing valley sideslope of the valley <br />