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Memo to Boulay & Berry <br />Bear III Landslide <br />page 3 <br />(4) There are 3 possible sources of water to the slide: surface precipitation, groundwater flow <br />from the B- or C-seam workings, or groundwater flow independent of the coal seam / <br />mine workings. <br />1 do not agree with WWE's hypothesis that the water source which triggered the landslide was <br />surface precipitation. WWE postulates the precipitation source based on several points: <br />(1) The was an "abnormally wet spring, summer, and early fall". <br />(2) There were cracks above the area which could have allowed precipitation to infiltrate into <br />the colluvial tnaterials. <br />(3) There was no observed evidence of "seeps, springs, or wet areas" on the slide mass or at <br />the toe, therefore they conclude that the water source could no[ be groundwater. <br />My discordance with WWE's hypothesis stems from the following: <br />(1) No data is. presented within the report to demonstrate that precipitation at this site actually <br />was abnormal during 1997. Bruce Stover spent virtually all of October and half of <br />November conducting Yield work in Cedazedge, down valley from the Somerset area. <br />Bruce reports that the fall weather was predominantly dry and clear. He can only recall <br />one snow storm /wet period during his field stay, and would not characterize the fall <br />weather in his field area as unusually wet. <br />Late fall is extremely inconsistent with natural precipitation-induced mass wasting events <br />in semi-arid western Colorado. The vast majority of such landslide events occur during <br />the spring and early summer, following snow melt and spring precipitation. Landslides <br />are uncommon in November, even in the North Fork valley. Fall /early winter is <br />normally the driest time of the year, both in terms of precipitation and groundwater <br />levels. Streams run at basetlow levels. If the anomalous moisture levels postulated by <br />WWE occurred, i[ should be reflected by precipitation data within [he permit area and <br />stream gaging data for the immediate area. Such data would help support this portion of <br />WWE's theory. <br />(2) I could discern no evidence of infiltration of precipitation through the slide mass. WWE <br />states that the slide mass was "unusually dry", yet calls upon abnormally high <br />precipitation as the source of waterfor induction of failure. <br />Examination of stereographic aerial photographic coverage from the years 1980 through <br />