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4.0 ENGINEERING GEOLOGY <br />The following discussion of engineering geology is based on • <br />data gathered in the field and on photogeologic interpretation. <br />The main emphasis in this discussion is on the effect that geology <br />will have on the haul roads and on the sedimentation pond. <br />Technical geological terminology is used only for clarity or <br />precise meaning in the following descriptions. <br />The abbreviation "sta." is omitted in describing uniform <br />reaches and making other references to survey stations. <br />4.1 Haul Road A <br />This haul road extends from the origin (0+00) to 161+03.17. <br />The entire length of this alignment is within the Lewis Shale <br />outcrop and Alluvium associated with it. Much of the alignment • <br />crosses colluvial slopes developed in weathered Lewis Shale. <br />Although no fresh exposures of shale were observed within the 200- <br />foot corridor in which the alignment is centered, construction <br />excavation may encounter bedrock locally. In the eastern half of <br />sec. 32 and in the northeastern part of sec. 5 the alignment <br />crosses Alluvium of Scotchmans Gulch. <br />The effect of rock structure where cuts are made in the Lewis <br />Shale or in its weathered equivalent should be minimal since <br />unweathered bedrock will not be found in extensive reaches. The <br />dip of the shale and sandstone beds, if encountered in cuts <br />generally will be less than 10°. <br />Cuts, according to the cross sections, are established on <br />slopes of 1.5:1 to 3:1. If necessary or desirable these cuts could • <br />be steepened to 1:1, although this is steeper than regulations <br />18 <br />