Laserfiche WebLink
• 19+00 the alignment is within the outcrop area of the Lewis Shale. <br />From 19+00 to about 57+00 the alignment is on colluvium developed <br />adjacent to the Alluvium along the west side of the main drainage. <br />From 19+00 throughout the balance of the alignment, alluvial and <br />colluvial deposits will contain more sand than shale because of <br />traversing through areas weathered from the Williams Fork Formation <br />which has a higher content of sandstone than the Lewis Shale to the <br />north. <br />At various points on or near the alignment in the reach from <br />62+00 to the terminus, outcrops of sandstone in the Williams Fork <br />Formation were observed and dips were measured as feasible. Much <br />of the alignment from 62+00 to the terminus will pass through <br />vegetated colluvial cover. This cover should be relatively thin <br />• where cuts are to be made. <br /> The overall rock structure, particularly in the sandstone, is <br />favorable to the planned cuts, although joints which were not <br />measured could cause some rock movement into cuts. Rock cut slopes <br />can stand more steeply than shown in the cross sections. Generally <br />the rock cuts could stand at 1:1 or possibly 0.75:1, depending on <br />local fractures. <br />The most critical aspect in design and construction of this <br />alignment is to provide adequate surface drainage to remove water <br />from cuts (and fills) as quickly as possible and with minimal <br />erosion. <br />The following uniform reaches were scaled from a 1"=400' <br />profile of the alignment. Cross sections at specific stations <br />• along the alignment were also available and were reviewed with <br />respect to geology. <br />23 <br />