Laserfiche WebLink
<br />I <br /> <br />Woodward-Clyde Consultants <br /> <br />,. r. ~+'\-( <br />, , , <br />~vl <br /> <br />. <br /> <br />of the Pierre shale generally weathers to a depth of 3 to 10 <br /> <br />feet below the ground surface or below the overlying sediments. <br /> <br />The weathered shale may be soft and easily erodible. <br /> <br />. <br /> <br />The overburden Tertiary and Quaternary soils were <br />deposited over the top of the Pierre Sha~y eastward flowing <br />braided streams and strong wind. The ~~erial consists of <br />lightly consolidated to unconsolida~~graVelS and silts <br />with layers of fine, wind blown sands and l~~ silts. <br />These sediments tend to be qUit~ ~rvious and th: loess and <br />less dense stream sediments c~~e)SUbject to considerable <br />consolidation under conditio~~ ~ing and wetting. They <br />are also highly erodible. ~ <br />3. Geologic Structure~ <br />Both field examinatro~/.i6?e1'iminarY mapping indicate <br />that the Pierre shale in ~e s~e area is structurally <br /> <br />. fa~or~ble. No _e~~~~~~~~_i,ng~_~~a~~ng o:_:X~~S_Si_~~__~___~._ <br /> <br />- - - - - - - - --'ol'ntTn~g- h'a-s-rtef.. rounc nor'11as tnere Been any other ev Idence <br />J <.. "'-/ /_t_ J <br />of adverse tect'onic ~ormation. The alluvial and wind <br />deposited~~~S~iallY structureless as would be <br />expe~~~tream and wind-laid deposits. <br />4. 0,the,r. Cons ide ra)t ions <br />T~~~y{d~nce that montmorillonite minerals are <br />present in~f1:rre shale formation and at some locations the <br /> <br />. <br /> <br />I <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />formation may contain weak layers. The shale and weathered <br /> <br />. <br /> <br />shale may also have swelling tendencies that could adversely <br /> <br />- 8 - <br /> <br />. <br /> <br />I!IDo <br />... <br />