Laserfiche WebLink
<br />Memo to Dave Berry <br />Bowie No. 2 Additional Geotech Study <br />page 4 <br /> <br />analysis". With its original report, Maxim Technologies referenced a <br />major, recent rock slope failure which occurred just to the east of the <br />proposed portal area. At other locations in the report the entire bedrock <br />section is referred to as meta-stable. The slide in question occurred in <br />the early 1980's in response to the bulldozing of several light access <br />prospect drilling roads by Coors Energy while exploring the property. The <br />effected bedrock section is clinkered by subcrop coal burn, resulting in <br />typical deflation fracturing of the overlying bedrock. The Bowie No. 2 <br />permit application contains references to a general outcrop burn zone <br />throughout the property anticipated to be up to 300 feet in width. <br />On August 28, 1996, Jim Stover and William Bear, Jr., conducted Dave <br />Berry, Bill Carter and me on a tour of the permit area. We visited the site <br />of the landslide discussed above. We also observed several smaller but <br />apparently geologically analogous landslides in other portions of the <br />permit area. These landslides each appear to have initiated as a bedrock <br />failure in the steep exposed upper bedrock slopes of the site. This <br />bedrock appears to have been weakened by relaxation along joints and <br />bedding planes. The reddish oxidation of the sandstones and claystones <br />suggests the effects of outcrop combustion of the coal seams within the <br />bedrock section. Following combustion the seams decrease in volume, <br />subsiding the overlying bedrock, resulting in fracturing and joint <br />separation. In the case of the referenced landslide, Coors Energy <br />excavated small roads for exploratory drilling in the early 1980's which <br />precipitated an almost immediate bedrock failure. In addition, however, a <br />large soil failure was subsequently initiated immediately downslope from <br />the runout debris pile of the bedrock failure. I suspect that the failure of <br />the bedrock face loaded the adjacent ancient landslide debris, resulting in <br />amore viscous, flow-like landslide. In fact several lobate generations of <br />failure, progressing downslope, appeared evident during our short and <br />cursory examination on August 28th. <br />I suspect that the anticipated storage bench and portal bench cuts of up to <br />80 feet in height could experience significant destabilization problems, <br />