Laserfiche WebLink
1100318 R0T0 0811 JRW1 13 <br />the community is supportive of the long-term visual enhancement of the layback <br />project, there is also a concern to not disturb more land than is necessary for the <br />project. When measurement of the joint sets in the granite revealed a steeply <br />dipping bedding plane to the east, the design of the planned cliffs was modified to <br />60 degrees from the horizontal. The overall geometry of the project site no <br />longer allowed the 2:1 slopes as originally desired, unless significantly more <br />land and more planned cliffs were incorporated. This increased disturbance and <br />cliff requirement may have conflicted with previous expectations of the amount of <br />new land to be disturbed, but not significantly. <br />The proposed design allows stable, natural-appearing cliffs, whose height is both <br />safe to work under and can be hidden as the trees reach maturity in the long- <br />term. The 1.5:1 slopes will be stable, due to the underlying benches of granite, <br />and will support vegetation. Other reclaimed areas of the quarry have similar <br />1.5: 1 slopes, and have successfully maintained grass growth for periods of five <br />to fifteen years.”29 <br />Figure 15 shows the details of the slope construction. The method of construction is described <br />in the amendment as follows: <br />“The sloped high-walls, which will be designated as "cliffs" hereafter, will be <br />constructed by pre-split drilling and blasting the granite in the ridges at the <br />western edge of the mining area. The slope of the cliffs will be 60 degrees from <br />the horizontal, as recommended in the rock mechanics report. The cliffs will be <br />pre-split for each 30 foot (vertical) bench, with a small horizontal offset <br />(approximately 1-5 feet) between cliff faces. The production drill holes for the <br />subsequent bench below the cliffs toe will be terminated prior to penetrating the <br />60 degree projection line (indicated in Exhibit C-4 [Figure 15]), so that the back <br />break will not undercut the toe of the cliff. Prior to the excavation of the next <br />lower bench, the slope will be roughly graded to a 1.5H:1V slope with granite <br /> <br />29 Permit Application Amendment, Pikeview Quarry, Permit Number M-77-211, Received by Colorado Division <br />of Minerals and Geology on September 22, 2000, page 14 (Appendix 14)