Laserfiche WebLink
tilit" <br /> rt- - . � slip surface along upturned foliation <br /> qy Y <br /> �'. "N '• i V� 4 Plane <br /> `4 \., .f -.- ,g K <br /> -..r ,fir. �'°_ `-, <br /> —S • "' <br /> ,. '° - "- banded gneiss with normal, <br /> —.+J .:•••"*.,3- .. •asterly dip into highwall <br /> A e - .- r r <br /> ' .p,,,r.. ',...„c".40,a` '„r'=ti w'-'42 t ''{-:t h‘,...-*:.;-...-.4 , S <br /> FIGURE 2.Pit highwall on april 28,2019,viewed to the south-southeast. The foliation in the banded gneisses is steepened along a <br /> southeast-northwest axis,creating a localized area where the foliation planes become possible slippage plains. <br /> Figure 2—Pit Highwall with Localized Banding <br /> 1_2 Highwall Dimensions <br /> The current highwall at the Shaffers Crossing quarry is 95 feet tall at the highest point and <br /> roughly 750 feet long. Aerial surveying of the site topography took place in July 2018 and can be <br /> seen on the Falcon Surveying, Inc. map titled Topographic Survey. This is attached. Based on <br /> this survey and the accompanying aerial imagery, it is clear that the edge of disturbance along <br /> the top of the highwall is close to the permit boundary, but still within the permit boundary. <br /> 2. Current Highwall Stability Evaluation <br /> According to the 2004 Brierley report,the geologic layout of the deposit being mined consists <br /> mostly of structures (i.e. foliation planes) dipping into the active mining highwall. The updated <br /> description of the current highwall found in Section 1 shows that the rock types and structures <br /> have not varied from the original Brierley analysis in any meaningful way. Structures continue to <br /> dip into the highwall with slight shifting of the strike from parallel to the highwall face to <br /> slightly more easterly. Since the geologic conditions of the highwall have not changed,the <br /> current slope stability will be evaluated in context of Brierley's stability determinations. <br /> Brierley determined that the geologic conditions would produce a stable slope at 1:3 (1:1.29) or <br /> shallower. An evaluation of the highwall slope found four locations of fairly steep slope to <br /> measure and compare to the required limit. These locations can be found in Figure 3 below. The <br /> steepest of the measured slopes is 1H:2.7V. This is still less than the maximum slope of 1H:3V <br /> identified by Brierley as the limit for stability. <br /> Shaffers Crossing TR 4 <br /> X (.reg I.cw icki and:%ssocintn,PI.1.C' <br />