2012-01-27_REPORT - M1973021 - Laserfiche WebLink

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Bench 7250 • Stations 2 +90 through 3 +46 consisted of moderately fractured biotitic gneiss on the lower 10 feet (station 2 +90) to 0 feet (station 3 +10). The remaining portions of the highwall (up to 100 feet) are moderately fractured granitic gneiss. Between stations 3 +10 and 3 +46 the rock above 50 feet is native surficial rock present pre- mining. The foliation strike in this area varies due to minor folding averages 320 degrees with an average dip of 20 degrees southwest. Foliation spacing ranges approximately 4 inches to more than 2 feet for the biotitic gneiss and 2 to 7 feet for the granitic gneiss, and foliation apertures were tight and slightly rough to very rough. The primary joint set strike averages 310 degrees and generally dips from 80 to 90 degrees southwest. A second primary joint set strike averages 45 degrees and generally dips 80 to 90 degrees northwest. The spacing of the primary joint sets varied widely, but averaged approximately 18 inches. Joint apertures were tight to moderately open with slightly rough to rough faces. • Two secondary joint sets are present in this section of the highwall. The joint sets have average strikes of 165 and 60 with average dips of 45 degrees northeast and 40 degrees northwest, respectively. The spacing of the secondary joint sets ranged from approximately 1 to 7 feet. Joint apertures were tight to moderately open with slightly rough to rough faces. Due to the maximum height of the highwall on bench 7350, special care should be taken to avoid raveling from high on the highwall that could potentially extend 25 feet or more from the highwall toe. A berm at the base of the highwall will tend to restrict the range of the raveling rock. Figure 5 is a photo documentary of the features observed in Bench 7350. The Bench 7250 scanline is approximately 305 feet long and was separated into 4 discrete sections. The approximate orientation of the highwall varies between is 30 degrees (north 30 degrees east) and 325 degrees (north 35 degrees west). • Stations 0 +00 through 0 +90 were unmappable due to overburden and rock cover. The condition of the highwall is unknown in this section. • Stations 0 +90 through 1 +10 consisted of moderately fractured biotitic gneiss. The foliation strike varies in this area due to minor folding and ranges from 265 to 270 degrees. Foliation dips range from 29 to 30 degrees southeast to south. Foliation spacing ranges approximately 4 inches to more than 2 feet, and foliation apertures were tight and slightly rough to very rough. The primary joint set strike ranges from 145 to 170 degrees and generally dips from 62 to 80 degrees northeast. A second primary joint set is evident in this area and exhibits a strike of 210 to 225 degrees with dips of 78 to 90 degrees southeast. The spacing of the primary joint sets varied widely, but averaged approximately 18 inches. Joint apertures were tight to moderately open with slightly rough to rough faces. - 6 - Morrison Quarry Annual Report 2011 P \23514\ 133 - 23514 -1 2002 \Deliverables\Deliv -01- Annual Report \Annual Report_2011_Geotech doc January 2012