2012-01-27_REPORT - M1973021 - Laserfiche WebLink

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2.0 2011 MINING SUMMARY 2.1 North Quarry Mining in the North Quarry was completed as of December, 2007. The North Quarry is currently being used as a raw water reservoir by the Town of Morrison and Aggregate Industries. As such, there was no major rock disturbance, mining, or reclamation activity in the North Quarry in 2011. Figure 2 shows the current configuration of the North Quarry, including the reservoir, north fill slope, and north repository. 2.2 Central Quarry Mining in the Central Quarry was completed as of December, 2001. As such, no major rock disturbance or mining occurred in the Central Quarry in 2011. Backfilling with stripped material from the South Quarry continued in 2011 as shown in Figure 3. 2.3 South Quarry Mining in the South Quarry continued in 2011, expanding the pit primarily to the west with minor pit expansions to the north and south. Material was mined from approximate elevations 7500 to 6700 feet. Benches mined in 2011 have temporary slope configurations consisting of 60 to 100 -foot highwalls and 30 to greater than 150 -foot benches. One expanded highwall and two new highwall and bench areas were developed in 2011. The total highwall height increased from 480 feet in December, 2010 to 800 feet in December, 2011. The approximate area mined and or disturbed in the South Quarry in 2011 is shown on Figure 4. Figures 5 through 8 are photo documentaries of the highwalls surveyed for this report. In addition, the haul road on the west part of the active mine was extended to access future mining areas. 3.0 FIELD DATA At locations exposed by mining in 2011, rock mass data including joint orientation and dip, foliation orientation and dip, rock mass rating (RMR) classification estimates, and unusual rock features such as shear zones, persistent intrusions, or weak rock zones, were documented. Orientations were collected using a Brunton compass (10 degree east magnetic declination) and recorded using the right hand rule. All orientation measurements were estimated from a safe distance back from the highwalls due to active mining activity, rockfall safety concerns and as requested by Aggregate Industries (AI). An exploratory borehole was advanced from bench 7350 to a depth of 690 feet below the surface (elevation 6660). The borehole was advanced using HQ (4.8 cm) coring methods to obtain subsurface data to assist in mine highwall design. Select samples obtained from the drilling were submitted for laboratory analyses. The testing included moisture, density, unconfined compressive strength with Young's Modulus, direct shear on joint (at confining pressures of 300, 600, 900 psi), direct shear on saw cut (at confining pressures of 300, 600, 900 psi), and slake durability. - 2 - Morrison Quarry Annual Report 2011 P \235I4 \133- 23514- 12002\ Deliverables\Deliv -01- Annual Report \Annual_Report_20I 1_Geotech doc January 2012