2008-04-30_REPORT - M1973021 (3)

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L~ ~ ' .~ TETRA TE~~1 • • 2002 GEOTECHNICAL ADDENDUM • The 2002 geotechnical addendum indicated mining in the North Quarry was completed on the north and east sections of benches to approximately elevation 6,545. The mine slopes were recorded as 50 feet highwalls with 40 to 60 feet benches. The rock described in the report was granitic gneiss with mafic and felsic intrusions (felsic dikes and pegmatites). Joints in the rock mass were described as closed with slightly weathered surfaces and spacing of approximately '/z to 2 feet. Foliation orientations vary greatly due to the folding of the rock with an average dip to the west. The rock mass was defined as primarily competent with the following exceptions defined as poor: • An anticline/syncline pair dipping out of the mined rock face • A vertical dike, bearing northwest • A vertical dike and shear zone, 25 feet wide, bearing 250 degrees • An anticline dipping out of the rock slope • A fracture, 40 feet long, striking east-northeast 2003 GEOTECHNICAL ADDENDUM The 2003 geotechnical addendum indicated mining in the North Quarry was completed on north benches to approximately elevation 6,460. The mine slopes were recorded as 50 feet highwalls with 40 to 60 feet benches. The rock described in the report was granitic gneiss with mafic and felsic intrusions (felsic dikes and pegmatites). Joints in the rock mass were described as closed with slight to moderately weathered surfaces and spacing of approximately '/2 to 2 feet. Foliation orientations vary greatly due to the folding of the rock with an average dip to the west. The rock mass was defined as primarily competent with the following exceptions defined as poor: • A vertical dike, 8-10 feet wide, bearing northwest • A fracture/shear zone, 170 feet long, cross cutting highwall • A shear zone striking at approximately 180 degrees • An anticline/syncline pair dipping out of the slope 2004 GEOTECHNICAL ADDENDUM The 2004 geotechnical addendum indicated mining in the North Quarry was completed on north, east, and west benches to approximately elevation 6,400. The mine slopes were recorded as 40 feet highwalls with 50 to 60 feet benches. The rock described in the report was granitic gneiss with mafic and felsic intrusions (felsic dikes and pegmatites). Joints in the rock mass were described as closed with slight to moderately weathered surfaces and spacing of approximately Yz to 2 feet. Foliation orientations vary greatly due to the -3-