Laserfiche WebLink
Stations 1+65 to 2+50 consisted of weathered granitic and biotite gneiss with very <br />close joint spacing. Foliation and joint orientations were indistinct due to the very close <br />spacing of joints combined with the amount of slough material covering the highwall. <br />Joint spacing appeared to be less than 1 inch up to approximately 3 inches. The rock <br />displays moderate iron staining and is assumed to be disintegrated under the sloughed <br />material due to weathering. The majority of the sloughed material is present due to <br />recent blasting for bench development. Blocks observed in this area were generally less <br />than 6 inches diameter due to the disintegrated nature of the rock. Raveling from this <br />zone is anticipated to cause only local operational delays. <br />Stations 2+50 to 5+00 consisted of granitic gneiss. This part of the highwall was <br />undergoing active mining and was, therefore, not involved in the scanline but was <br />observed from a distance. From approximately station 2+50 to 4+00, the highwall was <br />buried in the rubble from a recent blast. From approximately station 4+00 to 5+00 the <br />highwall was exposed, consisting of fresh to slightly weathered granitic gneiss with <br />approximately the same joint orientation and spacing as stations 2+20 to 4+00 of <br />Bench 6880. The rock also contained 3 dark colored, near vertical dike intrusions <br />which are similar to the ones present in the west wall of the Central Quarry. The rock <br />for this section of the highwall is assumed to be very good due to the slight weathering <br />and the wide joint spacing. <br />MW Figures 6 and 7 are a photo documentary of the features observed in Bench 6820. The <br />AdIlk weathered material in the east-west part of the highwall will be removed before this bench <br />reaches its final configuration. <br />AM& Bench 6760 was observed but no scanline data was collected. This bench is under initial <br />development and still consisted entirely of rubble from development blasting. It is assumed <br />that the highwall orientation and rock type will be similar to the benches above. <br />4.0 RESULTS AND DISCUSSION <br />Observations of the North Quarry indicate little change in the finished slopes. Local rock <br />sloughing was observed and classified as minor based on rock accumulations observed on <br />bench surfaces throughout the North Quarry. Reclamation work will continue in 2009 on the <br />upper west slopes of the North Quarry and the majority of material sloughing onto the benches <br />is anticipated to be related to this activity. The condition of the remaining North Quarry is <br />anticipated to remain stable with only small scale rockfall expected to occur. <br />Observations of the Central Quarry indicate little change in the finished slopes. Local rock <br />sloughing was observed and was classified as minor based on rock accumulations observed on <br />bench surfaces throughout the Central Quarry. The general condition of the highwalls is <br />anticipated to remain stable with only small scale rockfall expected to occur. <br />The baseline rock conditions described in Amendment 3 to Mining Permit M-1973-021 are <br />"competent" for granite or biotite gneiss and "poor" for shear zones or highly to extremely <br />weathered zones that have the potential to decrease the stability of the slope. The conditions <br />observed in highwalls mined in 2008 in the South Quarry indicate that the rock is <br />-6- <br />Morrison Quarry Annual Report 2008 February 2009 <br />F A3919_03 8\Annual_Report_2008\Geotech_Report_2008\Annual_Report_2008_Geotech.doc