2008-04-30_REPORT - M1973021 (3)

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Observations of the stabilized slope area indicate no visible movement or large erosional features. Aggregate Industries provides survey support to monitor movement of this slope as well. However, survey data is collected as conditions change and no survey was completed in 2007. 3.2 North Quarry Geotechnical data was collected for the areas mined in 2007. These areas include one highwall face mined to base elevations of approximately 6220 feet above MSL as shown on Figure 2. The highwall face is referred to as Bench D for reference in this report. This bench represents an increased depth of mining in the North Quarry from last year and includes expanded mining z areas to the south (north facing) and east (west facing) . The type of rock encountered in the highwalls is consistent with rock types described in previous geotechnical addenda and primarily consists of fine to medium grained granitic gneiss or biotite gneiss. Occasional pegmatitic intrusions or biotite schist zones are also present in the area. Gneiss observed in the Bench D highwall is slightly to moderately weathered and generally displays two prominent joint sets and a foliation surface. Joint spacing ranges from approximately 4 inches up to 10 feet. Joint surfaces generally are slightly rough to rough and are usually closed. When joint surfaces are open or exposed, the joint faces are typically slightly to moderately weathered with iron staining. The joints generally do not contain infill material. Foliation plane spacing ranges from less than one inch up to 4 feet. Foliation surfaces generally are smooth to rough and are usually closed. When foliation surfaces are open or exposed, the aperture is up to one inch and the foliation faces are typically slightly weathered with iron staining. The foliation generally does not contain any infill material. The highwalls observed were dry and seepage through the rock is not anticipated. Average RMR values calculated for the rock exposed in the highwall of Bench D range from 58 to 69 indicating fair to good rock. Joint orientation field data and RMR spreadsheets for the highwalls are included in Appendix A. The Bench D scanline was approximately 560 feet long and was separated into 6 discrete sections. Stations 0+00 through 0+75 consisted of massive granitic gneiss. The foliation strike varies in this area due to minor folding of the gneiss and ranges from 92 to 102 degrees. Foliation dips were 12 to 22 degrees, parallel or into the highwall, with average spacing of approximately 12 inches and foliation apertures were closed and rough. The primary joint set strike ranges from 210 to 230 degrees and generally dips from 75 to 85 degrees. A secondary joint set is evident in this area and exhibits a strike of 310 to 320 degrees with dips of 80 to 90 degrees. The spacing of joint set one averaged approximately 21 inches and the spacing of joint set two averaged approximately 48 inches. Joint apertures were moderately open to closed with slightly rough faces. z Per conversations with the current Aggregate Industries Morrison Quarry Plant Manager. -3- F:\3919 038Wnnual_Rcport_2007\Gcotcch_Addcndum_2007Wnnual_Rcport_2007_Geotcch.doc Apri12008