1995-03-17_GENERAL DOCUMENTS - M1973021

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T Cooley Gravel Company 17 March 1995 Page 3 of 9 Morrison Quarry - 1994 Annual Report Rock encountered in the borings was primarily a granite gneiss rich in feldspar, quartz and pink garnet, with muscovite and biotite micas in variable amounts, and with other secondary minerals. A total of 347.0 linear feet (LF) of borehole was drilled of which 321.0 LF was diamond cored with NX wireline double tube core barrels and 26.0 LF was reamed with a tricone bit to establish starter holes for the core barrel. Of the 347.0 LF of borehole, approximately 78 percent of the rock encountered was granite gneiss with minor migmatitic granite porphyry in veins and pods; approximately 14 percent was more mafic diorite gneiss; approximately 5 percent was potassium feldspar-rich layers of pinkish to salmon- colored granite porphyry; and approximately 3 percent consisted of mafic hornfels with a similar composition to the diorite gneiss, but without the directional structure of the gneiss. Occasional, minor seams and layers of schistose gneiss were also encountered within the granite gneiss and diorite gneiss where micaceous minerals have been concentrated by regional and localized folding and faulting. The rock core obtained from the core borings is generally hard to very hard, fresh to slightly weathered and very closely to moderately closely jointed and fractured. Three primary joint sets exist: One set is controlled by the gneissic foliation and dips from shallow to moderate angles of approximately 10 to 40 degrees from horizontal;two sets are vertical to steeply dipping and occur nearly orthogonal to each other and to the foliation joint set. The joints vary from rough, planar and tight to rough, stepped and open. Open joint surfaces vary from clean to coated with either weathering oxides or clay. Tight joints include calcite and quartz healed joints. Other minor features observed include quartz filled pits and vugs, thin brecciated zones (some calcite-healed), calcite stringers and occasional slickensides (usually on the shallower, dipping foliation joint-set). Rock quality, in general, can be assessed from core recovery and RQD. The four borings are scattered throughout the Central Quarry area and together represent general rock quality conditions for the elevation interval investigated. Core recovery in the borings varied from 59 to 100 percent and averaged an excellent 97 percent. Core RQD varied somewhat with each boring location in the quarry with respect to bedrock structure. Specifically, CH-CR4 was intentionally located near the axis of an anticlinal fold to evaluate rock quality where poorer rock quality could be expected due to drilling in the axis of a fold feature. Core RQD for the four core borings was calculated as follows: Boring ROD Ran eg (%) Average RODM CH-CR1 23 - 83 52 CH-CR2 27 - 100 73 CH-CR3 14 - 88 62 CH-CR4 0 - 79 36 These RQD values are considered artificially low due to inclusion of data from rock core within the blast halo from overlying excavation lifts (the upper approximately 20 ft from ground surface in each boring). Making a judgmental allowance for this fact and recognizing the expected low RQD in CH-CR4, Haley & Aldrich believes a representative RQD for the rock mass in general in the Central Quarry based on M8267.200 3