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• WHEXSIopeEvaluation AdrianBrown <br />5. STRUCTURE <br />Structural information was obtained for the WHEX project from oriented core/video logged holes. To <br />date a total of 9 geotechnical holes have been drilled and logged in the mine area. Orientation <br />information is provided for each drill hole in Appendix B. <br />5.1 Joint direction <br />Structural information obtained from the holes can be summarized as follows: <br />1. Volcanic Rock. Structure in the volcanic rocks in the WHEX walls is different from the structure <br />in the rest of the diatreme. There is little evidence of the dominant vertical joint and fault system <br />in the rest of the diatreme, and there is a dominant apparently orthogonal pair of jointsets dipping <br />between 20° and 60° in both directions azound a strike that varies from east-west in the north of <br />the mine, to northeast-southwest at the south of the mine. These joints are directions that are <br />adverse to the west wall and the north wa11(which is where the volcanic rocks will be <br />encountered in the wall). This joint behavior appears to die out with depth and towards the north: <br />it is largely absent below about 400 feet from surface (which is towards the base of the currently <br />proposed mine) and approaching the county road (which is north of the currently proposed mine). <br />• 2. Granitic Rock. The structure in the granitic rock is dependent on the type of rock. The gneiss and <br />schist rock has strong foliation, for the most part intact. Occasionally there is fracturing or <br />faulting along the foliation. In general the dip of the foliation is directed between west-northwest <br />and west, with dip angles between 30 and 70 degrees. This is adverse for stability of the eastern <br />wall of the mine (and would be for a southern wall in granite; however based on the current <br />geometry the southern walls will be in volcanic rock). <br />5.2 Fracture intensity <br />Fracture intensity is moderate in both volcanic and granitic rock, averaging approximately 1 fracture per <br />foot, and one major fracture (category 2 or above) every 5 feet. There appeazs to be a considerable <br />increase in fracture intensity in both rock types (and reduction in the associated Rock Quality Designator <br />and Rock Mass Rating) at an elevation of approximately 10,000 feet, some 300-400 feet below ground <br />surface. This approximately coincides with the base of the oxidized system. <br />• <br />Report 1385L.200309017 9 <br />