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PHILLIPS MINING, GEOTECHNICAL 8 GROUTING, INC. <br />1. INTRODUCTION <br />The Homestake Mining Company (Homestake) proposes to close the 93601.evel Adit of <br />the Bulldog Mine with the construction of a mass concrete plug. <br />The following Scope of Work outlines the preliminary configuration of the plug and the <br />general procedures that should be utilized for the construction of the plug. In particular, <br />those areas are highlighted where particular care must be taken to ensure that the plug is <br />constructed safely and that its eventual performance is optimized, so that the final product <br />is one that can safely withstand the applied hydrostatic head with the minimum of leakage. <br />The contractor that is chosen for the construction of this plug must demonstrate that, as a <br />Company, it has prior experience in this type of work and that the senior field personnel <br />that will be assigned to the project have the necessary expertise in all phases of the work. <br />2. BACKGROUND AND EXISTING CONDITIONS <br />The initial excavation of the adit commenced in September 1966. The cross section of the <br />excavation is about 14 ft. wide by 10 ft. high. Excavation from the portal for a distance of <br />approximately 1200 ft. was performed in the Creede Formation, consisting of completely <br />altered boulders in a matrix having high clay content. <br />The initial 350 ft. (approximately) of the adit was advanced using the digging capabilities <br />of a mucking machine. Blasting, initially to break boulders, was used beyond this point. <br />Full sets were required throughout this section from the portal, in order to provide <br />adequate support in the poor ground conditions. <br />Page 1 <br />