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<br />solutions to stabilize the wall. Pit wall stability will be <br />maintained through construction of a rock buttress composed of <br />interburden waste rock materials. The preliminary buttress design <br />is shown on Figure E.3.1-2 and discussed in revised Section <br />E.3.1. Final design for the buttress will be determined when the <br />exact characteristics of the south wall and seepage through the <br />south wall are known, in the first two years of mining along the <br />south wall or when the weak constituents of the wall have been <br />fully exposed and submitted to the Division for approval. <br />If seepage management operations indicate that there is a <br />potential for large volumes of seepage which may affect the long <br />term stability of the rock buttress, a low permeability barrier <br />such as a slurry wall or cutoff trench will be installed through <br />the alluvium and keyed into the underlying Santa Fe Conglomerate <br />to cut-off seepage through the alluvium. The preliminary design <br />is shown on Figure E.3.1-2. BMR will evaluate the need for the <br />low permeability barrier during the first two years of mining in <br />the south wall area. If the barrier is determined necessary, BMR <br />will submit final designs to the Division for approval. <br />The stratigraphy, material characteristics, ground water <br />conditions and analytical methods which form the basis for the <br />preliminary design of the buttress and low permeability barrier <br />were determined from the initial drilling program and a drilling <br />program conducted in the fall of 1988. <br />By implementing the placement of a~rock buttress and committing <br />to evaluating the need for a low permeability element BMR <br />believes that long term stability of the proposed post mining <br />configuration can be ensured. <br />Section D.3 Waste Rock Disposal <br />Section 0.3.1 General <br />6. Does cross section A-A', illustrated in figure 0.3-4, refer to a <br />specific figure, or is this an idealized cross section? <br />Response: Cross section A-A' refers to Figure D.3-2. A cross section <br />location has been added to Figure D.3-2. <br />Section 0.3.3.2 Waste Rock Geochemistry <br />7. Please specify the location and depth of each waste rock sample taken. <br />This information will help us to make a determination as to the sample <br />significance. <br />Response: The drilling logs for each sample are enclosed along with a <br />information on the approximate interval from which a composite <br />sample was taken. The drill logs include a coordinate location <br />for each hole. BMR requests that the drill logs be held <br />confidential in accordance with C.R.S. 32-34-112(9) <br />BMR geologists selected the core based on criteria established <br /> <br />