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a <br />SANDSTONE QUARRY <br />Currently, there are no plans to mine the sandstone area. If desired, a technical review and bond <br />calculation will be submitted. <br />The sandstone quarry plan involves the extraction of decorative and building stone from a 3-acre <br />site located within the Dakota Group of sandstones and shales. A small operation extracting <br />dimensional materials is planned. The operation would use limited drilling and blasting and <br />possibly the "feather and wedge" method to remove blocky sandstone product from along the <br />exposed bedding planes. These bedding planes only dip 30 degrees to the west and are only one <br />to several feet thick. Conventional mine benches such as those noted in the granite quarry will <br />not be used. Access ramps to the upper areas of the sandstone outcrop and level loading areas <br />will be developed. There will be no remaining highwalls and any final slopes will be no steeper <br />than 1:1. Vertical lifts are typically expected not to exceed much over 8'. The sandstone <br />materials are siliceous rich materials with typical desert varnish (dark) and reddish yellow oxide <br />staining on the surface. No metal bearing minerals are present that might result in causing any <br />AMD conditions. No phosphate bearing rock units were noted in any of the proposed mining <br />areas. (Azurite, Inc., 11/97) <br />MINING PLAN <br />The site appears to have been previously mined in a small area for sandstone. No records of <br />such a mine could. be located. The easily split sandstone will be mined by drilling and wedges as <br />well as minimal blasting. Sandstone product preparation includes size separation or sawing or <br />splitting blocks into smaller or thinner blocks. Some sandstone maybe mined and transported to <br />one of the project's crushers to crush into decorative rock products. <br />The 3-acre sandstone quarry, on the north side of Tallahassee Creek, will be developed in the <br />Dakota Formation of sandstone, a medium to coarse grained silica rock exposed on the surface. <br />The rock has little to no overburden and dips to the west at about 30 degrees. The bedding plane <br />lamination within the sandstone unit varies in thickness from one to several feet. These <br />laminations will, to a great degree, control the dimension of the rock product extracted from the <br />site. The rock will be mined in accordance to the bedding plane angle and laminar plane of <br />weakness. Conventional mine benches as planned in the granite quarry will not be employed <br />here. Access ramps to the upper areas of the sandstone outcrop and level loading areas will be <br />developed. The mine plane will result in no final highwalls, no final slopes exceeding 1:1 and no <br />vertical lifts much. over 8'. The stepwise mining following the bedding planes and laminations <br />will produce a final topography less steep and therefore safer than currently exists with the <br />natural highwall cliffs in the drainage channel. No additional geostability analyses were <br />conducted because of these mining and final configuration plans. <br />A new road will be built from the granite plant area to the sandstone quarry. The Tallahassee <br />Creek crossing to the sandstone quarry will be constructed with steel "I" beams resting on <br />concrete bulkheads on either side of the creek. A 40' span will readily allow the unimpeded flow <br />of the Tallahassee Creek (Verkaik 12/97). The new quarry should completely encompass the <br />