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Overburden exists to an average depth of approximately 10.4 feet over the northern <br />amendment area and to an average depth of 7.2 feet over the southern site. Overburden <br />needed for construction of the final reclamation slopes will remain on-site. Overburden in <br />excess of that which is needed for reclamation may be sold and removed from the site. <br />Mining at the site will be to bedrock. Regional geologic mapping indicates near surface <br />bedrock underlying the alluvium is most likely silty sandstone with some sandy shale of the <br />Fox Hills Sandstone. The average depth of sand and gravel over the northern site is 28.7 <br />feet and average depth of sand and gravel over the southern site is 12.7 feet. The deposit <br />is classified as a wet alluvial deposit. Groundwater depths in borings on the southern <br />deposit were typically 4 to 6 feet below the ground surface. Groundwater depths in <br />borings on the northern deposit were typically 14 to 19 feet below the ground surface. <br />The primary commodity mined is aggregate and a secondary commodity may be gold. <br />Aggregate from this facility is supplied to local, county, and state governments, as well as <br />private industry. If gold is to be mined it will be used for commercial purposes. <br />Methods of Mining <br />The typical mining procedure for all phases will be as follows. Any areas slated for <br />protection will be identified in the field to assure that mining operations will be set back as <br />appropriate. Mining offsets from areas designated for protection and from structures not <br />owned by Al will be maintained in accordance with the Geotechnical Slope Analysis <br />included in Exhibit S. Setbacks were determined for each boundary and vary from 40 feet <br />to 75 feet from structures. Al will not relocate any structure not owned by Al nor any water <br />conveyance without first consulting with the structure owner regarding the new location <br />and design. <br />Initially, topsoil and overburden will be stripped from a phase with scrapers or a dozer and <br />placed separately in temporary stockpiles within the permit area (see Exhibit C Mining <br />Plan). The topsoil will be segregated and stored separately from the overburden material <br />as required by Rule 3.1.9(1). Topsoil stockpiles remaining in place for more than one year <br />will be protected from wind and water erosion by seeding to a dryland grass or other <br />appropriate cover crop. Stockpiles are incorporated into a weed control program which <br />consists of regular inspections and, if necessary, mechanical and/or chemical treatments <br />in the applicable fall and spring seasons. <br />Overburden stockpiles will be continuously rotating. Once the deposit has been mined <br />from the stripped portion, the temporary stockpile will be removed and used for <br />reclamation. The remaining portion of the cell will then be stripped and the overburden will <br />be stockpiled on the mine floor or placed immediately in the reclamation slope. There will <br />be no permanent stockpiles at this site. Extra overburden will be used to create additional <br />wetlands and undulating shorelines or may be sold and hauled off site. <br />Riverview Resource <br />Amendment to Permit M1999098 112c <br />Page D2 of D6