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<br />Memo to Greae Squire 3 April 12. 2000 <br />6. Are all the man made structures within 200 feet of the affected land illusvated on the Exhibit C <br />map? The list of structure owners contained in Exhibit S to the application indicate that there may <br />be pipelines and communication lines in the vicinity of the proposed pit, but none can be located <br />through review of the map. Mining within 200 feet of critical structures such as gas pipelines may <br />require specialized mitigative measures such as the installation of swain gauges. <br />The general setback of 25 feet from structures discussed in the application and illusvated on the <br />maps is inadequate to assure the stability of the strucrures given the potential depth of the pits and <br />the lack of geologic and geotechnica! information provided. If the drilling logs do not indicate any <br />adverse geologic or hydrologic conditions, the Division could accept setbacks equal to two times <br />the pit depth for most types of structures without any rigorous analysis of stability. The setbacks <br />would be measured as the horizontal distance from the toe of the pit wall. <br />8. The application proposes a reservoir bank with 3:1 slopes from the edge of the bank to ] 0 feet <br />below the water line, then 2:1 slopes below that point. The water surface elevation in water storage <br />reservoirs can flucruate widely. The Applicant must describe how the expected water surface <br />elevation that will be used to establish the 3:1/2:1 slope break point will be determined. The 3:1 <br />slopes must extend to 10 vertical feet below the ordinary low water mark for the reservoirs. <br />9. The application does not address the potential for erosion at the reservoir perimeters. The shale <br />backfill will probably require some armoring to protect it from wave action. The Applicant should <br />address this issue and provide a proposal for armoring and an estimated cost for its installation. <br />,wit, GR9 •J/if/~ <br />10. Disturbance at the south perimeter of Mining Cell 3 appeazs to extend beyond the property line, <br />which is presumably the permit boundary (The permit boundary is not specifically illustrated on the <br />maps). <br />enclosure(s) <br />cc: Cazl Mount <br />c:\windo ws\personal\ri verbend. doc <br />