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8. In addition to the updates made to the maps, a Sediment Pond Detail and a <br />Sediment Pond Discharge Detail of the discharge pipeline have been included to <br />show the required specifications. <br />9. Based on a flow of 7,600 cfs for the 10-year 24-hour event, and the cross-section <br />of the river at the narrowest point near the sediment pond the water surface <br />elevation was determined to be 8 feet below the sediment pond. Details and <br />calculations are attached as the 10 Year Cross Section Detail and the Flood <br />Level Calculations. <br />10. As a condition of approval of this Technical Revision, Tri County Gravel <br />commits to providing a complete analysis of the dike repair including bank <br />revetment, boulder sizing, material quality, and a professional engineer certified <br />slope stability analysis demonstrating a safety factor of 1.5 or greater. <br />11. Tri County Gravel commits to having the dike completed by March 31, 2008 and <br />will submit as-built reports to DRMS by April 15, 2008. <br />12. The pit bottom has been modified to leave 2' of gravel above the bedrock. The <br />dewatering pump will be placed 0.5' above the bedrock to prevent selenium <br />oxidization in the groundwater flows. <br />13. Tri County Gravel will be redirecting on site irrigation ditches to provide water to <br />wetlands and riparian areas between the proposed Phase 3 and the Gunnison <br />River. <br />Attached to this response letter are updated maps for the technical revision and <br />replacement pages for the technical revision hard copy in the DRMS office. Please direct <br />any further questions or comments to me. <br /> <br />Ben Langenfeld, Project Engineer <br />Greg Lewicki & Associates, PLLC