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Erica Crosby, Division of Minerals and Geology <br />September 27, 2002 <br />Page Two <br />AGGREGATE <br />INDUSTPIES <br />South Platte River profile indicates that the existing berm is approximately 9.5' above the river invert, <br />meaning that the final grade will be approximately 5.5' above the river invert. The spillway elevation <br />is set at approximately 2.5' above the river invert. The pit floor ranges between approximately 7 and <br />12 feet below the river invert." <br />5. Placement of wash fines in the North Lake area will occur throughout the life of the active mining <br />operation. Backfilling, gading and spillway construction will occur during seasonal low river flow. <br />Wash fines cells will be revegetated with the proposed wetland seed mixture as they are filled. <br />6. Aggregate Industries commits to constructing pitside channel spillways in accordance with approved <br />Urban Drainage and Flood Control District specifications. <br />7. Enclosed are letters of disqualification from the U. S. Fish and Wild Life Service regarding Ute <br />ladies-tresses orchid habitat and Prebles' Meadow Jumping Mouse habitat. <br />8. When the water storage reservoirs are full, water entering the pits from the four offsite tributary flows <br />will pass over the spillways into the South Platte River. The spillways have been designed according <br />to Urban Drainage criteria, based on reservoir surface area. The capacities were checked against <br />estimated developed 100-year flows for the four offsite tributary areas, and found to be more <br />than adequate. Structures will be constructed whenever mining begins to encroach on the no bank <br />stabilization setback enforced by Urban Drainage. If bank stabilization is not constructed, water will <br />sheet flow back to the river over the lowest points along the existing bank. There is no forseeable <br />reason why the grouted boulder rundown channels would impact any manmade structures. The <br />flow rates for the offsite tributaries used in design were obtained from Urban Drainage. <br />If you have any questions regarding the above responses, please call me at (970) 336-6526. <br />Thank you for your consideration in this matter. <br />Very truly yours, <br />L~~N'1GP ~~ ~ ~5~~~ <br />Connie Nickle Davis <br />Support Services Representative <br />Enclosures <br />cc: Adams County Clerk and Recorder <br />Aggregate Industries-WCR, [nc. -Mike Refer, Tom Maul, Casey Jones <br />Connie Nickle Davis, Support Services <br />P. O. Box 337231, Greeley, CO 80633 <br />970-336-6526 Faz: 970-378fi866 <br />