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;Z <br />2? -n <br />Rick Anderson n <br />DIRECTOR <br />ADAMS COUNTY <br />. .'•.. <br />V to <br />+ ( a.c.. IUI-L. ib <br />Parks & Community Resources Department <br />9755 Henderson Road <br />Brighton, CO 80601 <br />PHONE 303.637.8000 <br />FAx 303.637.8015 <br />www.co.adams.co.us <br />?UN 2Q?Q June 22, 2010 <br />Colorado Division of Reclamation, Mining, and Safety <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />I)K*ign ci RscjQma lion, <br />gnirg, and SafetY <br />RE: Technical Revision Request - Mining Permit No. M-1982-147, Mann Lake Pits <br />Adams County would like to request a Technical Revision to mining permit M-1982-147 <br />for the Mann Lake Pits (the Site) located in Adams County, Colorado. The pits are <br />roughly bounded by 124'" Avenue to the north, 120a` Avenue to the south, the Brantner <br />Ditch to the west, and the South Platte River to the east. <br />Lafarge has completed gravel mining operations at the Site and the mining permit has <br />recently been transferred from Lafarge to Adams County. Adams County plans to develop <br />the site as a regional park with three water storage reservoirs. <br />The purpose of this Technical Revision request is to update the mine permit to show the <br />current interconnect design in lieu of the original "spider" design currently included in the <br />Permit. The "spider" design would have connected the three lined reservoirs through <br />interconnected piping located just south of Park Boulevard and between Lakes 1 and 3. <br />The proposed interconnect design includes two connection pipe lines (an upper and a <br />lower) between Lakes 1 and 2, two connection pipe lines (an upper and a lower) between <br />Lakes 2 and 3, and an interconnect pipe to Mann-Nyholt Lake. The lower pipe lines will <br />be controlled with heavy duty slide gates connected to concrete operational structures <br />located at the top of bank. The upper pipe lines are equipped with box inlet structures with <br />trash racks set at the design water surface elevation for each lake. The interconnect system <br />will allow for equalization of storage between each lake and maintain the design water <br />levels in each lake. <br />The revised design also includes grouted boulder rundowns located in the south corner of <br />Lake 1 to drain the future parking lot, along the southeast bank of Lake 1, and along the <br />south bank of Lake 3. An overflow spillway is provided in the north corner of Lake 1 <br />which will outlet to the South Platte River. Wave protection will be provided along <br />erosion prone segments of the lake banks. Wave protection will consist of a layer of Type <br />L riprap placed atop bedding material or filter fabric. The major components of the <br />proposed interconnect system are shown in Figure 1. <br />Page 1 of 2 <br />W. R. "Skip" Fischer <br />DISTRICT 1 <br />BOARD OF COUNTY COMMISSIONERS <br />Alice J. Nichol <br />DISTRICT 2 <br />Larry W. Pace <br />DISTRICT 3