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Ms. Erica Crosby, Division of Minerals and Geology <br />March 23, 2005 ~~ <br />Page 10 <br />Z3. Exhibit 6 of 7 depicts future reservoir interconnect pipes to connect al! three ponds arfeP~' ~ i e E s ~u e c e s, u c <br />future water conveyance pipeline to fhe South Platte River. The operator will need to provide <br />detailed designs and drawings for these future pipelines. !n addition, the applicant wf!! need <br />to obtain notarized consent forms between the applicant and the owners of the property and <br />structures to install the interconnect pipes under Weld County Roads 6.23 and 8 and Highway <br />83. <br />The interconnect pipes and the conveyance pipeline have been removed from the Reclamation Plan <br />Maps. The future water storage owner may or may not want to connect the reservoirs. The future <br />water storage owner will be responsible for the reservoir operation and any outlet works designed for <br />reservoir function. <br />Z6. Please explain how the clay will be placed fn the pit to ensure stable slopes. !n particular, <br />please explain how lifts will be placed and compacted to ensure the material is placed in a <br />stable configuration. <br />Embankment Geometry <br />The project plan is to essentially excavate all the soils on the interior of the site and into bedrock to <br />create the reservoir basin. The reservoir bottom will consist of a graded level bedrock surface, <br />positively graded with a slight slope to the outlet. The slope liner is essentially a homogeneous <br />embankment with the below grade portion constructed of clays primarily derived from claystone <br />bedrock. The crest width will be 12 feet with a 4:1 horizontal to vertical (H:~ upstream slope from <br />the crest that terminates at the top of bedrock. The upstream slope will terminate at the top of <br />existing bedrock and a 25-foot wide horizontal bedrock bench. The bedrock bench will be graded to <br />a 6:1 slope to the reservoir bottom. <br />Material Processing <br />The claystone will be processed in place to within ±2% of optimum moisture. The claystone will be <br />ripped in place to a depth of approximately 1' by shanks on a D-8, or comparable. Water will be <br />injected into the ripped zone through tines on a water truck that will also mix the claystone. The <br />processed bedrock will be transported to the slope liner by graders that will strip approximately 4" of <br />the material over a large area, further mixing the bedrock. <br />Foundation <br />No material shat! be placed in any portion of the embankment until the foundation for each section <br />has been dewatered, stripped, suitably prepared, and has been approved by the Engineer. A <br />foundation check sheet shall be signed by the Contractor and Engineer before soil placement. All <br />cavities, depressions and irregularities, within the area to be covered by embankment and which <br />extend below or beyond the established lines of excavation for dam embankment foundations, shall <br />be filled with embankment materials as specified for the ovedying embankment. The weathered <br />claystone bedrock shall be stripped to a depth of at least 1' beneath the slope lined Weathered <br />claystone contact. Care shall betaken that slabs of bedrock are not dislodged during the foundation <br />bedrock stripping. The entire foundation shall be rolled and compacted with a sheepsfoot compactor <br />prior to placement of the first lift of slope liner soil. A smooth drum roller shall not be used to compact <br />the claystone foundation. <br />Cutoff Trench <br />The cutoff trench shall extend 4' below the foundation surface measured after the weathered or top 1' <br />foot of bedrock is removed. After excavation a sheepsfoot compactor should be used to compact the <br />bottom and sides of the cutoff trench before embankment soil placement. The suitability of each part <br />