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Clay Report and a 115 cfs capacity were considered for the two alternative reservoir sizes presented in <br />the next section. Three conveyance alignments were considered for both capacities, resulting in six <br />conveyance system configurations. <br />Two gravity-flow systems and one pumped-flow system were considered in this study. Both of the <br />gravity flow alignments divert water from the Gunnison River just east of Orchard City to provide <br />sufficient head to convey flows from the diversion to the proposed reservoir. A diversion structure in <br />the Gunnison River will be required for both of the gravity flow conveyance systems. The concept <br />(location and height) presented in the Clay Report was used in this study. Geologic conditions along the <br />proposed conveyance alignments from the diversions on the Gunnison River to the proposed Grand <br />Valley Dam and Reservoir site have been reviewed and are characterized below in Appendix B based on <br />review of published and web-accessible data and a site reconnaissance conducted on April 30 and May <br />l, 2009. Potential geologic hazards are identified and described in Appendix B. Geotechnical <br />considerations related to design and construction of the proposed conveyance facilities are discussed in <br />Section ll.B. <br />Based on available information reviewed for this study, site reconnaissance, and experience with other <br />sites in similar geologic settings, it does not appear that there are any fatal flaws to construction of the <br />conveyance facilities proposed to supply the Grand Valley Dam and Reservoir. Information in the Clay <br />Report was used herein to facilitate apple-to-apples comparisons to the extent possible <br />Dam Alignments and Appurtenant Structures <br />Two dam alignments at the reservoir site identified in the Clay Report were investigated to bracket a <br />range of reservoir sizes. The normal maximum reservoir water surface elevation for both alignments <br />was set at 4990 MSL. The capacities of appurtenant structures (spillway and outlet works) were based <br />on Colorado Office of the State Engineer (SEO) regulations. Table E.1 summarizes the two dam <br />configurations. <br />Table E1. Summary of Dam Configurations <br />Alignment Approximate Reservoir Storage Embankment <br />Dam Hei ht, ft Volume, Acre-ft Volume, d <br />1 200 154,000 14,100,000 <br />2 l45 39,800 6,680,000 <br />AECOM — <br />2/22/10 <br />' <br />