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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />SECTION THREE <br /> <br />Project Description <br /> <br />complete because it takes approximately three days for water to travel from the Purgatoire River <br />to the reservoir. Losing the ability to regulate, store and release water on demand from the <br />reservoir will waste water, time and money. <br /> <br />Without this reservoir, a new canal around the reservoir and a drop structure would have to be <br />constructed and breaching and reclamation of the existing facility would be required. <br /> <br />Construction of a direct flow canal around the reservoir would also cause significant operational <br />problems with the more than 3 days of travel time for canal flows, and would resulrin a <br />significant increase in waste of water. Consequently, a regulatory reservoir would also need to <br />be constructed. Lastly, the reservoir also provides flood protection for the Model Ditch. The <br />ability to detain storm flows in the reservoir reduces the storm flow into the Model Ditch, which <br />benefits all landowners downstream of the dam. <br /> <br />Based on the remote location of the darn, there is a low risk ofloss of life in the event of a dam <br />failure. Therefore, the dam is currently classified as a Class III hazard structure by the Colorado <br />State Engineer's Office. The dam is classified as an Intermediate size structure based on the <br />height and storage volume. The required spillway capacity for a Class III hazard, intermediate <br />sized dam is a 100-year recurrence interval event. <br /> <br />3.2 RESERVOIR CAPACITY <br /> <br />The reservoir capacity table was estimated using the design drawings dated 1909, based on the <br />surveying at the outlet works conducted in 1998, and in the 1986 spillway modifications, <br />assuming a maximum reservoir elevation of 5750.2 (spillway crest elevation). The storage <br />capacity table from the 1909 design drawings, and adjustments to account for the estimated <br />current silt level in the reservoir are shown in Table 3-1. In order to accurately estimate the <br />current reservoir capacity; a survey ofthe reservoir basin will be completed in the near future. <br /> <br />URS Breiner Woodward Clyde <br /> <br />6800044333.00IR2.doc 1/31100(3:18 PMj/PROJECTS 3-2 <br />