C150259 Approval letter - Laserfiche WebLink

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Background The District owns and operates Empire Reservoir located west of Fort Morgan in Weld and Morgan Counties, between I-76 on the south and US Highway 34 on the north. The District provides irrigation water to a 19,200-acre service area in Morgan County, located between the reservoir and the City of Fort Morgan. The District is a taxing district that levies a tax per acre based on benefits received, not an ad valorem property tax. Water stored in the reservoir is delivered to users througr� a sister company, Bijou Irrigation Company (Company), which operates and maintains the distribution system, used for either direct irrigation or exchanges. Empire Reservoir is an off-stream reservoir constructed in 1905. The dam is a Class 1 Dam with a height of 35 feet and a crest width of 16 feet. There are essentially four separate dam embankments that impound water, they are; the Outlet Dam of 2,300 feet, the Northwest Dam of 1,900 feet, the McIntyre Dam of 4,100 feet, and East Dam of 12,500 feet. The reservoir was restricted by the State Engineer's Office (SEO) from 1985 to 2007, due to the lack of an emergency spillway. In 2006 the District obtained a CWCB loan to construct an emergency spillway, which was completed in spring of 2007, and the reservoir was allowed to fill to its full gauge height 30.0. In the fall of 2007, the reservoir was restricted again to gauge height 29.0 by the SEO, due to additional safety concerns. These concerns were the result of significant wave erosion occurring along the East Dam, resulting in sections of the existing parapet wall failing and significant erosion occurring along the toe of the dam embankment. Discussion Due to additional work not budgeted in the original cost estimate, weather conditions, proj ect location, and unforeseen variations in cost for specific items during construction, the overall cost of the project has increased significantly. To address the 2007 restriction, the District hired Applegate Group, Inc. to prepare construction plans for the rehabilitation of the East Dam. The construction plans were approved by the SEO in December 2007. Given the late December 2007 approval, the District was faced with a difficult decision of either delaying construction until the fall of 2008 or placing temporary fill over the east embankment with SEO approval, therefore allowing the District to fill to gauge height 30.0 and recovering an additiona12,700 acre-feet of storage. Given the economic impact of reducing the available water by 2,700 acre-feet, the District elected to place temporary fill along the east embankment, with the understanding that this material would have to be removed and placed again in accordance with the design specifications in the fall of 2008. The cost of placing the temporary dam embankment was approximately $385,000 or about $143 per acre-feet of reclaimed storage. During the summer of 2008 the District's design engineer, re-evaluated the initial idea of just repairing the 1,250 feet of existing concrete parapet wall. The District did not want to get into another position of having the reservoir restricted due to the failure of any portion of the existing parapet wall. Given the age and condition of the existing wall, the design engineer could not effectively address the District's concerns without replacing the entire concrete parapet wall. Based on the engineer's evaluation, it was determined to be more economical to remove the entire concrete parapet wall and replace it with a sloped rip rap section, consistent with the configuration of the reconstructed East Dam. The cost of removing the concrete parapet wall and reconstructing the dam embankment is estimated at $422,000 and is currently under construction.