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<br />COLORADO WATER CONSERVATION BOARD <br /> <br />WATER SUPPLY RESERVE ACCOUNT <br />2006-2007 GRANT APPLICATION FORM <br />SAFETY AND SERVICEABILITY NEEDS INVENTORY <br />FOR RESERVOIRS IN THE LEROUX CREEK DRAINAGE BASIN <br /> <br />OVERVIEW SUPPLEMENT <br /> <br />The project is located in Delta County, north of Hotchkiss. Surface waters in the drainage basin <br />consist of Leroux Creek and its tributaries. A map is included in this supplement showing the <br />location of the drainage basin and service area. There are currently 150 water users who apply <br />stored water from the subject reservoir system to lands in the Leroux Creek and Redlands Mesa <br />area. The reservQirs serve as the primary water supply for over 4500 acres of valuable orchard <br />and hay land which produces more than $3.5 million in direct economic benefits. Agricultural <br />use includes orchards, vineyards, hay and small grains. Orchards in the area produce 300 to 600 <br />bushels/acre and hay production is about 3 tons per acre. The system's water storage also <br />provides domestic water for the Town of Hotchkiss, Rogers Mesa and Hanson Mesa. <br /> <br />The LCWUA has initiated a program of identifying and prioritizing rehabilitation/upgrade needs <br />in order to enhance the safety and reliability of the dams within their system. The project for <br />which funding is requested involves making a preliminary inventory of the needs for 28 of the <br />dams (Carl Smith has been excluded because of its recent rehabilitation). A list of the project <br />dams along with estimates of their respective storage capacity is also included with this <br />supplement. Generally, the needs can be placed in one of the following categories, in this order <br />of priority: <br /> <br />1. Outlet Works - Deterioration of outlet components such as pipes and gates is one of the <br />greatest safety and serviceability concerns for all dams, particularly older ones which may <br />have un-protected steel pipes. Erosion and removal of embankment or foundation <br />material along the outside or into and through the pipe can result in sudden catastrophic <br />failure even for dams that have had a long history of stability. Additionally, the risk is <br />increased at some of the project dams which have downstream control valves. <br />Downstream valves pressurize the outlet pipe. Therefore, the proposed work includes <br />focusing attention on the outlet systems for all of the dams. <br /> <br />2. Seepage - Uncontrolled seepage, particularly seepage which exits on the embankment, at <br />the embankment/foundation contact, in the foundation slightly downstream from the toe <br />of the embankment or along the outside of the outlet pipe, is of a concern. If the seepage <br />forces or pressures are great enough, material can be eroded from the embankment or <br />foundation, or the pressures can de-stabilize the dam slopes. Methods to address seepage <br />range from channeling and measuring to installation of filters and drains. The proposed <br />work includes identifying significant seepage areas. <br /> <br />3. Slope Stability - As experienced with the Carl Smith failure, a long history of <br />embankment stability does not assure either perpetual security or adequate safety factors <br /> <br />1 <br />