Construction Practices at a Year-Round-Delivery Irrigation District

The Imperial Irrigation District (IID) is located in the southeastern desert area of southern California. It is the largest irrigation district in the United States, importing over 85,000 cubic meters (3 million-acre feet) annually of Colorado River Water to irrigate 227,300 hectares (500,000 acres) of farmland. The IID has an extensive irrigation delivery system consisting of 2,575 kilometers (1,600 miles) of lined and unlined canals and an equally extensive drainage system comprised of 2,335 kilometers (1,450 miles) of open surface drains. The uniqueness of the irrigation district is that it provides year-round irrigation delivery and drainage services to its agricultural customers. The IID's infrastructure system is extensive, consisting of 1,930 kilometers (1,200 miles) of concrete lined canals, 182 kilometers (113 miles) of pipelines, 750 irrigation and drainage pumps, and over 15,000 associated canal and drainage structures consisting of checks, deliveries, siphons, bridges and spillways. Replacement and maintenance of this extensive infrastructure can be a challenge under the conditions of a year-round water delivery system. Irrigation canal outages for either construction or maintenance activities are permitted for only 3 and 5 day periods, depending on the complexity of the planned work. These short duration water outages are the maximum time allowed to avoid crop damage from lack of water. Drainage canals on the other hand have no ability for water outages due to the extensive and continual inflow of subsurface (tile) drainage system discharges. Work associated with construction and/or maintenance activities within drainage channels must be done while working around this constant flow condition. Because of the year-round delivery of water IID has had to be adaptive, developing unique and innovative methods to perform its construction and maintenance activities. This paper will overview how the IID addressed these "working-in-the-wet" issues in the construction of three recently installed projects.