Imperial Irrigation District
The All American Canal provides drinking water for nine cities and irrigates over 500,000 acres. It is the largest irrigation canal in the world, carrying up to 26,155 cfs. Approximately 68,000 acre feet of water were being lost annually by seepage along a 23-mile stretch of the canal that passed through the great Algodones Sand Dunes. As part of California’s Colorado River Water Use Plan, the All American Canal Lining Project was undertaken to concrete line the 23 miles of the canal in order to conserve the water.
Dahl Consultants’ Principal, Wayne Dahl*, served as Project Manager and Engineer of Record for the design and design support during construction for this 23-mile long, 10,155 cfs concrete lined canal. The team overcame the challenge of keeping the water flowing in the canal during construction by designing and building a parallel canal directly adjacent to the existing canal.
There were four primary challenges: (1) resolution of an economical alignment through the Algodones Sand Dunes, (2) the need to make live tie-ins to the existing canal at nine locations including three drop structures, (3) the discovery that the groundwater mound under the canal had risen significantly between the time the EIS was completed and the design commenced, and (4) news from the Bureau of Reclamation that it could not assure funding for the Drop 2 reservoir.
Our team, working closely with IID and its partners, addressed each of the above challenges. The canal was realigned around the Algodones Sand Dunes, saving 20 percent of planned excavation; tie-in strategies were developed; a large area dewatering scheme was devised; and the old Reach 2 was converted to an offline reservoir.
During construction another challenge arose regarding sediment transfer. Our team worked with IID, the AACLP Coordination Committee (Committee), and the contractor to quickly develop a solution that involved a slightly revised alignment, new designs for transitions at the crossover to reduce construction time, construction of temporary jetties to stop erosion of the banks, and a re-sequencing plan to provide a transfer of flow from the old canal to the new canal one year earlier than planned.
In addition to overall project design, project management included close coordination with Reclamation, collaboration and interfacing with the Committee, conducting workshops, and environmental coordination.
* Work completed primarily while with another firm.