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Traylor Bros., Inc., as part of the Bechtel–Traylor Joint Venture, is serving as prime contractor on the Salt River Project Pumped Storage development for the Salt River Project Agricultural Improvement and Power District (SRP). Delivered under a Progressive Design-Build model, the project supports development of a large-scale pumped storage hydropower facility designed to provide up to 2,000 megawatts of generation capacity and 20 gigawatt-hours of long-duration energy storage to the regional power grid.
The facility is being developed in two 1,000-MW phases. Each phase includes four reversible pump-turbine generating units housed within a shaft-style underground powerhouse constructed near the lower reservoir. The powerhouse will be connected to both reservoirs through a complex underground water conveyance system consisting of hard-rock tunnels, vertical shafts, and caverns excavated using drill-and-blast methods.
The lower reservoir is the existing Apache Reservoir formed by Horse Mesa Dam, while the upper reservoir will be a new 15,000-acre-foot facility constructed on the upper plateau. The upper reservoir includes two concrete-faced rockfill dams and a roller-compacted concrete spillway, with full reservoir development completed during Phase 1. Power generated by the facility will be transmitted to the grid through a new 500-kV switchyard connection.
Traylor’s scope of work includes construction of tunnels and tunnel linings, vertical shafts and shaft linings, underground caverns, cofferdams, dam embankment earthwork, roller-compacted concrete placement, powerhouse construction, and major concrete intake and outlet structures. The work demands precise execution in hard-rock conditions, advanced grouting techniques, and close coordination between underground excavation, structural concrete, and mechanical systems installation.
The Salt River Project Pumped Storage facility represents a critical investment in grid reliability and renewable energy integration for Arizona. The project highlights Traylor’s expertise in underground construction, hydropower infrastructure, and large-scale energy projects delivered in technically demanding conditions.