The overall project comprises four caverns, three with a storage capacity of 330,000 cubic meters, and one with a storage capacity of 150,000 cubic meters. Cavern lengths vary from 885 to 1,250 feet (270 to 380 meters). The facility also includes interfaces for connecting tunnels from the start-up galleries, operations tunnels, access tunnels, maintenance chambers, an operations shaft, tunnels for the water curtain system, and other permanent structures inside the access shaft.
WSP was appointed to undertake design and construction supervision services for the underground caverns, as well as the associated underground and aboveground facilities for Phase 1 of the project. Responsibilities included civil and geotechnical design of the caverns and associated tunnels, construction supervision, and review and validation of the basic engineering design provided by the owner.