Yacyretâ Multi-Purpose Project

"Constructing Hydropower Plants"

What's the best way to design and build South American hydropower facilities with fish passages, irrigation facilities, a navigation lock and recreational areas?

MWH faced this challenge when it led an international consortium of engineering firms through the planning, design and construction management of the 3,200-MW Yacyretâ project on the border of Argentina and Paraguay.

Equipped with a 20-unit powerhouse, the project uses some of the largest Kaplan turbines ever manufactured. The 160-MW maximum capacity Kaplan turbines have a runner diameter of 31 feet (9.5m). These turbines discharge a total of 500,000 ft3/s (14,000 m3/s).

Facility Specifics

The project entails more than 40 miles (65 km) of embankment dams. The first unit was commissioned in 1995; the project was fully operational in 1998. Yacyretâ features:

• Two 131-foot-high (40-m)
• Three-mile-long (5 km) closure dams
• Thirty-seven miles (60 km) of embankment dams with a max height of 134.5 feet (41 m)

The foundation seepage cutoff is provided by a 35-mile-long (56-km) cement bentonite slurry trench and grouting.

Two spillways have a combined capacity of 3.4 million ft3/s (95,000 m3/s). The main branch spillway is equipped with 18 radial gates — each 49 feet wide by 66 feet high (15m by 20m). The second spillway is equipped with 16 gates — each 49 feet wide by 51 feet high (15m by 145.5m).

Five hydraulic models were constructed and tested. The 3,900-foot-long (1,189-m), 253-foot-wide (77-m) indoor powerhouse consists of 20 units with skeleton bays for an additional 10 units.

The 20 generating units — each rated 172.5 MVA at 0.9 PF — will be connected to the Argentine transmission network at 500 kV and the Paraguayan transmission network at 220 kV. The switchyard, a 13.2/220/500 kV, SF6 gas-insulated substation is provided on the draft tube desk of the powerhouse.

The 886-foot-long (270-m), 89-foot-wide (27-m) navigation lock will lift a six-barge tow as much as 79 feet (24m) in 16 minutes.