Bento Munhoz Hydroelectric Plant

The Governor Bento Munhoz da Rocha Netto Hydroelectric Plant, formerly known as Foz do Areia, is dam and hydroelectric power plant on the Iguazu River near Foz do Areia in Paraná, Brazil. It is the furthest dam upstream of the Iguazu Falls and was constructed between 1976 and 1980. The power station has a 1676 MW capacity and is supplied with water by a concrete face rock-fill embankment dam.

As their main power plant, it is owned and operated by Copel who renamed it after Bento Munhoz da Rocha Netto, governor of Paraná between 1951 and 1955.

History
In May 1973, Copel was awarded the concession contract to construct the dam and by May 1974, various studies had recommended a site near the confluence of the Inguazu and Da Areia Rivers. By August of that year, a design was chosen and in October 1976 after contracts were awarded, construction began. The river was diverted with two 12 m diameter and 600 m long diversion tunnels. To facilitate the river's diversion, two cofferdams were constructed, one upstream and one downstream of the site. The upstream cofferdam was 45 m high and allowed the diversion of up to 7700 m3/s of water. The dam began to impound the reservoir in 1980 and by October it was filled and complete.

At the time of completion, the dam was the tallest and largest concrete face rock-fill dam in the world. It was also the first of its type to have a reservoir of its size. The techniques to construction the dam were instrumental and an advancement as 50000 m3 of fill was placed each month for two years in a row. The stability and integrity of such a large dam with a large reservoir helped bring confidence to its specific design.

Dam
The Bento Munhoz da Rocha Netto Dam is an 828 m long and 160 m high concrete face rock-fill type. The dam contains a total 14138000 m3 of material which includes 14000000 m3 of rock-fill and 138000 m3 of concrete. The dam's spillway is controlled by four 14.5 m wide and 19.5 m high tainter gates. It has an 11000 m3/s capacity and is 400 m long and 70.6 m wide. Water is brought towards the power station intake through a channel which is 450 m long and 90 m wide. The actual power intake structure is 70 m high, 108 m wide and allows for a maximum reservoir level depletion of 47 m. Six wheel-type gates facilitate bring water into the power station. An additional gate exists for maintenance purposes.

Power station
From the intake, six 220 m long penstocks deliver water to the generators as their diameter reduces from 7.4 to 7 m. The power station contains four 419 MW generators for a total installed capacity of 1476 MW. Space for an additional two generators exist and if installed would bring the plant's total installed capacity to 2511 MW.