Itaipu literally means Singing Stones. The name was given by Gurani Indians to a large rock island on the fast flowing Parana river. Today, on the river stands the world's largest hydroelectic power plant producing a mind numbing 75 million MWh a year. To add to the charm, it also saves approximately 67.5 million tonnes of carbondioxide emission a year, if the same quantity of electricity was being produced by traditional means. The work on the dam started in 1975 and took almost 16 years to complete. In 1991 the dam was fully functional, but in 1984 the first units of the plant started working. The dam is binational and is built with collaboration between two countries Brazil and Paraguay. One of the interesting facts is that in the internal corridors of the dam, there is a thin red line which demarcates the boundaries of the two countries.

As with everything, it was the journey of the sixteen long years that takes the breath away. At the start of the bridge, the nearest habitation was a 1000 miles away and the team building the dam had to start with building a township of nearly 30000 workers from different corners of the two countries. Imagine building a township to house and host 30000 souls! It was the start of a whole new economy - almost a gold rush. After months of geological surveys and painstaking calculations, the work was begun but before the first stone could be laid, the fast flowing Parana river had to be temporarily diverted to a new course. After the succesful diversion, the flow of the river has to be blocked to the site of construction and that was done by stacking massive boulders in it's path.

Some clever engineering aspects was introduced, one of which was the creation of a hollow dam! The power of a dam to stop the water is a direct factor of the weight of solid in the path of the water and the pressure bearing capability of the structure with depth. This is why dams are build to taper outwards with depth. For Itaipu, it was calculated that if the bridge was created solid, the weight of concrete would far bypass the actual weight really required to stop the water and it was decided to create a hollow dam instead of a solid one. This meant that the same amount of concrete could be used to create a dam with far greater base area with a more gentler slope. It also meant that the hollow would provide enough room for the turbines and machinery to be placed inside of the dam.

All went well, but it was soon realized that the height of water after the initially computed height would not hold sufficient potential energy to produce the desired power output. The only option was to raise the height of the dam. Most of the hydroelectric dams in the world are typically built between rock faces which give them support. In case of Itaipu, there was no such rock face and the bridge had to support itself. This meant that the increase the height of the dam to the desired levels, the width of the dam had to be spread out to seven more kilometers. The final length of the dam stands at 7.23 KM.

The biggest hurdle faced during construction was the finding of a strata of decayed rock on the base of the dam. The build a dam of this scale on a strata of poor rock would have been a disastrous decision. The work nearly came to a halt as engineers and geologists struggled to fathom natures surprises. Finally, it was decided to do a root canal operation of the rock. The entire strata was mined out and filled with hyper strong mixture of concrete.

Taking of concrete, there were other surprises in store. By the chemical property of concrete, it results in an exothermic reaction during the settling process. For small chunks, the heat is dissipated to the environment, but for larger structures, the rate of cooling of outer layers is much faster than the core. This would case uneven temperature distribution and result in multiple cracks during the settling process. To circumvent the challenge, it was decided to hyper cool the concrete before pouring it into the holdings. The concrete was cooled to an average temperature of 4 degrees celsius before pouring. Imagine cooling all the concrete required to build a dam of this size!!

Truly the bridge is a marvel of engineering and the human spirit!