[img]2016m3x/ct_eyyjsbz2014j_eyyjsbd_0305_20163[/img] ITAIPU DAM: Vi

In this section, you will hear a short passage. For questions 21 -30, complete the notes using three words or fewer each blank. The passage will be read twice. Remember to write the answer on the answer sheet.
    Hello and welcome to this, the fourth in our series of public lectures on Big Buildings. Today we’re going to take a look at the Itaipu Dam in South America. You may not know too much about Itaipu but it’ s been named one of the "Seven Wonders of the Modern World" by the American Society of Civil Engineers. And in this lecture, I hope to explain some of the reason why.
    Ok, let’s begin with a few facts. First of all, where exactly is the Itaipu Dam? Well, it’ s on the Parana River, close to the border between Brazil and Paraguay. Construction began in 1975 and the dam was only finished in 1982. Two years later it started generating electricity and its now one of the largest hydro-electric power plants in the world. The total cost of the building was 20 billion dollars.
    In design, it’s what is called a gravity dam, which means it relies on its immense weight for stability. The main section is made of concrete actually 15 times the amount of concrete that was used in creating the Channel Tunnel between England and France.     To give you an idea of size, the dam is 7. 8 kilometers long, with a height of 196 meters. The reservoir behind the dam is huge—almost fifteen hundred square kilometers and the reservoir capacity is 1. 02 trillion cubic feet. The dam really is an amazing feat of engineering. Engineers actually had to change the course of the Parana, which is the seventh largest river in the world, and move 50 million tons of earth and rock in the process?
    With any success story, I suppose there are bound to be a few problems. One is that the Itaipu Dam sometimes gets blocked with mud and silt, which is expensive to clear. But more seriously, this mud and silt carries bacteria, which can be transmitted in the water and cause illness in the people who use it. The other main problem was that when the land was originally flooded to create the reservoir, they destroyed a large area of rainforest, which was home to many birds and other forest creatures and sadly they died. Since then, however, seven new protected areas have been created for wildlife.
    Ok, now let’s look at the construction of the dam. Can you see the point at the very bottom of the dam on the upstream face? That’s called the heel, just like part of your foot. And at the same point at the bottom of the downstream face of the dam is called the toe, also like the toe on your foot. On the top of the dam, that’s the part you can see above the water, the "crest" , and the base or ground on which the dam is built is the " foundation". I think that’s all you need to know for now.