Original subtitles

it's one of the world's most ambitious

engineering projects a massive

hydroelectric dam generating more

kilowatts than any other on the planet

to build it the path of a mighty South

American River must be blocked thousands

of acres of precious wild animal habitat

and tens of thousands of homes will

disappear in a huge flood 40,000 workers

must battle against the forces of nature

rocketing temperatures the constant

threat of killer floods behind it all

the potential for catastrophe

building the Atty ku'Damm will take

seven tough years and this giant quest

for energy will demand a devastating

price

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[Applause]

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the Rio paraná at 4000 kilometers long

it's South America's second biggest

river out strict only by the mighty

Amazon for part of its course

the Piranha marks the border between

brazil and paraguay here

the rivers path is barred by a man-made

structure via Typhoon Dan it's the

world's most powerful hydroelectric dam

it pumps out 90,000 gigawatts every year

enough to power Britain's capital city

London for over three years

stretching for seven kilometers it's two

and a half times longer than America's

Golden Gate Bridge and stands as high as

a sixty five storey building it's

holding back a body of water nearly 400

times the area of New York's Central

Park water that plummets through the dam

like a giant man-made waterfall to

produce electricity it would take an

army of 40,000 workers and twenty

billion dollars to build this monstrous

structure almost 50 times the cost of

the Hoover Dam italy's pierre assemble

Nellie was one of the dams key engineers

possibly we didn't realize how difficult

the project was going to be it's in one

of the remotest corners of the world but

why were the most ambitious and powerful

dam on the planet be built here it's the

1960s and Brazil is booming its economy

is growing by 10 percent a year but the

population is surging to already over 70

million in three decades Brazil's

population will hit 170 million and

become one of the top ten most populous

countries in the world

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Brazil's growth will create a spiraling

demand for energy the government must

find a way to satisfy the power-hungry

masses of the future or face economic

crisis but how the country hasn't got

enough oil and gas to head off an energy

crisis and it can't afford to spend big

money on fuel imports but then someone

has a brain wave why not use a natural

acid that's free and the Brazil has

plenty of

water the staggering 10% of all the

fresh water in the world is found in

Brazil it's 40 thousand kilometres of

rivers could reach right around the

globe if the vast potential of water

could be harnessed by hydroelectric

technology energy demands could be met

without costly fuel imports Brazil is

thinking big the government wants one

massive dam to supply a huge chunk of

the nation's energy demands finding the

perfect site for such a big dam won't be

easy

the rithm must have a volume of water

great enough to produce the energy

needed it must flow through narrow banks

and it's bedrock must be strong enough

to take the massive weight of the dam

walls this is the obvious spot

the river iguazu feeds one of the

biggest waterfalls in brazil but it had

only 1/8 of the water needed for the

monster dam one by one engineers check

out 50 other sites none make the grade

but finally the perfect location is

found the river piranha is the seventh

largest in the world holding four times

as much water as America's Colorado

River at a spot called it taipu it flows

through a deep underwater Gorge

geological surveys show that the bedrock

can bear enormous weight the engineers

think it's perfect

but there's a huge obstacle the gorge

sits right on the border between Brazil

and it's old enemy Paraguay in the 19th

century the two countries had fought in

a bitter war

araguaia lost half its territory and

half its population was killed

even over a hundred years later there

was still mistrust between the two

peoples 1966 complex negotiations begin

between the two countries for seven

years the dam project hangs in the

balance but in the end the lure of vast

supplies of energy proves irresistible

on the 26th of April 1973 Brazil and

Paraguay finally sign a treaty

via type of damn gets the green light if

everything goes to plan it will outstrip

some of the world's greatest dam

projects it will be 18 times as long as

the mighty Hoover Dam and nine times as

heavy most importantly it will produce

six times as much electricity

but the most powerful hydro dam in the

world will demand sacrifices blocking

the Rio paraná will create a huge

reservoir needed to feed the electric

turbines

it will also submerge the river valley

under 100 metres of water a vast area of

farmland and forest must be flooded to

feed the monster Dam tens of thousands

of people will lose their homes and the

habitats of thousands of animal species

will disappear forever as the entire

pool project reaches the point of no

return

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may 1975 old enemies Brazil and Paraguay

have signed an historic pact

construction begins to build the biggest

hydro dam in the world it will harness

the power of the mighty piranha river

the goal an energy bonanza for both

countries the twenty billion dollar

budget is funded by the Brazil

government and by foreign investors

Engineers have found a site on the river

that's perfect for the dam but to build

it they must first divert the piranhas

from the course it is flowed for

thousands of years and reroute it a

massive diversion channel must be carved

through the rock of the riverbank its

job to temporarily divert the river away

from the dam construction site add two

kilometres long and 80 metres deep it

will be the biggest diversion channel

ever attempted but if it fails to divert

the river correctly the whole project is

due

Piero's a Benelli is the engineer in

charge of building the channel it was a

mighty struggle that we fought the

Piranha was the most difficult diversion

ever tried

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second of May 1975 building the entitled

a begins first job to dig the channel

diverting the river

it will take three years of explosives

the chemical diggers and sheer brute

force to slice through the rock

meanwhile others are counting the

environmental cost of such a big dam

once built via taipu dam will turn the

Parana River Valley into a giant

reservoir an area twice the size of

Chicago will be flooded with water to a

depth of a hundred meters as the dig

gets underway environmental consultants

are drafted in their task to assess what

wild animals and plants can be saved

from the coming flood

it's the first dam project to attempt a

major rescue class but at this stage

there are only 17 people involved mostly

volunteers Brazilian fair now Cavanaugh

was one of the team it was the beginning

of the environmental movement all around

the world but regulations weren't as

strict and legal requirements as tough

as they are today it's a race against

the clock if the rescue plan isn't

completed before the valley is flooded

thousands of animals will perish and any

endangered species living here could be

put at risk and the work is time

consuming venture capital spawn toys the

survey basically consisted of walking

through the woods and sighting the

animals looking for their foot tracks

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but people lived here too

some 40,000 of them whole villages and

small farms some of them home to

families for generations will be lost

forever beneath the floodwater they must

be compensated but the authorities need

to know how much to pay out it's one of

the world's biggest ever real estate

valuations and it takes four years to

complete

first the whole area is photographed

from the air to survey homes and

farmland but that doesn't give enough

information to calculate compensation to

get more detailed they must send an army

of photographers on foot to scour every

square metre of the parameter value

these men and women are on a mission

they have to get an accurate valuation

of every home and its surrounding land

everything is recorded and photographed

our better friends values hundreds of

homes medjool south guard houses were

measured described and photographed one

by one would you film and all belongings

even if it was just a stool it was

photograph work while the valuation

process is taking forever but digging of

the diversion channel is right on

schedule

three years after digging began

engineers are all set to demolish the

channels concrete seals and send the

great Parana River pouring down the

channel

8 a.m. on October the 20th 1978 dynamite

charges are set at each end of the

channel it's a tense moment if the

explosion damages the channel it could

set the project back years

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it was a fantastic moment incredible the

blast was like a firework

it's working the mighty piranha is

thundering down its new course it's a

momentous achievement the otaku

engineers have altered the path of one

of South America's biggest rivers but

it's only phase one of the diversion

some water still flows down the old

riverbed next huge temporary dams called

coffer dams must be built to force all

the water down the diversion channel

away from the dam construction site

they're made by dumping huge pieces of

rock into the river until the flow is

stopped the coffer dams might only be

temporary but British engineer Bill beef

knows how secure they have to be

coffered and prevent the river from

flowing into the area where the dam is

being built should these collapse during

construction that would be a total

disaster Brazil has some of the most

torrential rainfall in the world and

rising water could put the copper dams

under pressure or even burst the walls

that would bring a devastating wall of

water down on hundreds of workers

the engineers hoped that they would have

enough warning of rising river levels to

safely evacuate workers until the main

dam walls are built all that stands

between the workers and the threat of

flood is a wall of trouble with the

river piranhas now fully diverted the

biggest job of all building the huge

walls of via type of dam can begin a

hydroelectric dam works by dropping

water on two turbines making them turn

at great speed to create electricity a

taller that dam the greater the drop and

the more power is produced

it type whose engineers know that the

water in the dam must fall a full

hundred meters to produce the promised

record-breaking amounts of power but the

riverbed is only 50 meters deep their

solution build a series of secondary

dams these will raise the height of the

main concrete central dam and make it

tall enough to do the job it means

running the dam structure right across

the valley for seven kilometres awesome

1975 work starts on the secondary down

meanwhile the valuation of the houses

farmed and land in the river valley

which the dam will flood is completed

Brazilian and Paraguayan authorities

learn that before they can submerge the

area they must buy up eight and a half

thousand homes and farms the cost half a

billion dollars in today's money that's

on top of the twenty billion dollars

that dam itself will cost to build

offers of compensation are rushed out

most are accepted but a handful of

people mount legal challenges

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but engineers are more worried about

keeping the secondary dams on schedule

they desperately need more workers an

army of them yet the Piranha Valley is

sparsely populated and remote it's only

town Foz do Iguassu is a small frontier

settlement the nearest big city Sao

Paulo is a thousand kilometers away

project managers must choreograph a

massive migration of workers into the

area they bus in tens of thousands of

workers from all over Brazil

everything a large town needs from

schools and hospitals to churches and

kindergartens has to be built new

housing estates are built just for dam

workers massive catering production

lines are set up to see the

ever-increasing number of workers the

town of Foz do Iguassu is growing at an

incredible rate we're really talking

about moving into a one-horse town with

something like 30,000 workers

what was once a tiny backwater becomes a

gold rush town practically overnight

while the new workers set to work on the

secondary dams the engineers are

wrestling with the design for the vast

main dam that will block the river at

its deepest point all dams must be

capable of one thing they must resist

the unimaginably vast pressure of the

water in the reservoir behind them where

geography allows dams can be simple

walls anchored to the surrounding rock

but it's hypu has no such help from the

terrain it must stand alone so it title

must follow a design that relies solely

on its own weight Engineers call if the

gravity dam the idea is to make the

structure so heavy the water simply

can't move it the work the dam will have

to weigh 61 million tons but the dam is

only as good as its foundation the

bedrock must be incredibly strong any

weaknesses could cause the dam to

collapse and unthinkable disaster

the engineers have undertaken a detailed

survey the results are good the dams

foundations are sound and the engineers

have a money-saving trick of their

sleeve a Dan made out of solid concrete

would weigh more than it needs to and

add huge unnecessary costs they plan to

make the main down walls hollow as long

as it has enough weight it will resist

the water pressures that does not mean

that it has to be absolutely solid it

can be hollow and still with the water

pressure making the dam hollow means its

base can be made even wider with the

same amount of concrete and the walls

will slope more gently pushing the water

pressure down to the base where the dam

is strongest it also means the power

generating equipment can be housed

inside the dam itself it's a clever

solution

June 1979 preparation for the main dam

is well underway and the managers are

determined to stay on schedule

everything is going smoothly but then

the work comes to an abrupt standstill

there's a problem with the bedrock the

people that dug into the foundations we

discovered in fact that the count

divisions weren't exactly at what we had

expected it's disastrous Meuse the

survey gave the bedrock a clean bill of

health

but now engineers have come across a

weak layer of crumbling rock like a

rotten tooth 20 meters down the

engineers fear that it won't support the

weight of the dam if they carry on

building the dam will collapse tunnels

are dug down through the rock so that

engineers can investigate the suspect

layer only a thorough underground

inspection will reveal the scale of the

problem they pray it's just one bad

pocket of rock engineer Corrado PSN team

probes the secrets of the bedrock this

is the good Rock and this is the joint

and weak Rock as you can see it's very

soft not good for the foundation

the crumbling rock stretches right

through the dams planned foundations

building an 11 million ton dam on top of

this would be criminally irresponsible

engineers need to come up with a

solution and fast workers stand idle

while engineers and geologists wrestle

with the problem

finally a hatch a plan that might just

work they can't build on the crumbling

rock layer but can they replace it like

demonic dentists the engineers drill out

the decaying rock and give it a massive

filling with extra strong concrete it's

doing the trick but the extra work will

take months and add 20 million dollars

to the budget

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fixing the crumbling rock layer could

put the whole damn building schedule in

jeopardy

and the relentless heat of the Brazilian

Sun is about to give the engineers

another headache

May 1982 the 40,000 workers building the

Atty poo dam in the heart of South

America have been grappling with a

potentially catastrophic problem

fractured bedrock beneath the

foundations could cause the massively

heavy structure to collapse at stake the

supply of energy to Brazil's future

generations engineers have come up with

a solution and it seems to be working

like a bad tooth the rotten Rock layer

beneath the Atty poop dam site is being

drilled and filled with extra strong

concrete so that it will take the weight

of the dam at the same time work on the

dams giant central walls continues

workers must construct 18 concrete

blocks each four times as high as New

York Statue of Liberty every block will

be cast separately huge steel structures

are erected to receive the concrete and

hold it in place to live set but it's

not just the scale of the job that sets

the engineers a major challenge if they

pour this amount of concrete the usual

way it just won't set properly when

concrete set the cement reacts with

water creating heat in smaller concrete

blocks the core temperature cools and

sets relatively quickly but in massive

blocks of concrete the core temperature

stays high longer and as the surface

cools and sets at a faster rate than the

core hundreds of cracks can appear

fatally weakening the concrete

and that's not the only problem

temperatures here can easily saw past 40

degrees centigrade if the huge blocks

were allowed to set in the Sun they

could reach more than 90 degrees this

too would cause weak spots and cracks

Engineers conduct test after test on

concrete set in these conditions to see

how it reacts to extreme pressure even

good concrete has a breaking point

concrete drive by the Sun will be much

weaker a solution must be found

the engineers have been wrestling with

the concrete problem their answer

refrigeration

on a vast scale

two huge cooling plants will chill every

gram of concrete engineer are Alberto

Janu recalls the scene yet Allah Allah

well our stone was washed with icy water

and blasted with cold air using a large

number of ice chips we were able to

produce concrete with a mean temperature

of just four degrees and because we had

an efficient transportation system the

concrete only reached seven degrees by

the time we were pouring it into the

molds we are in a rocket the scale of

the refrigeration job is vast the two

fonts have the cooling capacity of over

50,000 domestic freezers

by June 1982 the race is on to stay on

schedule for the dams completion in just

three months time seven vast overhead

cableways now feed the dams insatiable

hunger for concrete from six huge

production plants this the mantle is

being trucked in over a thousands of

kilometres at one time something like

about 140 ton truck every 20 minutes was

coming in with cement 40,000 people are

working at a pace equivalent to raising

a 20-story building every 55 minutes as

the project near zero hour

the pace is increasingly serious

Adalberto chinnu ran the work schedule

in order off our key and during

construction we had really tight

deadlines we worked in two shifts of 12

hours for almost 360 days a year yes for

I mean

as the countdown to the dams completion

and the valley flooding begins

conservationists begin their evacuation

of wildlife they hope to save thirty

thousand animals relocating them to new

areas or to wildlife sanctuary

the rescue team knows that it's a race

against time to save as many animals as

possible before the flood

at the same time the massive task of

relocating over eight and a half

thousand families is underway

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compensation claims have been settled in

lengthy negotiations and court cases

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some have been given money others will

be given a similar property and land

elsewhere

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some of these families have lived and

farmed in the Parana valley for

generations

for many it's a devastating moment as

they leave their homes forever the seven

kilometer string of dams is finally

complete

it's haiku takes its place as one of the

longest and most impressive dam

structures in the world but the next

step is absolutely critical

Engineers will now close off the channel

that diverts the Piranha River the river

will then slowly flood the entire valley

creating the vast reservoir that will

feed the dam and drive its power

generating turbines

once filled the water pressure in the

Atty poop dams reservoir will be like

four thousand bulldozers pushing

ceaselessly against the dam walls

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the engineers have done highly detailed

calculations and they're confident that

the massive walls are more than strong

enough to hold back the water but the

filling of any damn reservoir is a

critical moment the concrete of the dam

walls will be all that stands between

the vast reservoir and 280,000 people

living in and around Forster aggressive

the failure of any major dam is always a

major disaster because the amounts of

water that would be freed would create a

wave that would flow down the river and

create tremendous damage

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if the walls of a typhoon would have

failed the escaping wave of water would

dwarf all but the most extreme flash

floods Brazil has ever seen a city sized

body of water would charge down the

piranhas Valley the wave could reach 50

kilometres an hour and demolish all in

its path but the most substantial

buildings

the death toll would depend on whether

people living in the valley had any

warning of the impending flood

June the 3rd 1976 the Teton dam in Idaho

USA is being filmed for the first time

engineers spot a crack in the walls and

try to repair it they sail

two days later the Western third of the

dance simply disintegrates erosion at

the base of the earth and rock Dan is

blamed

nobody had warned local residents the

Teton dam burst causes hundreds of

millions of dollars in damage to

property livestock and crops but

miraculously only 14 people are killed

[Music]

October 1982 seven years since

construction began it's the big day the

massive sluice gates in the diversion

channel are closed the river Parana

flows once again down its original

course it pours over the copper dams it

charges into the reservoir

whatever happens there is no way to stop

the water now and the water rises more

and more pressure is put on the huge

concrete walls

the reservoir will take 14 days to fill

to its final depth of 100 meters

everyone has been evacuated from the

flood area but some stay to watch their

homes disappear under the rising water

and an army of 316 conservationists from

Brazil and Paraguay set out on one last

mission to save as many animals as

possible from drowning

as the water level slowly rise small

islands of high land are left behind

their only temporary and in a few hours

they'll disappear forever beneath the

surface so now they provide a last

desperate refuge for terrified animals

like modern-day Noah's in tiny arks so

now Cavanaugh and his rescue team try to

save as many as they can before it's too

late we do some labs we use some hooks

for the snakes and some we just caught

him by dark by the tails

soon the animals have only treetops to

cling to above the rising water and

there are hazards for the rescue team -

the water was high so you can imagine

itself going by boat on a treetop you

didn't really know what to expect to

find between the leaves sometimes you

just look to your right in about 20 30

centimeters you have a rattlesnake or or

some other kind of poisonous animal but

apart from the odd scratch and bite the

rescuers managed to avoid serious injury

for days the rescue progresses as the

flood waters continue to rise within two

weeks a vast stretch of the piranha

Valley is lost forever it type ooze

reservoir now stretches as far as the

eye can see the dams giant walls are

holding back the water but now the

engineers must stop it riding any

further if the water flows over the top

of the dam the walls could be weakened

and even start to crack with potentially

catastrophic consequences Engineers have

a trick up their sleeve

a crucial escape chute called a spillway

has been built at the edge of the dam

it's like a giant version of the

overflow of your bathtub when the water

gets too high it drains away without

causing a flood the big difference is

this overflow must cope with 64 million

litres of water per second if it's been

wrongly designed the force of the water

could damage it setting the project back

years but there can be no rehearsals the

first time the spillway is used will be

for real October 1982 excited crowds and

world media gather to watch the big

event Engineers prepare to lift the

sluice gates and open the spillway for

the first time the water begins as a

trickle

it soon becomes a raging torrent

it's working the spillway is taking the

strain it's controlling a cascade of

water 22 bigger than Niagara Falls

Brazil is now home to the biggest

man-made waterfall on the planet

engineer Adalberto show new witnesses

the moment prolific develop whelming it

was a really unforgettable spectacle

prism and it will remain engraved on my

memory forever the engineers are

relieved and elated for now but their

spillway worries aren't over yet

the spillway is handling the volume of

water but they know that all that water

thundering off the end could affect the

dam itself

at the Faunus lab in Rio de Janeiro

Roberto de Souza builds detailed

high-tech models of dams to analyze the

consequences of even the smallest

miscalculation in spillway design this

along with Villalobos lives died with

this scale model a dam spillway we're

carrying out an extremely detailed study

of the effects of the water as it falls

of the energy that it can produce an

energy that may damage the structure

yourself when water crashes off the end

of the spillway it lands below the dam

with great force churning up the river

this energy must be dissipated using an

upward curve like a ski jump that forces

the water up into the air reducing its

force if it is 500 hours a year the

energy dissipation is so important that

you could say a good design of spillway

can avoid damage to both the actual

structure and the land downstream

version engineers relied on scale models

to get the angle of the ski jump just

right if it's wrong the water will turn

back on itself and could seriously erode

the riverbanks and if the process

continued over years it could eat away

at the foundations of the dam

it titles engineers have calculated that

there will be some erosion but not

enough to do any serious damage all they

can do for now is keep checking the

riverbanks and soup

if they've got it wrong the structure of

the dam itself could be in peril

[Music]

the vast reservoir feeding via type of

dam has been filled flooding thousands

of square kilometers of agricultural

land and rainforest 30 thousands

assorted birds mammals and reptiles are

saved from drowning by conservationists

but they all need new homes some are

relocated but three-hundred rescued

animals are found a new home in a

wildlife sanctuary the Bella Vista

refuge isn't a zoo the endangered

species that were saved will be bred

here and ultimately returned to the wild

Bella Vista is also one of the first

centers aimed at educating local people

about the wildlife living around them

700 square kilometers of forest are lost

in the valley flooding but millions of

new sapling czar planted around the

reservoirs edge conservation program

like the one mounted at e-type ooh looks

basic by modern standards

but in the 80s it represents a

trailblazing bid to minimize the damage

caused by large-scale dams over the next

nine years a type whose final frenetic

stage unfolds with the dam walls

finished work begins on the power

generating plant 18 giant tubes to

funnel water to the turbines each as

tall as a 30-story building go up the

turbines themselves weigh 800 tons as

much as two jumbo jets

they're so huge that special vehicles

have to be built to transport them

at the heart of each turbine Lizer rotor

they will spin magnets within a copper

coil to produce electricity

although the rotors are more than 16

meters across

they must be precisely installed to

within 1/10 of a millimeter and that's

not all

the bulk of it Thai food dams

electricity is destined for the huge

cities of Sao Paulo and Rio de Janeiro

but they're over a thousand kilometres

away a massive network of pylons

stretching right across the Brazilian

countryside is erected the electric

power lines from the dam are long enough

to stretch around the globe

one and a half times as the dam nears

the moment when it will produce power

engineers nervously inspect the

riverbanks for signs of damage from

water thundering down from the spillway

this is the kind of erosion that huge

volumes of water can do when traveling

at high speed how serious is the erosion

caused by the spillway

it doesn't have good the engineers take

precise measurements they make further

calculations

is the erosion creeping ever closer to

the dams foundations

to their great relief the engineers find

their original predictions are right the

erosion is not getting any worse the

foundations of the dam are safe its high

pool nears completion the pace has been

unrelenting

but the biggest engineering project

South America has ever seen comes at

great human cost

records aren't precise but a hundred and

forty-five people are thought to have

lost their lives in accidents while

building in taipu

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May 1984 and e-type who is about to

fulfill its purpose and produce its

first electricity it's the moment

everyone has been waiting for the

culmination of nine years of grueling

work water pours in through the gates at

the top of the dam thunders down and

turns the turbines for the engineers and

workers it's a triumph one by one

further turbines leap to life and in

April 1991 a Titan becomes the most

powerful hydroelectric plant on the

planet pumping out enough electricity to

light up a hundred and twenty million

light bulbs and a typo is now feeding

the energy demands of 24 million

Brazilians in Rio de Janeiro and Sao

Paulo

the electricity flows without a hitch

for 10 years

until January the 21st 2002 1:30 p.m.

without any warning 13 of their type

who's 18 giant turbines suddenly grind

to a halt electricity production stops

the engineers at it title are mystified

what has gone wrong Rio and Sao Paulo

are forced to a standstill traffic

lights stopped working causing 30 mild

backups subway systems closed down

people are trapped in elevators offices

homes factories are plunged into

darkness what is causing this

cataclysmic power failure

josé ricardo de Silveira was in charge

of power output port set up all the

generators and all the transmission my

systems to Brazil suddenly cut out at

the time we didn't know exactly what was

going on

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after forensic investigations

electricians finally track the problem

down apparently has collapsed the

transmission system can't cope with the

power level that it type who is

generating spits twist the switch that

turns off the mighty dams generating

systems there's an inquiry it's the

result 12 billion dollars are poured

into upgrading the transmission system

to prevent future blackouts in just one

afternoon Brazil cities have seen just

how dependent they are on a type whose

electricity

[Music]

20 years on the Atty ku'Damm remains an

extraordinary achievement and was

recently voted one of the seven wonders

of the modern world by engineers today a

staggering 90 percent of Brazil's energy

is generated by hydroelectric dams stand

like this have helped Brazilian cities

and industries to grow and brought

electricity to people in remote areas of

the country but the heavy reliance on

water power has come at a price in

recent years lower rainfall levels have

reduced the power output from dams

forcing power cuts and energy rationing

and all around the world there's a

growing awareness of the environmental

havoc that hydroelectric dams can cause

at it type ooh dead treetops serve as a

powerful reminder of a valley that has

gone forever and the enormous price

Brazilians have paid in their quest for

power

[Music]

you