Original subtitles

[narrator] Water is the source of all life on our planet.

Over thousands of years, humans sought ingenious ways

to control and store it, with one method above all else

representing a towering symbol of that ingenuity...

the dam.

[Dr. Shini] More than just a vast wall

of steel and concrete, the dam is an essential tool

in human survival.

But dams can be deadly.

Brazil, 2019.

Millions of tons of toxic sludge were unleashed,

when the walls of a dam gave way.

The result was a devastating environmental disaster

that claimed the lives of 270 workers

and anyone unfortunate enough to be in its path.

[Daniel] If you're underneath the dam,

it looks like the entire surface of the earth

has detached and is now rushing towards you.

[thunder crashing]

In September 2023,

an estimated 24,000 people lost their lives in the Libyan city

of Derna, when not one, but two dams collapsed.

[Dr. Shini] A 30-foot-high wall of water

slams into the city below.

In 1959, 423 people on France's southern coast died

when a newly built dam collapsed,

flattening villages and a town.

[Rob] Nobody knew at the time,

but the location was right across a geological fault line.

With an estimated 60,000 large dams in operation worldwide,

have engineers truly learned the lessons of the past?

[indistinct chatter]

Or is the clock quietly ticking down to the next example

of fatal engineering?

[theme music playing]

[menacing tones playing]

We are on the French Riviera.

A unique coastline boasts the clear blue waters

of the Mediterranean and rugged hills,

known for their raw, untamed beauty.

But since 1959, the region has carried a permanent scar,

a name that still haunts its people to this day --

Malpasset.

The circumstances over a number of years

have all conspired to this one moment in time.

[water rumbling]

It's 9:13 PM, on Wednesday, December 2, 1959,

when the unthinkable happens.

The Malpasset Dam, holding back

50 billion cubic meters of water,

the equivalent of 20 million Olympic swimming pools,

collapses without warning.

[water roars]

The entire dam unpeels from right to left,

unleashing all of the water,

dumps it straight into the valley.

[water roaring]

The rupture unleashes a 40-meter-high wave,

the height of a 13-story building.

600-tons sections of the dam's walls are hurled

hundreds of meters away like pebbles,

obliterating everything in their path.

[powerful music playing]

At an estimated speed of 43 miles per hour,

the water charges downriver, almost instantly destroying

the two small villages.

[Daniel] The water then barrels further down the valley

towards the town of Fréjus.

[menacing music playing]

9:33 PM.

Just 20 minutes after the collapse, the wall of water

reaches the town of Fréjus, home to 13,000 people.

Still three meters tall, the water is now littered

with debris and concrete, making it all the more deadly.

This relentless force floods the western part of the city,

taking only five minutes to wash away

30 kilometers of railway tracks.

[menacing music continues]

10:00 PM.

Nearly 45 minutes after the disaster begins,

the raging torrent finally reaches the Mediterranean Sea.

The next morning, survivors awaken to horror.

[Dr. Shini] But most tragically,

approximately 423 people lost their lives,

although the true figure could have been much higher.

Why did a dam built of concrete and steel fail so suddenly?

We are in the late 1940s in Southern France,

in the city of Fréjus.

Regular droughts during the long, hot summers

severely impact this growing city,

and local farmworkers struggle to make a living

from the arid land.

[Dr. Shini] What they all needed was a regulated flow of water,

a steady and reliable supply for agriculture,

domestic use, and as a center for booming tourism.

[Rob] It was decided that a dam should be built to control

the rainfall and control the flow of water.

[Daniel] And so surveys were done looking for the best place

to put a large dam to control these seasonal flooding events

that would happen.

Experts identify a narrow gorge in the Reyran Valley,

located 12 kilometers upstream from Fréjus.

It's the work of French engineer André Coyne.

With 70 dams to his name, his work was widely respected.

Standing 66 meters high, the equivalent

of a 22-story building, and 222 meters long,

the Malpasset Dam is made of concrete and steel.

With a solid masonry foundation,

it measures 6.78 meters wide at the base

and 1.5 meters thick at the top.

[Daniel] He chose a double arch dam.

And this dam is very unique and very well suited

because it minimizes the material

while maximizing its strength.

Built to hold 50 billion cubic meters of water

stored in the reservoir behind it,

the upstream facing curved design

distributes the immense weight of the water

along the structure and onto the opposing banks.

Control valves at the base of the wall

and a spillway at its center

are designed to release water and prevent

excessive pressure buildup on the dam.

For centuries, arch dams have been a proven

and tested design,

but they must be built in the right location.

[Daniel The selection was more based on the size

and shape of the valley,

and not so much about the underlying geology.

Nobody knew at the time, but the location

where the Malpasset Dam was built

was right across a geological fault line.

Where you have a fault line, you have bedrock that moves,

maybe moves imperceivably to the human eye,

but it moves all the same.

And if you build something on top of that rock,

if your foundations move, your structure will also move,

and movement is not a word that you associate with a dam wall.

In their rush to construct it,

André Coyne and his team of engineers

failed to fully assess the risks

posed by the terrain beneath the dam.

This oversight doomed the Malpasset Dam

from the moment of its construction

and would set off a catastrophic chain of events

for the valley's residents below.

The decision to ignore it

would be the first fatal mistake.

Celebrated as a marvel of construction

at its inauguration in 1954,

the Malpasset Dam was destined for failure.

But is this engineering error the only factor responsible

for the terrible disaster?

[Daniel] Usually, when you construct a dam,

proper procedure to test its mechanical robustness

is to fill a little bit, drain, look for leaks,

fill a little bit more, this incremental

and repeated filling.

[Rob] And you can let it do its job for decades to come.

That didn't happen at Malpasset.

The Reyran River, which feeds the Malpasset Dam,

is dry for nine months of the year,

limiting the ability to fill the reservoir incrementally

and test the dam.

And so, in this case, it was never really tested

until it was at its full capacity,

and the problems that existed

weren't known until it was completely full.

It takes five years for the reservoir

to reach full capacity, but during this time,

as the dam slowly fills, water begins seeping

into the geological fault beneath the structure.

The pressure exerted by the reservoir increases

as the water level rises,

forcing water deeper into the fault.

[water babbles]

[Rob] The pressure where that water was entering the bedrock cracks

pushing the water ever further,

splitting the rocks ever more. It's a chain reaction.

In November 1959, one month before the collapse,

with the water level still seven meters below the top,

small cracks begin to appear on the dam's wall.

Considered minor leaks, they are ignored by engineers,

convinced that the design is strong enough

to withstand these anomalies.

But there's more...

[water roaring]

[thunder crashing]

A new factor further accelerates the tragic fate

of the Malpasset Dam.

[thunder crashing]

There is a huge storm that is dumping

a tremendous amount of water down onto the earth.

[rain hissing]

The reservoir fills rapidly.

The dam's caretaker requests permission

to open a control valve at the base of the wall

to release water and reduce pressure

from the rising levels.

-[water gushing] -[thunder crashing]

[menacing music playing]

His request is denied.

Because just downstream,

there's a huge highway construction project,

this massive A8 highway that will connect

the regions of Southern France.

And the concern is this uncontrolled release of water

will obliterate the construction site.

[thunder crashing]

5:30 PM.

For the first time, the dam reaches maximum capacity.

It now has to withstand the pressure

of 50 million cubic meters of water,

enough to fill 20,000 Olympic swimming pools.

[rain hissing loudly]

As the heavy rain continues to pour, the dam's engineer,

André Coyne, arrives on site to inspect his structure.

Aware of the risks threatening the dam,

he finally orders the control valves to be opened.

It's 6:00 PM

He doesn't know it yet, but it's already too late.

The damage has been done.

[Dr. Shini] Downstream, thousands of residents from several

small villages and those in the town of Fréjus

are blissfully unaware that a now unstoppable

chain of events has begun

that would ultimately destroy their world.

9:00 PM.

Despite warnings that the dam was in danger of bursting,

the local authorities had not issued any orders to evacuate

the town and surrounding area.

One final and disastrous factor would then come into play...

[intense music builds]

The A8 motorway construction, just a kilometer downstream

from the dam, a project that had been underway for months.

[Dr. Shini] While on site, engineers are aware of the dam,

but confident their construction works would do nothing

to affect the stability of the dam wall.

However, one crucial and fatal decision changed everything --

the use of dynamite.

[explosion blasting]

Blasting is a common construction technique

used to break up extremely hard mountain rock.

However, the detonations create shock waves

that reverberate through the ground.

That blasting

is only gonna exacerbate

whatever existing problems happen.

Each blast sends violent shockwaves

towards the fault line.

[Dr. Shini] What had been small but acceptable cracks

in the immense wall has now turned into large streams

of water running down the right side of the structure.

With the unstable bedrock, the increasing amount

of pressure on the water making its way into the cracks,

and the explosions occurring just a kilometer away...

[explosion blasts]

...all the pieces of this disastrous jigsaw

are now in place.

9:13 PM.

The dam, once a symbol of modern engineering,

collapses under the pressure.

[rumbling]

The collapse begins with the right-hand side

failing first, spreading quickly from right to left.

And as you're looking up at the giant wall,

huge chunks of steel-reinforced concrete break away

from the dam, releasing a 40-meter-high wall of water

down into the valley.

The raging water destroys everything in its path

at an estimated speed of 70 kilometers per hour.

[melancholic music playing]

A five-kilometer stretch of the Reyran Valley

is literally wiped out.

The town of Fréjus is pummeled.

155 buildings are completely destroyed and 796 are damaged.

But the most tragic loss was the human toll.

Although the actual number may be higher,

423 people perish when the Malpasset Dam bursts.

[Daniel] The lessons that can be learned

are that it pays

to do your homework at the beginning, right?

The dam selection criteria -- where is it

and what is the underlying geology is most important,

because if you get that wrong, it doesn't matter

how fancy your dam is,

you are building it on shaky ground.

A poor site selection and bad construction practices

were enough to doom the structure from the start,

making the Malpasset Dam collapse

the worst dam disaster in France.

But what happens when dams that are not made

of steel and concrete collapse?

[enigmatic music playing]

11th of September, 2023, the day when the city of Derna,

on the Mediterranean coast of Libya,

is put on the map...

but for all the wrong reasons.

[thunder crashing]

It's 1:00 AM.

13 kilometers away, the Al-Bilad Dam has burst,

sending a terrifying wall of water

towards the country's 18th most populous city.

All that remains between their safety and the total

disaster heading their way is a second larger dam.

Located on the outskirts of the city,

the Abu Mansour Dam is much larger than the first.

It serves as a shield for Derna's 100,000 inhabitants

in the event of flooding,

and is intended to be able to contain the hellish flood

heading their way.

Tragically, the pressure is too great.

The entirety of Derna is asleep, and so they are unaware

of this catastrophe which is about to happen.

[water gushing]

This second dam offers little resistance to the gigantic,

overpowering wave. It's now 3:00 AM.

[Dr. Shini] In a deafening roar, the dam collapses.

[Daniel] All of that water is now released into Derna,

Buildings are no match for the destructive power

of water and mud.

[transformer blowing]

The power goes out, plunging the city into darkness.

Residents scramble to safety on rooftops.

[menacing music continues]

As day breaks the following morning,

the true extent of the devastation can be seen.

The city looks like a war zone.

[rescuer yells indistinctly]

[speaking in Arabic]

Although the official death toll is 5,923,

this fatal wall of water was estimated to have actually

claimed the lives of 24,000 people,

a quarter of the city's population.

It was the second deadliest dam burst in history.

What meteorological and technological phenomena

turned these monumental civil engineering structures

into fatal engineering?

[tape whirring backwards]

[menacing music playing]

[Rob] That region had experienced

violent Mediterranean storms in the past --

in the forties, the fifties, and in the sixties.

They weren't protected from the environment,

and so it necessitated, at the time,

some amount of water control.

It was decided that a dam was the right piece

of infrastructure to protect the city of Derna,

but not just one dam, a series of two dams.

Built in the 1970s, by a then Yugoslavian company,

the first dam is located upstream of the Derna River,

Its reservoir can hold 1.5 million cubic meters,

equivalent to the volume of 600 Olympic-sized swimming pools.

[Rob] The Al-Bilad Dam would be a smaller structure to contain

rainwater and slow any flow coming through the valley

towards the city.

[Daniel] It would augment the ability of the first dam,

the main dam, to control the floodwaters.

The Abu Mansour Dam is located on the outskirts of the city,

just a few hundred meters from its edges.

At 75 meters high, it can hold 22.5 million cubic meters,

15 times more than the Al-Bilad Dam.

The second dam, the Abu Mansour Dam,

would be much bigger, as almost a backstop

to the first dam -- working together...

the city of Derna would be protected

from even the worst storm...

or so it was thought.

[thunder crashing]

Here, in Libya, it was decided

that an embankment dam would be built.

Low-cost and easy to construct in this arid area,

an embankment dam uses a gravity-based design

that relies on its own mass to hold back water.

The Al-Bilad and Abu Mansour dams consist of two main parts,

a central core constructed of large blocks of concrete

and rocks, which is then filled with clay to reinforce it,

creating an impermeable wall.

It's covered with an outer layer

of more natural materials, such as earth,

sand, and pebbles, which can be sourced locally.

Since it is just natural material,

the environment eats away at it more easily than

a more rub and bust material like concrete.

It's not sophisticated. It's just dirt, right?

And so the effect of water on that can be catastrophic

if it's not done well.

When the Al-Bilad Dam was built,

it seemed to be an appropriate choice

for the volume of water needed to be held

to safely control the seasonal floods that, in the past,

had caused so much damage to the city of Derna.

[thunder crashing]

[Dr. Shini] This was back in 1970.

What the engineers couldn't have predicted back then,

and therefore hadn't taken into account, would be

the devastating and unstoppable effects of climate change.

At the beginning of September 2023,

Storm Daniel wreaked havoc in the Mediterranean Sea.

It caused more than two billion US dollars

in damages in Greece and Turkey

before moving toward the North African coast.

[thunder crashing]

On the morning of September 10, rain, estimated at 250 times

the average monthly amount, fell in just 24 hours.

The authorities declared a state of emergency

as unprecedented rainfall poured more and more water

into the Derna Valley upstream of the city.

What was normally a dry riverbed,

now resembled a surging flood.

[Daniel] The only thing in between Derna

and that massive amount of water are the dams, damming the river.

It's 12:30 AM and Storm Daniel has been raging,

as unprecedented rainfall poured more and more water

into the Derna Valley upstream of the city.

The water rushes into the reservoir of the Al-Bilad Dam.

Like all dams, it is equipped with safety mechanisms called

spillways that are designed to release excess water.

The spillway is built lower than the desired maximum level

of the reservoir.

When the water reaches its level,

it begins to overflow into the spillway,

allowing the water to be diverted in a controlled manner

to the other side of the dam, preventing the water level

from rising dangerously.

But in this case, there's just so much water

that the spillways can't take up that volume.

It's 12:55 AM.

The reservoir level quickly reaches its maximum capacity.

At this point, a devastating phenomenon occurs

that will trigger the carnage to come.

There's a mechanism which is called overtopping,

which is extremely bad for dams, in earthen dams in particular.

Overtopping is when the water that exceeds the dam walls

begins to cascade over the opposite side of the wall.

[Daniel] The water that's overtopping the dam

isn't going very quickly,

but it's falling a long distance.

And so, with that distance, there's a lot of kinetic energy

that's being imparted into the dam, this earthen dam --

it's not gonna stand up to that abuse,

and so it just erodes.

When the overtopping of an embankment dam

like Al-Bilad begins, the loose materials,

especially earth and clay components,

are quickly washed away.

And if the structure is old and not properly maintained,

the effect is compounded.

Such is the case with the Al-Bilad Dam.

It's 1:00 AM.

The pressure is too much, and the Al-Bilad Dam completely

completely gives way to the unstoppable force behind it.

-[concrete crashing] -[water roaring]

The only thing standing in between Derna and the huge

amount of water that's been released barreling down

the valley is the Abu Mansour Dam.

[Rob] That wall of water crashes into the reservoir.

-[water running] -[dramatic music playing]

And that reservoir level rises very, very quickly.

Built to withstand a load

at least five times greater than that of the Al-Bilad Dam,

the designers hoped that the Abu Mansour Dam

would be able to absorb the additional load

imposed on it and protect the city below.

However, within 30 minutes, the levels quickly surpass

the height of the wall, and, as with the Al-Bilad Dam,

the water begins to overflow, crashing against the base

on the other side, but that's not all.

A history of poor maintenance leads to another devastating

factor that transforms this final barrier to the city

into a massively destructive force.

[dramatic music playing]

The Abu Mansour Dam had already been crumbling

for several years, with cracks forming on its surface.

When this raging wave strikes the wall

during that dreadful night, it seeps into these cracks,

creating what engineers call -- piping.

If you allow water to pass through even the smallest gaps

within your wall, those gaps can start to open up and grow

over time until your wall is weakened.

[dramatic music playing]

[Rob] That water makes the dam wall unstable until,

at a point, the wall is no longer strong enough

to hold back that weight of water.

3:00 AM.

Weakened and under pressure from all sides,

the Abu Mansour Dam completely gives way.

[Dr. Shini] A 30-foot-high wall of water

slams into the city below,

obliterating entire neighborhoods in just seconds.

[dramatic music playing]

The lucky ones are those who perish fast asleep,

no idea what's happened.

The unlucky ones are those who actually experience

the terrifying view, the terrifying sound

of this mass of water crashing towards you,

knowing that there is nowhere to escape.

Due to these fatal engineering errors, an estimated

24,000 people have died, and thousands more

are left homeless, having lost everything.

A humanitarian disaster that serves as a reminder

of the importance of maintaining dams

if we want them to continue to protect us

rather than destroy us.

[somber music continues]

Examples of fatal engineering can be the result

of mistakes in construction.

They can be the result of mistakes in design

and calculations of materials and dimensions, or they can be

the result of mismanagement and lack of maintenance.

So what happens when all three are at play?

[enigmatic music playing]

With its 21 million inhabitants, or ten percent

of the Brazilian population, the state of Minas Gerais

is one of the richest and most dynamic in the country.

Known for mining activities, a wealth of minerals such as

gold and diamonds, it alone accounts

for almost 10% of Brazil's GDP.

The Córrego do Feijão iron mine

in the municipality of Brumadinho

is one of the beating hearts of the local economy.

[Rob] It is the biggest employer.

Families who live together in the town

work together in the mine.

[Daniel] This mine has been in existence for decades.

And one of the things that happens in iron ore mining is

there's a lot of waste generated.

This is called tailings.

[Rob] And at the Brumadinho mine,

similarly to many iron ore mines, it was stored nearby

and contained with what's called a tailings dam.

At 86 meters high, the height of a 30-story building,

Brumadinho Dam B1 contains 12 million cubic meters

of iron ore tailings, enough to fill 480

Olympic-sized swimming pools with a highly toxic liquid.

But on this day, January 25, 2019,

it's about to trigger the most devastating event

the region has ever seen.

12:27 PM, Brumadinho dam.

[Daniel] The workers are taking a break, eating lunch.

The dam is in the distance, and then there is a deep rumble.

It's 12:28 PM, when the mine surveillance cameras capture

these frightening images

straight out of a Hollywood movie.

[earth rumbling]

[Daniel] If you're underneath the dam,

it looks like the entire surface of the earth has detached

and is now rushing towards you.

[Daniel] It is impossible to survive an encounter

with this type of material,

a toxic mixture of mud and water.

And while -- not be moving very fast,

it will consume whatever in its path.

Buildings, bridges, roads, and railroads are engulfed

by the merciless 70-kilometer-per-hour wave

of mud that devours everything in its path.

[dramatic music playing]

[rumbling]

In all, the disaster led to the death of 270 people.

[mournful music playing]

A humanitarian and ecological disaster.

[Dr. Shini] Riverbanks turn orange,

fish stocks are wiped out due to a lack of oxygen,

and irrigation water, needed for agriculture,

is rendered deadly.

[helicopter engine whirring]

This tsunami of toxic mud contaminated 700 kilometers

of river and affected the lives of 250,000 people.

It is the most devastating mining disaster

in Brazil's history.

[Dr. Shini] What was the trigger point that caused

such a catastrophic collapse?

And could it have been prevented?

First, we need to understand

how this unique structure works.

Tailings dams are built like a layer cake.

An initial dike upstream of the mine,

constructed in 1976, serves as the base for what will become

this enormous 86-meter-high structure.

[Rob] You're building a wall,

basically out of your waste material

that's enough to contain the waste behind it.

And you can build on top of it.

[Rob] It's a fairly convenient and cheap means of storing

waste material and keeping it

in a place that's contained.

Or at least, that's the idea.

The tailings are mostly liquid, soft, and toxic.

To solidify the material, it had to be drained.

[Rob] All the waste material that's built up behind

this rather rudimentary embankment wall

is allowed to separate over time so that the solids

fall away from any liquid or water that's left on the top.

That water, then over time, evaporates, and you've got

a solid base, which you can then start

to put more waste on top of and go again.

The drying is important.

And so wet tailings, bad. Dry tailings, good.

Over time, the site forms a large, solid structure

that becomes part of the landscape

and is reclaimed by nature.

But this method of storage also has its drawbacks.

It's not as structurally sound as building a barrier, a wall,

to contain something behind it out of concrete and steel.

And the waste in the dam can sometimes mix with water,

making it tricky to keep everything dry and safe.

And too much water can weaken the dam.

Water, the enemy of every tailings dam.

[Daniel] One of the most important things

for a tailings dam is to control where the water goes, right?

If the water impregnates the tailings dam,

the mechanical stability of the dam can be compromised.

Although the Brumadinho Dam reached its maximum

operating level in 2016, water was to become the trigger

for the disaster to come.

[rumbling]

Three years later, the dam collapse would

devastate homes, livelihoods, and lives.

The mine owners were aware the problems

the water was creating and tried to find solutions.

The first engineering technique to help remove excess water

from the accumulated tailings involved creating a large,

flat, and dry area behind the dam,

which they called the beach.

[Dr. Shini] As fresh tailings are poured across the beach,

they're spread out like a thin layer of mud,

speeding up the drying process, similar to a puddle of water

drying in the sun.

It also had the effect

to draw out some of the moisture from the waste tailings dam

and dry that out and, in turn, give more stability

to that tailing structure.

Following this, the engineers devised

an additional process to remove water from the dam.

[Dr. Shini] Channels or canals are built into each new layer

as it's created.

Pumps would then move the water away from the site.

Although these methods are normally quite effective

in ensuring the safety of the Brumadinho Dam,

they would not be enough.

[thunder crashing]

[menacing music playing]

By the end of 2018, southeastern Brazil experienced

unusually heavy and prolonged rainfall.

As a result, the pumps struggled

to function, and the drains could not keep up

with the deluge, often becoming clogged.

[Rob] Rather than evaporating, all of that water

was being absorbed by the waste materials,

making it much less structurally sound

and much less capable of holding anything back behind it.

With water and moisture levels in the dam rising faster than

they could be reduced, the engineers came up

with what they believed to be a perfect solution.

They came up with a third solution, and that was to drill

a series of 50-millimeter boreholes through the dam walls

[Dr. Shini] The horizontal drain holes would effectively act

like straws and allow trapped water

behind the trailing walls to escape.

The drains did not allow enough water to escape as needed.

Worse, they weakened the structure.

[Rob] And whilst these horizontal drain holes

did allow some water to drain, they would be the crucial part

of mistakes that were made at a mining dam.

On June 11, 2018, a borehole in the wall of the first dike

at the base of the dam collapsed.

Mud and waste spilled from the dam.

The drainage program was immediately abandoned.

The problem now is the dam has become mechanically compromised

and is on the verge of instability.

[Rob] Employees are working

to backfill the holes with concrete now.

Anything they can think of to bring

structure back into the dam.

Although the Brumadinho Dam appeared solid

from the outside, inside it was compromised

and filled with water.

What seemed like the ideal solution to save the dam

from water infiltration

ultimately weakened the structure

and led it to its collapse

on January 25, 2019.

[Daniel] On the day of the collapse,

even though the mine has been indicating

that it's in a little bit of trouble.

Nothing really indicates that a catastrophe

is about to happen.

[birds chirping]

12:28 PM.

While most workers were having lunch at the site's canteen,

the dam collapses.

-[dramatic music playing] -[rumbling]

[Daniel] The entire structure of the dam

gives way in one large,

sort of, sweeping motion where the front face of the dam

cracks loose and then begins to slide forward.

[Dr. Shini] Within seconds, a 30-meter-high wall

of toxic material races towards the canteen

and surrounding buildings,

wiping out everything in its path.

[debris rumbling]

[epic music playing]

In total, the Brumadinho Dam collapse results in 270 deaths,

with three people still missing.

Their bodies remain buried

under more than seven meters of mud.

[mournful music playing]

[speaking Portuguese]

[speaking Portuguese]

T housands of people who depend on the river

saw their livelihoods instantly destroyed.

[speaking Portuguese]

A tragedy with multiple consequences,

and not the first to hit the region.

Well, not only Brumadinho, but other tailings dam collapses

happening in Brazil.

A similar disaster occurred just four years earlier,

100 kilometers east, in the town of Mariana.

In addition to its mining industry,

the state of Minas Gerais has the largest number of dams

in Brazil, with a total of 3,000 structures

of all types.

Following the Mariana catastrophe, Vale,

the mine's owner, was ordered to pay 7 billion US dollars

for cleanup efforts and compensation

for the victims' families.

Tailings dams can be a practical solution,

but only when they're meticulously managed

and maintained to avoid the kind of environmental

disaster that happened at Brumadinho.

[Daniel] The fatal engineering that exists in this

is the lack of ability of the engineers to maintain

the health of the dam.

This was a structure that is always teetering

on the edge of failure.

For millennia, dams have played a vital role in human life,

allowing us to control one of the most precious resources

on our planet, water.

But history has repeatedly reminded us

that these colossal structures can also destroy life.

[Daniel Nature will always erode and degrade the structure.

Even the pyramids, even though they're thousands of years old,

they show the signs of weathering.

Dams are the same way.

You have to put the time, effort, and energy

into maintaining a structure,

otherwise it will always collapse.

These massive dams must remain marvels of human engineering

and not examples of fatal engineering.