All language subtitles for Building.Giants.S05E09.1080p.WEB.h264-CBFM_track3_[eng]

[narrator]
High in the Colorado Rockies,
an elite team of engineers is

taking on a seemingly
impossible challenge.

This is gonna be
one for the record books

and the resume.

They're racing to build
an extraordinary new mega dam.

We're under a lot of pressure
to get this done on schedule.

The clock is ticking.

A chronic drought puts
the water supply

for millions of people at risk.

If we don't do something now,
we will be too late.

To succeed,
they must safely fuse

70-year-old
construction methods

with cutting-edge engineering.

This mega dam

ranks in a league of ambitious
new engineering wonders that

are bigger, faster,
taller, and more advanced

than anything ever
constructed before.

This is the inside story of
the extraordinary challenge of

building these giants.

Colorado is facing a crisis.

It has long relied on
melting mountain snowpack

for its water supply.

Climate change is reducing
snowfall and shortening

the melt season.

This means more water runs off

before it can be stored
in reservoirs.

Colorado must capture
a greater amount of

the dwindling snowmelt.

If these efforts fail,
reports suggest the state

could run out of water
within 25 years.

To meet this challenge,
engineers in Colorado are now

working on a series of
megastructures to boost

the state's reserves of water.

The Gross Dam was built
in the 1950s

to help supply
the growing population

of Colorado's state
capital, Denver.

Constructed from over
1,400 concrete blocks,

it rose to
an impressive 335 feet

and was designed to hold back

over 13 billion gallons
of water.

But that's not enough to meet
the demand of the 21st century.

The plan today is to
triple its capacity.

Jeff Martin leads the team
tasked with making it happen.

[Jeff] The original Gross Dam is
just an amazing structure.

Just, unfortunately, now,
it doesn't hold

as much water as we need.

So, we're gonna solve
our problem,

by raising the Gross Dam

to create more water
storage behind it.

Engineers must build
a completely new dam on top of

the old one.

To succeed, they must beat
extreme weather,

tough geology,
and a tight deadline

set by the Federal government.

The engineers will build up
the height of the dam

by a third to
a colossal 471 feet.

They will double the length of
the crest of the dam

to 2,040 feet,

and build a brand-new spillway
to release surplus water.

The team will pour over
21 million cubic feet of

special concrete to make
the wall's 118 steps,

and expand the width of
the dam's base to 300 feet.

The new gross dam will be
the tallest dam in Colorado

and hold back a staggering
38 billion gallons of water.

This megaproject transforms
the structure from

a gravity dam into
an arched dam.

This will be the first time in
the world that engineers

have attempted to do this.

Engineer of record,
Felipe Garcia, and his team

have been brought on
to make it happen.

So, the original Gross Dam was
designed as

a curved gravity structure.

What I mean by a curved gravity
dam is that it has enough

weight to maintain stability

against the pressure
of the reservoir.

But relying on their sheer
mass to hold back a reservoir

makes gravity dams
expensive and inefficient.

A arch dam achieves
its stable factor of safety by

transferring the loads from

the reservoir laterally
towards the abutment.

And in turn, you're able to
make the arch thinner.

Not only that reduces
cost and schedule, but it also

provides a more
sustainable project.

Engineering teams must build
solid foundations on both sides

of the canyon to support

the greater width of
the new dam.

But the geology in this part of
Colorado presents

a big problem.

What we have here

is pretty typical of about
90% of the foundation

of we have
out there at Gross.

It is very strong rock,
but from this particular slope,

this material is
highly weathered.

You see?
I -- I can just peel it

with my hand -- that means
that it doesn't have

enough stiffness to support
the loads from the dam.

So, this material would need to
be removed.

The teams use a fleet of
excavators to scrape away

the loose weathered rock.

Next, the team pours nearly
705,000 cubic feet of concrete

to build a super strong
and perfectly level foundation

that bonds tightly
to the bedrock.

It takes around 20 months

to prepare the canyon walls
for the new dam.

The engineers' next task is to
prepare the concrete of

the old dam to make sure
that it bonds

to the concrete of
the new one.

[Jeff] A concrete dam moves.
It lives.

So, the new dam and old dam
have to hold together.

They have to bond.
They have to move together.

That's critical to
the performance of the dam.

One of the first things we need
to do to build this dam is

roughen up the face of
the old dam

so we can get the new dam
to stick to it.

To create this crucial bond,

a blaster fires water at
a pressure of nearly

20,000 pounds per square inch

to strip away the top layer
of concrete.

A large saw cuts slices into
the crest of the dam.

A hydraulic hammer
then breaks up the concrete

before another water blaster
finishes the job.

These processes leave the dam
with a rough surface to allow

the new concrete to form
a super strong bond.

[Felipe]
The activity that's going on
right now is what we call doing

a hydro demolition
of the downstream face

of the existing dam.

We're removing the outer layers
of the skin of

the existing dam,
but we want to make sure

and be careful not to remove
too much of it

for a large extended area,

because at the end of
the day, right,

we're raising Gross Dam
while it's still in operation.

While the water blaster roughs
up the concrete, a team at

the top of the dam wrestles
with the next challenge.

Here is the crest of
the old dam's spillway,

the structure that allows
the safe release

of excess water.

It's Casey Dick's
responsibility to remove it

before the team raises
the height of the dam.

We couldn't just build right
on top of the existing spillway

as it sits right now,

because the top of it
is rounded.

If we tried to just start
placing concrete right on this

rounded surface,
it would just fall right off

and we'd never be able to
get it started.

Deconstructing this critical
part of the old dam is

a major operation.

The concrete is very heavy by
its nature, so if we cut it off

in one giant piece,
we wouldn't be able to actually

remove it from the dam.

So we have to slice it up
into smaller pieces,

about the size of a vehicle,
so that the cranes can then

hoist it off one piece
at a time.

The team deploys a special
cutting system to get

the job done.

To remove the old spillway,
we have this apparatus that

uses diamond-encrusted rope,
wire rope, so it's really hard

and it's abrasive,
and as you drag that through

the concrete, those crystals
are stronger than the concrete

and it's able to cut right
through the concrete.

So basically, this rope is just
going through the dam,

cutting the concrete like
a cheese cutter.

Over the next two years,
the team blasts,

cuts, and cracks apart
the old dam.

Now the engineers can start
the next phase,

an innovative concrete pouring
process to ensure

its record-breaking rise.

Engineers in Colorado are
racing to build a mega dam to

help secure
the state's water supply.

They must raise the height of
the old Gross Dam by 131 feet

to triple the capacity of
the reservoir behind it.

To do this, engineers must
build a supersized wall made

from 118 giant steps to sit on
top of the existing structure.

For many large
construction projects,

engineers traditionally
pour concrete into

a steel framework.

But cutting and welding
thousands of feet of steel for

the new Gross Dam
will significantly raise costs

and risk delays.

To stay on schedule,
the engineers use a material

called roller compacted
concrete, or RCC.

A conveyor belt system delivers
concrete to a fleet of

specially tracked dump trucks
at the base of the dam.

These tip the concrete into
predetermined positions.

Bulldozers smooth it out.

Heavy rollers then compress
this layer

before an excavator with
a vibrating pad compacts it

tightly together to
increase its strength.

Each step rises about
50 inches by 24 inches.

The team will build
118 steps in total

to make the new dam
471 feet tall.

It's like watching an orchestra
where there's a conductor

and the conductor knows what
every single one of

the musicians are doing,

and everybody's
doing their part.

This is a 24/7 operation.

There's two shifts every day,

and then there's
seven days continuously.

The dam extension needs over

17 million cubic feet
of concrete.

That's over 15% more than
the old dam.

It's up to project manager
Jeff Martin to make sure that

a steady supply of concrete
reaches the build

to keep it on schedule.

We are gonna create
a massive amount of concrete to

build the dam itself.

We have over 300 people here
working every day

and we need to make sure
we can always have the product

where our people are to put that
in and build the dam.

Trucking in building materials
would clog up the narrow

mountain roads for years

and put the project
over budget.

So Jeff and the team
build their own

concrete factory on site.

[Jeff]
We couldn't build this dam

without having
this concrete plant right here

next to the dam.

The plant operates 24/7 to
supply 16,000 cubic feet of

concrete an hour.

But building quickly with
concrete creates a problem.

[Jeff] Any time you mix water
and cement together,

it creates heat.
Heat creates expansion.

Once it cools,
it shrinks and cracks.

These cracks could become
weak points in the future.

In a dam, that's critical.

Water can force its way in,
building pressure and weakening

the structure over time.

To combat this,

engineers cool the concrete to
around 50 degrees Fahrenheit.

This limits heat buildup as it
cures, reduces expansion,

and helps to prevent cracks
from forming.

As you can see,
we're in our ice plant now.

This is where we create all
the ice that we put in

the concrete --
450 tons of ice a day

to go into our concrete mix
to keep

our concrete as
cold as possible.

With this project, we're using
80% ice in the concrete.

That's a key ingredient,
a key project recipe

to keep this
really cold concrete

that we have to make
for this project.

It's critical that the concrete
arrives cold to the site,

so the team builds a custom
conveyor system to transport it

quickly over the dam and down
to the waiting dump trucks.

These tip the concrete
onto predesignated spots.

Bulldozers then spread it,

and rollers level it.

Finally, a compactor
hammers the concrete.

[Felipe]
The reason we use a compactor
is to achieve the right density

that it needs to have
the compressive strength

and the properties that
we need for the raised dam.

The compaction process forces
out a cement paste that helps

to strengthen the layers
of the dam.

[Felipe] After the compaction,
paste comes up to the surface,

and that paste going to
the surface is what

allows us to,
when we place the next layer,

to get the right bond
between the two

so that it's like
it was placed monolithically.

You can't even tell that it was
placed in two different layers.

The density of the concrete
makes the wall of the new

Gross Dam strong enough

to hold back
billions of gallons of water.

But it's vulnerable to
the harsh climate

of the Rocky Mountains.

Roller compacted concrete
itself is not super durable

against freeze-thaw
and the elements.

If we just left the roller
compacted concrete exposed,

over time, moisture would seep
into it, and it would go

through freeze-thaw cycles
during our cold seasons,

and that could degrade
the concrete and chip it away,

and it could break down
over time.

The engineers must
weatherproof this layer.

So, they encase it in a nearly

10-inch-thick layer of
regular concrete.

Workers pour
the weatherproofing layer of

concrete in tandem with
the RCC concrete.

It's critical that every layer
is the same thickness.

[Casey]
It's really important as we go
that each step is built to

the exact correct dimensions so
that when we get to the top of

the dam, 118 steps up,
that we end up at

the correct elevation.

Using GPS,
the team continually

monitors the steps
to make sure

they're constructed at
the correct height.

Nearby, a second team is
tackling the water storage

problem in a different way,
constructing an entirely

new reservoir
from the ground up.

Engineers in Colorado are
racing to secure the state's

water supplies in the face of
continued droughts.

Their solution is to store more
of the ice melt every year.

Nearly 30 miles north of
the new Gross Dam project,

a second team is working on

another mega water
storage solution.

Engineers here are constructing
an entirely new reservoir

from the ground up.

The Chimney Hollow Reservoir
will store over

29 billion gallons
of water,

held back by a unique dam built
from rock and asphalt.

Combined with the Gross Dam,
this mega build will help

stabilize Colorado's fragile
water supply.

Jeff Drager and Becky Brush
lead the project.

There hasn't been anything
done like this before.

Chimney Hollow is the first
reservoir built within

the last 25 years, which is
a pretty incredible feat.

To hold back the vast amounts
of liquid, the engineers are

building a dam that's 350 feet
tall and 3,700 feet long.

First, workers will blast
the weathered rock to expose

the stable bedrock underneath.

Next, they'll lay an
18-inch-thick concrete plinth

across the valley.

A giant drilling machine will
then bore 2,000 holes 230 feet

into the bedrock and fill them
with grout to make

a watertight curtain beneath
the ground.

Above it, a special machine
will lay 512 layers of

an impermeable asphalt concrete

to form the core of
the Chimney Hollow Dam.

Earthmovers will shift over 315
million cubic feet of rockfall

to support it.

The first challenge
the engineers face is building

a solid foundation
for the megastructure.

The rock here is too tough for
machines to dig away.

The excavators can dig rock
that's up to a certain hardness.

But once you get down further
into the rock, it's just

too hard -- an excavator just
can't dig it.

So, Jeff and his team detonate

millions of pounds
of explosives

to smash through the rock.

It's a lot of explosions,
probably one a day

for about a year.

[explosion blasts]

[explosion blasts]

Once they've exposed
the bedrock, the engineers

move on to the next challenge,

constructing
the foundation plinth.

This 3,700-foot-long wall

locks the Chimney Hollow Dam
to the rock.

[Becky]
It's really important to get
the plinth right because that

is the foundation for the main
dam, so everything is built on

top of that,
and if that goes wrong,

the whole dam will be off.

Engineers fabricate boxes from

thousands of feet of
steel rebar

and place them inside wooden
forms that extends

the full length of the plinth.

The boxes are then pumped full
with super strong concrete.

It takes the team almost two
years to complete the plinth.

Engineers can now build
the main dam.

But they face a new challenge.

Most of the dams here in
Colorado are built with

earthwork and rock.

Most of them have
what we call a clay core.

Clay is impermeable,
and it prevents water from

leaking through the clay so

that your dam actually
holds water.

On our site, we don't
have very much clay.

So we needed to find another
way to keep the water from

leaking out of the dam.

Jeff and the team make
the bold decision to build

the core of the dam
from asphalt.

The technique is common
in Europe

but rare in the United States.

My first thought was, I don't
want to do an asphalt core dam.

It's not been done in Colorado.

I don't want to be
a guinea pig.

But over time, I was convinced
that that was a good way to go.

[horn honking]

The engineers bring in
a special paving machine

to do the job.

It works like a 3D printer.

As it advances, it lays down

a three-foot band of
flexible asphalt

and two bands of gravel on
either side that lock

the waterproof core
into position.

For almost three years,
the machine travels up and down

the dam over 500 times to build

it up to its full height
of 350 feet.

The asphalt and gravel core is
too weak on its own to

hold back billions of gallons
of water.

To make the dam strong,
engineers must build two large

rock embankments on either side
of the waterproof core.

To feed the operation,
the engineers transform

a part of Chimney Hollow

into one of the largest
quarries in Colorado.

At its peak, it produces over

68,000 tons of material
every day.

Supersized dump trucks haul
the rock to the dam.

The quarrying operation
runs 24/7

to keep the dam
builders supplied

with a steady stream
of rock.

But the reservoir is just one
part of the water storage

solution in Colorado.

The challenge for engineers is
to reliably deliver thousands

of gallons of water to
where it's needed.

The steep terrain of
the Rocky Mountains

makes that difficult.

So the team builds
a vast new network

of infrastructure
around the dam.

First, they excavate
a 2,000-foot-long access tunnel

through solid rock.

This will house the giant
pipelines that carry water into

and out of the reservoir.

Next, they construct a valve
house to control the flow

of water through the system.

The team also builds a huge
concrete spillway capable of

releasing excess water safely
during extreme weather.

And because this site sits high
in the Rockies, engineers must

construct new roads
and bridges to reach it.

All of these systems must
operate together.

After four years of
construction, the giant dam

and its supporting
infrastructure

are finally complete.

What engineers must now do is
protect the dam from

an unexpected
but common threat --

flooding.

Engineers are racing
to guarantee

Colorado's future water supply.

Rebuilding Gross Dam will
increase the reservoir's

capacity by over 183%.

But that creates
a major problem.

As the water rises, it could
exploit natural low points in

the surrounding landscape.

If we have a flood
and the reservoir comes up,

the water is actually going to
go out a different area that

we don't want it to go out.

Enlarging Gross Dam will raise
the reservoir's water level

by nearly 140 feet.

A sudden flood could increase
the water level even higher.

There's a risk that the rising
water could escape through

a low point in
the surrounding valley.

To stop that from happening,

engineers build a second
barrier known as

a saddle dam.

First, crews excavate down to
solid bedrock.

Then they backfill the cut with
thousands of tons

of roller-compacted.

The finished structure stands
40 feet high and stretches

roughly 590 feet
across the landscape.

Covered with natural
vegetation, the saddle dam

seals the gap to prevent water
from escaping from

the reservoir during
extreme floods.

The huge new Gross Dam
will be an arch dam.

The curved shape of
the structure transfers

the pressure of the water
sideways into

the surrounding canyon walls.

The saddle dam is different.

So unlike the main dam,
which is an arch dam,

the Saddle Dam is a gravity
structure, so it holds itself

in place under its own weight.

Crews must build
the saddle dam

from layer after layer of
dense roller-compacted concrete

to give it the strength
it needs.

Right here,
we're transitioning from

one layer to the next.

You can see this layer,
another layer here,

and they just keep coming in
all day long, dumping out

roller-compacted concrete,
spreading it into these layers,

vibrating it,
rolling it into place,

making sure
it's hard and set up.

The saddle dam's location
presents engineers

with a challenge.

It's over half a mile from
the on-site plant that makes

the special cold concrete
the dam needs.

Their solution is to deploy
a fleet of dump trucks.

These work in rotation to
deliver the concrete

at the correct temperature.

This operation over here
is continuous.

We have one truck right
after another.

One truck is backing in.

There's another truck out there

waiting to back in right behind
them and dump their load.

Once dumped,
it's critical that the concrete

is spread quickly
and to the right height.

So, the engineers equip each
bulldozer with a special

GPS system that tells
the driver where to spread it.

[equipment beeping]

It uses, basically,
satellites to know exactly

where, what elevation they're
at, where they are in space.

Then they can place the
material to exact tolerances.

Next, crews
compress the concrete.

This reduces its volume by 15%
and forces out air to create

a dense, impermeable structure.

[Casey]
This piece of equipment here
that rolls it into place,

and then you can see how it
gets smooth.

The concrete is hard
enough to walk on

after only a few minutes.

Once complete, the saddle dam
will prevent overflow from

threatening the valley
below the reservoir.

We've been planning this work
for a really long time.

It's great to see it finished
off so that we can move on

and continue the rest of
the project

and get things
wrapped up around here.

Now, engineers must tackle
something that could threaten

the stability of
the entire structure.

Engineers in Colorado are
supersizing the Gross Dam to

help secure the state's future
water supply.

Reservoirs need a way to safely
release excess water when

water levels rise too high.

To do that, engineers build
them with spillways.

These channels often direct
flood water down the face of

the dam and safely back into
the river below.

But at Gross Dam,
enlarging the spillway creates

a dangerous problem.

The overflowing water strikes
the bottom of the dam,

a zone called
the stilling basin,

with enormous force,

after it plunges down
the stepped concrete chute.

That energy could threaten
the stability of

the structure itself.

The concern is with the new
steps, the force of the water

could just create too much
energy at the base, which then

erodes the foundation
and creates a hole

right underneath our new dam.

To solve the problem,
Gross Dam's designers turn to

hydro engineers at
Colorado State University.

The team builds a scale model

of the new spillway
and stilling basin.

Then, they simulate extreme
floods to measure how the water

behaves as it crashes
down the dam.

The tests reveal a solution.

Engineers must build giant
triangular-shaped concrete

structures called baffle blocks
inside the stilling basin at

the base of the spillway.

These structures break up
the flow of water and reduce

its destructive energy before
it reaches the river below.

We learned from that model how
large to make these

baffle blocks,
how far to space them

from the dam,
how long to make

the stilling basin itself,
and how tall to make

these stilling basin walls so
that all the water would stay

inside this structure.

Now engineers must build
the system in real life.

First, crews construct
the stilling basin

at the foot of the dam.

Then, they install 11 massive
concrete baffle blocks

across its floor.

Next, crews pour towering
reinforced-concrete walls

around the basin itself.

To prevent the turbulent water
from escaping and eroding

the surrounding ground,
the walls must be built

strong enough to withstand
the immense force

of the falling water.

[Casey]
So these walls are what
we're building today.

They're full of reinforcing
steel, and these guys are

pumping conventional concrete
into these walls.

You can see the workers above

vibrating the concrete into
place and making sure it's all

consolidated and properly
installed so that when we pull

this formwork off,
we have a nice,

smooth, finished product.

Together, the spillway
and stilling basin form

a giant safety valve

to protect Gross Dam during
the most extreme floods.

The safety features of the dam
extend beyond the spillway.

It's critical that the new
extension moves slightly

upstream as the reservoir
pushes against the structure.

That movement helps
to lock the dam

into its final super-strong
arch shape.

But if the dam moves the wrong
way, the concrete could crack.

Dam safety engineer
Erin Gleason

oversees a vast network
of sensors

that monitor both structures.

[Erin]
We have lots of sensors --

hundreds, in the new dam
and the existing dam,

and all of them work together

so that as we construct the new
dam, we're ensuring that

it's compatible with
the existing dam and that at

the end of construction,
we'll have a safe structure.

Joint meters measure
the movement between

the original concrete blocks of
the old dam.

The engineers expect to see
a change as the new dam's

roller compacted concrete
pushes on it.

So as the RCC is placed
and heats up and cures on

the downstream side of the dam,

that heat expands the concrete

and then pushes
the existing dam upstream.

And so we're trying to figure
out how much of that expansion

and contraction of the joints
is due to the new RCC.

If the joints widen,
engineers know

the new extension is pushing
the dam upstream as designed.

If the joints contract,
the dam could be moving

in the wrong direction.

[Erin] And that could make it
prone to cracking.

And cracking is not what
we want to see on --

on a arch dam or any dam.

Survey prisms mounted
on the dam monitor

vertical movement across
the structure.

Any upward shift could indicate

the dam is pulling away
from its foundations.

Back in the control room,
Erin analyzes the data

in real time.

Over on this screen,
we have the survey prisms,

the vertical movement of
the survey prisms.

And that's showing no movement,
no vertical movement,

which is good.

This specifically is
the joint meter instrumentation,

and it shows that further
upstream movement is occurring.

So that's exactly what
we were expecting to see

and hoping to see,
and so that just confirms

that we have concrete
that is not going to crack.

The readings confirm
the structure remains stable

and the expanded Gross Dam is
performing exactly as designed.

Now, engineers must solve
one final problem before

they can complete the project.

Ensuring the dam is watertight.

Engineers in Colorado are
racing to finish

the mighty Gross Dam.

They must solve
one final problem

before they can complete
the project.

The concrete walls of the dam
are designed to

hold back the reservoir.

But the rock surrounding
the structure

is not completely watertight.

Water can seep through
tiny cracks and fissures in

the canyon walls
beside the dam.

Over time, that leakage could
weaken the surrounding rock

and threaten the stability of
the structure itself.

Specialist Jessie Strobel
has been working

on the project for four years.

This is by far the biggest
project I have ever worked on.

I have never seen anything this
big being built.

This is gonna be one for
the record books

and the resume.

The solution is to
build a giant

underground waterproof barrier
inside the rock itself.

Known as a grout curtain,
it seals cracks deep beneath

the surface and blocks water
from passing through.

[Jessie] The old dam did have
a grout curtain

that extended up to
the top of it,

but this dam is going to be
over 140 meters high,

so we have to extend
the grout curtain the rest of

the way up to the top of
the dam so it can hold back

the reservoir water
once it's filled.

To extend the height of
the grout curtain,

the crews first drill deep into

the canyon walls
around the dam.

The machine drills holes tens
of meters into the ground to

make sure that we are getting
as far down as we believe any

reservoir seepage
can go through.

Then, after
it's drilled the hole,

it continues to stay in place
and then injects the grout

through tubing all the way in
to make sure that

we are filling those tens of
meters with all of the grout

and really forming
that strong barrier.

We don't know exactly what
all the rocks look like

100 feet down, so we just
keep feeding grout

in through the machine
until it stops taking any more.

Together, these injections
form a vast underground curtain

designed to stop water from
escaping around the dam.

But seepage creates another
danger beneath

the structure itself.

Groundwater can still force
its way underneath the dam.

When you're engineering a dam,
you don't just need to think

about holding the water back
behind the reservoir,

but you also have to think
about how the groundwater is

going to want to move as well.

Because if pressure is put on
the dam from the groundwater,

it's gonna start lifting
the dam up, and that is just

not what you want to be able to
hold back a reservoir.

That movement
could separate the dam

from the bedrock
holding it in place.

The result
could be catastrophic.

The team needs
another solution.

Deep inside the dam,
crews construct

a vast drainage system
designed to relieve

the pressure
beneath the structure.

From here, crews drill hundreds
of long drainage holes deep

into the foundation below.

The drainage holes intercept
the ground water,

and channel it into
the galleries inside the dam.

From here, the dam can release
it into the river downstream.

The existing Gross Dam was
pretty watertight,

but you could still fill up
a glass of water in about

a minute from the seepage that
was coming through.

So we would hope with
the raised dam, to keep that

same level of watertightness,
but still have some seepage.

So that's why we have
the foundation drains being

built in, it's for any water
that does come in,

it goes where we want it to go
and doesn't start moving around

and moving things that
we don't want to be moved.

This super drainage system,
together with

the grout curtain,
will help to keep Gross Dam

locked securely to the canyon.

To complete Colorado's mega
water projects,

engineers excavated deep in
the Rocky Mountains...

[explosion blasts]

...raised one of the state's
largest dams

to record-breaking heights...

and built a vast new spillway
and underground drainage

systems to protect it from
the immense pressure of

the reservoir behind it.

What we've created is really
a testament not only

to engineering,
but of construction innovation.

Now, the new and expanded dams
will help provide fresh water

for millions of
Colorado residents,

and safeguard the state's water
supply against future droughts

for generations to come.