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This time, we reveal the relentless struggle

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to keep water flowing to our cities.

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One of these pops can fill up

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an Olympic sized swimming pool in 20 seconds.

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The hidden army working to keep our water safe.

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You've got a less than 15 minutes lifespan

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once you enter into this water.

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And the future of our water waste.

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People flush their toilet

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and it turns into fuel for cars and buses.

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Half the world's population

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live in urban areas and the number is rising every second.

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Each day is a race against time

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to house, feed, water and move more than 3.5 billion people.

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It's an impossible daily challenge.

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The slightest glitch can bring a city to its knees

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and every 24 hours, it has to be done all over again.

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This is the story of how cities work.

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(upbeat music)

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For centuries, cities have been built

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near a fresh water supply.

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Without it, we'd be lucky to live three days.

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But this most basic human need can be deadly too.

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Get the supply wrong and it can poison us.

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Get too close and it can drown us.

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Water,

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we need it and must respect it.

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With every passing year,

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the challenge of providing water to billions of people

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becomes harder and harder.

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Nowhere is this more apparent than the city of Los Angeles.

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(dramatic music)

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This is the key to LA survival.

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The Hoover Dam on the mighty Colorado River.

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It is a whole state away,

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but the reservoir it controls, Lake Mead,

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is a critical supplier of drinking water to the city.

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The route to LA runs 250 kilometers

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downstream to the Colorado river aqueduct.

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Greg Hare is one of the pilots charged

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by the authorities in Southern California

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with keeping this precious structure safe.

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When I'm doing security patrols,

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I'm mainly looking for people

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who aren't supposed to be there.

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If I see something that I believe is suspicious,

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I will call our dispatch office and have them

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take the appropriate action.

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(tension music)

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This manmade aqueduct

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provides Los Angeles and Southern California

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with approximately 4 billion liters of water a day.

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Because of its importance to the state,

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surveillance was heightened after the 9/11 attacks.

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Our special security patrols

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are tied to whatever the terrorist alert level is.

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But it's a huge challenge.

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The Colorado river aqueduct is a 389 kilometer network

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of tunnels, canals and pumping plants.

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It's sheer size makes it virtually impossible

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to protect efficiently from the ground.

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We patrol the aqueduct with the airplane

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from the air.

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The reason we do that

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is because we can cover the entire length of the aqueduct.

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But Greg's aerial patrol

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allows him to police the remotest points

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of the aqueducts route where few ground patrols

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are able to reach.

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Desolate areas where people aren't around to watch it,

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you could have something going on out there

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that you wouldn't know about unless you could fly out there

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and take a look at it real quick.

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People aren't the only threat.

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Greg and his team run constant checks

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to scan the waterway for signs of damage.

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(suspenseful music)

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The aqueduct must carry the city's water

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across no less than three hostile mountain ranges.

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In the 70 years since it was built,

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the population of California has risen by more than 500%.

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The aqueduct is a backbone of our water supply system.

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It's been the most reliable

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delivery of water for the last 70 years

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for Southern California.

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The challenge was to get water from the Colorado river,

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some 242 miles, into Southern California

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over several mountain ranges in a very dry and hot desert.

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Don Nash oversees all five pumping stations

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along the aqueduct, including the Julian Hind's Plant.

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We're at Hind's Pump Plant.

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This is the last lift on the Colorado River aqueduct.

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It's taken about 25 hours for the water to get here

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from the Colorado River.

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This station is the last and most powerful

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of the pumping stations.

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Each day, it must defy gravity

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to lift over 4 million tons of water

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over 130 meters to the top of Eagle mountain.

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And this is the last 441 feet it takes

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to overcome the last mountain range

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to get us into Southern California.

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The power needed

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to lift the water is staggering.

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There's one pump of nine that we have here.

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One of these pumps can fill up an Olympic sized swimming

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pool in 20 seconds.

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It's actually discharging right here underneath our feet

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and going up the hill some 441 feet to the top of the hill.

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Don's 912,500 horsepower pumps

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lift water over the mountains,

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but there's another natural threat

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waiting just on the other side.

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(tense music)

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This is Lake Mathews,

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the final reservoir on the Colorado River aqueduct

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where the city's water is stored

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before flowing into LA for treatment.

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Storing vast quantities of water in the middle of the desert

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produces unexpected challenges.

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The lake is a breeding ground for tiny intruders.

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The advantage of having water in a lake

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is that you can store it.

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The disadvantage is that now it's a large enough reservoir

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that is going to behave as a lake.

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Dr. Rick DeLeon and his team of divers

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are fighting an ongoing battle

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against the mighty army of small,

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but persistent quagga mussels.

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These mussels can actually grow to very high densities.

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100,000 per square meter is not uncommon.

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They have been documented to grow up to 700,000

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per square meter.

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The mussels have no direct effect

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on the quality of the water,

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but if left unmonitored,

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they could block supply pipes to the city

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with potentially devastating consequences.

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And when the mussels colonize,

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they can actually close that space

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and not allow much water to go through

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and put a strain on the pumps.

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So they need to be removed

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to allow the water to go through uninterrupted.

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(suspenseful music)

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Dr. DeLeon and his team

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place test plates in the lake to monitor

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the mussels growth rates.

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Today, divers Steve and Kelly,

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are retrieving one that's three months old.

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(tense music)

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Steve and Kelly, are the quaggas growing just on

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just rocks or are they also growing on the silt?

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Just on the,

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just on the rocks at this point.

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I think (indistinct).

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After a 30 minute dive,

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Steve rises to the surface with the test plate.

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It is completely covered in quagga mussels.

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That's surprising how

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much they're still growing in there.

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What depth was this?

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This was 53 feet.
<v ->53.

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So deeper than we thought.

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The test plate reveals

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a steady increase in the number of quaggas.

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One of the reasons why we monitor is to see

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is there frequency of which they need to go in there

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and clean up.

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For Dr. DeLeon,

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this means that not long from now

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a full-scale unblocking operation will be needed

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to keep water flowing to Los Angeles.

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For us, it's really a matter of control over time

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to reduce the impact that it can have on us

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and prevent them from interfering

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with our normal operations.

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Humans cannot survive without a constant supply

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of drinking water.

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In the next 20 years,

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our cities will grow to such a point

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that demand will outstrip supply

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from rivers and lakes by 40%.

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For cities like Barcelona,

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that means a constant battle against drought.

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The impact is already being felt by Aigues de Llobregat,

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{\an8}one of the city's main drinking water suppliers.

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{\an8}We have not enough water to supply all these people.

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In the last five years,

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Barcelona has turned to a radical new source

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that could solve supply problems forever,

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seawater.

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But seawater has a higher salt content

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than the human body can process.

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Drinking large quantities could result in death.

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In 2009, the city built the biggest desalination plant

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of its kind in Europe on Catalonia's shoreline.

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Overseen by plant director,

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Carlos Miguel Centeno.

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(Carlos speaks in a foreign language)

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This brightly colored super hub of pipes and pressure pumps

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is equipped to bring an average of 200 million liters

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of sea water into the plant a day.

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To make it drinkable,

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it's killer salt content needs to be removed.

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This desalination happens

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through a process called reverse osmosis

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and takes place inside these blue tubes.

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Seawater is pumped through a coiled membrane

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fine enough to filter out the salt molecules in the water.

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It allows pure water

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to flow through to the next stage of its treatment.

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And just minutes into the day shift,

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engineers have found a problem with a pressure pump.

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Carlos Miguel must act fast.

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A faulty pump could seriously impact

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Barcelona's water supply.

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(Carlos speaks in a foreign language)

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Seawater can't keep flowing in

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during the membrane change

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so the control room shuts down a section of the plant.

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This is not good news for Carlos Miguel

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as less water is now available to the city.

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Changing membranes is no easy task.

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These seven heavy cylinders

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must be perfectly placed in their tube

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for their power and pressure connectors to work.

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The team add a coat of glycerin

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to ensure they slide in smoothly,

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and apply some heavyweight muscle.

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Once the tube is tightly sealed,

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the pump can startup again,

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bringing supply back to full capacity.

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Pumping seawater through an army of over 17,000 membranes

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is not enough to guarantee a safe drinking supply.

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The city's water must go through several purification stages

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before it's fit for consumption.

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And it's here in the plant's laboratory

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where critical testing takes place

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before releasing drinking water into the city.

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(Carlos speaks in a foreign language)

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Biochemist Maria (indistinct)

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leads a team of scientists

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whose job it is to test samples

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from every step of the process.

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After its journey from the sea and a battle against time,

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this water is now safe for the city to drink.

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Desalination is important for Barcelona

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because with this new supply of water,

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we have 20% of the water that Barcelona needs.

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Barcelona's use of the sea

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could be at the forefront of a water revolution,

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a way to guarantee future supply

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for the world's growing city populations.

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(suspenseful music)

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Cities don't just depend on water for drinking.

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Waterways provide a vital transport link for moving goods

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in and out of our cities.

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London Gateway.

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Today engineers are taking delivery of a fleet of cranes

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among the biggest in the world.

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They're approaching British shores

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after a six week journey from Shanghai.

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This marks a turning point for London.

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These key cranes are capable of unloading

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some of the largest cargo ships in the world

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at unprecedented speed.

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Engineer, Russ Broughton is supervising the unloading.

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It's a really big day

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in the life of London's nearest port.

271
00:14:36,820 --> 00:14:38,970
Yeah, we're all very excited about it here.

272
00:14:40,620 --> 00:14:42,395
The UK is an island nation

273
00:14:42,395 --> 00:14:46,760
{\an8}and 90% of our goods come in by sea

274
00:14:46,760 --> 00:14:51,230
{\an8}and it's nothing new to have our ports in London.

275
00:14:51,230 --> 00:14:54,333
It's what the Romans first did 2000 years ago.

276
00:14:55,600 --> 00:14:57,170
It may be the same waterway

277
00:14:57,170 --> 00:14:59,060
but London is now a capital city

278
00:14:59,060 --> 00:15:00,950
with millions of inhabitants.

279
00:15:00,950 --> 00:15:04,060
The key point is that this is the biggest consumer market

280
00:15:04,060 --> 00:15:05,120
in the UK.

281
00:15:05,120 --> 00:15:08,760
This is Europe's largest economic area.

282
00:15:08,760 --> 00:15:09,940
So we're once again,

283
00:15:09,940 --> 00:15:11,980
gonna bring the biggest ships in the world

284
00:15:11,980 --> 00:15:14,313
to the biggest point of consumption in the UK.

285
00:15:15,260 --> 00:15:17,410
To do that, we need some big pieces of kit.

286
00:15:19,400 --> 00:15:23,110
Each crane is 138 meters tall,

287
00:15:23,110 --> 00:15:24,513
taller than the London Eye.

288
00:15:26,770 --> 00:15:28,780
It's the culmination of years of planning

289
00:15:28,780 --> 00:15:30,663
and millions of pounds spent,

290
00:15:32,350 --> 00:15:34,063
but Russ and his team are worried.

291
00:15:35,960 --> 00:15:37,410
There's no crane in the world

292
00:15:37,410 --> 00:15:40,750
big enough to lift each 2000 ton steel structure

293
00:15:40,750 --> 00:15:41,923
onto dry land.

294
00:15:44,410 --> 00:15:45,670
The only way to unload them

295
00:15:45,670 --> 00:15:47,673
is by dragging them off the ship.

296
00:15:49,270 --> 00:15:51,250
This can only happen at high tide

297
00:15:51,250 --> 00:15:53,747
when the deck is level with the quayside.

298
00:15:54,898 --> 00:15:56,820
The tide is flowing pretty quick at the moment.

299
00:15:56,820 --> 00:15:58,090
Then we've got one hour

300
00:15:58,090 --> 00:15:59,943
to get this crane back onto the land.

301
00:16:01,060 --> 00:16:03,970
It's 2000 ton, we're on a moving vessel

302
00:16:03,970 --> 00:16:05,530
and if we don't do it in that hour

303
00:16:05,530 --> 00:16:07,820
then we ended up with 2000 ton of metal

304
00:16:07,820 --> 00:16:09,440
sticking out at the Thames

305
00:16:09,440 --> 00:16:11,733
and I'm not sure how we're going to get that out.

306
00:16:13,020 --> 00:16:14,920
The ebb and flow of the Thames tide

307
00:16:14,920 --> 00:16:18,213
can change water levels by a massive seven meters.

308
00:16:19,580 --> 00:16:23,473
Russ and the team only have one shot to get it right.

309
00:16:24,825 --> 00:16:27,040
To roll the crane off the ship,

310
00:16:27,040 --> 00:16:28,510
engineers must lay down

311
00:16:28,510 --> 00:16:31,333
four industrial sized bridging tracks.

312
00:16:34,060 --> 00:16:36,830
The vessel and the dock must be perfectly aligned

313
00:16:36,830 --> 00:16:38,353
for the crane to slide off.

314
00:16:41,470 --> 00:16:44,263
The tracks must be fitted in a matter of minutes,

315
00:16:46,280 --> 00:16:48,800
but the team can't begin to put them into position

316
00:16:48,800 --> 00:16:51,423
until the ship and the quayside are almost level.

317
00:16:53,000 --> 00:16:53,833
This is it now.

318
00:16:53,833 --> 00:16:54,820
This is the last couple of minutes

319
00:16:54,820 --> 00:16:57,180
to just put the final bridge in to position.

320
00:16:57,180 --> 00:16:59,830
Any second now, this crane's gonna start rolling off.

321
00:17:01,260 --> 00:17:02,880
The rails are aligned,

322
00:17:02,880 --> 00:17:04,563
but the worst is not over.

323
00:17:05,960 --> 00:17:07,230
Yeah, this is it.

324
00:17:07,230 --> 00:17:08,577
the ropes are all gone tight now

325
00:17:08,577 --> 00:17:10,880
and you can see the crane starting to move.

326
00:17:10,880 --> 00:17:12,450
This is the bit that we've all been waiting for

327
00:17:12,450 --> 00:17:14,703
and it's do or die.

328
00:17:16,060 --> 00:17:19,423
They must make this work or risk costly delay.

329
00:17:20,770 --> 00:17:22,200
We're now at high tide.

330
00:17:22,200 --> 00:17:23,780
We've got about 45 minutes to an hour

331
00:17:23,780 --> 00:17:25,793
to get this off safely onto the land.

332
00:17:26,930 --> 00:17:29,660
There's another complication Russ can't control.

333
00:17:29,660 --> 00:17:32,413
So he relies on engineers aboard the vessel.

334
00:17:35,960 --> 00:17:37,380
As the crane is unloaded,

335
00:17:37,380 --> 00:17:40,063
its weight threatens to destabilize the ship.

336
00:17:42,700 --> 00:17:43,730
To keep it level,

337
00:17:43,730 --> 00:17:46,470
engineers must pump thousands of liters of water

338
00:17:46,470 --> 00:17:49,480
into the ballast tanks on the other side of the ship.

339
00:17:49,480 --> 00:17:50,610
If they get it wrong,

340
00:17:50,610 --> 00:17:53,603
the crane could slide off the ship and into the Thames.

341
00:17:59,949 --> 00:18:01,770
On the quayside,

342
00:18:01,770 --> 00:18:05,530
engineers have wired in a network of winches, pulleys

343
00:18:05,530 --> 00:18:06,853
and wire ropes.

344
00:18:15,220 --> 00:18:19,400
This choreography of slow but meticulous pushing and pulling

345
00:18:19,400 --> 00:18:22,240
begins working in combination to control

346
00:18:22,240 --> 00:18:24,713
every move of this giant structure.

347
00:18:30,800 --> 00:18:33,470
A sudden movement or level change in the water

348
00:18:33,470 --> 00:18:34,520
could spell disaster.

349
00:18:36,032 --> 00:18:39,032
(suspenseful music)

350
00:18:59,160 --> 00:19:02,430
It's taken over 40 minutes of coaxing,

351
00:19:02,430 --> 00:19:05,193
but finally the crane makes it onto dry land.

352
00:19:10,730 --> 00:19:12,330
The final bit is just to get an inch perfect

353
00:19:12,330 --> 00:19:14,030
so when we lower it down,

354
00:19:14,030 --> 00:19:17,350
then I want to see it lands centrally on the rails.

355
00:19:17,350 --> 00:19:19,470
British and Chinese engineering teams

356
00:19:19,470 --> 00:19:21,383
have completed this mission.

357
00:19:21,383 --> 00:19:24,880
And the construction of London's newest port

358
00:19:24,880 --> 00:19:27,770
is a step closer to realization.

359
00:19:27,770 --> 00:19:29,307
Thankfully, there were no problems on this one

360
00:19:29,307 --> 00:19:30,807
and it all went very smoothly.

361
00:19:33,880 --> 00:19:35,010
Very happy here.

362
00:19:35,010 --> 00:19:36,340
Sweet, isn't it?

363
00:19:36,340 --> 00:19:38,390
You never know but it all went very well.

364
00:19:44,770 --> 00:19:47,950
Waterways may serve to expand our cities,

365
00:19:47,950 --> 00:19:51,333
but rivers can be treacherous pathways for city dwellers.

366
00:19:52,820 --> 00:19:56,520
Hundreds of boats carrying thousands of passengers

367
00:19:56,520 --> 00:19:58,343
use the Thames every day.

368
00:20:00,640 --> 00:20:03,370
Most journeys go off without incident

369
00:20:03,370 --> 00:20:05,970
but the river can be a dangerous place.

370
00:20:05,970 --> 00:20:08,070
There's many hazards on the Thames,

371
00:20:08,070 --> 00:20:10,220
mainly the tide and the traffic.

372
00:20:10,220 --> 00:20:12,390
So other the vessels going up and down

373
00:20:12,390 --> 00:20:13,660
and the weight and tide,

374
00:20:13,660 --> 00:20:17,620
more barges and boats and bridge piers.

375
00:20:17,620 --> 00:20:19,300
This is a difficult environment

376
00:20:19,300 --> 00:20:21,253
for the rescue workers who police it.

377
00:20:22,170 --> 00:20:24,400
Last year, the emergency services

378
00:20:24,400 --> 00:20:27,740
were called out over 850 times,

379
00:20:27,740 --> 00:20:30,120
making this the busiest stretch of water

380
00:20:30,120 --> 00:20:31,603
in the country for rescuers.

381
00:20:33,880 --> 00:20:36,840
It's the job of the Royal National Lifeboat Institution,

382
00:20:36,840 --> 00:20:39,930
a charity operating along the coast of the British Isles

383
00:20:39,930 --> 00:20:42,333
to act as the river's first responders.

384
00:20:45,510 --> 00:20:48,860
Helmsman Stantod has served almost a thousand hours

385
00:20:48,860 --> 00:20:50,170
for the team.

386
00:20:50,170 --> 00:20:52,180
The Thames can be quite a ruthless beast.

387
00:20:52,180 --> 00:20:54,610
The currents and the coldness of the water

388
00:20:54,610 --> 00:20:56,170
coming down from the mountains.

389
00:20:56,170 --> 00:20:58,830
It makes it a very hostile place.

390
00:20:58,830 --> 00:21:00,330
This gives rescue services

391
00:21:00,330 --> 00:21:03,420
little or no time to save a casualty once they fall

392
00:21:03,420 --> 00:21:04,483
into the Thames.

393
00:21:05,450 --> 00:21:08,110
You've got less than 15 minutes lifespan

394
00:21:08,110 --> 00:21:10,421
once you enter into this water.

395
00:21:10,421 --> 00:21:13,088
(tension music)

396
00:21:14,780 --> 00:21:16,640
RNLI Tower Station base

397
00:21:16,640 --> 00:21:18,570
is one of four on the Thames

398
00:21:18,570 --> 00:21:22,460
set up in the wake of the 1989 Marchioness disaster

399
00:21:22,460 --> 00:21:24,623
which claimed 51 lives.

400
00:21:28,450 --> 00:21:32,870
Since then, the RNLI has rescued almost 3000 people

401
00:21:32,870 --> 00:21:34,063
from the Thames.

402
00:21:35,040 --> 00:21:36,750
For volunteer John Mullen,

403
00:21:36,750 --> 00:21:39,810
there's no other service completely committed to saving

404
00:21:39,810 --> 00:21:41,063
lives on the river.

405
00:21:42,140 --> 00:21:44,740
The river is a problem

406
00:21:44,740 --> 00:21:46,620
for the standard emergency services.

407
00:21:46,620 --> 00:21:51,620
So the RNLI presence here gives a committed rescue service.

408
00:21:52,010 --> 00:21:54,620
No other job, just to go out and help people

409
00:21:54,620 --> 00:21:56,100
that need the help here and there.

410
00:21:56,100 --> 00:21:57,690
The single biggest challenge probably

411
00:21:57,690 --> 00:21:59,750
is trying to prepare for an event

412
00:21:59,750 --> 00:22:02,643
that you don't quite know how it's gonna pan out.

413
00:22:04,380 --> 00:22:06,610
We've been to people that's been having babies,

414
00:22:06,610 --> 00:22:07,590
we've been to fires,

415
00:22:07,590 --> 00:22:09,300
we've been to people are stranded in the mud.

416
00:22:09,300 --> 00:22:10,510
It could be anything.

417
00:22:10,510 --> 00:22:13,027
That's part of the appeal of this job.

418
00:22:13,027 --> 00:22:16,300
(bell ringing)

419
00:22:16,300 --> 00:22:17,870
Right now, the London coast guard

420
00:22:17,870 --> 00:22:20,410
has issued an emergency call.

421
00:22:20,410 --> 00:22:24,490
The RNLI crew has 90 seconds to get on the water.

422
00:22:24,490 --> 00:22:26,830
On duty is helmsmen Michael Neild,

423
00:22:26,830 --> 00:22:30,649
and crew members Colin McCarthy and Giles Harrison.

424
00:22:30,649 --> 00:22:33,649
(suspenseful music)

425
00:22:35,120 --> 00:22:37,380
A suspected incident at Westminster Bridge

426
00:22:37,380 --> 00:22:40,773
has put all the capital's rescue services on high alert.

427
00:22:43,280 --> 00:22:46,513
Police, fire and ambulances are on their way.

428
00:22:47,619 --> 00:22:49,960
(indistinct) on the sea.

429
00:22:49,960 --> 00:22:51,200
But even more testing

430
00:22:51,200 --> 00:22:53,850
is the absence of information they're given.

431
00:22:53,850 --> 00:22:57,060
The information that comes through to the coast guard

432
00:22:57,060 --> 00:23:00,290
is, you know, usually done in a panic.

433
00:23:00,290 --> 00:23:02,620
It's not by any means the exact picture

434
00:23:02,620 --> 00:23:04,545
of what you're gonna get when you get there.

435
00:23:04,545 --> 00:23:06,380
(indistinct)

436
00:23:06,380 --> 00:23:08,677
We got a report of a male who threatened to jump

437
00:23:08,677 --> 00:23:11,239
the Westminster Bridge.

438
00:23:11,239 --> 00:23:14,270
{\an8}(indistinct) at this moment are able,

439
00:23:14,270 --> 00:23:17,600
{\an8}with surrounding cameras, to look on the bridge.

440
00:23:17,600 --> 00:23:19,620
If a person falls into the Thames,

441
00:23:19,620 --> 00:23:21,810
he or she only has minutes to live

442
00:23:21,810 --> 00:23:24,723
in water that's 10 to 15 degrees Celsius.

443
00:23:25,600 --> 00:23:27,894
After that, a fearsome undercurrent,

444
00:23:27,894 --> 00:23:30,893
and the chances of drowning are high.

445
00:23:34,260 --> 00:23:37,210
It's not clear whether anyone actually went into the water,

446
00:23:38,354 --> 00:23:39,400
but the emergency services

447
00:23:39,400 --> 00:23:41,673
have to take every report seriously.

448
00:23:44,730 --> 00:23:46,860
Crew members Michael, Colin and Giles

449
00:23:46,860 --> 00:23:48,783
search every meter of the river.

450
00:23:50,310 --> 00:23:53,870
The London Tower, we've searched both sides of the bridge.

451
00:23:53,870 --> 00:23:55,933
We've got nothing obvious.

452
00:23:56,831 --> 00:23:58,396
Fits your description if you don't have him.

453
00:23:58,396 --> 00:24:00,600
Five foot seven and medium build. Over.

454
00:24:00,600 --> 00:24:02,510
London Tower. Yeah, that was all received.

455
00:24:02,510 --> 00:24:03,690
Now an obvious-

456
00:24:03,690 --> 00:24:07,410
Helmsman Michael Neild needs to stay alert.

457
00:24:07,410 --> 00:24:10,010
Powerful currents surround the bridges foundations

458
00:24:10,010 --> 00:24:13,150
could easily suck their vessel into its walls.

459
00:24:13,150 --> 00:24:15,360
Nice. He's on his phone I think.

460
00:24:15,360 --> 00:24:16,483
Leaning on the side.

461
00:24:18,100 --> 00:24:19,490
There's no further information

462
00:24:19,490 --> 00:24:21,763
to suggest anyone did go into the water.

463
00:24:24,420 --> 00:24:25,993
It's starting to get dark.

464
00:24:27,170 --> 00:24:28,910
If there was anyone in the river,

465
00:24:28,910 --> 00:24:33,273
fast moving currents would have carried them far downstream.

466
00:24:35,620 --> 00:24:37,983
Eventually, the search is called off.

467
00:24:39,130 --> 00:24:40,430
Just no trace basically.

468
00:24:41,400 --> 00:24:43,263
Let's hope police have tried all avenues

469
00:24:43,263 --> 00:24:46,754
and got to a point where they decided that's it.

470
00:24:46,754 --> 00:24:48,428
There's no point in issuing anymore.

471
00:24:48,428 --> 00:24:51,178
(dramatic music)

472
00:24:53,530 --> 00:24:56,170
The team head back to their base.

473
00:24:56,170 --> 00:24:57,620
It's not a question of if,

474
00:24:57,620 --> 00:24:59,593
but when the next call will come in.

475
00:25:00,720 --> 00:25:03,290
And for these young unsung heroes,

476
00:25:03,290 --> 00:25:05,483
the battle on the Thames continues.

477
00:25:08,280 --> 00:25:10,310
I'm not sure I'd really wanna work anywhere else.

478
00:25:10,310 --> 00:25:11,450
There's always something going on here

479
00:25:11,450 --> 00:25:12,750
which is a nice thing.

480
00:25:12,750 --> 00:25:14,103
That's what I enjoy the most.

481
00:25:20,890 --> 00:25:23,128
Water can be our worst enemy,

482
00:25:23,128 --> 00:25:26,270
but it can also save our lives.

483
00:25:26,270 --> 00:25:28,210
It protects us from the most devastating

484
00:25:28,210 --> 00:25:30,400
of everyday disasters.

485
00:25:30,400 --> 00:25:31,233
Fire.

486
00:25:33,520 --> 00:25:37,320
In 2011, the US fire department received reports

487
00:25:37,320 --> 00:25:40,493
of structural fires every 65 seconds.

488
00:25:41,560 --> 00:25:43,110
We save lives

489
00:25:43,110 --> 00:25:45,460
and there is nothing more that you can do

490
00:25:45,460 --> 00:25:47,953
that's more gratifying than to save a life.

491
00:25:50,320 --> 00:25:53,420
In New York, there are almost 20,000 people

492
00:25:53,420 --> 00:25:56,550
per square kilometer that depend on the fire department's

493
00:25:56,550 --> 00:25:58,223
protection at all times.

494
00:26:00,720 --> 00:26:03,900
The entire force is helpless without fast access

495
00:26:03,900 --> 00:26:06,443
to massive amounts of high pressured water.

496
00:26:08,540 --> 00:26:13,290
This city solution is a network of 110,000 fire hydrants

497
00:26:13,290 --> 00:26:15,333
visible on every city street.

498
00:26:18,190 --> 00:26:20,380
They connect the city's water mains directly

499
00:26:20,380 --> 00:26:21,823
with the fireman's hose.

500
00:26:24,180 --> 00:26:26,050
For firefighter Michael Gallo,

501
00:26:26,050 --> 00:26:29,400
hydrants are critical in the fight against fire.

502
00:26:29,400 --> 00:26:30,910
Fire hydrants in the city of New York

503
00:26:30,910 --> 00:26:33,030
are of paramount importance.

504
00:26:33,030 --> 00:26:34,310
We rely on them.

505
00:26:34,310 --> 00:26:35,760
It doesn't matter how good my rig is

506
00:26:35,760 --> 00:26:37,760
or how fast they get there,

507
00:26:37,760 --> 00:26:40,228
without water we don't put fires out.

508
00:26:40,228 --> 00:26:42,978
(dramatic music)

509
00:26:44,383 --> 00:26:46,270
6:00 a.m.

510
00:26:46,270 --> 00:26:47,970
One of the city's vital hydrants

511
00:26:47,970 --> 00:26:50,280
has been knocked down by a car.

512
00:26:50,280 --> 00:26:52,240
The Department of Environmental Protection

513
00:26:52,240 --> 00:26:53,893
is dispatching a replacement.

514
00:26:56,800 --> 00:26:58,640
A broken hydrant could mean the difference

515
00:26:58,640 --> 00:27:00,013
between life and death.

516
00:27:01,370 --> 00:27:04,210
John Castiglioni and his team have just two hours

517
00:27:04,210 --> 00:27:05,523
to fit the replacement.

518
00:27:09,610 --> 00:27:13,023
But some hydrants in the city date back over 50 years.

519
00:27:14,834 --> 00:27:16,763
This is the lead from back in the day.

520
00:27:18,212 --> 00:27:19,650
As you see, it's soft.

521
00:27:19,650 --> 00:27:20,950
This was around the joint,

522
00:27:25,240 --> 00:27:27,003
and here's today's technology.

523
00:27:28,750 --> 00:27:29,833
See the comparisons.

524
00:27:31,440 --> 00:27:34,090
This rubber gasket stays in the retaining plan.

525
00:27:34,090 --> 00:27:37,638
Back in the day they didn't have that technology.

526
00:27:37,638 --> 00:27:39,073
The hydrant went in around the pipe

527
00:27:39,073 --> 00:27:40,870
and they used to make up the difference of space

528
00:27:40,870 --> 00:27:42,000
with the leg.

529
00:27:42,000 --> 00:27:45,200
Now today's technology, you're using a rubber gasket,

530
00:27:45,200 --> 00:27:46,313
the retaining gland,

531
00:27:47,710 --> 00:27:49,020
and the bolt.

532
00:27:49,020 --> 00:27:50,180
They go in.

533
00:27:50,180 --> 00:27:51,630
It holds everything in place.

534
00:27:52,701 --> 00:27:56,070
(dramatic music)

535
00:27:56,070 --> 00:27:57,380
As the work starts,

536
00:27:57,380 --> 00:27:59,570
there's an unusual amount of water coming out

537
00:27:59,570 --> 00:28:01,280
of the mains pipe,

538
00:28:01,280 --> 00:28:02,960
making the attachment of the hydrants

539
00:28:02,960 --> 00:28:05,473
retaining gland an impossible task.

540
00:28:11,120 --> 00:28:13,590
The team bring in a high powered suction hose

541
00:28:13,590 --> 00:28:15,703
to rid the area of excess water.

542
00:28:19,560 --> 00:28:21,466
For now we're gonna install the hydrant.

543
00:28:21,466 --> 00:28:24,020
Right on the hydrate branch,

544
00:28:24,020 --> 00:28:26,700
we're gonna fold it together to block it off,

545
00:28:26,700 --> 00:28:28,080
find the bolts up,

546
00:28:28,080 --> 00:28:28,913
lock up the back

547
00:28:28,913 --> 00:28:30,690
and then we're gonna all come to the hydrant gate.

548
00:28:30,690 --> 00:28:32,510
It makes you to hide your work properly.

549
00:28:32,510 --> 00:28:35,370
It's a tried and tested plan.

550
00:28:35,370 --> 00:28:37,230
It takes five men and a crane

551
00:28:37,230 --> 00:28:40,703
to heave the 300 kilogram hydrant into place.

552
00:28:43,940 --> 00:28:45,430
They're trying to connect the hydrant

553
00:28:45,430 --> 00:28:47,373
to an older section of branch pipe.

554
00:28:50,510 --> 00:28:54,213
And however many ways they try, it doesn't fit.

555
00:28:55,640 --> 00:28:57,170
Being that you're trying to repair something

556
00:28:57,170 --> 00:29:02,170
that was installed between, say, 1900 and 1960s,

557
00:29:02,480 --> 00:29:04,170
it makes the job very challenging.

558
00:29:04,170 --> 00:29:06,640
May not know if the job's going to take one hour

559
00:29:06,640 --> 00:29:08,048
or two hours.

560
00:29:08,048 --> 00:29:10,465
(indistinct)

561
00:29:11,345 --> 00:29:12,960
Right now there is no space.

562
00:29:12,960 --> 00:29:16,074
We're gonna have to cut the existing hydrant branch back

563
00:29:16,074 --> 00:29:19,340
a little more towards the street

564
00:29:20,390 --> 00:29:21,890
to give us a little more room.

565
00:29:24,920 --> 00:29:27,320
The hydrant needs to fit perfectly.

566
00:29:28,360 --> 00:29:29,590
A centimeter out

567
00:29:29,590 --> 00:29:32,020
and it will leak valuable water and pressure

568
00:29:32,020 --> 00:29:34,480
needed in the event of a fire.

569
00:29:34,480 --> 00:29:37,420
The team need to shave off some of the existing iron pipe

570
00:29:37,420 --> 00:29:39,360
to get it to the right size.

571
00:29:39,360 --> 00:29:41,580
At times it can be frustrating,

572
00:29:41,580 --> 00:29:44,180
especially if you're working in any kind of weather.

573
00:29:45,150 --> 00:29:46,860
But today, right now, it's a nice day.

574
00:29:46,860 --> 00:29:48,540
So it's just part of the game.

575
00:29:48,540 --> 00:29:49,800
You want everything to run smoothly

576
00:29:49,800 --> 00:29:52,500
but you expect little problems to go little by little.

577
00:29:53,490 --> 00:29:55,780
Try to get past all the bumps in the road.

578
00:29:55,780 --> 00:29:57,630
Not knowing what they're going to find

579
00:29:57,630 --> 00:29:59,320
every time they dig up the road

580
00:29:59,320 --> 00:30:02,490
is part of the job for John and his team.

581
00:30:02,490 --> 00:30:03,950
Each job is much different

582
00:30:03,950 --> 00:30:05,210
which makes it very interesting,

583
00:30:05,210 --> 00:30:06,560
each day to day job.

584
00:30:06,560 --> 00:30:08,530
At the end of the day, the jobs all get completed.

585
00:30:08,530 --> 00:30:09,700
All the guys come in,

586
00:30:09,700 --> 00:30:12,446
come into work safe and then go home safe.

587
00:30:12,446 --> 00:30:15,420
The branch pipe sits right next to a network

588
00:30:15,420 --> 00:30:17,193
of vital city services.

589
00:30:18,930 --> 00:30:22,630
The team must be careful not to puncture gas, water,

590
00:30:22,630 --> 00:30:25,380
telephone and internet lines.

591
00:30:25,380 --> 00:30:27,390
There's a lot of utilities in the way.

592
00:30:27,390 --> 00:30:30,380
Steam means and electric lines,

593
00:30:30,380 --> 00:30:32,270
oil and static lines.

594
00:30:32,270 --> 00:30:34,953
So it's much harder to repair the hydrants.

595
00:30:39,300 --> 00:30:42,020
Finally the pipe is down to size

596
00:30:42,020 --> 00:30:44,373
and the workers try the installation again,

597
00:30:46,630 --> 00:30:48,053
this time it works.

598
00:30:52,300 --> 00:30:55,060
But the job isn't quite over.

599
00:30:55,060 --> 00:30:57,890
The team must check all valves are tightened securely

600
00:30:57,890 --> 00:31:00,670
to avoid any valuable water seeping out

601
00:31:00,670 --> 00:31:03,763
and that the hydrant drains its own water correctly.

602
00:31:05,470 --> 00:31:07,515
The last step in installing a hydrant

603
00:31:07,515 --> 00:31:11,533
is making sure that the gasket and the retaining gland

604
00:31:11,533 --> 00:31:13,750
and the bolts are tight

605
00:31:13,750 --> 00:31:15,863
and you have the backing in the back of the hydrant

606
00:31:15,863 --> 00:31:17,530
so when you open it up,

607
00:31:17,530 --> 00:31:19,840
any pressure against the hydrant, it's fine.

608
00:31:19,840 --> 00:31:22,740
And you open it up to make sure it's running fine as well.

609
00:31:23,640 --> 00:31:25,600
Once the final checks are made,

610
00:31:25,600 --> 00:31:28,783
the surface area is restored with a layer of concrete.

611
00:31:31,506 --> 00:31:33,030
But they take for granted

612
00:31:33,030 --> 00:31:36,173
the work that goes behind the hydrant to keep it working.

613
00:31:37,090 --> 00:31:39,420
This hydrant is now ready for action,

614
00:31:39,420 --> 00:31:42,603
along with the other 110,000 in the city.

615
00:31:44,610 --> 00:31:46,500
It's been a challenging day for the team

616
00:31:46,500 --> 00:31:48,640
as they continue to keep New York

617
00:31:48,640 --> 00:31:50,333
armed against the flames.

618
00:31:53,357 --> 00:31:56,640
Moving water in and out of our cities

619
00:31:56,640 --> 00:31:59,180
is vital to our survival.

620
00:31:59,180 --> 00:32:01,270
Protecting and maintaining the structures

621
00:32:01,270 --> 00:32:03,933
that make this possible is a massive challenge.

622
00:32:07,100 --> 00:32:10,120
In San Francisco, the threat to its water infrastructure

623
00:32:10,120 --> 00:32:11,203
is much greater.

624
00:32:14,140 --> 00:32:15,730
In the next 20 years,

625
00:32:15,730 --> 00:32:19,240
the chance of an earthquake of 6.0 magnitude or higher

626
00:32:19,240 --> 00:32:22,923
hitting the area is as high as 60%.

627
00:32:25,410 --> 00:32:27,230
To avoid complete collapse,

628
00:32:27,230 --> 00:32:30,200
the city is defending one of its oldest structures,

629
00:32:30,200 --> 00:32:33,343
its sewer system, against the next big one.

630
00:32:37,150 --> 00:32:40,170
Today, veterans sewer inspectors, Lorenzo Hale

631
00:32:40,170 --> 00:32:43,220
and Fred Gonzalez are assessing a section of the sewer

632
00:32:43,220 --> 00:32:44,713
for structural damage.

633
00:32:46,450 --> 00:32:48,410
But before their descent, they must check

634
00:32:48,410 --> 00:32:52,600
for a dangerous occupational hazard, methane gas.

635
00:32:52,600 --> 00:32:54,855
We're about to put the gas meter

636
00:32:54,855 --> 00:32:59,741
hose inside the pit hole here just to test the atmosphere

637
00:32:59,741 --> 00:33:02,880
for any toxic gas or any methane,

638
00:33:02,880 --> 00:33:06,430
cause any little spark, if it's methane gas,

639
00:33:06,430 --> 00:33:07,793
could cause an explosion.

640
00:33:10,170 --> 00:33:11,980
The guys have the go-ahead

641
00:33:11,980 --> 00:33:13,230
but for their own safety,

642
00:33:13,230 --> 00:33:15,250
they have just one hour underground

643
00:33:15,250 --> 00:33:16,903
before they must resurface.

644
00:33:18,880 --> 00:33:22,560
San Francisco has one of the oldest sewers in the US.

645
00:33:22,560 --> 00:33:24,410
Originally built for a population

646
00:33:24,410 --> 00:33:27,160
of approximately 50,000 people,

647
00:33:27,160 --> 00:33:31,393
it's now a wastewater network for a city 16 times that size.

648
00:33:33,550 --> 00:33:36,910
It spans a staggering 1500 kilometers

649
00:33:36,910 --> 00:33:39,230
and can carry over one billion liters

650
00:33:39,230 --> 00:33:41,083
of city wastewater a day.

651
00:33:45,370 --> 00:33:48,060
The stress this puts on older sections of the network

652
00:33:48,060 --> 00:33:49,993
weakens its structure considerably.

653
00:33:51,660 --> 00:33:55,033
And it's Fred Gonzalez's job to protect it from collapse.

654
00:33:56,710 --> 00:33:57,890
99% Of the people

655
00:33:57,890 --> 00:34:00,590
probably don't even realize what's underneath the city.

656
00:34:00,590 --> 00:34:02,510
Until they have a problem,

657
00:34:02,510 --> 00:34:05,340
nobody really cares or understands

658
00:34:05,340 --> 00:34:06,840
what goes on under the ground.

659
00:34:07,990 --> 00:34:10,763
Their workspace is cramped, hot and dark.

660
00:34:12,060 --> 00:34:14,030
What we look for in this joint

661
00:34:14,030 --> 00:34:17,380
is any sand coming through

662
00:34:17,380 --> 00:34:20,253
or any kind of infiltration of water.

663
00:34:21,580 --> 00:34:23,490
Sand coming through a joint in the tunnel

664
00:34:23,490 --> 00:34:26,520
indicates a weakness that in the event of an earthquake

665
00:34:26,520 --> 00:34:28,203
could cause a total collapse.

666
00:34:29,710 --> 00:34:32,163
What happens is if sand starts coming through,

667
00:34:34,040 --> 00:34:37,630
there's no sand between this and the street.

668
00:34:37,630 --> 00:34:40,070
If enough sand washes away and a bus drives over it,

669
00:34:40,070 --> 00:34:42,020
the bus will actually fall into a hole.

670
00:34:43,140 --> 00:34:45,100
This joint is looking good for now,

671
00:34:45,100 --> 00:34:47,370
but a section of the wall further along the tunnel

672
00:34:47,370 --> 00:34:48,813
is cause for concern.

673
00:34:50,390 --> 00:34:53,240
The wall has been damaged during the winter rainy season

674
00:34:53,240 --> 00:34:55,653
when these tunnels run at full capacity.

675
00:34:56,610 --> 00:35:01,180
If you look right here, all these here is signs.

676
00:35:01,180 --> 00:35:03,733
At one time, the water level was this high,

677
00:35:04,850 --> 00:35:05,683
up to here.

678
00:35:06,970 --> 00:35:09,720
All these are all remnants of toilet paper

679
00:35:09,720 --> 00:35:11,600
and stuff that sticks to the wall.

680
00:35:11,600 --> 00:35:15,450
So when it rains, this runs full capacity almost.

681
00:35:15,450 --> 00:35:18,030
This sewer collects more than 300 million

682
00:35:18,030 --> 00:35:20,710
liters of wastewater a day,

683
00:35:20,710 --> 00:35:24,633
enough water to fill 120 Olympic size swimming pools.

684
00:35:25,550 --> 00:35:27,140
But when it rains heavily,

685
00:35:27,140 --> 00:35:29,623
it can be six times that amount of water.

686
00:35:30,680 --> 00:35:32,170
After every rainy season,

687
00:35:32,170 --> 00:35:34,520
we've got to really inspect these big sewers

688
00:35:34,520 --> 00:35:37,000
because that's when a lot of damage is being done

689
00:35:37,000 --> 00:35:39,858
which is gonna just cause big problems later.

690
00:35:39,858 --> 00:35:42,525
(tension music)

691
00:35:45,340 --> 00:35:47,850
Structural weaknesses in any part of the sewer

692
00:35:47,850 --> 00:35:49,603
must be dealt with straight away.

693
00:35:52,930 --> 00:35:56,440
Just marking the wall of this mine to be plastered.

694
00:35:57,410 --> 00:35:59,790
Lorenzo and Fred have reached their time limit

695
00:35:59,790 --> 00:36:01,730
and climb up to fresher air,

696
00:36:01,730 --> 00:36:04,200
but the job isn't quite finished.

697
00:36:04,200 --> 00:36:05,870
A team of plasterers is on its way

698
00:36:05,870 --> 00:36:08,003
to carry out the emergency repair.

699
00:36:11,170 --> 00:36:13,320
Strengthening this small section of sewer

700
00:36:13,320 --> 00:36:14,363
looks simple enough.

701
00:36:15,260 --> 00:36:17,050
But like Lorenzo and Fred,

702
00:36:17,050 --> 00:36:19,180
this team has a short window of time

703
00:36:19,180 --> 00:36:21,680
in which to carry out their work.

704
00:36:21,680 --> 00:36:25,140
Potentially, toxic gases and dark and damp conditions

705
00:36:25,140 --> 00:36:28,870
mean workers can't stay underground for more than an hour.

706
00:36:28,870 --> 00:36:31,560
This constant cycle of inspection and repair

707
00:36:31,560 --> 00:36:35,343
is the only way to keep San Francisco sewage structure safe.

708
00:36:36,560 --> 00:36:39,820
These aren't the sewer's only hidden heroes.

709
00:36:39,820 --> 00:36:42,270
Across the city, another rapid response team

710
00:36:42,270 --> 00:36:44,163
has received a call out.

711
00:36:44,163 --> 00:36:46,746
(upbeat music)

712
00:36:48,250 --> 00:36:51,477
{\an8}People might wash a lotta grease down the drain

713
00:36:51,477 --> 00:36:54,090
{\an8}and over a period of time it blocks the drain.

714
00:36:54,090 --> 00:36:55,740
Or they might

715
00:36:55,740 --> 00:36:57,423
flush too much toilet paper.

716
00:36:58,400 --> 00:36:59,233
There's a blockage

717
00:36:59,233 --> 00:37:00,870
in one of the smaller sewer pipes

718
00:37:00,870 --> 00:37:02,520
that connects the main drain,

719
00:37:02,520 --> 00:37:05,480
causing raw sewage to leak onto the streets.

720
00:37:05,480 --> 00:37:08,070
Veteran service engineer, Jose Ledesma,

721
00:37:08,070 --> 00:37:10,720
is proud of his part in keeping sewage flowing

722
00:37:10,720 --> 00:37:11,670
under the city.

723
00:37:11,670 --> 00:37:13,360
I've been working for this sewer word department

724
00:37:13,360 --> 00:37:15,000
for 16 years

725
00:37:15,000 --> 00:37:19,720
and I've been doing this kind of work for 30, 35 years now.

726
00:37:19,720 --> 00:37:22,190
And I'm impressed with what San Francisco has got.

727
00:37:22,190 --> 00:37:23,220
It's got good equipment,

728
00:37:23,220 --> 00:37:26,620
good tools for the sewer problems that we encounter.

729
00:37:26,620 --> 00:37:29,150
And today is no different.

730
00:37:29,150 --> 00:37:31,080
We're responding to an emergency.

731
00:37:31,080 --> 00:37:35,210
It's actually called a side service emergency backup.

732
00:37:35,210 --> 00:37:36,890
What it's doing, it's overflowing.

733
00:37:36,890 --> 00:37:38,713
It's not going out to the main.

734
00:37:40,110 --> 00:37:41,430
But the size of the pipe

735
00:37:41,430 --> 00:37:44,610
means that Jose can't go down to fix it.

736
00:37:44,610 --> 00:37:47,600
Instead, it's a job for Betsy.

737
00:37:47,600 --> 00:37:48,433
This is it.

738
00:37:48,433 --> 00:37:51,630
This is the one that gets all the work done, right here.

739
00:37:51,630 --> 00:37:53,840
Betsy is a 60 centimeter long

740
00:37:53,840 --> 00:37:57,510
stainless steel explosion-proof video camera

741
00:37:57,510 --> 00:38:00,570
that can get to places humans can't.

742
00:38:00,570 --> 00:38:03,150
On this job, Jose and Warren Best

743
00:38:03,150 --> 00:38:06,400
are hoping she can show them what the mystery blockage is.

744
00:38:06,400 --> 00:38:07,550
It's a tool.

745
00:38:07,550 --> 00:38:09,280
You gotta treat it like part,

746
00:38:09,280 --> 00:38:10,250
part of your job.

747
00:38:10,250 --> 00:38:13,120
Without this here, you can't do nothing.

748
00:38:13,120 --> 00:38:17,450
We ain't gonna have no results on what the problem is.

749
00:38:17,450 --> 00:38:20,543
Betsy's always gonna get the job done.

750
00:38:24,950 --> 00:38:26,400
From the back of the van,

751
00:38:26,400 --> 00:38:29,730
Warren controls Betsy as she travels down into the depths

752
00:38:29,730 --> 00:38:31,090
of the sewer.

753
00:38:31,090 --> 00:38:33,000
We need to pan and tilt, basically,

754
00:38:33,000 --> 00:38:35,870
to see 360 degrees of the pipe.

755
00:38:35,870 --> 00:38:40,010
Any defects that we might have, you know, in the pipe.

756
00:38:40,010 --> 00:38:42,930
All right, right here I'mma increase the speed.

757
00:38:42,930 --> 00:38:44,770
15 meters into her search

758
00:38:44,770 --> 00:38:47,053
and Betsy comes across the problem area.

759
00:38:49,100 --> 00:38:51,500
A large amount of grease from a nearby restaurant

760
00:38:51,500 --> 00:38:52,803
has built up in the pipe.

761
00:38:56,370 --> 00:38:59,820
It needs to be removed and it's Don's job to dislodge it

762
00:38:59,820 --> 00:39:03,270
with a high pressure hose and an industrial solvent capable

763
00:39:03,270 --> 00:39:05,500
of breaking down the grease.

764
00:39:05,500 --> 00:39:09,310
But the cause of the blockage is the usual offending items.

765
00:39:09,310 --> 00:39:11,520
Paper towels are bad.

766
00:39:11,520 --> 00:39:13,320
Diapers too. They don't break down.

767
00:39:13,320 --> 00:39:14,960
Paper towels and diapers

768
00:39:14,960 --> 00:39:16,600
get absorbed, like they could splash,

769
00:39:16,600 --> 00:39:19,280
blow up like 10 times of the volume.

770
00:39:21,440 --> 00:39:24,520
The jets works the blockage free.

771
00:39:24,520 --> 00:39:27,583
It's another battle won for the emergency team.

772
00:39:30,600 --> 00:39:32,760
But maintenance alone is not enough

773
00:39:32,760 --> 00:39:35,810
to keep a city's sewage system working.

774
00:39:35,810 --> 00:39:37,500
In downtown San Francisco,

775
00:39:37,500 --> 00:39:40,360
critical construction work is being carried out

776
00:39:40,360 --> 00:39:43,533
to protect a main wastewater pipe from collapse.

777
00:39:44,440 --> 00:39:46,190
The north shore force main,

778
00:39:46,190 --> 00:39:48,980
a pressurized pipe over two kilometers long

779
00:39:48,980 --> 00:39:52,460
moves untreated wastewater through the city

780
00:39:52,460 --> 00:39:56,190
but it has failed twice in the last five years.

781
00:39:56,190 --> 00:39:58,010
A bypass pipe is being built

782
00:39:58,010 --> 00:40:01,470
while vital repairs are carried out on the main pipe.

783
00:40:01,470 --> 00:40:03,187
This requires digging up the road

784
00:40:03,187 --> 00:40:05,830
right in the heart of the city.

785
00:40:05,830 --> 00:40:08,140
Construction in a city like San Francisco

786
00:40:08,140 --> 00:40:09,550
{\an8}is very challenging.

787
00:40:09,550 --> 00:40:12,210
{\an8}We're really webbing through a jungle of infrastructure

788
00:40:12,210 --> 00:40:14,283
{\an8}when we're trying to replace a soar line.

789
00:40:15,370 --> 00:40:16,980
The team make every effort

790
00:40:16,980 --> 00:40:20,023
to reduce the amount of road surface they need to dig up,

791
00:40:21,940 --> 00:40:23,680
but there's no escaping the dangers

792
00:40:23,680 --> 00:40:26,313
of working in this densely populated area.

793
00:40:28,540 --> 00:40:29,893
Where we are right now,

794
00:40:29,893 --> 00:40:31,600
it's the heart of the financial district.

795
00:40:31,600 --> 00:40:35,600
We have apartments, condominiums, tourists,

796
00:40:35,600 --> 00:40:38,350
visitors, workers, commuters.

797
00:40:38,350 --> 00:40:39,450
During any given day,

798
00:40:39,450 --> 00:40:41,670
the population of San Francisco doubles

799
00:40:41,670 --> 00:40:43,510
when the workforce enters the city.

800
00:40:43,510 --> 00:40:45,670
So we have to maintain that support.

801
00:40:45,670 --> 00:40:47,390
Despite these challenges,

802
00:40:47,390 --> 00:40:49,840
round the clock maintenance and new construction

803
00:40:49,840 --> 00:40:52,840
play a vital part in keeping the city's wastewater

804
00:40:52,840 --> 00:40:54,113
flowing out safely.

805
00:40:55,380 --> 00:40:57,710
But it's only half the battle.

806
00:40:57,710 --> 00:41:01,063
If left untreated, wastewater can spread disease.

807
00:41:02,550 --> 00:41:06,040
The average city dweller uses approximately 200 liters

808
00:41:06,040 --> 00:41:07,350
of water a day,

809
00:41:07,350 --> 00:41:08,640
flushing the toilet,

810
00:41:08,640 --> 00:41:11,123
taking a shower or doing the washing up.

811
00:41:12,910 --> 00:41:17,210
In Stockholm, over 350 million liters go down the plug hole

812
00:41:17,210 --> 00:41:18,643
on a daily basis.

813
00:41:21,000 --> 00:41:22,393
And it ends up here.

814
00:41:24,920 --> 00:41:27,405
This is Henriksdal,

815
00:41:27,405 --> 00:41:30,320
one of the largest underground wastewater treatment plants

816
00:41:30,320 --> 00:41:31,183
in the world.

817
00:41:33,231 --> 00:41:35,510
It's so vast, operating technician Dennis Goffin

818
00:41:35,510 --> 00:41:37,983
depends on his scooter to get around the plant.

819
00:41:38,940 --> 00:41:40,850
Its about 20 kilometers of tunnels,

820
00:41:40,850 --> 00:41:45,160
300,000 square meters of area.

821
00:41:45,160 --> 00:41:46,410
Seven digesters,

822
00:41:46,410 --> 00:41:49,280
about 30 tanks.

823
00:41:49,280 --> 00:41:50,570
It's a big place.

824
00:41:50,570 --> 00:41:52,680
One second you're sitting here in front of a computer screen

825
00:41:52,680 --> 00:41:54,520
and the other second you're down in like

826
00:41:54,520 --> 00:41:56,570
one of the filthiest places in Stockholm.

827
00:41:57,890 --> 00:42:00,868
Dennis is one of a team of 28

828
00:42:00,868 --> 00:42:04,050
whose job it is to process millions of liters

829
00:42:04,050 --> 00:42:05,290
of wastewater a day

830
00:42:06,980 --> 00:42:10,500
disposed of by over 700,000 people.

831
00:42:10,500 --> 00:42:12,100
But after so long in the job,

832
00:42:12,100 --> 00:42:15,110
Dennis no longer thinks about where the waste has come from.

833
00:42:15,110 --> 00:42:17,480
I don't even think that it's people's waste anymore.

834
00:42:17,480 --> 00:42:20,730
I just think that it's just some dirty mess

835
00:42:20,730 --> 00:42:22,370
that has to be cleaned.

836
00:42:22,370 --> 00:42:25,923
You don't even consider that it comes from someone.

837
00:42:27,780 --> 00:42:31,270
Most impressively, 98% of the waste water

838
00:42:31,270 --> 00:42:33,270
that comes through Henriksdal

839
00:42:33,270 --> 00:42:36,843
goes back into the Baltic Sea, clean enough to swim in.

840
00:42:38,840 --> 00:42:40,660
Stockholm is islands and water.

841
00:42:40,660 --> 00:42:42,121
That's all it is.

842
00:42:42,121 --> 00:42:43,920
So we have to protect that environment.

843
00:42:43,920 --> 00:42:46,160
That's why it's important to keep this process going

844
00:42:46,160 --> 00:42:48,373
and keep it getting better each day.

845
00:42:49,810 --> 00:42:51,840
It's a mammoth task.

846
00:42:51,840 --> 00:42:53,420
In the plants control room,

847
00:42:53,420 --> 00:42:55,070
computers monitor the intake

848
00:42:55,070 --> 00:42:57,270
of thousands of liters per second,

849
00:42:57,270 --> 00:42:59,543
which varies based on the time of day.

850
00:43:00,380 --> 00:43:01,735
So here we can see that it fluctuates

851
00:43:01,735 --> 00:43:03,240
in the middle of the day.

852
00:43:03,240 --> 00:43:05,482
It gets us

853
00:43:05,482 --> 00:43:09,750
about 3000 and then at nighttime all the way down

854
00:43:09,750 --> 00:43:12,890
to only 1000, even below that sometimes.

855
00:43:12,890 --> 00:43:15,633
Waste rush hour is right now at 7:00 a.m.

856
00:43:17,810 --> 00:43:20,490
As Stockholm's residents all head to the bathroom,

857
00:43:20,490 --> 00:43:24,097
the plant can often run over full capacity.

858
00:43:24,097 --> 00:43:27,247
We can see that about 12,000 liters a second came in

859
00:43:27,247 --> 00:43:28,447
and that causes trouble.

860
00:43:29,530 --> 00:43:30,670
In just one hour,

861
00:43:30,670 --> 00:43:32,550
the plant is capable of ingesting over

862
00:43:32,550 --> 00:43:35,003
36 million liters of wastewater.

863
00:43:36,530 --> 00:43:38,330
And down in the depths of the mountain,

864
00:43:38,330 --> 00:43:41,330
Dennis' colleague process engineer Hannah Astfelt,

865
00:43:41,330 --> 00:43:43,170
is heading off to monitor the first stage

866
00:43:43,170 --> 00:43:44,570
of the cleaning process.

867
00:43:50,150 --> 00:43:52,020
Henriksdal has a surface area

868
00:43:52,020 --> 00:43:54,563
the size of over 30 football pitches.

869
00:43:57,450 --> 00:44:00,540
Like Dennis, the only way for Hannah to get around

870
00:44:00,540 --> 00:44:02,260
to complete her morning checks

871
00:44:02,260 --> 00:44:05,950
is to take the latest model of sewage plant transport.

872
00:44:05,950 --> 00:44:08,583
Everybody needs a bike or a moped to work here.

873
00:44:10,360 --> 00:44:13,050
This motorized trait is a definite upside

874
00:44:13,050 --> 00:44:16,820
to a job that sees Hannah exposed to thousands of liters

875
00:44:16,820 --> 00:44:18,793
of her fellow residents' waste.

876
00:44:20,190 --> 00:44:23,140
As we can see, there's a lot of debris from the humans.

877
00:44:23,140 --> 00:44:24,490
There's

878
00:44:24,490 --> 00:44:27,154
sanitary articles, condoms,

879
00:44:27,154 --> 00:44:30,050
food.

880
00:44:30,050 --> 00:44:32,034
Step screens extract any debris

881
00:44:32,034 --> 00:44:34,763
bigger than three millimeters from the water.

882
00:44:36,020 --> 00:44:38,850
That includes 10 tons of earbuds,

883
00:44:38,850 --> 00:44:40,933
tampons and condoms a week.

884
00:44:42,780 --> 00:44:45,470
These items could cause devastating damage

885
00:44:45,470 --> 00:44:48,373
to machinery and bring the plant to a halt.

886
00:44:49,240 --> 00:44:50,840
I think people sort of think

887
00:44:50,840 --> 00:44:52,770
that they can throw anything into toilet,

888
00:44:52,770 --> 00:44:54,260
but for us it's a big problem

889
00:44:54,260 --> 00:44:56,950
because these material

890
00:44:57,930 --> 00:44:59,840
creates a great damage

891
00:44:59,840 --> 00:45:02,830
if they continue for the process.

892
00:45:02,830 --> 00:45:04,050
But the items aren't limited

893
00:45:04,050 --> 00:45:05,623
to what goes down the toilet.

894
00:45:07,160 --> 00:45:10,400
The city's drains also empty into this facility

895
00:45:10,400 --> 00:45:12,483
with some surprising results.

896
00:45:14,010 --> 00:45:16,730
A bicycle, a canoe,

897
00:45:16,730 --> 00:45:20,060
and we have seen driving license

898
00:45:20,060 --> 00:45:21,780
and even teeth from people.

899
00:45:21,780 --> 00:45:26,193
So I don't think we can be any more shocked.

900
00:45:29,340 --> 00:45:31,020
Here at the sediment tanks,

901
00:45:31,020 --> 00:45:33,220
gravity does the work.

902
00:45:33,220 --> 00:45:36,100
Solid matter or sludge sinks to the bottom

903
00:45:36,100 --> 00:45:38,720
whilst cleaner water flows from the top.

904
00:45:38,720 --> 00:45:41,380
But it doesn't always go to plan.

905
00:45:41,380 --> 00:45:44,240
Today, Dennis and Hannah have noticed something strange

906
00:45:44,240 --> 00:45:46,160
during their daily inspection,

907
00:45:46,160 --> 00:45:48,580
an abnormal buildup of sludge.

908
00:45:48,580 --> 00:45:51,263
We're seeing sludge that should be sinking,

909
00:45:51,263 --> 00:45:53,866
but for one reason or another

910
00:45:53,866 --> 00:45:56,120
some bad bacteria is formed

911
00:45:56,120 --> 00:45:57,580
and not been taken care of

912
00:45:57,580 --> 00:46:00,120
in the biological cleaning process

913
00:46:00,120 --> 00:46:02,190
which means it comes down to this process

914
00:46:02,190 --> 00:46:07,190
and creates these carpets which causes it to float up.

915
00:46:07,200 --> 00:46:09,140
With epic volumes of wastewater

916
00:46:09,140 --> 00:46:12,100
to process every day, Hannah and Dennis can't afford

917
00:46:12,100 --> 00:46:15,140
to let one defect in the chain affect the next.

918
00:46:15,140 --> 00:46:17,260
However small a problem, it could escalate

919
00:46:17,260 --> 00:46:18,700
in a matter of minutes

920
00:46:18,700 --> 00:46:21,650
and have a detrimental effect on the quality of clean water

921
00:46:21,650 --> 00:46:22,800
going out of the plant.

922
00:46:23,640 --> 00:46:25,180
The team leave nothing to chance

923
00:46:25,180 --> 00:46:27,110
and draft in another young member

924
00:46:27,110 --> 00:46:30,010
who gives the sludge a helping hand to sink to the bottom.

925
00:46:30,983 --> 00:46:33,070
This is the regular everyday business,

926
00:46:33,070 --> 00:46:35,933
to just go through the entire process.

927
00:46:36,890 --> 00:46:38,050
Does it smell bad?

928
00:46:38,050 --> 00:46:40,220
That means it's probably a problem somewhere.

929
00:46:40,220 --> 00:46:42,183
Does it look bad?

930
00:46:43,960 --> 00:46:46,300
My girlfriend doesn't know what my job entails.

931
00:46:46,300 --> 00:46:48,090
No one knows what I work with.

932
00:46:48,090 --> 00:46:50,543
People don't even know how big this place is.

933
00:46:51,860 --> 00:46:53,280
One of the final processes

934
00:46:53,280 --> 00:46:55,240
known as the biological stage

935
00:46:55,240 --> 00:46:58,563
is critical to making this water clean enough to swim in.

936
00:46:59,480 --> 00:47:01,163
And it's completely invisible.

937
00:47:03,560 --> 00:47:05,870
Good bacteria devours the organic matter

938
00:47:05,870 --> 00:47:07,670
and nitrogen in the waste.

939
00:47:07,670 --> 00:47:10,473
And 24 hours later, the result is this,

940
00:47:12,030 --> 00:47:13,850
water in this jacuzzi style outflow

941
00:47:13,850 --> 00:47:16,230
is on its way back to the Baltic Sea

942
00:47:16,230 --> 00:47:19,643
at an average speed of 2000 liters per second.

943
00:47:21,790 --> 00:47:24,090
Our job is to clean the water

944
00:47:24,090 --> 00:47:25,740
from this dirty mess that we saw

945
00:47:25,740 --> 00:47:28,730
into water that we can actually put back into the Baltic Sea

946
00:47:28,730 --> 00:47:29,880
with a clear conscience.

947
00:47:29,880 --> 00:47:32,291
You don't have to go back that far

948
00:47:32,291 --> 00:47:35,610
to see a time where you could not swim in Stockholm.

949
00:47:35,610 --> 00:47:37,760
It was actually illegal to swim

950
00:47:37,760 --> 00:47:39,960
anywhere in the city of Stockholm

951
00:47:39,960 --> 00:47:41,520
and now you can swim anywhere.

952
00:47:41,520 --> 00:47:43,120
You can ask anyone in Stockholm.

953
00:47:47,690 --> 00:47:49,470
In most water treatment plants,

954
00:47:49,470 --> 00:47:51,810
this is where the story ends,

955
00:47:51,810 --> 00:47:54,930
but Henriksdal is one of the few plants around the world

956
00:47:54,930 --> 00:47:57,913
reducing the amount of water waste even further.

957
00:48:00,050 --> 00:48:02,720
While some plants discard their sludge,

958
00:48:02,720 --> 00:48:04,230
Dennis and his team consider it

959
00:48:04,230 --> 00:48:06,860
one of their most prized products.

960
00:48:06,860 --> 00:48:09,700
Well here we mix the primary sludge

961
00:48:09,700 --> 00:48:11,540
with the secondary sludge,

962
00:48:11,540 --> 00:48:14,890
with the organic matter that comes into our organic station.

963
00:48:14,890 --> 00:48:16,350
This all gets mixed together.

964
00:48:16,350 --> 00:48:18,010
And with these pumps,

965
00:48:18,010 --> 00:48:21,853
pumps into the digesters to begin creating biogas.

966
00:48:24,140 --> 00:48:26,280
Our advantage is that we are so big,

967
00:48:26,280 --> 00:48:28,268
that we get so much in,

968
00:48:28,268 --> 00:48:29,240
that we can actually do this stuff,

969
00:48:29,240 --> 00:48:31,573
that we can actually make this much gas.

970
00:48:32,980 --> 00:48:34,610
After leaving Henriksdal,

971
00:48:34,610 --> 00:48:37,240
waste matter goes through a further refining stage

972
00:48:37,240 --> 00:48:40,973
before arriving at Keolis bus depot in the form of biogas.

973
00:48:41,960 --> 00:48:44,470
Here, a fleet of about 120 buses

974
00:48:44,470 --> 00:48:47,140
take minutes to fuel after a 22 hour shift

975
00:48:47,140 --> 00:48:49,340
on the city's roads.

976
00:48:49,340 --> 00:48:51,330
But the difference is that this biogas

977
00:48:51,330 --> 00:48:54,040
is entirely renewable and much less polluting

978
00:48:54,040 --> 00:48:56,290
than ethanol or diesel.

979
00:48:56,290 --> 00:48:59,610
It's the way forward for technical advisor, Eric Norden.

980
00:48:59,610 --> 00:49:03,210
I'm proud to say that our fleet here runs on biogas.

981
00:49:03,210 --> 00:49:07,920
I would like more companies to go with it because it's good.

982
00:49:07,920 --> 00:49:09,163
It's really good.

983
00:49:10,810 --> 00:49:14,560
It's actually amazing that you can make fuel other ways.

984
00:49:14,560 --> 00:49:16,206
You know, people flush their toilets

985
00:49:16,206 --> 00:49:19,193
and it turns into fuel for cars and buses.

986
00:49:20,070 --> 00:49:21,730
Henriksdal turns a record

987
00:49:21,730 --> 00:49:25,270
one and three quarter trillion liters of wastewater a week

988
00:49:25,270 --> 00:49:27,930
back into clean water and biofuel,

989
00:49:27,930 --> 00:49:30,473
making this plant a model for the future.

990
00:49:32,657 --> 00:49:35,160
(lighthearted music)

991
00:49:35,160 --> 00:49:38,810
Cities around the world depend on the skill of engineers,

992
00:49:38,810 --> 00:49:41,750
scientists, inspectors and technicians

993
00:49:41,750 --> 00:49:43,423
{\an8}to keep our water flowing.

994
00:49:45,880 --> 00:49:48,660
{\an8}Without this hidden army working tirelessly

995
00:49:48,660 --> 00:49:49,950
{\an8}around the clock,

996
00:49:49,950 --> 00:49:54,090
{\an8}our survival, well-being, safety and prosperity

997
00:49:54,090 --> 00:49:55,903
{\an8}would be seriously at risk.