0:00:05 > 0:00:08This is Blue Peter, but mini!
0:00:08 > 0:00:12Expect epic adventures, mates, bakes, badges,
0:00:12 > 0:00:15pets, presenters, and your post.
0:00:15 > 0:00:18Coming up, things get yucky! You have been warned.
0:00:20 > 0:00:23London, home to over eight million people and growing.
0:00:25 > 0:00:27Producing millions of tonnes of waste that
0:00:27 > 0:00:31relies on a network of sewers built 150 years ago.
0:00:31 > 0:00:35And they're struggling to keep up with all that poo.
0:00:35 > 0:00:39Something had to be done, so, new super-sewers like this
0:00:39 > 0:00:41one are here to help take the extra waste away.
0:00:42 > 0:00:45This is newly built Lee Tunnel, and I'm one of the last
0:00:45 > 0:00:49people to come down here before it starts being used.
0:00:49 > 0:00:51At 80 metres below the surface,
0:00:51 > 0:00:53it's almost as deep as Big Ben is tall.
0:00:53 > 0:00:55BIG BEN CHIMES
0:00:55 > 0:00:58And it will be able to handle more than 16 million
0:00:58 > 0:01:01tonnes of sewage every year. That's a whole lot of poo.
0:01:01 > 0:01:05And down here there's only one way to travel. In style.
0:01:05 > 0:01:08This is the deepest tunnel ever built in London,
0:01:08 > 0:01:11and it stretches four miles that way.
0:01:11 > 0:01:13Go for it Ian!
0:01:14 > 0:01:16Woo!
0:01:21 > 0:01:25What's great is that it doesn't smell. Yet. It will smell.
0:01:26 > 0:01:30At the end of the tunnel is the pumping station where the waste will
0:01:30 > 0:01:33get transported back to the surface to be treated.
0:01:33 > 0:01:37It's also the place where you'll find Phil who helped construct the
0:01:37 > 0:01:41new sewer. So Phil, why is this new super-sewage system so important?
0:01:41 > 0:01:43Why does it need to be here?
0:01:43 > 0:01:45Well, in the 1850s when the Victorians built the sewage
0:01:45 > 0:01:48system, there was only about two million people in London.
0:01:48 > 0:01:50Now we're over eight million.
0:01:50 > 0:01:53We need somewhere for our additional sewage to go.
0:01:53 > 0:01:54Without the super-sewer,
0:01:54 > 0:01:57that additional sewage would flow into the Thames.
0:01:57 > 0:02:00And I guess that's what this pipe here does, isn't it?
0:02:00 > 0:02:03Yeah, this pipe takes it from the tunnel, all the way up
0:02:03 > 0:02:05to the top to be treated in the sewage treatment works.
0:02:05 > 0:02:08So is there anything that I can do to help on this massive project?
0:02:08 > 0:02:10Well we've got a few more of these bolts to tighten up,
0:02:10 > 0:02:13so if we go over there, we'll get to it.
0:02:13 > 0:02:14Great! Let's do it!
0:02:14 > 0:02:17The bolts I'm about to tighten seal the massive pipes that
0:02:17 > 0:02:20transport the waste back to the surface.
0:02:20 > 0:02:24- So I'd want to put the spanner on the bottom, here.- Yep.
0:02:24 > 0:02:27Luckily for me, there's a special machine that does all the hard work.
0:02:27 > 0:02:31- And if you push that machine in, push that button at the top.- OK.
0:02:33 > 0:02:37- Hear it click-in there.- Oh, it's tight enough! It's happy, isn't it!
0:02:37 > 0:02:39- No leaks here.- No leaks here!
0:02:39 > 0:02:42London, thanks to me you're safe from leaky poo now.
0:02:42 > 0:02:44FLUSHING NOISE
0:02:44 > 0:02:47Bolts tightened, and the Lee Tunnel is almost ready to be opened.
0:02:47 > 0:02:49Do you know what?
0:02:49 > 0:02:51I'm just really glad I got sent down a nice, clean sewer,
0:02:51 > 0:02:53and I didn't have to go in a stinky Victorian one.
0:02:53 > 0:02:55- OFF-SCREEN:- Um... Ahem...
0:02:55 > 0:02:57- Wait, the films not over yet, is it? - Eh... No.
0:02:57 > 0:03:00- I'm going to have to go in a smelly sewer, aren't I?- Yeah...
0:03:00 > 0:03:02TOILET FLUSHES
0:03:02 > 0:03:07Yup, that's certainly stinky. When I say stinky, I mean it.
0:03:07 > 0:03:09It absolutely hums down here...
0:03:11 > 0:03:15This sewer runs beneath one of London's busiest areas,
0:03:15 > 0:03:19and it was designed 150 years ago by this man.
0:03:19 > 0:03:21Joseph Bazalgette... Nice 'tache, Baz...
0:03:21 > 0:03:22To take away the city's waste.
0:03:22 > 0:03:26Before the sewer network was built, raw sewage went straight into
0:03:26 > 0:03:30the streets and rivers, spreading disease and making the city smell.
0:03:30 > 0:03:33In 1858, it got so bad that the era became known as the
0:03:33 > 0:03:36"Great Stink of London". Poo-eee!
0:03:36 > 0:03:39But nowadays along with the increased population,
0:03:39 > 0:03:42there's another problem causing a strain on the sewers.
0:03:42 > 0:03:45Because lurking in the shadows are "fatbergs".
0:03:46 > 0:03:48SHE SCREAMS
0:03:50 > 0:03:51Mixed in with all this poo,
0:03:51 > 0:03:55the fatbergs are huge lumps of congealed grease and oil,
0:03:55 > 0:03:58combined with food and rubbish that can be hundreds of metres long.
0:03:58 > 0:04:01Yuck. And today, I'm taking the fatbergs on.
0:04:01 > 0:04:02Gary, it's good to meet you,
0:04:02 > 0:04:05but I would have preferred not to meet you down a sewer.
0:04:05 > 0:04:06What are we going to be doing today?
0:04:06 > 0:04:09Today we're going to be clearing a bit of fat off the walls.
0:04:09 > 0:04:10I brought you a little present as well.
0:04:10 > 0:04:13- So you can give me a hand doing it. - Brilliant...A pooey shovel.
0:04:13 > 0:04:18- OK, so where do we start here?- Well, you just go down like that, tug it.
0:04:18 > 0:04:21I think I can manage that. There's just one small problem.
0:04:21 > 0:04:26Sorry, this smell is so bad. This is horrible!
0:04:26 > 0:04:27GARY LAUGHS
0:04:27 > 0:04:30- Do you know what your best thing is to do?- Yeah?
0:04:30 > 0:04:32Think of somewhere hot and nice. It totally goes out your mind.
0:04:32 > 0:04:35- I don't know about that.- It will, trust me.- Woo, come on!
0:04:35 > 0:04:38Let the shovelling begin.
0:04:38 > 0:04:40Argh...
0:04:40 > 0:04:42There you go, Linds, look at that.
0:04:42 > 0:04:44What this is, is the fat is actually on the side of the walls,
0:04:44 > 0:04:46on top of the float.
0:04:46 > 0:04:48Oh, that is so deep!
0:04:48 > 0:04:49So, Gary, what SHOULD be down here?
0:04:49 > 0:04:51Only three things should be down in this sewer,
0:04:51 > 0:04:55- and that's pee, paper, and poo.- The three Ps.- The three Ps.
0:04:55 > 0:04:57- That's it, nothing else. - Nothing else!
0:04:57 > 0:05:01Anything else you put down your loo or your sink ends up here.
0:05:01 > 0:05:02Fatbergs also come at a price because
0:05:02 > 0:05:06they cost water companies millions of pounds to get rid of.
0:05:06 > 0:05:12THAT is what a fatberg looks like, and it absolutely stinks.
0:05:12 > 0:05:15- Can I put it down?- Yeah, just put it down over there...
0:05:19 > 0:05:21Ahh...Ew!
0:05:21 > 0:05:23You know what, that was SO smelly down there,
0:05:23 > 0:05:26but having seen what's down there, I now understand exactly why
0:05:26 > 0:05:28new super-sewers like Lee Tunnel are needed.
0:05:28 > 0:05:31Can I get out now?
0:05:31 > 0:05:33Thankfully, the new sewer will be sending
0:05:33 > 0:05:37millions of tonnes of waste to this treatment works to be filtered.
0:05:39 > 0:05:41After the sewage is treated, it ends up here,
0:05:41 > 0:05:44where it re-enters the river Thames as clean water.
0:05:44 > 0:05:48I can an smell something really pooey.
0:05:48 > 0:05:49I think it's me.
0:05:52 > 0:05:54Join in every Thursday on CBBC!