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UTILITY WEEK | 8TH - 14TH JULY 2016 | 21 Operations & Assets Average annual household bills already include £13 for the tunnel and this will rise to no more than £25 a year, before inflation. 400 workers directly employed on the project. 25km Length of the tunnel when completed. 20m tonnes of untreated sewage the tunnel will prevent from discharging into the Thames each year. £4.2bn Construction cost of of the tunnel. £700m The tunnel secured a loan from the European Investment Bank – the largest ever for water investment. £1.1bn of the construction bill will be financed by Thames Water customers. £3.1bn will be funded by Bazalgette Tunnel. TIDEWAY IN NUMBERS The £4.2 billion Thames Tideway Tunnel is set to relieve some of the strain on London's Victorian sewerage system, which is creaking under the load put upon it by a continuously growing urban population. Last month, Thames Water invited me to marvel at a small section the subterranean sys- tem that has served our capital for more than a century. My entry point: Wick Lane, about a mile from the Olympic Stadium. What strikes you – once you've got into your single use overall, full-length leg waders, hard hat and single use emergency oxygen mask (known as a turtle) – is that you are essentially standing in an underground river. Thames Water's operations manager at the Wick Lane depot is Nick Fox. He is one of the flushers, as they are affectionately known, and says most people "expect to be wading through slurry". In fact, what we are standing in is 98 per cent water, most of it clean water from sinks, baths or showers. This explains why the smell I'd been preparing myself for is largely absent. Before our exploration along a short stretch of sewer begins, we are told to adopt the "flusher shuffle" so we don't trip on the so surface underfoot – created largely by the grit runoff from the capital's roads. Fiy metres from the ladder we descended, we pause. Fox indicates the hand-laid brickwork – most of which is about 150 years old – which is still in pristine condition. He also points out what look like boarded-up windows in the sewer tunnel. These were closed off in 2012 to prevent sewer overflows into the surrounding waterways before the Olympic Games. We shuffle onwards and enter a much larger sewer – at least 10m in diameter. Here, we see the beginnings of a fatberg. Wet wipes are clinging to chains and any exposed fittings, and are beginning to congeal and clump together. This is another reminder of the chal- lenges the water companies face. Our flusher guide also points out a set of cables running along the top of the tunnel. They are fibre optic cables. Fox says the new, high-tech data connections use the old Victo- rian networks because its quicker, cheaper and easier to fit them in the sewers than to dig up the roads. We turn to head towards our exit point, and pass through a slightly deeper stretch of water, which comes uncomfortably close to the top of my waders. Fox says that, although currently live, the flow into this stretch of sewer has been restricted – making it possible for this intrepid journalist to visit. He says the water would usually be running about 1.5m deep, and aer a short period of rainfall would be all but fully submerged. Hurrying for the exit as the grey clouds in the outside world gather, I can't help but appreciate the future importance of the supersewer, which will not only take some of the strain off Bazalgette's subterranean masterpiece, but also ease the worries of the next group heading down the drain. MB "What we are standing in is 98 per cent water, most of it clean water from sinks, baths or showers. This explains why the smell I'd been preparing myself for is largely absent" "Here, we see the beginnings of a fatberg. Wet wipes are clinging to chains and any exposed fittings, and are beginning to congeal and clump together" Mathew Beech heads down the drain to find out first hand the issues Thames faces, and why the Tideway Tunnel is required.