Big stink over tideway tunnel
A £2.2 billion super sewer is the only way to stop waste discharges into the Thames, Britain’s peak environment body claims.
By Elizabeth Pearson
- Rower against sewage, courtesy of UK Environment Agency 2009 -
The UK Environment Agency says plans to build a 20 mile long pipeline under the city will ease the pressure on London’s Victorian drains, greatly reducing the volume of waste discharged into the river.
The capital’s outdated drainage system currently pumps more than 32 million cubic metres of untreated waste into the Thames every year when pipes exceed capacity.
As little as 2mm of rain is enough to trigger an overflow.
Policy and External Relations Manager of the Thames Estuary Programme, Chris Burnham, admits the river has seen better days.
“The Thames has had a very chequered history. As recently as the early 60s, it was declared biologically dead. Prior to that, essentially streets all had sewage running through them into pipes- which ended up in the river. So we ended up with the Thames tributaries being sewers,” he said.
“The Bazalgette system is a fantastic system and still is the backbone of what we have today… [but] you’re starting now to see the impact of these combined sewage overflows more and problems related to sewage will occur.”
In addition to posing health risks to recreational river users, these discharges have had a detrimental impact upon the Thames’ ecosystems.
“Predominantly, you get an oxygen drop in the river. To break down all the organic material in the discharge, you need all the bacteria working away, using up oxygen out of the waterway,” Mr Burnham said.
“Essentially what we’ve seen now a number of times are fish kills because of these oxygen drops- it’s a situation which is going to get worse unless we do something really soon.”
- Thames fish kill, courtesy of Environment Agency 2004 -
Excess discharges from five major sewage works along the tidal Thames have only exacerbated the problem. More than 200 flounder fish died in the wake of a raw sewage discharge from the notorious Mogden Sewage Treatment works in Isleworth in 2007. In a statement, the company maintained it had no other choice.
“This legally consented discharge into the river took place following a very heavy downpour, which filled the storm tanks at Mogden, after which there was literally nowhere else for the storm sewage to go,” it said. “We very much regret the impact on the river, but this was not an accident.”
“Had it not gone into the river, the excess flows would have backed up into people’s homes nearby, and that wasn’t an option.”
Liberal Democrat Leader Mike Tuffrey told the London Assembly in 2009 that action must be taken sooner rather than later.
“The dumping of untreated sewage in the Thames is associated with the Victorian era but disgracefully it is still happening in the 21st century in one of the most developed capital cities in the world.”
“Such sewage is unsightly for everyone as well as damaging to marine life. However, the problems are most severe for users of the Thames who face bacteria and viruses,” he said.
- Fats at Combined Sewage overlow, courtesy of UK Environment Agency 2009 -
But Thames Water claims that despite this, the river is the cleanest it’s been in decades.
“The Thames is as clean today as it’s ever been since Victorian times, down largely to significant improvements in effluent treatment standards at Thames Water’s sewage works, which feed into the river,” said Senior Press Officer Simon Evans.
“This is perhaps best illustrated by the fact that 13 more species of fish now inhabit the tidal Thames in London than 20 years ago, when the water sector in England and Wales was privatised.”
But he admits there’s still work to be done.
“Despite vast improvements to the river, there remains a big problem: London’s sewerage system is Victorian, built in the 1850s and 60s by Sir Joseph Bazalgette following the Big Stink of 1858 when Parliament had to reconvene at Oxford because the stench from the Thames, then an open sewer and biologically dead, simply overwhelmed the Palace of Westminster.”
“One design feature of Bazalgette’s system was 57 combined sewer overflows (CSO), designed to spill into the river once in a blue moon in the event of severe rainfall. Nowadays CSOs that once went off very rarely go off once a week on average sometimes after as little as 2mm of rain. That means untreated sewage is ending up in the river on an increasingly frequent basis, not only from the sewer system but also from the five major sewage works along the tidal Thames, which struggle to cope with today’s heavy flows.”
“This can’t be right,” he added.
The Environment Agency has been working on a number of short term solutions to minimise the impact of sewage spills but without much success.
“At the moment we monitor the oxygen content- real time monitoring, and whenever we see that there is a significant drop in oxygen we contact Thames water and they send out what they call bubbles, which are essentially boats that pump oxygen down into the water to try and bring those oxygen levels up,” Mr Burnham explained.
“Last year they launched a couple of skimming vessels and that takes a lot of the floating sewage related debris out of the river but it’s just a sticking plaster really- short term solutions. The Tideway tunnels are a long term solution.”
The Thames Tideway Tunnels scheme would see twin mega sewers built under the river to contain and carry excess waste water east. Work has already begun on the shorter tunnel to move water from Abbey Mills to Beckton while construction of the large pipe, to convey storm water from Hammersmith to Battersea, isn’t due to commence until 2012.
But the Consumer Council of Water holds grave concerns about the scheme.
“The problem is that the big tunnel isn’t really a sewer, it’s a cesspool,” said Chairman of the London committee, David Bland. “The energy cost of building it plus the energy cost of pumping stuff in and pumping stuff out and keeping it clean- all that is going to absolutely astronomical.”
“It seems too simplistic and too costly. We should go back to the drawing board.”
- CSO discharge at Putney, courtesy of Environment Agency 2009 -
Thames Water is currently in the process of identifying potential construction sites in suburban London to dig access points for the super sewer but progress has been slow. The Consumer Council for Water believes alternate solutions should be further investigated before the government signs on the dotted line.
“We have been advocating that there should be a review of all alternatives. We would not expect the alternatives to be cheaper but they could probably be done on a large scale by a series of much smaller projects that could take into account localised problems as well as the main river,” Mr Bland said.
“Bazalgette had men in streets with water drums measuring rainfall. In recent years, it’s all been done by guess-timation, triangulation and computer modelling and so on. Therefore, it is much less reliable than measuring buckets in terms of data set. It is generally accepted- we don’t quibble to any great extent with the data, we just comment that they are not as precise as the data that Bazalgette had.”
New environmental directives from the European Union have placed further pressure on the British government to take action on the Thames but Bland says it’s only sparked widespread panic.
“The government is terrified of infraction proceedings from the EU, were offered the tideway tunnels solution and said ‘that’s it’ and wrote to Thames, saying ‘let’s get on with it’. The last thing the British government wants is to be paying a fine and their subservience to Brussels means they will do anything to try and stop themselves being fined,” he said.
The Consumer Council for Water predicts London could see price hikes of more than 10 percent per annum on their water bills to fund the tunnel scheme should it go ahead.
“The European Union and the directive making body do not expect water consumers to pay for major environmental schemes like this whereas the UK has no other way of charging this, except general taxation.”
“Putting [the cost] on water users is not what the EU legislation intends but it’s the way the cookie’s crumbled in the UK. Though water is not the most expensive commodity in life, if it doubles in price with no apparent change in service, there are going to be questions,” Mr Bland concluded.
Almost fifty percent of households with children in the capital’s inner boroughs register in the bottom quintile incomes. Many families would struggle to meet the estimated price hikes, especially in the current economic crisis.
“If we were back in the days of the industrial revolution, the government would just decide to spend the money necessary to do what was required,” Mr Bland said.
“We’re not in that position now. We’re in the position where, thanks to 40 years of incompetent government, we are effectively without resources and therefore the national budget just wouldn’t take it. It’s an example of British bureaucracy not working. We are a dysfunctional country and it’s really embarrassing,” he added.
“The escalation in the cost of the smaller tunnel has been well over doubling already and still the final cost obviously can’t be estimated. Therefore, while the figure for the big, big tunnel is just crazy and I was on television a fortnight ago saying five billion- by the time it’s been inflated, it can’t be less than five.”
The chairman maintains that the advisory council is keeping an open mind and considering all alternatives.
“We’ve never opposed the tunnel as such but we’ve raised questions,” he stated.
Consulting engineers have also raised concerns that should climate change continue on the current trajectory, this super sewer may not be big enough to cope with the volumes of rainwater forecast.
“There are very large audiences at public meetings of people who are deeply fed up with the idea that their local area is going to be disrupted by big digging machines and secondly, that this probably will not immediately resolve the problems,” Mr Bland said.
Hammersmith and Fulham Council has also voiced numerous concerns about the project. In an executive summary documenting its position, the Council claimed the tunnelling strategy was a “seriously flawed and short-sighted option that needs review” and would exert “major unexplored implications”.
“Specialists involved [in the scheme] have all acknowledged that tunnelling poses formidable challenges and unforeseeable problems that will be reflected in delays, disruptions and therefore increased costs,” it said.
“The requirement for accelerated delivery makes these risks even more pronounced in terms of the most expensive scheme becoming more expensive still.”
Construction of the main tunnel beneath the city would involve the digging of 6 main shafts on sites of two hectares in addition to up to five intermediate shafts, each occupying an area of up to six acres.
“In an area as precious and highly populated as London’s riverside the disruption that these developments will impose on Londoners and visitors to the Capital, over an estimated eight year period, will be devastating,” the council said.
New Civil Engineer and Professor of Urban Water at Sheffield University, Richard Ashley, told the council the tunnel proposal is simply a case of history repeating itself.
“They are repeating what Bazalgette did years ago- they are building the tunnel because the system cannot cope with the levels of storm water and of course, they’ll go and build a desalination plant because of water shortages. There is no joined up thinking,” he said.
Thames Water is continuing to scout for suitable construction sites in London’s western boroughs.
