Super-sewage tunnel approved for London

A project to build an extra large sewer which will run for some 16 miles (25km) beneath London and the River Thames, was given the official go ahead this month.

The Thames Tideway Scheme is a tunnel intended to provide storage and a conveyance route for raw sewage and rain water discharges. The current solution still very much relies upon the Victorian sewer structure; however at times this ageing structure gets overloaded and results in substantial sewage overflows into the River Thames.

It is a wonder of Victorian engineering (as we discussed in last month’s newsletter) that the system implemented predominantly by the Victorians actually is still largely intact and taking the majority of the sewage of London in the 21st Century, some 150 years after construction. But the system is undoubtedly outdated and struggling to cope with the fast growing London population.

Thames Water estimates that the current system overflows on a weekly basis and is responsible for flushing 39 million tonnes of raw sewage into the Thames each year. Some 55 million tonnes of sewage poured into the Thames in 2013 alone, as heavy rainfall caused an excessive number of overflows.

The route, proposed by Thames Water as a solution, involves the construction of the Thames Tideway Tunnel which will run from Acton Storm Tanks in the west of London all the way through to Abbey Mills pumping station in the east.

The main tunnel, which will have an internal diameter of 24 ft and will be running approximately 100ft or more below the surface, is envisaged to prevent much of the unwanted overflow, consequently improving the quality of the water in the Thames.

Ministers say the planned tunnel is practically the only viable solution to reduce the water pollution.  Due to current EU guidelines, failure by the UK to reduce or remove the current level of water pollution could see them responsible for fines of up to £100million a year.

Liz Trust, the Environment Secretary and Eric Pickles, the Community Secretary, have effectively approved the construction. The earliest construction is likely to commence is 2015 although it is more likely to be 2016 when things properly get under way.

The project is likely to create some disturbance at individual locations and will also need to be paid for by the water rates of the majority of those in the Thames Water area. Occupants in London and the South East are likely to get an additional £40 charge on their bills per annum, which may even rise up to as much as £80 by the time the scheme has completed.

Starting in 2015, construction of the Thames Tideway Tunnel is expected to take eight or nine years. It is therefore planned to be completed in approximately 2023.

LCB / BT                                                                                                                                  16.09.14

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