Work has officially started on London’s 6.4km long, 7m diameter Lee Tunnel following the groundbreaking ceremony yesterday at one of the tunnel’s four shafts. Boring of London’s deepest tunnel, and Thames Water’s biggest engineering project to date, is due to begin in 2012 for completion in 2014.
The Morgan Est/VINCI Construction Grands Projets/Bachy Soletanche (MVB) JV is constructing the US$990M tunnel that will take discharges from London’s largest combined sewer overflow at Abbey Mills in Stratford, east London, for treatment at Beckton sewage works, which is being expanded so it can deal with the additional flows. The tunnel will be bored through chalk at depths of up to 75m.
The Lee Tunnel will help prevent 40 per cent of the 39 million tonnes on average of sewage which enters the River Thames and River Lee each year from 57 overflow points.
Martin Baggs, Thames Water’s CEO, who cut the first sod at the Beckton shaft site, said, “Sewer overflows used occasionally during the 1800s are now used almost weekly on average and can be triggered by as little as 2mm of rainfall. The overflows cause significant environmental damage – killing fish, contaminating the river for those who wish to use and enjoy it and affecting the wellbeing of our capital.
“The sewers are simply not big enough to cope with a population which has trebled in size and continues to grow, and a city which has paved over many green spaces preventing natural drainage.
“We have a plan in place to tackle this. Abbey Mills is the largest sewer overflow in London so the Lee Tunnel will deal with this first so we can have the biggest impact, most quickly.”