Work is set to begin next month on the Lee Tunnel this month as the MVB consortium starts coring work to remove obstructions on site.
The £600M mega sewer, thought to be the single largest construction contract from the water industry in the 20 years since privatisation, will take wastewater east from Abbey Mills Pumping Station to Beckton Sewage Treatment Works, which will be expanded to deal with the increased volumes.
At 75m, the tunnel will be the deepest in the capital. The 7km long sewer will prevent more than 16Mt of sewage entering the River Lee, a tributary of the Thames.
The Lee is the first of the London Tideway Tunnels which aim to capture overflow sewage from 36 of the most polluting points across the capital which discharge waste into London’s rivers.
The more complex 32km Thames Tunnel, which will complete the London Tideway project, will go from west London to Beckton, although the precise route is yet to be determined. The project is expected to go out to public consultation in July.
The MVB consortium - of Morgan Est, Vinci and Bachy Soletanche - was originally due to start on the Lee Tunnel site in April, but diverting the extensive utilities which crisscross the site has overrun.
NCE sister magazine Ground Engineering has learned that work will now begin on coring obstructions from the wealth of ground structures from the former waterworks at Beckton in early May.
The 7.2m internal diameter tunnel will be double-lined to manage the massive internal water pressures along the route.
There are four shafts to the tunnel: a 25m diameter, 72m deep shaft at Abbey Mills to collect and transfer dirty water into the tunnel and three shafts at Beckton, a 82.5m deep pumping shaft, a 81.35m connection shaft and a 79m overflow shaft.
Construction on the shafts’ diaphragm walls is set to begin in August and completion is due in 2014.