Lee Tunnel: Project update

10 January 2011

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The Lee Tunnel

� Four mile (6.9km) tunnel from Abbey Mills to Beckton STW

� Storage and transfer tunnel

� Entire storage space of 382,000m3 provided by both the tunnel and shafts

� Up to 75m underground with an internal diameter of 7.2m

Benefits

� Deals with single worst polluting CSO in London

� Abbey Mills CSO is responsible 40% of the total volume of untreated sewage currently entering the tidal River Thames

� Will intercept 16 million tonnes of untreated sewage currently discharged into the River Thames each year on average, via the River Lee

� Starts and ends on land we already own; requires no intermediate construction sites

Building the Lee Tunnel

� £635 million project – largest contract we have ever awarded

� Joint venture comprising Morgan Sindall, Vinci Construction Grands Projets and Bachy Soletanche (MVB)

� 500 staff (including labour) at peak construction

2010 achievements

� Jan – Site establishment works

� June - Mobilisation on site

� Sept - Start of work on overflow

shaft

� Oct - Spoil handling via the river

� Nov – Start of work on pump

shaft

� Dec – D-wall preparations for

pump shaft

Overflow shaft20m diameter; 74.5m deep

� Work on shaft started Sep 2010

� Due for completion in late Jan/early Feb 2011

The hydrofraise

Construction of the overflow shaft diaphragm wall

Spoil conveyor

Pump shaft38m diameter; 86.5m deep

� Largest and deepest

shaft for the project

� Preparatory works

nearing completion

� Diaphragm walling to

start Jan 2010

Pump shaft site overview

Guide wall construction for the pump shaft

Footprint of the connection shaft

Batching plant

� On site concrete batcher

� Will produce the bulk of

concrete for shafts and

tunnel

� Total concrete to be used

on the project = 143,000 m3

On site concrete batcher

Abbey Mills25m diameter; 68m deep

� Survey works and site establishment underway

� Start on site in Jan 2011

� Construction of the Abbey Mills shaft due to start in summer 2011

Borehole drilling at Abbey Mills

Future key milestones

2011 • Shaft excavation and construction

• TBM arrival

• TBM assembly

S • TBM drive starts

2013 • TBM breakthrough

• MEICA fit out starts

2014 • Tunnel construction completed