A long, long way down!

Lee Tunnel Project - slab 85m down

Lee Tunnel Project - slab 85m down

We are currently involved in pumping concrete for the Lee Tunnel, part of Thames Water’s London Tideway Improvements programme, to create a cleaner, healthier River Thames. This £635m project is designed to help prevent around 16 million tonnes of sewage mixed with rainwater overflowing into the River Lee each year by capturing it and transferring it to Beckton Sewage Treatment Works.

Awarded to MVB, a joint venture consisting of Morgan Sindall, VINCI Construction Grands Projets and Bachy Soletanche, the 7.8m internal diameter, 7km long tunnel utilises a tapered universal ring design comprising seven segments plus a key.

Our work for MVB has been to pump concrete into the four shafts on the project – three at Beckton and one at Abbey Mills. We recently completed pumping the slab at the bottom of the largest of the shafts, the Beckton pumping shaft which is
approximately 85m deep and 38m diameter.

Lee Tunnel Project - pumping 4,300 cubic metres concrete

Lee Tunnel Project - pumping 4,300 cubic metres concrete

The Beckton pumping shaft slab pour was one of the most technically demanding pour that Camfaud has ever undertaken. We supplied three Schwing mobile pumps to pump the concrete, two working and one on stand-by. The delivery pipelines were fixed to the shaft wall by MVB. We bypassed the booms and coupled directly to the pipelines from the backof the pump hoppers.

To distribute the concrete in the slab we erected two Schwing SPB30 placing booms at the bottom of the shaft. A pipeline brake and a hydraulic shut off valve were installed into each pipeline to minimise the risk of the concrete segregating due to the fall and to facilitate clearing the line if it did block.

Lee Tunnel Project - 2 x Schwing SPB30s, 85m down the shaft

Lee Tunnel Project - 2 x Schwing SPB30s, 85m down the shaft

To staff the pour, we supplied two teams of operators working 12 hour shifts. Each team had three operators at the bottom of the shaft to operate the booms and three pump operators at the surface. The pour lasted approximately 50 hours and in this time we placed 4,330 cubic metres of concrete into the slab. The requirement was to place the concrete at a minimum a rate of 80 cubic metres per hour. With excellent service from Cemex and a willing concrete placing gang we achieved an average of nearer 90 cubic metres per hour.