London Gateway Eastern Outfall
Challenge
Laing O’Rourke/Dredging International JV are the main contractors for building the new London Gateway Port. The site was an undeveloped marsh area protected by an Environment Agency flood defence wall that could not be breached. To manage rainwater run off from the 300 hectare site, surface water had to be pumped over the wall by high volume pumps without degrading the river bank.
Solution
SeaTec installed piled concrete plinths to stabilise the manifold and pipework for 8 million cubic metre per hour maximum discharge outfall on both the land and river side of the wall including formwork design and installation, lifting and ancillary plant. The river side tasks required working in tidal waters for piling, rebar and concrete operations with provision of marine safety supervision, training, and rescue facilities for contractors working outside the wall plus additional safety coordination with vessels and the Sierra oil jetty operators. Pumping large volumes of water onto the river bank presented a scour hazard mitigated by the installation of gabion and grout mattresses. Due to the exposed site and the severe wave action the gabions were specially designed with protective kerbs to extend service life and reduce distortion.
The river bank was uneven, containing boulders and obstructions that were surveyed and remediated with additional stone added to infill low areas producing a within specification platform for mattress installation. SeaTec coordinated activities of multiple trades, floating plant and contractors and ancillary contractors in a hazardous marine and oil environment.