Sewage system upgrade, London UK

Project facts

Description Sewage system upgrade, London
Challenge Design and errect access solution for deep curved tanks

Equipment and expertise provided by SGB (Formerly Harsco Infrastructure) was used in a £50 million project to upgrade a major London sewage works. Harsco provided a bespoke solution for the project to help create two new 24m-high underground storm tanks at the plant.

The upgrade project involved rebuilding the plant’s sewage inlet and installing a new pumping station, plus an improved screening system to remove debris and prevent blockages. This required the creation of two new 18m-diameter underground storm tanks which would hold the excess sewage flows that can be generated during periods of heavy rainfall.

"Using traditional birdcage scaffolding to construct these tanks would have been expensive, and also difficult to manage inside the cramped excavation areas that were available," explains SGB’s Mechanical Access Director, Cameron Reid.

"We suggested an alternative solution, using four MASTCLIMBERS™ which would allow the tanks to be constructed from the inside. Although it is very unusual to use this type of equipment in such a deep underground excavation, we knew that this would deliver the high degree of flexible access that this project required."

Normal MASTCLIMBERS™ with 'straight' faces would not have provided sufficient access to the curved walls of the tanks. To overcome this Harsco modified the mastclimbers to create curved faces, which gave the workforce direct access to the tank walls so that the steel reinforcement frame could be installed more easily and efficiently. The MASTCLIMBERS™ were then pulled back a short distance into the centre of the tank to create space for shuttering to be installed and concrete poured.

"Safety is always the key objective for SGB on any project, and a major safety consideration here was the lack of any firm structure to tie the MASTCLIMBERS™ into before the walls were build. We overcame this by developing two special tie-in mechanisms that could be used, one right at the base of each MASTCLIMBER™ and the other attached to an existing wall at the top of the excavation."

Cameron Reid, Mechanical Access Director

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