Groundforce supports live water works expansion: temporary works lessons for engineers
Reviewed by Tom Sullivan
First reported on The Construction Index
30 Second Briefing
Groundforce Shorco is providing temporary works for Mott MacDonald Bentley on Severn Trent’s £56m upgrade of Longbridge Water Treatment Works, boosting treatment capacity from 734 to 1,261 litres/sec with four 32m-diameter final settlement tanks and a 27m-diameter primary tank. A 10.8m x 10.4m x 8.48m deep excavation in weak, high water-table ground is supported by 12m L605 sheet piles with 3m toe-in and four levels of Super Mega Brace hydraulic frames. The live 1,800mm, ~80-year-old concrete sewer is carried on eight heavy-duty slings from a Mega Brace beam, designed for 49.5kN/m pipe load and up to 77.5kN per strap, with daily monitoring to 1mm movement tolerance.
Technical Brief
- Existing 1,800mm concrete sewer, ~80 years old, had to remain fully live with zero flow interruption.
- New tunnelled pipeline is 50m long and ties in via a perpendicular connection to the existing main.
- Concrete surround is constructed around a short exposed length of the live pipe within the deep excavation.
- Existing pipe is carried on eight heavy-duty lifting slings hung from a single Mega Brace beam.
- Sling layout was engineered so each strap carries up to 77.5kN, against a line load of 49.5kN/m.
- Pipe support design specifically addresses bending and cracking risk once founding soil is removed beneath the barrel.
- Daily survey monitoring of the suspended sewer checks for movements down to 1mm, triggering strict control measures.
- Installing sheet piles and heavy frames around a live, ageing trunk sewer drives a high level of temporary works risk management.
Our Take
Groundforce Shorco’s role at Longbridge Water Treatment Works fits a pattern in our database of the company taking on complex, high‑risk temporary works, similar to its deep basement bracing jobs in Canary Wharf and Hendon, which signals growing confidence from clients in its modular hydraulic systems for critical infrastructure interfaces.
With Severn Trent Water and Mott MacDonald Bentley involved, this UK scheme sits alongside other MMB water projects in our coverage (including its Australian expansion via Leed Engineering & Construction), suggesting that Longbridge is part of a wider push by MMB to leverage integrated design–construct capability on technically constrained water assets.
The very tight 1 mm movement monitoring threshold on an 80‑year‑old live pipeline implies a monitoring and control regime more akin to high‑consequence urban basement works than typical utility upgrades, which practitioners may want to note when scoping temporary works for ageing water infrastructure in constrained UK sites.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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