Project/Site Name: Atomic Energy Establishment Winfrith
Sector: Power
Scope of Work: Blast Wall Propping / Nuclear Decommissioning
Project overview
Amrose Associates was appointed by Aureos to provide the temporary works design for the propping of an existing blast wall at Atomic Energy Establishment Winfrith in Dorset.
Winfrith is a former nuclear research and development centre established in the late 1950s. Nine experimental reactors operated at the site during its lifetime, including the Steam Generating Heavy Water Reactor and Dragon reactor.
The site is now undergoing final decommissioning, with the long-term objective of returning the land to natural heathland.
As part of a wider programme of modification and demolition works, temporary support was required to maintain the stability of an transformer existing blast wall while adjacent structures and foundations were removed and new permanent works constructed.
The challenge
The transformer blast wall formed part of an established electrical infrastructure installation within a highly constrained working environment.
Transformers, oil coolers, cable trenches, oil pipe trenches, foundations and other electrical equipment were located around the structure, while several existing foundations and components were scheduled for removal.
Excavating and removing structures adjacent to the blast wall had the potential to reduce its existing lateral support, creating a temporary stability risk during the construction sequence.
A propping solution was therefore required that would:
- Maintain the stability of the existing blast wall throughout the works
- Provide controlled resistance to lateral wall movement
- Avoid introducing unintended loads into the existing structure
- Maintain stability as adjacent foundations and ground were modified
- Accommodate existing underground electrical and other services
- Be practical to safely install, inspect and subsequently remove
Our Solution
Acting as Temporary Works Designer, Amrose Associates developed the solution from assessment of the existing blast wall through to the detailed propping arrangement and connection design.
Multiple prop lengths and configurations were developed to accommodate the geometry of the existing structure and restricted working space.
The design incorporated:
- Mabey Mass 10 props
- Adjustable pivot ends
- LG1, LG5 and LG7 Legato concrete blocks
- Waler arrangements
- Threaded tie bars and waler plates
- Mechanical connections between the props and pivots
The modular and adjustable nature of the proprietary Mass 10 equipment allowed the temporary works to be configured around existing structures and site constraints while providing the required support to the blast wall.
One of the principal challenges was designing temporary works within an existing electrical infrastructure environment. Cables and cable trenches were located close to the proposed works, alongside electrical equipment and an 11kV installation. This meant the design needed to consider not only structural stability, but also how the temporary works could be safely installed and removed.
Amrose incorporated requirements covering isolation of the working area, electrical exclusion zones and warning signage, safe working around potentially live electrical equipment and confirmation of existing services and site conditions before construction.
Managing risk
The temporary works design considered the complete construction sequence, including installation, excavation, use and eventual removal.
The contractor was required to inspect the blast wall before installing the temporary propping, with any defects repaired before the structure could be considered suitable for the proposed support arrangement.
Excavation also needed to be carefully managed. The blast wall foundation was required to remain supported throughout the works, with the maximum permissible excavation depth defined within the design.
Suitable RAMS were required for installation and removal, together with a safe system of work to prevent additional unintended loading being imposed on the blast wall.
The outcome
Amrose Associates delivered a fully detailed, construction-ready temporary works solution capable of maintaining the stability of the existing blast wall throughout the modification and construction programme.
Combining proprietary Mabey Mass 10 equipment with bespoke connection details and Legato ballast created a practical solution for a particularly constrained infrastructure environment.
The temporary support was designed to remain in place until the permanent foundation had been cast and backfilling completed to existing ground level, after which the propping could be safely removed.
The project demonstrates Amrose Associates’ ability to bring together structural assessment, temporary stability, excavation requirements, existing infrastructure, electrical hazards and construction sequencing within a single coordinated temporary works design.
Need temporary works engineering support for a complex demolition or infrastructure project? Contact Amrose Associates on 0113 391 9840
