Whyteladyes, Cookham, UK

Project Brief

Cadent Gas Ltd, the UK’s largest gas distribution network, appointed LSY Engineering Consultants Ltd to provide structural engineering services for the redevelopment of an existing governor station facility.

The project involved the demolition of an existing building housing a gas governor, termination of existing services and pipework, and the construction of a new reinforced concrete raft foundation to support a replacement governor kiosk. Part of the existing concrete slab was retained and integrated with a new foundation extension, requiring careful consideration of load transfer, detailing, and construction sequencing.

LSY worked closely with Workflow Services Ltd, Cadent Gas Ltd, design managers, and mechanical engineers throughout the project, providing structural design input and coordinating with the wider project team to ensure the successful delivery of the scheme.

Challenges

The site had been largely unmaintained for a number of years, creating several challenges during the early stages of the project.

Prior to any design work commencing, a range of specialist surveys were required, including:

• Ecological surveys
• Arboricultural assessments
• Asbestos surveys

These investigations, coordinated by the project manager on behalf of Cadent, identified the presence of asbestos-containing materials within and around the existing building. As a result, appropriate remediation and removal works were required before demolition could proceed.

Another key challenge was the lack of information regarding the existing ground conditions. Trial hole investigations were therefore necessary to establish foundation details and determine the allowable bearing capacity of the underlying soils.

In addition, the building’s existing electrical supply required safe isolation and removal before demolition works could commence. This involved coordinating with SSE to trace, disconnect, and terminate the existing power supply, ensuring the site could be safely prepared for redevelopment.

The project also experienced several scope changes throughout the design process, requiring a flexible and collaborative approach to maintain programme requirements.

Process

LSY commenced the design process by obtaining detailed information regarding the proposed replacement governor kiosk, including dimensions, weight, and operational requirements.

The new kiosk measured approximately 9.1m x 7.5m and imposed a structural load of approximately 9,500kg. This information enabled us to establish the design loading criteria for the proposed raft foundation and assess the interaction between the retained and newly constructed sections of slab.

Following the completion of site investigations, trial hole results confirmed an allowable ground bearing pressure of 50kN/m². This information formed the basis of the foundation design and enabled detailed calculations to be undertaken for:

• Concrete specification
• Raft slab thickness
• Reinforcement requirements
• Serviceability and bearing checks

LSY developed the full reinforced concrete design package, including:

• Bar bending schedules
• Dowel connection details between existing and new foundations
• General arrangement drawings
• Reinforced concrete detailing
• Structural calculations

Particular attention was given to the interface between the retained slab and the new foundation extension, ensuring adequate structural continuity and load transfer between the two elements.

During the design process, Cadent provided operational clearance requirements relating to existing pipework on site. A minimum clearance of 200mm was required to facilitate the formation of protective sand pits around the gas infrastructure. These requirements were incorporated into the structural design and clearly identified within the project drawings to ensure compliance during construction.

To support quality assurance during the construction phase, LSY specified the required concrete testing and inspection procedures in accordance with industry standards and project requirements. This ensured that material quality and workmanship could be verified throughout the construction process.

All calculations, drawings, and supporting documentation were prepared in accordance with the Cadent G17 approval process, resulting in successful approval of the proposed structural solution.

Outcome

The project was successfully delivered in accordance with Cadent’s programme requirements and operational objectives.

Despite multiple scope changes throughout the design process, the collaborative approach adopted by LSY and the wider project team ensured that the redevelopment works progressed efficiently and without delay.

The new reinforced concrete raft foundation provided a robust and durable platform for the replacement governor kiosk while accommodating existing infrastructure constraints and site-specific operational requirements.

The successful completion of the project further strengthened LSY’s ongoing relationship with Cadent Gas Ltd and demonstrated our ability to deliver practical, cost-effective structural solutions for critical utility infrastructure projects.

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