Temporary Works
King’s College School, Wimbledon, London, UK
Project Brief
LSY Engineering Consultants Ltd was appointed to provide temporary works design services for the construction of a new swimming pool facility at King’s College School, Wimbledon, as part of a wider programme of improvements to the school’s sports and leisure facilities.
Our scope of works included the design of excavation support systems for a new pumping station, comprising sheet pile retaining structures, Groundforce waling systems, temporary propping arrangements, and formwork solutions required throughout the construction process.
Given the school’s requirement to remain fully operational during the works, the temporary works strategy needed to prioritise safety, minimise disruption, and provide a practical construction solution within a live educational environment.
Challenges
One of the primary project constraints was the requirement for the school to remain fully operational throughout construction. To minimise disruption to pupils, staff, and daily school activities, the contractor proposed the use of a proprietary Groundforce shoring system from the outset of the project.
The intended construction sequence and temporary works methodology were reviewed and agreed during the initial project meetings before design development commenced. However, during the detailed design stage, structural assessments identified that the anticipated design loads could potentially exceed the capacity of the contractor’s preferred support system. This created a significant engineering challenge, as any increase in temporary works requirements could affect both the available working area and the contractor’s planned programme.
Process
As part of the design brief, a comprehensive ground investigation had been undertaken to establish the site’s geotechnical characteristics. LSY carried out a detailed review of the available borehole information and ground conditions to confirm the design assumptions for the temporary excavation support system.
During this assessment, it was identified that groundwater pressures could generate approximately 500mm of hydraulic head acting against the sheet pile retaining structure. This additional water loading increased the design forces acting on the excavation support system and created the potential for significantly higher loading than initially anticipated.
The increased forces indicated that larger walers may be required to satisfy the structural design criteria. However, introducing larger structural elements would reduce the available working space within the excavation, potentially affecting construction operations and the contractor’s agreed methodology.
To overcome this challenge, LSY revised the temporary works arrangements and coordinated modifications to both the formwork and propping systems. These adjustments maintained the required structural performance while preserving the working space originally anticipated by the contractor. Through careful design optimisation and collaboration with the construction team, the excavation support system was adapted to accommodate the increased loading conditions without compromising buildability or project efficiency.
Outcome
The project was delivered successfully, with the temporary works solutions enabling construction of the new swimming pool facilities while allowing the school to remain fully operational throughout the programme.
The revised excavation support arrangements provided the necessary structural performance while maintaining the contractor’s required working area, ensuring that construction activities could proceed safely and efficiently.
The works were completed on programme, and the client was highly satisfied with both the engineering solutions provided and the overall project outcome.
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