Rowlands Castle

Techniques used: SFA piles & Rapid Deck

Number of piles: 527no.

Diameter: 300mm & 350mm

Depth: 7m - 12m

A development of 34 new build units with associated garages and additionals for a total area of 2358m² required pile foundations due to the close proximity of trees surrounding the site and high volume change potential clay being present. Therefore, use of traditional foundations was not a viable option. The site was also situated over an aquifer and to avoid contamination, Portsmouth Water Board restricted the depth of piles to a max of 12m below ground.

After our highly experienced engineering and contracts team collaborated to review the scope of the project, it was clear that our Rapid Deck System using SFA piles would be the most cost efficient and suitable solution. The team began working on the design of a 225mm thick voided Rapid Deck engineered scheme, whilst also designing the blinding layer to double up as a piling platform. This offered the client significant programme and cost savings by not having to install a piling mat. The Rapid Deck system also minimised excavation depth, which in turn, had a positive effect on health and safety on site and removed the risk of trenches collapsing in the event of adverse weather. 

As Portsmouth Water board restricted the depth of the piles, it meant that the engineering team had to include more piles to negate this issue, whilst also keeping overall costs to a minimum. 

Ensuring that all foundations were appropriately heave protected was key to ensure no subsidence issues would evolve in the future. 225mm thick Pacavoid was used underneath all rafts to create a suitable void space, along with specifically designed cages for all piles to ensure the foundations cater to the high volume change potential of the clay.

Whilst on site, our contracts team also closely liaised with our client to sequence our works. This meant we not only finished within the programme, but also allowed our client to start critical works ahead of schedule.