Castor Park, Kent

The original Castor Park land includes an old quarry in the north-eastern section, which has been partially backfilled, adding complexity to the ground conditions.

Initial assessments identified the site as largely suitable for shallow foundations. The presence of very hard, shallow Hythe Formation rock made piling an economically un-viable option. Instead, ground-bearing rafts and strip foundations were considered the most appropriate solutions where the bedrock was shallower than 3m, with piling considered where the bedrock was deeper.

SPEEDECK commissioned further geotechnical investigations to investigate the depth to natural ground across all plots.

Based on this, SPEEDECK designed shallow strip foundations across much of the site, utilising ground bearing and piled rafts in other locations where bedrock was deeper. This hybrid solution not only reduced construction risk but also ensured cost-effective and warranty-compliant delivery.

The engineering team ensured early engagement with the warranty provider to confirm the suitability of this approach and mitigate future risks. The foundation system was tailored to accommodate varying ground strengths and potential fill zones, particularly in the south-west of the site.

The project was split into two phases and carried out over a 14-week construction programme. This was primarily to enable the waste material from excavations in phase 1 to be used as fill to raise the level over the old quarry in phase 2.

SPEEDECK’s construction scope included:

• Blinding preparation
• Piling (where required)
• Raft construction
• Installation of concrete rafts