Water ingress and floatation during construction

Basement – UK

This matter involved a property with a single-storey basement over the entire footprint.  Construction of the basement, within an open excavation, was essentially complete when the site was closed down for a two-week period.  On returning to the site, it was discovered that the excavation had filled with water and the basement box was floating some 700mm above formation level.

WJM&P were engaged as engineering experts by solicitors acting for the consulting engineer to determine the cause of the floatation and whether there were any shortcomings in the engineer’s work in this respect.  Our investigation revealed that water ingress was an ongoing issue, which had been dealt with by temporary pumping.  Over the two-week site close down the pumps had been removed, resulting in the excavation filling with water and the basement box floating.

The employer claimed that the engineer should have warned the contractor of the risk of floatation associated with removing the pumps.  The dispute was resolved via adjudication.