CAPITAL SQUARE, EPSOM
This underground car park is under pressure from a very high local water table. Formed by welded steel piles, the waterproofing detail failed at the top of the steel where the capping beam did not cover some piles and at the base where water entered the car park and pooled across the floor.
Although BS8102:2009 only requires a Grade 1 environment (seepage and damp areas tolerable) water was present in areas to a depth of 15mm. Several ‘Heath Robinson’ methods of containing water had been attempted before we designed a system,
We waterproofed with Vandex BB75E to guide the entering water into an internal gutter. Six sump chambers were cut into the existing slab equidistant around the perimeter. Each sump contains two high capacity Newton NP750 sump pumps and has a full battery back-up system. We allow the water to enter the car park but manage its collection and guide the water to the sump chambers.
All sumps are serviced by Stonehouse through our annual maintenance contract. We also took the opportunity to successfully seal one of the lift pits using resin-injection techniques.
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