P J Carey
Southgate Shopping Centre
Bath is a UNESCO World Heritage site famous as the site of Britain's only hot springs. Every day over one million litres of water at 46°c rises from deep below the city and flows through the Roman Baths to the river Avon.
The Southgate Bath development is only a few hundred metres from the site of the baths and has been carefully designed to blend in with the existing Georgian architecture using Bath Stone cladding on much of the project.
The project includes an underground car park with 860 spaces together with an underground delivery area for the retail units. This large basement area was constructed in a secant piled cofferdam roughly 80m wide and 160m long. The excavation was over 10m deep and there was concern that the underlying aquifer which feeds the thermal springs could cause the base of the excavation to heave. All excavations in Bath greater than 5m require consent from Bath and North East Somerset Council before starting, and although the initial site investigation showed that the risk of encountering artesian water was low, the dewatering system was designed to cope with this. The wells could be sealed at any point during the drilling or pumping to prevent artesian flow, and they were designed so that they could be effectively sealed on completion of the pumping.