Ayesa in Manchester in 2017 was initially commissioned to provide consultancy services in relation to the earthworks phase of the development. This remit was later expanded to include the design of below ground foam storage tanks, bearing piles and temporary works. The storage tanks were installed below ground and form part of the hangar’s fire suppression system. Following activation of this system the storage tanks will be used to store the waste foam pumped from the hangar area. Due to high groundwater, the design of the tanks needed to closely consider the potential for uplift of the tanks when empty. To remove the flotation risk, the design incorporated a 400mm thick reinforced concrete base slab, with each tank tied to it using restraint straps. The total depth of excavation was in the order of 6.5m completed in open cut, for which Ayesa carried out stability checks and temporary works design.