The aging substation building at Upton Valley, Torquay contained an existing mezzanine floor dating back to the original construction. The switch gear was of similar vintage, housed on the ground floor and was to be renewed at mezzanine level within a newly constructed 11kV switch room, with full fire containment.
The existing composite steel and concrete mezzanine floor structure could not be relied upon and also had to be replaced. This involved some highly specialized robotic demolition employed to “munch” the existing mezzanine slab under controlled conditions. Due to the sensitivity of the existing adjacent equipment [which included a live open switch board] and the need to keep the whole site energised throughout, robust protection measures were necessary. Sensitive relays and adjoining Local Authority offices meant that vibration, noise and dust had to be suppressed to the minimum. The dynamic loading for the new switch gear itself was transferred to new ground-bearing RC pad foundations cut out of the existing ground floor slab by diamond sawing for isolation and coring sections for lifting.
The new mezzanine construction involved galvanised steel decking, on a galvanised structural steel frame, with 16m³ of structural concrete pumped to 1st floor level through a high level window opening.