Inner city work a blast - Norfolk Court implosion
By Lindsay Gale15 October 2010
UK contractor Safedem completed a challenging contract when it imploded the 24 storey Norfolk Court tower block in the heart of the Gorbals area, just a half mile away from the centre of Scotland's second city, Glasgow. Located just 6 m (20 ft) from a major road and at one corner of a busy crossroads, the tower was surrounded by public buildings on the other three corners. As a result, Safedem had to develop a collapse mechanism that ensured that the 22,000 tonne structure landed precisely within the confined site limits.
A 180 m (690 ft) exclusion zone was established, requiring the evacuation of more than 500 households, and adjacent buildings were provided with scaffold screens with debris netting around glass canopies and entrances. In addition, window seals, air intakes and vents were sealed to prevent dust ingress. Dust suppression systems were also installed. Evacuation was complicated by the fact that a nearby tower block was being used to house asylum seekers, requiring Safedem's newsletters and resident questionnaires being translated into 19 languages to ensure clear and concise communication.
According to managing director William Sinclair: "we applied a delay pattern throughout the structure which would minimise ground vibration and introduce high degrees of shear through the collapse to maximise break-up. When you drop a structure you often get an element of run-off from the debris pile - at Norfolk Court we wanted to bias the structure away from nearby Gorbals Street but we also wanted the material to hit the brakes at ground level rather than rolling away from us. This was achieved by getting the structure to gently tilt then be controlled by a diagonal delay pattern - it was just about as perfect as it gets."