Blowdown success for Safedem

Contractor Safedem successfully used explosives to demolish two 16 storey blocks of flats in the Scottish city of Kincardine on behalf of Fife Council to clear the way for a new low rise development.

Both towers were of Bison Wall Frame Panel construction - a type of structure that has caused problems for demolition companies in the past as witnessed by the 1991 blowdown, also in Scotland, where similar towers failed to collapse following an explosive demolition attempt.

The job was further complicated by the presence of a live electrical substation and two major retaining walls less than 5 m (16.5 ft) from the west elevation of the structures and the presence of old mine workings some 10 m (33 ft) to the east. According to Safedem's managing director and explosives engineer William Sinclair: "We were effectively restricted within a long narrow strip where we had to land the structures. Given the proximity of the mine workings, we also had to reduce the ground vibration to absolute minimal levels."

Overcladding and asbestos removal, soft strip, preweakening, drilling and installation of blast protection were carried out before the blasts. Each tower consisted of 8,000 tonnes of concrete and just 28 kg (62 lb) of explosives was used on each to initiate the controlled collapse.