Demolition and dismantlingDemolition by Explosives

At Marsham Street, London, SW1, the former Department of the Environment Headquarters, Brown and Mason were responsible for the largest city close proximity controlled explosives project ever to be undertaken in Europe. 13.5 tonnes of explosives were utilised over a period of five months to assist with the demolition of bomb-proof wartime reinforced concrete structures with roofs and external walls up to 3 metres thick.

Blasting of the tallest chimney ever to be demolished in this way in the UK was undertaken at our Pembroke Power Station site in South Wales.

Bringing down the 217 metres high chimney for Innogy plc set a new demolition record.

The explosives team used 100kg of explosives and 2000 non-electric detonating charges to blow down the reinforced concrete structure and its smaller, 122 metres, sister chimney leaving a pile of 15,000 tonnes of rubble.

The two chimneys were located close to a live National Grid sub station. However, the real challenge related to the main chimney's massive measurements - 69 metres diameter with a wall thickness of 1.5 metres at its base and four brick flues running through its centre.

Because of its significant height a special explosive mechanism was devised to break the structure in half. A first blast made the top half fall one way split seconds before a second blast sent the bottom half in the opposite direction.

The half mile exclusion zone extended out into the sea, necessitating the use of patrol boats around its perimeter.