Oct 4 2007
The Health and Safety Executive (HSE) has warned construction companies of the dangers of using improvised procedures when dismantling heavy machinery.
The warning follows the successful prosecution of Dawson-Wam Limited of Westoning Road, Greenfield, Bedfordshire, after an employee, John Walsh, was killed when the auger drive unit of a piling rig he was attempting to dismantle flew off its stand and struck him on 13 September 2002. Dawson-Wam Limited had been contracted to carry out piling around the perimeter of the site to form a retaining wall, enabling the site to be excavated for the construction of a new office block.
Dawson-Wam Limited pleaded guilty to breaching Section 2(1) of the Health and Safety at Work etc Act 1974 and was fined £100,000 and ordered to pay costs of £76,128.68 at Croydon Crown Court on Wednesday 26 September 2007.
Two piling machines were used, each comprising a carrier with a leader mast and an auger bit unit. Part of the process by which the machines were dismantled involved lowering the auger drive unit onto a stand. Once on the stand the unit was intended to be separated from the leader mast by hydraulic release of two grab pins.
The hydraulic mechanism failed during the dismantling of both piling machines. On the first occasion a number of improvised methods were tried before deciding to disconnect the drive unit from its backplate. The unit would remain on its stand while the backplate was swung away. This method was passed on verbally but it appears there was no appreciation that when the backplate was sung away the drive units’ centre of gravity would be fundamentally altered.
On the second occasion that the hydraulic release mechanism failed Dawson-Wam Limited’s employees, including Mr Walsh, tried the improvised method used previously. However the stand design was different and did not allow the backplate to swing away. Mr Walsh tried to free the motor by fastening chains to the auger drive unit and connecting them to the arm of an excavator. The excavator pulled the chains, causing the drive unit to fly off the stand and strike Mr Walsh, who sustained serious injuries from which he subsequently died.
HSE Inspector Alec Ferguson said, "Where a pulling force is exerted by using an excavator, the load can increase rapidly to very high levels, leading to a sudden release when the point of resistance is overcome. Employers need to ensure that where circumstances prevent the use of standard methods of work, then the risks arising from any method subsequently adopted should be very carefully assessed. In particular, employers who are even considering departure from manufacturer’s guidance in respect of specialist equipment should assess the risks which may result very carefully indeed before proceeding. Attempting to dismantle heavy equipment in a way not recommended by its manufacturer is likely to be a very risky enterprise which should only be embarked on when absolutely necessary and, even then, only following very careful planning of a truly safe system of work."
Dawson-Wam Limited accepted that it failed to suitably assess the risk from dismantling the piling rig in a different method from the manufacture’s operators manual, and that it failed to provide adequate instruction and information to its employees for dismantling the drive unit from the carrier in such circumstances.