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December 18, 2012

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Regulator dropped the ball in fatal dredging operation

The Environment Agency has been ordered to pay a fine of £200,000 after one of its employees drowned while dredging an icy watercourse in Cambridgeshire.

The HSE prosecuted the regulator following an investigation into the incident, which occurred on 8 December 2010, during maintenance work on the Counter Drain at Mepal.

Simon Wenn, 43, was operating a crawler crane, rigged as a dragline, to dredge sediment from the bed of the watercourse between the A142 bridge and Welches Dam. The Agency carried out the specialist maintenance of the 30km Counter drain over a period of 10 years to ensure the free flow of water and prevent flooding.

The operation was carried out during an intensive cold period; the water was frozen and the river bank on which the crane was positioned was frosty and wet. Timber-tracking mats were laid to provide better grip and stability for the work to be carried out, and to protect the grassy bank from damage.

Cambridge Crown Court heard that at around 9.30 am, Mr Wenn was rotating the crane to reposition one of the tracking mats from behind and swing it into position in front of him. However, as it rotated through the water, the crane began to slip down the bank and eventually tipped into the river.

The door of the crane cabin was on the floor of the river bed, trapping Mr Wenn inside. The machine submerged very quickly and, although a colleague of his, who was acting as a banksman, quickly alerted the emergency services, they were unable to free him. He drowned as freezing water filled the cabin and was officially pronounced dead at 8.19pm.

The HSE investigation into the incident uncovered a catalogue of errors, particularly around issues of planning and competent site supervision in relation to re-assessment of risks.

According to the crane manufacturer’s specifications, the maximum length of boom with which the crane should have been fitted when used as a dragline was 16m; at the time of the incident, the boom was 19m. The crane had been in use as a dragline since 1998, yet it had never been identified that a 19m boom was outside the safe working limit.

The investigation also revealed that the crane should have used two chains to lift the mats up and clear of the water. In fact, only one chain was used and the procedure adopted involved dragging them through the water.

HSE inspector Stephen Faulkner explained to SHP that although this method of work had been used on previous operations, the presence of thick ice on the surface of the water increased the likelihood of the mats snagging, which applied extra forces to the crane.

It was also common for mats to be dipped in the water to clean them of silt and dirt but, on this occasion, owing to the icy conditions, the mats froze and became slippery.

The reduced grip on the mats, coupled with the increased risk of extra force brought about by dragging the mats through the icy water, caused the crane to slip towards the river and topple over.

The Agency’s failures in site supervision at the planning stage centred around an inadequate assessment of the technical requirements at the Mepal site, and of the impact of the cold weather. The system of work for lifting and positioning the tracking mats was ultimately deemed unsafe.

The Environment Agency was fined £200,000, with costs of £28,548, at a court hearing on 14 December, after pleading guilty to a breach of s2(1) of the HSWA 1974. Sentencing the regulator, the judge remarked that “someone, somewhere, has dropped the ball”.

Mr Wenn’s death followed a similar incident in Norfolk in 2008, involving a smaller tracked machine operated by employees of the Agency. The report into this incident highlighted the use of tracking mats near water in poor weather, and advised extra management precautions, explained inspector Faulkner.

He added: “The Environment Agency failed to heed warnings and learn lessons from a previous non-fatal incident, in which there were similar failings.

“Our investigations of incidents are not just there to assign responsibility. They are an important source of information to help develop effective policies and procedures to ensure the health and safety of workers. Employers should act upon the findings of such investigations and implement procedures to reduce risks.”

In a statement, Environment Agency Anglian regional director Toby Willison said the loss of Mr Wenn continues to be felt by friends and colleagues at work.

He added: “We have also worked closely with the HSE, emergency services, our employees and the wider construction industry to develop new procedures for working on mats, which did not exist before. €

Approaches to managing the risks associated Musculoskeletal disorders

In this episode of the Safety & Health Podcast, we hear from Matt Birtles, Principal Ergonomics Consultant at HSE’s Science and Research Centre, about the different approaches to managing the risks associated with Musculoskeletal disorders.

Matt, an ergonomics and human factors expert, shares his thoughts on why MSDs are important, the various prevalent rates across the UK, what you can do within your own organisation and the Risk Management process surrounding MSD’s.

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