Paul Fennelly, then aged 45 from Hamilton, was working for Galliford Try Infrastructure Ltd, trading as Morrison Construction, at a site off the B9012 near Duffus, Moray, when the incident occurred on 1 July 2011.

Elgin Sheriff Court heard that after he had been told the water supply had been turned off, Fennelly was cutting a section of cast iron water pipe within a 1.3 metre deep excavation trench.

There was a sudden gush of water from the pipe and when Fennelly took avoiding action and moved to the other side of the pipe, part of the trench collapsed trapping his right leg against the pipe and covering it with clay.

His colleagues dug him out and he was taken to hospital with a snapped thigh bone.

He had an operation to insert a pin and bolts and was in hospital for 10 days. Fennelly had to use walking sticks for five months and was unable to return to work until 11 months later.

He took up alternative employment but is not currently working as he needs a further operation and is still in considerable pain.

An HSE investigation found that Galliford Try Infrastructure had identified the risks involved in excavation work and implemented daily excavation inspections and training in excavation work.

But insufficient consideration had been given by the company to the potential effect of a sudden flow of water to the stability of the excavation.

Galliford Try Infrastructure of Melville Street, Edinburgh, was fined £3,000 after pleading guilty to breaching the CDM regulations.

Following the case, HSE Principal Inspector Niall Miller, said: “Risks relating to the collapse of excavations are long-standing and well-documented.

“As one cubic metre of soil typically weighs between 1.6 and 1.8 tonnes, even the collapse of a small quantity of material is potentially dangerous. Soil collapse can be rapid and completely without warning.

“While the inspection carried out by Galliford Try had concluded that the excavation had been dug appropriately, it had not sufficiently taken the water into account.

“As a result, the company failed to assess whether additional protective measures were needed to prevent collapse, such as sloping or battering the sides or some form of support such as shoring.

“As a result Mr Fennelly has been left with a very painful injury from which he has still not fully recovered.”