WEST Somerset's geology and soil structure could have made the trench that killed Stephen White particularly hazardous, the inquest jury was told.

And coroner Michael Rose said the tragedy was a warning to anyone planning to dig a trench.

"I cannot over-emphasise the need to take precautions," he added.

A report by Martin Rickard, of the Health and Safety Executive (HSE), who visited the site after the accident, said comparison was made between the geology of West Somerset and other areas.

It was found that the soil in West Somerset - a silt and sand mix with slate and clay - crumbled easily, making it unstable.

HSE Inspector Simon Chillcott told the inquest: "While we were there, the fire brigade was trying to excavate but the soil was crumbling; there were no solid lumps.

"Clay can look stable but you can get a fault line in it, which means it can slide even if it looks safe.

"People get caught out regardless of how safe they think soil is."

Mr Chillcott said that, as a rule of thumb, a trench deeper than four feet should either be shored up or both sides angled at 45 degrees to prevent any landslide collapsing on top of anyone inside the excavation.

The HSE conclusion was that the immediate cause of the accident was an unsafe excavation.

Mr Chillcott said that such a deep trench that was neither shored up nor battered back could be dangerous even above and outside it.

"You could go to the edge of a three-metre drop and, if the sides are going to collapse, you would be standing on the bit that would fall," he said.

The inquest heard that the sides collapsed on to Mr White immediately after he hit slate with a metal bar in an effort to remove a kink in the pipe. Mr Rose asked whether that was enough to cause the collapse.

Mr Chillcott said: "It could have been the trigger event but equally he could have been just stood there and, without any warning, it could have collapsed."

Mr Rose said that 38 people were killed in similar accidents in the ten years 1986-96 and the number dropped to 11 between 1997 and 2004.

Mr White rented the land on which the accident happened. Mr Farrant, who owned the land with his brother, said it was Mr White's decision to look for a natural spring: "Stephen found it. He wanted it for his dwelling," said Mr Farrant, who was also a lifelong friend.

Mr Chillcott said businesses were "not expected to know the subtleties" of the law and regulations but it was their duty to make sure conditions were safe for a construction worker that they employed.

"There are so many guidelines because the risk is so great," he said.

"In this specific circumstance, the moment it became apparent to David Farrant that matters were not being undertaken in a way he considered safe, he made efforts to stop the work carrying on."

The jury, in its conclusion, said the accident was due to unsettled materils and failure to adhere to safety warnings and precautions, adding: "He was ultimately responsible for his own work."

Mr Rose said the temptation to save time and money by going down the trench was understandable and "99 times out of 100" uneventful.

"But I must emphasise that it is essential that precautions are taken," he said.