Appearance of sinkholes near oil drill site and pipeline for gas sparks concern

Local Farmer Davy Hamilton, whose land the holes opened up on, said he was worried that the drilling by InfraStrata and others may have disturbed the ground, possibly undermining a number of old drains.

The holes appeared close to a major gas main operated by Mutual Energy, and there are also old salt mines in the area.

"The hole has been there about two days," Mr Hamilton told the Belfast Telegraph.

"I sowed the field with fertiliser and the tractor was going backward and forward. If it had fallen then, it could have wrecked something.

"I happened to be spreading slurry when I noticed it. I got out of the tractor and had a look at it and kept off it.

"It was about two feet deep, just a perfect round hole. Further down, it was straight, going in a slant to undermine the ground. We were worried it might have been disturbed."

Investigators from Mutual Energy and Geological Survey of Northern Ireland have visited the site in a bid to discover the cause of the sinkholes.

But Mr Hamilton said he had seen them nearby before. "We rented a bit of land from the Belfast Water Commissioners and it fell," he explained.

"You just would not know until due course whether these things could get worse over the next few years.

"We are going to dig around it. If there is anything worse, we will go from there."

A spokesman for Mutual Energy said: "Following the appearance of reports on social media of the emergence of a number of sinkholes in the Liberty Road area, Mutual Energy Limited, which owns and operates gas pipeline assets in the area, is satisfied that these sinkholes are not in the immediate vicinity of the Belfast gas transmission pipeline. Obviously preserving the safety and integrity of the gas pipeline is of absolute importance, but we are satisfied that these sinkholes do not pose any threat."

Campaigners for Stop The Drill said the sinkholes did not look natural. Spokeswoman Majella McCarron added: "They seem to be in line with the drill and are beside the pipeline. These are not natural. The ground has fallen away and it goes deep under and way off horizontal - like a tunnel - and we've never seen anything like this before. Salt mines are a prominent feature in the area. The photos don't convey the depth of the soil falling away."

The development came as the campaign group claimed that members of Belfast City Council's growth and regeneration committee had at a recent meeting expressed serious concerns about the long-term effects of the drilling at Woodburn

InfraStrata, which led the project, declined to attend the meeting. The scheme was halted several weeks ago after no oil or gas was found.

NI Water said: "Measures to ensure the safety and security of the water supply were implemented and closely monitored throughout the process."