Wildlife, water and toxic waste worries have been raised by people living near one of Europe’s largest illegal landfill sites as officials look at clean-up options.

The Mobuoy dump, discovered in 2013 more than two miles outside of Londonderry, was used by criminals who buried thousands of tonnes of rubbish at a site stretching across more than 100 acres of land – the equivalent of about 70 football pitches.

Two men were jailed in June for what a judge described as “environmental crime on an industrial scale”.

A public meeting on the clean-up is being held in Eglinton, County Londonderry, where people expressed concern about potential contamination in the nearby area.

One Eglinton resident, Kerry Buchanan, said she wanted reassurance about the safety of the local water supply while another, Robert Ross, said he was in the process of buying a site for a house one mile from the dump site.

“I just wanted to find out what’s happening, how long is the timeframe for doing it and will it impact us in building [a house]?

“We seem to be far enough away but with toxic waste you just don’t know.”

The site at a former quarry in Campsie is near the bank of the River Faughan, which supplies much of Derry’s drinking water.

Although there is no evidence the river has been contaminated, experts were hired to find the best way to deal with the rubbish and protect the waterway.

More than 600,000 tonnes of domestic and construction waste was illegally dumped before the site shut in 2013.

Residents have been hearing from the Northern Ireland Environment Agency (NIEA) about what can be done to clear the site during a public meeting in Eglinton Community Centre on Wednesday.

The proposals were released as part of a public consultation which opened in June.

Some of the rubbish will have to be dug up and removed because the disused quarry is not an appropriate place to store industrial waste.

However, the Department of Environment, Agriculture and Rural Affairs (Daera) has said digging up all the waste may not be the best way to protect the environment.

It advised some of the construction debris dumped at the site – concrete, bricks and glass – could remain in place as those materials do not cause water pollution.

Regular tests show surface water in the Faughan is not affected, but groundwater under the landfill is polluted and the aim is to prevent this leaching into the river.

Ms Buchanan, who lives in Eglinton, said she was looking for reassurance about the safety of the water supply and the impact of illegal waste on wildlife in the River Faughan.

“I just want to know what the plans for the future are and has there been any contamination into the land.”

She said she felt reassured after talking to experts at the event, who explained they are “putting in barriers and things like that” to stop contaminants from getting to the river.

“So I’m hoping that they’ll be able to get all that done because there is movement and there is the concern that it eventually will affect the water.

“It’s not at the minute, but I’m hoping that they can get things in place that stop it happening.”

Robert Ross said there were “plenty of people talking” but “no solid answers” as yet – but he also appreciated the effort that had gone into the event.

“It’s good that they have some sort of information available rather than just depending on the internet,” he said.

Dean Blackwood, chairman and director of River Faughan Anglers, said he had come to the meeting “with some degree of scepticism”.

“The department that failed to address Mobuoy when we [the River Faughan Anglers] were raising these concerns are now the same department that’s charged with remediating the problem,” he said.

However Mr Blackwood said that any steps to address the issues would be better than the current situation “where we are always worried about what could happen in the future”.

“So from that perspective we’re coming with an open mind in terms of wanting to see how best our river can be protected.”

SDLP assembly member Mark H Durkan, who lives about a mile from the dump, said Mobuoy had “loomed large in Derry and across the north west for over a decade”.

Mr Durkan said he was “impressed” by the resources Daerra has invested in the public information event and felt better after talking to the experts.

“I’m certainly assured that the water supply is fine. The level of analysis and monitoring at that particular stretch of water is second to none across the north,” he said.

He said he hoped more people will get the chance to ask questions at a second information event scheduled for Derry next week.

Investigations at the site indicate an estimated 1.6m tonnes of waste was present at the site, some 627,000 tonnes of which was believed to have been dumped illegally.

The area of polluted ground stretches to about 100 acres, or the equivalent of about 65 – 70 football pitches.

Some of the rubbish dates back as far as the 1960s but the illegal waste was linked to two businessmen who were jailed for their role in the scandal earlier this year.

Gerard Farmer, 56, of Westlake in Derry, was jailed for 21 months in June and his co-defendant – Paul Doherty, 67, of Culmore Road, Londonderry, was jailed for a year.

Both men had pleaded guilty to waste offences carried out between 2011 and 2013.

The rubbish was deposited across two parcels of land used by their firms – the Campsie Sand and Gravel company and the City Industrial Waste firm.

The judge at Londonderry Crown Court said both defendants had “acted deliberately” and been “entirely motivated by financial gain”.

The court was told that the amount of waste illegally disposed of could potentially have generated £30m for Doherty’s company, Campsie Sand & Gravel Ltd.

For Farmer’s firm, City Industrial Waste Ltd, the potential sum was more than £13m.

The figure for the potential repair bill is contained in 2022/23 accounts from Daera which were published in February 2024.

They estimate a cost range of between £17m and £700m – however that top range estimate would only apply if all of the waste was dug up and transported elsewhere, which is not what Daera is planning to do.

The most recent estimate stands at £107m to clean up the site using a range of pollution prevention measures.

These include leaving some of the waste in situ and placing a soil cap on top of it, upon which plants would be cultivated to help absorb pollutants.

However, that £107m figure is a “point in time” estimate, which is likely to rise the longer it takes to finalise the proposals and put them into action.

The public consultation was opened by Daera on 13 June and will close on 2 October.

The department hopes those with an interest in how the site can be remedied will respond to the consultation.

On Wednesday, a community event, organised by the Northern Ireland Environment Agency (NIEA), will take place in Eglinton Community Centre from 12:00 to 19:00 BST.

Another event is set to take place on 10 September.