Environmentalists and politicians have called for a public inquiry after two businessmen were jailed for running one of Europe's biggest illegal dumps.
The site at Mobuoy near Derry covers more than 100 acres - the equivalent of 70 football pitches.
On Friday, two company directors who ran businesses at the location were jailed for their part in the crime.
Gerard Farmer, aged 56, a director of City Industrial Waste from Westlake in Derry, was sentenced to 21 months in custody.
His co-accused, 67-year-old Paul Doherty, a director of Campsie Sand and Gravel from Culmore Road in the city, was jailed for one year.
There have been calls for the sentences to be reviewed.
The two businesses were directly across the road from one another. Waste from the processing plant was illegally buried on site. It was also brought across the road and buried in pits dug at the sand company.
The court heard that together, the men had profited to the tune of £40 million.
The waste was dumped beside the River Faughan, which provides a significant proportion of Derry's drinking water.
Stormont's Department of the Environment is monitoring water and has reported no issues with water quality.
Environment Minister Andrew Muir said he believes there is merit in holding a public inquiry into the "abhorrent" illegal dumping.
Mr Muir told the Northern Ireland Assembly he shared public concern over the "appalling situation" in Mobuoy and said he had approved the launch of a consultation on the draft remediation strategy.
He said: "Safeguarding public health, ensuring safe drinking water and reducing the environmental impact of the Mobuoy site is of paramount importance to me.
"There is no quick fix but I am committed to continuing to ensure that appropriate steps are taken to protect water quality and the environment during these processes."
He said to date he had been advised that there had been no adverse impact on the safety of drinking water being supplied from the River Faughan.
Mr Muir said he would be engaging with Foyle MLAs and representatives from Derry and Strabane Council over the site.
Mr Muir added: "It is important we look to the past and understand lessons to be learned, but it is also important we look to the future and have remediation of this site."
But environmentalists remain concerned about the long-term impact of the pollution. Remediation plans for the site have been discussed.
They range from digging the hundreds of thousands of tonnes of waste out to sealing it in place. Removing it could cost up to £700m.
Dean Blackwood, a former planner and environmentalist, said there must be a public inquiry into the affair.
His call has been echoed by a former Northern Ireland Environment Minister Mark H Durkan. The Northern Ireland Assembly voted in favour of an inquiry more than a decade ago.
But the vote was non-binding and the plan did not get Executive approval. In 2020, then-environment minister Edwin Poots said he would not approve an inquiry.
Stormont's Environment Minister Andrew Muir said there was merit in a public inquiry into the dump at Mobuoy but that the UK Government would need to help.
"I will bring a paper to my Executive colleagues in regards to that. What is clear though is that the UK Government need to help us both with the resourcing of any public inquiry but also in terms of remediation costs on the site."
Mr Muir described the actions at the Mobouy site as "a crime of unprecedented proportions".
Additional reporting PA
