Authorities on both sides of the border are closing in on companies responsible for large-scale illegal dumping at the height of the building boom.
Prosecutions are being sought against a number of firms who illegally transported 250,000 tonnes of household and commercial waste across the border to be buried in Northern Ireland.
Files are being prepared for the Director of Public Prosecutions (DPP) and the Crown Prosecution Service over illegal dumping at 17 secret locations in Northern Ireland between 2001 and 2004.
The Environmental Protection Agency in the Republic and the Northern Ireland Environment Agency (NIEA) have been investigating those suspected of being behind the illegal dumping for the past two years.
Already the NIEA has secured three convictions against property owners for illegally depositing waste from the Republic.
A Department of the Environment spokesperson said that the illegal dumping “involved serious criminality with no regard to the impact on the environment, local communities or our economy”.