Even though just three remained in operation in 2019, old landfills in Ireland will remain a significant cost in future years due to safety monitoring.
That is one of the conclusions of the annual report of the Comptroller & Auditor General, which recommended that the Department of Environment should conduct a comprehensive review of governance of landfill sites.
Such a review would ensure that responsibilities for oversight and monitoring of landfill sites are clearly defined and assigned, the report said.
It would also ensure that appropriate steps to eliminate risks to the environment and communities are taken in a timely and efficient manner, it added.
As of July this year, the total number of identified landfill sites was 611. By the end of 2019, only three privately operated landfills were still in operation, the report said.
They included 117 sites licensed and regulated by the EPA since March 1997, and which it continues to monitor — 64 sites operated by local authorities and 53 operated privately.
Some 494 unregulated sites are registered by local authorities on a web-based register established by the EPA.
Over 70% of the sites are former local authority-operated landfills. Around 21% were privately operated sites, while just over 8% were illegal dump sites.
The report said that the Environmental Protection Agency (EPA) monitors environmental risk factors on an ongoing basis on the 117 landfill sites it has licensed and regulated since March 1997.
The EPA does not monitor environmental risk factors at the remaining 494 landfills that have been identified by the local authorities and are registered on an EPA-hosted database.
More than half of the 280 sites operated by local authorities and subsequently closed between June 1977 and March 1997 have been assessed as of either moderate or high risk, the report found.
Remediation plans have been submitted to the EPA in only 29 of the 280 sites.
“Neither the EPA, nor the department, nor the regional waste management planning offices were able to provide the examination team with complete information on the risk assessment status of the remaining 214 sites on the register as at December 31, 2019, which included pre-1977 local authority sites, private sites and illegal sites,” the report stated.
It recommended that the department develop proposals for ensuring that all outstanding risk assessments are completed on a timely basis, and that remediation plans be a priority for moderate and high risk sites.
In relation to remediation, elimination or management of any environmental risk posed by a waste-impacted site is priority.
The most frequently used approach is to leave the waste deposited in landfills on site.
This typically requires installing an engineered cap, a drainage system, and landfill gas extraction structures such as gas burned off at a flare, collected for energy generation or released through passive gas vents, with aftercare management of the site extending over many years.
The latter includes ongoing management until the site stabilises and no longer poses a threat to public health or the environment, the report said.
A less-used option is to remove all waste for disposal elsewhere and to fill and restore the landfill site with inert matter.
A third option exists where certain waste may be removed from the site, leaving the balance in situ to be managed appropriately.