Aughinish Alumina has been ordered to increase pollution monitoring after several of the streams crossing the Co Limerick site showed signs of worsening contamination.
The deterioration occurred this year in a number of estuarine streams which link the highly contaminated site to the wider water table. Significant sources of water pollution at the Russian-owned plant included aluminium and arsenic.
In August, an Irish Times investigation showed groundwater beneath the refinery, which produces the raw material for aluminium, contains contaminants up to 4,700 times the thresholds permitted under law.
Analysis of regular groundwater testing reports submitted by the plant to the Environmental Protection Agency (EPA) shows more than half of the wells and streams on the site, located on the Shannon estuary, contained contaminated water in excess of thresholds laid out in Irish regulations.
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Much of the contaminated groundwater contains high levels of aluminium which has, in the past, been blamed by local farmers for unusually high cattle deaths in the area.
This has been strongly denied by the plant, which was cleared by an EPA investigation in the 1990s.
The latest reports show that pollution levels in some areas near the centre of the site have improved. But monitoring in other areas showed significant deterioration, indicating a “plume” of pollution migrating towards the plant’s boundaries.
Despite this, the EPA has taken no enforcement action against the company for environmental breaches.
In one stream, the levels of dissolved aluminium detected in the water increased seven-fold to 2,338 micrograms per litre between the first and second quarters of this year - more than 15 times the amount permitted under environmental regulations.
In August, EPA inspectors conducted a site visit and examined several of the streams. It found the site was compliant with environmental regulations but noted there was “ongoing contamination” of groundwater and that there was “significant pressure” on the local water table.
The EPA ordered Aughinish to increase monitoring of five streams on the site (from quarterly monitoring to monthly) and to test for a wider range of contaminants.
The first of these monthly tests was submitted to the EPA by Aughinish in September. They showed some improvements but severe aluminium contamination remained in two streams. Two streams also contained arsenic levels in breach of regulatory minimums.
Aughinish Alumina did not respond to queries but previously stated all contaminated water is recovered before it can leave the plant and there is no danger to the surrounding area.
Separately, Aughinish commissioned Geosyntec Consultants to carry out an environmental assessment during the summer. The resulting report noted the 85 hectare site sits on a bed of fractured limestone rock which causes “unpredictable” water flows and that the groundwater quality has been assessed as “poor”.
It said efforts to improve the groundwater quality are working and the risk to surrounding groundwater in the region is “low”.
The assessment concluded that pollution on the site is likely due to historic contamination, rather than ongoing leaks from the plant.
