Probe into toxic sludge risk at former Caithness waterworks
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WATER and sewage treatment at a Caithness site has potentially led to a toxic sludge linked to cancer and Alzheimer’s infecting the surrounding environment.
The Old Calder works near Halkirk is one of 25 sites across Scotland currently under investigation into possible contamination.
According to a report from the Scottish Environment Protection Agency (SEPA), harmful waste that includes traces of aluminium and other pollutants used to purify water has caused harmful pollution at the site.
The resultant sludge is said to contain aluminium which has been linked to breast cancer, Alzheimer’s and other health problems.
Scottish Water has launched an investigation into the potential hazard of the sludge lagoons across the country, including in Caithness, where environmental campaigners are demanding action.
SEPA East region area manager Colin Anderson describes the risk to the public as low and said that it would work with Scottish Water during the investigation.
"Six of the 25 sites contain old sewage sludges or cakes and 18 sites contain water treatment sludges or cakes, with one site containing both," he said.
"The old sewage sludges are relatively benign, for example, sewage sludge can be applied to land as a soil conditioner, subject to good practice being followed.
"With regards to water treatment sludges, alum coagulant is generally used to bind together microscopic particulates and organisms in source waters prior to removal by filtration and, as such, the associated sludges will contain aluminium.
"The risk of such aluminium leaching is very low as the binding nature of the alum means it tends to remain in the sludge or cake rather that leach out into the surrounding environment.
"SEPA will continue to work closely with Scottish Water to ensure suitable remediation is undertaken where required."
Campaigners argue that aluminium toxins could break down into liquid and infect the surrounding environment with detrimental consequences.
Neither SEPA or Scottish Water were able to confirm how much sludge existed at the Old Calder works but said that at a site near Cupar in Fife, there could be up to 2000 cubic metres – enough to fill an Olympic swimming pool.
A Scottish Water spokesman said that the lagoons date back to 2002 when local authorities provided water and waste water services and that there had been little or no activity on them since. Scottish Water took ownership of these sites when it was formed 10 years ago.
He said that given the nature of the material and the historic nature of the sites, it is not believed they present a particular risk.
Scottish Water is to undertake environmental surveys to determine the most appropriate means to manage them, in agreement with SEPA.
"Water and waste water sludge arises from the treatment of water for drinking and the treatment of society’s waste water," he said.
"Our focus is always to ensure we manage the material in a sustainable way.
"Predominantly, these sites stored water and wastewater sludge within drying beds.
"For waste water sludge, it is recognised that the most sustainable means to manage this material is to recycle it to land to conserve the organic and nutrient properties.
"Water treatment sludge is a predominantly inert substance. Some water companies recycle this material to land, however Scottish Water mostly disposes it to landfill as there is limited requirement for this material, however, we are exploring further opportunities to recycle this material."
