Non native flatworms from New Zealand could increase the cost of improvements to a Black Isle school by a six-figure sum.
Disposing of the tonnes of worm contaminated earth in landfill dumps will add at least £100,000 to the spiraling costs of making improvements to Cromarty Primary School.
The infested soil needs to be taken away from the school site to make way for new foundations.
It cannot be reused for gardening or building purposes because of the flatworm’s presence.
It will either be disposed of at a landfill site, which would incur huge tax costs, or shifted to another site already infested with the creatures.
The New Zealand flatworm is an invasive species in Europe which feeds almost entirely on local earthworms.
This in turn degrades the quality of the soil and has an impact on agriculture, biodiversity and wildlife.
The total cost of the school extension project has increased from £2 million to £2.75 million.
This £750,000 overspend has been blamed on the additional cost of land purchase and of items in the original budget, as well as the flatworm problem.
The flatworms were discovered during a recent survey of the school site.
Councillor David Alston, deputy leader of Highland Council, said: “I don’t have the details of the cost yet but it will be a six-figure sum. Cromarty has New Zealand flatworms so the soil could be moved within Cromarty but I am not sure whether that is viable. If it does need to be moved to landfill then that is where all of the cost will lie.
“I think it’s quite a widespread problem and I know there are lots of places throughout the country – not just in the Black Isle – which get them.
“As an invasive species, the New Zealand flatworm is not well known. But certainly I don’t have any earthworms in my own garden because of flatworms. Anyone that’s interested in organic farming knows that they cause real problems. It’s about learning to live with them.”