Millions set aside amid risk of toxic water flood at former landfill site

Dale Spridgeon, Local Democracy Reporter

Millions of pounds have been set aside to manage the risk of harmful contaminated waste and water flooding out of a former landfill site on Anglesey.

Councillors have been told there is a risk a culvert could completely collapse at the former site at Penhesgyn, which would require major work to mitigate a “flood of toxic water” spilling from the site.

The culvert has already partially collapsed, and a report stated that while there was “uncertainty” about whether the culvert would collapse further, “there is still a risk that it might”.

Significant costs

A solution for the situation would be “difficult to estimate” but the report pointed to “significant costs” to stem a flood of contaminated waste and water.

The details were laid out in the council’s statement of accounts for 2024/25, which were accepted during an extraordinary meeting of the council on Wednesday, October 28.

At the start of the year, the provision for Penhesgyn former landfill site was £4.247m, the report stated.

This had included £2m earmarked for the “potential total collapse” of the culvert at Penhesgyn, which it stated “would lead to harmful contaminated waste and water flooding out of the site”.

It described how the culvert had “partially collapsed,” although its condition in 2023 was said to be “similar to when it was inspected in 2003”.

Uncertainty 

The report said: “If the culvert collapses further, a solution for this is difficult to estimate, and there would also be significant costs of installing over-pumping infrastructure needed to mitigate a flood of toxic water while a solution to the collapsed culvert is completed.

“While there is uncertainty about whether the culvert will collapse further, there is still a risk that it might.”

Reports produced by the council’s consultants on the site had been reviewed.

It was stated that “there is significant uncertainty, especially in relation to the cost of the culvert if it collapses”.

It added: “Therefore, the original £2m has been transferred from the provision to an earmarked reserve, which should be retained while the risk of collapse of the culvert remains and while the site is still toxic.”