Major work to build a £9 million mine water treatment scheme that will reduce harmful metal pollution in rivers in the North East and Cumbria is nearing completion.
The Environment Agency and Coal Authority started construction on Nent Haggs Mine Water Treatment Scheme three years ago to address the polluting legacy of the industrial revolution.
The River Nent — a tributary of the River South Tyne which ultimately flows to the River Tyne and then the North Sea — is the most metal polluted river in northern England with very high concentrations of cadmium, lead and zinc — which are toxic to fish and the insects they feed on.
The River Nent only has about half of the fish and river flies expected in a non-polluted river of that kind, because the levels of harmful metals can be more than 200 times the safe level set by the Government to protect them.
The effect of metal pollution on water quality and aquatic life can be seen for 60km along the river system, with the metals accumulating in the River Tyne estuary sediments in Tyneside.
One of the most significant sources of pollution is the Haggs adit, an abandoned mine water drainage tunnel at Nentsberry.
Around three tonnes of zinc alone is discharged by the Haggs adit into the river each year.
Nent Haggs is a nature-based treatment scheme that will remove the metals from the mine water before they get into the river. The polluted water will be captured where it comes out of the mine in Nentsberry and pumped to the treatment scheme through a 2.5km long underground pipeline.
The metals will be removed by passing the polluted water through the treatment ponds and reed beds at West Foreshield before the treated water is put back into the River Nent.
The ponds contain a layer of material made of limestone, wood bark and straw in which natural bacterial reactions capture the cadmium and zinc that are polluting the river.
It is expected that when the scheme is fully operational in early 2024, it will remove over 90 per cent of these metals from the water.
The project also includes a new nature reserve, created in partnership with the Tyne Rivers Trust and Northumbrian Water Group, which provides space for wildlife and the local community.
The work is part of the Water and Abandoned Metal Mines (WAMM) Programme, which tackles water pollution caused by historical metal mining across England, and has been funded by the Department for Environment, Food and Rural Affairs (Defra). The announcement comes during the lead up to World Rivers Day on 24th September — which highlights the value of rivers and aims to increase public awareness about the threats they face and what is being done to improve them.
Dr Hugh Potter, the Environment Agency’s Water and Abandoned Metal Mine lead, said: “This project will have an immediate impact on water quality in the rivers Nent and South Tyne and in future, will help improve sediment quality in the Tyne estuary.
“It will make a vital difference to the natural environment, boosting biodiversity right across the South Tyne river and will bring economic benefits to the North East.”
