New Lagoon

Former mine lagoons in the Lake District are being used for a pioneering clean-up operation being led by Newcastle University.

A new £1m scheme to clean-up metal pollution being discharged into our rivers from old mine workings is being piloted in the heart of the Lake District National Park.

The ‘vertical flow pond’, designed by experts at Newcastle University on behalf of The Coal Authority, is the first of its kind in the UK and uses compost and limestone to treat metal-rich mine water.

Work has begun at the site of the former lagoons at Force Crag mine outside Keswick, with the aim of removing the three tonnes of zinc, cadmium and lead which is being discharged every year into Bassenthwaite Lake.

Funded by Defra, the project has four partners - The Coal Authority, Environment Agency, The National Trust and Newcastle University.

The Coal Authority starts construction this month and aims to have the two ponds up and running by early next year. If successful, this technology could be implemented at other mine sites across the country.

“Currently, three tonnes of metal is discharged from the mine every year and pollutes not only the nearby becks, but is also being transported downstream and polluting the lake,” explains Dr Adam Jarvis, a Reader in Environmental Engineering at Newcastle University.

“What we have developed is a passive treatment method which removes the metal from the water without the need for energy or chemicals. The aim of the pilot is to test the effectiveness of this new technology on a large scale.”

Environment Minister Richard Benyon said: “This cutting edge pilot is a great way to reduce water pollution from the mine without the need for chemicals. It is also a good example of different organisations working together to improve local water quality.”

The project is supported by a £1 million government fund set up to combat water pollution caused by metal mines across England. Reducing water pollution from Force Crag mine will bring real benefits to the environment and local economy.

The £1m cost includes the preparatory work, installation of the plant and the ongoing maintenance costs. Ultimately, the aim is to treat the pollution of more than 4,000km of rivers in England.

Dr Hugh Potter, the Environment Agency’s national lead for abandoned mines, adds: “This large pilot scheme is the culmination of many years work to identify cost-effective solutions to this longstanding pollution issue.

“We need to clean up hundreds of abandoned metal mines across England, and hope that the partnership at Force Crag will pave the way for other schemes.”

“Water discharges from abandoned mines such as Force Crag are environmental legacies of our past and need to be addressed if we are to improve failing water quality in the UK,” explains John Malley, Water Advisor for the National Trust in the North West.

“DEFRA are to be applauded for their initiative in backing this, as are English Heritage, for accommodating a treatment system on the site of an ancient monument. Improving the Bassenthwaite catchment area will ultimately support the conservation of our natural diversity, as well as providing clear, clean water.”

Steve Hill, Principal Technical Adviser of the Coal Authority, said: “The Coal Authority’s experience in remediating mine water pollution from coal mines will be used in this innovative solution to treat the polluting water discharge from former Force Crag mine.

“I believe this large scale pilot scheme will bring environmental benefits to the watercourse in the area and will lead to other metal mine sites throughout Britain being remediated in the future.

“It should be acknowledged that the focus and commitment of all the stakeholders has been instrumental in bringing this scheme to fruition.”

How a vertical flow pond works

One of the key features of the project is that it will breathe new life into the former mine lagoons.
Traditionally used to store waste, or ‘tailings’, the lagoons were a polluting but important part of the metal mining process.

The aim is to excavate these lagoons and use this material to construct the bunds of the proposed ponds which will be filled with compost and limestone to create the vertical flow pond system.

Water discharging from an old mine entrance will be re-routed through an underground pipe and fed into the top of the ponds.

The metal-rich mine water then flows down through the compost mix and metal pollutants are removed from the water.

Finally, the clean water flows into a wetland area planted with rushes which will filter out solids before the water is released back into Coledale Beck.

published on: 3 October 2013