Metal mine pollution affects around 1,500km of rivers across England and the River Nent in the North Pennines is the second worst, with high concentrations of cadmium, lead and zinc, which are toxic to fish and the insects they feed on.
Working for the Environment Agency and the Coal Authority, I&H Brown has started work on the Nent Haggs mine water treatment scheme to address this harmful legacy of the industrial revolution.
The Haggs adit, an abandoned mine water drainage tunnel at Nentsberry, discharges around three 3 tonnes of zinc a year into the river.
The water treatment scheme will remove the metals from the mine water before they get into the river. The mine water will be captured where the water comes out of the mine in Nentsberry and pumped to the treatment site through a 2.5km long underground pipeline. The metals will be removed by passing the mine water through three treatment ponds and a new wetland at West Foreshield before being put into the River Nent.
The project is expected to take around two years to build. The first phase of work between July and December will see construction of a pumping station, and the installation of the pipeline. The pumps will be housed in a new stone barn near Nentsberry, and associated improvements to the A689 surface water drains are expected to help solve some road flooding issues in this area.
Proposals for a second similar treatment scheme are being developed for the Caplecleugh adit near Nenthead to reduce pollution even further in the river, increasing the economic and environmental benefits.
The work is part of the Water & Abandoned Metal Mines (WAMM) programme which tackles water pollution caused by historical metal mining across England. The Coal Authority and Environment Agency are also working with the Tyne Rivers Trust, which is starting work this summer on more green engineering interventions to reduce contaminated waste around disused metal mines from being eroded into and polluting rivers.
Rachael Caldwell, environment manager at the Environment Agency in the northeast, 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 huge difference to the natural environment, boosting biodiversity right across the South Tyne river system, and will bring economic benefits, improving tourism and industry.
“As well as the new mine water treatment scheme, we’re working with Tyne Rivers Trust which is using natural interventions to reduce the impact from spoil heaps.
“Our rivers are the healthiest they’ve been for 20 years but further improvement is now hindered by longstanding chronic types of pollution. Therefore projects like this are playing an important role in ensuring future generations are able to enjoy our clean waters for years to come.”