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Written Evidence submitted by Natural Resources Wales
Wales’ industrial past present us with the legacy of abandoned mine workings polluting watercourses.
Abandoned metal mines cause extensive pollution in Wales, with approximately 1,300 sites, many of which contribute to impacts on water quality and ecology in over 700 km of watercourses. Natural Resources Wales (NRW) and the Coal Authority (CA) are working together to tackle this pollution, making our rivers cleaner and healthier to benefit people, wildlife and the economy.
Over a number of years, the Welsh Government has supported NRW and The Coal Authority to work collaboratively in the delivery of a sustainable, multi-million pound national programme as part of a larger capital funded programme to address the nature and climate emergencies
The programme objective is to reduce the pollution of land and rivers from metal mines; and in so doing:
Abandoned metal mines are a major source of the metals found in our rivers, streams and lakes – metals like cadmium, lead, zinc and copper. These metals cause significant environmental damage, reducing fish populations and the diversity of invertebrate fauna, making them a high priority for national action to clean-up our rivers.
The elevated metal concentrations in rivers and streams arise from metal-rich groundwater draining from old mine workings (‘adits’ or ’levels’) and also from waste spoil heaps, tailings ponds, and contaminated sediments. Metals are leached from mining waste during heavy rains when higher river levels flow over contaminated material which can then get washed directly into the water.
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The Metal Mine Strategy for Wales, published in 2002, identified the 50 abandoned metal mines believed to be causing the greatest impact to rivers in Wales. Studies indicate that these 50 mines discharge approximately 200 tonnes of zinc, 32 tonnes of copper, 15 tonnes of lead and 600 kg of cadmium annually. Since then, site-specific investigations have prioritised and progressed remedial interventions at a number of sites including Frongoch, Cwm Rheidol and Abbey Consols.
In 2020, the Failing Waterbodies Assessment Report considered where metal mine impacts were a primary reason for waterbodies failing to achieve Water Framework
Directive (WFD) ‘Good’ status and whether or not a status change was possible following remedial interventions.
The report classified mines based on the significance of their contribution to waterbody pollution. It identified129 sites highly likely to be contributing significantly to waterbody pollution and and 140 for which more information is needed to determine their impacts.
The Metal Mines Programme was established in 2020 to continue this work. It is funded by Welsh Government and is being jointly delivered by NRW and the Coal Authority. The Programme is one of a number delivering the River Basin Management Plans (RBMPs) in Wales, which are designed to protect and improve the water environment for the benefit of people and wildlife.
The primary objective of the Programme is to achieve cleaner rivers, and in doing so, directly contribute to the sustainable management of natural resources as detailed in the Environment (Wales) Act 2016 and the Well-being of Future Generations (Wales) Act 2015.
The programme is undertaking a rolling multi-year programme of assessments and surveys of the priority sites. Every project is a long-term commitment, with several stages, needing 4-7 years from inception to delivery. Sites are assessed to identify and quantify sources of pollution, scoping and feasibility studies are conducted, alongside ecological and archaeological surveys. Where appropriate and feasible, the projects then move on to design and implementation of intervention works. We invest in research projects exploring innovative treatment solutions, including working with academic and industry experts on treatment trials at laboratory and pilot field scale.
Since 2020 we have delivered:
In addressing the water quality issues through remedial interventions, such as minewater treatlment, and surface water management such as spoil heap erosion prevention, there may also be opportunities for wider measures and enhancements to be incorporated that introduce mulptiple benefits. such as those that benefit the health and well-being of local communities, local economies and the environment. This approach is in line with NRW’s Corporate Plan to 2030 - Nature and People Thriving Together, which sets out our
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approach to tackling the climate and nature emergencies, and achieving the objectives of the Wellbeing of Future Generations Act and the Sustainable Management of Natural Resources.
The Programme also seeks to conserve, celebrate and promote the cultural heritage of mining in Wales which is often a significant part of the history of these rural areas. We continue to work with stakeholder organisations to ascertain the nature and extent of metal mine pollution in Wales, and the heritage and biodiversity value of the sites to identify suitable methods to manage any pollution impacts associated with this legacy issue
Striking a balance between the benefits of this work and potential negative environmental impacts can be challenging, and we work carefully to understand the environment of each mine and any protected species, such as bats and rare plants, to avoid any detriment and where possible conserve, enhance and improve habitats.
We are currently developing remedial strategies at our highest priority sites and where projects are sufficiently developed, we are delivering intervention works on the ground.
We currently have around 25 live projects in the programme, all at different stages of progress, some of which are considering more than 1 mine site. Most projects are initiated with the measurement of water flows, and water quality sampling, to define the problems to be solved, before moving to the consideration of possible interventions and appraisal of remediation options, followed by the development of designs. We have minewater treatment trials ongoing at two mines, and a number of projects (Abbey Consols, Esgair Mwyn, Dylife, Wemyss in 24/25) with remediation measures very close to being delivered on the ground.
More information, including case studies for ongoing and completed major remediation schemes, can be accessed at NRW’s website:Metal mine water pollution - Natural Resources Wales Citizen Space - Citizen Space (cyfoethnaturiol.cymru)
02 May 2024