Mine water: management post-closure and lessons learned, risks from poor closure and mine water management

Abstract

Following the reprivatisation of the coal industry in the UK in 1994, the Coal Authority was formed to manage the legacy and liabilities of former nationalised coal mining on behalf of the UK government. Part of this post-mining legacy includes the pollution from the contaminated water in the mine workings. Since 1994, the Coal Authority has constructed and operated over 60 mine water remediation schemes and has implemented an evolving network of nearly 2,000 monitoring points throughout the UK. Due to the organisation’s knowledge and expertise in managing mine water and developing treatment schemes, the Coal Authority was granted permission to investigate the remediation of non-coal-related mine water pollution. Over the previous 19 years of managing coal mine water on both a local and regional scale, the Authority has gained a significant amount of knowledge and experience, highlighting a number of important examples of ‘lessons learned’ for future closing mine sites. This paper is designed to highlight some key factors and methods in understanding, developing and managing mine water pollution post-closure and other mining-associated risks. Part of the historical mining legacy in the UK is the significant problems and potential risks with regard to managing coalfields post-closure. Such issues range from lack of appropriate monitoring sites due to shaft filling, poor maintenance of old mine water drainage adits, blockages or failure of obstructions (e.g., dams) in underground workings and the risks of mine gases due to rising mine water. In addition to these issues, the Coal Authority has continually developed its systems to better manage mine waters and make future predictions in an attempt to understand and mitigate the impact of environmental issues. This paper describes how changes have been made over time to a monitoring network, along with the parameters requiring monitoring. It also uses case studies to highlight problems of previous versus current strategies to prevent aquifer pollution, treat mine water and adapt to changes in environmental regulations over time.