This blog is written by Charlotte Adams, a hydrogeologist and Principal Research and Development Manager at the Coal Authority. Charlotte has been interested in mining impacts and opportunities for over 20 years and her work has recently featured on BBC TV programmes The One Show and Countryfile.
I have studied disused mines for most of my career. I’ve worked in different jobs, and on different types of mines, and the work has never got old. Cleaning up the environment is – and has always been – at the heart of what I do. And I do it through problem-solving: first, to understand the problem; then, to design a solution to fix it.
A fascination for old mines
I have been hooked on mines since my first geology field trip. I was fortunate to attend a school that offered GCSE Geology, taught by an inspiring and supportive teacher. For our first trip we visited the disused lead-zinc mines of Alston Moor in the North Pennines, northeast England. I was fascinated to realise that the vast mounds of rock in front of me had been moved from the underground by human hand and horsepower.
Cleaning up the past
I returned to the Alston Moor mines for my PhD, after studying chemistry and geology at university. During my undergraduate degree I worked on a project with the Environment Agency where I learnt how harmful zinc and lead mining can be. Lead, and particularly zinc, dissolve in water and are toxic to aquatic life. It made me think of the Alston Moor mines, and the water that I had seen coming out of them. Were the old mines contaminating those waters? What impact were the mines having on the river ecosystem, and the surrounding land? The waters flowed into local rivers, and potentially on into the River South Tyne, which I knew was particularly important for supporting fisheries and local water supply; how were these being affected? How might things get cleaned up? For my PhD research, I set out to resolve these questions.
The Environment Agency part-funded my PhD, which was under the guidance of the late and great Prof Paul Younger at Newcastle University. My aim was to understand the problem and develop low cost ways of removing zinc from mine water.
My first task was to identify and quantify the sources of zinc. I found multiple sources of zinc coming from the mines and calculated that the daily amount of dissolved zinc flowing downstream was equivalent to a 25cm3 cube of zinc metal (the size of a toaster!).
Having found the location, scale and source of the problem, my next step was to design and test different zinc removal options. I developed solutions that precipitated out the zinc, cleaning up the water. These systems were later successfully trialled in the field, and the findings have informed the design of mine water treatment schemes elsewhere, too. This is incredibly rewarding.
But there were more challenges to solve. Moving on from metal mines to coal mines, my next research project was in partnership with the Coal Authority. Many coal mines in the UK were closed from the 1980s onwards and, years later, new environmental problems relating to their closure were arising. When coal mines were shut, the pumps that had been used to get water out of the mines (allowing miners to get the coal), had been switched off. Groundwaters were now re-filling the mines and becoming contaminated, threatening water quality in old coal mining areas.
First we needed to understand how the mines behaved as they filled with water. We also needed to try and predict when and where these mine waters might start to pose a problem. This information could then be used to design treatment systems to deal with rising mine waters.
Connecting ideas about heat
Part of this work involved sampling water from within coal mine shafts. The waters were warm. I thought back to the abandoned lead zinc mines of my PhD. In cold weather I had been grateful for the warm air that the mines breathed out. It got me thinking… these disused coal mines, spread across the coalfields of Great Britain, were a huge heat resource. Surely there was some sort of potential here…?
My next role inched closer to the answer. I left research for industry, and worked as a consultant, assessing various water-source heat pump opportunities – including mines, rivers and groundwater. I then took up a position at Durham University to research geothermal heat and help establish the Durham Energy Institute.
Putting old mines to good use
Meanwhile, thanks to the inspirational late Jez Crooks, the Coal Authority was warming up to mine water heat. I joined the organisation in 2020, and, over a decade since those first ideas and discussions around mine water heat, I am no longer imagining ideas, I am seeing projects in action. These projects include Gateshead Council’s soon-to-be-operational mine water heat network and the planned Seaham Garden Village project led by Durham County Council.
There are over 70 mine water treatment sites across Great Britain, and these warm mine waters could be used to provide low-carbon heat to new or existing buildings in former mining areas. The Coal Authority is assessing the feasibility of mine water heat at a range of sites, and is supporting clients who are looking to drill boreholes to access mine water heat. Researchers such as David Walls (who wrote a blog for Geoscience for the Future last year) are helping to understand mine geothermal potential, too.
My job continues to solve geoscience problems and provide solutions. It’s a job that brings together and builds on everything I have done and learnt in my previous roles. I am particularly excited that my work now helps provide solutions to reduce carbon emissions, and stems from conversations over 20 years ago.
My advice to others? Don’t stop asking questions and learning. If you are passionate about something, it is important to become knowledgeable, and to keep up that learning. Things are always changing and that keeps me on my toes.