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Minewater, a resource underestimated by all.

June 25th, 2020 in featured by Noreen Shears

This short piece will be sketching out and outlining several options that might be worth taking options on with regard to minewater. Such values may be where it lies in flooded workings, other values may be where it is pumped out to the surface for specific purpose or for environmental protection purposes. There are some sites where minewater requires no pumping but either trickle of erupt at the surface. There are opportunities that often agencies are blind to or too slow to grasp what is available to be made use of. These may often be laid at the door of and cited as criticism of the state regulator. This is when it is unsure of its role as regulator and in reality, would wish and enjoy the freedom to be entrepreneurial. Such clashes in culture and role can and have so far has seen many feasible and socially beneficial projects flounder about in project meetings that leave one certain that those who expound engagement are really burying them in red tape and verbiage or false difficulties.

A Little History.

Minewater has been a subject close to my heart for thirty years, just prior to the Wheel Jane, the last tin mine in Britain, minewater rebound in Cornwall over the winter of 1990/91. The environmental damage from the mine’s Nangiles Adit to the sea via the River Caron through Carrick Roads to the sea. Damage of varying intensity and economic magnitude. The knowledge base grew and by 1992 when Michael Heseltine as President of the Board of Trade announced the slimming down of the coal industry the first of our several reports on the environmental issues that were developing with not just a few mines closing down but whole coalfields, outlining the already growing pollution problems overseen by British Coal and the people who were part of the coalmining communities. This period saw not just a massive loss of water quality to many of the UK’s rivers but depression, degradation of the populations of many mining areas (The Kent mining communities saw this happen ten years previously). This was a remarkable period where Britain’s water environment saw a downturn in both water chemistry but aesthetically and ecologically.

Minewater discharged under pressure from the Nangiles Adit at rebound.

The outcome of this shrinkage of the mining industry prepared the way for the privatisation and rapid demise of the coal industry. The legislation regarding liability for pollution from abandoning mines allowed only a few years active mining to be carried out economically from 1996 when RJB Mining and Coal Investment took over the last operational mines in the country. They were the rump and as such seemed attractive. The legislation guaranteed that those companies whose mines shut prior to January 1st, 2000 could not be held liable for any pollution coming about from mine closure and the pumps that kept the mines dry being turned off. From the start of the 21st century the very few mines left in operation were not owned outright but the seams and shafts leased from the Department of Trade and Industry and licenced so as to be returned to the Coal Authority at closure. Coal Investments failed as a company soon after it had been founded and Midland Mining took over the two viable operations at Silverdale in Staffordshire and Annesley Bentinck in Nottinghamshire.

The Trust was given access to the Mine in Nottinghamshire, particularly its surface to study, carry out consultancy work on remedial work on site drainage remediation, alternative uses for the site, well studies, minewater chemistry research. We had free rein across the sites. We were able to acquaint many students from the University of Nottingham and elsewhere with a myriad of environmental issues.

At close of Annesley Bentinck on Christmas Eve 1999 we carried on looking at other energy generation options for the purchasers. We witnessed many of the options that might have had value for the site and community squandered by short-sighted council and government agencies.

Annesley Colliery headgear.

Over the period 1993 to 2000 we had carried out research on new energy issues that include gasification of coal in situ, The DTI taking us to Spain to look at the trial taking place in 1996/7 which resulted in a report and the scheme going no further in Europe. We investigated the use of wind power on the pit tips at Annesley (one is now operational there now) but a modest scheme was turned down by Nottinghamshire County Council as an inappropriate use of a mine site. A heat to energy scheme was put forward in 1996/7 when a visit to Nova Scotia took place to understand the Springhill Mine heat network was being developed from the initial Ropak minewater heat project of 1986. The Coal Authority at the time said it was not economically viable.

In 1996 a project looking at rare earths was instigated by researchers and ourselves at Camborne School of Mines looking at the recovery of rare earths that were recoverable. With the help of filter press producers, the methods were proved but it was deemed not necessary by the DTI. Lithium, and other minerals were recovered in satisfactory volumes as was native gold which carries a premium value.

The use of bacteria was researched at the same period to recover rare earths and found to work well. The bacteria had the potential to further be developed as a protein source for animals. There have been trials carried out in India during the 1990s that were brought to the UK but ceased due to the funders’ unfortunate death. We witnessed trials on sewage and mineral waste in Nottinghamshire that demonstrated the value of this technology.


Minewater across the UK costs the state millions of pounds annually. There are at present less than 100 treatment works in place currently (2020). There is an agreed schedule between the Coal Authority and Environment Agency of nearly 300 more that will bring great improvements to the environment or/and protect aquifers. There are many more that are causing minor pollution and others that are yet to be identified or classified due to uncertainties of where the need is most easily managed. There are others that are yet to make appearances due to conditions underground brought about by geological events and natural processes such as heave, subsidence, failure of stoppings. Seismic events away from mines may also have a bearing.

The UK is fortunate in many respects regarding its geology, its mineral wealth and diversity. It had the largest coal deposits of any European nation producing 300,000,000 million tons in 1913, its abundance of metals, the trade in tin was of international importance from pre-Roman times and  the country was the largest global source of copper up to near the end of the Victorian era. This wealth of minerals gave the country the greatest number of mines to be found in any nation on the planet and a legacy of pollution unrivalled across the world.

The miners left huge volumes of waste/spoil heaped up or scattered: the oldest such site at Grimes Graves the Neolithic flint mine complex in Norfolk where the unique flora still bears witness to the activities of the deep mining millennia ago. The weird landscapes formed by the Roman Scowels (iron mines) in the Forest of Dean in Gloucestershire, acidic leaching from wastes at many mines from arsenic to roadstone demonstrate both the complexity and diversity within the UKs geology.

The ongoing need to regain some part of the costs of clean up might be a pragmatic development and especially after the fiscal downturn of the world’s economies during and post the Covid pandemic. The control or treatment of mining’s historic legacies are costly and as such low-cost methodologies might be favoured as a first choice but only if they work for the long term. The possible raising of revenue stream income can be attractive but only if that funds more remedial works and is not taken a treasury income.


It is no wonder that as humankind found rocks and deposits of value from prehistory onwards at the surface where they outcropped, that they followed them down into the earth. First as just scrapes in the ground, then by adit or at deeper levels as bell pits. These workings were governed though in their depth by the water table, mining initially was a dry season undertaking following the declines in the water table. This though was not for long; drainage was to be developed that allowed miners to begin to drain areas of mining land. Soughs, leats, drainage adits were constructed draining large area of the landscape into rivers miles away. Remarkable engineering. The Great County Adit drains the  Gwennap mining district of Cornwall, it was started in the 1700s and is over 40 miles in length and drains over 100 copper and tin mines down to depths of 160 metres. The portal temperature of the outfall into the River Carnon steams in winter with water temperature over 30o C. Pumps of various forms were developed of various forms over the centuries where gravity drainage could not be deployed, Agricola in De Re Metallica (1556) outlines many such contrivances. Adits were the preferred drainage method used across the UK to drain the mining areas until pumping engines became available and allowed almost unimaginable depths to be achieved chasing the minerals deeper.

The waters pumped are not just there, they originate from several sources, rainfall, precipitation can see rises in pumping as winters deposit large volumes. Some increase is instant entering shallow level workings and flowing to those deeper, working areas and faces. Other waters precipitated longer ago gave passed through the geology and depending on the state of fracture and its speed of passing though will have picked up minerals in its makeup. This mineralisation may stain the water red with iron, acidic, some waters could rot boots of the miners. Other waters encountered were those of aquifers or pockets of groundwater, and as mines went deeper miners had to develop techniques to keep water away from the working areas as pumping was expensive.

This was achieved by the stopping off abandoned workings with impervious walls of waste material and impervious walls. These stoppings were also used to keep blocking off old and redundant workings so that the mine companies were not having to survey areas of no economic value. These stoppings in time though breach as the pressure of water being held up behind them gets too great and water entered the active area, sometime ass seeps and at others as cataclysmic floods. An event still witnessed today around the world. Stoppings today are more complex constructions with sensors and even pressure relief drainage that should allow for stoppings to last for the lifetime of the workings they are protecting. This is not though always the case.

This Plan Proved to be Inaccurate.

Today in the UK these stoppings are still affecting the movement of minewater in the abandoned coalfields. British Geological Survey and the Coal Authority planned to drain the South Nottinghamshire Coalfield via a shaft at the closed colliery at Calverton. The expected date being 2020, by 2017 it was apparent to all that this was not to be. The preparations for minewater treatment on the site at Calverton and the preparations for piping the water for discharge to Stoke Bardolph sewage treatment works went unused as the volumes of water from collieries up dip did not materialise. Stoppings placed and forgotten had held and water was building up further to the west. Annesley, Newstead, and mines towards the Derbyshire border are filling up instead. A huge potential reservoir is developing. The potential for such water will be discussed further anon.

Minewater is a remarkable catch all term for a substance of many faces and attributes. It might be a good quality water suitable for drinking water supply, the 1868 water resources of the British Isles  report by the Royal Commission on River Pollution noted many mines supplying potable supply to towns and villages across the nation direct from the mine pumping engines.  It can be highly polluting. Depending on the local geology, the speed of water inundation, the development of bacteria within the workings. It can be quite hot it is never cold, and with the right technology a long term and in many cases renewable source of low-grade energy. This might even, in exceptional circumstances be developed to power electrical generation.

Minewater does not necessarily emerge from deep underground but as a pollutant it might be the drainage build up from opencast workings and quarries, tailings impoundments and dams, spoil heaps, rock piles and now the result of fracture liquids from shale oil and gras exploration and production. It is a coverall name for any water resulting from winning minerals-based product from the earth. These last exploitative sources are currently not part of the UK’s portfolio of issues.

Minewater in the natural environment.

Minewater Heat.

The further one tunnels downward beneath the surface of the earth the warmer it becomes, this heat is ‘free’ as it emanates from the earth. The miner found in the UK and still does elsewhere find it the most gruelling part of their working underground. and as mine followed their target minerals downwards, often from outcrop or chasing pipes to find loads at ever increasingly deeper horizons.

When mines are active the atmosphere within workings needs to be controlled, gases, (methane, damp, CO) and heat together in such environments require ventilation either forced, using fans from the surface and channelled throughout the workings below ground or in some areas and not common in the post mining engine days passively using the natural drafts brought about by interlink workings and the chimney principles of flues. The heat is waste and mines whilst operational shed huge amounts. At closure, the air is expelled from many mine workings by the ingress of water from both surface and ground sources until the flood reaches an equilibrium or overtops at some level into the natural environment.

Across the Pond and into Europe.

In the 1960s some development works on using warm water were carried out at a hospital in the US. The use of warm chalybeate (iron rich) water from mines beneath the institution were accessed for therapeutic purposes. The source was then further used to heat the building. In the 1970s a Radio Shack store found a free source of heat only a few metres below their store in flooded shallow abandoned mine workings. This store used this supply of heat for several years up until the store was redeveloped in the 1980s/90s.

In 1984 a US company Ropak American Canners designed and by 1986 had installed a plant that ran heating and air conditioning using the minewater as their feed. The project was carried out at Springhill, Nova Scotia in Canada. Over the following decades the utilisation of this resource has increased to be used by many civic buildings and other companies in the area. The town’s ice hockey rink uses the heat to keep its stadium ice rink frozen. The town is proud of its unique spot in energy technology and advertises its use of minewater.

Heat during the summer months is returned to the mine from the atmosphere thus storing energy within the flooded coal workings.  This banking of low-grade heat increases the minewater energy efficiency by raisin the natural temperature by 2oC from its normal 16oC.



In the early 2000s the European Union looked to fund a project based in both Scotland and the Netherlands. A site was chosen in both countries, the one in Scotland though did not have the local authorities involved combined agreements in place intime for the start date and so the project was only centred at the site in the Netherlands, Heerlen. The Scottish part of the venture had also failed to involve the UK custodian and regulator with regard to coalmines, the Coal Authority.

The minewater energy plant at Heerlen was opened in 2010 and by 2012 the plant had managed to be fully operational. Initial problems of oxygen entering the minewater feed prior to heat stripping had caused iron hydroxide build-ups within the mechanism which choked and blocked it. This is not an uncommon outcome without experience of managing minewater as a pollutant.

There are now a growing number of similar projects being developed across Europe withs plans being developed for plants in Spain, France, Germany Slovenia, and other countries.

UK experience.

The UK is the most heavily mined nation in the world, over one third of the population live either in or adjacent to historic mining areas. It is astounding that the country has not taken the use of flooded mines to its heart. Instead there is a remarkable reticence.

Non-Ferrous Mining Areas

Ferrous Mining Areas.


Remarkably this country has installed minewater heat in social housing both in Glasgow and Fife. These projects were carried out without permission from the Coal Authority or agreeing indemnity. The Glasgow project was a small group of housing units that were built in the late 19890s, the Fife scheme was carried out in early 2000s and again a small social housing project.

The Coal Authority in the early 2000s trialled minewater heat recovery from a minewater pumping station at Dawdon in County Durham. The scheme allowed for the site laboratory to be heated. It also had teething problems with iron hydroxide blocking up the heat exchangers. It took some time to rework the method of recovering the heat prior to oxygen entering the drainage flow.

The Coal Authority has sanctioned one private minewater energy project in Sunderland. The project allows for a warehouse wine cellar to be air conditioned. The Authority’s involvement has been minimal.

The Coal Authority have announced that they are involved with several minewater energy schemes, in Wales, Glasgow, two in County Durham. These projects are reliant on European funding or private investment. On requires for half the housing to be sold prior to the development of a minewater heat network.  There are no minewater projects planned to come online in the near future though there are several that be considered ideal demonstrator site and where social gain in fuel impoverished areas might have significant beneficial effects.

The Trust has offered up several projects across the England since 1996, at Annesley, Queens Medical, Kings Mill, Nottinghamshire Police HQ, Arnold, social housing in Gedling, a University hall of residence, all in Nottinghamshire. Sites in Northumberland elsewhere where the local authorities were able to fund schemes for joint social and private occupancy homes projects.

The temperatures that the water was being pumped out of mineshafts were well above 20oC and in volumes that would have only been half utilised though others, some of the shallower seams will be cooler. The years we spent with Midland Mining, RJB Mining, Scottish Coal, Severn Trent, Thames and other water companies throughout the last decade of the 20th Century  allowed for an understanding of the viability of minewater use in many ways and for many purposes.

Reservoir Heat.

The deep mines across the country are a warm and insulated environment, many are interlinked, leaving at mine closure huge void spaces that might have been used with hindsight as productive units  and assets rather than being allowed to flood and pollute or otherwise damage the environment. Other mine systems are relatively small, both in area of mining and only working on single seams or horizons.

The Trust looked at the Selby Coalfield which is as described above. The mined area is close to Drax power station, at the time of our research Eggborough and Ferrybridge power stations were also operational. The transfer of waste heat from these power plants could have been introduced to the mine system allowing the site to gain temperatures capable of generating electricity. Currently the option no longer exists. This might be changed if a concentration of high heat shedding (data centres of similar) industries could be brought together.

Selby Coalfield.


Water Resource.

At Annesley Bentinck, the mine pumped 1.2 million gallons of water from beneath the surface to protect the active mine. The mining area itself needed to remove little water from its own workings. The water came to the surface and was impounded in a set of lagoons at a temperature of 27o C.

The shedding of this water after being brought up to a quality that could meet discharge consents to the natural environment was felt to be missing an opportunity in a country which recognises it has finite supplies.

The Water Companies.

The Trust carried out research alongside several of the England’s water companies, Severn Trent, Thames, Yorkshire, Anglian, and Northumbria. We accessed water from Longannet Colliery to Betteshanger and Redruth, and many points in between. All found waters of interest and if the development of water supply competition had gone forward as was expected many minewaters would have been utilised for industrial and potable supplies.

SmithKline Beecham,

This giant of the pharma industry commissioned the Trust to research a minewater near a site to one of their factories. The painstaking work allowed for product to be made using this water supply. It continues to be used 20 years later and a change of site ownership.


A project carried out with the NHS demonstrated minewater was an option for developing bespoke waters for the use of a major hospital in Nottinghamshire, alongside providing a heat resource. Sadly, the heat element could not be installed as a gas supply was purchased by the hospitals governing body.

Albright and Wilson.

The Trust alongside the giant of the phosphoric acid industry replaced potable supply to its power generation plant at Whitehaven in Cumbria. The supply coming from a redundant anhydrite mine close to the factory site. The economics of the venture showed a 75% cut in costs.

Mineral Processing.

The minerals tailings facilities across the metalliferous mining area of the UK were identified 30 years ago as reasonably rich in metals left as waste from stamps and shaking tables. The tailings dams in many areas are unusable due to the nature of their makeup. Cocktails of poisonous metals, cadmium, arsenic, even radioactive material in some parts of the mining country of south western England and elsewhere.

In the 1990s the Trust talked to mining companies and others about funding clean-up operations where there was the likelihood of mineral reclamation allowing the recovered metals to cover costs of bringing sites back to a productive use or at the least stopping the endless seepage of pollutants into the river systems of the area.

This kind of operation has been carried out by RJB Mining at Gedling Colliery and elsewhere, similar projects have been carried out by other companies as well. These were profitable operations in the 1990s when coal still predominated power generation. Today metals are in short supply and once many metals were mined across the UK and now prospectors are identifying rich harvests from old long abandoned facilities. Environmental clean-up comes with a price, some may be self-funding, what one wished for and others dismissed.


Rare Earths.

In 1995 we were just learning about the need for rare earths. What they were or what they looked like was a struggle to ascertain. We had completed nearly five years work looking at minewater and mine tailings. Solutions to problems and identifying new ones. Wheal Jane, Mount Wellington, St Austell, Marazion, all over Cornwall and large parts of Devon showed potential for exploitation of abandoned tailings lagoons. No one apart from a few filtration manufacturers took it seriously and even they could not understand the market as it was then.


Today there is the beginnings of a new prospecting and realisation industry. There are companies looking to exploit old tailings facilities across the UK, though the progress goes on mainly unreported.

At the End of the Day.

The use of minewater is in the hands of government and their agency. The need to cease being ‘coy’ and allowing the use of these resources should not require the Coal Authority to consider how it should make money, a government agency is not a good model for entrepreneurial endeavours. There is a need to support and encourage the private sector to move forward with sustainable use of its resources as it would if a mining company came forward to sink a non-polluting coal mine.

Author: Noreen Shears

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