THGA

The question of how sustainable digitalisation can be achieved in post-mining was the focus of the symposium “Nachbergbauzeit NRW 2025 – Digitalisation meets tradition” held on 20th March 2025 at the Student Centre of the TH Georg Agricola University (THGA) in Bochum/Germany (Figure 1). Around 250 participants were able to experience in a variety of presentations and direct exchanges how much and what is already technically possible and successfully in use. The post-mining era in North Rhine-Westphalia thus built a thematic bridge from the traditional and historically immensely influential mining industry to the future and to state-of-the-art digital technologies.

Organised by the Research Center of Post-Mining (FZN) and the Department of Mining and Energy of the Arnsberg District Government, the event offered a nationally and internationally unique platform to show how digitalisation and traditional methods work together to sustainably master the challenges of post-mining.

The open and technically diverse structure of the post-mining era in North Rhine-Westphalia was addressed right at the start of the conference. In his welcome address, Prof. Christian Melchers, head of the FZN, aptly stated in line with the conference motto: “We have a treasure in the Ruhr region. And it is no longer hard coal. It is data.” Prof. ­Melchers not only emphasised the high value of geodata and the opportunities its digitalisation offers us, but also ventured a positive regional outlook for the coming decades: “The Ruhr region has the opportunity to become the greenest industrial region in the world!”

Post-mining is more than a regional issue – it is a project for the future with global relevance. Prof. Susanne Lengyel, President of the THGA, made this unmistakably clear. Her focus is on the young professionals who will help shape this change. “Together with our students and future graduates, we want to tackle the tasks that post-mining in particular brings with it,” emphasised Lengyel. For her, one thing is certain: cutting-edge research alone is not enough. We need people who are willing to take responsibility and break new ground. “The demand for raw materials is growing worldwide. We need to deal with this in a sustainable and responsible manner. These are all important issues that will occupy us today – and in the future.”

Heinrich Böckelühr, District President of the Arnsberg District Government, followed with a brief insight into the historical dimension of mining, the development of post-mining in North Rhine-Westphalia and the resulting challenges. He emphasised the importance of the Post-Mining Period in North Rhine-Westphalia, which is now taking place for the eighth time, describing it as a “genuine traditional event”. Heinrich Böckelühr also pointed out the enormous opportunities offered by digital technologies, e. g. in hazard prevention. According to the District President, the further digitalisation of the mining authority is indispensable and remains a key priority.

Bärbel Bergerhoff-Wodopia, member of the Executive Board of the RAG-Stiftung, spoke in her speech about sustainable financing and coping with perpetual obligations after the end of German coal mining. She particularly highlighted the FZN’s path to becoming a transformation centre for georesources and ecology (TGÖ). This development is a decisive step towards linking science, transfer and innovation more closely and providing forward-looking impetus for the sustainable use of georesources. Bergerhoff-Wodopia: “We are committed to supporting and accompanying the TGÖ on its journey, because we are certain that knowledge creates the basis for shaping a sustainable and liveable future!”

North Rhine-Westphalia, once an important mining region, has long since developed into a post-mining region. Today, the region uses its extensive experience and innovative knowledge to record and manage the traces of intensive raw material extraction. The symposium impressively demonstrated how historical legacy data and modern geodata can be combined to promote the sustainable management of post-mining landscapes.

The use of drones in post-mining, 3D modelling, improvements in digital maps for risk management, automation in geomonitoring, digitised water management, the use of AI and open data systems: the speakers were able to shed light on post-mining from a variety of topics and perspectives, visualise science in their presentations and explore potential.

The combination of lectures, discussions and networking opportunities, as well as the multi-perspective approach to the topic, once again proved to be a great asset to the eighth Post-Mining Period, as Prof. Melchers noted: “The Nachbergbauzeit NRW 2025 was a complete success. The concept has once again proven its worth. Comprehensive content, interesting presentations and great encounters already have me looking forward to the next Nachbergbauzeit NRW 2027.” (THGA/Si.)

We look forward to your participation in the upcoming VISION ZERO Conference, which aims to address the pressing need for responsible leadership and sustainable practices in the mining industry and beyond. This conference is organized collaboratively by ISSA Mining, THGA and RAG, BG RCI and will be held on the THGA campus in Bochum, the heart of German mining history.

Further information can be found on the event page

With the successful completion of its research phase, the EU-funded WINTER project has delivered important results for regions that are turning away from coal mining. Scientists from the Research Center of Post-Mining (FZN) at the TH Georg Agricola University (THGA) in Bochum/Germany were part of the project. They contributed to the success of the project by identifying regional governance structures in the three pilot regions of Western Macedonia, Konin and the Ruhr region and collating socio-economic aspects of structural change. They published their analyses and recommendations for action in the specially published Transition Management Handbook.

“WINTER is the first comprehensive introductory work for overarching regional management,” says project manager Julia Haske from the FZN. “This model looks at socio-economic as well as environmental changes. It integrates various local actors and structures into an overarching system. It thus provides the basis for the coordinated and effective implementation of structural change processes.”

WINTER shows how the withdrawal from coal mining affects the social and economic structures in the affected regions. The researchers have investigated the changes to employment, education and the local economy and developed recommendations to minimise the negative effects and promote positive developments.

The research results emphasise the need for careful planning for the transformation of the landscape in former coal regions (Figure 1). At the same time, they used a media analysis to investigate which accompanying communication strategies lead to greater acceptance among the regional public.

The WINTER project thus represents a pioneering model for other coal regions in Europe. The insights gained are not limited to the pilot regions, but can also be applied to other regions embarking on the path of structural change.

The lessons learnt have been published on a web platform (www.winter-project.eu). The Transition Management Handbook offers a practice-orientated guide for transition processes.

The WINTER project focussed on three specific regions: Western Macedonia in Greece, Konin in Poland and the Ruhr area in Germany. These regions offer different perspectives on the challenges and opportunities associated with the phase-out of coal mining. (THGA/Si.)

Mine water, risk management, monitoring – when mining ends, it leaves behind a variety of tasks. How to deal with them responsibly was the focus of the 21st Altbergbaukolloquium from 9th to 10th November 2023 on the grounds of the UNESCO World Heritage Site Zeche Zollverein in Essen/Germany. Around 500 experts from all over Germany came together at the site, which is steeped in industrial history, to exchange ideas in the fields of geotechnics, mine surveying, mining, geology and civil engineering. The main focus was on the important question: What will the future look like after mining? This time, the symposium was hosted by the Research Center of Post-Mining (FZN) at the TH Georg Agricola University (THGA), Bochum/Germany. “The colloquium on post-mining is one of the most important exchange formats for experts who deal with post-mining tasks and see them as an opportunity,” said Bärbel Bergerhoff-Wodopia, Member of the Board of the RAG-Stiftung, at the opening of the conference. “Scientific support for the technical processes of post-mining and well-trained specialists in this field are essential if the Ruhr region and mining areas around the world are to become regions worth living in.” “The steady decline in the extraction of fossil fuels is focussing on the phasing out of mining and the resulting tasks of the post-mining era,” added Heinrich Böckelühr, District President of the Arnsberg district government. “Examples include the planned increase in mine water in the state’s hard coal fields and the reutilisation of former mining areas for the further development of North Rhine-Westphalia as an industrial state. This also includes the expansion of geothermal energy and underground storage.” The Zollverein UNESCO World Heritage Site was therefore deliberately chosen as the venue for the conference. “It is an important landmark and identity creator for the entire region,” says Prof. Christian Melchers, Head of the FZN (Figure 1). “There are numerous opportunities here to explore the legacy of mining and develop innovative ideas for former mining regions. And for us as researchers, it is even an oversized real laboratory.” The FZN is currently carrying out several projects on the former colliery site. The colloquium’s varied programme of presentations also showed how application-oriented the current research topics are. The topics included the sustainable handling of mine water, increasing digitalisation in old and post-mining, the influence of climate change and specific remediation concepts for old shafts, spoil tips and entire industrial plants. (THGA/Si.)

The “De Re Metallica Libri XI” from the pen of the polymath Georg Agricola is rightly called the “Bible” of the miners of Europe and America. Now this special literary-scientific synthesis of the arts of the 16th century has been translated into Ukrainian. The TH Georg Agricola University (THGA), Bochum/Germany, which itself bears the name of the Chemnitz native, who is generally regarded as the “father of mineralogy” and the founder of modern geology and mining science, played a major role in the realisation (Figure 1).

Prof. Volodymyr Biletskyi (Kharkov Polytechnic Institute) and Prof. Hennadii Haiko (Igor Sikorsky Kiev Polytechnic Institute) were responsible for the comparative translation of twelve books as well as the scientific editing and commentary. In addition to the first edition, they also consulted American, Polish and Soviet editions.

Natalia Lubenska from the Research Center of Post-Mining (FZN) of the THGA also translated another component of Agricola’s first edition – namely the book “On Subterranean Beings”. “This is something special in that most international translations only include the usual twelve books – but usually omit this special section. Our translation thus comes closest to Georg Agricola’s original idea of his fundamental work,” says Lubenska.

It should be noted that the first, purely mining-related part (Books I – VI) was already published in Donetsk at the beginning of 2014. “This first edition, with certain risks, was already brought to Ukraine from the occupied city,” Lubenska tells us. The translation of the second part – sample analysis, ore enrichment, smelting, purification and separation of metals (books VII – XII) has been taking place with the financial support of the THGA since the end of 2022. The layout of the book, which should be as close as possible to the first printing from 1556, is now being created and finalised by the Ukrainian publishing house “Kyiv-Mohyla Academy”.

Lubenska is certain: “The return of Ukraine to the European family is taking place in many different ways. Our engagement on the scientific level is also part of it, including the translation of iconic works left to us by the humanists and scientists of Europe, including the books of Georg Agricola. Even Goethe once praised his work as “a wonderful gift to mankind” – now it will soon be available to all Ukrainians without a language barrier.” (THGA/Si.)

North Rhine-Westphalia is a post-mining state: intensive raw material mining has left its mark especially in the Ruhr region and the Rhenish mining area. “When mining goes, what remains are challenges such as ground movements, large opencast mining lakes, disused sites of industrial culture or the so-called eternity tasks. At the same time, however, there are also many opportunities to reshape the region,” says Prof. Christian Melchers, head of the Research Center of Post-Mining (FZN) at TH Georg Agricola University (THGA), Bochum/Germany. How to deal responsibly with the legacy of mining was the focus of the specialist conference “NACHBergbauzeit in NRW” on 30th March 2023 at the THGA (Figure 1). Under the title “Geomonitoring – on water, on land and from the air”, around 300 experts came together in Bochum to exchange innovative methods.

Because when it comes to monitoring mining impacts, a lot of high-tech comes into play: from deep-sea probes underground to special drones in the air to satellites that can make ground movements or changes in the water balance and vegetation visible. “In this way, we are also making an important contribution to better understanding climate change in detail and to sensibly designing the so-called “blue-green infrastructure” – with knowledge from post-mining,” says Prof. Melchers. In the lecture programme, the speakers addressed which monitoring methods are best suited and how they can be combined in a meaningful way.

Bärbel Bergerhoff-Wodopia, member of the board of the RAG-Stiftung and chairwoman of the THGA’s university council, addressed the students in the hall in particular in her welcoming speech: “I am particularly pleased about your participation in the conference. Your interest in the topic of post-mining is for us as the RAG-Stiftung, but also for me personally, an incentive and motivation for the many years of promotion and support of the THGA and the FZN. We will continue to need well-trained experts for the topics we are discussing at today’s conference. The fact that you have chosen to study engineering shows that you want to help shape a new, green future. When it comes to the sustainable use of geo-resources and water management in former mining regions, know-how from post-mining is immensely important and will also be in great demand in the future.”

“However, we do not only want to reach experts with our joint series of events. We have the declared goal of informing politicians, administrators and the public about issues related to post-mining in North Rhine-Westphalia and to actively involve them in ongoing discussion processes,” says Andreas Welz, Head of the Mining and Energy Department in NRW of the Arnsberg District Government, when welcoming the participants. As the competent mining authority, the Arnsberg district government is responsible for a large number of mining consequences and takes care of risk management in affected areas – in NRW alone, more than half of all municipalities have to deal with the legacy of mining.

Ralf Groß-Holtick from the city of Gronau presented a special municipal project in which many citizens were also involved: The city planning officer presented the results from the research cooperation “Monitoring Epe”, in which the FZN, the city of Gronau and the local citizens’ initiative, among others, have worked closely together over the past two years. Their common goal: the establishment of long-term and accurate monitoring in the geologically special region around Gronau.

“Salt has been mined here intensively for almost 50 years. In the process, large cavities, the so-called caverns, have been created underground,” explains Prof. Tobias Rudolph from FZN. In the meantime, natural gas, crude oil or helium is stored in most of them. Right next door is a moorland, the Amtsvenn. “This special location leads to ground movements and also repeatedly to tensions – not only in the geological structures themselves, but also between the residents, the city and the various operating companies.” The research cooperation has now provided more transparency between science and society and is to be continued in the coming years. An enduring challenge is the communication of scientific results. Especially in an environment that is often emotional due to personal involvement.

For the eighth time, the Arnsberg District Government, Department of Mining and Energy in NRW and the FZN of the THGA jointly organised the conference “NACHBergbauzeit in NRW”. The next event in the series will take place in March 2025. (THGA/Si.)

Drone pilot Bodo Bernsdorf sees the world through different eyes. When he lets his special copter soar high above the grounds of the Zollverein coking plant in Essen/Germany, he not only encounters the chimneys and pipelines at flying height – he also finds damaged areas that are not even visible to the naked eye (Figure 1). The drone’s high-resolution images reveal how the industrial monument is really doing and where remediation is needed. That is at least the theoretical approach. Bernsdorf and his team from the Research Center of Post-Mining (FZN) at the TH Georg Agricola University (THGA), Bochum/Germany, want to detect material damage without leaving any traces themselves. In the new research cooperation “KoKo Zollverein” (short for “Copter flights on the Zollverein coking plant”), the FZN is developing and testing this new methodology. To this end, the experts are working closely with the Zollverein Foundation and the Materials Science Research Department of the German Mining Museum Bochum (DBM) in Bochum. Satellite images and non-destructive lasers will also be used in the troubleshooting process. Ultimately, the aim is to carry out a detailed examination of the building fabric and damage assessment for the first time.

For more than 30 years, coke, gas and other by-products were produced at the Zollverein coking plant in Essen. During peak operation, it was considered one of the most modern coking plants in Europe. Today, the plant is an architectural monument that, together with the neighboring Zollverein coal mine, has been declared a UNESCO World Heritage Site. “In addition to the cultural play and development of Zollverein, the preservation, safeguarding and protection of the UNESCO World Heritage Site is our top priority,” says Prof. Hans-Peter Noll, Chairman of the Board of the Zollverein Foundation. “Zollverein is a place of change and the future, so it is a perfect fit that a research cooperation is now testing cutting-edge technology in this huge real laboratory, which will soon open up new possibilities for other industrial-cultural sites.”

“The Zollverein World Heritage Site is a breath-taking landmark and an important witness to industrial innovation in our region” says Prof. Tobias Rudolph, project manager at FZN. “Every time we are on site with our scientific team, we get completely new perspectives. We are now expanding that with a sensor view from above and inside.” Indeed, it’s not just the outdoor facilities that are coming under the microscope; the interiors will also be evaluated. To do this, the drones take optical, thermal and multispectral resolution images that allow conclusions to be drawn about the condition of the materials. Where can rust be found? Where is verdigris or spalling? What is the overall condition of the objects? “At best, we can visualize all of this and then make a recommendation as to where the need for renovation is most urgent,” Bernsdorf explains.

For a holistic picture, FZN experts fuse drone data with satellite images from the European Copernicus program, which provide important information about the daytime surface. In addition, they combine the information from the air with on-site measurements in which a laser scanner scans the individual objects centimeter by centimeter. “For the first time, we are thus bringing together expertise from the fields of geomonitoring and materials science at a cultural and historical site. The idea of detecting material damage by interpreting and correlating various drone-mounted sensors together in a network is thereby a completely new approach in the field of historic preservation,” explains Prof. Rudolph enthusiastically. If successfully applied, the method will be transferred to other industrial heritage sites. (THGA/Si.)

Resources are becoming scarcer, energy prices are rising. In addition, dependence on third countries has led to a global rethink when it comes to extracting raw materials. New ways must be found to extract valuable materials ecologically and economically. That these ways also follow unusual ideas is shown by a new project that has now started at the Research Center of Post-Mining (FZN) at the TH Georg Agricola University (THGA), Bochum/Germany: Over the next two years, the scientists in the “IAW3³” project will investigate whether strategic raw materials can still be extracted from mine water and which methods are best suited for this. With the help of new processing technologies, critical metals in particular are to be extracted. The experts not only look at the mine water itself, but also examine its precipitation products and treatment residues. They conduct their investigations at various mines in the Ruhr, Saar and Ibbenbüren regions.

The research project is initially funded by the RAG-Stiftung, Essen/Germany, until 2024. The full project title is: Innovative processing technologies and their potential for recovering valuable materials from mine water, precipitation products and processing residues at Ruhr, Saar and Ibbenbüren with special consideration of critical metal resources, in short: IAW3³.

“For us, post-mining does not only mean dealing with the challenges that the coal industry has left us. In the field of post-mining, it is also a matter of developing new possibilities and opportunities in the former coalfields,” says Bärbel Bergerhoff-Wodopia, Member of the Board of Executives of the RAG-Stiftung. “The new research project around the extraction of strategic raw materials from mine water is a highly exciting field of the future that is geared towards sustainability. It can contribute to reducing dependencies in raw material extraction. Just how important independence can be in this field is particularly evident to us these days. That is why we as the RAG-Stiftung are very happy to support this special project.”

“We see mine water as a potential stream of valuable materials,” says Prof. Christian Melchers, who heads the project at FZN. “The innovative thing about our idea is that we not only look at the mine water itself, but also examine the residues from treatment and its precipitation products. Precipitation refers to the separation of a dissolved substance from a solution.” What is sludge and silt for the layman is a real treasure trove for the experts at the FZN: “Recent investigations have shown that it contains, e. g., magnesium, which is used in engine construction. In the past, there have already been supply bottlenecks with the Chinese market leader. At best, we want to counteract these dependencies,” explains project member Bastian Reker (Figure 1). Rare earths, which can drive the expansion of renewable energies, or lithium, which is crucial for e-mobility, are also found.

The scientists are also examining the quantities of the critical element germanium in the mine water. “This is a by-product that is otherwise only produced during zinc extraction and is essential for the coating of fibre optic cables and thus for the expansion of the network,” says Reker. “Currently, all of these raw materials are being extracted worldwide under sometimes dubious environmental standards that affect people and the environment equally,” adds Prof. Melchers. “This simply no longer fits in with the spirit of the times and the growing ecological awareness in our society. We therefore want to initiate a rethink, accompany the processes scientifically and thus look for new possibilities on our own doorstep.”

The mine waters that are lifted from great depths with pumps in the former coalfields of the Ruhr, Saar and Ibbenbüren show a wide range of different mineralisations and enrichments – depending on the regional geology, hydrogeology and other influencing factors left behind by mining, explains expert Prof. Melchers: “We are now examining the extent to which it is also economically worthwhile to collect and process these valuable substances.”

To this end, the scientists will be setting up their own precipitation reactors at suitable locations in the coming months. In them, iron and other metals will be separated in a targeted manner by adding oxygen. They want to transfer the knowledge they gain from designing the plants on a laboratory scale to experimental plants on a large scale. In the IAW3³ project, the scientific team is also testing completely new processing technologies. Hyperspectral sensors, e. g., could help to directly detect the critical metals in mine water and co. and assess their mineralogical composition in a matter of seconds. The most promising methods are to be further developed at the FZN. (THGA/Si.)

Coldewey, W. G. (2022): Handbuch Hydrogeologie. Das Standardwerk für Lehre und Praxis. First edition. 713 pages, 104 tables, 178 figures and 42 appendices. Vulkan Verlag GmbH Essen (Figure 1).

The importance of water as a geo-resource for the people and the environment has been emphatically brought to the attention of the public in recent years. The orderly handling of water must be the focus of all professionals who are responsible for processes that influence the natural water cycle. This involves the extraction, use, purification and discharge of water, but also the protection of the public from the power of water, its retention and availability. Hydrogeology provides the basis for an understanding of the processes surrounding the geo-resource water.

The Handbook of Hydrogeology lives up to this requirement and undoubtedly offers benefit for all hydro geologically interested professionals in the sense of a standard work for teaching and practice. Thus, already when opening the book, which is widely illustrated with figures, tables and appendices, the competence of the author, who has been known for decades in wide circles as a proven expert in hydrogeology, becomes clear. Indeed, one very quickly feels literally “at home” in the topic and hardly wants to put it down.

The book is divided into the major chapters “General Hydrogeology”, “Applied Hydrogeology” and “Groundwater Characteristics”. From a scientific-technical point of view, the physical-chemical basics covered in this work are very welcome. This includes the numerous definitions of terms used throughout from standards, guidelines and guidance documents. Formula symbols are abbreviated with the letters that are also used internationally, equations are documented by figures that explain the corresponding formula designations and substantiate them with example calculations.

The present work is characterized by an extensive bibliography and a comprehensive compilation of relevant DIN standards. Literature has been compiled according to the usual citation specifications in geology, allows a good overview of the scope and facilitates the finding, even of unusual titles. The appendix contains various thematic maps from the fields of geology, hydrogeology and water management, which are very clearly illustrated in color in the form of a model landscape.

The book facilitates the user’s entry into and in-depth study of all aspects of hydrogeology through its very thoughtful and descriptive layout in terms of graphics and topics. The quality standard of the author, who has a profound experience in the field of hydrogeology, both in practice and in teaching, is evident. Both experienced professionals and young people will certainly be attracted to the work in their interest in hydrogeology. From the point of view of the depth of content, the scope and the elaborate design of the book, the price of 149 € is reasonable.

In the sense of creating transparency and understanding for the manifold questions that arise in view of the complexity of the georesource water, this standard work can be recommended for reading and use by all experts and students dealing with the subject, but also by all other interested parties.

Prof. Dr.-Ing. Peter Goerke-Mallet, Research Center of Post-Mining (FZN), TH Georg Agricola University (THGA), Bochum/Germany

Mining leaves its mark – water in particular as a resource in the former mining regions is affected by the consequences of intensive raw material extraction, some of which has been ongoing for centuries. The key issues in this year’s “NACHBergbauzeit in NRW” conference (Figure 1) looked at the challenges involving the long-term management of water and the resulting effects from the planned increase in pit water levels. The District Government of Arnsberg as the mining authority for North Rhine-Westphalia and the TH Georg Agricola University (THGA), Bochum/Germany, held the joint specialist conference for the sixth time on 10th March 2022. The 250 or so participants exchanged their professional views online on the subject of “Pit water – planned on paper, discussed online”.

In his welcoming address, Hans-Josef Vogel, District President of the District Government of Arnsberg, emphasised the vital cooperation of universities and public administration: “This innovation partnership guarantees the scientific basis for problem solving in the economy, in communities and in civil society. The research into post-mining is a very tangible example of how we can open up new vistas together, with a view to climate protection.”

Bärbel Bergerhoff-Wodopia, Member of the Board of Executives of the RAG-Stiftung, Essen/Germany, added: “In times of a recycling economy, but also with the increased use of georesources, among other things, for electric mobility, it is important to think about post-mining. For only with our post-mining experience can we succeed in using georesources sustainably today and in the future – this will only be the case if post-mining is considered right from the start in every mining process.” New ideas and innovations are needed to resolve the challenges of the future together and to unlock brand new potential.

The presentations of the conference primarily addressed the effects of the planned increase in pit water on the mining districts in North Rhine-Westphalia and in the Saarland. The speaker, Thomas Im-grund from DMT GmbH & Co. KG, explained the possible effects of rising water levels on pit gas extraction. He also estimated the overall possible impacts of the process on the emission of methane on the ground surface. He concluded with a positive outcome. With targeted extraction and utilisation of the pit gas, uncontrolled emissions would decrease considerably. The rising pit water would also cause flooding of flow paths and a lower gas output overall in the long term.

Manuela Nie and Mario Sommerhäuser from the Emschergenossenschaft/Lippeverband (EGLV), Essen/Germany, offered a very different view on the pit water. In their pre-sentation, they addressed the significance it currently has and will have on the flora, fauna and water quality in the Emscher-Lippe region. Overall, they acknowledged that the region demonstrated good ecological development. The impacts of pit water discharge are currently very low due to fast and heavy dilution in the river waters, which is perhaps why the salt concentration is well below the limit – and they continue to decrease. According to the EGLV’s plans, the whole Emscher will be completely free of pit water from September 2022.

The presentations in the second part of the event covered the challenges faced regarding the responsible handling of PCBs. This abbreviation stands for polychlorinated biphenyls; chemical chlorine compounds which were used in the coal mining industry, e. g., in hydraulic systems, transformers and gearboxes. The fact that PCBs are potentially harmful to human health and the environment was not known for some time. The use of this substance was not forbidden until the mid 1980s – traces can still be detected in pit water today, albeit in very low levels.

In his speech, Michael Denneborg presented a report commissioned by the North Rhine-Westphalian regional government to assess possible risks for ground waters and surface waters. In it, the qualified geologist from ahu GmbH, Aachen/Germany, looked at the possible effects of rising pit water on the discharge of PCB and other residual materials. His conclusion: Overall, higher pit water levels reduced the flow of PCB and the pit water volume in bodies of water over the long term.

Following this, Joachim Löchte from RAG Aktiengesellschaft, Essen/Germany, presented the intensive monitoring programmes developed by the company in order to constantly check and systematically record the flow of PCB into pit water. He covered the technical challenges faced during monitoring in particular. He also presented current projects the RAG is working on, with scientific support from the Research Center for Post-Mining (FZN) at the THGA, with the aim of further minimising contaminants, e. g., using special filters and treatment plants.
(Carmen Tomlik (THGA)/Si.)