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Glückauf! 3/2019

Water plays a critical role in the mining industry and this will apply in the post-mining era just as much as it did during the production years. When a mine is in operation the main concern – for both underground and opencast workings – is to ensure that the mining area is kept free of water in order to create a safe and properly functioning environment. These dewatering operations are mainly in the interest of the mine operators. However this situation changes when the production phase ceases and there is growing public interest in what is to happen with the former mining site. The issues that arise in this context mainly have to do with the impact of mine water on the groundwater bodies, the flooding of residual opencast mining cavities, the restoration of residual lakes and, essentially, the treatment of mine water with a view to preventing pollution and contamination.
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With my best regards // Mit freundlichem Glückauf
Dipl.-Ing. Andreas-Peter Sitte
Chief Editor Mining Report Glückauf, Essen

ISSUE 03/2019

Mine Water in the Ruhr Area – Opportunities for the Future

Fig. 1. Mine water discharge points 2006 in the Ruhr area. // Bild 1. Grubenwassereinleitungen 2006 im Ruhrgebiet. Source/Quelle: RAG

With the end of German hard coal mining in 2018 the dewatering of the mine working is, from a technical point of view, not necessary any more. Therefore new options arise to redesign the mine water management in the post-mining future. The mine water conception of RAG Aktiengesellschaft, Essen/Germany, includes a reduction of the number of dewatering stations, their conversion into well-operated pumping stations and the rebound of the mine water level. Especially with regard to the discharge into streams there is the chance to keep numerous rivers and their tributaries free of mine water. In the Ruhr coalfield, only six out of currently ten dewatering stations are supposed to stay in operation.

Authors: Isabelle Balzer M. Sc., Dipl.-Geol. Markus Roth, RAG Aktiengesellschaft, Essen

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Tunnel Construction meets Underground Mining – Special Technical Challenges in Development and Planning of the Mine Water Sewer Ibbenbüren

According to political guidelines the withdrawal from the coal production in Germany took place at the end of 2018 and with this the retreat from the mine site Ibbenbüren of RAG Anthrazit Ibbenbüren GmbH is currently being carried out. In order to fulfil the purpose of eternity of the mine water draining and to reduce operating costs in the long term, the rising mine water is to be captured safely at a defined level and permanently fed to a water treatment system by gravity. In order to fulfil this task a new about 7.3 km long mine water sewer has been projected. In the late summer of 2018, the working group mine water sewer Ibbenbüren, consisting of the German engineering offices Dorsch International Consultants GmbH, Offenbach, IMM Maidl & Maidl Beratende Ingenieure GmbH & Co. KG, Bochum, and Dr. Pecher AG, Erkrath, was commissioned to carry out the planning services for the mine water sewer.

Authors: Dipl.-Ing. Dennis Edelhoff MBA, IMM Maidl & Maidl Beratende Ingenieure GmbH & Co. KG, Bochum, Dipl.-Ing. Jürgen Kunz und Dipl.-Ing. Heinz-Dieter Pollmann, RAG Anthrazit Ibbenbüren GmbH

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Protecting Aquifers from Rising Mine Waters: Managing Mine Water in the Durham Coalfield (UK) and a Comparison with Methods used in Lorraine (France)

Fig. 2. South Butterknowle region of the Durham coalfield. The black lines indicate the limits of the different mining blocks (according to (9, 11)). The entire area was closed down, and subsequently flooded, during the 1970s. This flooding operation resulted in some local impairment of the overlying Magnesian Limestone aquifer, as verified at observation well NCB22 (7, 8, 9).

When a coalfield finally ceases production there will no longer be any operational requirement to continue with the mine pumping and dewatering operations. Switching off the pumps generally results in an increase in mine-water levels. This process can take place very quickly or may even last several years or decades. Rising mine-water levels are an ongoing event in many places, not only in Germany but around the world, and the public is sometimes completely unaware that they are happening. In the former mining area of South Butterknowle in the Durham coalfield (United Kingdom) an inaccurate assessment of the hydrogeological conditions resulted in mine water and groundwater being mixed together. This paper will seek to show how lessons can be drawn from the Durham experience and how the mine-water management procedures adopted during the post-mining phase in the East of Wear (UK) and Lorraine (France) mining areas can be adapted with a view to providing long-term protection for the aquifers in these regions.

Authors: Dr. rer. nat. Bastian Reker, Sebastian Westermann M. Sc., Prof. Dr.-Ing. Peter Goerke-Mallet, Prof. Dr. rer. nat. Christian Melchers, Forschungszentrum Nachbergbau, Technische Hochschule Georg Agricola (THGA), Bochum

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Restoration of Groundwater Levels in the Rhineland Lignite Basin

When an opencast lignite mine is closed the artificially lowered groundwater essentially has to be restored to its pre-mining level as quickly as possible. This means taking account not only of the impact that mining operations have had on the water landscape but also of any local infrastructural features and housing developments. The various hydrological problems and responsibilities associated with such an operation are presented and discussed below from the perspective of the Rhineland lignite mining area. This paper is an updated version of an article of the same title that was published in Wasserwirtschaft (no. 4, 2017).

Authors: Prof. Dr.-Ing. Christian Forkel, Sara Hassel M. Sc., Dr.-Ing. Piercristian Rinaldi, Dipl.-Ing. Christian Müller, RWE Power AG, Bergheim

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Flooding Operations in the Lausitz Area in 2018: an LMBV Report

For the Lausitzer und Mitteldeutsche Bergbau-Verwaltungsgesellschaft mbH (LMBV), Senftenberg/Germany, 2018 was marked by a wide range of activities focused around the planning and implementation of restoration and redevelopment measures, this work being particularly affected by the extreme dry weather, which had an impact on the remediation efforts and on the management of water resources in the Lausitz lignite basin. 2018 was the first year that more water was drawn off from the recently completed LMBV-managed residual lakes and storage ponds than from the region’s river basins. The situation in the residual lakes, where geotechnically prescribed water limits were reached in the Lausitz area, was successfully kept under control by means of an active management regime. The only incident occurred at the Senftenberg public lake where the low water levels caused some slippage on the island. During 2018 work in the Lausitz area continued to focus on developing a hydrological regime that would be as self-regulating as possible. The water deficit in the region, with the catchment areas of the Spree, Schwarze Elster and Neisse rivers, fell slightly …

Authors: Dipl.-Ing. Eckhard Scholz, Dipl.- Ing. Doris Mischke, und Dr. Uwe Steinhuber, Lausitzer und Mitteldeutsche Bergbau-Verwaltungsgesellschaft mbH (LMBV), Senftenberg

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Understanding of Hydrogeochemical Systems – Findings on Inflow Systems of Opencast Ore Mines and on the Recovery of Valuable Elements from -Tailings or Mine Waters

Fig. 2. Field investigation and sampling of a Chilean tailings body. // Bild 2. Felduntersuchung und Probenahme an einem chilenischen Tailingskörper. Source/Quelle: TUBAF

Mining is not possible without consideration of the component water. This is coupled to a variety of questions. These include, e. g., dewatering in underground and open-cast/pit mining, the post-mining flooding of open-cast/pit residual holes, the remediation of acidic post-mining lakes, general management and treatment of such acid waters (Acid Mine Drainage – AMD) etc. In relation to the above-mentioned aspects, but also for the re-mining of secondary mining bodies (tailings), it is essential to gain a detailed process and structural understanding of the respective site.

Uncontrolled water influxes into open pit mines impair the efficiency of ore extraction and production conditions. Therefore, it is important to understand the inflow system, to detect the sources of these water influxes and so to initiate targeted and effective dewatering measures. The detailed hydrogeochemical investigations of the water inflows and of the potential …

Authors: Juliane Günther M. Sc., Dipl.-Ing. David Hagedorn, Dipl.-Geoök. Maria Ussath, Dipl.-Ing. Marlies Grimmer und Dr.-Ing. Nils Hoth, Institut für Bergbau und Spezialtiefbau, Technische Universität Bergakademie Freiberg, Freiberg

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Why Underground pumped Hydro Storage Plants despite their Broad Advantages are not built?

As the share of energy generation from intermittent renewable sources increases, energy storages become more important. Among various direct and indirect power storage technologies, pumped hydro storage power plants are known as the only proven large-scale storage technology for more than a century. Pumped hydro storage power plants have many advantages: They have a long service life, can store energy over several hours or days, and have relatively low specific costs compared to other storage technologies. Nonetheless, pumped hydro storage power plants use large areas of land and people are often hostile to new projects. A solution to these problems are underground pumped hydro power plants.

Authors: Dr. Maik Günther und Dr. Christoph Rapp, Stadtwerke München GmbH, München, Mostafa Fallahnejad M.Sc., Technische Universität Wien/Österreich

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Making Homes where Collieries once stood

Fig. 4. The “An der Geißwies” residential estate in the Saarland town of Friedrichsthal has given RAG Montan Immobilien an opportunity to showcase its competence as a developer of family housing projects. The site holds 60 individual plots that are to be developed in two phases. Phase one comprises 36 properties, almost all of which have now been placed on the market. Photo: RAG MI, Thomas Stachelhaus

The Essen-based company RAG Montan Immobilien GmbH is currently responsible for the management and development of some 8,750 ha of land comprising its own property portfolio along with real estate owned by the RAG Aktiengesellschaft. Since its founding the company has revitalised another 9,260 ha of former mining land and has developed these locations for various uses, ranging from industrial estates and technology parks, new office locations and residential quarters through to logistics centres and leisure parks. Thousands of jobs and homes too for several thousand people have now been created on these sites, some of which had previously been home to heavy industrial operations. RAG Montan Immobilien has also been focusing efforts on projects associated with the use and generation of renewable energy, this including solar radiation, spoil-tip wind and biomass, which can be used to produce electricity and heat energy.

Author: Stephan Conrad, RAG Montan Immobilien GmbH, Essen

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Site Restoration and Compensation and Replacement Measures in the Lausitz Coalfield

Fig. 1. Selection of major projects now ongoing. // Bild 1. Ausgewählte Großprojekte. Source/Quelle: LEAG

One in every two hectares of restored former lignite mining land in Germany is to be found in the Lausitz area, a testament to the skills of mining and restoration specialists. And the active mining industry, in the shape of the current Lausitz Energie Bergbau AG (LEAG), Cottbus/Germany, has played a key part in this work. The company’s remit is to extract and process the indigenous resource and to ensure rehabilitation and recultivation of the landscape after mining operations have ceased. In the course of the last two decades the LEAG has restored nearly 6,900 ha to arable use. Any attempt at compensating for an industrial incursion into the natural environment must ensure that the affected land is restored in as effective a way as possible – which means shaping a sustainable, economically viable and secure post-mining environment.

Author: Dipl.-Ing. Thomas Penk, Lausitz Energie Bergbau AG (LEAG), Cottbus

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