Operational foundations

• Operational foundations

  The open-cast mine prepares the ground for recultivation itself. Suitable substrates are cleanly separated from the rock and transported to the back of the open-cast mine using conveyors. Spreaders first tip clay, sand and gravel into the excavated areas in order to refill the open-cast mine. They then place a drainage layer made of water-permeable material on top. Nowadays, slopes and troughs are designed to look as natural as possible, which means that they are as irregular as nature itself. In areas where reforestation is planned, a mixture of loessic loam and gravel is applied as the top layer of soil, which is known as soil for woodland restoration (Forstkies). This material is loose enough for the roots of the trees to penetrate deep into the soil. It is also loamy enough to store plenty of water for drier seasons.

  Areas recultivated with soil for woodland restoration are no longer levelled, instead they are either left as they are or carefully flattened without the areas being driven over in order to avoid compaction, and thus waterlogging and erosion, and to take advantage of the microclimatic benefits of tipping ridges and small troughs. In areas where new farmland is to be developed, spreaders apply pure loess and loessic loam. The same goes for areas to be afforested in the plane. This layer must be at least two metres thick following some subsidence. Then the loess is carefully flattened. Water areas and periodically wet locations are another element of recultivation. Lakes can now be found in recultivated landscapes; large water bodies are also planned for the residual mining holes of current open-cast mines due to the mass deficit to be expected after coal mining. 

• Open-cast mining and cultivated landscapes

  Lignite can only be extracted from open-cast mines. This means that mining has a sizeable impact on the densely populated cultivated landscape.

  Open-cast lignite mines are located in cultivated landscapes that are subject to intensive use at all times. They are the commuter belt for the cities of Cologne, Aachen, Mönchengladbach and Düsseldorf and are therefore densely populated.

  Transport systems and urbanisation have fundamentally changed the composition of this previously agricultural and now intensively used region. As the soils are also among the best in Germany, they are predominantly used for agricultural purposes.

  Open-cast mines encroach on this cultivated landscape. The natural landscape is currently a thing of the past in places where overlying rock is removed and lignite is extracted. Due to the layers of loose soil, raw materials cannot be extracted underground in the Rhineland, as they are in the collieries in the nearby Ruhr region. Lignite in the Rhine region has to can be extracted from open-cast mines.

  The impact of these is only temporary, however. The main features of the post-mining landscape are determined during the approval procedure for an open-cast mine. Planning of the new landscape also starts at this early stage. As soon as the first sections of a coal bed have been extracted, recultivation work begins to restore arable land, forest and other areas.

• Recultivation begins before open-cast mining

  Regulatory approval procedures build the framework for planning the landscape later on. How RWE Power shapes the land once open-cast mining has ceased is always determined by regulatory proceedings. Decisions regarding the appearance or character of the future new landscape are made when the planning permission for an open-cast mine is first received.

  These include initial specifications as to the division of areas for agriculture, forestry, settlements and other uses.

  These specifications are progressively and promptly fleshed out in further operational planning processes until they are ready to be implemented. During these processes, farmers, foresters, conservationists, transport planners, business developers and many others present their interests. Conflict is part and parcel of this process. Generally speaking, each public body represents legitimate interests and has its own views on possible future uses. New arable areas protect agricultural companies as well as their families and livelihoods, and municipalities expect new commercial areas to provide economic impetus, i.e. jobs and revenue. New woodland areas, meadows and lakes are welcome recreational areas.

  Experts from authorities, associations, science and mining agree on key issues: Recultivation is not an attempt to recreate nature. Humans can only give it a jump start by creating the best possible conditions for a sustainably used landscape. The compromises to be reached are not temporary solutions. It is not the separation but rather the interlinking of uses that can reconcile the interests of economy and ecology on a sustained basis.

• Natural conditions

  The Lower Rhine Embayment is an area subject to intensive agricultural use. This is because its soils have a high yield potential. The parent rock of the weathering and soil development processes, lasting for thousands of years, is ice-age loess. The geologically youngest loess (Weichselian loess) and the soils resulting from it determine the high value of these arable lands.

  The soils produced by the Weichselian loess form the uppermost layer of the earth’s crust in large parts of the Lower Rhine Embayment. Luvisols have primarily been created, which can be more or less strongly eroded depending on the shape of the terrain.

  This soil can store a great deal of water thanks to its high silt content of 70% to 80%. This means that agricultural crops can even withstand summers with very little rain without sustaining significant yield losses.

  The soils of the Lower Rhine Embayment are among the most fertile and best sites in the world. The high yield capacity of the old land soils entails a high level of responsibility for the production process of what are known as new land soils. Proper use of the loess produced at the surface is key to achieving a high yield. 

• The history of recultivation

  Recultivation in the lignite mining areas of the Rhineland has a long tradition. Initial restrictions and requests for recultivation stretch far back into the past. In 1766, a lease agreement for Roddergrube stipulated that the pit left behind had to be reforested with alders. It was not a question of the landscape or even ecological requirements, instead it was economically motivated: Woodland was an important commodity.

  The General Mining Act for Prussia (1865) one century later stipulated that restoration be professionally monitored. Mining authorities supervised the design and use of surfaces by the mining companies once lignite mining had ceased.

  At the turn of the century, lignite mining had reached industrial proportions. More emphasis was placed on making the excavated areas fit for economic purposes again. In a ‘mining police regulation’ in 1929, the mining authorities in Bonn enacted the following: “In view of open-cast lignite mining, all spoils must be put back into the depleted open-cast mines in order to create the largest possible areas for agricultural and forestry use.”

  Up until World War Two, restoration efforts were rightly directed at creating new woodland. At the time, lignite mining was mainly carried out on the wooded Ville ridge between Bonn and Cologne.

  It was only when open-cast mining moved northwards up to the important arable areas of the Lower Rhine Embayment that restoration requirements changed. In the 1960s, the Loess Agreement was signed, which stipulated that fertile loess had to be used for recultivation. Achieving qualities in recultivation that farmers could recognise from their developed soils is only possible with this loess.

  Starting in the late 1950s, technical and biological advances brought about the mechanisation and intensification of agriculture, which continues to this day. The initial focus was on the greatest possible production of food. In recent times, agro-ecological issues have become increasingly important. Environmental sustainability, a much-cited buzzword, is particularly important for agriculture. Ultimately, agricultural activity is exclusively based on natural resources. Modern agriculture cannot succeed if it goes against nature, rather it can only succeed if it works with it.

  More challenging crops have highlighted just how fragile agricultural production and exploitation systems are. This has also been seen in extensive recultivation areas: In cases where the treatment of the loess lacked the necessary care, the crops were not able to reach the desired yields. In the early 1980s, criticism of new land managers led to a comprehensive programme of scientific studies and soil improvement. The findings of such have helped to advance recultivation technology and improve land management. This made it possible for the objective dictated by nature and expected by the farmer to be achieved.

  Increased environmental awareness, the need to reform the European agricultural market and, last but not least, the social needs of farming families are now leading to higher standards being set. Agricultural areas are no longer seen as just a production factor, but rather as an important part of the landscape. The recultivated meadows must also offer recreational space and protect nature and species. The current state of recultivation is shaped by the combination of all disciplines and a holistic approach.

• The production process

  The abundant loess in the Rhineland has been key to the success of recultivation. It is handled with the appropriate care.

  The open-cast mine prepares the ground for recultivation itself. Spreaders first tip clay, sand and gravel into the excavated areas and then place a drainage layer made of water-permeable material over the top. Nowadays, slopes and troughs are designed to look as natural as possible, which means that they are as irregular as nature itself.

  In areas where reforestation is planned, a mixture of loessic loam and gravel is applied as the top layer of soil, which is known as soil for woodland restoration. This material is loose enough for the roots of the trees to penetrate deep into the soil. It is also loamy enough to store sufficient quantities of water for drier seasons. Areas recultivated with soil for woodland restoration are no longer levelled in order to avoid compaction, and thus waterlogging and erosion, and to take advantage of the microclimatic benefits of tipping ridges and small troughs.

  In areas where new farmland is to be developed, spreaders apply pure loess and loessic loam. The same goes for areas to be afforested in the plane. This layer must be at least two metres thick following some subsidence. Then the loess is carefully flattened. Water areas and periodically wet locations are another part of recultivation. Lakes can now be found in the residual mining holes of the old open-cast mines; large water bodies are also planned for the residual holes of current open-cast mines due to the mass deficit to be expected after coal mining.

• Land transfer/consolidation

  In a mine transfer agreement concluded between owners and mine operators, the modalities of compensation or transfer in the form of recultivated new land are regulated in the run-up to the land being used. The land is transferred by a public authority as part of a land consolidation process.

  This involves arable areas used for mining purposes being exchanged for newly recultivated arable land. The exchange ratio for the transfer of areas no longer used for mining purposes is determined on the basis of soil quality (viability) of the old land and the new land. Once the recultivation process has been completed, the new land soils are re-assessed (inspected) by an independent assessment board (delegation of experts). The assessment of the new land soils forms the basis for the exchange ratio. To compensate for uncertainties in the yield assumptions and soil development, RWE Power grants a ten percent premium on the exchange based on yield measurement figures in accordance with the warranty agreements for new land soils agreed between Rheinischer Landwirtschafts-Verband e.V. and RWE Power.

• The outcome

  Recultivation in the Rhineland is not only considered exemplary by experts around the world.

  The recultivation methods have been continuously improved as part of a long learning process. Over the decades, they have been adapted again and again to modified objectives and new scientific findings.

  There is still much to be learned. Scientific work carried out by university institutes supports recultivation efforts and contributes to the work done in and around the new landscape. RWE Power has set up a recultivation research centre (in German) in Jüchen. It provides scientists with a contact point, library and laboratory for their work. So far, international experts have exchanged their findings and experience at two recultivation conferences at the invitation of RWE Power.

  High-quality recultivation is important because the new landscape must not only provide temporary compensation and balance, it also needs to be fit for various purposes and sustainable use in the long term – as economic and living space for many generations to come.

  The open-cast mines in the Rhineland have used up around 290 square kilometres of land to date, of which approximately 200 square kilometres have now been restored. Some 103 square kilometres are arable land, 77 square kilometres woodland and 20 square kilometres water and other areas. 

• Outlook

  Although a great deal of progress and success has been achieved over the decades, there is still much to be learned in recultivation. The experts at RWE Power are open to all possible avenues. Findings, whether from our own work, university research or the exchange of experience at expert conferences organised by RWE Power, are incorporated into the day-to-day operations of the responsible specialist department and help to advance recultivation. Nothing is so good that it cannot be improved further.

  Recultivation research has three objectives: Firstly, it aims to document the development of new landscape areas and highlight areas that require help and support. Secondly, it aims to examine environmental effectiveness. A study revealed that tipping without levelling in forest areas, which is common these days, increases biodiversity later on and promotes the growth of important tree species. Thirdly, research generates ideas for improving recultivation, such as planting and propagation of native shrubs and trees. Today, RWE Power grows plants for the new land from the seeds of the old forest or takes hay from protected meadows and sows new areas with native wild plants, thereby preserving genetic diversity – an element of biodiversity.

  Recultivation remains a learning process for everyone involved. The more experts are intensively involved in the process, the better the outcome. The goal remains ambitious: to reintegrate the landscape used for mining into the rest of the cultivated area so that it can be used in a versatile and environmentally friendly way, leaving all options for the future open to future generations. 

Recultivating former mines

• Habitats and economic areas for many generations to come

  The recultivation of former mines is of prime importance to RWE. The company has acquired decades of experience in this area and is constantly working to improve recultivation strategies with research institutes, universities and independent experts from the fields of environmental protection, forestry and agriculture. 

• Return of an ecologically intact landscape approved

  Specialist authorities, the affected communities and the agriculture and forestry sector work together with the experts from RWE Power to create the plans for the recultivation of former mining areas. They all register their interests, which then have to be reconciled by the approving authority. We then make the plans a reality. All mining plans begin with the binding approval of the endpoint of the process – the return of an ecologically intact landscape. In many cases, the mine operator has, by the time that mining has ceased, created a major advantage for the forests and bodies of water, the landscape diversity and the biodiversity of the area. 

• Exemplary recultivation in the Rhenish coalfields

  It is important to note that recultivation is not an attempt to recreate nature. Humans can only provide the impetus – nature itself has to do most of the work. The recultivation of the Rhenish coalfields is seen by experts worldwide as exemplary. One example is the diversion of a five-kilometre stretch of the river Inde in the district of Düren. Just a few kilometres away is the Inden mine: in the summer of 2005, it reached a five-kilometre section of what used to be the Inde riverbed. The river now leaves its old riverbed at Lamersdorf and freely flows for around twelve kilometres through a new river meadow that is up to 300 metres wide and located in the mine recultivation zone. Within a largely forested lowland, it can meander freely here before returning to its old levelled riverbed near Kirchberg. 

• Close partnership with German universities

  For many years, scientists from German universities have been working together closely with the recultivation experts at RWE Power AG. To aid this cooperation, RWE Power AG set up the “Forschungsstelle Rekultivierung” (Recultivation Research Post) in Elsdorf. It serves as a point of contact, library and laboratory for the researchers’ studies. At two recultivation conferences hosted by RWE Power AG so far, international experts have been able to exchange their findings and experiences.