As from 2019, the RAG Foundation will account for the defined long-term liabilities due to coal mining on the part of the RAG Corporation. In particular, those long-term liabilities can be described as follows:

Conveying mine water is essential during coal production or when the drift and shafts have to be accessed for any other reason. However, also after closure of a coal mine mine-water drainage is of great importance:

Shutting all pumps entirely down after closure of a coal mine would result in an uncontrolled rise of mine water, which could lead to:

• Methane gas being pressed to the surface at an increased pace,
• A higher risk of cave-ins due to the water rise (sudden collapse of   the surface into hollows),
• A rising surface along with the water rise,
• Saline or ferruginous waters or substances flushing out when the water runs through old working areas of a mine, contaminating the drinking water.

2. Groundwater treatment and aftercare measures

Particularly in the areas of by-product plants of RAG’s former coking plants, the soil is often highly contaminated down to the ground-water strata. Removing that soil in order to process it afterwards within treatment installations would be untenable both from a technical and economic point of view. For the most part, the contaminated soil is left in form of a hill as a so-called rearrangement structure in the respective area, water-tightly sealed in order to prevent ground waters from a possible contamination by rainwater.

Aftercare duties include measures that conduce to monitoring the redevelopment effectiveness. Rearrangement structures have to be examined at regular intervals in order to ensure that the protective layer fitted onto the contaminated soil does not lose its impermeability to water.

In addition to rearranging contaminated soil, redeveloping measures mainly focus on cleaning ground waters. Those cleaning measures protect contiguous ground-water strata from inadmissible contamination.

A further part of aftercare duties is the ground water monitoring; regular samples serve to control the ground waters’ quality.

3. Polder measures

Permanent damage due to mining subsidence is principally the effect from a surface subsidence beyond a closed mining area. Without the permanent use of ground-water pumps by associations for water management (e. g. Emschergenossenschaft / Lippeverband), the RAG Corporation and third parties, there would be water accumulations in the low grounds having arisen from mining operations.

Without the implementation of corresponding measures, a surface subsidence due to mining operations can also result in flowing waters changing their direction of flow, which would involve a water damming. In technical terms this is called deteriorated drain. For that reason, the affected waters are regularly deepened in order to rebuild the drain. Alternative to deepening the waters, river pumping stations and dikes were built in the past in order to keep the impounding water at bay. Those constructions have to be maintained on a regular basis.

Due to the subsidence of the surface, the distance between ground waters and surface also diminishes in some areas. Since this has a hampering effect on agriculture, those waters have to be pumped down as well, which leads to further permanent costs.

1. Measures of mine-water drainage Mine-water drainage takes place within the mines below ground. Water flowing, for instance, from ground-water strata or close-by mines into shafts and drift is being pumped down.