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RAG Aktiengesellschaft is planning the rehabilitation and final design of the western slope of the tailings pile 1 of the former Graf Moltke 3/4 mine and coking plant in Gladbeck.
Within the western flank of the dump body, there are various fire nests and hot areas, so that special fire protection requirements have to be placed on the securing and final design of the dump, which is under mining supervision. The approximately 50 m high rising dump body is built up of washed rock material, whereby the dump was previously only backfilled without any special compaction measures. On the west side, the slopes of the dump are partly steep, up to 1 : 1.6 (slope angle of about 32°). In the course of technical stability investigations, it was determined that the existing slopes do not provide sufficient calculated stability throughout.
The primary objective of the remediation measures is the prompt fire fighting in the area of the current warm areas of the tailings pile on the western flank. To fight the fire, it is necessary to prevent oxygen from entering the dump body, which is to be achieved according to the specifications of the fire protection expert by building a mineral sealing layer on the slope flanks of the dump body. The necessary fillings on the existing dump body (sealing layers, protective layers, vegetation layers) are to be designed in such a way that the locally existing calculated stability deficits of the dump slope are also remedied in the course of the fire protection-related remediation.
The Wittringer Mühlenbach runs parallel to the western foot of the tailings pile as an open channel. Due to the small distance between the base of the tailings pile and the stream channel, the planned redevelopment of the tailings pile requires a backfilling of the stream course over a length of about 180 m as well as a temporary piping (pipeline DN 1600) of the corresponding section. In the future, the Wittringer Mühlenbach will again be routed as an open channel along the new foot of the slag heap.
The remediation activities were started in November 2022; the first implementation phase (temporary piping and backfilling of the open channel of the Wittringer Mühlenbach, construction of the seal and backfilling to the heap up to a height of about 6 m) has been completed. The actual remediation of the slag heap fire will take place in a second implementation phase, which is expected to start in November 2023.
Since 2020, TABERG Ingenieure GmbH has been working together with RAG AG and other specialist planners on the planning and implementation of the remediation of the tailings pile. The scope of work includes geotechnical investigations and consulting services (including field investigations, stability investigations of the existing slopes), the planning of the earthwork remediation of the tailings pile, including the preparation of the tender documents, as well as the support of the measure in the function of construction supervision, expert supervision and external supervision.