Mineral-water quality drinking water directly from the mines – the water shafts at Tatabánya

The water-producing mine shafts at Tatabánya constitute the largest water base for Északdunántúli Vízmű Zrt. (the North Transdanubian Waterworks Private Limited Company, ÉDV). The water shafts provide water to some 235 thousand residents as well as the institutions and industrial facilities in 5 larger towns (Tatabánya, Tata, Oroszlány, Bicske and Kisbér) and 57 villages.

The water shafts were originally dug for the active dewatering of coal mines. In the course of mining in the Tata basin, the risk of karst water jeopardising production and the safety of miners increased to significant levels at the beginning of the 1960s. A number of medium floods occurred during mining operations. Previously, passive protection was used in the mines of the coal basin, i.e. water flowing into the shafts was collected, treated and removed.

As the coal face shifted towards less advantageous areas around the edges, passive protection was no longer sufficient to ensure the economical working of the individual areas, so active water protection was adopted in those areas. The essence of that method is that karst water is removed in a planned fashion so as to reduce the level of karst water to a depth that allows the mine to be worked while dry. For that purpose, water shaft no. XIV/A was dug to a depth of 244 metres with a diameter of 4.3 metres in the eastern part of the coal mine, along with water shaft no. XV/C, to a depth of 223 metres with a diameter of 4.8 m in the Triassic limestone of the western horst.

The water produced by the shafts could also be used to supply the regional water supply system that was built in the meantime. Although the primary objective was still the dewatering of the coal-bearing rock for the purposes of mining, they also provided a reasonably secure supply of drinking water for the water utility provider.

The situation changed fundamentally in 1985. As the mines in the basin were closed, the double function of the water shafts was discontinued, there was no longer any reason to pump out water for the purposes of mining, but the regional system, which was growing continuously, still needed a water supply. As a result, the water shafts originally dug primarily for dewatering the mines were now only used for the water supply. That was why the water shafts originally dug and operated by the Tatabánya Coal Mines Company were transferred to the management of ÉDV.

After water no longer had to be removed on account of mining, it became a challenge for the operator to remove only the required quantity of water. Maintaining the compliance of the water produced, both that used as a residential drinking water supply and the leakage water that was also obtained, and unused drinking water discharged into surface watercourses, with the prescribed values was yet another challenge. The natural and technological systems of the water base were rethought to achieve those objectives.

For more details about the developments, see: http://en.edv.ruffnet.hu/projects/