Mijnwaterproblemen in het kader van opeenvolgende mijnsluitingen

Abstract

The mine water problem is dealt with by 4 authors in 4 parts and a review. In the first part "Problem definition and preliminary studies", the study made in 1966 on the possible difficulties operating mines might expect as a result of the closing of surrounding mines, is discussed. It was evident that operating mines had to be protected from yet unforeseen water breakthroughs. In the beginning in 1968 it became known that the German Mine Gouley of the "Eschweiler Mining Co." would be closed and that in 1969 their main pumps would be shut down. The water influx of this mine was about 13 m3/minute (57 US gallons/second) with a peak of 15 m3/minute (66 US gallons/second). As there exist many underground connections between the different mines on and between both sides of the border this water was expected to flow directly across the border into the Netherlands Domanial Mine and from there, together with the water of the condemned Mines Domanial and Willem-Sophie, to other mines in the Netherlands. However, the pump capacity of the remaining Netherlands mines would be insufficient to cope with this additional water influx. After numerous discussions between the different mine owners it was recommended to proceed with the execution of project "Pump Mine Domanial". As can be seen from the drawings several water retaining dams would have to be built, to protect the mines and to collect the water of the mines Gouley, Domanial and Willem-Sophie in one basin. With the assistance of vertically submerged pumps the water level in the basin could be maintained at 310-315 metres (1030-1050 ft) below the surface level of pump shaft "Beerenbosch II". In part II the execution of project "Pump Mine Domanial" is discussed, dams were built and pumps placed. The building of one of the dams cost more than Nfl. 500,000 (US $ 140,000) due to adverse circumstances. However, had this dam not been properly built and a leak had occurred, then the drainage level to other mines would have been 100 metres (330 ft) lower, and the presently available hanging pumps would not have been able to cope with the greater depth. Furthermore additional costs for deeper pumping (Nfl. 150 000 is US $42,000) and for 5 months earlier pumping (Nfl. 250,000 is US $70,000) would have been incurred. The manner in which the dams were constructed is also discussed. Because man may never reach them again later on they had to be built as water-tight as possible. It is also explained why shaft Beerenbosch II was selected for pumping and why the vertical submersible pumps made by Ritz were chosen. The total cost for the construction of the 12 dams amounted to Nfl.2.1 million (US $600,000); for pumping equipment and auxiliaries Nn. 2.3 million (US $640,000). During the execution of project pump mine Domanial and because exploitation of Mine Willem-Sophie had to be continued, the pumping of the de activated Mines Domanial and Gouley had to be continued at a cost of Nfl. 700,000 (us $195,000). The third part discusses the geological studies of the last few years, especially the hydrogeology was intensively studied. It was concluded that as a result of the filling of the underground cavaties with water, the low pressure entry points and especially those producing brackish water, will cease to produce. It is explained why the major "Willems" fault zone could be utilized as a water barrier between the area to the south and the mines located to the north of it. In Part IV the rise of the water level in a closed mine is discussed. The rate of rise in the different mines depends on several factors, about which little is known. One had to start from assumptions, although water level measurements were carried out in one of the mines. In the review the expectation is substantiated that during the 1st quarter of 1971 a level of 170 metres (570 ft) below Amsterdam harbour level wilt be reached, with the result that "Pump Mine Domanial" will start to operate. It is concluded that it is reasonable to expect that pump mine Domanial together with the pump capacity of the still active Mine Julia will be able to protect the mines that are to be closed down in the future from water influx from the mines closed down already. It is realized, however, that there still exist 2 potential water influx locations on German territory. These are old tunnels of the mines Anna and Nordstern. How to tackle these new "discoveries" is a subject for further study.