Stan rozpoznania hydrogeologicznego Centralnego Rejonu Węglowego

Abstract

THE STATE OF HYDROGEOLOGICAŁ RECOGNITION OF THE CENTRAL COAL REGION, LUBLIN COAL BASIN Summary Hydrogeological surveys of coal deposits in the area of the Central Coal Region, Lublin Coal Basin, have been carried out since 1964. The surveys have been conducted on fairly large scale but the obtained results are, however, not fully reliable, mainly because of the lack of modem recording devices. Moreover, their range cannot be treated as sufficient. The surveys and laboratory works, despite of the above mentioned shortcomings, make possible estimation of hydrogeological conditions in the Central Coal Region and they give the basis for designing and conducting mining works. The available results make possible identification of sources of water hazard for mining works, quantitative and qualitative estimations of water inflow to mines, and designing of rock massif drainage. The conducted surveys are, however, impeded by their insufficient coordination and it should be stated that their range is not adjusted to the needs of mining works. Moreover, their synthesis is still lacking. The location of the studied region within the extent of consolidated basement of the Precambrian Platform, i.e. area characterized by block tectonic and monoclinal arrangement of sedimentary rock series. This bears decisive influence on hydrogeological conditions. The only aquifers by increased water bearing and capability to fairly quick renewal here include the Quaternary and Upper Cretaceous ones, supplied throughout the area of their extent. Lower- seated aquifers, connected with stratigraphically older series, are characterized by impeded supply and drainage and, therefore, low rate of exchange of water resources. When this is the case, the capability to water accumulation is of decisive influence for magnitude of static resources in stratigraphically older series. Taking into account the nature of hydrogeological column in the Central Coal Region it may be stated that the major water hazards for mining works are connected with the following water-bearing complexes: 1) Quaternary-Upper Cretaceous (top members), 2) Lower Cretaceous-Jurassic, and 3) Carboniferous. The hazards created by the first of them concerns mine shafts only. Taking into account the results of hydrogeological surveys and the design of drainage of deposits in the Central Coal Region it may be stated that the drainage will affect aquifers related to the deposit series of the Lublin Beds (Westphalian) and Jurassic-Lower Cretaceous water-bearing complex. However, one can not exclude the possibility of local percolation of water from the Upper Cretaceous rocks as well as inflow from the Kumów Beds (Namurian), along with decrease in piezometric pressure of water in rock massif subjected to drainage. The drainage will affect aquifers situated in zone of impeded renewal of water resources. In the first stage of drainage, inflow of water to mining works will be connected with drainage of resources of static, elastic and free waters only. The prognoses of water inflow to mines in the Central Coal Region, recently made taking into account the knowledge of projects of mining and drainage, are essentially consistent with one another. Calculations made using mean values of hydrogeological parameters for individual productive units suggest inflows ranging from 11 to 20 m3/min. These figures take into account controlled rock massif drainage. Forecasted magnitudes of inflows represent mean values for a given mine. Seasonal or temporary inflows may be much higher but this is connected with insufficient knowledge •of amounts of water accumulated in fault zones. Mean mineralization of water drained from a given mine should range from 2.0 to 2.5 g/m3 and total concentration of salt in water drained from the mines will be close to 50 t per day.