Drainage wells as an integral part of a deep dewatering system in Szczerców field in the Bełchatów Lignite Mine

The open-pit extraction of lignite in the Bełchatów Lignite Mine can be conducted after prior deep dewatering of the rock mass, realized with large-diameter dewatering wells distributed in the form of outer and inner barriers. This type of dewatering system allows for safe extraction of lignite, however residual waters in the overburden may locally create hazard. These are rain waters infiltrating into the rock mass, and which, due to the complicated geological structure of the deposit and disturbed system of layers, were not intaken by wells belonging to the primary dewatering system. They are removed through the existing and newly drilled exploration wells, which are converted into drainage wells. Such wells are used for removing waters suspended in permeable overburden and gravitationally moved to the lower absorbing layers, from where they are directed to the primary dewatering system wells and then to the surface water courses. The applied enhancement of the dewatering system used in the lignite deposit significantly improves the safety of mining works conducted in this place. Technical and technological aspects of drilling dewatering wells in Bełchatów Lignite Mine are discussed in this paper and followed by the evaluation of efficiency of dewatering of the overburden.