Poltegor-Instytut
Kontakt: mgr Sławomir Szymanowicz
nr tel. +48 71 348 82 64
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Creation of water reservoirs by flooding large-scale post-mining voids is one of the most commonly used methods of land reclamation associated with opencast lignite mining. The process of flooding the reservoir can take place either artificially, using surface or mine water, or naturally – through the free inflow of groundwater into the excavation. This process is constant, unceasing (lasting up to several decades) and complex. It is also characterised by a high degree of interdisciplinarity, involving issues from the fields of geology, hydrogeology, physical chemistry and geotechnics, amongst others. It also entails risks, mainly related to the stability of slopes, which is significantly influenced by the restoration of the groundwater table and the volume and nature of the inflow of these waters. Furthermore, during the filling of the excavation with water, a series of complex biological and hydrochemical processes may occur, which can determine the chemistry of the final reservoir water – a key parameter that determines the subsequent use of the reservoir, e.g. for recreational purposes.
In light of the above issues, which do not fully cover all foreseeable risks, there is an urgent need to expand existing monitoring systems and implement new ones, which will form a complementary (holistic) early-warning system for detecting risks during the flooding process.
The aim of the research project co-financed by the National Fund for Environmental Protection and Water Management, entitled ‘Monitoring of the flooding processes of post-mining reservoirs in opencast mines’, is precisely to develop a comprehensive, integrated monitoring system that will enable continuous observation of the processes occurring during the flooding process. This project proposes solutions involving the comprehensive monitoring of the flooding process of post-mining reservoirs, taking into account geotechnical, geological-engineering and hydrogeological conditions. In line with the latter, it is also planned to take into account the physicochemical parameters of groundwater and the water in the post-mining reservoir, including changes in the hydrodynamics of groundwater occurring within the rock mass and in the immediate vicinity of the flooded open-cast mine.
The project has been divided into the following stages:
- Analysis of the current condition of post-mining pits in opencast mines, a review of the scope of existing and ongoing monitoring activities in opencast mines, together with preliminary field surveys.
- Development of critical indicators in the fields of geotechnics and engineering geology, hydrogeology and water chemistry, which will be used to assess the reservoir flooding process.
- Development of a strategy and scope for monitoring flooding processes, and the principles of a cost-effective monitoring system.
- Conducting tests on a prototype monitoring system.
- Developing guidelines for monitoring the flooding of post-mining voids, depending on the prevailing geotechnical, engineering geological, hydrogeological and water chemistry conditions within them.
The final outcome of the project will be the development and testing of a low-cost prototype monitoring system under in situ conditions at a site selected during earlier stages. In addition, there are plans to produce a scientific research report in the form of a publication based on the research conducted into the methodology for monitoring the flooding of post-mining voids in opencast mines. The results of the research are also planned to be made available on a dedicated website.