RISK ASSESSMENT OF FINAL PITS DURING FLOODING

ended

The RAFF project aims to research issues related to pit lakes, which is one of the most common uses of post exploitation voids. Up to now, in Europe, there is no precedent for the creation of a pit lake of a brown coal open pit mine of the volume c.a. 1,5 billion cubic meters. There are many examples of flooded smaller final pits and in some of these, during the process of filling with water, serious geotechnical problems have been encountered. It is expected that during reclamation of open pits of volume 1,5 billion m3 the scale of geotechnical problems will be significant and may impede the process of filling the voids with water. Almost all such artificial lakes are currently (and in the future) dedicated to recreational purposes. To ensure safe utilization of these localities by the public, it is necessary to assess the risk of instability of these areas, and evaluate the long-term monitoring. The main objectives for monitoring the abandoned open-pit mines are: geotechnical stability of the close vicinity and especially the slopes (both under the water level and the final slopes around the lake); the quality of water (chemical composition), not only in the lake itself but also in the close vicinity and all water feeding into the lake. The main aims of the project are connected with the creation of comprehensive models that can be used for risk assessment purposes. Innovative outcomes of the project will contribute to methodologies and guidelines to improve the safety, security, and environment aspects of flooded open pit mines. The project will carry out in-situ investigation, laboratory tests, and numerical and physical modelling to achieve the objectives. Thirteen deliverables are planned to be developed within the RAFF project, especially methodologies, numerical models and guidelines.