Asse II mine: salt water once again being collected at the 658-metre level

On 9 March, miners at the Asse II mine took an important step towards stabilising solution collection at the 658-metre level by exposing the solution flow path in excavation 3 of the former main collection point. The flow path is therefore directly accessible. Now, the miners can once again collect the inflowing salt solution in the overall system of the former main collection point.
The experts from the BGE are now assessing whether the current provisional technical facility for collecting the solution can be replaced with a more stable system. Furthermore, collection rates at the lower levels of the mine are being monitored closely in order to assess the impact of the new situation. It will be a few weeks before one can say with any certainty whether solution collection has stabilised again.
 

• Video: Solution collection at the 658-metre level (, 30,41MB)

Several months of preparatory work

For several months now, the miners have been working their way towards the southern edge of the former main collection point. This work has been complicated and time-consuming. Among other things, gravel that had been supporting the chamber roof had to be removed, and the miners then had to secure the area with additional structures to protect people and equipment.
A few weeks ago, the miners came across a fissure in which the sound of flowing salt solution could be clearly heard. The BGE reported on this in a press release on 19 February. The miners then managed to remove the loosened salt around the fissure, expose the cavity and install a provisional setup for collecting the solution.

The current effectiveness of solution collection is demonstrated by, among other things, the fact that no solution is now reaching the borehole below the former main collection point, where it had been possible to collect a significant amount in the meantime. Over the past few months, boreholes drilled beneath the old liner had repeatedly been used as a makeshift solution to collect the salt water and therefore to limit, as far as possible, the solution’s penetration into the deeper parts of the mine. Here, it became apparent that maintaining consistent solution collection was difficult. The BGE hopes that this situation will now improve on a lasting basis.