Spiral drift blocked on 637-m level
In the Asse II mine, the Federal Office for Radiation Protection (BfS) blocked the spiral drift below and above the road junction in a depth of 637 m as a preventive measure. The spiral drift is the road connecting the levels between the 490-m and 750-m levels.
Experts of the Asse-GmbH had pointed out that the roof over the roadway crossing was damaged up to a depth of two metres. Therefore, the Asse-GmbH secured the area with three-metre-long anchors. Since the workers detected another, about four-metre-deep crack in this process, further examinations were carried out. These examinations showed that the rock was strongly damaged between the upper and lower section of the spiral drift (up to 20-cm-wide cracks). Remediation works will take several months. The spiral drift is therefore available to a limited extent only for a longer period of time. It is currently also considered to newly construct a corresponding section of the spiral drift.
The mine areas lying underneath this spiral drift can meanwhile be accessed via the shaft hoisting plant. Since it cannot be excluded in the event of an emergency, for example in case of a fire, that the road to one of the two levels (490-m level, 750-m level) providing access to the shafts will be blocked, a so-called emergency drilling was made which bypasses the damaged part of the spiral drift.
Update of 29 June 2012
The blocking of the spiral drift is a safety measure of the Asse-GmbH to protect the staff. This procedure has been co-ordinated with the State Mining Authority and other parties involved. It has been known for a long time (the BfS informed about it, among others, in February and April) and was reported in the Monitoring Group. It has now been decided to construct a new spiral drift section for the blocked area. A corresponding application for the first of two planned construction parts has been submitted to the State Mining Authority.
Update of 30 July 2012
The Asse-GmbH started to construct a bypass to the damaged spiral drift. After the State Mining Authority had swiftly approved the corresponding application in the 29th calendar week, the Asse-GmbH started in the 30th calendar week to mill the new road into the salt. The new road is 4.50 metres wide and 4.50 metres high.
Update of 6 March 2013
The entire so-called spiral drift in the Asse mine can be used again. Following a remediation taking about one year, works could be completed faster than expected. The remediation of the spiral drift serves the safety of the staff and is a prerequisite for a successful retrieval of the waste from the Asse mine.
Update of 19 March 2014
After the old section of the spiral drift has been replaced by two bypasses, the no longer needed old sections could be stabilised with special concrete. These works were completed in March 2014.