The central shaft will be used as the reception shaft for the west section TBM and as the launching shaft for the TBM boring the east section up to the existing shaft “Schacht 1 Oeynhausen”. After TBM reception, this 100 m deep shaft will be strengthened. The drainage tunnel will drain the mine through the segment lining into an invert precast channel, which transports the drained water towards the west, out of the mine into the sewage treatment plant Gravenhorst. The two drives will be bored partly with pea gravel sections, where mine water drainage is required, and partly with 2K-grout sections as segment lining backfill, where mine water drainage is not required.
A particular challenge arose due to the location of the construction site in an inner-city park, which meant that only a tightly dimensioned installation area was available. Considerable restrictions also had to be taken into account in the delivery of the jacking pipes with an outside diameter of 4,500 mm and an individual weight of approx. 32 tons.