Preparatory work began back in August with the construction of a pre-cut wall for the subsequent breakthrough from the main tunnel towards the equalisation basin. Directly in front of this, PORR Spezialtiefbau is now excavating a pit around 7 metres deep. It is secured by an overlapping bored pile wall with a diameter of 120 cm and anchored with 28 temporary strand anchors and 4 permanent anchors. The bored piles, which are up to 14 metres long, are installed using a rotary drilling rig. A specially manufactured drilling template ensures maximum precision.

Short distances and high quality

Site manager Maximilian Mohn emphasises: ‘The ready-mixed concrete is produced in our own mixing plant – short distances, fewer emissions, maximum efficiency. For quality assurance, we continuously check the fresh concrete and test concrete cubes for compressive strength.’

With the conversion of the historic Forbach hydroelectric power plant into a modern pumped storage power plant, PORR is sending a clear signal for the energy transition. On behalf of EnBW, complex tunnel and cavity structures are being built to efficiently store excess energy from renewable sources and make it available quickly when needed. PORR is responsible for Lot 2 ‘Construction Works’ – including mining for caverns and tunnels, the shell construction of the power plant cavern, two pressure shafts and special civil engineering works. Around 450,000 m³ of rock material will be blasted and excavated from the rock until the planned commissioning in 2027.