Drilling through a mountain in the Italian Alps
In June 2025, Brownline contributed to a very challenging horizontal directional drilling project. In the north of Italy, a gas pipeline was installed by drilling right through a mountain. Many of the challenges with this installation required extreme accuracy in the pilot phase.
The aim of this HDD project was to install a gas pipeline through the mountain where the pipeline aligns parallel to a tunnel that is more than 900 m / 2900 ft long. This new pipeline section will be part of an existing natural gas transportation network. It will serve as a bypass for an existing route that goes around the mountain. The newly installed section will make gas transportation safer and more reliable in the future.
Challenging design parallel to tunnel
Trenchless contractor DIM Group carried out the horizontal directional drilling for this mountain crossing. A design was made for a 951 m / 3120 ft bore next to the tunnel. The drill path kept a consistent pitch of 1.2° and made a large horizontal curve of 53° to follow the curve of the tunnel.
To guarantee this accuracy during the pilot, Brownline surveyed the job using the Drillguide Gyro Steering Tool. In the hard rock conditions, the real-time gyro measurements and Brownline’s steering service kept the drill bit on the right track.
Precise exit required
Preparing a steel pipeline for pullback in a mountainous area with limited space can be very challenging. An accurate punch-out on the far side of the mountain was required to minimize issues during pipe string-out and pullback. Both the exit position and exit direction needed to be exactly as designed.
Where the rough terrain allowed it, we deployed our compact GPS track surface equipment for additional verifications of the drill head’s position. The highly accurate Drillguide Gyro Steering Tool measurements combined with the independent GPS track verification enabled a highly accurate punch-out in the rock, 7 m / 23 ft from the tunnel wall, as planned.
After the successful pilot drilling, the pullback went smoothly and the new gas pipeline was installed safely and efficiently.
