Drilling Through Stone and History: HDD Success at Kielder Castle

On the rugged edge of the Scottish Borders, a complex horizontal directional drilling (HDD) project unfolded beneath the historic grounds of Kielder Castle in Hexham. The task: install district heating pipes and electrical ducts from a wood chip boiler house to the castle—120 meters away—using trenchless technology.

The job, completed by Kevin Hamill and Mole Group Utilities, demanded a high degree of accuracy and control. The drill path had to pass beneath pre-installed flood defenses at a depth of 3 meters, cross under the Kielder Burn watercourse, and ascend a steep 20-meter embankment leading up to the castle grounds. No big deal….

Complex Ground Conditions Demand Expert Execution

The geology presented significant drilling challenges. The subsurface along the bore path was far from forgiving—layers of sandstone, limestone, granite, and cobble created a tough mix that demanded robust equipment and experience.

Despite these conditions, the pilot bore was successfully completed with pinpoint accuracy, hitting the target exactly as planned.

From Pilot to Pullback

After the pilot bore:

• A 10-inch fluted reamer was used to enlarge the borehole.
• A 14-inch reamer followed to pull back the district heating pipes and electrical ducts in a single pass.

Despite the challenging terrain, the pullback went smoothly, with no disruptions to the surrounding environment or historical site—a key benefit of using HDD over traditional excavation methods.

A Real-World Test for Advanced HDD Guidance Technology

To successfully navigate this route, Mole Group Utilities relied on the DCI Falcon F5+ locating system with integrated GPS. Known for its extended range and precision in challenging environments, the Falcon F5+ played a critical role in keeping the drill head on target from start to finish.

The system’s GPS module enabled accurate bore path tracking even as the team contended with shifting geology and elevation changes. Paired with an Aztec drilling rig, this combination gave operators the confidence to steer precisely through unpredictable subsurface conditions.

Powering Success with the Right Tools

While the success of this installation ultimately reflects Mole Group Utilities’ expertise and execution, it also demonstrates the impact of using advanced HDD tracking systems like the DCI Falcon F5+. In tough terrain where accuracy is non-negotiable, having the right technology in the ground makes all the difference.