Thinking Outside a Very Small Box: HDD Success in Queensland, Australia

When it comes to horizontal directional drilling (HDD), every jobsite presents unique challenges. When boring to install HV power for the new Toowoomba Hospital being built, Harley Cox, Troy Gardner, and Scott Waters faced a particularly tricky situation. However, with strategic planning, precise execution, and the right equipment, they successfully tackled the job.

The Challenge: Short Distances, Extreme Pitches, and Tight Access

This project involved three bores, each only 40 meters in length, through reactive red clay. And in just those 40m, the exit pitch needed to match the existing batter steepness—at 60%.

All this while navigating a web of obstacles:

• Double-layered Rio mesh reinforced the batters, and
• 17-meter-long nails drilled into the walls secured the mesh with 85MPa grout —all sources of potential interference to the locating system.
• Structural piers every 8 meters, 1 meter in diameter, extending 60 meters deep into the earth.
• A 700mm clearance between nails, through which they needed to pull a 500mm reamer.
• Other trades operating in the already congested space

Clearly, this job wasn’t easy, and precision was key.

The Solution: Digging Smart, Drilling Smarter

To navigate these demanding conditions, the team began by managing their bore profile using a TeraTrak R1. Walking the jobsite provided them with a precise understanding of terrain variations and slopes, enabling them to develop an accurate and efficient bore plan.

The TeraTrak also helped them determined their initial setback distance and angle. With such a steep exit pitch, placing the drill at a reasonable depth was critical, so the team created an 8m-long ramp leading into an 8x4x1.7m deep pit for the drill to sit in, reducing the effective pitch at entry.

• First bore: 1.2m deep at 0% pitch.
• Second bore: 1.5m deep at -10% pitch.
• (Third bore is still to be completed at this time.)

From there, they relied on top-tier HDD technology to get the job done. A JT3020AT dirt setup with a Melfred Borzall Red Diamond Paddle was used to complete the drilling. For locating, they used an F5+ DigiTrak with an FT5p sonde for accurate bore tracking. Using the DigiTrak system allowed them to bypass the many sources of interference and locate clearly and without interruption, leading to a faster and more accurate job. The team also logged their bore with LWD Cloud, enjoying how they could share the data in real-time.

Results: Precision Execution in a Tough Environment

Despite the demanding site conditions, the team successfully pulled multiple conduits for the new Toowoomba Hospital’s HV power supply. Through strategic drilling and smart site modifications, they overcame the challenges of limited space, steep angles, and structural obstructions.