The project team successfully executed a 230 m HDD directional drill under the A7 motorway, navigating challenging geological conditions consisting of limestone, marl, and claystone. Three HDPE product pipes (2 x 315 mm, 1 x 280 mm, SDR 11) were installed at a True Vertical Depth (TVD) of 14.5 m.
Technical Specifications
- Drill Length: 230 m
- Rig: MT 60
- High-Pressure Mud Pump: 1,300 l/min
- Pilot Hole: Double Rod System, 7 ½” TCI Roller Cone Bit
- Guidance / Locating System: Falcon F5 / Underground Magnetics
Crossing Obstacle: A7 Motorway
Bore Profile:
- Entry Angle: 12°
- Exit Angle: 12°
- Vertical Bend Radius: 350 m
- True Vertical Depth (TVD): 14.5 m
Geological Conditions & Pipe Specifications:
- Geology: Limestone, marl, claystone
- Product Conduits: 2 x HDPE 315 mm, SDR 11; 1 x HDPE 280 mm, SDR 11
- Drilling Fluid: Bentonite-based
Final Pullback Force:
- 315 mm – 120 kN
- 315 mm – 109 kN
- 280 mm – 60 kN
