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HORIZONTAL DIRECT DRILLING
Horizontal Directional Drilling (HDD) is a sophisticated, trenchless method used to install underground utilities—such as pipelines, conduits, and cables—along a precise, pre-determined path.
Unlike traditional open-cut excavation, HDD allows us to install infrastructure beneath obstacles like rivers, roads, railways, and protected areas without disturbing the surface. This technique minimizes environmental impact and disruption, making it the preferred choice for complex and sensitive projects.
1. Pilot Hole Drilling
A small-diameter pilot hole is drilled from an entry point on the surface, following a gentle arc that bypasses the obstacle and exits at the target location. The specialized drill head is steerable and is constantly monitored by advanced guidance technology to ensure millimeter-level precision. A slurry of drilling fluid (mud) is pumped down to lubricate the drill, stabilize the bore, and carry soil cuttings back to the entry pit.
2. Pre-Reaming (Borehole Enlargement)
Once the pilot hole reaches the exit point, the drill head is replaced with a larger cutting tool called a reamer. The reamer is pulled back through the bore path, rotating as it goes, to gradually widen the hole to the necessary diameter to accommodate the final product pipe. This process may be repeated several times, depending on the required size of the final utility.
3. PIPE Pullback
In the final stage, the pre-welded utility pipeline or conduit is attached to the reamer via a swivel (which prevents the pipe from twisting). The drilling rig then pulls the reamer and the attached pipeline back through the enlarged borehole, installing the utility safely underground.
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