Horizontal directional drilling (HDD) is a steerable trenchless method of installing underground pipes, conduits and cables in a shallow arc along a prescribed bore path by using a surface launched drilling rig, with minimal impact on the surrounding area. Horizontal directional drilling is the most commonly used trenchless process for installing water pipe and is suitable for a variety of soil conditions and jobs including installation of pipe crossing waterways, roadways, congested areas, environmentally sensitive areas, and areas where other methods are costlier. Unlike other techniques, horizontal directional drilling provides less traffic disruption, lower cost, deeper and/or longer installation, no access pit, shorter completion times, directional capabilities, and environmental safety.
Horizontal directional drilling requires a specialized boring machine to create a horizontal shaft and subsequently pulls the new pipe into and through the opening with the aid of drilling fluid. Horizontal directional drilling involves three essential steps. First a pilot bore is created, covering the distance over which the pipe is to be installed. Highly sophisticated electronics enable the drilling rods to be carefully guided and its direction of travel to be monitored. Reamers are then pulled back to obtain a diameter large enough to accommodate the diameter of the pipe. Simultaneously, drilling mud is pumped into the bore to stabilize the boring and to prevent soil collapse. In the final step of horizontal directional drilling, the new pipe to be installed is pulled back through the bore. Horizontal directional drilling provides the option of completely replacing old pipelines in a new location as an option to rehabilitating an existing pipe.
CertainTeed Certa-Lok PVC Pipe
is a non-metallic, easy-to-assemble restrained joint PVC piping system ideal for horizontal directional drilling. While ease of installation usually influences the type of pipe for trenchless construction projects, material costs are additional factors. Although both HDPE and PVC pipes greatly reduce post-installation maintenance expenses compared to traditional materials, their dissimilar material strengths can frequently result in economic and performance differences. Because PVC is inherently stronger, the wall thickness required for pressure applications is substantially less than that for HDPE pipe thus making PVC a perfect choice for horizontal directional drilling applications.