Horizontal Directional Drilling of PE Pipe [PE]

Horizontal directional drilling (HDD) has given many municipalities and utilities the opportunity to utilize PE (PE) pipe in a more cost effective and efficient manner than traditional piping materials. A key feature of HDD is that it makes minimal impact on the environment and the community. This results in cost savings due to short design and permitting times and quick installations. Due to its corrosion resistance and fused joints, PE pipe is the product of choice for HDD installation for distribution and low-pressure transmission systems. Its acceptance is increasing as utilities discover they can install PE pipe without concern for “hot” soils, corrosion, backflow, or leakage. In addition, PE pipe’s flexibility gives it a much tighter allowable bending radius than other piping products resulting in HDD capabilities not found with other pipes. This paper discusses the features and benefits of installing PE pipe by HDD for municipal utility applications. To demonstrate the broad effectiveness of this installation method for solving installation problems, this paper discusses various projects including the installation of a new water distribution system and a major water crossing. The publication of ASTM F1962 in 1999 and ASCE MOP 108 in 2005 has helped advance the use of this technology. These publications provide useful design information for HDD installation of PE pipe. They consider both pullback installation and long-term service loads and provide guidance for planning and locating the borepath, estimating forces on the pipe during pullback, and selecting an appropriate pipe DR to withstand the applied loads both during installation and afterwards when soil loads occur. The application of F1962 and MOP 108 to HDD projects is discussed as well as recent research which has enabled some refinement to these design methodologies. Directional drilling initially started out as a highly specialized installation method, primarily for river crossings. Today because of PE pipe’s capabilities, it is advancing toward the commonplace for municipal utilities.