Utility installation through congested right-of-ways (ROWs) or inaccessible terrain can be difficult using traditional construction methods. Under these conditions, installation by horizontal directional drilling (HDD) warrants serious consideration. HDD allows for pipeline installation at a greater depth than typical methods, which can help avoid conflicts with existing utilities. Construction impacts can be minimized with HDD by avoiding the need for trenching along the entire pipeline alignment. By avoiding trenching, HDD can allow for installation through sensitive land use areas (i.e. wetlands, preserves, bodies of water), reduce the need for maintenance of traffic (MOT) when crossing major roadways, and reduce land restoration costs. Additionally, the use of seamless high-density polyethylene (HDPE) pipe for HDD installations can increase pipeline integrity relative to jointed pipe (i.e. PVC or DIP) and reduce future maintenance needs.
Designing safe, efficient, and effective HDD installations is more complex than typical open-cut construction. Factors that must be considered for HDD designs include the purpose of the pipeline, geotechnical conditions, alignment geometry, installation constraints, and pipe strength rating. The pipe strength rating is a particularly important consideration due to the potential for generating significant tensile forces during the pullback installation procedure. In addition, properly selected pipe material can reduce the risk of collapse due to the effects of long-term deflection (creep). Proper consideration of these factors results in an HDD design that is a safe, robust, and cost effective.
Over the years, Johnson Engineering has designed HDD pipelines that range from four to 42-inches in diameter and cross major roads (including I-75) and large bodies of water (including the Imperial River and Boca Grande Pass). We approach HDD projects with a broad perspective that takes into account current material design parameters and construction methods as well as the current and future needs of our clients. In addition, our close relationship with local HDD contractors provides us with unique insights into the advantages and limitations of HDD construction. Prior experience is a key asset that should be considered for HDD projects, and Johnson Engineering has the experience and expertise to ensure that these projects are successful.
For more details contact Mike Dickey, P.E. at [email protected].