Editorial: 10.13.2020

Directional Boring: A Solution for Safer, Non-Invasive Utility Installation

— Kurt Dulle, Project Director

Directional boring machinery being operated by a construction worker

Picture this: You manage construction and facilities for a sprawling campus. Plans have been made for a new building project that will make a difference in attracting new students, employees or clients. The new facility is an enormous undertaking, considering the campus has been built over the course of 50 years or more. The campus attracts hundreds, if not thousands of occupants daily. The new, signature building project is in the middle of it all, alongside decades-old infrastructure, roads, pedestrian routes and more. Before the new building can be erected, infrastructure must first be updated. There is a web of complexity underground, and documentation gets less reliable the further back in time it reaches.

How do you get it done without interrupting service to all your existing buildings and operations? Where do you start? How do you protect pedestrians and traffic? And how do you minimize the headaches?

Part of the solution for the utility component could involve directional boring, an installation alternative to creating large, open excavations that can help solve some of these logistical challenges.

What is Directional Boring?

Directional boring (aka horizontal directional drilling) is a minimal impact, trenchless excavation method. This process uses a directional drilling rig on the surface to install utilities along a path underground without digging open trenches for the entire utility length.

  • Starting with small potholes, an experienced directional boring crew exposes known utilities along the path to determine exact utility depths.
  • A small pit is excavated at the start and end points. Then, a rotating drill rod with a bit attachment is used to create a small diameter pilot hole along the path from the start point to the end point.
  • Next, the pilot hole is enlarged as the drill pipe bores back and forth along the alignment using a larger drill bit attachment until enough space is created to allow installation of the utility. Dirt and debris are extracted along the way.
  • Finally, the utility is pulled through the enlarged bore hole for the length of the pathway. Crews patch up the small pits and the area above the entire alignment is unaffected.

Directional Boring Step by Step Explainer

Directional drilling is commonly used where cut-and-cover utility installation is not ideal, typically where the pathway encounters obstacles. Examples include roads, railroads, wetlands, water bodies or areas with dense utilities. It is also helpful in areas with high-volume pedestrian or vehicular traffic. In these sensitive areas, directional boring offers many benefits including to:

  • Mitigate traffic disruption
  • Enhance safety
  • Reduce existing utility disruption
  • Provide deeper or longer installation
  • Reduce installation time
  • Increase directional capabilities
  • Potentially reduce construction and restoration cost

The Added Value of Subsurface Mapping

The key to successful execution of utility projects is collaborating early and planning detailed task sequences. Understanding campus operations, how to efficiently put work in place and maintaining public safety are major objectives for the project team. That is why detailed knowledge is paramount prior to planning an infrastructure upgrade. Combining subsurface utility mapping with directional drilling creates a valuable set of resources to enhance safety and minimize demolition for your project.

Castle performs initial subsurface utility mapping to get an accurate picture of the exact position and location of existing utilities, live or abandoned. This helps to provide data to inform design, plan the work and increase safety by minimizing the potential for dangerous utility impacts that could stop service. The mapping deliverable also provides owners with accurate documentation they can use for facility management and future planning. In fact, mapping deliverables are a tool that can be updated for the life of the facility.


Determining the most effective excavation method for an infrastructure upgrade is crucial to set your project up for success. Directional boring offers an innovative solution for safer, non-invasive utility installation, especially on a busy site with potential surface obstacles. With early and accurate information gathering, an experienced construction team can determine if directional boring would be right for your site.

About the Author

Castle Project Director Kurt Dulle is responsible for leading the firm’s MEPFP & Utility group. He oversees a team specializing in managing and estimating projects for mechanical, electrical, plumbing, fire protection and utility clients. Balancing quick turnaround, smaller-volume projects with large projects, plus emergency response services, is a daily responsibility. During his career, Dulle has served as a laborer, estimator, project manager and project director, providing him with a deep understanding of hands-on site work while building exceptional knowledge to develop accurate costs and schedules.


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