An Unboring Yet Basic Guide to Boring

By Will Carpenter
Published: June 18, 2018 | Last updated: July 5, 2023
Key Takeaways

Directional boring may solve pipeline installation issues, as long as you play by the rules of common sense and do your homework.

Directional boring isn't boringif it's done correctly and can be downright terrifying if it isn't. Directional boring isa trenchlessway to put drains and pipes into the ground that uses a directional bore between two access pits (one at the beginning and one at the end, or terminus) through which a pipe is inserted and connected. Unlike conventional pipe installation that uses trenching, it avoids obstacles, doesn't destroy streets, lawns, or flower beds and may work for your project.


Most plumbing and mechanical contractingfirms will know whether you can accomplish your project with directional boring and will likely give you a cost estimate or you may decide to tackle the job yourself.

A Boring Subject, Basically

Directional boring starts with an access pit near one end – usually near the home or other outfall of the pipeline. Then, a pilot bore is created between this pit and a similar pit dug or bored at the other end. This pilot bore is a small-diameter hole that shows that the ground can bear a trenchless pipe placement and it acts as a guide for the larger hole required to house the pipeline. A larger boring head is placed into the pilot hole. It bores along the same path created by the pilot bore, making the original horizontal hole large enough to accommodate the pipeline. The pipe to be installed is attached to the boring bit that just enlarged the hole and pulled back through the bore and the job is finished without digging up your yard or the street through your neighborhood.


When Directional Boring is the Right Choice

Directional boring can be the preferred method for pipe installation when there are obstacles you want to avoid, like buildings (large or small), underground utilities, your front or backyard, your flower beds, children's play areas or any other location where a large, open trench poses serious inconvenience orhazardto life and limb.

Large tunnels, such as those that pass beneath rivers and through mountains, i.e. the Eisenhower Tunnel in Colorado, or railroad tunnels and mining operations worldwide, are the result of directional boring on an industrial scale. These directional boring projects use large, self-propelled machinery with specialized boring heads called tunnel boring machines (TBMs) and may be referred to as moles or moling machinery, after the common mole, subterranean mammals with small hind legs and oversized forelegs adapted to digging the tunnels in which they live.

Pro or Putterer?

Ideally, directional boring is performed by trained technicians. However, the proliferationof small, horizontal boring machines (learn more with a Guided Boring Machine Maintenance Checklist) in nationwide chains of do-it-yourself stores has placed small scale directional boring within the reach of ambitious homeowners. Whether created by trained professional or savvy amateur, a well-done bore takes practice and control. Small errors indirection or depth can amplify the difficultyof pipe installation.

Anyone—pro or enthusiastic putterer—who attempts a bore must have the ability to read a plot and determine a well thoughtout path for the new bore, including its depth below groundlevel…Pros know—and amateurs should take note—that free-flowing pipes require a smooth bore. Do-it-yourselfers should closely follow the instructions for their machine.

Minor errorsin direction or depth can lead to larger problems. (Learn more in Signs Your Borehole is Losing Integrity.) Not only must you know the path your bore will follow, you must know what other utilities are present near your design pathway. You also have a responsibility to check with your state or province utility location service. In each state in the US, One Call can identify underground cable, electric, gas, water, sewer and combustible pipelines and conduits on your job site.


Simplydial 811 from a landline or *811from a cell phone.

Your state's call center will answer and provide you with all the information you need to avoid difficulties. In Canada, the number for the One Call system is 1-800-474-6886.Failure to use these free services can be costly. 

The Round-Up

Directional boring deliversflexibility while avoiding common obstacles. Whetheryou plan to plot a design path that crosses through a labyrinth of underground utilities or simply avoid destroying the bed of Peruvian Lilies that took so long to get "just so," directional boring may be your answer. Whether you plan to contract the job to an expert or do it yourself, check with a pro to see if directional boring is the best solution.

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Written by Will Carpenter

Will Carpenter

A retired merchant seafarer, Will Carpenter sailed the world extensively before settling as far from the sea as possible. Now a technical writer, Will lives in the "hills and hollers" of Tennessee with two formerly feral cats.

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