Directional boring is a process used to drill holes below the surface of the earth. Rather than drill these holes straight down, directional boring allows workers to create horizontal bores that run parallel to the ground above. This process is used to place many types of underground utilities, including electric and telephone lines, as well as sewer, water, and gas piping. Directional boring may also be known as horizontal directional drilling (HDD) in some regions.
This process is performed using heavy-duty directional boring machines, which often rely on hydraulics to generate sufficient drilling power. Prior to drilling, workers first perform geological surveys and soil testing to ensure boring can be completed safely and effectively. They then create a starting and ending pit, which represents the start and end of the piping run.
Next, the directional boring machine drills a small pilot hole using a special metal bit. This pilot hole serves as a guide for the remaining bores. After the pilot hole has been drilled successfully, workers drive a metal cutting tool, or reamer, through the soil. The reamer cuts out a path slightly larger than the diameter of the planned piping or conduit. Finally, the reamer is run through the bore once more, and is used to drag the pipe or conduit into place.
Directional boring often requires the use of a special drilling fluid, which is made from water, mud, and chemicals. This fluid travels through the soil with the drill and reamer to keep the bore clean and to help remove mud, rock and other materials. Drilling fluid also cools the cutting tools to remove some of the heat generated by the boring process. This helps these tools stay strong and sharp, and helps to prevent breakages and failures.
One of the major advantages to directional boring is that it allows workers to drill holes without disturbing the land above. This means that pipe or conduit can be laid beneath a river, a busy road, or a crowded urban area. It allows pipes to be installed quickly and at a low cost compared to traditional trenching methods. It also helps to protect the ecosystem above from disturbance, which is of critical importance in sensitive environmental areas.
Directional boring also provides some challenges and limitations to workers in some types of applications. This process can only be used when subsoil layers consist primarily of rock or hard soil. It cannot be used in loose, sandy soil or gravel. This technique may also not be appropriate for applications where the pipe must be installed very deep below the ground.