Development of trenchless line installation and repair began in the 1960’s. Since its invention, it has become one of the most popular methods of installing and repairing underground lines, especially in urban settings.
Which Utilities Use Trenchless Installation?
Understanding how trenchless technology benefits a city or neighborhood begins with knowing which utilities use this method for installation and repair. In some manner, almost all services can use this technology.
Trenchless for Water Lines
Water lines are those lines which bring potable water to homes and businesses that is used for bathing, cooking and drinking. Waterlines can be installed by using methods like HDD and can be serviced through a myriad of trenchless methods like pipe penetrating radar.
Trenchless for Sewer Lines
Sewer lines are lines that retrieve and redistribute wastewater from homes, businesses and public areas through sanitary sewers, which move water from showers, toilets and sinks; and storm sewers which move excess rain water from city streets. Sanitary lines require the maintenance of gas venting and gas detectors.
Trenchless for Gas Lines
Gas lines bring natural gas to homes in order to power gas stoves, a home's heating system and gas fireplaces. Contractors can use trenchless tech in order to detect gas leaks and maintain the integrity of the main line without drastic trenching.
Trenchless for Electric Lines
Electricity utility lines run cables to homes and businesses to power lights, electric appliances and entertainment devices. Electricity lines, if not run above ground, can be installed below ground within piping systems set in place by pipe ramming, HDD or other trenchless boring methods. These lines are usually set in place with the use of ground penetrating radar (GPR) to avoid cross boring.
Trenchless for Telecommunication Lines
Telecommunication lines are those which run cables to homes to provide phone service, cable service and internet service. Like underground electricity lines, telecom lines are installed with the help of GPR as well.
All of these utility lines can use trenchless installation methods and maintenance methods in a cost-effective and less disruptive manner.
How Are Lines Serviced or Installed?
There are many different trenchless methods usable by utility workers. Which particular methodology employed depends greatly on the type of line maintained and environmental conditions. These methods include cured-in-place pipe, pipe ramming, auger boring and more.
Cured-in-place pipe, better known as CIPP, is a fiberglass lining permeated with resin. It is most commonly used to repair water, sewer, and gas lines. Most often, workers use this method to repair breaks and cracks in the pipe, offset joints or even poor initial construction.
CIPP creates a pipe within a pipe, meaning there is no need to remove or replace the original line. While it does reduce the interior circumference by about a quarter of an inch, it does not result in flow reduction.
Workers use CIPP on pipes ranging from three-inches to 96-inches in diameter. Most only use it on the small section in need of repair. However, CIPP can run as far as 1500 feet.
Pipe ramming is another trenchless method. As the name implies, a tool rams the casing into the ground. The device, which attaches to the end of the pipe, uses percussive blows powered by compressed air to insert the new tubing in place. Once laid, compressed air blows through, clearing the line of debris.
This method allows the laying of new pipe, particularly under roadways, but can also install vertical pipes as well. It is not used to replace existing pipe; there are other methods like this to perform replacement projects.
Pipe ramming has a distance of up to 98-feet or 30-meters. Typically, tubes used in pipe ramming are as small as 4-inches and as large as 60-inches. A variety of utilities can use the lines run via this method.
Like pipe ramming, auger boring digs a trench to place pipe without disrupting the surface. Instead of using percussive blows to insert the pipe into the ground, auger boring uses an auger to drill the hole for the line. In most cases, the casing is inserted into the hole as it is boring. Removal of soil in the line occurs as the auger bit comes back out of the line.
All utilities benefit from boring auger use. Smaller bores, those under 6-inches, work for electric and telecom fiber optic cables. Water, sewer and gas lines use large bores. Augers bore up to 500-feet with a diameter of up to 60-inches.
The trenchless technique of moling is a combination of boring and pipe ramming. With moling, a pneumatic tool drills the path for the line to run. Unlike with pipe ramming, the tool, better known as a mole, creates the path before pipe insertion, much like boring does for its line. However, workers insert the line after the mole completes its task.
Construction workers use moling for smaller water lines, electric and fiber optic cables, or for heating coils. The mole is only about 6-centimeters in diameter and is approximately 60-cm long. Unlike other trenchless tools, the insertion point is only a couple meters in diameter. Other devices require a larger starting area.
In some cases, workers use water jetting to create holes for lines. Water jetting is the use of high-pressure water, and sometimes an abrasive substance cuts a hole in the ground. Like a mole or auger, the water creates the hole before a line runs through it.
However, there is little control over how large the hole is, making it an unpopular choice in comparison to other trenchless options. In most cases, water jetting is used mainly to help clean lines already in place. If necessary, once cleared of debris and soil, other methods, such as CIPP, can repair problems.
Microtunneling is, as the name implies, the boring of small tunnels used to lay gravity pipes, such as water and sewer lines. The tool for this job is operated remotely, as the tunneling diameter ranges from two-feet to five-feet.
Often, workers use microtunneling in conjunction with pipe ramming. The tunneling tool creates a path for the pipe to go, and the line is rammed in after using the ramming tool. The drive length of the microtunneling tool is dependent on the machine itself. Some have a limited range of 100-meters while others have a range of as much as 1000-meters.
The Benefits of Trenchless installation
There are many advantages for using any one of these trenchless techniques in an urban setting. The greatest draw in using these methods is the reduced cost when compared to traditional trench work. It also takes less time to complete a project, making it possible to rehab or run more new line each year.
Many of these techniques help protect the surrounding environment. Using moling or microtunneling offers less disruption to the soil above and fewer settling issues once the lines are in place. The use of CIPP allows workers to run seamless plumbing from the connection point to the end.
The use of trenchless technology in an urban setting is gaining in popularity. The project determines the exact method. However, with so many different ways to lay and repair all types of utility lines, there is a trenchless option to meet the need.