Trenchless technologies are the methodologies used to install or replace existing underground infrastructure such as pipelines, conduits, electrical lines with minimum impact on surface areas and surroundings.
Open-cut methods are also known as “trenching” or “shallow digging,” where the underground infrastructure is exposed for excavation or construction purposes.
Why are trenchless technologies desired over open-cut methods?
Trenchless technologies offer many advantages compared to open-cut methods, including minimal impact on surface areas and surroundings, no ground disturbance along the length of the work zone (noise, vibration, dust), reduced traffic congestion, reduced project duration, and lower cost to excavate by reducing impacts on traffic during the construction phase.
What are examples of trenchless technologies?
Trenchless technology includes a variety of installation and replacement techniques that either minimize excavation (open-cut) or do not require any (closed-cut). They include:
- Horizontal directional drilling
- Indirect pipe bursting
- Pipe jacking
What are some of the benefits of trenchless technologies over open-cut methods?
Trenchless technology is generally more cost-effective than traditional excavation techniques because it requires less time to complete the work zone.
This results in reduced traffic congestion during construction, lower costs due to the minimization of material handling, and less workforce requirement with no ground disturbance along the length of the work zone.
What are some disadvantages associated with trenchless technologies?
Although most trenchless technology is less disruptive than traditional excavation techniques, there can be considerable capital outlay for certain projects (directional drilling) and certain geographical areas like limited ground conditions.
- Horizontal Directional Drilling
Directional drilling works by advancing a borehole through the ground with a bentonite slurry, using steerable motors and guide equipment.
It requires the use of an hdd drilling machine to install new pipelines or existing underground infrastructure such as water supply lines, electrical conduits, fibre optic cables, natural gas pipelines, and others. The directional drill is most widely used for the installation of large-diameter pipelines where open access is available and ground conditions are appropriate.
Microtunneling uses a small hydraulic excavator (or “vacuum” excavator) equipped with a TBM to dig, place, and compact soil/rock while simultaneously installing the pipe string. This method is usually used in conjunction with open-cut methods, where a microtunneling machine builds an underground pipeline or other underground structure beneath the surface.
- Indirect Pipe Bursting
It is best suited for trenchless rehabilitation of existing pipelines in areas with limited access or restricted right-of-way. The new pipe is pulled through the old pipe using a combination of hydraulic jacks and thrust trays without opening a trench. This method is typically used for the installation of water supply lines, natural gas pipelines, and others.
- Pipe Jacking
Pipe jacking involves the controlled advancement of a small shield through an existing pipeline, using the pressure head of water or low viscosity oil behind it to push against soil or rock ahead. This method is usually used in areas with good ground conditions, where edging can be easily introduced to ensure a smooth soil/rock profile.
What are some considerations for using trenchless technologies versus open-cut methods?
Trenchless methods require less time to install than traditional open-cut methods, which can be particularly advantageous in congested metropolitan areas where road closures, traffic restrictions, and detours are difficult to manage.
Trenchless construction also results in considerably lower service outages (and thus reduced impact on customers) and has a much smaller footprint than traditional cut-and-cover methods of installation.
What are some key considerations to take into account when deciding which trenchless technology will work best for a particular project?
Trenchless technologies offer a range of advantages over open-cut excavation, including less time and money required on the job site, but each has its own unique set of benefits and limitations.
The method selected for any given project will depend on the local ground conditions (ranging from stiff clay to lose sand or gravel), presence of groundwater inflows along the pipe path, existing utility infrastructure in the excavation area, desired installation speed, and access restrictions.
Why use trenchless technologies instead of traditional open-cut methods?
Trenchless technologies have become more popular but are still considered to be a niche market by many contractors and industry associations. This is primarily because of the cost involved with acquiring specialized equipment or hiring contractors who specialize in this area. However, trenchless techniques can often deliver the same results as traditional excavation methods but with less disruption to the work area and greater safety.
Project goals should be identified to determine which methods will bring about the desired results while minimizing costs, environmental impact and community disruption.
Trenchless alternatives can help reduce noise pollution by replacing large equipment like backhoes with, say, hdd drilling machine, that are traditionally used for excavation.
There is much less traffic disruption with trenchless alternatives than with open-cut methods since the work area remains in place. Also, when trenches must be opened to install the new line, they are often backfilled immediately after construction.
Due to limited water damage during projects, trenchless methods can reduce the risk of water main breaks and increase the quality of construction.
Trenchless alternatives can speed up projects by minimizing excavation work and reducing the need for specialized equipment. Projects are also completed more quickly, which reduces project time, construction costs, community disruption and environmental impact of heavy machinery.
Trenchless alternatives are the future of construction. As cities and countries transition towards more sustainable, efficient and cost-effective methods, we predict that trenchless technologies will become increasingly popular and widely used.
These technologies require less time to install and significantly less excavation equipment and labour than traditional open-cut methods. The speed and low cost of trenchless technology are particularly advantageous in congested metropolitan areas where road closures, traffic restrictions, and detours can be difficult to manage.