Superior Microtunneling Solutions by North America’s Expert Microtunneling Contractor

When precision is required – our unique microtunneling technology delivers results.

Bothar provides superior microtunneling solutions using Bothar Built Fully Steerable Device (FSD) microtunneling machines as well as equipment manufactured by world-leader Herrenknecht to complete trenchless installation of pipelines. Our solution uses a remotely-controlled, guided operation that provides continuous support to the excavation face by applying mechanical or fluid pressure to balance groundwater and earth pressures. This slurry-supported excavation process and comprehensive range of AVN systems with specialized cutting heads make it possible to tunnel in all types of ground conditions ranging from silt to clay to incohesive soils, and further to gravel and hard rock. Just one of the reasons we are considered North America’s leading microtunneling contractors.

What is microtunneling: the microtunneling method explained

Microtunneling is the leading method of underground construction used to install new pipelines with minimal surface obstruction and environmental impact. This trenchless construction method requires a small vertical shaft to tunnel under roads, rivers and railways, densely populated urban areas, etc.  Microtunneling highly reduces ground disturbances and avoids interference with above ground activities including traffic, people, marine life and other surface environments. This process  is slurry supported,  which enables this method to be used in almost all ground conditions from soft, sandy soils to gravel and rock. 

Microtunneling is used to install pipelines ranging from 600 mm to 4,000 mm over short or extended distances. It is primarily used for utility pipeline installation, water and wastewater system installation, lake and marine intakes and outfalls, and can also be used to install pipelines for proper storm runoff, flood mitigation and redundant power systems to ensure coverage.

A process that minimizes public and environmental disruption

Microtunneling is a discrete construction method making it an excellent option for congested urban areas. Requiring two vertical shafts, microtunneling contractors are able to complete complex projects without needing to close roads, block access to buildings, disrupt public green spaces or other environmentally sensitive areas.

Microtunneling is a low pressure drilling method and our team monitors ground settlement during the entire tunnel process to ensure the integrity of the surrounding infrastructure and safety of the work site. This approach also reduces frack out risk and leads to clean, non-toxic drilling muds making it a safe method for environmentally sensitive areas.

Microtunneling advantages

  • Cost effective drilling method

  • Slurry-supported and adaptive process

  • Significantly reduced environmental impact compared to traditional methods

Bothar: Microtunneling contractor with end-to-end expertise like no other

At Bothar, we excel in every facet of trenchless technology, delivering comprehensive microtunneling solutions that encompass construction engineering, equipment procurement, and project management.

As North America’s leading microtunneling contractor we have experience constructing shafts and installing pipe in a variety of geological conditions and weather extremes. With our experienced team and in-house solutions including shaft construction, direct pipe installation, pipe jacking and auger boring, we are able to complete trenchless crossing projects effectively and efficiently.

Understanding microtunneling benefits

Microtunnelling is gaining in popularity over dated, traditional pipe installation technologies that use open-cut methods because of the construction, environmental and social benefits that lead to reduced project cost.

Construction benefit

Microtunnelling can be performed with minimal disturbance to the surface especially when compared to older technologies that require a pipe long open trench. This process requires an entry and an exit point to be excavated which takes a fraction of time with a significant reduction to the environmental impact. Microtunnelling methods provide continuous support to the excavation face by applying mechanical or fluid pressure to balance groundwater and earth pressures. Altogether, these construction benefits reduce the time to complete tunneling projects and provide overall cost savings.

Environmental benefits

The microtunneling process leaves a smaller footprint than open-trench tunneling methods making environmental remediation and site rehabilitation faster. In addition to reduced time, the rebuilding of pavement, sidewalks and landscaping is also avoided further reducing the total project cost.

Social benefits

One of the main benefits of microtunneling is that it can be performed in high-density urban areas without interfering with local businesses, pedestrians and traffic. Microtunneling sites are discrete and enable normal life patterns to continue. These community costs are not included in overall project estimates but are important considerations when embarking on tunneling projects and gaining support from the public.

Microtunneling and HDD

What is the difference between microtunneling and Horizontal Directional Drilling (HDD) are key methods used for underground construction and utility installation, each chosen based on specific project requirements. Microtunneling, accommodating a larger diameter of up to 3.5 metres, often suits more substantial projects compared to HDD’s typical 24-48 inch range.

While HDD needs constant human control, microtunneling requires steering correction during installation, with subsequent stages following the initial hole’s path. Microtunneling removes cuttings and fluid via a slurry pipe, while HDD uses the borehole’s annular void.

Microtunneling offers better precision, maintaining an accurate grade with a typical 50mm tolerance around the design profile, whereas HDD has a 2-meter radial tolerance, with 2-5% depth accuracy.

For troubleshooting, personnel can enter the microtunnel pipe depending on its size, unlike in HDD, which necessitates bringing tools to the surface for repair or replacement. Also, microtunneling technical equipment is remote-controlled and goes underground, while HDD equipment remains on the surface.

Although these methods are not typically compared to each other due to their distinct applications, it’s worth noting their different use-cases. Microtunneling is generally preferred for civil projects requiring accurate grade and often used with short concrete pipes from a shaft at grade. On the other hand, HDD, which does not offer the same grade, is conducted from the surface and typically involves pulling back steel or plastic from the exit side to the entry.

Microtunneling and pipe jacking

In the microtunneling process, small-diameter pipes (under 4,000 mm) are laid underground in a single operation. During pipe jacking, the tunnel boring machine is forced through the soil by hydraulic cylinders to clear a path for the pipe. The process is remotely controlled, as microtunneling is only used for laying pipes that are not normally entered by humans. In most cases, a concrete thrust wall is erected in the shaft, which the main jack bumps against as it pushes the pipe through the ground. Pipe jacking can also be used in larger pipe tunnel projects when ground conditions are difficult and mechanical or manual excavation is not possible.

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