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

As Australia’s leading microtunnelling contractor we have experience constructing shafts and installing pipes 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.

Microtunnelling 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.  Microtunnelling 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.

Microtunnelling is used to install pipe 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.

Microtunnelling is a discrete construction method making it an excellent option for congested urban areas. Requiring two vertical shafts, microtunnelling 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.

Microtunnelling 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.

In the microtunnelling 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 microtunnelling 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.

What is the difference between microtunnelling and Horizontal Directional Drilling (HDD) are key methods used for underground construction and utility installation, each chosen based on specific project requirements. Microtunnelling, 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, microtunnelling requires steering correction during installation, with subsequent stages following the initial hole’s path. Microtunnelling removes cuttings and fluid via a slurry pipe, while HDD uses the borehole’s annular void.

Microtunnelling 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, microtunnelling 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. Microtunnelling 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.