FAQ's

We’ve answered the most common ones.

General Questions

Trenchless technology refers to construction methods used to install new pipelines or rehabilitate existing underground services with minimal surface disruption. Traditionally pipelines have been built above the surface or laid in a slotted excavation (trench). Due to surface and now subsurface congestion, these construction methods are becoming increasingly more costly and challenging to undertake. Subsequently, trenchless pipe installation methods have been developed to install pipe from one location to another minimising the surface activities.

Due to the complex nature of pipe installation methods and operations, engineering models have been developed to estimate and minimise project and asset risks. Trenchless Engineering Australia offers a range of engineering products and services to streamline the design and construction of pipeline and conduit assets. Examples include assessment of frictional, bending and pressure loads on pipe during installation to minimise risk of product pipe damage, assessment of bending stresses, support reaction loads and pipe spans for temporary breakover design or geotechnical analysis of arching stresses and settlement modelling. Refer to the Products page for more information on how project risk can be assessed for projects.

  • Horizontal
  • Directional Drilling (HDD)
  • Pipe Bursting
  • Microtunneling
  • Auger Boring
  • Cured-in-Place Pipe (CIPP)
  • Sliplining
When surface disruption must be minimised, such as in urban areas, under roads, rivers, or environmentally sensitive zones.

Drilling fluid is a mix of water with thickening additives such as bentonite clay or polymers. Its primary uses include lubrication of pipe and downhole tooling, and to transport excavated cuttings. Trenchless methods utilise environmentally neutral drilling fluid products.

Commonly referenced during HDD operations, the Bottom Hole Assembly (BHA) refers to the collection of downhole tooling on the end of a drill string. They are used to guide, drill, stabilise or condition a borehole. Examples of components include drill bits, steering tools, downhole motors, reamers, stabilisers, barrels or subs.

Technical & Design FAQ

There are a variety of trenchless methods to suit different ground conditions. For example, HDD works well in cohesive clay and sandy soils or rock, while microtunneling is better for mixed or unstable ground.

Alignment selection is largely dependent on construction corridor easements and an assessment of existing structures, services and features in the area. Depth of crossing is dependent on a variety of inputs including, gravity flow requirements, pipeline pressure capacity, and risk mitigation.

Through advanced guidance systems like gyroscopic steering, laser guidance, or wireline tracking.

There is no short answer here 🙂 Contact us to discuss further as capacity varies by method, ground conditions and recommended bore length will decrease with increasing pipeline diameter. The HDD method enables the longest pipeline installations, current records are over 5km long.

Enveloper pipes may be used to encase a carrier pipeline or a bundle of smaller pipes. They may be utilised if the carrier pipeline is not able to withstand externally applied loads, if the carrier pipe does not have the capacity to be installed via the trenchless method or to minimise the number of bores required. Note, while enveloper pipes are typically used to reduce risk, it is not recommended to use envelopers in all cases as the increase in bore diameter may increase other construction risks, as well as project cost and duration.

Often trenchless methods rely on an annular space between the borehole and the product pipe to minimise friction and install the pipe. After construction completion, surrounding geotechnical material may settle into this space or active groundwater may run along this path. Typically surface settlement is negligible, contact us for settlement analysis. For sensitive assets, grout may be pumped into the annular space to mitigate subsidence risks.