Trenchless Tunnelling Technology

Aging infrastructure has become an increasingly crucial issue for both developed and developing countries. When this infrastructure is underground and needs to be replaced or rehabilitated, however, access can be a problem: in the intervening years since initial construction, roads, utilities, and other infrastructure have been built above, restricting our options. 

Traditional open-cut construction may not be suitable for pipe replacement or rehabilitation for any number of factors.

Putting our trenchless tunneling technology experience to work for you

WSP has a long track record of successful work with trenchless methods, and we have developed expertise and advanced the state of the art with various trenchless technologies. Using these techniques, we can assess, rehabilitate, or install underground infrastructure with little to no excavation, minimizing the disruption and environmental impact of the project, and reducing the impact on adjoining buildings, structures, utilities, and the public.

Some of our main areas of expertise include:

• Condition assessment of existing pipes and utilities

• Feasibility, conceptual, and preliminary studies

• Detailed design, specification development, and contract administration for traditional and alternative delivery trenchless projects

• Construction support, contract administration, and construction management services for all varieties of trenchless technology project

Condition assessment

The tools used to assess the condition of underground infrastructure, such as underground water or sewer networks include destructive and non-destructive methods, such as acoustic leak detection, closed circuit television (CCTV) for visual inspection, and electromagnetic inspection for wall thickness measurement.

We qualify which method is the best fit for a specific project by reviewing the data collected from the condition assessment and recommend a plan of action that maximizes rehabilitation of the pipeline in question, taking into consideration timelines, budget, and our findings.

Feasibility and conceptual studies

WSP conducts feasibility studies, as well as design and specifications for various trenchless technologies, including:

• Microtunelling

• Horizontal directional drilling (HDD)

• Pipe ramming

• Cured-in- place-pipe (CIPP) lining

• Slip-lining

• Swage-lining

• Carbon fibre reinforced polymer

• Pipe bursting

• Spray-on liners

This has led to several new technologies for new pipes to be installed, or for existing pipes to be rehabilitated using trenchless technologies.

Micro-tunnelling

Micro-Tunnelling is a trenchless solution for constructing small diameter tunnels that is used especially for projects that require the tunnel to cross under dense traffic roads, railways, or rivers. This method minimizes disruptions on the surface during the tunnel construction in comparison with traditional open trench method, and there is no requirement for personnel to be inside the tunnel during construction operations.

Micro-tunnelling can be utilized in a variety of soft-ground or hard-rock ground conditions and the cutterhead is designed for the specific geology anticipated at the site. This technique installs typically concrete, steel or FRP jacking pipes using a pushing or jacking frame within the launch shaft.

WSP has expertise to cover all areas and ground conditions where micro-tunnelling is employed.

Horizontal directional drilling

Horizontal directional drilling (HDD) is a trenchless construction method for installing subsurface piping or conduits by using a surface mounted rig, first to drill a guided pilot-hole along a predetermined bore path consisting of a shallow arc, followed by reaming, swabbing, and then to pull a string of pipe into the borehole.

Trenchless rehabilitation of pipelines

Trenchless technologies for water main and sewer rehabilitation typically includes the installation of a manufactured liner pipe within the host main and/or in-situ spray application of a liner material.

In selecting the preferred method for the rehabilitation, the following considerations need to be taken into account when selecting the rehabilitation methodology:

• Pipe material, internal corrosion and tuberculation, joint failure, and external corrosion

• Operation factors, including hydraulic conveyance limitations and water quality

• Condition of the pipeline foundation and depth of the pipeline and water table

• Hydraulic operating pressure and transient pressure requirements

• Number and type of fittings, including branch and service line connections, valves, fire hydrants, and repair sleeves

• Duration and level of service interruptions, and the provision of temporary service

• Site conditions and factors, including local utilities

• Traffic conditions

The rehabilitation is often done by cured-in- place-pipe (CIPP) lining, slip-lining, swage-lining, or carbon fibre reinforced polymer.