From the magazine

Why trenchless is the ‘green’ choice

There are a number of reasons why Trenchless Technology is a sustainable and greener alternative. Trenchless industry representatives are working to identify and quantify the ecological advantages of selecting trenchless techniques. This can assist suppliers and contractors in arguing for a certain technology.

Easy being green

As well as reducing carbon emissions and inventing innovative solutions for the urban environment, trenchless techniques are equally capable of protecting sensitive natural environments. Trees and root systems are usually unaffected, especially in comparison with trenching.

Pipe and conduit networks are frequently required to traverse shoreline, wetlands and rivers. As sensitive areas are not dug up, pristine marine areas are protected. This is demonstrated by the use of microtunnelling on the installation of pipelines associated with Sydney’s desalination plant. The southern shore of Botany Bay contains extensive seagrass beds, which are a valued and protected part of the estuarine environment.

Trenching through these seagrass beds would have required a seagrass management plan to be implemented during and after construction, and a compensatory seagrass package involving steps like transplantation. Instead, Sydney Water selected microtunnelling from the Silver Beach construction area under Botany Bay for a distance of about 800 metres in order to protect the seagrass.

Calculating the benefits

Using installation and repair techniques such as microtunnelling, horizontal directional drilling, CIPP, pipe bursting and other relining methods can result in a reduced social impact in urban areas. Traffic delays are reduced, and where road traffic is impacted, it is generally for a shorter period of time than with open-cut installation and rehabilitation. As well as increasing the liveability of our cities this also reduces emissions caused by traffic delays and can also reduce the emissions produced on the job site.

Research conducted by the University of Waterloo, Ontario for the NASTT identified two areas of difference whereby trenchless and open cut differ in the production of greenhouse gas emissions.

* Increased fuel consumption due to traffic delays and increased travel distances for detours;
* Fuel consumption of construction machinery and equipment involved in excavation, compaction, backfilling, and re-paving operations.

The preliminary analysis found that the use of trenchless construction methods can result in 78 to 100 per cent lower greenhouse gas emissions than open cut pipeline installation methods. The reduction in emissions associated with trenchless construction are achieved mainly due to its shorter job duration using less construction equipment and limited or no disruption to traffic flow.

Dr Sam Ariaratnam, a specialist in technology such as horizontal directional drilling, outlined the green credentials of trenchless methodology at the 8th National ASTT Conference and Exhibition.

People worldwide are grappling with the effects of climate change. An emissions calculator tool has been developed to enable the comparison of the environmental impact of different utility installation methods.

Dr Ariaratnam said “The construction industry, which consumes a large quantity of fossil fuels, has been tasked with reducing airborne emissions. The use of traditional open cut methods and equipment for the installation of underground utilities has been a common practice in the construction industry for decades. Recently, there has been a growing trend towards adopting minimally-intrusive trenchless methods, particularly in congested urban environments. Recognition of the urgency to curb emissions worldwide has led to an increase in research efforts aimed at developing methods to quantify and reduce emissions.

“Current carbon quantification approaches focus mainly on the effect of added emissions due to traffic delays during construction road closures. While these models provide excellent information, it is imperative that competing utility installation methods also be assessed to determine their “÷environmental friendliness’.”

As a result, Arizona State University and Vermeer Corporation developed a commercially-available emissions calculator tool called ‘e-Calc’ to aid stakeholders in calculating and comparing anticipated emissions between competing technology options. “Now we actually have a way of calculating the sustainable solution,” said Dr Ariaratnam.


Trenchless techniques reduce traffic congestion and disruption and minimise the excavation required, reducing energy consumption.

The protection of marine, bushland and other waterways, not to mention landscaped gardens and yards, are all in a position to benefit from the ongoing promotion of the various innovative trenchless solutions to the relevant authority.

In Australia, the trenchless industry needs to take advantage of the move towards sustainable construction practises and promote these greener credentials to governments and the community at large.

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