Illustration of Trenchless and Open Cut Methods

Measuring the Benefits of Trenchless

Since the various trenchless methods of construction started to become accepted in the last 40 or 50 years, the industry has argued that trenchless can help society by reducing traffic impact, public disruption and the resulting devaluation of the asphalt from trench cuts.

The question always remained: How do you measure this advantage, remembering the business adage is, “If you cannot measure, you cannot manage?”

In 2007, legislation was brought in to lower carbon emissions by British Columbia, many other provinces of Canada, California (Assembly Bill 32), and 39 states in the United States, as well as other areas of the world. The British Columbia trenchless industry tried to work this to its advantage and promote the use of all types of trenchless construction over traditional open cut construction.

One of the groups leading the charge in the province is the British Columbia chapter of the North American Society for Trenchless Technology (NASTT-BC), which developed a trenchless protocol to allow anybody using trenchless techniques – as opposed to traditional open cut – to create a carbon credit.  This will allow cities to offset their trenchless programs against their day-to-day operations, adding a significant benefit to trenchless. NASTT-BC hopes to have this protocol accepted by British Columbia’s provincial government in 2015.

Climate Change and Skepticism

Stepping back to look at the claim that Earth is warming (climate change) is a contentious issue; however, it is based on a century of robust and well-validated scientific investigation. In addition to the American Association for the Advancement of Science (AAAS), the National Academies of Science in the United States, the Royal Society in Great Britain, and the national academies of science in almost all developed and developing countries, have all reached the same conclusions on climate change and the warming of the Earth.

The changes we are inflicting on our climate are creating challenges to the vulnerable populations in the developing world: witness the floods in Pakistan and China, droughts in southern Africa, the Arab Emirates, Australia, southwest United States and India.

Carbon in our Atmosphere

The amount of carbon found in our atmosphere is at levels not seen for hundreds of thousands of years. It should be obvious that releasing this amount of extra carbon in to the atmosphere must have an effect on our climate. The carbon released because of burning fossil fuels is far above what would be released naturally by the processes of normal decay.

It is not practical to stop the use of fossil fuels, as this is likely to decimate our respective economies, but we can make changes that will not only help reduce our carbon emissions but also maintain our economic livelihoods. Trenchless technologies offer a way to help achieve our carbon reduction goals while at the same time helping to maintain our existing lifestyle.

Trenchless activities form only a tiny fraction of global carbon emissions but reducing them can contribute nevertheless. The battle to reduce our carbon emissions will be won by winning many small battles over time.

Carbon Reduction Methods

Emissions to the atmosphere are distributed worldwide in a matter of days or weeks by wind and air currents; therefore, emissions are not an agglomeration of individual national issues but a global phenomenon. Yet most governments still view carbon reduction only on a national level, which makes change difficult without total world agreement.

As countries such as China and India move up the ladder of economic development and increase their emissions, the developed world looks on warily, not wanting to handicap itself by reducing its carbon emissions before India and China do. This is why developed nations have difficulty in agreeing to reductions in their carbon emissions.

Trenchless offers ways of installing utilities that emit far less carbon and that is why NASTT-BC is offering its carbon reduction strategies as an open source to anybody. In fact, NASTT as a whole adopted the concept, as well as the British Tunnelling Society, the Pipe Jacking Association and other bodies in various countries.

Trenchless and Lower Carbon

How can trenchless offer a way to a lower carbon footprint?

First, what is it that the industry does? We install underground conduits, pipes that provide us with potable water, power, gas and information and remove our waste liquids. This leads to the next question: How can the industry continue to install these conduits, use less energy and yet achieve the same results? It’s questions such as these, which prompted NASTT-BC to explore the concept of linking trenchless technology with lower carbon emissions.

The process of installing a pipe underground using open-cut methods involves saw-cutting the asphalt, removing it and taking it to a recycling depot. Workers excavate a trench wide enough to allow safe access for pipe installation, and normally much wider than that required for the conduit and move the excavated material to a dump. The next step is installing the pipe, backfilling the trench with new granular material mined from a gravel pit, compacting the granular trench material to achieve the required density and repaving the trench.

For every 1 km of 2.4 m-deep sewer installed using open cut, around 1,100 loads of material are generated. That is a huge amount of material when you think of how many of these trenches there are in the average urban environment. By using trenchless, we eliminate or greatly reduce the energy to dig these trenches in order to install the utilities we need for modern life.

The question is: Can we install or repair a utility in a less disturbing way? The answer is yes. In general, trenchless construction allows the pipe to be installed or rehabilitated without the laborious sequence outlined above.

Figure 1 clearly demonstrates the benefits of trenchless. On the right, is an open-cut trench where the amount of material to be removed is up to 100 times the pipe diameter; on the left, is the trenchless option, using horizontal directional drilling, showing an excavated area of around 1.5 times the pipe size.
How many of us stop to think about this?

Carbon Calculators

Once it is demonstrated that trenchless moves a lot less material, how does the industry translate this major benefit of trenchless vs. conventional open cut?
In 2009, NASTT-BC developed a calculator through the Adaptation to Climate Change Team (ACT) of Simon Fraser University, Vancouver. This finally caught the attention of the NASTT Board, which took the concept and are now developing its own calculator.
These calculators allow designers to know, with some certainty, the different emissions resulting from alternative methods of construction. Just as with all estimating tools, the resulting calculations are not definitive and the results can only be used to assist decision making and not to differentiate in strict tendering.

The Carbon Protocol

By developing a carbon profile, the industry can really demonstrate the benefits of trenchless technology and show solid evidence of the carbon saved, rather than potentially saved. In 2009, the British Columbia government introduced a tax on carbon emissions that was to provide funding for carbon saving strategies. The Provincial government led by achieved carbon neutrality in 2010 in its day-to-day“operations.

The cities in British Columbia agreed to be carbon-neutral in their day-to-day operations from 2012 on and became eligible to collect some of this carbon tax to assist their budgets.

To assist cities in becoming carbon neutral, British Columbia developed a guideline that assisted in the calculations required for carbon neutrality.

Because construction (capital works) fell outside this requirement, any carbon savings achieved in construction could be eligible for conversion to carbon credits. However, to establish a mechanism to develop carbon credits requires guidelines. In British Columbia, this is called a project profile.

Being aware that trenchless construction emits far lower amounts of carbon is fine, but the major benefit is being able to translate this reduction into an actual carbon credit. This can be achieved under the guidelines of the Carbon Protocol, developed for NASTT-BC by Habitat Carbon Assets in accordance with the following standards:

  • Annex A of ISO 14064-2

  • WRI/WBCSD GHG Protocol

  • Canadian Federal Draft Guide for Protocol Developers

  • The System of Measurement and Reporting for Technologies (SMART)

The protocol is available on the NASTT website,, which is becoming the focus of the industry’s efforts on carbon reductions issues in trenchless construction.

Work Still Required
The carbon protocol has been accepted by the municipal governments of Greater Vancouver and NASTT-BC is working to have the protocol accepted by the province of British Columbia.
Because trenchless emits up to 90 percent less carbon than traditional open cut, it will hopefully become the default method of utility repair and installation of the future. Carbon calculators provide designers with the ability to estimate the differences between open cut and trenchless construction. The protocol will allow the actual ‘as-built’ difference to be known and counted.
David O’Sullivan is owner of PW Technologies and is past chair of the NASTT-BC Chapter.
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