Trenchless digging or open cut?

Vermeer Australia talks through the different considerations and how environment plays a part when deciding what digging method to use on pipeline construction projects.

The horizontal directional drilling (HDD) industry has come a long way since Vermeer Australia introduced its first rig to Aussie shores in 1991. The equipment, technology and expertise of the operators have all become more sophisticated, which has helped expand the range of projects drills can be used for. However, there is still a significant and growing market for open-cut methods, like trenching and ploughing in the Australian construction industry.

According to Nigel Dobier, Pipeline Sales

Manager for Vermeer Australia, most underground construction projects have a few factors you need to think about when choosing between trenchless and open-cut installation methods. “There are the basics involved in the decision, like equipment, labour and restoration costs, but there is often more that contractors need to consider that impacts the decision,” he says. “Ground conditions, the diameter of the product, grade requirements, underground and aboveground obstacles, as well as location are all other things that come into play.”

Metro installation considerations

In areas with more developed infrastructure, HDD is usually the preferred installation method for small-diameter utilities in urban and suburban locations. Dobier says minimising restoration, avoiding traffic disruptions and keeping residents happy with minimal noise disturbance are a few of the reasons why HDD is used in populated areas.

“Most of the time, drilling a utility line is more cost-effective and takes less time because you go under roads and footpaths, not through. Also, you do not have to deal with above-ground obstacles, like fences, roadways, sidewalks and driveways,” he says.

Rural installation considerations

In regional and rural areas, since there is often less restoration and obstacles to deal with, trenching is typically faster and more costeffective for smaller diameter projects.

According to Dobier, in more wide-open areas, contractors still need to consider which method makes the most economic sense. “Accounting for existing utilities, type of soil, the size of the product being installed, and the required depth still need to be thought through before choosing which method to move ahead with,” he says.

“It may be less expensive to use an open-cut method for shallow installations. However, for deeper installations or in rocky soil conditions, HDD may still be the best choice because less material has to be removed during the installation process.”

Dobier also says even if open-cut methods make the most sense for projects in rural areas, contractors should still consider using trenchless technology for passing under roadways, rivers and other above-ground obstacles.

Large-diameter pipe considerations

For pipeline utility projects including gas, oil or water, a combination of excavating and trenchless methods is typically used.

“Over longer distances, open excavation will typically be more cost-effective than other installation methods, but you should use a horizontal directional drill, auger boring machine or piercing tools to cross under roads, railways and rivers,” Dobier says.

“HDD should also be considered for drilling over long distances or through rock or hard surface conditions. Auger boring machines are a great option for installing large-diameter steel casings over short distances or if there is a limited space that would reduce your setback distance. "Piercing tools are very efficient for boring short distances, and do not require a lot of setup time, which is a huge positive for many time-poor operators.”

Vermeer Australia’s horizontal directional drills are equipped with the features operators need to get the job done and have been fieldtested to demonstrate they can handle the most exacting large-diameter projects. Vermeer Australia’s HDDs are durable, reliable and powerful.

For more information visit www.vermeeraustralia.com.au