Considerations for large-diameter utility HDD work in metro areas

Vermeer Australia dealer can help you prepare for your next large-scale HDD project with advice and machines.

Many utility companies and local governments opt for trenchless construction instead of open-cut work in busy urban areas when upgrading water, wastewater, gas and electrical transmission lines. 

However, according to Vermeer, there are planning considerations operators and project managers need to consider for this specific type of work.

Space limitations

When working in more congested areas, having enough space for all the machinery needed to execute a large-diameter bore is one of the most important factors to consider ahead of time. If there isn’t enough room, contractors may have to evaluate everything from using a drill with a smaller footprint to adjusting the way some of the support equipment is used on the project. 

Maxi rigs that have an onboard cab and 20-foot (6.1 m) rod rack are a good option for these types of projects because they are much more compact than many of the drills used on oil and gas projects. However, crews may spend more time making and breaking rod connections, which may add extra time to the job. Also, crews may have to move their mud recycling systems to a separate location if spacing is too tight. For these reasons, the square footage of the jobsite can have a huge impact on how long a job will take.

On the exit side of the bore, available space will be determined if there is room to lay out piping ahead of pullback or if it will need to be added a section at a time.

Jobsite logistics

The site’s specific location is important, too, since there can be less flexibility for setback distances in metro areas. To maintain the drill pipe and product bend radius, crews may need to make adjustments to the entry angle, which can take a lot of planning and prep work to build up a pad to accommodate the right angle.

The site’s location can also impact getting machinery and workers to the job every day and dictate the need for additional crews to do tasks like directing traffic. Contractors need to make sure they understand local street weight limits because they may need to make more trips or obtain special permits to bring the machinery needed for the job.

Fluid management

Identifying a nearby water source and the closest disposal site, as well as thinking through fluid management is another important consideration. Space on each end of the bore may determine where a crew can set up a reclaimer. However, whether the fluid is being recycled on the entry or exit side, there needs to be a plan to get it back to the drill. In some cases, it may be able to be pumped back, but if there are above-ground obstacles like roads or buildings, that’s not always possible. In those instances, contractors may need to truck it back and forth.

It can be common to establish a separate mud management site when there isn’t enough room to reclaim used drilling fluids on either side of the bore. Using vac trucks, crews will bring used slurry to the mud management site to clean it, then use water trucks to bring it to the drill.

Local restrictions

Occasionally, HDD crews may have to erect sound barriers to adhere to local noise restrictions. Additional equipment like fans to circulate the air within the walled-off area may also be required to help with noise management.

In addition to noise limits, traffic restrictions and fluid management guidelines, LGAs may also have policies that can do everything from limit a crew’s hours of operation to deliver as-built bore profiles for future expansion. Every situation is different, which is why it’s so important to try to sort through those details ahead of time.

From planning support to on-the-job support, your local Vermeer Australia dealer can help you prepare for your next large-scale HDD project with advice and machines. 

For more information, visit Vermeer Australia.

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This article is featured in the September edition of The Australian Pipeliner.

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