There is increasing awareness among infrastructure asset owners that horizontal directional drilling (HDD) can provide an effective whole-of-life solution for the installation of pipelines.
Maxibor chief executive officer (CEO) and owner Rodney O’Meley provides insights into maxi-rig spreads and highlights their benefits on major projects across the various infrastructure sectors.
Maxi-rigs are HDD rigs required for the installation of pipelines with diameters between 400 mm and 1200 mm, and rated for more than 45,359 kg of thrust and greater than 9,072 kg of torque. There are four maxi-rigs in the Maxibor fleet: a Vermeer 330×500, American Auger 660, Gallagher 600 and Gallagher 660e.
The maxi-rig spread is a significant investment as it comprises much more than just the rig. A spread includes drill fluid cleaners, high volume pumps, a mud mixer, vacuum trucks, rods, tooling and excavators. All add to the onsite cost of a spread, even before a rod is turned. The purchase cost of a new spread today would not leave much change from $8 million.
The mobilisation and demobilisation can require as many as 20 loads for a prime mover and trailer, which, over long distances, can pose a significant cost. A container of spare parts is also an essential part of the spread to minimise downtime and maintain productivity especially in more remote locations.
The knowledge and capacity of the HDD industry to take on more challenging projects in Australia is certainly there particularly where you have very experienced design and construct HDD providers like Maxibor. This enables the integrated body of knowledge required to deliver the project to be involved from early design through to delivery and final commissioning and testing of the pipeline.
The length and diameter of pipelines that maxi-rigs can install will depend on the ground conditions and the pipe being installed. While they have the capacity to drill pipelines of more than 2 kms with diameters up to 1.6 m, typically maxi-rigs are used on projects around 500 m with bore diameters of + 600 mm.
Maxi-rigs are ideally suited for river crossings, ocean outfalls, hard rock conditions and multiple service bores requiring larger diameter holes. Distance is not a problem and neither is force, as the power of the maxi-rigs and the pumps are more than sufficient to overcome the most difficult ground conditions, bore lengths or other design constraints.
Bore hole assembly (BHA) selection is also important as this will drive the rate of penetration of the drill head. Less stable ground conditions such as water charged sands and cobbles are overcome with good practice drill fluid management and, if necessary, the use of casing to support the bore hole.
Maxibor used its Vermeer 330×500 maxi-rig on a 1.320 km Logan City Council project, which connected the Greater Flagstone Priority Development Area with the Cedar Grove sewerage treatment plant. Maxibor designed and delivered a 1.320 km bore, installing 500mm of PE100 HSCR PN20 to a depth of over 50 m.
Maxi-rigs proved essential to the fleet on a project to install a new 400 m section of water pipeline between Lamb and Macleay Islands in Queensland. Maxibor used one of its Vermeer 100x120s to complete the pilot hole and most of the reaming. The Vermeer 330×500 maxi-rig was then brought in to ream the bore hole to a 550 mm diameter and pull the DN400 PN20 pipe through.
Into 2022, Maxibor has several bores lined up for its maxi-rigs with distances in the 1.5 km to 2.5 km range. It is also working in the early design stage with various asset owners and principal contractors on other projects across Australia involving complex river and harbour crossings and outfall project challenges.
Maxi-rigs are selected for their ability to provide solutions to challenging infrastructure installation problems. Industry experts expect these to come to the fore in the current decade as climate change mitigation and adaptation measures grow increasingly necessary to protect against impact of severe climate events.
Electricity, telecommunications, water, sewerage and gas assets will be increasingly impacted by wind, fire, flood, erosion, drought and inundation. Many of these assets are vulnerable because of their age and above ground replacement or trenching is no longer a medium-term viable option.
With the ever-increasing congestion of utility services in metropolitan areas, the difficulties around installation are ever increasing. Maxi-rigs provide an ideal solution for installing new infrastructure assets such as data lines, charging stations and green hydrogen.
An exciting recent addition to the Maxibor fleet has been its electrified Gallagher HDD660e maxi-rig, informally known as ‘The Hulk’. The electrified spread comes with its own substation, which also connects to two powerful Gardner Denver PZ9 pumps and a large Gallagher mud recycling system.
The Hulk can drill up to 3 kms in a single shot with a diameter up to 1.6m. According to the company, electric spreads are the direction of the future for the HDD industry as it responds to the need for emissions reduction.
For more information visit the Maxibor website.