HDD
Cleaners at Logan site .
Maxibor grows its maxi-rig fleet Maxibor’s fleet of maxi-rigs is designed to tackle drilling lengths of more than 1 km, and in challenging conditions such as river crossings and ocean outfalls.
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here is increasing awareness among infrastructure asset owners that horizontal directional drilling (HDD) can provide an effective wholeof-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 330x500, 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,
Logan site with drill and tanker.
36 TRENCHLESS AUSTRALASIA DECEMBER 2021
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 330x500 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
