Carpentaria Shire Council Director of Engineering Matthew Fanning says that contractors faced many challenges during the $A1.7 million repair of the pipeline, which runs from Normanton to Karumba.
“The project had to be completed in some of the most trying conditions and time constraints due to the emergency at hand. This flood event was the second largest on record. At the time, both Karumba and Normanton were completely isolated from each other and the broader region. The only means of transport was via boat or helicopter.
“The flow of the flood caused erosion on the banks of the river, which undermined the anchor blocks of the existing pipeline. This caused the pipeline to move and a breach occurred in the pipeline.”
Investigations into the location were hampered by two metres of crocodile-infested floodwaters. At one stage, ping pong balls were unsuccessfully placed into the pipeline to try and confirm the area damaged by the Norman River.
“The river was acting as a reservoir with an open pipe on its bed with a nine metre head. At this stage, pressure tests were not possible as the values were still under floodwaters.
“Equipment was slung out via helicopter to pressure test sections of the pipeline. The failure was eventually identified in the Norman River spanning some 500 metres in length and nine metres deep,” Mr Fanning says.
State of emergency
JR & LM Trackson and other contractors were engaged under the emergency provisions of the Queensland Local Government Act to provide urgent excavation works and transportation services, with the Queensland Department of Primary Industries and Environmental Protection Agency providing support with necessary approvals obtained during the construction phase, so as not to delay the reinstatement of the water supply.
Meanwhile, the Australian Defence Force established a temporary water treatment plant in Karumba to supply its 600 residents with up to 400 kilolitres of water per day during the repairs.
Accessing the site
The scope of repairs involved gaining access to the site of the river crossing, on both sides of the river, to replace a
560 metre section of 250 mm diameter water main with 315 mm PE pipe using directional boring approximately seven metres under the riverbed.
“The only way to repair the pipeline was to replace the existing main by directional boring a new pipeline under the river bed. The contractors used for this project were chosen on the ability to start work in the quickest possible time and from reputation of their quality of work,” Mr Fanning says.
Environmental factors were also a key consideration in using horizontal directional drilling (HDD).
“The environmental benefits of the method of installation of the new pipeline meant minimal environmental disturbance.
“The original pipeline was placed on the bed of the river utilising dozers and resulted in significant damage to the surrounding mangrove environment, river bed and banks,” Mr Fanning says.
A barge was used to overcome the issue of access, carrying JR & LM Trackson’s Vermeer D330x500 HDD rig to the repair site on the Normanton side of the river. Meanwhile, helicopters would airlift the rig onto a high ridge on a local property on the Karumba side.
“We were then able to walk the 330 in there and set up on bog mats. Because the 330 is self-contained, all you have to hook up the hose and you’re ready to drill,” says JR & LM Trackson owner and Managing Director Jeff Trackson.
Mr Trackson also says that the project was extremely challenging. “Yes, there was a high content of salt in the water, as it was very close to the ocean. This made tracking [during repairs] difficult, so our remote steering tool was used.”
The contractors began repairs to the pipeline in March and completed the project on 5 May 2009, with the water pipeline commissioned two days later.
Drilling experience shines through
Mr Trackson has been using Vermeer equipment for more than ten years and highly recommends the equipment and services.
“I bought my first drill – a D16-20 – from Vermeer, Brisbane, in February 1999. With a ll the drills, ploughs, trenchers and vacuum tanks I have purchased, the team at Vermeer have gone out of their way to make sure my operators know what the machines can and can’t do. I would strongly recommend them to anyone in the industry or about to enter the industry,” Mr Trackson says.
Mr Trackson has also used the D330x500 Vermeer rig in subsequent projects.
“The drill is doing great. There was no trouble doing the water pipe in Karumba, as well as a 600 metre shot under Cattle Creek, which is a large flood plain, for Telstra’s optic fibre, which was washed away in the floods.
“We also have six large diameter bores, one being used for 600 mm x 300 metre river crossings for Tenix Alliance in Mackay,” Mr Trackson says.
A legacy of skills
The Karumba Water Supply Pipeline repair project was nominated for an Institute of Public Works Engineering Australia Queensland Excellence Award, which Mr Fanning says is a great acknowledgment of all stakeholder efforts at the time.
“This was an outstanding achievement considering the challenges encountered such as no vehicular access, continual work site flooding and unstable ground conditions. The repair of such a critical piece of infrastructure has provided for a legacy of skills, knowledge and capacity.
“The staff who assisted with the failure investigation and repair have gained significant skills and knowledge in fault finding and repair techniques.”
Mr Fanning says that measures have also been taken to better map and isolate different sections of the pipeline, which remain vulnerable during the wet season.
“The replacement of the water pipeline has resulted in the removal of the highest risks of failure during natural disasters. The new pipeline has been placed seven metres under the base of the river to ensure protection from future flood events.”
