*Last updated 24/04/2019
Installing a sewer line under a railway is no simple task at the best of times.
What if you had just two days to complete it?
Edge Underground found itself in such a position when the Gold Coast City Council asked for a gravity sewer line to be installed via trenchless technology along the Old Pacific Highway in Pimpama, with a section of the sewer line needing to be installed beneath a section of the Queensland Railway. There was one major condition with the project: the railway had to be reopened within 48 hours, ‘no ifs, no buts’.
Steve Mitchell, Project Engineer at Edge Underground, said the company was up to the challenge. Working with limited information about the job site, Mr Mitchell said preparation was crucial to the successful execution of the project.
“Organising appropriate crews for the job was a top priority, as well as selecting the most appropriate tools, materials and drilling equipment,” Mr Mitchell said.
“Contingency plans for changing ground conditions, disposal of drilling mud, mechanical failure and supply of materials also had to be prepared before the works could begin.
“Each aided in the speed and smooth execution of the project, and gave us a clear action plan and backup if something unexpected were to take place.”
Execution and adapting to difficulties
Edge Underground utilised two, four-person crews to complete the installation.
The assignment called for the installation of a DN600 Class 4 butt jointed concrete enveloper pipe around a DN450PE gravity sewer. An initial 350mm laser-guided microtunnel bore was followed by reaming the pilot out to 700mm in diameter as the DN600 jacking pipe was installed. The gravity sewer was then be centralised and grouted within the enveloper.
Upon arrival, the crews were pleased to confirm that the stiff, self-supporting clay in the area meant ground conditions would not be a problem.
Their luck wouldn’t last — at the end of the first day, heavy rains rolled in and persisted for hours. With less than 24 hours left to complete the project, their access tracks to the site had become unusable.
Thankfully, Edge Underground was ready for the worst. Knowing that weather during the night was going to create problems, the team arrived early, and the tracks were able to be repaired with minimal time lost.
“This is where our pre-planning and coordination shone, and we were able to get back to work within a short amount of time,” Mr Mitchell said.
In the end, after 12 hours shifts from each of the crews, the installation was wrapped up on-grade and on time.
“Despite the challenges, we were able to get the project completed both on-grade and within a tolerance of 10mm vertically and horizontally, which is a great success for the team,” Mr Mitchell said.
Expert installations across Australia
Stuart Harrison, Managing Director at Edge Underground, affirms that the team members at the company are what really make the difference on difficult projects when high competence and reliability are essential.
“We have experienced personnel ready to undertake work around the clock, across Victoria, New South Wales and Queensland,” Mr Harrison said.
“This gives us an added advantage when it comes to projects requiring a fast turnaround.”
That dedication, coupled with the pinpoint accuracy of the Vermeer AXIS Guided Boring System and other equipment, give the company everything it needs to achieve consistent success with time-sensitive installations.
“Railway closures are a major inconvenience to communities and businesses, so the ability to get in and out quickly and safely is something that the Edge team can be proud of,” Mr Harrison said.
Wherever you are in Australia, contact Edge Underground on 1300 522 533 (JACKED) to discuss your microtunnelling job.