The Lonsdale Lakes Rising Main project, undertaken by the Barwon Water Alliance, involved the installation of 4.5 km of pipeline through coastal salt marsh plains that are classified as being of very high environmental significance.
The project involved the installation of a new, larger rising main to transfer sewage from the townships of Point Lonsdale and Queenscliff to Ocean Grove to accommodate for the expected increase in population in the area. GEM Industrial Services was required to provide continual ‘stringing’ of pipe into 2 km lengths to match the length of the two horizontal directionally drilled (HDD) bores. The HDD bores were long and were further complicated by the inclusion of an “÷S’ bend deviation needed to protect significant environmental sites.
Extensive preconstruction planning and innovative construction techniques were required to minimise impacts on the flora and fauna in the area, as well
as manage the risks associated with high groundwater levels, poor geotechnical conditions and acid sulphate soils.
Due to the project constraints, GEM Industrial Services chose the McElroy T900 butt fusion machine which proved to be not only self contained, self propelled, and self generating, but capable of twice the weld rates of low pressure HDPE welders. Electronic monitoring and data logging of all welds completed was also a key driver in the choice of equipment. The quality of the welds was of paramount importance if the construction techniques that were chosen were to succeed.
GEM innovations
The GEM Industrial Services team devised a number of innovations during their part of the design and construction phase, which included all of the civil works, as well as supply and installation of all pipeline components, valves, fittings and assets.
Installing pipeline in 2 km lengths required some significant advances in installation techniques. At the deepest point, the rising main is approximately 13 m underground. It was decided that each string of welded HDPE would be hydro tested prior to insertion. This was then followed by complete and final hydro testing of the entire pipeline once all sections had been inserted into the ground. The integrity of the pipeline was confirmed with NATA tensile certification for the HDPE welds, followed by rigorous hydrostatic testing of the complete system.
Innovation was also required to mitigate any quality concerns arising from pulling 2 km lengths of DN560 HDPE pipe through a curved bore. Steel posts driven into the ground in a “÷U’ shape and a series of rollers placed in sensitive areas ensured that no damage occurred to either the flora or the pipe string. The pipe was placed on rollers at 12 m spacing and assisted by five excavators during the pull back process.
A water filler line approximately 2 km long was also required to fill the pipe with water as it was inserted into the ground. Water was needed to create a neutral buoyancy of the pipe inside the bore in order to reduce the pull force required to insert the pipe. Hydrostatic testing achieved certification of the pipeline both pre-and post-insertion into the bore.
Once the pipeline was assembled GEM Industrial Services completed all of the dewatering and industrial plumbing works, including live connection of the new 560 mm HDPE main into the existing 426 mm sewer main servicing Ocean Grove.
GEM Industrial Services delivered the completed project on time and on budget, including production of asset registers and as-built documentation.
With all works performed safely to Safe Work Method Statements documentation and task methodologies, GEM Industrial Services are fast becoming a rising star in the delivery of high quality HDPE poly welding services and projects.
GEM Industrial Services would like to sincerely thank its contract partners Ancon and the Barwon Water Alliance for their partnership approach to the commitment and the success of the Lonsdale Lakes Rising Main project.
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