A two-pronged Goulburn-Murray Water (GMW) winter works project in Boort will see total bank remodelling and rock armouring along 2.8km of the Loddon Valley Number 1 Channel; and replacement of a 90-year-old syphon which intersects with Calivill Creek.
Project Manager Jarrod O’Brien said the channel upgrades are due for completion early August, and are expected to provide another 80 to 100 years of service from the structures.
“There will be 2000 tonnes of rock armour used to provide protection in the channel and reduce erosion and we have removed a considerable amount of silt from the bottom of the channel,” he said.
Managing Director Pat Lennon said rock armouring is one example of innovation GMW is bringing to its capital works program.
“Our teams have been pursuing this approach as a priority to take advantage of the significant cost savings this provides compared to not rock armouring – we’re talking about hundreds of millions of dollars saved over more than 25 years,” he said.
Field Team Leader Andrew Norris, who is overseeing the work, said despite some foggy mornings the weather had been ideal.
“Customers will definitely get a better flow through here now. It’s been decades since these channels were constructed.
“They were in need of attention.”
Downstream of the channel remodelling, work on replacing an existing irrigation syphon is in full swing, which will see two new 1800mm diameter pipes installed side by side.
A 36-tonne excavator has assisted with lifting the new pipe sections into place which has negated the need for cranes on site.
Once complete, the syphon will be capable of carrying up to 500ML of irrigation flows each day through the Loddon Valley Number 1 channel without impacting on the intersecting Calivill Creek.
Mr O’Brien said the new structure will improve reliability, ensure customers are not impacted during the irrigation season and reduce future maintenance costs.
“As there were a number of leaks in the old syphon, it was due for replacement as part of GMW’s asset management strategy.
“The new syphon has also been designed to not require any headwalls, significantly reducing construction time and overall cost,” he said.
Waste concrete from the old syphon has been transported to a local recycler where it will be crushed and reused for road base and farm laneways.
“This has reduced the environmental impacts,” Mr O’Brien said.
Field Team Leader Matt Sherwood said there were a number of challenges associated with lining up two pipes and it was painstaking work.
“It’s all about the methodology and putting it in properly.
“It’s important to compact the material underneath it. The most critical part of laying a pipe is the haunch zone (the area near the base of the pipe).
“We have used a partially-fluid cement fill between the two pipe barrels to improve efficiency, which has also allowed the pipes to be installed closer - minimising trench excavation,” Mr Sherwood said.
The syphon works and channel upgrades will cost an estimated $1 million in total.