Robinvale project sets the standard for Murray River water supply

By David Palmer

In May Lower Murray Water let a 12 week contract to water and wastewater specialist Port Melbourne company and CCF member JHL Civil Pty Ltd, to survey, design and trench in what LMW calls domestic and stock piping, to about 350 rural landholders in the Robinvale Irrigation District, 450km north west of Melbourne. As well the $500,000 contract called for installing assemblies which include a pressure limiting device, a flow restrictor, a water meter and a filter.
About mid May JHL started contacting landholders to explain the scheme, confirm meter locations and arrange access to instal piping on their properties. That was easier said than done because of the significant number of landholders missing from the database. When Earthmover visited JHL a month into the contract, some landholders were still proving difficult to contact.
Landholder contacts
JHL’s project manager Mick Dunn, had to concentrate his efforts in making contact with landholders to keep in front of the construction crew. JHL also contracted Maloney Field Services from Adelaide to help with the liaison.
The first stage of the project involved trenching in about 10km of 40mm diameter pipe running from the meter assembly supply point owned by Lower Murray Water to the water point – usually a tank - on the private property. The second stage is installing about 17km of pipe on existing road easements. In total pipe sizes are 110mm, 63mm and 40mm in diameter grey water designated polyethylene pipe, depending on design parameters.
Dunn said one of the big advantages of the new piping system is that there will be reduced losses and maintenance as previously. That’s because the pipes are replacing open concrete channels and pipes that had been in use since the 1950 and prone to leakage. Where Earthmover inspected a few, They were obviously prone to considerable leakage given the number of cracks that had been sealed over the last half century.
Constant pressure
The other disadvantage with the channel system was that landowners had to pump out of the channels. Now they will have water supplied under constant pressure at about 2400kPa (35psi).
Craig Draper and his Cotec P/L employees, is the subcontractor trenching in the pipes. He has four Ditch Witch trenchers operating throughout the area including one with a cab for protecting the operator under trees. His biggest is an 85kW RT90H capable of trenching to 1.8m. On this job though the trenches are going in to a depth of 800mm.
Draper starting putting in irrigation lines for grapes and more recently, has worked to pipe water to thousands of hectares of almond trees between Robinvale and Swan Hill. In fact that area grows a wide variety of table grapes, wine grapes, avocadoes, almonds, mangoes and vegetables, including the biggest carrot producer in Australia.
The average sized block in the Robinvale Irrigation District, with most growing table grapes, is about 15ha. They extend up to 5km from the Murray River in area.
Heritage requirements
While the soil is generally fairly sandy and easy to excavate there are cultural heritage requirements to consider. Some pipelines needing to be installed near known aboriginal heritage sites, require restrictions on trench width and depthdictate that trenching is restricted to the right of way in some places as narrow as 12m. Remaining Mallee scrub is also precious and must be retained, Dunn said.
He came to the job with useful experience in negotiating with landholders about pipelines being installed on their properties. Last year he was construction services manager for the controversial Sugarloaf Pipeline, which brings Goulburn River water through pipes up to 1.7m in diameter, into Melbourne
Previously he worked for AJ Lucas on the cross Bass Strait pipeline in Gippsland, Victoria and on preliminary route selection, land holder liaison and risk assessment for a 1000km gas pipeline between Moomba in South Australia and Roma in Queensland.
“So I came on here as project manager because I understand environmental and other restraints a project like this imposes,” Dunn said.
Land owner liaison
JHL Civil, winner of a state CCF Earth Award, has a reputation for successfully managing projects requiring environmental consciousness. The Robinvale one presented a significant challenge because of the timeframe and the significant amount of land owner liaison required.
The company has recently completed 30km of pipelines for the Gippsland Water Factory and that job presented much the same challenges. The company said the Robinvale project aligned well with its direction to further develop itself in the irrigation infrastructure market.
As Mallee farmers enjoy one of their wettest years for decades, precious little domestic and stock Murray River water will now escape into the subsoil and be wasted, on the new network around Robinvale.
More information: www.jhlcivil.com.au, Marcus@jhlcivil.com.au