Six Amazing Projects in One – Victorian Desalination Project

Thiess

Located near Wonthaggi, on the Bass Coast south-east of Melbourne, the A$3.5 billion mega project is the product of a Public Private Partnership (PPP) between the Victorian Government and AquaSure. The Thiess Degrémont Joint Venture (TDJV) was contracted to design, construct and commission the project.

In December 2012, the plant achieved the completion milestone of Reliability Testing Finalisation (RTF). To achieve this, it operated continuously at full capacity for 30 days, producing drinking water at the rate or more than 410 million litres per day, equivalent to 150 billion litres a year. The water was delivered 84 kilometres up the 1.9 metre diameter pipeline to Melbourne’s Cardinia Reservoir.

The largest desalination plant in the Southern Hemisphere, it was conceived as an emergency water supply response to the worst drought in Victoria’s history but mother nature had much more in store for the construction phase.

As work got underway on site in late 2009, years of extreme drought suddenly came to an end and the project was plagued by one of the wettest periods recorded in the Bass Coast region. Worse still, extreme high winds made it unsafe to operate cranes for weeks at a time.

Against this background of extremes, the completion, less than six months behind the original schedule, was a truly remarkable result for the joint venture. Project Director and now Thiess’ Executive General Manager Construction John Barraclough is full of praise for his team.

“The workforce, the staff and the senior management have all pulled together and we have achieved record timing in the commissioning of a complex plant like this,” Mr Barraclough explains.

“We achieved Preliminary Commercial Acceptance on 29 September and achieved RTF less than three months later which was a marvellous achievement.”

It’s difficult to appreciate the scale of the project without visiting it but some of the statistics are compelling. To begin with, there are multiple major projects within the one mega-project. These include two major tunnels. Constructed by Thiess’ tunnelling team using two tunnel boring machines, the 1.2 kilometre inlet and the 1.5 kilometre outlet tunnels are four metres in diameter and are segmentally lined.

In a major marine project, two large inlet structures and two outlet structures were constructed and then had to be joined to their respective tunnels.

The 84-kilometre delivery pipeline to Cardinia Reservoir was in itself a major project, as was the 87-kilometres of underground power supply which is the longest underground power supply of its type in the world. The pipeline and power supply were also accompanied by three fibre optic cables for systems monitoring.

Beyond the desalination plant itself, there was also a huge environmental undertaking to rehabilitate the surrounding land. Much of the site was once cleared for mining and farming, and the sand dunes were also degraded or had been removed entirely.

A total of 225 hectares of land surrounding the plant has since been rehabilitated in one of the largest ecological restoration projects ever undertaken in Victoria. This involved reinstating the dune system, and the creation of wetlands, coastal and swampy woodlands, and new habitat for local fauna. This project involved the planting of 4 million new plants and 150,000 trees.

The enormous reverse osmosis (RO) building is a feat in design, featuring a unique green roof. It has living camouflage made up of 100,000 carefully selected local indigenous plants which are now well established, ensuring the building blends into the surrounding dunes. At 26,000 square metres, it is the largest green roof in the Southern Hemisphere and slightly larger than the footprint of the Melbourne Cricket Ground.

Inside the RO building there are more than 8,000 RO tubes containing a total of 55,000 RO membranes.

Seawater flows via the inlet tunnel into the Sea Water Lift Station where it is lifted into the plant by submersible pumps. It is first filtered under pressure through 72 large dual media filters. When the filtered water enters the RO stage, its pressure is elevated to an incredible 16 bar or around 940 psi.

To maximise the efficiency of the plant, an innovative energy recovery system harnesses some of the pressure energy from the processed seawater and reapplies it to the process.

After the RO process, the water is so pure it must be then remineralised to become potable water, before it enters the pipeline to Cardinia.

Everywhere you look on the project there are remarkable statistics about which John Barraclough still marvels. “We’ve had something like 17,000 bits of kit we’ve had to connect,” he says, “75,000 cable connections, 1,200 kilometres of various types of cable and 3 million cubic metres of earthworks.

“The achievement is all the more extraordinary when you consider that during the early stages we were doing a lot of earthworks and a lot of concrete works pretty much in the mud, and we had terrible wind conditions. It wasn’t until we got out of the mud that we really had a chance to excel and we’ve taken advantage of that.”

Thiess Managing Director Bruce Munro endorses Mr Barraclough’s assessment. He came to the helm of Thiess just as the difficulties on the project began to impact the bottom line.

“Achieving RTF in December was a phenomenal result and I doubt what they have achieved here could have been matched anywhere else,” says Mr Munro. “They’ve really powered home over the last six months and brought it in on the revised budget that we’d set ourselves.

“Right from the start we knew this project had a very tight time schedule to achieve and while a huge amount of effort was put in up front, the perfect storm developed around us and made achieving that schedule impossible.

“We had so many problems with wet and windy weather. For example, we lost something like 60 days in one period because the wind was too strong to be able to swing the cranes.”

At the peak of construction in July 2011, around 4,500 people were working across the project. In the RO building alone, 800 people were deployed to construct the racks and the complex maze of pipes, valves and instruments.

The commissioning process required a much smaller team of around 200 and they delivered a remarkable result. Engineering and Commissioning Director Omar Shahin says VDP has set a new global benchmark.

“The commissioning has gone very well, certainly compared to other projects of this size. The time from first seawater being lifted to the end of RTF is faster than any other comparable water project in the world,” Omar explains.

“Commissioning has gone as well as it has because we stand on the shoulders of construction and the quality of construction is very good.”

Of course, Omar has his own set of statistics to make the mind boggle at the scale of the commissioning task. “This is a large project. We have something in the region of 570 pumps, more than 18,000 valves and more than 8,000 instruments. In total, that means we have something in the region of 26,000 individual tests that we have to complete in order to get the plant up and running.

“That involves taking everything from the completion of construction through to making sure that power is widely distributed, making sure that everything is communicating with each other and then getting all the individual components working.

“I can honestly say that from the commissioning perspective, for any organisation wanting to learn some valuable lessons, particularly in the areas of pre-commissioning and construction completion, this would absolutely be a showcase project.”

Bruce Munro believes the dogged determination of the project team comes from the culture embedded within Thiess.

“We are a can-do sort of company and it makes me extremely proud to be part of the Thiess organisation,” he shares.

“When I first got involved on this site back in August 2011 it was obvious that the job was in a little distress, but the turnaround achieved by the team on site has demonstrated that Thiess can-do attitude and that we will get things finished to a high standard no matter what.”

For John Barraclough personally, it’s been a major challenge in a long and distinguished career.

“The degree of difficulty here has probably been the hardest, but I got great satisfaction out of being a part of it and being able to work with such a good team. We’ve had some very good people working here and they should be proud of what they achieved.”

Omar Shahin admits his experience at VDP will be hard to top. “I don’t think you get to do too many of these in a career. It’s been a very invigorating project and I wonder how I’m going to cope when the levels of pressure are not this intense.”

For those who have worked on the project since day one, the sense of achievement is deeply felt.

General Superintendant Phill Robinson walked onto the then vacant farmland back in 2009. “We started with earthworks in September 2009 with a view to pouring our first concrete before Christmas.

“As we drove around this site, it was hard to imagine where everything was going to fit. It was a challenge grasping the enormity of what we were going to do.

“It’s quite magnificent to see what we’ve all achieved here. It just looks fantastic and it really does give you a sense of achievement when you see it now.”

The plant is now in the hands of the Degrémont Thiess Operations and Maintenance Joint Venture.

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July 13, 2020, 11:32 PM AEST