Desalination technology has been around for many years and is not the panacea but part of the solution including ground water extraction, rainwater harvesting and water re-use, where traditional surface water supplies have been outstripped by population and industrial growth and climate change.
This example from Australia concerns a very large plant capable of supplying 300 megalitres/day and powered in part by renewables. By contrast, our largest plant is located at Mossel Bay and provides 15 megalitres/day and cost R210 million at the time of commissioning in 2011. New technologies such as home grown eutectic freeze crystalisation (EFC) promise even greater efficiencies and with the cost of wind and solar power declining, the perceived high energy cost of desalination may be a thing of the past. Ed.
In April 2008, Aurecon was engaged to undertake technical studies and investigations for the Adelaide Desalination Project. The initial scope of work included conducting environmental and engineering investigation, developing concept designs for the 100 Gℓ per annum seawater desalination plant and transfer pipeline, and involvement in the environmental impact statement (EIS) process.
The marine and terrestrial environmental and engineering investigation programme that supported the EIS and concept design process was a major challenge. It involved not only Aurecon’s own environmental, geotechnical and engineering specialists, but the management of nearly 50 sub-consultants, procurement of a jack-up barge, and the input of South Australian Water Corporation (SA Water) specialists and external reviewers.
For the pre-construction phase of the Adelaide Desalination Project, Aurecon worked closely, and collaboratively, within a wider integrated project team set up by SA Water. In addition to direct deliverables, assistance was provided to the wider team in terms of the development of the feasibility study, including the business case, plant site selection, pipeline route selection, procurement strategies, and risk management plan.
Aurecon also assisted with the development of tender documents and participated in the bid evaluation process to appoint the consortia and other contractors.
In addition, Aurecon provided the performance-based technical specifications for the plant’s design and construction contract, and associated 20 year operations and maintenance contract, to best meet SA Water’s long term needs across the technical and commercial objectives.
Aurecon provided an onsite technical team throughout the delivery of the project and delivered construction phase contract management, project management and technical advisory services for the project.
The plant was constructed under a design build operate and maintain (DBOM) contract arrangement, with separate contracts for the 13 km transfer pipeline and pump station, power supply infrastructure and early enabling works. Working with the integrated wider project team, the EIS process and approvals, and signing of major works contracts, were all successfully achieved within the tight project timeframe.
The design of the reverse osmosis (RO) system at the heart of the plant allows a high level of plant flexibility and can achieve capacity turn-down ratios to as low as 10 per cent of total capacity with proportional decrease in energy consumption.
Desalinated drinking water was introduced into Adelaide’s water supply network in October 2011 and the plant reached its full production capacity of 300 megalitres a day in November 2012.
SA Water delivered commercial handover of the plant 19 days ahead of schedule, within the original approved budget of AUD1.824 billion (R19 billion today).
The project has received several industry awards including the Project of the Year at the Project Management Institute awards in 2013.