Private Water Plant Completed in Sydney

After a less than three-year procurement, design, and construction effort, the Prospect Water Filtration Plant in Sydney, Australia was completed late in 1996. The plant was developed under a 25-year build/own/operate (BOO) contract between the Sydney Water Corporation (Sydney Water) and Australian Water Services, a consortium of Australian, US, and French water-focused service companies.

Sydney's drinking water system serves 3.7 million people through nine major storage dams, 159 pump stations, 259 service reservoirs, and 20,000 km (12,428 miles) of water mains. Average consumption is 1,571 Ml/d (415 mgd). To date, through catchment and storage management policies and disinfection (with chlorine and chloramines), Sydney Water was able to supply Sydney with safe water. After heavy storms in 1989, 1990, and 1991, the water supply was high in turbidity and was not consistent with customers' expectations.

This deterioration in water quality was caused by urban growth in the catchment areas, heavy rainfall, increased demand, and limited options to manage incidents of high turbidity without an effective barrier such as a filtration plant.

Filtration needed
The decision to require filtration or its equivalent for all supplies meant that new filtration plants had to be built for the Prospect, Macarthur, Illawarra, and Woronora water supply systems (95 percent of Sydney's supply.) The Prospect Water Filtration Plant, located 30 km (19 miles) west of Sydney on Prospect Reservoir, provides more than 80 percent of Sydney's drinking water.

In 1991, the total capital outlay for adding filtration to all facilities was estimated to be $850 million over eight years. This placed a substantial burden on Sydney Water, which during the same time period was faced with a $6-billion bill for upgrading its wastewater infrastructure.

After considering a number of factors and considering Sydney Water's heavy capital commitment to environmental protection, planners concluded that Sydney Water's customers would benefit from pursuing private-sector involvement in building, owning, and operating the proposed water treatment plants. Early in 1991, after confirmation and approval of the decision to pursue a build-own-operate process, Sydney Water turned its attention to providing extensive information to potential bidders.

Australian Water Services (AWS) was created in July 1991, shortly after the call for expressions of interest in BOO contracts issued by the Sydney Water. AWS's strategy to win the bid for the Prospect plant was to concentrate the best of its internal resources and to hire skilled advisors. The key players in AWS are France's Lyonnaise des Eaux and two Australian companies, P&O Australia and the Lend Lease Corporation. The design component of AWS was made up of Australian consulting engineering companies supported by US firms. Australian firms Sinclair & Knight and Camp Scott Murphy established the Prospect Water Group and linked themselves respectively with US firms Montgomery Watson and Camp Dresser & McKee.

Once AWS was selected from the three final bidders on the Prospect Plant, it took another year before contract documents were signed because of the complex environmental assessment and public consultation processes. Final approval occurred in November 1993 and work on the final design started almost immediately.

Plant design
The Prospect plant has an initial capacity of 3,000 Ml/d (780 mgd) and can be expanded to 4,200 Ml/d (1,090 mgd). Pre-filtration processes include oxidation of manganese using lime and potassium permanganate, pH adjustment using lime or suphuric acid, prechlorination, and coagulant dosing and flash mixing of a filter-aid polymer.

The plant's filter process design comes from Degremont, and the double-cell filters operate at 25 m/h (82 f/h). At the first stage, there are 24 filters, each with an area of more than 230 sq. m (2,560 sq. ft). At the ultimate stage of 4,200 Ml/d (1,090 mgd), the number of filters will be increased to 32. In addition, the process train has been designed to allow the future inclusion of a pre-ozonation stage, should the necessity arise.

The filtered water flows into two clear water tanks having a total capacity of 149,000 m3 (36 million gallons). The tanks are made as lagoons with a membrane lining for the floor and a floating membrane for the roof. Post-filtration treatment includes pH correction, chloramination, and fluoridation, according to Australian drinking water standards.

BOO advantages
BOO projects offer several potential advantages if they are economically and environmentally justified and properly managed. By their very nature, these projects are complex. They require comprehensive and rigorous analysis and coordination if the potential benefits to the community, the client, and the private firm are to be realized. This disciplined approach is needed to help provide the foundation for a sound long-term relationship between the client and the private firm. Turnkey, design-and-build projects, and operations contracts do not impose the same level of discipline on the parties and are thus unable to provide the same overall result.

Specific advantages of BOO projects include:

• Focused planning can lead to efficiencies because the client is forced to fully consider and identify its output requirements and the private firm must plan and coordinate all project phases, including investigation, design, construction, commissioning, and long-term operations.

• Potential financial benefits include the facts that the provision of capital funds by the private firm can enable earlier service to the community and that detailed cost assessment of all project phases can lead to innovative decisions relating to capital versus recurrent expenditures.

• Risk management is enhanced because risks are fully assessed through all phases of the project, resulting in allocation of each risk to the party best able to manage it. Both the client and private firm are forced to address all issues and to consider their relationships throughout all project phases.

• Technology benefits include the ability to mobilize technology and skills normally not available locally and the potential for increased operational efficiency.

BOO projects may develop as a result of either private-sector initiatives or unsatisfied public need. Water infrastructure projects generally fall into the second category. In such cases, it is incumbent on the responsible authority to undertake sufficient investigative work to ensure that bidding is competitive and that the BOO process is appropriate to the need and economically justified. Provided with adequate information, specifications, and a competitive environment, the private sector can deliver the most appropriate, cost-effective, and innovative solutions.

Successful BOO package for Sydney
Teamwork among designers, builders, operators, project managers, and financiers to develop a competitive BOO package for Sydney Water's filtration plants has generated unprecedented synergy. Drinking water for Sydney is being treated sooner and delivered more economically than it would have been without this contract. In this case, the Prospect Plant was brought on line less than three years after the contract was signed by AWS. (Contract was signed on 10 September 1993; operation started on 13 August 1996.) In a traditional process, it could have taken anywhere from four to 10 years.

About the Authors: Ken Waterhouse is with the consulting engineering firm of Montgomery Watson. Pierre Alla is on the staff of Australian Water Services.

Editor's Note: This article was published originally in the 1997 Yearbook of the International Water Supply Association and is reproduced here with permission. The IWSA is headquartered in the United Kingdom with offices in London.