Australia is the driest inhabited continent on earth. Water is seen by government, farmers, planners and environmentalists alike as being the key limiting resource on Australia’s growth into the future.

Sydney Water Corporation’s goals are to provide “sustainable water supplies; clean beaches, oceans, rivers and harbours; wise resource use and smart growth,” and it has a number of projects underway to help achieve these goals. PB is involved with one of the key projects, the Georges River Program.

A primary component of the Georges River Program is a proposed 50-km (30-mile) -long pipeline carrying treated sewage from south western Sydney to the coast through some of the most highly developed parts of the city. Opportunities for reuse of this “recycled water” would be provided to potential customers who currently use large amounts of drinking water for non-drinking purposes, such as in industrial processes, and irrigating parks, gardens and golf courses. New and redeveloped residential areas may also be able to use recycled water for non-potable purposes such as flushing toilets, car washing and garden watering.

Richard Schuil, Planning Manager for Sydney Water, described the project as an “exciting and high profile investment.” The project will cost around A$300 million over the next five years.

Teaming Approach

PB has been contracted to undertake technical investigations associated with the development of a preferred recycled water pipeline route and construction techniques, carry out a detailed assessment of the potential environmental impacts associated with the proposal, and prepare an environmental impact statement and associated technical papers.

Rather than the client-consultant relationship that we usually operate under, our project staff has joined with Sydney Water to form an integrated project team (the IPT) to carry out the project. A designated project office has been established, with Sydney Water staff working side-by-side and in collaboration with PB.¹ This approach was one of the reasons we won the job. Working together this way gets issues resolved quickly and efficiently and is a great way to build a sense of team work.

The IPT members have all signed a charter that illustrates a commitment to team work, innovating for continuous improvement and achieving an enhanced reputation for all participants.

The Need for the Georges River Program

The population of Sydney is growing at a rapid rate. A new person is added almost every 6 minutes and a new dwelling is created approximately every 14 minutes. A lot of this growth is occurring on the outskirts of Sydney in the south and west. For example, the suburb of Hoxton Park has a population of 40,000. In 20 years that population is expected to more than triple to 140,000.

Currently, the sewage from Hoxton Park and the surrounding region is treated at either Glenfield or Liverpool sewage treatment plant (Figure 1). It is then transported via the southern and western suburbs ocean outfall system (SWSOOS) to the Malabar sewage treatment plant on the coast—a distance of more than 40 km (24 miles). The SWSOOS transports the sewage from one quarter of Sydney’s 4 million inhabitants, so at Malabar the sewage is treated again before being released to the ocean.

This system is overburdened, particularly in wet weather when the volume of wastewater arriving at the treatment plants increases by up to three times. In extreme wet weather, excess flow from Liverpool and Glenfield sewage treatment plants and the SWSOOS goes into the Georges River.

As the population of Sydney’s south west region grows, the existing treatment plants and the SWSOOS will not be able to comply with the Environment Protection Authority’s licence conditions, which state:

• There must be no overflows in dry weather
• Sydney Water must maintain existing wet weather system performance and improve wet weather performance where feasible.

Figure 1: Existing (purple areas) and upgraded (blue areas) Sewage Flows

The Georges River Program

Sydney Water’s proposed solution to address these problems and meet its customers’ increasing demands for environmentally friendly practices is being delivered in two stages (Figure 1) to cope with the rapid growth of Hoxton Park:

• Stage 1. The first stage involves new sewer mains from Hoxton Park and a first round of upgrades to both Liverpool and Glenfield sewage treatment plants. Construction commenced in November 2002.
• Stage 2. The second stage involves new gravity-fed sewers for Hoxton Park, decommissioning two sewage pumping stations, overflow abatement upgrading and amplification works at Liverpool and Glenfield sewage treatment plants, and construction of the 50-km (30-mile) -long pipeline to transport treated sewage from Liverpool and Glenfield sewage treatment plants to customers across southern Sydney.

Construction of the recycled water pipeline is expected to commence by 2005 and be complete within three years. Plans call for the pipeline to be built mostly underground and to carry 100 million litres (26 million gallons) of recycled water per day. This would more than treble Sydney Water’s current recycled water provision and bring the total proportion of Sydney’s wastewater that is recycled from around 2.5 percent to 10 percent.

Innovative Construction Techniques

As the pipeline is constructed, off-take valves will be inserted at regular intervals so that as new customers become available, they could be connected easily to the pipeline. Scour valves will be inserted at low points and empty into the nearest sewer, and air valves will be inserted at highpoints along the pipeline.

The problem for the selection of the pipeline route was that it needed to pass across most of southern Sydney. This meant passing down residential streets, through shopping precincts, under rail-lines and rivers and across major traffic intersections. Part of the problem was solved by further innovation in the form of sliplining. This technique has been used many times before, but is by no means a standard construction technique. A disused water main exists for around one fifth of the proposed route under many of the more populated suburbs of Sydney. Sliplining would involve breaking into and inserting new piping into the existing disused pipeline, and would minimise impacts on the surface and provide a minimum of disruption to the community.

The remainder of the pipeline route utilises trenching and boring techniques through lightly trafficked streets and parks and avoids shopping areas. The pipeline would be bored under major intersections and areas of sensitive land use, including rivers and creeks.

Communication

Sydney Water wanted to demonstrate a commitment to building positive external relationships. We assisted in this respect by coordinating an information campaign to determine the concerns of people whom the project may affect.

A number of communication tools were used to present the information to the public. A Web site was established that describes the proposal, and advertisements were placed in local papers across Sydney announcing the commencement of the impact studies. A newsletter about the project was sent to each affected home with a fact sheet describing its neighbourhood in greater detail. The sensitive land users and groups were written to individually to explain how the project might affect them. Community information evenings were held in six venues along the pipeline route. Local councils were met with separately and elected representatives were sent information materials regarding the project. Other groups were met with if they expressed a desire for further information.

Summary

Sydney’s continued growth meant that either re-use was taken seriously, or a new water supply dam would be required. The New South Wales government indicated that it had “deferred indefinitely” the construction of a new dam so the use of recycled water has become an imperative.

The Georges River Program demonstrates a serious Sydney Water commitment to recycled water. It is the most ambitious of Sydney Water’s re-use schemes to date and signifies an approach to water supply problems beyond pipes and pumps. Through its involvement in this project, PB is making a major contribution to Sydney Water’s goal of sustainable use.