The Glenelg to Adelaide Park Lands Recycled Water Project will have the capacity to provide more than 3.8 billion litres of high quality recycled water per annum. In addition to supplying existing customers, the project will provide a minimum of 1.3 billion litres per annum to irrigate the Adelaide Park Lands.

The works comprise a new 35 ML/d recycled water treatment facility and the storage of 15 ML of treated water on the site of the existing Glenelg Wastewater Treatment Plant (GWTP), a transfer pipeline between Glenelg and the central business district, and a ring main pipeline network around the entire Park Lands.

The project is a key action under the new South Australian Government Water for Good plan, and is being delivered by an alliance between SA Water, United Water, Leed Engineering and Construction, Leighton Services and Guidera O’Connor.

Constructing the pipeline

The City Green Alliance has installed approximately 8.5 km of 750 mm diameter trunk delivery main and around 23 km of ring main distribution network ranging in size from 250–525 mm in diameter. Varied pipe materials have been used including mild steel cement lined (MSCL) and glass reinforced plastic (GRP) for pipe diameters greater than 450 mm, modified PVC for pipe diameters of 300–450 mm, and a mixture of oriented PVC and polyethylene for pipe with diameters of 300 mm and less.

Construction began in September 2008, with bulk earthworks commencing at GWTP followed by construction of the trunk main pipeline on Adelaide Airport land and ring main pipeline in the Park Lands.

At the time of writing, all 23 km of the ring main pipeline around the Park Lands had been installed and more than 90 per cent of the trunk main between Glenelg and the Park Lands has been completed.

The project is on schedule and construction is anticipated to be completed by end of 2009. Following commissioning and testing, recycled water will be available for use in the Park Lands by mid-2010.

Minimising impacts

The pipeline alignment was designed to minimise and, where possible, avoid public and stakeholder impacts. The project was staged through extensive stakeholder engagement and event identification to avoid significant impacts and conflict with the community and other stakeholders.

Major roads and rail intersections were crossed using tunnelling and directional drilling techniques so that key arterial transport routes were not affected by construction works.

A key engineering challenge was the open cut crossing of the River Torrens. This construction method was chosen to minimise potential impacts on the river and surrounding environment and some existing sewer services.

The volume of underground services located within the pipeline corridor presented an ongoing challenge to designers, project managers and construction crews. Indeed, the high number of underground services in a number of locations required tunnelling instead of open trenching. Other service crossings required night works.

Related to the ongoing challenge of underground services was the need for relatively deep open trenching and tunnelling works. The project delivered SA Water’s deepest pipeline asset at 12 m under the Keswick rail line. High density polyethylene pipe fabrications have been used where complex and deep pipe work assemblies required rapid and robust installations.

Park Lands significance

The environmental and heritage value of the Park Lands presented significant challenges for the Alliance in designing the pipeline alignment, installing the pipelines and managing traffic and construction.

Significant trees and their root zones– particularly within the Adelaide Park Lands – resulted in further obstacles to construction crews. These were overcome through close liaison between the designers, construction managers and Adelaide City Council staff.

The cultural heritage significance of the Park Lands to the local Kaurna Aboriginal people required specific project management solutions. Early liaison with the Kaurna Heritage Board identified key sites of interest within the project study area and a comprehensive construction monitoring program was developed and agreed with the board and implemented using local Kaurna people.