The Islington Workshops Remediation Project arose in response to concerns of nearby residents that the rail yard site contained large quantities of friable asbestos, known to be a cancer-causing agent. Cleanup of the highly contaminated site was championed by the Port Adelaide Enfield Council and trade unions on behalf of those residents and as a tribute to those who had died or were suffering asbestos exposure diseases as a result of working at the yards. In addition to asbestos, the site contained heavy metals, hydrocarbons and other materials that exceeded safe levels for residential and industrial use, including foundry wastes (sand and slag), electroplating wastes, waste oils, miscellaneous drummed materials, scrap metal and demolition rubble, solvents, hydrocarbons and chromium (Cr6) contaminated groundwater (Figure 1).

Figure 1: Containerisation of friable asbestos hot spots

A Project with Unprecedented Challenges

Over a 5-year period from inception of the project, PB has undertaken all of the site assessment, scope development, site use planning, engineering development, environmental controls, and project management services for this complex high-risk remediation project. Our efforts have included extensive community consultation support, a vital element of the project.

This project had no precedents. There was no known process to safely relocate asbestos contaminated fill in an open air environment when our contract commenced, especially one so close to residential properties, and no concepts for land use. The brief required us to achieve six aims:

• Undertake a comprehensive understanding of site problems.
• Develop a scope that resolved all issues.
• Optimise final use of the land.
• Provide a cost effective solution and a timely procurement method.
• Provide accurate costings and timelines.
• Oversee implementation of the works.

This project involved safely relocating 120,000 m³ (470,000 cubic yards) of asbestos contaminated fill in complex and challenging circumstances. Any release of dust would have stalled or stopped the works indefinitely and possibly caused asbestos exposure.

The solution had to be implemented without risk to residents, yet achieve cost effective outcomes. Major contamination remediation projects are notorious for running over budget, typically by a factor of up to 2, and before this project no significant remediation project had come under budget in South Australia. We put our land use, engineering and management skills to the task and have achieved excellent outcomes at all stages of the project, including those described below.

Figure 2: Respiratory cap under construction

Sound Engineering Practices and Principles

Thorough analysis of risks at the outset of the project and at each stage of the project development highlighted the need to obtain an extremely thorough understanding of site conditions prior to the commencement of earthwork. Intensive investigations across the 15-hectare (37-acre) site revealed nearly all unknowns, allowing optimal solutions to be developed for all contamination issues using sound engineering practices and principles. The solutions we developed were practical and simple, such as:

• Retaining nearly all contaminated materials on site in an engineered repository capped with HDPE, geotextile, clay and topsoil layers (Figure 2)
• Constructing the repository above ground, (i.e., as a landscaped mound) to minimise interaction with shallow groundwater beneath the site
• Using rock retaining walls around a portion of the repository perimeter to maximise the repository capacity and achieve an aesthetically pleasing landscape
• Siting the repository such that it provides a noise attenuation buffer between residential properties and ongoing industrial activities on the Islington site
• Developing on site stormwater facilities to maintain all stormwater on site with controlled discharge to the underlying groundwater via soakage wells
• Developing stringent on site controls to avoid releasing of contaminated dusts during construction.
• Implementing a pumping, treatment and re-injection system to manage chromium and solvent contaminated groundwater.

Stringent Construction Controls

Asbestos contamination affected every aspect of the project, requiring an alternative approach to construction. Our team developed a new style of specification specifically for this project that seamlessly integrated engineering, environmental controls and risk management practices into one process. This specification enabled all project objectives to be achieved, including the requirement for zero release of asbestos fibres during construction.

The specification set out detailed requirements for site controls and required that the contractor trial and prove all proposed earthmoving processes on site to our satisfaction prior to implementing them full scale. Site controls and monitoring systems were developed to ensure real time management of site issues and avoid any potential delays. Procedures were established to track and characterise every bucket load of material during excavation, stockpiling and placement. In addition, defined triggers were set, such as wind operating constraints and soil moisture considerations.

Contribution to Sustainable Development

Recycled materials were used for construction where possible, to minimise the demand for natural resources. Examples include the use of crushed concrete for construction of haul roads, mulching of trees removed from the site for use in landscaping, and the use of spoil from a neighbouring site as backfill and capping material. Artificial topsoil suitable for the chosen planting species was created by adding gypsum and nutrients to the imported spoil, rather than sourcing virgin topsoil.

Retention of all stormwater on site and recharging of the shallow aquifer avoids any further loading of local stormwater systems, thus providing a sustainable solution to stormwater management.

Ongoing Environmental Management

The site management plan we prepared requires only minor long-term management and maintenance, and will be controlled by the Council on behalf of the land owner, Transport SA. This site management plan includes regular monitoring of the integrity of the repository capping layers, stormwater systems, landscaping and site improvements. The plan also specifies detailed ongoing reporting requirements, trigger points and contingency plans in the event of any unexpected threat to the integrity of the repository.

Figure 3: Artist impression of completed public park

Benefit to the Community (and the Client)

The selected repository location and configuration achieved efficient land use, adding value to the site and the locality and providing a useful new community facility. The site configuration allowed the sale of a significant portion of the site for future industrial use, thus the client could recoup significant costs. It also minimised the relocation of contaminated material and, therefore, costs and risks.

The repository area formed a significant public park (Figure 3) in a community lacking in open space recreational areas. The creation of the park allowed the Port Adelaide Enfield Council to take an interest in the site and to become the site caretaker for the long term in accordance with an agreed management plan.

The project achieved economic efficiencies for such a high risk endeavour by minimising the demand on the public purse as well. Our economic study calculated a net economic benefit to the state through health advantages and added value to the site and adjacent areas.

Project Receives Recognition

The project won the Year 2000 Australian Institute of Project Management, South Australian Project of the Year Award and was runner up at the national awards, receiving a high commendation. The project also won the Year 2000 SA CASE Earth Award for major environmental construction works and the Year 2001 Institution of Engineers Environmental Excellence Award for South Australia.