Situation: Five hectares of land at Pickertaramoor on Melville Island was the planned site for the new Tiwi College campus. The site had housed a tree plantation depot and a copper chrome arsenate treatment plant.
Geo-Logix was engaged to prepare a Remedial Action Plan for the site. The levels of lead, arsenic and petroleum in the soil prohibited its use as a school, and there were asbestos-containing materials from the uncontrolled demolition of the plantation depot.
Challenges: Geo-Logix had to overcome a number of challenges to complete the project. A creative approach was needed to assess and manage the contamination of such a remote site. Additionally, the project required consultation and communication with a range of stakeholders including representatives from the Department of Education, Indigenous Affairs and the Environmental Protection Authority.
Action: Geo-Logix worked with the client and stakeholders to develop and implement an effective remediation plan. The project involved:
- Reviewing existing contamination reports and performing a gap analysis
- Undertaking additional investigations to fill the data gaps
- Developing a remediation strategy that would satisfy the Northern Territory EPA and the EPA-appointed auditor
- Preparing the Remedial Action Plan report
- Supervising, undertaking and validating the remediation to the satisfaction of the EPA and auditor
Result: Due to the remoteness of the site, Geo-Logix proposed designing and constructing a contamination-containment cell on Melville Island. To find a suitable location they undertook geological, hydrogeological, hydrological, and flora/fauna studies, and consulted with stakeholders.
Geo-Logix brought on structural engineers, Henry & Hymas, to assist with the cell design incorporating a high-density polyethylene (HDPE) liner, leachate collection system and a HDPE capping layer with flow net. The design included a re-vegetation plan to provide long-term stability, and an adjacent unlined cell for disposal of asbestos waste.
The Remedial Action Plan, delivered by Geo-Logix, included the construction details for the containment cells together with the remediation plan and validation methodology.
Incidentally, on hearing about the asbestos containment cell, the Strategic Indigenous Housing and Infrastructure Program proposed to use the cell to deposit asbestos materials from housing demolition on Melville and Bathurst Islands.
The remedial plan was successfully implemented, the school was built and the Tiwi College is building the knowledge and skills of indigenous students.