Site management

The Department for Energy and Mining has retained management responsibility of the site for the government, and maintains a continuing watch on the site with radiological advice and assistance from the Environment Protection Authority.

Radiation and environment management plan

In accordance with the condition of licence, radiation and environment management plans (REMPs) must be prepared and approved by the EPA and implemented for the sites. These plans were developed in 2016.

Groundwater sampling and monitoring

Groundwater sampling and monitoring is used to determine what mechanisms and processes are occurring with respect to hydrogeological conditions at the site. This commenced in 2006 and is an ongoing part of REMP commitments (bi-annual, monitoring well, level dipping and 5 yearly groundwater sampling).

Site assessment

The remedial actions for Port Pirie are based on a series of phases to identify site history, site characterisation and risk to determine the optimal strategy for controlling the identified long term risks.

Phase 1

A preliminary investigation of the site, completed in 2004.

Phase 2

A more detailed site characterisation which included:

  • Geotechnical investigation - preliminary assessment of the structural integrity of the former Port Pirie Treatment Plant tailings impoundments. Completed 2005.
  • Surface alpha contamination survey - radiological testing of buildings prior to demolition. Completed 2005.
  • Waste qualification/site survey- to quantify all existing wastes, covers etc. and locate all services, boundaries etc. Completed 2005.
  • Hydrogeological investigation - to provide sufficient data and information to achieve a greater understanding of the local hydrology. Completed 2006.
  • Resource economic potential evaluation - to determine what economic value and potential remain (if any) in the residue products onsite, namely the tailings resulting from the original extraction of uranium from the Radium Hill mine ore. Completed 2006, reviewed internally in 2018.
    • ANSTO June 2006: A report to PIRSA on Assessment of the economic potential of rare earth elements within the uranium residues at the former Port Pirie rare earth treatment plant.

Extensive consultation was undertaken by the government in 2005 to 2007 with key local stakeholders including the Port Pirie Regional Council, the Regional Development Board and Zinifex (now Nyrstar) to provide important input into the risk assessment.

The other major undertaking in 2006 was the demolition of all infrastructures at the Port Pirie rare earth treatment plant site. The six original uranium tailings dams and the rare earth extraction dams remain on the site. These cover approximately 26 hectares containing some 200,000 tonnes of tailings.

Phase 3

Covers the risk assessment and control selection for the site.

Upon completion of phase 3 sufficient information should be available to enable an effective and informed decision to be made on the future management of the site (Phase 4).

Phase 3a: Risk assessment and control scoping has been completed.

Phase 3a - Risk assessment and control scoping

Phase 3a has been completed.

Risk assessment considers potential human health and ecological exposures and relevant radiological and chemical toxicities which might occur in a given environmental situation. An estimate using realistic but worst case assumptions of contact with the contaminants is made.

The South Australian government engaged ENSR (now part of AECOM Australia) to perform a Contaminated Site Risk Assessment and Remediation Control Scoping Study as part of the Radium Hill Uranium Mine remediation project. ENSR is a leading global environmental consultancy with over 25 years’ experience in environmental risk assessment.

Between 2003 and 2010 the South Australian mine regulator engaged AECOM consultants to undertake a detailed site characterisation, including human health and environmental risk assessments and options for ongoing management of the risks.

Background

From 1968 to 1972 a private company, Rare Earth Corporation (REC), took possession of the site and processed monazite to produce rare earth concentrates. During this time an additional tailings dam was constructed.

From approximately 1979 until 1986 the site was used for the recovery of lead from batteries and copper from electric cables by a local contractor. In addition a portion of the tailings dam was used during the 1980s as a licenced asbestos waste depot. Nyrstar had also stored process materials in one of the buildings on site. During this period the tailings dam area was fenced with six-foot cyclone mesh and warning signs added. Slag from the adjacent smelter was also placed over a number of areas around the uranium and REC tailings dams.

In the mid to late 1980s, the South Australian government commenced a program of rehabilitation of the tailings impoundment by covering the area with approximately 2 metres of granular slag supplied by the adjacent Nyrstar Smelter (then BHAS); this was overlain by 150 to 300 mm of topsoil to encourage vegetation growth.

In 2004 the government demolished the remaining buildings and plant at the site. Some demolition waste was buried. A quantity of structural steel and other material with radioactive contamination remains on site.

The project

In 2009, a risk assessment and control scoping study was conducted to estimate human and ecological risks associated with radiological and non-radiological contaminants within the terrestrial environment, and develop plans for managing the risks associated with the two sites.

Understanding the risks will enable potential options to be identified for the future and responsible decisions to be made regarding remedial action for Port Pirie.

Radiation and environmental risks

The human health radiological risk assessment studies found that under the existing scenarios (on-site trespasser, on-site recreational user, Nyrstar worker, maintenance/monitoring personnel, industrial worker, intrusive maintenance worker, and off-site recreational user) it is unlikely radiation doses will exceed dose limits set by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Exposure limits were based on the current exposure limit for members of the public of 1 millisievert (mSv) in a year.

International standards (from the International Atomic Energy Agency) provide a dose criterion of 1 mSv for exempting requirements for further action, commensurate with typical doses due to natural background levels of radiation. Thus, from a purely radiological perspective, no further remediation or controls are required.

More information can be found in the EPA fact sheet, Naturally occurring radioactive material (NORM).

Whilst short to medium term risks identified in the scoping study have been addressed in the REMPs, further studies will be required to determine the optimal strategy for controlling the identified long term risks. The short to medium term risks are focused on the human health chemical (non-radiological) risks, human health radiological risks, ecological risk assessment and technical risk (for example geotechnical, hydrological etc.).

Port Pirie risk issues and uncertainties identified are related to the potential for contaminants to mobilise due to structural failure of the dams, erosion or seepage. The potential for reduced dam stability would be exacerbated by climate change.

Risk assessment and control scoping studies reports

The AECOM risk assessment and control scoping studies were key steps towards the development of long term management plans for this site.

Phase 3b - control selection

Control selection will involve further studies to determine the optimal strategy for controlling the identified long term risks.

Phase 3b is yet to be completed.

Phase 4

The final phase will see the development and implementation of an appropriate long-term management plan for the site. As part of this strategy there is a need to inform and consult with various stakeholders to implement an outcome for the present and ongoing management of the site.

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