Project title: Karara Minesite Rehabilitation Research Project
Dates: 2014 - 2019
Funding: Karara Mining Limited
Location: Mt Karara, 70 km E of Morawa, approximately 400 km NE of Perth
- characterisation of rehabilitation substrates
- identification and classification of suitable plant communities
- understanding patterns of water movement in soils
- returning native species to reconstructed soils
- determining rehabilitation trajectory
Tailings are a fine-particulate material consisting mainly of silica that is produced in large quantities during the processing of magnetite ore. Traditionally, tailings are managed in a wet, slurry-like state, stored in large tailings dams. However, in semi-arid environments water can be a scarce and limiting factor for remote operations.
In the dry Midwest of Western Australia, iron ore miners Karara Mining Limited (KML) have adopted a novel method of tailings production, with a dewatered dry stack tailings storage facility being operated at their Mt Karara minesite east of Geraldton. This project focuses on the rehabilitation of the tailings storage facility at Karara, with specific focus on four key research areas:
- Characterisation of the key physical, chemical, hydrological, and biological attributes of dry stack tailings;
- Identification of suitable plant communities for the rehabilitation environment;
- Understanding the patterns of water distribution both in natural soils and in the tailings material;
- Determining best-practice approaches to monitoring the trajectory of rehabilitation.
This research program focuses on the application of best-practice restoration methods to a novel rehabilitation substrate, and is directed by the philosophy that the simplest way to recreate biodiverse plant communities is to create rehabilitated communities that match the environmental conditions of the site. Native plants differ in the environmental attributes that limit their natural occurrence, the traits that define this interaction with the environment, and their reproductive and dispersive capacity. Understanding these differences, as well as the hydrological, biological, and physic-chemical characteristics of the rehabilitation environment, provides a way to optimise the selection of plant species to develop persistent, self-sustaining communities.
The physical, chemical, and particularly hydrological properties of waste dumps differ markedly from undisturbed natural substrates, and may be challenging for plant growth and native plant community establishment. In arid and semi-arid environments, water availability is a key factor limiting plant growth and survival. Examining the water status and patterns of water use of plants in intact systems can identify the periods, seasons, and conditions under which plants function, and those under which they become stressed. Reconstructing substrates with hydrologically suitable conditions is an essential step in ensuring successful rehabilitation of species-rich local plant communities.
Monitoring the development of natural communities, assessing their ability to become self-sustaining, and determining trajectory towards rehabilitation success is difficult given the time-frame required to demonstrate sustainability in plant communities. A key aspect of this study involves the development and optimisation of rehabilitation monitoring techniques that provide a snap-shot of rehabilitation trajectory, such as plant-level indicators of performance, reproductive and recruitment capacity, and resilience to seasonality and climatic change.
Dr Adam Cross, Dmitri Ivanov, Dr Jason Stevens, Prof Kingsley Dixon
University of Western Australia