Open Cut » Environment
Water is increasingly recognised as a material risk by mining companies, however corporate water management strategies tend to be heavily focused on access to water for production and processing and do not necessarily capture the other water related risks. Stormwater runoff generated by mine sites constitutes a core environmental risk and mine affected runoff often contains contaminants that threaten the health of the receiving environment. Key components that may pose a risk to the environment include sediment and suspended solids, which are a major cause of ecological degradation in aquatic ecosystems. In Queensland, elevated salinity is often recognised as being a key contributor to the toxicity of many mine affected waters, while pH, sulfate and metals are often associated with acid mine drainage. Stormwater management follows standard principles but must be adapted to local regulatory frameworks, which are continuously evolving. In addition, stormwater management is context specific in terms of the climate, weather, geology, contaminant of interest and environmental values of the receiving environment and therefore, needs to be adapted to the local context.
In Queensland, the Department of Environment and Science issues an environmental authority (EA) to authorise the carrying out of an environmentally relevant activity. Tthe Queensland Government commissioned the Review of the Fitzroy River Water Quality Issues report (Hart, 2008), which recommended that a catchment management plan and a coordinated catchment wide monitoring and assessment program be developed. A water quality program was initiated by DERM to address community concerns and the Study of the Cumulative Impacts on Water Quality of Mining Activities in the Fitzroy River Basin (DERM, 2009) was produced. The study recommended that standardised conditions be imposed on the quantity and quality of water discharged from mines sites in the region. These conditions were conservative and significantly reduced release opportunities for coal mine operators to discharge mine affected water into waterways.
Prolonged rainfall over the Queensland mining areas during the 2010/2011 wet season caused significant impacts to the industry when large volumes of water flooded mine sites and either restricted production or caused operations to cease entirely. In early 2011, the Queensland Premier instructed all agencies to facilitate a timely return to full production capacity. The Department of Environment and Resource Management (DERM) was called to resolve tension between environmental and economic objectives, while administering the Environmental Protection Act 1994, which aims to ensure the protection of the environment while allowing development. DERM had already started authorising the discharge of water from mines under strict conditions into flooded waterways. These circumstances led to a thorough engagement process between industry and government to draft a new regulatory framework to deal with mine-affected water.
This project aimed to:
- Provide improvement of mine site ESCPs by engaging with industry representatives and DES teams;
- Derive clear objectives for ESCPs;
- Agree on a shared understanding of what constitutes non-mine affected runoff; and
- To develop technical guidelines that will assist miners with ensuring their ESCPs comply with the model water conditions.
The final outcomes of the project include the ability to retain the option of passively releasing non-mine affected runoff to the environment; reduced expenditure through better integration of erosion control requirements in short and medium term mine planning and scheduling; more efficient pre wet season preparedness; and a stronger license to operate through improved management of the potential impacts on surface waters of open cut mining and, to a lesser extent, underground mining.