At the Institute of Quarrying Hong Kong Branch’s annual conference in November 2016, I presented a paper – Green quarrying – An Australian perspective – that highlighted examples of green quarrying practices across Australia.
Every state and territory has legislation for approving and regulating quarries while the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) is the Australian Government’s benchmark legislation. Many of the states incorporate EPBC Act requirements into their approvals. For example, the Native Vegetation Framework in each jurisdiction requires appropriate offsets for the clearing of vegetation. Licences are required for groundwater and water discharge. Cultural heritage sites must be protected through a heritage management plan. Planning approval enables community input via local council or state process.
The legislative framework provides drivers for our industry to improve its green credentials but we also need to achieve best practice.
The Canadian Government has partnered with industry and other stakeholders on the Green Mining Initiative. It accounts for everything on a mine site through four interconnected research and innovation pillars:
1. Footprint reduction. This aims to curb physical disturbance, minimise community and environmental impacts and achieve reductions in waste generation and energy usage. Progressive rehabilitation is a good way to ensure that the physical footprint is minimised through the operational phase.
2. Ecosystem risk management. Baseline studies and environmental impact assessments are part of the approval process. An environmental management plan with controls that ensures compliance with standards would ameliorate environmental risks. Regular monitoring of those controls and sharing of results with key stakeholders is best practice and will demonstrate our green credentials.
3. Waste management. Many quarries are into recycling. Most of the concrete from building demolition is crushed to produce quarry products. Some authorities have amended their standards to encourage recycling.
For the sand and gravel waste stream, an alternative is to use a filter or belt press to extract water and place the mud with the overburden and progressive rehabilitation. Concrete sand manufacture from excess dust – generated from crushing – has supplemented depleted sand reserves in the eastern states.
A power-generating downhill conveyor project at Hanson’s Hobart quarry is a great example of green quarrying. It has reduced the quarry’s electricity consumption by 48 per cent, saved an estimated 170,000 litres of fuel per year, and improved dust and noise emissions.
4. Mine closure and rehabilitation. Historically, our industry has left legacy mines and quarries with very little rehabilitation. Acid draining issues in mines have left governments with massive liabilities.
Regulators now require rehabilitation plans to be incorporated in the approvals up front, with the lodgement of rehabilitation bonds for those companies that default on the duties to rehabilitate the sites. Companies are required to monitor how rehabilitation is progressing and demonstrate they have met the standards of the rehabilitation plans.
We have many examples of best practice rehabilitation in the industry. In Hong Kong, the community understands that quarry sites provide precious land for residential development. However, the expectation is that quarry operations must minimise the impacts on their neighbours.