Three years after an open coal fire blazed for six weeks at the Hazelwood coal mine and power station, the LaTrobe Valley operator has made headlines again.
When the owners announced the plant’s closure in November 2016, they estimated that decommissioning, site remediation and mine rehabilitation costs wouldn’t exceed $73 million. Now, they’re saying it will cost over half a billion dollars more than first thought – bringing the total cost estimate to $743 million.
Hazelwood is the first Australian mine of its type and size to be rehabilitated, which presents a unique rehabilitation challenge for the community. A project of this scope requires expert services and an environmentally-sound and comprehensive rehabilitation plan to allow for a safe and sustainable site after closure.
Restoring the environment to its natural state
Mining is a temporary land use and all mines are expected to close at some point. Although Australia has over 50,000 abandoned mines with no clear ownership (a legacy from historical operators before current mining practices), modern mining projects have a legal obligation to ensure safe, stable and sustainable mine site rehabilitation.
During a mining project, physical and chemical processes can degrade land and waterways through erosion, loss of biodiversity, contamination of soil, groundwater and surface water, and disturbance of ecosystems and habitats.
Mine site rehabilitation is the process of repairing the damage done by mining activity. It aims to return disturbed lands and waterways to an acceptable standard by restoring ecosystem functionality and land productivity. Although the land is unlikely to return to its original state, the goal is to establish a safe and sustainable environment in a timely manner.
Degraded sites can be rehabilitated to a variety of land uses including agriculture, native ecosystems, forestry, heritage sites or, in the case of the Hazelwood mine, a pit lake.
Mine site rehabilitation and revegetation
Before mining even begins, operators must work with the government and community to determine the post-mining use of the land and develop a site rehabilitation plan which can be put in motion while the mine is still in operation.
Mine site rehabilitation is a comprehensive process that involves flattening or recontouring the steep sides of the mine, covering exposed coal and revegetating the damaged area with trees and grasses.
Techniques like hydroseeding and hydromulching are typically used to rehabilitate mine sites to maximise erosion control and establish long term native vegetation or pasture species in even the toughest conditions. Selecting a solution that is environmentally-friendly and proven to revegetate and regeneration natural ecosystems is crucial for successful site rehabilitation.
Failure to revegetate and rehabilitate
The consequences of failing to revegetate and rehabilitate a mine site are significant and far-reaching. Derelict mines, and the degraded and contaminated land they occupy, present serious risks of ongoing pollution, and severe health and safety concerns for local communities and wildlife.
Abandoned sites or sites without a proper rehabilitation plan are also potential fire hazards and susceptible to surface collapse. In 2014, the Hazelwood Mine Fire Inquiry found that mine site rehabilitation is the most effective way to prevent coal mines from catching fire or caving in.
And the consequences of site rehabilitation failure don’t stop there. Mine operator’s that decline to properly close and rehabilitate mining land can be fined by the Environment Protection Authority (EPA) and forced to surrender both their mining license and rehabilitation security bond to the state government, which can be in the tens of millions of dollars.
Mine site rehabilitation is essential for environmental sustainability, heritage protection and community safety. Operators have a responsibility and legal obligation to ensure that land disturbed by mining activities is returned to a sustainable post-mining land use, with serious consequences for those who don’t do it right.