Open Cut » Environment
The aim of this project is to add a further technical component and a social approach to determining performance standards for diversions at relinquishment. The objectives of this project are to:
· Identify acceptable condition trajectories for diversions that would allow for future diversion relinquishment;
· Define performance standards to measure progress or otherwise along the accepted condition trajectories;
· Develop a framework for stakeholder and scientific assessment of diversion condition as part of the relinquishment process;
· Identify refinements to the current diversion monitoring program to reflect the performance standards.
Constructed watercourse diversions are a common feature of coal mine sites across Australia. In the Bowen Basin coal fields in central Queensland there are over 90 watercourses that have been modified in the form of diversions of various scales to access coal reserves (Alluvium 2014). For this report, a constructed watercourse diversion (also referred to as a diversion) is defined as a constructed channel that diverts or changes the course of water flow from a natural watercourse in association with mining activity.
Watercourse diversions in Queensland have been the subject of several ACARP research projects over the past 15 years. Through this research the premise that diversions need to function as self-sustaining and integrated components of the wider stream network has been acknowledged and accepted by the mining industry and state government (DNRM 2014). The development and refinement of diversion design criteria and guidelines has underpinned the self-sustaining goal which has also been supplemented through the development of a monitoring program tailored for diversions to track the condition from construction to relinquishment.
A permanent watercourse diversion should be designed and operated to ensure that it is stable, self-sustaining and does not impact on the adjoining upstream and downstream reaches of the existing watercourse. A self-sustaining diversion functions without features or characteristics that rely on ongoing maintenance or that impose a financial or other burden on the proponent, government or the community. DNRM 2014
With prevailing market conditions for many commodities and resource depletion, some mines are presently undertaking closure planning to a more detailed level than contemplated before. Consequently, the rehabilitation requirements for diversions at coal mines in the Bowen Basin may be receiving more attention compared to the 2000's. For mines with diversions this has raised the question: 'When and how can a diversion be relinquished?' While general relinquishment requirements for a mine lease are outlined in environmental authorities and generally for diversions in water licence conditions, the requirements are also to subject to negotiation with the Queensland government regulators. This report refers to licenced watercourse diversions, however there are many if not more unlicenced watercourse (that do not meet the Queensland Water Act definition of a watercourse) diversions at mine sites to which the findings of this and related ACARP projects can be applied. In recent times, the Queensland Government has offered mine lease holders the opportunity to obtain approval for a diversion through the sites Environmental Authority (EA), the outcomes of this project apply equally to all diversions regardless of approval mechanism as well as those that have not been subject to any approval mechanism.
While the earlier ACARP projects for diversions have provided the design tools and framework for diversions to be constructed based on the forms and processes of natural streams, the issues of when and how a diversion can be relinquished have not been explicitly addressed. Given that the Department of Natural Resources and Mines (DNRM) state that a diversion must not impose a financial or other burden on the proponent, government or community this indicates that stakeholders must also have input to a decision about whether a diversion can be relinquished. This raises the question: what are stakeholders' expectations of diversions at the point of relinquishment, and is it similar to the expectations outlined in research and accepted by the industry? Furthermore, the role of stakeholders in diversion relinquishment assessment is unclear and no consultation has been undertaken to date regarding stakeholder expectations for diversions at relinquishment and/or mine closure.
This research project explores and defines the role of stakeholders in the diversion relinquishment process. Furthermore this project provides a framework in which monitoring data and stakeholder assessment are combined to provide evidence that a diversion is suitable for relinquishment. To provide this evidence, this research project has also focused on the development of trajectories against which diversion performance can be assessed and tracked through time.
Clear performance standards linked to diversion licence relinquishment will enable the mining industry, government and stakeholders to track diversion condition and understand the measures required to continue on an acceptable trajectory towards licence relinquishment.