ACARP ACARP ACARP ACARP
Open Cut

Risk Management Strategies for the Surrender of Open Cut Dragline Spoil Pile Areas

Open Cut » Environment

Published: June 01Project Number: C8039

Get ReportAuthor: David Williams | University of Queensland

Forestry and native habitat are more sustainable post-mining land uses for central Queensland mines than grazing or cropping.  The emerging government vision is driven by the principles of ecological sustainable development and is enshrined in the Environmental Protection Act, which protects and enhances environmental values, including air, downstream water quality and land management. Native habitat or bushland is now the preferred post-mining land use for about half the Bowen Basin open cut coal mines. It is recognised that unmined landforms are irregular, while mined landforms tend to be regular (engineered) and that post-mining landform design should aim to blend the mined landform with the surrounding unmined landform. The primary aim of this project was to develop a multi-disciplinary risk management tool to select rehabilitation strategies for the surrender of Bowen Basin open cut coal mine spoil areas, using the most cost-effective and environmentally acceptable approaches. The methodology comprised:

  • Literature review and commentary, based on available published information, carried out during the first half of the project.
  • Collection of data and observations on spoil rehabilitation from Bowen Basin open cut coal mines.
  • Collection of the views of stakeholders on spoil rehabilitation and future land use.
  • Development of a risk assessment and cost-effectiveness tool for spoil rehabilitation and future land use, taking into account the available information and views of stakeholders.
  • Application and demonstration of the risk assessment and cost-effectiveness tool through focused workshops.  
  • Through ACARP, widely disseminate the results of the research throughout the Bowen Basin.

Researchers collected available data on the key parameters, including topography, climate, spoil type and distribution, water quality, the performance of unrehabilitated spoil piles, and the design, costs and performance of a range of approaches to spoil pile rehabilitation and revegetation. For unrehabilitated spoil piles, observations on natural reshaping and revegetation, the stability of steep slopes in durable spoil, the instability of erodable spoil, and armouring were collected. For rehabilitated spoil, researchers collected observations on erosion, revegetation success, and the potential for land use.

Findings

The key causes of land use failure and, by inference a failure to achieve lease surrender, are landform instability, surface water impact, groundwater impact, vegetation failure, animal failure, poor perception and negative socio-economic impact.

Some of the key points derived from the literature review and commentary are:

  • Historically, the overriding aim of spoil rehabilitation was a return to productive land use, with a focus on grazing, through future grazing on spoil is now generally seen as impractical in the Bowen Basin.
  • Aesthetics must be considered in designing spoil rehabilitation, along with safety, stability and land use.
  • Most Bowen Basin spoil materials are geotechnically stable at a slope angle of 33 percent or steeper and elevated spoil materials on stable foundations will be stable at their angle of repose.
  • The Queensland Department of Minerals and Energy target erosion rate for rehabilitated spoil of 12 to 40t/ha/a is typically 30-fold higher than natural erosion rates and river sediment yields, typically four-fold higher than erosion rates from agricultural land, but typically 10-fold lower than erosion rates from construction sites.
  • Erosion loss increases with slope angle and slope length, and decreases with vegetative, litter and coarse particle cover, and with profile concavity.
  • The average cost of conventional rehabilitation in the Bowen Basin is about $19,000/ha (ranging from $3,000 to $35,000).
  • The remaining potential spoil rehabilitation liability is around $825 million of a $1 billion liability.
  • The major shortcomings are entrenched perspectives, inadequate definition of rehabilitation success criteria, inadequate understanding and knowledge of spoil hydrology, the lack of field data on erosion from steep spoil slopes, paucity of acid mine drainage and salinity data, lack of proven spoil rehabilitation strategies, and paucity of data on the hazards and impacts of alternative land use surrounding mine sites.

Where To From Here

While the project is directed specifically at spoil areas in the Bowen Basin coal fields, the results may have application to other disturbed areas such as final voids, tailings dams and coarse reject dumps, and to other open cut coal mining regions.

Underground

Health and safety, productivity and environment initiatives.

Recently Completed Projects

C27039True Triaxial Strength Of Coal Measure Rocks And Its Impact On Roadway Stability And Coal Burst Assessment

Rocks in the ground are subject to a range of stresses. The stresses...

C3063Underground Vehicle Design Standards And Statutory Implications

The Australian underground diesel vehicle fleet has evolved since di...

C3064Conveyor Belting And Lagging Shear Characteristics - Drive Drum Slip

The primary aim of this project was to investigate the relationsh...

Underground

Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C29021Assessing The Impact Of Consecutive Night Shifts On Night-Time Alertness, Daytime Sleep And Timing Of The Circadian System

In the Australian coal mining industry, most guidelines for managing...

C33037Quantifying Recharge To Groundwater Systems In The NSW Coalfields (Sydney, Gunnedah And Gloucester Basins)

The purpose of this project was to estimate the rate of diffuse rec...

C26029Geological Controls On Fluorine And Phosphorus In Bowen Basin Coals

Increasing global restrictions on fluorine in product coal prompted ...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27064Dry Beneficiation Using FGX And X-Ray Sorters

Conventional dry processing methods engage a single beneficiation de...

C26010Multi-Sloped Screening Efficiency With Changing Strokes, Frequencies, Feed Solids And Feed Rates-Pilot Plant Study

Optimising multi-sloped screens is often described as an art and the...

C28059Impact Of Water Quality In Coal Handling And Preparations Plants

The objective of this project was to deliver a concise reference do...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C23052Novel Stone Dust Looping Process For Ventilation Air Methane Abatement

This multi‐phase project is concerned with the mitigation of m...

C27054Optimisation Of A Thermal Flow Reversal Reactor For Ventilation Air Methane Mitigation

Ventilation air methane (VAM) generally accounts for 50-85% of the t...

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL) - Phase 2 Demonstration In A Packed Bed Reactor

An alternative approach to high temperature oxidation of ventilation...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community

NERDDC

National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook

NERDDC