Open Cut

Sustainability Indicators for Coal Mine Rehabilitation

Open Cut » Environment

Published: April 01Project Number: C7006

Get ReportAuthor: Chris Carroll, Andrew Tucker, L Merton, P Burger, L Pink | Department of Natural Resources and Mines

A seminal study has provided the mining industry, regulators and the community with a true picture of what is needed to produce successful rehabilitation on Queensland mine sites.  Replacing inappropriate agricultural research methods with techniques relevant to mining , highly regarded environmental scientists from the Queensland Department of Natural Resources and Mines monitored the impact of open cut mine rehabilitation on erosion and water quality under natural rainfall conditions. The six-year study gave scientists the opportunity to gather data over the range of climatic conditions that occur in central Queensland, from crippling drought to heavy wet seasons. Using mine scale plots and catchments, they were able to generate meaningful data that could be used on site to produce effective rehabilitation programs.

The outstanding final report is devoid of the usual scientific jargon and is presented in an easy-to-use format. The key points are well summarised. High-tech photographic morphing clearly illustrates changes in rehabilitation over the six-year period and why erosion occurred. The report is a compelling communication tool.

Prior to this research, there was little information on erosion rates from open cut coal mine rehabilitation in Australia, particularly under natural rainfall. Most erosion research had been conducted on agricultural soils and land use, and on lower slope gradients.

Project Objectives

The project's objectives were to:

  • Monitor the long-term impact of open cut mine rehabilitation on erosion and water quality under natural rainfall conditions
  • Evaluate physical and biophysical indicators for sustainable rehabilitation
  • Use the monitoring sites as an educational resource and promote outcomes from the study to the industry and the wider community.

In particular, this research assessed runoff, erosion and water quality from rehabilitated land at Curragh, Goonyella Riverside and Oaky Creek mines at two scales - plot (0.01ha) and catchment (0.4ha to 0.9ha) - and three slope gradients - 10 percent, 20 percent and 30 percent. Pasture and tree vegetation treatments were imposed on topsoil and spoil materials and a number of topsoil and spoil plots at each site were left bare to compare with the vegetative treatments.


Pasture cover is the preferred indicator of rehabilitation sustainability and stability, and topsoil is the more suitable material for vegetation establishment on rehabilitated land. The use of topsoil and pasture cover produced the least runoff, sediment and soluble salt transport. A minimum 50 percent ground cover should be attained for erosion control.

Pasture establishment on spoil was poor at all mine sites, especially where the spoil was hard setting and dispersive. Annual erosion rates from spoil remained unacceptably high throughout the study. Where spoil was high in in situ soluble salts, the electrical conductivity levels from the resulting runoff were also high.

By the final year of the study, soluble salt levels in runoff from all topsoil pastured slopes had reduced to less than 200mS/cm, which is comparable to the water quality found in local creeks.

Runoff and erosion rates from the rehabilitated contoured catchments progressively declined during the study, with a corresponding improvement in water quality.

Research outcomes were shared with mine environmental staff, government agencies, landholders and consultants during a series of Landcare and Central Queensland Mine Rehabilitation Group field days.

The key findings of this research are:

  • Rainfall is the major limiting factor associated with successful rehabilitation. It is critical that pasture cover is established rapidly in order to maximise rainfall infiltration.
  • A rehabilitated landscape is at greatest risk of erosion before grass cover is established. The window-of-erosion risk occurs before vegetative growth reaches 50 percent ground cover.
  • Pasture establishment to 50 percent cover should be a minimum target indicator for coal mine rehabilitation. Further increases in pasture cover (greater than 80 percent) and biomass are required to reduce erosion rates on 30 percent slopes to negligible levels.
  • Topsoil erosion rates declined between slopes once a dense sward of grass cover established (greater than 80 percent cover).
  • Vegetative cover reduces the risk of salt movement on-site and off-site through runoff.
  • The development of a hard dispersive crust on the spoil material reduced infiltration, produced very poor pasture and tree establishment and resulted in unacceptably high runoff and erosion.
  • Surface ripping of slopes greater than 20 percent should be used to improve infiltration and reduce runoff and erosion losses.
  • Supplementary irrigation should be used to assist rapid pasture establishment during periods of low rainfall.


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...


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


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