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Preparing for Progressive Mine Rehabilitation

Sign-off in Queensland

P. Erskine, A. Fletcher and P. Swart

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• Quick history of Qld Glencore Coal operations

• Assessment of existing site rehabilitation data

• Land use options

• Standardising monitoring approach

• Conclusions

Outline

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• Compile site specific rehabilitation goals, objectives and

indicators/criteria from EAs and Rehab Plans

• Assemble/analyse historic rehabilitation monitoring methods and

results

• Acquire remotely-sensed imagery of sites

• Interpret remotely-sensed imagery and link with field

observations and data

Assessing existing site data

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Historic aerial photography

2001– internally draining landforms

2011 – maturerehabilitation

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Slopes and erosion

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Provide flexibility for sites to determine post mine land use targets

1. Land use option (LUO) classes: native vegetation, grazing,

forestry, cropping, infrastructure, recreational.

2. Indicators: What are key features related to effective function of

these landscapes?

3. Rehab hierarchy: Undisturbed to Un-rehabilitated (six levels)

4. What are the criteria for community/ecosystem quality

hierarchy?

Apply Qld rehabilitation guidelines

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Monitoring manual

• Based on the objectives for rehabilitation at Glencore Coal -

native vegetation or grazing pastures suitable for cattle

• Change from monitoring conducted in the past

• Consistent methods across sites – remote sensing then ground

survey

• Guided by land use maps and criteria developed for each site

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Targeted soil sampling - persistent bare ground

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• Soils survey conducted in areas identified by aerial photo

analysis to have persistent bare ground.

• Soil surface samples - analysed for :

– pH, EC, chloride and sulphate (SO4);

– Cation Exchange Capacity (CEC) and Exchangeable Sodium

Percent (ESP);

– particle size analysis and dispersion test;

Targeted soil samples

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Consistent transect sampling intensity - 1:15000 scale

• 1 plot per 9ha, assessed with 500m2 transects

• Cross slope (50m x 10m)

• Random start locations within claimed rehab polygons with

dispersion element

• Entire polygon is available to be sampled

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Oaky Creek Example

• 137 plots

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Plot density at Oaky Creek

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Removing areas that will be reworked

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On Ground Monitoring

• Biodiversity, erosion, soil parameters

• 1, 2, 5 and 10 year old rehab, areas older than 5 years that

are bare

• Establishment, maturation, cover and productivity, substrate

physical and chemical properties

• Compare to reference sites

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Criteria at Glencore Coal

Rehabilitation Status Criteria

Rework Have extensive areas of slopes greater than recommended for site LUO

(eg. 15% for grazing areas) and/or

Bare areas >0.1ha

Maintenance Erosion scores >3,

Have some areas of slopes >15%,

Do not meet tree density or soil chemistry (particularly EC, ESP) criteria

Monitor Meet critical criteria (soil chemistry, erosion and cover)

Have bare areas but are ecologically young

Acceptable Met all criteria

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Conclusions

• Consistent approach between sites

• Apply spatial data and GIS tools

• Adequate replication and target soil problem areas

• Understand rehab status across the business