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Soils & rehabilitation FAQ

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Australian Rare Earths Ltd

Australian Rare Earths believe mining and agriculture can co-exist with mutual benefits and we’re investigating where we may be able to improve soil quality in some areas. 

The following questions and answers are explained in more detail in this Webinar:

How do you ensue the soil goes back the way it came out?

Excavations are conducted methodically, with each layer excavated, assessed and stockpiled separately. This ensures we can optimise the rehabilitation opportunities when backfilling in the correct order.

See the  Minerals Council of Australia fact sheet on 

What is the impact of the topsoil structure in terms of organic matter levels?

Topsoil and subsoils are stockpiled carefully to retain the organic matter. Our studies have shown that the carbon is, for the most part retained, but more evenly distributed throughout the top 30cm. You can see the analysis information 

What is the impact of soil structure via mixing of different soil horizon layers?

Topsoils and deeper subsoils will not be mixed or inverted during rehabilitation, the depth of topsoils will be clearly defined and then stockpiled separately during mining excavations, to ensure the best rehabilitation outcomes.

Due to the nature of the geology of the soils, there will generally be a minimum of two metres of subsoils (unprocessed overburden) between the returned processed clay and the stockpiled topsoil. Therefore 'mixing of soil horizons' is not expected to occur.

See how the topsoil and subsoil will be stock piled separately in this 

What impact does removing the rare earths have on the remaining clay?

The mineralised clay layer is very deep, 4-10m below ground, and sited on top of the limestone, it serves no purpose from an agricultural perspective, as it is too far out of the root zone.

Can amendments be added to neutralise the chemicals used?

Yes the Mining Plan will identify options to neutralise any residual chemicals, prior to returning the clay to the void.

Observations undertaken during the rehabilitation of the Bulk Sample pit showed compaction was for the most part contained to the top 50cm in areas of high traffic, such as the vehicle laydown area.

Through the rehabilitation work, compaction was rectified with specific agricultural practises and targeted selection of plants to build structure and ensure good drainage.

Learnings from the Bulk Sample pit and rehabilitation work will help inform project engineering and design to help avoid compaction where possible and incorporate appropriate rehabilitation techniques if necessary.

Careful backfilling and reprofiling of the landscape using best practice for the soil type will focus on ensuring erosion does not occur.

How will you manage rehabilitation with the variability/differences in topsoils across the landscape?

When conducting any excavations, the fundamental principles of good rehabilitation remain the same, in that it is crucial that topsoil depths are understood and retained and that soils are returned in the correct order.

AR3 are conducting ongoing studies to ensure they understand all the site specific soil profiles, so any site specific nuances can be included in the mine and rehabilitation plan.

Are you assessing soil microbiology, organic matter and particle size?

Thorough soil analysis will be undertaken prior to excavation (baseline) and repeatedly during rehabilitation works to ensure we maximise all opportunities to improve soil health.

What is the Trial Pit and how was it rehabilitated?

AR3 developed a bulk sample pit referred to locally as the ‘Trial Pit’ in 2022 to gain greater understanding of the mineralised clay to inform the mining plan.

This was a great opportunity to undertake some good rehabilitation studies of the land, whilst returning the site back to its pre-mine activity. 

The pit was excavated in April 2022 and backfilled 2 months later in June 2022. Active rehabilitation commenced the following spring, October 2022; 

For more information on the Trial Pit and Rehabilitation, 

View the Rehabilitation Progress Update here:

See below photographs showing the progressive rehabilitation of the Bulk Sample Pit.

Image 1 - April 2022
Image 2 - Sep 2022
Image 3 - Oct 2024

Example of Rehabilitation