Chasing the Waste from Coal Seam Gas methane mining in the Pilliga

By Johanna Evans

Methane gas mining waste comes in many different forms and is produced by several different processes at multiple stages of mining operations. This story focuses on what’s happening in the Pilliga Forest, NSW in August 2023.

Drilling Waste to be spread in the Pilliga Forest

Scrutiny is urgently needed of the approved Waste and Rehabilitation Management Plans for the Narrabri Gas Project. The Residual Drilling Mud (RDM) Management Protocol is part of the Rehabilitation Management Plan. Approval has been granted to Santos to spread and bury rock-based residual drilling materials containing chemicals of concern on the floor at the surface in the Pilliga Forest. Geogenic contaminants are chemicals of potential concern that can be mobilised to the surface by the action of drilling new wells.

Companies in Queensland have been disposing of drilling mud under the pretext of beneficial use for several years. Several metals are present in most drilling muds such as arsenic, barium, boron, cadmium, copper, chromium, lead, mercury, nickel, vanadium and zinc.

In NSW, the activity of burying/spreading the RDM is regulated by ‘The excavated natural material order 2014’ (ENMO) – this order does not specify any requirement to test for barium, boron, iron, manganese, vanadium, strontium, thorium and uranium. All of these metals are identified as being constituents of RDM. Chloride is also not identified by the ENMO, and it is listed by Santos’ RDM Management Protocol as not being relevant ‘because the Pilliga is not a food producing area’, yet it is internationally recognised that the chloride ion “can be defined as a contaminant in land operations, with the potential to inhibit the growth of vegetation, and it can also be considered a potential pollutant to aquifers”. Chloride is one of the main ingredients of drilling mud. No study has been conducted on the impact of adding chloride to the Pilliga soils.

Santos do not currently have approval to bury and spread coal-based drill cuttings (compositionally different to rock based cuttings) so it is important that community are aware of the need to transport this type of waste to a licensed landfill. Several have been identified in the Waste Management Plan. Some history of the RDM issue is available here. It is very likely that Santos have begun the process of applying to dispose of coal-based RDM in the forest.


The NSW EPA needs to urgently review the suitability of the ‘Excavated Natural Material Order 2014’ and associated exemption when using with coal seam gas. It seems likely that a new order and exemption that is specifically designed to deal with RDM from coal seam gas operations may be necessary due to the presence in RDM of analytes not considered by the currently applied Order.

Santos has failed to provide salt solutions

In January 2023 Tritton Resources (EPL 4501) applied to extend the Heap Leach Pad Remediation Trial using Santos’ CSG concentrated brine for acid mine drainage neutralisation by 12 months. The trial has been slow to progress, investigations began in 2019 and it must cease by 31 December 2023 with a final report to be provided to the EPA by 29 February 2024.

The issue of Santos’ toxic salts waste in NSW has captured public interest due to the lack of acceptable solutions. The Produced Salt Beneficial Reuse and Disposal Study mentions algae farming and commercial salt recovery. This study is very light on when it comes to actual operational detail with reporting on proposed solutions delayed until Phase 3. This appears to be an erosion of the much touted “strict conditions”. We look forward to seeing a study with more substance. The fact that there are no serious solutions other than landfill is of great concern to us.

The study also relays “use of the amended treated water for crop irrigation within a 25-km radius from Leewood is currently the subject of an application to the NSW Environment Protection Authority (EPA) for a Resource Recovery Order and Exemption (RROE).”

Liverpool Plains waste brought to the Pilliga

Santos have informed community near the Kahlua wells that they will be restarted in late August 2023. The NSW EPA have given Santos permission to transport the produced water waste via road to their Leewood Water Treatment Facility on the edge of the Pilliga Forest. Alternatively, the produced water may be offered to a third party as beneficial reuse subject to a successful application for a resource recovery order and exemption. Santos state in their Review of Environmental Factors that they expect to see 25m3 of Produced Water every day for the 2 years of appraisal operations. This equates to 8,900m3 per year.

Why what happens in Queensland is relevant to NSW…

Recent developments in Queensland have seen an CSG Brine Management Action Plan published by the Queensland Government and a subsequent proposal by an ASX listed company Parkway Corporate.

Parkway Corporate via a recently established subsidiary, Queensland Brine Solutions Pty Ltd (QBS) ACN: 668 367 011, claim to be developing technology to enable produced water to be turned into saleable products, thus removing the need to bury the CSG brine in salt tombs. This technology will need to be scrutinised closely to see if it is able to treat the expected industry waste salts volume of six million tonnes.

NSW has an expanding extractives industry that will be keen to benefit from technology which treats alkaline waste. How much waste can we feasibly generate before it becomes more than we can treat and have we already passed that point? The staff who currently work for Santos in NSW are mostly from Queensland and most of the contractors who come into NSW to work are from Queensland. There has also been a revolving door from the EPA to the Gas Industry and vice versa.

This Post Has One Comment

  1. Adrian Watkins Reply

    The brutal indifference to our planet by companies such as Santos is truly revolting. These companies seem to have no understanding at all of the ecological impacts on Earth of their behaviour, addicted as they are to greed. Little do they understand that in the long term, maybe even in the short term, their demise is assured. Trouble is they are taking the rest of Earth with them.

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