Santos’ brine dams in Queensland under the microscope

Santos’ brine dams in Queensland under the microscope

Produced water from coal seam gas extraction at Arcadia and Fairview (in the Hallett State Forest) is gathered and directed to centralised water management facilities where it is stored for treatment and beneficial reuse. It is the structures that store this waste that are the focus of this Environmental Protection Order (EPO) placing Santos’ brine dams in Queensland under the microscope.

Coal seam gas waste is a big problem for the gas industry. As yet there are no energy efficient and economical (read cheap) ways of being able to beneficially re-use this large and hazardous waste stream.

Santos prefer to use irrigation as their disposal option and this requires intensive treatment which occurs on site. The total combined irrigation area for Fairview is approximately 1,542 hectares and for Arcadia approximately 415 hectares (102 ha constructed and up to 250 ha planned for construction).[1]

This EPO was issued to Santos by the Queensland Government and has a 4-year history. Some of the recommendations in the EPO are serious and the timeframes for action have passed in many instances. A final report must be prepared by Santos before Friday 29 August 2025.

This EPO is issued on the following grounds:

  1. The department requires you to take reasonable measures to secure compliance with the “general environmental duty” pursuant to section 358(d)(i) of the Act. ‘A person must not carry out any activity that causes, or is likely to cause, environmental harm unless the person takes all reasonable and practicable measures to prevent or minimise the harm (the general environmental duty).’
  2. The department requires you to take reasonable measures to secure compliance with the following conditions Environmental Authority EPPG00928713, pursuant to section 358(d)(iii) of the Act:

(i) Condition H20 which states: ‘Each regulated structure must be inspected each calendar year by a suitably qualified and experienced person (SQEP)’; and

(ii) Condition H21 which states: ‘At each annual inspection, the condition and adequacy of all components of the regulated structure must be assessed and a SQEP must prepare an annual inspection …’

There are numerous recommendations across the eight dams, some of these dams are over 10 years old. The cluster of dams in the Hallett State Forest in Queensland needs careful and continuous monitoring to ensure no environmental harm is occurring due to the volume and proximity of the infrastructure.

It is reasonable to assume that current recommendations from more recent reports made within the past 12 months are still to be actioned. However, the community would expect that recommendations made in 2021/22 would have been attended to. This may be the case and there is some evidence to show that work is occurring or has occurred but not in all instances. At least two of the eight dams have been taken offline. We look forward to the final report.

Summary of Recommendations:

AWAF 1 Feed Buffer Dam (No. 1) Google Earth displays an image from 30/5/2023. Original construction appears to have occurred pre-2014.

The recommendations in the EPO indicate serious issues with this facility including the need for seepage investigation and repair works. Commencement of recording/reporting of leakage. Implementation of strategy to address/manage geomembrane liner integrity. Install a permanent seepage detection pit and repair piping erosion/hole features visible in the Google Earth image.

Bottle Tree Brine Dam A (No. 2) Google Earth displays an image from 18/5/2024. Original construction appears to have occurred pre-2018. Work appears to have occurred on the north-western side.

Final certification needed. Update Operations and Maintenance Manual to reflect recommended seepage monitoring requirements and TARPs. Commence recording/reporting of leakage/seepage rate. Small repairs.

F-HCS-04 Associated Water Dam (No. 3) Google Earth displays an image from 17/5/2023. Original construction appears to have occurred pre-2013.

Seepage return/monitoring system for leakage sump. Update the current operational plan to reflect outcomes of seepage investigation and repair works including recommended normal operating procedures, seepage monitoring requirements and trigger action response plans (TARPs); and (ii) Have the updated operational plan independently certified by a SQEP; and (iii) commence recording/reporting of leakage/seepage rate data for inclusion in future annual inspection programs; or (iv) provide the department with a signed positive statement, from an inspecting SQEP, which states both of the following: (a) it is not necessary to update the current operational plan to reflect outcomes of seepage investigation and repair works to include the recommended seepage monitoring requirements and trigger action response plans (TARPs); and (b) it is not necessary to commence reporting of leakage / seepage rate data for inclusion in future annual inspection reports.

F-HCS-04 Remote Brine Pond A (No. 4) Google Earth displays an image from 17/5/2023. Original construction appears to have occurred pre-2013. The Santos documentation available contains no mapping of where this dam is and there seems to be an error in the naming of other dams in the same document with repetition of naming (see below).

The EPO details the same recommendation as the above Associated Water Dam.

F-HCS-04 Remote Brine Pond B (No. 5) was photographed by NWPA on the 30/08/24. Google Earth displays an image from 17/5/2023. Original construction appears to have occurred pre-2013.

An enquiry was lodged with the Department of Environment and Science in relation to the torn liner. NWPA were not aware at the time that this dam was subject to an EPO and the Department did not mention it in their response “In December 2023, the department confirmed this pond to be non-operational and contain only rainwater. Santos advised the department that all connections to the dam are positively isolated and that if the pond is to be brought back online, rectification of the known liner issues will be addressed in line with EA conditions.”

This pond was previously used in conjunction with the adjacent (but now decommissioned) injection well facility.

The EPO reports recommendations to repair (seal) longitudinal cracks in crest asphalt and commence recording/reporting of leakage/seepage rate data for inclusion in future annual inspection programs. Recommendation R023 was to remove detached floating access-egress matting (pictured below) from the dam prior to operating the dam at elevated water levels.

F-HCS-04 Remote Brine Pond C (No. 6) – Santos’ mapping is unclear. Google Earth displays an image from 17/5/2023. Original construction appears to have occurred in 2013.

Undertake works to secure seepage return pipes in correct position, R-029. Other recommendations s/a Pond B.

F-HCS-04 Remote Brine Pond D (No. 7) – Santos’ mapping is unclear. Google Earth displays an image from 17/5/2023. Original construction appears to have occurred in 2013.

Repair (seal) longitudinal cracks in crest asphalt. Other recommendations s/a Pond B.

Mount Kingsley Dam A (No. 8) Pictured below. Google Earth displays an image from 18/5/2023. Original construction appears to have occurred in pre-2018.

Repair piping erosion features at multiple locations on embankment crest.

Regulated Dams involved in this EPO:

StructureLocationRecommendationsDate requiredCapacity StorageStorage productState Forest
1. AWAF 1 Feed Buffer Dam(Fairview) -25.746460° 148.944005°R006, R009, R008, R010Various dates, end date Monday 30 June 2025110 ML  Produced water (chemically amended)Yes
2. Bottle Tree Brine Dam A(Arcadia Valley) -25.176006° 148.837226°R013, R014, R016Friday 1 July 2024230 MLRO ConcentrateNo
3. F-HCS-04 Associated Water Dam(Fairview) -25.730530° 149.089591°R017, R018Friday 1 July 2024205 MLProduced waterYes
4. F-HCS-04 Remote Brine Pond A(Fairview)? Not included in Santos’ mapping  R020Friday 1 July 2024351 ML  RO ConcentrateYes
5. F-HCS-04 Remote Brine Pond B(Fairview) -25.766365° 149.026641°  R022, R023, R024, R026Various dates Friday 27 September 2024359 ML  RO concentrate  Yes
6. F-HCS-04 Remote Brine Pond C(Fairview) -25.740929° 149.071526°  R027, R029Various dates Friday 1 July 2024359 MLRO concentrate  Yes
7. F-HCS-04 Remote Brine Pond D(Fairview) -25.740929° 149.071526°R030, R031, R032Various dates Friday 27 September 2024358 MLRO concentrate  Yes
8. Mount Kingsley Dam A(Arcadia Valley) -25.257377° 148.872093°R037Friday 1 July 2024225 MLProduced water storageNo

NWPA are keeping a particular eye on the regulated structures (brine and associated water ponds and dams) in the Hallett State Forest which is in Queensland, east of Injune. Further information is being sought from the Queensland Government on the status of this EPO.

By Johanna Evans

[1] Coal Seam Gas Waste Management Plan GLNG Gas Field Development Project EPBC (2012/6615) 2012

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