QUEENSLAND’S MINE REHABILITATION REQUIREMENTS FOR VOIDS: ENSHAM CASE STUDY

2 Legal Interests and Operational Context of the Ensham Mine

The Ensham Mine is in the Bowen Basin in central Queensland,[i] located approximately 35 km north-east of the town of Emerald (population of approximately 14,300)[ii], 49 km north-west of Blackwater (population approximately 4,700)[iii] and has recently obtained Commonwealth approval for an extension project.[iv] It sits in the Nogoa River catchment in the Fitzroy Basin.[v] The legal interests and operational context of the Ensham Mine provide the setting for considering the legal rehabilitation reforms.

2.1     Legal Context: Mine Tenure and Other Legal Interests

The Mine is situated within an area defined by seven mining leases (ML7459 (Ensham 1), ML7460 (Ensham 2), ML70326 (White Hill), ML 70049 (Yongala), ML70365 (Maria), ML70366 (Dorrigo) and ML70367 (Vogla)) and two mineral development licences (MDL 217 and MDL 218) issued between 1993 and 2010.[vi] Mining lease 70049 sits on land owned by the Shaw family. The remaining mining leases are on land owned by the Operator, Ensham Resources Pty Ltd.[vii] The Western Kangoulu People are native title claimants of the Ensham Mine area.[viii] Although they do not currently have a registered native title claim, the Garingbal and Kara People have a connection to the land within Ensham’s existing mining leases.[ix]

Environmentally relevant activities of Ensham’s mining operations are undertaken pursuant to Environmental Authority EPML00732813 (Ensham EA).[x] The Ensham EA has had several amendments and corresponding effective dates over the life of the Mine.[xi] At the date of this writing (December 2021), Ensham was operating under the Ensham EA dated 3 September 2020.

As will be seen, the international character of the mine owners is noted in the community consultations about the mine closure options. According to that Ensham EA, the Ensham EA holders are: Idemitsu Australia Resources Pty Ltd (ACN 010 236 272) (Idemitsu), Bowen Investment (Australia) Pty Ltd (ACN 002 806 831) (Bowen) and Bligh Coal Limited (ACN 010 186 393) (Bligh).[xii] The three EA holders also comprise the Ensham joint venture, in which Idemitsu has 37.5% participating interest, Bowen has 15% participating interest and Bligh has 47.5% interest[xiii] (collectively these are referred to in this case study as the Ensham Joint Venture or Ensham EA holders). As Bligh is a subsidiary of Idemitsu, Idemitsu effectively has an 85% participating interest in the Ensham Mine.[xiv] Similarly, the Ensham Mine is operated by Ensham Resources Pty Ltd (ACN 011 048 678),[xv] the Operator, a wholly owned subsidiary of Idemitsu Australia Resources Pty Ltd.[xvi] Idemitsu Australia Resources Pty Ltd is a subsidiary of Idemitsu Kosan Co. Ltd, a Japanese energy and natural resources conglomerate that is listed on the Tokyo Stock Exchange.[xvii] Bligh Coal Limited is a subsidiary of Idemitsu Australia Resources Ltd and Bowen Investment Australia Ltd is a subsidiary of LG Corporation, a Korean company.[xviii]

2.2     Operational Context

The Ensham Mine is a thermal coal mine with surface and underground operations. Open-cut surface mining started in 1993. Underground operations opened in 2011 as a brownfields project –the Ensham Central Project. Major flooding occurred in 2008 and 2011, which sets part of the context for the mine rehabilitation regulation.

2.2.1 The Mine and Land Use

The Mine is variously described as comprising seven or eleven mining pits (Pits A, B, C, D, E, F and Y), as some are further subdivided (A Pit South, A Pit Central and A Pit North; F Pit South and F Pit North; and Y Pit South, Y Pit Central and Y Pit North).[xix] Underground operations are accessed through Pit C. These portals are also used to move extracted coal to the coal handling plant from where the coal, once processed, is transported by rail to the Gladstone Power Station and to port for export.[xx]

Post-mining land use will largely comprise grazing. Presently, the Nogoa Pastoral Company actively grazes “a large portion of [the] area [of]” ML 70326, ML 70365, ML7459, and ML 70366 as part of their pastoral activities.[xxi]

Ensham’s mining leases are scheduled to expire in January 2028. These can be extended under the Mineral Resources Act 1989 (Qld) (MR Act) upon application by Ensham (and approval by government).[xxii] Under the MR Act, the extension application cannot be submitted more than one year before the current term expires.[xxiii] Should Ensham seek to extend its leases, it need not submit an extension application until 2027. Ensham has proposed a “Life of Mine Extension Project”, which evidences an intention to submit an extension application that would extend the operations of underground bord and pillar operations into further zones and the mine life to 2037.[xxiv]

More than 1,550 ha of open-cut mine rehabilitation has occurred at the Mine since 2003. This progressive rehabilitation “equates to approximately one third of total mining disturbance”.[xxv] Following the Life of Mine Extension Project, underground rehabilitation would follow cessation of operations expected by 2037.[xxvi] Decommissioning and rehabilitation of extension project surface infrastructure would complete by 2043.[xxvii] This would include rehabilitation of Pits C and D, which will be used to access underground operations.[xxviii] The site would then be monitored for 10 years upon completion of rehabilitation works (to 2053), followed by a 2-year certification period.[xxix]

2.2.2 Flooding History

The 2008 and 2011 flooding at Ensham Mine, discussed later in this article, is relevant to site rehabilitation. The Ensham Mine was a case study in the Queensland Floods Commission of Inquiry (2012), following the late 2010 to early 2011 Queensland floods.[xxx] The Mine is adjacent to the Nogoa River, with some pits located partially in the floodplain. In 2008, floodwaters breached the levee banks and inundated four open-cut coal mining pits with an estimated 150,000 ML of water that submerged a dragline.[xxxi] Following this, the Queensland Government authorised Ensham to discharge 138,000 ML of the water between February and September 2008.[xxxii] Increased salinity was found in water quality monitoring in September 2008, which affected water supplies and reduced drinking water quality (for humans and livestock) in some downstream communities.[xxxiii] The impact on water supplies caused community concern, and negative media coverage led Ensham to cease dewatering the pits voluntarily, despite being authorised to continue the discharge.[xxxiv]

After the 2008 floods, Ensham built large levees that were designed for a one in 1,000-year flood.[xxxv] (Presently, Pits B, C and D are protected by “0.1% Annual Exceedance Probability regulated structured levees”.)[xxxvi] The levees prevented the Nogoa River and its tributaries from flooding Ensham’s open pits in the 2010-11 wet season. However, heavy rainfall at the mine site increased surface water, which flooded active pits that were already holding water from the 2007-08 season, requiring an authorised release of water into the Nogoa River.[xxxvii]

The experience of the 2008 floods led the Queensland government to develop the Model Water Conditions for Coal Mines in the Fitzroy Basin Guideline (Fitzroy Model Conditions) pursuant to the EP Act[xxxviii] which were subsequently incorporated into EAs. The Fitzroy Model Conditions’ restriction on water release was found to be a contributing factor to mine flooding in 2011, as mines could not release water ahead of the rainy season. The Queensland government revised the Fitzroy Model Conditions after industry’s and government’s experience of the water release authorisation process in the 2011 floods, permitting a new regime of flood release.[xxxix] There is a potential question whether authorised flood water releases might cause offsite rehabilitation issues, which we assume have been addressed in the authorisation of the amended Fitzroy Model Conditions regime and do not attempt to address them here.

A timeline of key events for the Ensham Mine is provided below in Table 1, which includes tenement awards, key legislation and regulatory events, physical events (flooding) and scheduled mine closure.

Table 1: Ensham Mine Timeline

2.3     Rehabilitation Legal Reforms – PMLUs, NUMAs and Voids in Flood Plains

Among Queensland’s legislative reforms[xl] is the requirement that EA holders develop and implement a PRCP and PRCP Schedule. The PRCP Schedule must propose the post-mining land use(s) and non-use management area(s) (as applicable) and their milestones schedule, compliance with which will lead to the EA eventually being surrendered (and terminate the tenement holder’s obligations and liabilities).[xli]

A post-mining land use (PMLU) means “the purpose for which the land will be used after all relevant activities for the PRC Plan carried out on the land have ended”.[xlii] The land must be rehabilitated to a stable condition that can support a viable use that is unrelated to mining and is appropriate for the region in that it is consistent with relevant land use planning schemes, and is either consistent with a previous permitted use or it delivers better environmental outcomes.[xliii] Some examples of PMLUs are native ecosystems, grazing, agriculture, land fill and water storage.[xliv]

A non-use management area (NUMA) is defined as an “area of land the subject of a PRC Plan that cannot be rehabilitated to a stable condition after all relevant activities for the PRC Plan carried out on the land have ended”.[xlv] The intent of this is that “the areas are minimised to the extent possible, which includes, for example, minimising area, volume of materials and level and number [of] distinct areas. Each [NUMA] is expected to be located to prevent or minimise environmental harm.”[xlvi] Thus, a NUMA is excepted from rehabilitation requirements (because it cannot be rehabilitated to a stable condition) and will be “managed” instead through milestone improvements.[xlvii]

The NUMA classification is available where the risk of environmental harm from non-rehabilitation is confined to the relevant tenement area and not rehabilitating the land is in the public interest.[xlviii] However, by section 126D(3), the NUMA classification is unavailable for voids that are in flood plains. These voids (in whole or part) must be rehabilitated to a “stable condition”.[xlix] Land rehabilitated to a “stable condition” must achieve three requirements: it must be (1) safe and structurally stable; (2) non-polluting; and (3) sustain a PMLU[l] [emphasis added].

As mentioned above in Part 1, Queensland’s mine rehabilitation reforms have a grandfathering/
transitional scheme for pre-existing mines that can present a “land outcome document” under the EP Act’s transitional provisions. Those pre-existing mines can utilise different (lesser) rehabilitation requirements for voids in flood plains than those required for new site-specific mines.

2. Rehabilitation Regulation and Voids—Ensham Mine Rehabilitation Planning

This part tells the story of the Ensham Mine rehabilitation planning process to provide context for the observations on that process set out in Part 4. It identifies the generic residual void risks and how the Ensham EA Holders navigated the rehabilitation reforms to present a land outcome document that entails the maintenance of residual mine voids in a floodplain.

3.1     Residual Void Risks

A four-page paper entitled “Rehabilitation of Final Voids” was included among information published by the Queensland Department of Environment and Science under a 2019 Right to Information request (not made by the authors of this article) that concerned the Ensham rehabilitation. While the report is not specific to Ensham, it describes risks associated with rehabilitation of final voids, such as those at the Ensham Mine, and is useful context for this case study.[li] Excerpts from this report are quoted in Box 1 and Box 2 below.

Box 1: Final Voids[lii]

Box 2: Floodplain Voids[liii]

In summary, there are good reasons not to rehabilitate mine voids by making them into pit lakes, especially when the voids are located on flood plains.

3.2     Development of Residual Void Rehabilitation Criteria – Residual Void Project

The Ensham EA’s “rehabilitation success criteria” for the Mine’s residual voids were developed through a residual void study. This requirement was in the 28 February 2017 EA[liv] and the 9 August 2018 EA[lv] condition G20, which mandated that Ensham complete a Residual Void Project (RVP) by 31 March 2019. The RVP study commenced in May 2017.[lvi]

To inform the RVP study, Ensham established a community stakeholder group, the Ensham Residual Void Project Community Reference Group, to “create an open forum for discussion” on the rehabilitation options.[lvii] The Reference Group Charter set out the Group’s objectives, membership, responsibilities and roles.[lviii] The membership comprised three neighbour representatives, two from the Central Highlands Regional Council, one from the Central Highlands Cotton Growers and Irrigators Association, one from Fitzroy Partnership for River Health, one from the water utility, Sun Water, and one “community representative”, plus an independent chair and minutes secretary. Visitors and observers could be invited, subject to the approval of Ensham. There is no indication that the Shaw family or native title claimants (see Part 2.1 above) participated in the Reference Group. Some information was to be kept confidential, but meeting minutes were recorded and published for the seven meetings (the first was on 4 October 2017 and the last on 14 February 2019). These meeting minutes documented questions posed by attendees and Ensham’s responses. They are available online[lix] and provide insight into stakeholder concerns about management of residual voids, some of which we present here.

Three points of substance became apparent at the first meeting on 4 October 2017. First, the impetus for the RVP was that, in April 2017, the Queensland Department of Environment and Heritage Protection rejected the Rehabilitation Management Plan and Residual Void Management Plan submitted by Ensham in March 2016 because it did not include filling the mine voids. Ensham contended that the cost of filling the voids would put it “at a high risk of going out of business”. The issue was “escalated” in business and government, resulting in the government’s decision “to give a study period to gain scientific evidence and community feedback to come up with a solution”. This suggests that there was a basis for at least some people in the community to expect that mine voids would be re-filled.

Second, as noted above, Ensham is predominantly owned by Idemitsu, a Japanese company. The Ensham representative mentioned that:

Idemitsu is a Japanese company and are very sensitive to their reputation, especially when it comes to the environment as they don’t want to leave a bad legacy. The study period will allow Ensham time to find out if there is science that can help Ensham consider appropriate alternates. This group is important and we are open to all thoughts, ideas and challenges.[lx]

Idemitsu’s vision for the proposed Ensham rehabilitation is documented in a conceptual video.[lxi]

Third, three rehabilitation options were being considered.

Option 1 was variously described as the levee backfill or landform option. Under Option 1, existing levees would be retained, and a permanent substantial landform created by backfilling behind and on top of the levee. This option would require annual inspections to ensure structural integrity.[lxii]

Option 2 was described as engineered flood mitigation and irrigation, combining flood management with beneficial water use. Under this option, flooding would be mitigated by directing water in flood events into pit voids. The pits could provide water to be used by the community such as through recreation or irrigation.[lxiii] Flood mitigation and beneficial use encompassed all pits (A-Y), with Pits A, B, C and D to be used for water storage.[lxiv] Water quality management was considered the significant issue for Option 2.[lxv]

Option 3 was to backfill all the voids in the floodplain up to the probable maximum flood level.[lxvi] This was described as the baseline for the residual void study as it was the regulator’s preferred option.[lxvii] It was not Ensham’s preferred option due to “associated cost with moving significant volumes of dirt”[lxviii] and that “it would also require significant disturbance of areas already rehabilitated”.[lxix] Ensham’s representative at the 4 October 2017 meeting responded affirmatively to the question of whether “reluctance to fill the void [was] due to cost”.[lxx]

A review of the meeting minutes suggests that these three options evolved and were refined as findings were made during the residual void study. For example, in a later meeting, Ensham explained that option 2 was not the regulators’ preferred option, “as they do [not] feel they can approve a reservoir for the use of the land [as] [t]he current post-mining lease land use is grazing for low wall spoil”. Ensham further explained that:

We have 2 options with regards option 2 and how this is managed within the RVP – (i) argue with government and lodge an application with reservoir, which doesn’t give anyone any certainty; or (ii) we push forward with Option 2 as the landform design and stay with grazing as post mining land use. This allows us to preserve the landform as a potential use of reservoir for the possible application for the use of a reservoir put forward at a later date.[lxxi]

Regarding establishing the beneficial use, it was further explained:

It is about 135 million [dollars] to get the irrigation set up. Idemitsu is not paying that and have been clear on this. There are other opportunities out there for funding assistance if the reservoir was supported. Idemitsu aren’t walking away from this, it was always going to be this price for Option 2 and we are willing to work with people to help get this going. Government wants to lock in a land use and submit another application for water storage at a later date. What we have done is keep the land use for all options as grazing as post mining land use for now. The water holding capacity for Option 2 will remain the same, we just can’t get water in or out.[lxxii]

The social impact assessment, developed as part of the voluntary Environmental Impact Statement (EIS) under the EP Act, for the proposed life of mine extension project reveals that RVP community stakeholders were concerned about the social impact of water quality and flooding risk.^[lxxiii] The EIS explained that “significant social impacts were not identified” with the exception of: Option 2 (flood mitigation and beneficial use), which was likely to positively impact water security in the region; and Option 3 (backfilling) with the increased flooding and sediment load risk, which was likely to negatively impact mental health of landholders downstream, but positively impact on the local landholders’ “visual amenity”.^[lxxiv]

The three options of the residual void project were assessed using a triple bottom line method, which took account of environmental, social and economic factors. The final report for the Residual Void Project (which is not readily available but was found on Lock the Gate’s website) recommended Option 2 on the basis that it was the only one of the three options that “passe[d] all 14 stage gate questions for Environment, Social and Economic considerations”.[lxxv] The recommended option 2 did not have a post-mining beneficial land use for water; instead, the beneficial use would be grazing and a native bushland corridor. However, the final report also highlighted:

Both the CRG [Community Reference Group] and Central Highlands Regional Council have provided feedback that in light of the future reservoir opportunity created by the retention of the design criteria … they support Option 2 as the final preferred option. There have been clear discussions that any future reservoir would be subject to a separate approval process to this option.[lxxvi]

The beneficial use change from water reservoir to grazing and instalment of a bushland corridor was questioned in the final Community Reference Group meeting. A questioner asked, “There is quite a material change as to what Option 2 is on the table right now, What do we call it now?” Ensham replied:

[I]t is still beneficial use. The government is quite process based and it was always going to be a long shot for them to approve the irrigation straight away. It is important to preserve the landform for the potential use of the land as water storage.

Are we walking away from the reservoir option, no. This is about how can we work effectively with the region to get this in motion. There is a lot of licensing and approvals for dams to be approved by government. They want certainty in the EA. The decision was made that we would keep Option 2 alive and recognise the government’s barriers and either fight with them or work with them. We can morph the options as we move through the study, though if we changed names now we have problems in the Stage 4 report. The report has a full list of the options and lists any changes.[lxxvii]

The beneficial use change also prompted questions about the triple bottom line assessment at the final Community Reference Group meeting. The meeting minutes record that someone asked: “When entering and answering the questions in the TBL [triple bottom line assessment], was this done based on Option 2 landform only and not the reservoir”? Ensham responded, “Yes”. A follow-up question asked: “Are you still claiming the social benefits of Option 2 with knowledge that this isn’t going to be a reservoir”? Ensham responded, “The economic benefit based on the reservoir has been peeled out / removed” and “Option 1 would be similar to Option 2 when the area will be nearly the same for Option 1”. Ensham agreed to “go back and check this report to ensure Option 2 is similar to Option 1 for the social impacts based on no longer having a reservoir in Option 2”.[lxxviii] Ensham’s proposed transitional PRCP describes the recommended option (and ultimate outcome) as “a modified Option 1 with potential future beneficial use and water storage”.[lxxix]

The RVP’s social impact assessment suggests that the recommended option is inconsistent with community preferences (the relevance of this is discussed below in Part 4.3).

[A]cross all stakeholder groups consulted (key stakeholders, local and regional community residents and Ensham employees), Preferred Option 2 emerged as the key option preference (92), followed by Preferred Option 3 (29) and Preferred Option 1 (12) … key stakeholders consulted were more divided in their option preferences between Preferred Option 2 – Beneficial Use (16) and Preferred Option 3 – Backfill to PMF (19); whereas, both local and regional community residents (42) and Ensham employees (34) were more likely to demonstrate a clear preference for Preferred Option 2.[lxxx]

Idemitsu (as majority owner of the Ensham Mine) has been accused of “attempting to backflip on its original commitment to re-fill and rehabilitate [sic] 11 mining pit voids, including three on the Nogoa River floodplain”.[lxxxi] However, Idemitsu has emphasised that these residual voids are not unrehabilitated. The Ensham Life of Mine Extension Project EIS submission responses register includes a response to a submission that “Ensham Mine has amended a previous EIS commitment to rehabilitate mine voids and is subsequently leaving an everlasting scar on the Nogoa River floodplain”.[lxxxii] Idemitsu responded as follows.

The rehabilitation outcomes for the Ensham mine were assessed and determined through the extensive and comprehensive scientific studies undertaken through the Residual Void Project (RVP) submitted in 2017 and the amendment to the Ensham Environmental Authority (EA) in 2020. The Ensham open-cut mine will not have unrehabilitated residual voids as a domain in the postmining landscape, rather, existing open-cut voids are to be partially backfilled and rehabilitated in accordance with the EA. The rehabilitation outcomes for the open-cut mine in the floodplain are specified in the EA.[lxxxiii]

The outcome of the RVP is relevant as it determined the rehabilitation requirements for the Ensham residual voids under the “land outcome provisions” of the EP Act for pre-existing mines,[lxxxiv] rather than the s 126D(3) rehabilitation obligation. This is discussed in Part 3.3 below. The RVP result also highlights a difference in community expectations versus rehabilitation requirements for voids situated wholly or partly in a flood plain. Some in the community had thought rehabilitation in this situation meant re-filling of the voids. However, as discussed above at Part 2.3, “re-filling” is not, since the 2018 reforms, the section 126D(3) rehabilitation standard for voids in a flood plain; “stable condition” is. Nevertheless, as pointed out in Part 4.3 below, when misunderstandings about regulatory requirements are added to access to information issues, there can be challenges in community consultation addressing expectations.

3.3     Ensham as a Pre-Existing Mine under the Rehabilitation Reforms

Ensham’s Residual Void Project and associated EA amendments occurred around the time of Queensland’s mining rehabilitation reforms. The MERFP Act commenced 1 April 2019.[lxxxv] The transitional provisions of the MERFP Act (as applied to the EP Act) have created two classes of mine rehabilitation requirements – new mines and mines that existed at the effective date of the rehabilitation reforms on 1 April 2019. All mines, new and pre-existing, have become subject to the new closure planning regime but the transitional provisions have created a process to avoid retrospective application of certain new requirements where an existing mine has an approved mine rehabilitation outcome.

3.3.1  The Land Outcome Document

The final Ensham RVP report states: “This Residual Void Project report, including the Rehabilitation Management Plan is intended as a ‘land outcome document’ under the Mineral and Energy Resource (Financial Provisioning) Act 2018”.[lxxxvi] A land outcome document is also referred to as a “pre-existing NUMA”.[lxxxvii] The statutory definition of “land outcome document” is provided below in Box 3.

The transitional provisions of the EP Act (as amended by the MERFP Act) address the effect of land outcome documents in displacing the requirement for an Environmental Authority holder to give the administering authority a proposed PRC Plan that complies with section 126D(3).[lxxxviii] Where a land outcome document is applied, it establishes the rehabilitation requirements for residual voids, including voids on floodplains, rather than the EP Act’s section 126D(3) requirements.[lxxxix] A residual void can be an outcome for the land where that outcome under the land outcome document is “the same or substantially similar to a NUMA”.[xc] Thus, it appears that Idemitsu intended the final report of the RVP would determine the rehabilitation requirements for the residual voids rather than section 126D requirements of the EP Act.

Box 3: Definition of Land Outcome Document[xci]

We suggest that the Ensham RVP final report was submitted as a pre-existing NUMA under subsection (b) of the “land outcome document” definition, as it was a required condition under the February 2017 Ensham EA. However, we note Ensham’s proposed transitional PRCP (submitted to the regulator in June 2021) identifies the 3 September 2020 EA as the land outcome document under subsection (a) of the land outcome document definition.[xciii] This would be due to the EA having incorporated the outcome of the RVP final report.

The legislative history of the MERFP Act is clear that the land outcome document as a grandfathering tool was an intended option for existing mines:

The new rehabilitation provisions [of the MERFP Act] do not impose retrospective requirements to rehabilitate as requirements to rehabilitate are included in existing conditions on environmental authorities… For existing mines, holders of an authority will be required to submit their PRC plan upon receiving a notice. In preparing their PRC plan, the holder will be asked to translate their authority rehabilitation conditions into milestones and milestone criteria. For example, if the proponent’s authority sets out a proposed post mining land use and completion criteria for that land use, there will be no change to that commitment. The proponent will be required to reformat those commitments into the PRCP schedule which may include developing milestones to achieve that post mining land use. This also applies to non-use management areas.[xciv]

Rehabilitation concessions available to pre-existing mines that subscribe to the land outcome document scheme under section 754(2) of the EP Act are also emphasised in the PRC Plan Guideline.

Where a NUMA has already been identified in a land outcome document and is able to be transitioned into the PRCP schedule, the applicant is not required to comply with sections 126C(1)(g) [stating the reasons the NUMA cannot be rehabilitated to a stable condition] or (h) [requirement to provide copies of reports or other evidence relied upon for proposing the NUMA] or 126D(2) [conditions for an area to qualify as a NUMA in a PRCP schedule] or (3) [residual void wholly or partially in a flood plain must be rehabilitated to a stable condition] of the EP Act.[xcv]

These exemptions are reflected in Ensham’s proposed transitional PRCP. The proposed Ensham PRCP states, “[a]s NUMAs at Ensham have already been identified in a land outcome document, i.e., EA EPML00732813, this PRC Plan is not required to comply with sections 126C(1)(g) or (h) or 126(D)(2) or (3) of the EP Act”. Furthermore, “[a]s the pre-approved NUMA locations have been specified in the EA … Ensham is not required to undertake floodplain modelling as part of this plan”.[xcvi]

3.3.2  Ensham’s Residual Voids as NUMAs

Ensham’s EA was updated following the Residual Void Project. The rehabilitation success criteria, in Appendix 3 of the 3 September 2020 Ensham EA, set out four goals for each rehabilitation feature – (1) safe, (2) non-polluting, (3) stable, and (4) land use – and specifies the objectives, indicators and completion criteria for these.[xcvii] These goals should be compared with the EP Act’s definition of “stable condition” (see Part 2.3 above). Under the present Ensham EA (dated 3 September 2020) and Ensham’s proposed PRCP, several residual voids located in the Nogoa River floodplain will remain as NUMAs. This means they will be “rehabilitated” to be safe and stable and non-polluting (two of the three conditions required for “stable condition”); however, they will not have a post-mining land use. Therefore, they will not comply with the section 126D(3) obligation.

Ensham’s approved NUMAs (residual voids) are highwalls and groundwater daylighting areas.[xcviii] For example, rehabilitation success criteria under the Ensham EA for residual voids include highwalls for Pits A, B, C, D and E and a permanent, stable flood structure landform.^[xcix] Residual voids must also “act as groundwater sinks to the receiving groundwater environment into perpetuity: (a) A Central pit; (b) A North pit; (c) B pit; (d) C pit; and (e) D pit”.^[c] The land use for these five pits is “no land use beyond containment of [groundwater daylighting] water”.[ci] According to Ensham’s proposed transitional PRCP,[cii] while Pits A Central, A North, B, C and D will be partially backfilled, they will be NUMAs as they will have groundwater daylighting areas (which is not a post-mine land use as defined in the EP Act), noting that “[g]roundwater in the coal seams is also saline and not suitable for stock water supply or irrigation”.[ciii] In contrast, another four pits – Pits A South, E, F and Y – are not characterised as voids, as they “will be partially backfilled to support a final land use of grazing”.[civ] However, as the RVP meeting notes highlight, “Pit E will only be partially backfilled, there will still be a residual void in it”.[cv] This emphasises a technicality of the legislation – a void is not a void if it has a PMLU.

A diagram of the groundwater daylighting areas is provided in the Ensham proposed transitional PRCP.[cvi] The groundwater daylighting areas will cover 146 hectares.[cvii] The Ensham proposed transitional PRCP highlights that “[d]espite being pre-approved in land outcome documents, the area of NUMAs has been minimised and represents less than 5% of all disturbed lands”.[cviii]

3. Observations

This part considers issues in Queensland’s mine rehabilitation regulations raised in the Ensham case study.

4.1     Transitional Regulatory Design and “Land Outcome Documents”

The first transitional regulatory design challenge concerns the availability of NUMAs for voids in floodplains of pre-existing mines. Under section 126D(3) of the EP Act, where a residual void is in a floodplain, the land must be rehabilitated to a “stable condition”[cix] and cannot be a NUMA.

Ensham’s rehabilitation will result in voids in a floodplain (some of which are NUMAs and some which are PMLUs). Residual voids in floodplains may be allowed under a land outcome document (as transitioned into a PRCP and PRCP schedule). As the legislative history shows, the intent of this exception was to provide certainty to industry during regulatory reform. These transitional arrangements exist to protect investments made under one set of rules from regulatory risk necessary to comply with new legislative schemes. However, it could be deemed inconsistent with the spirit of regulatory reforms in creating two classes of rehabilitation schemes. It also raises a question about the application of the “stable condition” requirement that “there is no environmental harm being caused by anything on or in the land”.[cx] For NUMAs in flood plains, void conditions will evolve, which may present risks as noted previously in Part 3.1, Box 1 and Box 2.

In the case of Ensham, the voids will become increasingly saline, although they will be contained (and hence non-polluting in accordance with the EP Act).[cxi] The voids will remain long after Ensham (Idemitsu as the tenement holder) surrenders the mining leases, leaving future generations to manage the consequences. For example, a NUMA management milestone in the proposed Ensham PRCP to ensure safety is that the area will be “[b]unded, fenced and signed to exclude humans and stock”.[cxii] This suggests it will be necessary for generations centuries in the future to maintain fencing and signage to exclude humans and stock. While Ensham and other existing EA holders have the right to pursue a “pre-existing NUMA” for residual voids in flood plains under the land outcome document provisions, which may be a preferred economic outcome for them, whether they should do so raises issues of social licence, sustainability and justice of future generations that are beyond the scope of this paper.[cxiii]

Secondly, it is reasonable to assume that Ensham would not be the only pre-existing open-cut mine to avail itself of these provisions and seek to have void rehabilitation governed by a land outcome document under sections 750 and 754(3) of the EP Act.[cxiv] It is unclear what, if any, cumulative risks/consequences these NUMAs in flood plains will have for Queensland.

Finally, management of the Ensham Mine’s residual voids has been an issue of concern and interest for some stakeholders. It appears that, at the time the Ensham Central Project was proposed in the 2000s, the rehabilitation intention for voids was that those in the Nogoa flood plain would be filled, while those outside the flood plain would be residual. For example, in the Environmental Impact Statement (EIS) Assessment Report for the Ensham Central Project, among the Project’s identified major impacts on land resources were: “an increase in the minimum width of the floodplain to 2.3 km in the post mining phase” and “final voids outside of floodplain areas remaining at the end-of-mine life”.[cxv] In addition, in February 2017, the regulator (Department of Environment and Heritage Protection, the DES predecessor) advised Ensham that the regulator’s position was that Ensham was to “reinstate the floodplain by backfilling any open-cut mining voids within the floodplain to approximately pre-mining area surface level, as outlined, agreed and committed to within the Environmental Impact Statement 2006 and Environmental Management Plan 2010”.[cxvi] These statements and plans may have contributed to an expectation by some in the community that voids would be re-filled, contrary to present rehabilitation requirements for the Ensham Mine. Again, while Ensham has the right (under the 2018 legislative reforms) to pursue the NUMA regime for rehabilitation, it may have done so contrary to some community preferences.

4.2     Progressive Rehabilitation and Pre-Existing Mines

The second challenge in Queensland’s mine rehabilitation framework highlighted by the Ensham case study concerns progressive rehabilitation and mines already in existence at the time of the 2018 reforms. Progressive rehabilitation was subject to the recent Queensland mining rehabilitation reforms. An issue for concern is whether the reforms will improve rehabilitation outcomes of voids. In cases such as Ensham, slow rehabilitation of large, pre-existing mines may perpetuate residual voids in rehabilitation outcomes.

Progressive rehabilitation is a requirement of the Ensham EA: “Land significantly disturbed by mining activities must be progressively rehabilitated in accordance with the Rehabilitation Management Plan required by condition H3”.[cxvii] According to Ensham’s proposed revised PRCP (in preparation December 2021), Ensham had rehabilitated a total of 1,647.4 hectares of land (to accord with PMLUs of cattle grazing, native bushland corridor and Boggy Creek diversion), of which 662.83 was certified (Ensham has not yet sought certification for 984.6 hectares of rehabilitated land). Ensham has 3,297.3 hectares of rehabilitation remaining (approximately 63% of this has a PMLU of cattle grazing).[cxviii] The scale of remaining rehabilitation task likely generated, from an economic perspective, a residual void study recommending residual voids as a rehabilitation outcome.

By the time a mine enters its closure phase, “an ideal goal is to have the majority of the mine already progressively rehabilitated and [where relevant] geochemically rendered inactive”[cxix] (noting that not all mines, such as Ensham, are geochemically active). Ensham’s December 2021 figures (quoted above) are several years before the scheduled cessation of Ensham’s open-cut operations. Therefore, it is expected that Ensham will continue to progress rehabilitation over the next few years in accordance with its PRCP and Schedule. Some of the land that has been progressively rehabilitated may have to be re-disturbed during post-mine rehabilitation in order to partially backfill pits and re-establish grazing. Further research would be required to ascertain broader industry practice and attitudes in respect of this “ideal goal”.

Finally, an obvious observation is that progressive rehabilitation assumes the mine is operating. Thus, Queensland’s progressive rehabilitation reforms may not address the risk of residual voids where existing open-cut mines have had slow progressive rehabilitation to date. This risk is higher where mines can and do make use of the land outcome document “exception” discussed above. While there may be a reduction in risk for Ensham as it continues its progressive rehabilitation and approaches closure of the open-cut operations, this broader industry risk is highlighted by an observation Ensham made in its PRCP: “Following approval of the current application for certification of progressive rehabilitation in 2021, Ensham will have more certified rehabilitation than any other opencut coal mine in Queensland” [emphasis added].[cxx]

4.3       Transparency and Community Expectations

Information transparency is relevant to accountability and public confidence in processes and outcomes. Relevant information can form “part of an important regulatory process to ensure that significant mining projects are undertaken in compliance with the relevant environment protection legislation and regulations”.[cxxi] The Ensham case study highlights several issues of transparency and community expectations in Queensland’s mine rehabilitation regulatory framework.[cxxii]

4.3.1  Access to Information

The use of the Right to Information Act 2009 (Qld) (RTI Act) has the potential to enhance equitable access to information within Queensland’s regulatory framework for mine rehabilitation. The Queensland Department of Environment and Science makes information, the subject of these requests, publicly available. As an example, in the context of this study, information requested by Lock the Gate and the Wanditta Pastoral Company was made available online to the public, and it was relevant to the study’s objectives.[cxxiii] The RTI Act serves to improve transparency unless, on balance, disclosure would “be contrary to the public interest”.[cxxiv] However, mine rehabilitation reforms may hinder the usefulness of the RTI Act, specifically regarding contributions to the financial provisioning (assurance) scheme, effective 1 April 2019.[cxxv]

Queensland’s financial provisioning scheme is intended to incentivise progressive rehabilitation by setting the primary liability for an annual financial assurance contribution at a prescribed proportion of the current estimated rehabilitation cost up to $450,000,000,[cxxvi] and any cost beyond that must be assured by posting a surety.[cxxvii] The amount of funds posted by an environmental authority holder as surety for the financial assurance for estimated rehabilitation cost is exempted from public disclosure under the RTI Act.[cxxviii] In addition to the RTI Act, public interest exclusion from disclosure (see above), information is exempt from disclosure if it falls within ss 80(2) or 82(2) of the MERFP Act. These sections of the MERFP Act address a duty of confidentiality for the scheme manager (s 80(2)) and very limited exceptions for disclosure of confidential information (for assisting certain government chief executives with the performance of legislated functions) (s 82). “Confidential information”[cxxix] includes information about contributions or sureties paid under Part 3 of the MERFP Act (the financial assurance and estimated rehabilitation cost scheme).[cxxx] Given the concerns raised above about progressive rehabilitation of mature mines and residual void risks, it seems this confidential information protection could reduce public accountability of the operation of this scheme as it concerns residual voids and mature mines.

Beyond the role of the RTI Act, there are concerns about the ease of third-party access to information generated in the administration of regulatory processes involving consultation about rehabilitation, such as the PRCP and Schedule. This information is held by and between the regulator and mining company (in this case study, Idemitsu). Access to rehabilitation information by third parties (such as community members) is hindered through processes/ways of doing business, such as in the way information disclosure is managed by the regulator. For example, when research on this study commenced in July 2021, PRCP information was only made publicly available by a person making a public register information request to the regulator. Currently, the response time is estimated to be “10–75 business days”, depending on the size and complexity of the request.[cxxxi] While the regulator has recently made PRCPs available online, the previous process still applies to prior versions of environmental authorities.

Information access may also be hindered by informal arrangements. In the 13 December 2018 meeting of the Ensham Residual Void Study Community Reference Group, the local landholders inquired about how the regulator would review their concerns and response to Idemitsu’s triple bottom line assessment.[cxxxii] The landholders were advised that discussions between various impacted neighbouring parties were confidential.[cxxxiii]

Finally, under the EP Act, a proponent must detail the community consultation undertaken in the development of a PRCP and how that consultation regarding rehabilitation under the PRCP will be ongoing.[cxxxiv] This includes compliance with the EP Act’s public notification requirements.[cxxxv] However, the PRCP Guideline states that public notice is not required for pre-existing NUMAs: “The public notification requirements, under Chapter 5, Part 4 of the EP Act, do not apply to pre-approved PMLUs or NUMAs, or, where there is a pre-approved NUMA but the PRCP schedule has proposed the land as a PMLU instead (section 755B of the EP Act)”.[cxxxvi] This approach results in a reduced level of public transparency of the PRCP. Recall that Ensham submitted its PRCP to the regulator in 2021. It is understood by the authors of this case study that public notice of the PRCP was not provided, which would be consistent with the Guideline’s EP Act interpretation.

4.3.2  Community Consultation and Expectations

Related to transparency, we make three observations which concern community consultation and management of community expectations. First, while the transitional provisions provide some exclusions to ss 126C and 126D of the EP Act, they do not exclude the requirement that the PRCP applicant must state the extent to which the proposed NUMA as identified in the proposed PRCP schedule “is consistent with the outcome of consultation with the community in developing the [PRCP]”.[cxxxvii] This means the PRCP applicant may need to demonstrate some level of community agreement/acceptance of the NUMA for it to be proposed. It is not clear that this was achieved in the Ensham land outcome document (where the land outcome document was the RVP final report) or in Ensham’s proposed transitional PRCP.

The final report of the RVP (the originally intended land outcome document) describes community engagement, such as through the RVP Community Reference Group. [cxxxviii] The proposed transitional PRCP also describes community engagement.[cxxxix] However, it is not clear that the RVP void rehabilitation recommendations are “consistent with the outcome of consultation with the community in developing the plan”.^[cxl] This notion is founded in some of the concerns reflected in the RVP Community Reference Group meeting minutes discussed above in Part 4.3.1, including a preference by some participants that the voids provide beneficial use through a reservoir or that they would be rehabilitated by being re-filled. Also, as mentioned previously in Part 3.2, the social impact assessment for the RVP (included in Ensham’s proposed PRCP) showed community preference for Options 2 and Options 3 over the recommended rehabilitation option.

Secondly, assuming Ensham’s rehabilitation recommendations are consistent with the EP Act, this raises issues around the meaning and standards of “consultation” in the legislation, including quality of community consultation, whether and how such engagement is meaningful and how it is measured. It also raises issues concerning changes in community expectations over time and the interests of future generations (and their lack of consultation), particularly in cases where rehabilitation takes decades to achieve. Finally, in the case of Ensham, the RVP revealed government was not supportive of changing the PMLU to support the beneficial use of Option 2 in the RVP. This raises the question of government’s role in facilitating a PRCP applicant’s ability to propose a PRCP schedule that is consistent with community consultation outcomes.

Finally, the dynamic between community preferences and regulatory requirements for rehabilitation also raises another issue about establishing and managing community expectations. As mentioned above in Part 4.1, some members of the community had the expectation that “rehabilitation” meant “re-filling”. Rehabilitation is an ambiguous term, which is subject to different interpretations and meanings. There are several approaches by which land can be “rehabilitated” and words to describe it (such as reclamation or restoration).[cxli] Not every mine site is suited for each of these, such as where the site has highly modified the landform or ecosystem, which may be the case in open-cut mines.[cxlii] In some cases, community preferences may be technically or economically unachievable, which brings to question how mining companies and government should address this expectation-versus-reality mismatch.

4. Conclusion

The Ensham Mine has been in operation since 1993 and is approaching closure (although underground operations were extended in June 2023). The EA has been amended several times across this nearly 30-year history. These amendments reflect operational changes (such as project expansions with new mining leases and addition of underground mining operations), regulation (such as following the Queensland floods in 2008 and 2011) and project maturity (such as requirements to undertake the Residual Void Project and subsequent EA amendment to identify the rehabilitation success criteria consistent with the Residual Void Project’s recommendations).

This review of Ensham’s impending closure and rehabilitation standards highlights several challenges in Queensland’s recently reformed regulatory framework for rehabilitation of open-cut mines. In the case of Ensham, the transitional provisions perpetuate existing rehabilitation plan outcomes with residual voids that would otherwise be disallowed under the MERFP Act. It may be that insufficient or slow progressive rehabilitation of other mature mines may also perpetuate these outcomes. Finally, concerns with community consultation and transparency in the operation of the regulatory framework may further impair the fulfillment of the rehabilitation reforms.

There are many issues of mine rehabilitation for large complex mines with a long history. While this case study reviewed Ensham, it is not likely to be the only mine in Queensland facing void rehabilitation issues. However, this study reveals that the regulatory reforms may not address certain risks faced/created by existing mines. It is not clear that sections of the community concur with the regulatory outcomes and are confident of the post-mine future. While pre-existing mines have the legal right to pursue the NUMA classification for residual voids in flood plains under the transitional provisions of the rehabilitation reforms, it is questioned whether and why such should be pursued in the face of opposition or different preferred post-mining land use of the voids by sections of the community. If there really is such uncertainty, it may be better to resolve it before Ensham prepares a final rehabilitation report addressing residual risk management in support of an application to surrender its mining leases.[cxliii]

Issues identified in this case study suggest areas for future research. One is understanding the cumulative impacts of the transitional provisions and pre-existing NUMAs as they apply to residual voids in flood plains. Second is further consideration of community and individual rights and infringement of these rights arising from lack of transparency in the regulatory framework and how these rights may influence the social licence of individual mines and the industry more broadly in Queensland. This would include further research to articulate the policy reasons for the enactment of the statutory exemption from disclosure of the financial assurance scheme contributions and its operation. Third is the meaning and scope of community consultation and its operation in the pre-existing NUMA process and post-mining risk management in eventually achieving relinquishment of the EA.