Blakefield South Mine SUBSIDENCE MANAGEMENT PLAN BLAKEFIELD SOUTH LONGWALL 7, 8 AND 9 SMP AREA 1. INTRODUCTION Bulga Underground Operations (BUO) are located approximately 12km south-west of Singleton, 1km north of Broke and 1.5km east of Bulga, in the upper Hunter Valley of NSW The Bulga Coal Complex (BCC) is managed by Bulga Coal Management Pty Limited (BCM) on behalf of the Bulga Joint Venture (BJV). The BJV is composed of the Bulga Underground Operations (BUO) and the Bulga Surface Operations (BSO). Each operation is managed by a separate business unit but serviced by a common coal handling and preparation plant (CHPP) and rail loading facility. BUO are operated by Bulga Underground Operations Pty Ltd (formerly Beltana Highwall Mining Pty Ltd). This Subsidence Management Plan (SMP) describes the framework for the management of the potential impacts of underground mining within proposed Blakefield South Longwalls 7, 8 and 9 (herein referred to as the SMP Area) (see Figure 1). The plan describes predicted subsidence parameters and outlines management measures to minimise associated risks to the environment, built features and public safety during mining. This plan has been prepared in accordance with the Guideline for Applications for Subsidence Management Approvals (2003) (herein referred to as the SMP Guidelines) issued by NSW Department of Mineral Resources (now known as Department of Trade and Investment, Regional Infrastructure and Services (DTIRIS)). The SMP Guidelines require specific management plans be developed to manage subsidence impacts which may have a high level of risk or consequence. Full details describing SMP Guideline requirements and where they have been addressed within this SMP have been provided in Section 4.6. This management plan includes, but is not limited to, the following: Identification of statutory requirements for subsidence management; Outline of mine design and subsidence predictions; Risk-based approach to the identification and management of potential subsidence impacts; Description of the management framework for subsidence; Description of stakeholder consultation processes undertaken during the development of the management framework; Subsidence Trigger Action Response Plan (TARP); Designated actions and responsibilities; Monitoring, reporting and notification requirements; and Revision requirements for the SMP. This SMP is a risked-based management plan as outlined within this document. Conservative approaches to subsidence prediction and impact assessment combined with substantial site experience (particularly in relation to Blakefield South Longwall (BSLW) 9), mine design and subsidence management and mitigation measures were considered to identify, minimise and appropriately manage potential residual risks. Page 1 of 44
Management plans will be actively updated during mining where required in line with progressive subsidence monitoring results confirming the subsidence predictions as part of the mine s continuous improvement process. 2. PURPOSE AND OBJECTIVES The purpose of this SMP is to provide an appropriate framework for the management of potential subsidence impacts from secondary extraction of BSLW7 - BSLW9 (herein referred to as the SMP Area) (see Figure 1). The document describes the mine s subsidence management framework including a range of related management plans, as detailed in Section 4. The document provides a summary of potential subsidence related impacts to natural features and items of surface infrastructure within the SMP Area, and outlines management measures to minimise associated environmental, infrastructure and public safety risks during mining. Further details pertaining to subsidence predictions are provided within the specialist subsidence assessments and the SMP Written Report. Objectives: The objectives of this SMP are to: 3. SCOPE 3.1 SMP Area Describe the BUO subsidence management framework designed to appropriately manage the environmental, infrastructure and public safety risks associated with secondary extraction within the SMP Area; Summarise potential subsidence impacts from longwall operations within the SMP Area; Summarise the risk-based approach used by BUO to develop the subsidence management framework; Describe community and stakeholder consultation processes; Describe proposed subsidence monitoring and mitigation measures; Describe the action and response plans in place for the above; and Fulfill the requirements of a Subsidence Management Plan in accordance with the SMP Guidelines. This plan has been prepared as part of an application for SMP approval to mitigate potential subsidence related risks associated with secondary extraction of coal from longwall panels within the SMP Area. In accordance with the requirements of the SMP Guidelines, the SMP Area (see Figure 1) has been calculated by combining the areas bound by the following limits: A 26.5 angle of draw line from the limit of proposed extraction; and The predicted limit of vertical subsidence, taken as the 20mm subsidence contour resulting from the extraction of the proposed longwalls. It is noted that BSLW9 and the majority of BSLW7 and BSLW8 have not been previously mined in the Whybrow Seam and are expected to primarily experience single-seam Page 2 of 44
subsidence conditions, with the exception of sections in the north - western ends of BSLW7 and BSLW8 as outlined further in this plan and the referenced subsidence specialist reports. In August 2012, an application to vary the approved SMP Application for BSLW1 6 was prepared and submitted to DTIRIS MRE for approval. This application for SMP variation was submitted to seek approval to remove BSLW6 from the approved BSLW1 6 SMP Area. The proposed BSLW7 and BSLW8 mining layout has been designed to extract the majority of the coal resource from the previously approved BSLW6. Page 3 of 44
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Blakefield South Mine 3.2 List of related Statutory SMP Plans (A0 Plans) The following SMP Plans (A0 plans) were submitted with the BSLW7 9 SMP Application and are listed below for reference where required: BSLW7 and BSLW8: BSLW9: General Location Plan. Plan 1 Existing and Proposed Seam Workings; Plan 2 Natural and Man Made Features; Plan 3 Geological and Seam Data (Blakefield Seam); Plan 4 Geological and Seam Data (Overlaying Whybrow Seam Underground Workings); Plan 5 Mining Titles and Land Ownership; Plan 6 North South Geological Section; Plan 6 West East Geological Section; Plan 7 Orthophoto Map; and SMP Approved Plan. Plan 1 Existing and Proposed Seam Workings; Plan 2 Natural and Man Made Features; Plan 3 Geological and Seam Data (Blakefield Seam); Plan 4 Geological and Seam Data (Overlaying and Underlying Underground Workings); Plan 5 Mining Titles and Land Ownership; Plan 6 West East Geological Section; Plan 7 Orthophoto Map; and SMP Approved Plan. 4. PLANNING 4.1 Planning Overview Bulga Underground Operations currently operate under a number of approvals including: Development Consent (DA 376-8-2003); Mining Leases (ML) 1547, 1494 and 1674; Exploration Licenses (EL) 5277, 5461, A450 and A447; Subsidence Management Plan Blakefield South Longwall 7, 8 and 9 SMP Area Page 5 of 44
Beltana (Bulga Underground Operations) Mining Operation Plan (MOP) accepted on 31 January 2008; and Clause 88(1) Approval to Longwall Mine BSLW1 6* within the Blakefield South Underground Mine. *The Clause 88(1) Approval will be varied for consistency with the amended mine layout (i.e. removal of BSLW6). A summary of relevant statutory approvals for the proposed mining areas at the BUO is provided in Sections 4.2 4.6. 4.2 Mining Leases Table 4.1 - Mining Leases Mining Lease Requirement Section Addressed ML1494, ML1547, ML1674 ML1494 ML1674 ML1547 ML1547 The lease holder shall prepare a Subsidence Management Plan prior to commencing any underground mining operations which will potentially lead to subsidence of the land surface. Subsidence Management Plans are to be prepared in accordance with the Guideline for Application for Subsidence Management Approvals. Operations must be carried out in a manner that ensures the safety of persons or stock in the vicinity of the operations. All drill holes shafts and excavations must be appropriately protected, to the satisfaction of the Director-General, to ensure that access to them by persons and stock is restricted. Abandoned shafts and excavations opened up or used by the lease holder must be filled in or otherwise rendered safe to a standard acceptable to the Director-General. Operations shall be conducted in such a manner as not to cause any danger to persons or stock and the lease holder shall provide and maintain adequate protection to the satisfaction of the Minister around each shaft or excavation opened up or used by the lease holder. The lease holder shall observe any instruction given or which may be given by the Minister with a view to minimising or preventing public inconvenience or damage to public or private property. This document. This document. Surface and Public Safety SMP. See also XCN SD ANN 0045 for standards relating to drilling, including post-drilling requirements. Surface and Public Safety SMP. Noted and acknowledged. ML1547 If required to do so by the Minister and within such time as may be stipulated by the Minister the lease holder shall carry out to the satisfaction of the Minister surveys of structures, buildings and pipelines on adjacent land holdings to determine the effect of operations on any such structures, buildings and pipelines. Noted and acknowledged. Page 6 of 44
Mining Lease Requirement Section Addressed ML1547 If so directed by the Minister the Lease holder shall rehabilitate to the satisfaction of the Minister any lands within the subject area which may have been disturbed by the lease holder. Noted and acknowledged. Surface and Public Safety SMP, Public Road Safety SMP, Telecommunication SMP, Powerline SMP. ML1547 ML1547 If so directed by the Minister the Leaseholder shall rehabilitate to the satisfaction of the Minister and within such time as may be allowed by the Minister any lands within the subject area which may have been disturbed by mining or prospecting operations whether such operations were or were not carried out by the Leaseholder. In the event of operations being conducted on the surface of any road, track or fire trail traversing the subject area or in the event of such operations causing damage to or interference with any such road, track or fire trail the lease holder, at his own expense, shall if directed to do so by the Minister provide to the satisfaction of the Minister an alternate road, track or fire trail in a position as required by the Minister and shall allow free and uninterrupted access along such alternate road, track or fire trail and if required to do so by the Minister, the lease holder shall upon completion of operations rehabilitate the surface of the original road, track or fire trail to a condition satisfactory to the Minister. Noted and acknowledged. Public Road Safety SMP, Surface and Public Safety SMP, Telecommunication SMP, Powerline SMP. Surface and Public Safety SMP, Public Road Safety SMP. ML1547 The lease holder shall provide and maintain a secure fence to the satisfaction of the Minister along the common boundary between the subject area and the Singleton Army Training Area. Surface and Public Safety SMP. ML1494 ML1674 Disturbed land must be rehabilitated to a sustainable/agreed end land use to the satisfaction of the Director-General. Section 12. ML1494 ML1494 Operations must not interfere with or impair the stability or efficiency of any transmission line, communication line, pipeline or any other utility on the lease area without the prior written approval of the Director-General and subject to any conditions he may stipulate. Operations must not affect any road unless in accordance with an accepted Mining Operations Plan or with the prior written approval of the Director-General and subject to any conditions he may stipulate. Powerlines SMP, Telecommunications SMP. Public Road Safety SMP. Page 7 of 44
Mining Lease Requirement Section Addressed ML1674 Prescribed Dam a) Notwithstanding any Mining Operations Plan, the lease holder must not mine within any part of the lease area which is within the notification area of the Bulga Old Tailings Dam without the prior written approval of the Minister and subject to any conditions stipulated. b) Where the lease holder desires to mine within the notification area he or she must: i) At least twelve (12) months before mining is to commence or such lesser time as the Minister may permit, notify the Minister of the desire to do so. A plan of the mining system to be implemented must accompany the notice; and ii) Provide such information as the Minister may direct. c) The Minister must not, except in the circumstances set out in sub-paragraph (ii), grant approval unless subparagraph (i) of this paragraph has been complied with. This sub-paragraph is complied with if: i) The Dams Safety Committee as constituted by Section 7 of the Dams Safety Act 1978 and the owner of the dam have been notified in writing of the desire to mine referred to in paragraph (b). ii) The notifications referred to in clause (a) are accompanied by a description or plan of the area to be mined. iii) The Director-General has complied with any reasonable request made by the Dams Safety Committee or the owner of the dam for further information in connection with the mining proposal. iv) The Dams Safety Committee has made its recommendations concerning the mining proposal or has informed the Minister in writing that it does not propose to make any such recommendations; and v) Where the Dams Safety Committee has made recommendations the approval is in terms that are: - In accordance with those recommendations; or - Where the Minister does not accept those recommendations or any of them in accordance with a determination under sub-paragraph (ii) of this paragraph. vi) Where the Minister does not accept the recommendations of the Dams Safety Committee or where the Dams Safety Committee has failed to make any recommendations and has not informed the Minister in writing that is does not propose to make any recommendations, the approval shall be in terms that are, in relation to matters dealing with the safety of the dam: - As determined by agreement between the Minister and the Minister administering the Dams Surface and Public Safety SMP. Page 8 of 44
Mining Lease Requirement Section Addressed Safety Act 1978; or - In the event of failure to reach such agreement as determined by the Premier. d) The Minister, on notice from the Dams Safety Committee, may at any time or times: i) Cancel any approval given where a notice pursuant to Section 18 of the Dams Safety Act 1978 is given. Suspend for a period of time, alter, omit from or add to any approval given or conditions imposed. 4.3 Development Consent Conditions Underground mining within the SMP Area is approved under planning consent DA-376-8- 2003 (as modified) issued by the NSW Department of Planning and Infrastructure (DP&I) under the Environmental Planning and Assessment (EP&A) Act 1979. The following conditions of consent apply to this plan: Table 4.2 DA 376-8-2003 (as modified) Condition Requirement Section Addressed Schedule 3, 2. Schedule 3, 4A Terms of Approval The Applicant shall carry out the development generally in accordance with the: a) DA 376-8-2003; b) EIS titled Bulga Coal Continued Underground Operations, volumes 1-5, dated July 2003; h) The conditions of this consent. Management Plans/Monitoring Programs Within 3 months of any modification to this consent, the Applicant shall review and if necessary revise all strategies/plans/programs required under this consent which are relevant to the modification, to the satisfaction of the Director-General. This document, Powerlines SMP, Public Road Safety SMP, Surface and Public Safety SMP, and Telecommunications SMP. Section 17. Schedule 4, 4. Before carrying out any underground mining operations that will potentially lead to subsidence of the land surface, the Applicant shall prepare a Subsidence Management Plan for those operations in accordance with the following Department of Industry and Investment (Minerals) documents (or the most current and updated versions of these documents): New Approval Process for Management of Coal Mining Subsidence Policy; and Guideline for Applications for Subsidence Management Approvals, to the satisfaction of the Director-General of DII (Minerals). This document. Page 9 of 44
Condition Requirement Section Addressed Schedule 4, 4A Schedule 5, 2. In fulfilling condition 4 above, the Applicant must: a) Prepare Subsidence Management Plans for longwall panels SB1 SB7 (now known as BSLW1-6 and BSLW9), and SB1 SB2 (now known as BSLW7 and BSLW8). These plans must take into account subsidence predictions arising from any case studies (i.e. empirical data) made available by the DII (Minerals) and be reviewed by an independent expert. NOTIFICATION OF LANDOWNERS If the results of monitoring required in Schedule 4 identify that impacts generated by the development are greater than the impact assessment criteria in schedule 4, except where this is predicted in the EA, and except where a negotiated agreement has been entered into in relation to that impact, then the Applicant shall notify the Director-General and the affected landowners and tenants (including tenants of mine owned properties) accordingly, and provide quarterly monitoring results to each of these parties until the results show that the development is complying with the criteria in schedule 4. This document, Powerlines SMP, Public Road Safety SMP, Surface and Public Safety SMP, Telecommunications SMP. Section 14. Private Property SMPs (to be prepared). 4.4 EPBC Approval Conditions (Requiring Commonwealth SMP) Significant portions of longwall panels BSLW7 and BSLW8 are located below surface lands owned by the Commonwealth of Australia and managed by the Australian Department of Defence. The environment and biodiversity of Commonwealth lands is protected and regulated under the Environmental Protection and Biodiversity Conservation Act (EPBC Act) 1999. A conditional approval was issued by the Federal Department of the Environment, Water, Heritage and the Arts (DEWHA) on 23 rd November 2004 to allow the undertaking of an action under the EPBC Act to extend underground mining operations at the Bulga Complex (EPBC Ref: 2002/773). Specifically, the approval is in effect for Sections 26 and 27A (Protection of the environment for actions involving Commonwealth land) of the EPBC Act. Condition 1 of the EPBC approval (November 2004) required the preparation of a plan for managing the impacts of subsidence on the environment on Commonwealth land, and provides specific requirements for the scope of the plan, including stakeholder consultation. Minor variations to the conditions of the EPBC approval were granted by DEWHA in November 2007 and November 2008 to extend timing for the submission of the Commonwealth SMP to accommodate timing of mine planning. The conditions of the EPBC approval (as varied) relating to the Commonwealth SMP are detailed in Table 4.2 below. Subsequently, the Blakefield South Longwalls 7 and 8 Commonwealth SMP (herein referred to as the Commonwealth SMP) was developed in consultation with the Department of Defence, and submitted to DEWHA in May 2009 to satisfy Condition 1 of the EPBC approval. The Commonwealth SMP identifies and manages potential subsidence related impacts associated with the extraction of coal from BSLW7 and BSLW8 under Commonwealth land managed by the Department of Defence, including (as a result of consultation) safety aspects to protect Department of Defence personnel. Approval of the Commonwealth SMP to satisfy condition 1 of the EPBC approval was received from DEWHA on 18 January 2010. Page 10 of 44
Separate to the surface land ownership by the Commonwealth, it is noted that the mineral rights to the coal resources located below the Commonwealth land are owned by the State of NSW. Mining Lease (ML) 1674 incorporates the approved Commonwealth SMP Area, as illustrated on Figure 2. It is also noted that the subsidence management and mitigation measures described within the approved Commonwealth SMP under the EPBC Act have also been referenced in the development of the BSLW7-9 Subsidence Management Plan (this document) and BSLW7-9 Surface and Public Safety Management Plan. These documents are required by the conditions of all NSW Mining Leases and have been prepared in accordance with the SMP Guidelines. These plans do not replace the Commonwealth SMP, but rather complement it and are consistent with it. Subsequently, the Commonwealth SMP remains a key active part of the subsidence management strategy for BSLW7 and BSLW8 dedicated specifically to the areas of Commonwealth land. Note: Conditions of the EPBC Approval relating to the Commonwealth SMP have not been necessary to be further considered within the BSLW7-9 Powerlines SMP, Telecommunications SMP or Public Road Safety SMP as these types of infrastructure items are not associated with/on Commonwealth land within BSLW7 and BSLW8. Table 4.3 - EPBC Conditional Approval EPBC Approval Condition Requirement Section Addressed 1 Prior to the commencement of the mine expansion, the person taking the action must submit for the Minister s approval a plan for managing the impacts of subsidence on the environment on Commonwealth land. The plan must include: a) A full description, including maps, of the area that may be impacted by mining activity, including areas of environmental and heritage sensitivity; b) Predictions of the expected extent of subsidence; c) A detailed outline of the potential environmental, heritage, land use and other impacts of subsidence; d) Proposals to minimise the impacts of surface subsidence, particularly in areas of environmental and heritage sensitivity; e) Measures for ground and surface water monitoring and management; f) Proposals for any necessary rehabilitation and repair of subsidence impacts; g) A process of stakeholder consultation; and h) A detailed and ongoing Subsidence Monitoring and Reporting Program. The plan must be submitted for the approval of the Minister within four years and six months of the date of this approval. The approved plan must be implemented. 2 Within one year of the commencement of mining activities within Commonwealth Lands, and at the completion of mining activities, the person undertaking the action must ensure that an independent audit of compliance with the Plan referred to in paragraph 1 (Commonwealth SMP) is conducted and a report issued to the Minister. The Commonwealth SMP (as approved by DEWHA January 2010), Note: The BSLW7-9 Subsidence Management Plan (this document) and the BSLW7-9 Surface and Public Safety SMP are also consistent with the Commonwealth SMP. Section 18 (Audits and Inspections) of this Subsidence Management Plan. Page 11 of 44
EPBC Approval Condition Requirement Section Addressed independent auditor must be approved by the Minister prior to the commencement of the audit. Audit criteria must be agreed to by the Minister and the audit report must address the criteria to the satisfaction of the Minister. 3 If the person taking the action wishes to carry out any activity otherwise than in accordance with the plan referred to in paragraph 1 (Commonwealth SMP), the person taking the action may submit for the Minister s approval a revised version of any such plan. If the Minister approves a revised plan, the plan must be implemented in place of the plan originally approved. 4 If the Minister believes that it is necessary or desirable for the better protection of the environment on Commonwealth land to do so, the Minister may request that the person taking the action make specified revisions to the plans approved pursuant to paragraph 1 (Commonwealth SMP) and submit the revised plan for the Minister s approval. The person taking the action must comply with any such request. The revised approved plan must be implemented. 5 On July 1 of each year following the commencement of mining activities on Commonwealth land, the General Manager of Bulga Coal Management Pty Ltd must provide a certificate that Bulga Coal Management Pty Ltd has complied with the conditions of this approval. Noted. Noted. Section 16 (Key Notifications) of this Subsidence Management Plan. Cover letter DEWHA would appreciate notification to the First Assistant Secretary, Approvals and Wildlife Division (Department of Environment and Heritage (DEH), now DEWHA) of the commencement of the action (underground mining in Commonwealth lands) and who the primary contact officer at the mine will be for the Department. Section 16 (Key Notifications) of this Subsidence Management Plan. 4.5 Blakefield South Longwall 1 6 SMP Approval* * this section will be revised accordingly following SMP Approval for BSLW7, 8 and 9, and has been included for completeness to demonstrate that the typical aspects within such approval conditions previously issued for the mine have been addressed within this plan. Any additional/specific information required will be included subsequently where required following SMP Approval. Table 4.4 - Blakefield South Longwall 1 6 SMP Approval Condition Requirement Section Addressed 14 The leaseholder must submit to the Director Mine Safety Operations for approval management plans for the following infrastructure that may be affected by subsidence. These plans must be developed in consultation with: Section 12 Public Road Safety SMP, Powerlines SMP, Telecommunications SMP, Surface and Page 12 of 44
Condition Requirement Section Addressed a) The owner/operators of the infrastructure; and Public Safety SMP. b) Any Government Agency with a regulatory role for the infrastructure. The leaseholder must not cause subsidence impacts prior to the management plans for the following infrastructure being approved: i. Electricity Transmission Lines; ii. Public Roads; iii. Water Pipelines;* iv. Telecommunications Cables; v. Any other infrastructure if required by the Director of Mine Safety Operations. *No water pipelines are located within the BSLW7 9 SMP Area. 15 The leaseholder must prepare and implement a public safety management plan to ensure public safety in any structures, houses and surface areas that may be affected by subsidence, to the satisfaction of the Director, Mine Safety Operations. The plan must include, but not be limited to: a) Identification of houses which are hazardous or could become hazardous due to subsidence impacts; b) Regular monitoring of areas or infrastructure/structures posing safety risks; c) Measures to prevent, mitigate and promptly remediate hazards and safety risks referred to in (a) and (b) above; Section 12. Surface and Public Safety SMP. Section 12. Private Property SMPs (to be prepared prior to undermining). Surface and Public Safety SMP, Public Road Safety SMP, Powerlines SMP, Telecommunications SMP. Surface and Public Safety SMP, Public Road Safety SMP, Powerlines SMP, Telecommunications SMP. d) Erection of warning signs Surface and Public Safety SMP. e) Entry restrictions Surface and Public Safety SMP. f) Backfilling of dangerous surface cracks. Surface and Public Safety SMP. g) Securing of unstable built structures or rock mass where required and appropriate; and Surface and Public Safety SMP, Powerlines SMP, Stevns Private Property SMP. Page 13 of 44
Condition Requirement Section Addressed h) Provision of timely notification of mining progress to the community and any other relevant stakeholders where management of public safety is required. 16 The Leaseholder must, within 24 hours of becoming aware of the occurrence, notify: (i) The Principal Subsidence Engineer; (ii) The Mine Subsidence Board; (iii) The Department of Water and Energy; (iv) The operators of all infrastructure covered by condition 14; and (v) Other relevant stakeholders Department of Water and Energy and Government Agency with a regulatory role if they request such notifications, of the following: (a) Any significant unpredicted and/or higher-thanpredicted subsidence and/or abnormalities in the development of subsidence; (b) Any exceedance of predicted impacts on groundwater resources and/or the natural environment that may have been caused (whether partly or wholly) by subsidence; (c) Any observed subsidence impacts adverse to the serviceability and/or safety of infrastructure and other built structures that may be affected by longwall mining; (d) Any significant subsidence-induced cracking and/or ground deformations observed in any surface areas within the SMP application area. Surface and Public Safety SMP, Powerlines SMP. Public Road Safety SMP, Powerlines SMP, Telecommunications SMP, Water Management Plan. 4.6 SMP Guideline Requirements This plan has been prepared in accordance with the SMP Guidelines issued in 2003 by the NSW Department of Mineral Resources (now known as DTIRIS). This plan forms part of an application to DTIRIS seeking SMP approval for the extraction of longwalls BSLW7, BSLW8 and BSLW9 in the Blakefield Seam. The SMP Guidelines require specific management plans be developed to manage subsidence impacts which may have a high level of risk or consequence. Table 4.5 demonstrates where this document addresses relevant requirements as outlined within the SMP Guidelines. Table 4.5 SMP Guidelines Requirements for the Preparation of a Subsidence Management Plan Section 7.2 Condition Requirement Section Where Addressed 1 The objectives of the SMP as defined by the applicant. Section 2 Page 14 of 44
Section 7.2 Condition Requirement Section Where Addressed 2 A summary of the leaseholder s subsidence management process, structure and organisation, with clearly defined responsibilities including, where appropriate, those of infrastructure owners, participating stakeholders and other third parties, and adequate training programs, resources and communication systems, etc. 3 The relevance and adequacy of the proposed mine layout, mining methods and sequences demonstrating that the identified management priorities have been adequately considered at the mine planning / design stage. 4 The relevance and adequacy of any proposed mitigation and remediation measures and/or any other management measures or procedures consistent with the identified management priorities. 5 The proposed program for the implementation of the above mitigation and remediation measures and/or any other management measures or procedures. 6 Estimated likelihood of success of the proposed mitigation and remediation measures and/or any other management measures or procedures. 7 The relevance and adequacy of the proposed community consultation programs, including the Subsidence Community Consultation Process (Section 7.4) if required. 8 The relevance and adequacy of the proposed monitoring, reporting and reviewing programs consistent with the identified management priorities as per Section 6.10. Where relevant, the principal elements of a monitoring program may include: 1) Monitoring of subsidence impacts on surface and sub-surface features; 2) Monitoring of the effectiveness of any mitigation and/or remedial measures; and 3) Monitoring of subsidence development. 9 Capacity of the proposed management system to detect early warning of any deviations from any defined outcomes on an ongoing basis and to correct any such deviations in a timely fashion. 10 The relevance and adequacy of any proposed contingency plans/emergency procedures in the event that any proposed management strategies/programs fail to control the subsidence impacts. Sections 5, 12, 19, 21 Section 6 Sections 11, 12 Sections 12, 13, 14 Sections 11, 12 Section 10Error! Reference source not found. Sections 13, 15, 17 Sections 12, 13, 14 Individual management plans detailed in section 12 including TARPs Sections 12,14 Individual management plans detailed in section 12 Page 15 of 44
Section 7.2 Condition Requirement Section Where Addressed including TARPs 11 Any proposed options, such as compensation, land acquisition, temporary relocation and other forms of agreement with the landowners in regard to likely compensable loss, if subsidence impacts cannot be reduced satisfactorily. 12 Any proposed measures for quality assurance of the management system. 13 A calculation of any additional security deposit required to reflect potential subsidence-related impacts. Section 12.5 Sections 13 16 Section 12.8 5. BLAKEFIELD SOUTH SUBSIDENCE MANAGEMENT FRAMEWORK The BSLW7 9 Subsidence Management Plan is a component of the BUO Environmental Management System (EMS) and incorporates the plans outlined in Table 5.1. Figure 2 shows the BSLW7 9 SMP Structure. Table 5.1 - Subsidence Management Plans Relevant to BSLW7-9 Management Plan BSLW7 - BSLW9 Surface and Public Safety SMP BSLW7 - BSLW9 Public Road Safety SMP BSLW7 - BSLW9 Powerlines SMP BSLW7 - BSLW9 Telecommunications SMP Private Property Subsidence Management Plans BSLW7-9 Subsidence Survey Monitoring Program Wollombi Brook and Monkey Place Creek Groundwater Contingency Plan Current Status Prepared for the SMP Area and submitted for approval with the BSLW7 9 SMP Application. Please refer to Section 12.4 for further detail. Prepared for the SMP Area and submitted for approval with the BSLW7 9 SMP Application. Please refer to Section 12.1 for further detail. Prepared for the SMP Area and submitted for approval with the BSLW7 9 SMP Application. Please refer to Section 12.2 for further detail. Prepared for the SMP Area and submitted for approval with the BSLW7 9 SMP Application. Please refer to Section 12.3 for further detail. To be prepared prior to commencement of the previous longwall panel (BSLW6), in consultation with and to the satisfaction of DTIRIS and relevant landowners. Please refer to Section 12.5 for further detail. To be prepared, prior to commencement of the previous longwall panel (BSLW6) in consultation with and to the satisfaction of DTIRIS. Please refer to Section 12.6 for further detail. The existing Wollombi Brook Groundwater Contingency Plan will be updated to include Monkey Place Creek prior to secondary extraction commencing. Please refer to Section 12.7 for further detail. Page 16 of 44
Management Plan Environmental Monitoring Program BUO Aboriginal and Cultural Heritage Management Plan Bulga Coal Complex Site Water Management Plan BUO Flora and Fauna Management Plan BUO Erosion and Sediment Control Plan Current Status Established and approved for BSLW1-6, to be updated for BSLW7-9 (primarily to add groundwater piezometers with respect to Monkey Place Creek alluvials) in consultation with DTIRIS and NOW prior to secondary extraction commencing within the BSLW7 and BSLW8 area. Approved in October 2004 and currently under review for the broader Bulga Optimisation Project (EIS) for completion in 2012. Will be revised and updated for BSLW7-9 prior to commencement of secondary extraction in consultation with relevant stakeholders. Approved in July 2008, revised and submitted to NSW Office of Water (NOW) in mid 2010 in accordance with statutory review requirements of BSLW1. Will be revised and updated for BSLW7-9 prior to commencement of secondary extraction in consultation with NOW. Approved September 2008, currently under review for the broader Bulga Optimisation Project (EIS) for completion in 2012. Will be revised and updated for BSLW7-9 prior to commencement of secondary extraction in consultation with the NSW Office of Environment and Heritage (OEH). Approved May 2008. The Plan was revised and approved July 2011. Page 17 of 44
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Blakefield South Mine 6. MINE PLANNING AND DESIGN 6.1 Mitigation and Minimisation of Subsidence in Mine Design With many years of previous mining experience within the lease (South Bulga and Beltana No. 1 mines) supported by further geological characterisation and ongoing mining for the Blakefield South Mining Area (BSLW1-5), Bulga Underground Operations has a substantial basis for mine planning and design to mitigate or minimise subsidence impacts. BUO has a demonstrated record of adopting a proactive approach to conservatively predicting and managing the impacts of mine subsidence, including recent multi-seam conditions within BSLW1 and BSLW2. Examples of mine design to reduce subsidence impacts include: Identification of key natural and built features within the SMP Area that may be sensitive to subsidence to ensure consideration in mine planning and design (including site databases of key environmentally sensitive areas); Designing the mine plan to minimise impact on natural and built features (e.g. Buffer/setback zones established for key alluvial areas of Wollombi Brook and Monkey Place Creek); Minimising mining under privately owned land and associated residences where practicable and establishing Private Property Subsidence Management Plans (PPSMPs) in consultation with affected land owners where required; Undertaking detailed specialist assessments for subsidence predictions and impact assessments (including detailed subsidence parameters and conservative worst case scenarios of greater than predicted subsidence) to assist in determining the level of potential impact such that appropriate management measures can be determined. This includes ground strains and curvatures for sensitive infrastructure (e.g. direct buried communications cables); Mitigation works where required to alleviate potential subsidence impacts (e.g. previous replacement of Telstra fibre optic in 2010 where required along Charlton Road ahead of mining in flexible conduit instead of direct buried); Ongoing consultation with key stakeholders to develop and refine plans of management for potential subsidence impact and communicate/notify of mining progress during extraction (e.g. periodic stakeholder email updates); and Implementing long-term subsidence and environmental monitoring programs, including a routine structured subsidence review processes (e.g. End of Panel Reports). There has been considerable consultation with stakeholders during the mine design process, including during the EIS (2003) and relevant modifications to the SMP (2007, 2010). This includes developing the mine plan, management and monitoring measures in consultation with government agencies. 6.2 Proposed Mine Geometry The proposed mine geometry and design is summarised below and described in further detail in MSEC (2012a, 2012b) and the BSLW7-9 SMP Written Report (Sections 3 and 5). The mine plans are illustrated in detail on the related SMP Plans (A0 statutory plans) also submitted with the SMP Application. Effective: 27/08/2012 Review: 27/08/2013 Page 19 of 44
Throughout the colliery holdings, the Blakefield Seam varies in thickness between 1.8m and 4.0m (Umwelt 2003). Bulga Underground Operations propose to extract a constant seam height of 3.6m from the Blakefield Seam in the BSLW7 and BSLW8 area (MSEC 2012a). Within BSLW9, Bulga Underground Operations plan to extract the full seam height which ranges between 2.0m and 2.85m (MSEC 2012b). The overall void widths of proposed longwall panels in the SMP Area, including headings (first workings), is 410m. The overall void lengths for BSLW7, BSLW8 and BSLW9 are 2510m, 2990m and 2065m respectively (MSEC 2012a, MSEC 2012b). A summary of the dimensions of the proposed longwalls is provided in Table 6.1. Table 6.1 Geometry of the Proposed Longwall Panels Longwall Overall Void Length (m) Overall Void Width including Headings (m) Solid Chain Pillar Width (m) BSLW7 2510 410 - BSLW8 2990 410 95 BSLW9 2065 410 - Table provided courtesy of MSEC 2012a and MSEC 2012b Overlying the Blakefield Seam, the lithology is comprised of several coal seams, of which only one coal seam (the Lower Whybrow Seam) has been economically mined in the surrounding area by the longwall retreat method (noting that only small sections in the northern aspect of BSLW7 and 8 have been previously mined, with the remaining majority of those panels and all of BSLW9 to experience single seam subsidence only (Whybrow Seam not previously mined). The remaining overlying lithology includes sedimentary rock layers such as sandstone, siltstone, claystone, shale, conglomerate and tuffaceous sediments (MSEC 2012b). 6.3 Mining Area and Depth of Cover The depth of cover associated with the SMP Area varies significantly within the BSLW7 and BSLW8 panels in contrast to the BSLW9 panel. Depth of cover within BSLW7 and BSLW8 varies between a minimum of 260m, above the finishing (northern) end of BSLW8, and a maximum of 510m, above the maingate of BSLW8 (MSEC 2012a). Depth of cover associated with BSLW9 varies between a minimum of 150m, towards the north-eastern end of the longwall, and a maximum of 200m, at the commencing (south-western) end of the longwall (MSEC 2012b). The proposed longwalls will be extracted below the previously extracted Whybrow Seam in the north-western section of BSLW7 and BSLW8 (only), with the majority of those panels and all of BSLW9 not previously mined. The interburden thickness between BSLW7 and BSLW8 and Whybrow Seam longwalls Why_E5 - Why_E7 varies between 90m and 100m. Characteristics of land above the longwall panels in the SMP Area are outlined separately below. BSLW7 and BSLW8: Proposed BSLW7 and BSLW8 extend beneath land predominantly owned by the Australian Defence Force (Singleton Army Training Base). Additionally within the BSLW7 and BSLW8 area, there is land owned by the BJV and six private property holders. Page 20 of 44
The surface of the land within the BSLW7 and BSLW8 area is steep and undulating with the main topographical feature of the area being the hill named Vere. The surface levels above BSLW7 and BSLW8 varies between a low point of approximately 95 metres AHD, and a high point of approximately 320 metres AHD. The natural surface gradients of the steep slopes typically vary between 1 in 3 and 1 in 2, with isolated areas having gradients up to 1 in 1. BSLW9: Proposed BSLW9 extends beneath land predominantly owned by the BJV, and to a lesser extent privately owned land. In addition, Charlton Road (owned by Singleton Shire Council) traverses the surface above BSLW9. The surface of the land within the BSLW9 area is generally flat to undulating, with the natural surface generally falling towards the drainage line which crosses directly above the proposed longwall. The surface levels directly above BSLW9 vary from a low point of approximately 80 metres AHD and a high point of approximately 130 metres AHD above the Southern Extension Dump. 6.4 Mining Schedule and Sequencing Blakefield South Underground Mine commenced longwall mining in July 2010. Mining in BSLW1 ceased in January 2011 as a result of a fire, mining in BSLW2 recommenced in May 2012. BSLW7 is scheduled for extraction in 2015. This will be followed by the extraction of BSLW8 and BSLW9 respectively. Within the SMP Area it is projected that main headings will be installed at 230m per week, gateroads at 320m per week and install roads at 180m per week. Longwall retreat is expected to progress at a rate of approximately 103m per week (180,000 tonnes per week). Table 6.2 Mining Schedule Longwall Development Extraction BSLW7 December 2013 2014 2015 BSLW8 April 2013 2014 2016 BSLW9 2014 2015 2017 7. SUBSIDENCE DEFINITIONS Subsidence, tilt and strain are the subsidence parameters normally used to define the extent of the surface movements that will occur as mining proceeds. Subsidence usually refers to vertical displacement of a point, but subsidence of the ground actually includes both vertical and horizontal displacements. These horizontal displacements in some cases, where the subsidence is small beyond the longwall goaf edges, can be greater than the vertical subsidence. Subsidence is usually expressed in units of millimetres (mm) (MSEC 2012a, MSEC 2012b). Vertical subsidence is the vertical distance (usually measured in millimetres) that the ground surface lowers as a result of mining, and depends on the depth of the coal seam, the thickness of the seam, the width of the extraction area and the characteristics of the overburden. Tilt is calculated as the change in subsidence between two points divided by the distance between those points (i.e. differential change in slope of the surface landform as a result of Page 21 of 44
mining). Tilt is usually expressed in millimetres per metre. A tilt of 1mm/m is equivalent to a change in grade of 0.1%, or 1 in 1000. Curvature is the second derivative of subsidence, or the rate of change of tilt, and is calculated as the change in tilt between two adjacent sections of the tilt profile divided by the average length of those sections. Curvature is usually expressed as the inverse of the Radius of Curvature with the units of 1/kilometres (km -1 ), but the value of curvature can be inverted, if required, to obtain the radius of curvature, which is usually expressed in kilometres (km) (MSEC 2012a). Strain results from horizontal movements in the strata. Strain is determined by calculating the horizontal change in length of a section of land surface and dividing this by the horizontal length of that section. The length of land (bay length) is also typically one twentieth of the depth of cover. If the section has been lengthened, the ground is in tension, referred to as tensile strain. If the section has been shortened, the ground is in compression, referred to as compressive strain. The unit adopted for strain is millimetres per metre (mm/m). The maximum strains coincide with the maximum curvature of the profile and hence the maximum tensile strains occur over the side of the panel whilst the maximum compressive strains occur towards the bottom of the subsidence profile (MSEC 2012a, MSEC 2012b). 8. SUBSIDENCE PREDICTIONS The maximum predicted conventional subsidence, after the extraction of BSLW7 and BSLW8 is expected to be 3.6m. This will occur above the northern end of BSLW7 and BSLW8 beneath Whybrow Longwall Why_E5 - Why_E7 (MSEC 2012a).The maximum predicted conventional subsidence resulting from the extraction of BSLW9 is 1.75m, which represents 65% of the Blakefield Seam (MSEC 2012b). The maximum predicted conventional curvatures for BSLW7 and BSLW8 are 1 km -1 hogging and sagging, which represent a minimum radius of curvature of 1 kilometre. The maximum curvatures occur where the maingate and tailgates of BSLW7 and BSLW8 mine beneath the Whybrow Seam longwalls (MSEC 2012a). Away from the northern ends of BSLW7 and BSLW8, the maximum predicted conventional curvatures for single-seam conditions are 0.3 km -1 hogging and sagging, which represent minimum radii of curvature of 3.3 kilometres. The maximum predicted conventional curvatures for BSLW9 are 2.5km -1 hogging and 3.0km -1 sagging, which represent minimum radii of curvature of 0.4 kilometres and 0.3 kilometres, respectively. The greatest hogging curvatures are expected to occur inside and immediately adjacent to the longwall maingate and tailgate sides. The greatest sagging curvatures are expected to occur near the centreline of the longwall (MSEC 2012b). The maximum predicted conventional tensile strain is expected to be 23mm/m and the maximum observed compressive strain is expected to be 19mm/m for BSLW7 and BSLW8 (MSEC 2012a). The maximum predicted conventional strains for BSLW9 are 25mm/m tensile and 30mm/m compressive (MSEC 2012b). Non conventional movements can also result from downslope movements where longwalls are extracted beneath steep slopes. In these cases, elevated tensile strains develop near the tops and along the sides of the steep slopes and elevated compressive strains develop near the bases of the steep slopes. The potential impacts resulting from down slope movements include tension cracks at the tops and along the sides of the steep slopes and compression ridges at the bottoms of the steep slopes (MSEC 2012a). Page 22 of 44
9. RISK ASSESSMENT 9.1 BSLW7 9 SMP Risk Assessment A risk assessment was conducted on 19 th May 2011 in order to review and identify the subsidence-related hazards that may affect the environment and community as a result of the extraction of the proposed longwalls BSLW7 9. The risk assessment reviewed the hazards that have been previously identified for the BSLW1 6 SMP Application (Umwelt 2008) and the Commonwealth SMP completed for BSLW7 and BSLW8 (Umwelt 2009). Additional risks have been identified and assessed through the review of known surface and sub-surface features within the SMP Area. The key deliverable will be an Environment and Community Risk Register for the project. This register will serve the purpose of: - Ensuring all considerable risks associated with the project are addressed in the SMP Application and its associated supplementary management plans; and - Provide evidence to the DTIRIS that BUO have made all reasonable efforts to consider the environment and community risks associated with the project. The SMP Risk Assessment has been completed by BUO to ensure that all considerable risks associated with the development and extraction of longwall panels within the SMP Area have been identified and adequately addressed. For each specific risk/hazard identified in the risk assessment, current controls that are in place are identified. Once this has been achieved the criteria outlined in the XCN Risk and Change Management Standard (XC RI STD 0001) is used to assign a risk ranking to each hazard using the 5 x 5 matrix. The risk ranking assigned to each risk/hazard was determined on the basis of group consensus. Where appropriate, additional controls were identified and recorded on the risk register. The outcome of the risk assessment forms the basis of this SMP Application. The risk assessment was facilitated by Dean Fletcher, Craig Bagnall and Adam Williams of GSS Environmental. The risk assessment was conducted in accordance with the following relevant guidelines and standards: AS/NZS ISO 31000:2009 Risk Management Principles and Guidelines; Guideline for Applications for Subsidence Management Approvals; MDG10 Risk Management Handbook for the Mining Industry; and XCN Risk and Change Management Standard (XC RI STD 0001). The SMP Risk Assessment identified twenty three risks. Of these risks, eleven risks were ranked as medium and twelve as low risks. There were no high ranked risks identified by the working group. Further detail associated with identified risks has been provided in the Risk Report (see Appendix 8 of the Written Report). Risks ranked as medium have been listed below: Public safety associated with surface cracking and stepping and rock/tree fall or soil slip; Catchment areas causing or exacerbating erosion and drainage pattern changes; The stability of cliff lines, rock pinnacles and steep slopes; The serviceability of major public utilities and/or amenities associated with Charlton Road, a privately owned quarry and Telstra owned underground fibre optic cable; Page 23 of 44