Longwall 43 Subsidence Monitoring Program

Transcription

1 Longwall 43 Subsidence Monitoring Program West Wallsend Colliery Page 1 of 32

2 Contents 1. Introduction Background Purpose Scope Relationship with Other Documents Consultation Statutory requirments Project Approval SMP Approval Subsidence Monitoring Natural Features Monitoring Ground Monitoring Steep Slope Monitoring Built features monitoring Steep Slope monitoring Process Technical Review Peer Review of Steep Slope Monitoring Modifications Review and Improvement External Reporting Review Accountabilities References Legislation West Wallsend Colliery External Appendix 1 Survey Monitoring Parameters Appendix 2 Survey Monitoring Marks and Procedures Appendix 3 Landscape Features Inspection Form Appendix 4 Subsidence Cracking Report Form Control and revision history Document information Revisions Page 2 of 32

3 1. INTRODUCTION 1.1 Background Oceanic Coal Australia Pty Limited (OCAL) manages and operates West Wallsend Colliery (WWC) on behalf of the Macquarie Coal Joint Venture (MCJV). OCAL is owned by Xstrata Coal. West Wallsend Colliery (WWC) is located approximately 25 kilometres southwest of Newcastle in the Lake Macquarie Government Area (refer to Figure 1). WWC has been granted Project Approval (PA 09_0203) for continued operations through the approval of the West Wallsend Colliery Continued Operations Project (WWCCOP) Environmental Assessment (EA), assessed under Part 3A of the Environmental Planning and Assessment Act 1979 (EP&A Act). Project Approval was granted on 25 January 2012 by the NSW Department of Planning and Infrastructure (DP&I) Director-General. The Project Approval allows for the continuation of mining operations at WWC and enables the consolidation of existing approvals for underground mining and infrastructure utilised for WWC. The WWCCOP assessed the coal reserves for WWC, the existing pit top and other related ancillary surface facilities, including the Mining Services Facility. WWC and the infrastructure above LW43 is shown in Figure 1. This Longwall 43 (LW43) Subsidence Monitoring Program has been prepared as a component of the WWC Longwall 42 & 43 Extraction Plan (WWC SD PLN 0101), in accordance with Condition 5(m), Schedule 3 of the Project Approval. The program also proposes monitoring to be undertaking in accordance with the DRE Subsidence Management Plan (SMP) approval condition. 1.2 Purpose The Subsidence Monitoring Program consists of survey and geotechnical monitoring to quantify subsidence parameters (i.e. vertical movements, ground tilts, strains, cracking, slope stability) (refer to Section 4.0) and a consolidated summary of environmental monitoring (refer to Section 4.1.3) to identify subsidence related impact to the environment and built features. The objectives of this subsidence monitoring program are to: provide data to assist with the management of the risks associated with subsidence; validate the subsidence predictions; analyse the relationship between the predicted and resulting subsidence effects and predicted and resulting impacts under the plan and any ensuing environmental and safety consequences; and inform the contingency plan and adaptive management process. Analysis of environmental monitoring data will be assessed in relation to their respective environmental management plans (refer to Section 1.4). 1.3 Scope The scope of this program is to detail the monitoring of subsidence on natural features and infrastructure from LW43 as shown in Figure 1. Page 3 of 32

4 1.4 Relationship with Other Documents This Subsidence Monitoring Program has been developed as a component of the WWC Longwall 42 & 43 Extraction Plan (WWC SD PLN 0101), and should be read in conjunction with the Extraction Plan/SMP. The monitoring program outlined in this document is a summary of the subsidence monitoring outlined in more detail in the following documents: WWC SD PLN 0050 Water Management Plan; WWC SD PLN 0052 Biodiversity Management Plan; WWC SD PLN 0057 Built Features Management Plan; WWC SD PLN 0058 Land Management Plan; WWC SD PLN 0059 Public Safety Management Plan; WWC SD PLN 0060 Subsidence Contingency Plan; and WWC SD PLN 0062 Aboriginal Cultural Heritage Management Plan. 1.5 Consultation WWC presented the proposed subsidence monitoring at a meeting with DRE and conducted a field visit of the monitoring locations for LW43 to consult on Subsidence Monitoring Program (SMP) in February and March 2014 so feedback could be received on the proposed subsidence monitoring. WWC also consulted with OEH on the LW43 Subsidence Monitoring Program provide a presentation on the proposed monitoring at meetings in February and March WWC consulted with the infrastructure owners on the subsidence monitoring proposed for the Gencom Tower, M1 Motorway and Services Easement when developing the LW43 & 43 SMP/EP in December Douglas Partners (DP) (2013) assessed the impacts of the predicted subsidence on steep slopes on provided recommendations for monitoring of the steep slopes in their report titled Geotechnical Assessment of Slope Stability Impacts Due to Mine Subsidence and of Steep Slopes Monitoring Programme Associated with Proposed Longwall Panels 42 & 43. Furthermore DP (2014) assessed the subsidence monitoring locations in their report titled Review subsidence monitoring locations Longwall Panel 43 - West Wallsend Colliery providing advice on the subsidence monitoring methods for steep slopes so these are consistent with their recommendations made in the DP report (2013), LW42 & 43 slope stability assessment. Page 4 of 32

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6 2. STATUTORY REQUIRMENTS 2.1 Project Approval The Project Approval for WWC was assessed under the Environmental Planning and Assessment Act 1979 (EP&A Act). Approval for WWCCOP was granted by the DP&I Director- General on 25 January The requirement for this Subsidence Monitoring Program arises from Condition 5(m), Schedule 3 of the WWC Project Approval which is shown in Table 1 below. Project Approval Condition Extraction Plan Table 1 Project Approval requirements 5) The Proponent shall prepare and implement an Extraction Plan for second workings on site to the satisfaction of the Director-General. Each extraction plan must: Section of this Document (m) include a subsidence monitoring program, which has been prepared in consultation with DRE and OEH, to: Entire document provide data to assist with the management of the risks associated with subsidence; validate the subsidence predictions; 4.0 analyse the relationship between the predicted and resulting subsidence effects and predicted and resulting impacts under the plan and any ensuing environmental consequences; and inform the contingency plan and adaptive management process SMP Approval This Subsidence Monitoring Program has been developed in accordance with DRE s SMP approval conditions and to meet the requirements of the WWC Scope of Works Steep Slope Monitoring Programme Western Mining Domain (WWC SD PLN 0096). In the event that changes to this document are required by DRE, the amended program will also be resubmitted to OEH & DP&I. Page 6 of 32

7 3. SUBSIDENCE MONITORING The proposed subsidence monitoring for LW43 is shown on plan Longwall 43 Subsidence Monitoring Plan KA The below sections describe the Subsidence Monitoring Program developed to monitor the predicted subsidence as described in Section Natural Features Monitoring Ground Monitoring WWC will monitor surface ground movements by undertaking a post mining Airborne Laser Scan (ALS) of LW43 within 2 months of completing extraction. Subsidence induced ground movement will be measured by comparing Airborne Laser Scanning (ALS) survey results pre mining and post mining. A pre mining ALS survey was conducted in July The ALS monitoring will provide a full coverage of ground movement for the longwall panel in addition to the proposed survey monitoring lines. Subsidence data (vertical) obtain from the ALS surveys will be accurate to within +/ m and will be calibrated using the existing subsidence monitoring line on the Great North Walk and Sugarloaf Range Road. Surveys using ALS methodology will minimise the environmental impacts in the Sugarloaf State Conservation Area (SCA) Steep Slope Monitoring DP (2013) concluded that the use of instrumental monitoring for slope stability is typically undertaken to monitor a well-defined, existing landslide or, to monitor a slope above critical infrastructure. The above being noted, the slope stability mechanisms associated with LW43 are relatively low risk as (DP 2013) and therefore are not well suited to instrumental monitoring. DP (2013) recommended that the current practice of weekly inspections and mapping are the most effective means of monitoring and managing the predicted subsidence for LW43. To monitor the potential for slope instability above LW43, weekly inspections of the surface affected subsidence zones (SASZ) will be conducted as further described in Appendix 1. These inspections will be undertaken by an engineering geologist and will focus on characterising and controlling hazards from subsidence cracking, rock & tree falls, VBMs, steep slope stability, and impacts on landscape features within the SASZ. The parameters to be monitored in the weekly inspections are further outlined in Appendix 1. These weekly inspections will also be conducted at the areas where VBMs may potentially occur and areas of risk of higher slope instability (refer to the Land Management Plan). Following the completion of LW43, a post mining inspection of the SASZ and landscape features will be undertaken using the Subsidence Cracking and Landscape Feature Inspection Forms (refer to Appendices 3 & 4) to record any further evidence of subsidence impacts. DP (2013) considered that the predicted locations of VBMs and their formation are expected to be a result of strata dilation and rotations of steep slope areas. As such DP (2014) have recommended conventional surveying of the slopes to monitor for relative movements at the survey monitoring lines D & E (to calculate strains) as show on plan KAO-145. Survey monitoring line G & H adjacent LW43 will be monitored pre and post mining as shown on plan KAO-145. To monitor the steep slope between LW41 and 43, WWC will extend the existing cross line on LW41 to the centre of the LW43 (refer to line C) as shown plan KAO Extension of this monitoring down the western slope is prevented from being monitored by a survey monitoring line as the registered aboriginal parties identified the Page 7 of 32

8 presence of archaeological sites (i.e. grinding groves, artefact scatters) and requested the area remain undisturbed as clearing may impact on the conservation of the these sites. Where accessible the survey marks will be installed at 10m bay lengths and surveyed (X, Y, Z) for position prior and post mining. The marks will be installed with reflector prisms so surveys of relative subsidence movements between the marks can be undertaken. To monitor of subsidence related strains from LW43 on steep slopes above landscape features DP (2014) recommended survey monitoring lines (F 1, F 2, F 3, & F 4 ) be installed perpendicular to the cliff line intersecting starting at about 2 m from the crest of the cliff and heading upslope at 10 m intervals for a length of 40 m were not constrained by other features. As such WWC will install the subsidence monitoring lines (F 1, F 2, F 3, & F 4 ) as shown in plan KAO-145 and monitor these pre and post mining. DP (2014) recommended strain gauges be installed perpendicular to the slope and at locations parallel to the survey lines above landscape features at 20 m bays or where 10 m bay, capable of transferring real time strain data. To monitor subsidence related strains WWC, will install strain gauges (at 20 m bays) set between the survey marks on lines F 2, F 3, & F 4 as shown on plan KAO-145 to record real time (10 min intervals) strain displacements (mm/m) on steep slopes above landscape features. WWC will continue to monitor the strain gauge adjacent the landscape features above LW42 (shown as line G on plan KAO-145) by recording real time subsidence related displacements during the mining of LW43. To monitoring the potential for slope instability in the vicinity of Sugarloaf Range Road, DP (2014) recommend real time strain gauges be installed parallel to the steep slope subsidence monitoring lines (C & D) and where practical these be installed between the crest of the slope and the road. As such WWC will install real time strain gauges perpendicular the subsidence monitoring line (B) on Sugarloaf Rang Road and parallel to subsidence monitoring lines (C & D) as shown on plan KA0-145 to record and transfer real time strain displacements (10 min intervals). The survey monitoring frequency and methods for the strain gauges are outlined in Appendix 1. The weekly inspections and the survey monitoring outlined above will continue until a peer review as outlined in Section 4.2 supports the modification or cessation of the monitoring. WWC will consult with the land manager (OEH) and consider any comments on the modifications or cessation of monitoring prior to applying to DRE to modify the LW43 Subsidence Monitoring Program. 3.2 Built features monitoring The built features above and adjacent LW43 include the Gencom Tower (CT1), Sugarloaf Range Road, Great North Walk, Services Easement and M1 Motorway as shown in Figure Gencom Towers and Power Pole Survey monitoring marks have been installed on the CT1 tower legs, ground marks and the adjacent power pole as shown on plan KAO-145. WWC will monitor the X, Y, Z, strains on the tower legs (CT1), adjacent ground marks and power pole prior, during and post mining as outlined in Appendix 1. Additionally, survey marks on the cross members of each tower will be monitored pre and post mining to monitor for tilting of the tower. Weekly visual surface inspections will also be undertaken for the same period as the survey monitoring. The inspections will be undertaken to identify potential surface cracking or other subsidence related impacts. Page 8 of 32

9 3.2.2 Great North Walk and Sugarloaf Range Road WWC will undertake monitoring of the survey marks and strain gauges located on the Great North Walk and Sugarloaf Range Road shown on plan KAO-145 for subsidence related ground movements (i.e. subsidence, strains & tilts) pre, during and post mining as outlined in Appendix 1. WWC has developed a Great North Walk Subsidence Management Plan and Land Management Plan in consultation with DPISCS/OEH for previously mined longwall panels and will implement the following monitoring measures: Pre, during and post mining photographic record of the access tracks condition, Surveys of the subsidence monitoring line pre, during and post mining as shown on plan KAO-145; and 24 hour contractor monitoring during subsidence affectation and repairs to subsidence cracking. The monitoring of these hazards will be undertaken in consultation with the DPISCS, DRE, OEH and the MSB. Consultation with DPISCS and OEH has indicated that this level of monitoring (i.e. 24 hr. visual monitoring during subsidence and pre, during and post surveys) is satisfactory M1 Motorway and Services Easement The services easement is located greater than 700 m away or greater than 6 times the depth of cover from LW43 s finish position and DGS (2013) predicted no subsidence will occur on the infrastructure. Surveys pre and post mining as outlined in Appendix 1 of the M1 Motorway and services easement survey monitoring lines (K & L) shown on plan KA0-140 will be undertaken to obtain subsidence data (i.e. X, Y, Z, strains & tilts) to confirm any far-field subsidence related movements from LW STEEP SLOPE MONITORING PROCESS WWC will implement the below process to monitor the potential for slope instability based on the slope stability assessment report and monitoring design undertaken by DP (2013). The process will use a technical reviewer to regularly review the monitoring data obtained from monitoring of steep slopes. 4.1 Technical Review WWC will engage a geotechnical engineer with experience in reviewing monitoring data for slope stability to undertake a weekly review of the survey monitoring data and the results of geotechnical inspections described in section The slope stability consultant will evaluate the results of the monitoring data by undertaking an analysis of the rate change in slope movements on the monitored sites (refer to plan KA0-145) to identify the potential for slope instability. The parameters monitored (refer to Appendix 1) during the weekly geotechnical inspections will also be incorporated into the technical review. The technical review will confirm if any further investigation or measures are to be implemented based on the assessment of the data. A summary of the results from the technical reviews will be provided to stakeholders in the fortnightly subsidence management status reports. In the event slope instability is identified from the technical review a report on the required monitoring measures will be provided to the stakeholders. Page 9 of 32

10 4.2 Peer Review of Steep Slope Monitoring Modifications If WWC proposes any modifications to the steep slope monitoring outlined in section 3.1.2, WWC will commission a peer review of these changes by a geotechnical engineer. This peer review will assess the requested changes based on the available monitoring data and make a recommendation, either agreeing or modify the requested changes. WWC will consult with the land manager (OEH) on any proposed changes to the Subsidence Monitoring Program. WWC will then submit to DRE for their approval an application to modify or cease the monitoring of steep slopes outlined in section Page 10 of 32

11 5. REVIEW AND IMPROVEMENT 5.1 External Reporting A summary of the subsidence monitoring results will be provided to stakeholders (OEH, DRE, DoP, infrastructure owners) in the WWC fortnightly and quarterly subsidence status reports. An Annual Report will be prepared in accordance with the Project Approval and Subsidence Management Plan approval conditions, documenting the subsidence monitoring results from the Subsidence Monitoring Program. Exceedance of any relevant subsidence predictions or performance criteria will be reported in accordance with the Project Approval to any relevant stakeholders. 5.2 Review In the event that subsidence predictions are revised, the affected management plans (e.g. built features plans) will be updated accordingly and submitted to relevant government agencies and placed on the WWC website ( Additionally, subsidence monitoring results received from built feature monitoring (e.g. services easement and F3 Freeway) will be assessed against trigger levels developed and reported accordingly. Ongoing monitoring and review on the performance and implementation of this document will be undertaken in accordance with WWC Environmental Management Strategy. In accordance with Condition 5 of Schedule 6, WWC shall review, and if necessary revise, the strategies, plans, and programs required under Project Approval to the satisfaction of the Director-General, within 3 months of the submission of: (a) (b) (c) (d) the submission of an annual review; the submission of an incident report; the submission of an audit report; and any modification to the conditions of this approval (unless the conditions require otherwise), The Subsidence Monitoring Program will reflect changes in requirements, technology, operational procedures and subsidence predictions. Updated versions of the approved plan will be made publicly available on the WWC website ( Page 11 of 32

12 6. ACCOUNTABILITIES Role WWC Operations Manager Environment and Community Manager WWC Subsidence Management Coordinator Accountabilities for this document Provide sufficient and timely resources for the effective implementation of this plan. Provide sufficient and timely resources for the effective implementation of this plan. Coordinate the subsidence monitoring requirements of the this Plan; Report monitoring and management measures to relevant stakeholders and update of subsidence predictions as required by this plan; Coordinate the reporting required by this plan WWC Mine Surveyor All employees and contractors Undertake subsidence monitoring requirements of the WWC Extraction Plan; Coordinate the surveying and internal reporting of monitoring results under this plan. Comply with all requirements of this plan. Report all subsidence impacts to their supervisor immediately. 7. REFERENCES 7.1 Legislation Environmental Planning and Assessment Act 1979 Mining Act 1992 Mine Subsidence Compensation Act West Wallsend Colliery WWC SD PLN 0101 Longwall 42 & 43 Extraction Plan and Subsidence Management Plan WWC SD FWK 0013 WWC Environmental Management Strategy WWC SD PLN 0050 Water Management Plan WWC SD PLN 0052 Biodiversity Management Plan WWC SD PLN 0057 Built Features Management Plan WWC SD PLN 0058 Land Management Plan WWC SD PLN 0059 Public Safety Management Plan WWC SD PLN 0060 Subsidence Contingency Plan WWC SD PLN 0062 Aboriginal Cultural Heritage Management Plan WWC SD PLN 0077 F3 Freeway Management Plan WWC SD PLN 0096 (Draft) Scope of Works Steep Slope Monitoring Program Western Mining Domain Page 12 of 32

13 WWC & Telstra Corporation Ltd Management Plan Longwall Mining Western Domain Adjacent to Telstra Network. WWC SD PLN Jemena, Caltex, Optus, Nextgen, Western Domain Subsidence Management Plan 7.3 External Aurecon, Gencom Tower Structural Assessment Tower CT1. August 2013 DGS, 2103, (WWD-012/17) Mine Subsidence Impact Assessment for Modifications to Longwalls 42 & 43. Douglas Partners, Report on Geotechnical Assessment of Slope Stability Impacts Due to Mine Subsidence and of Steep Slopes Monitoring Programme Associated with Proposed Longwall Panels 42 & 43, West Wallsend Colliery Killingworth, NSW. Douglas Partners, Review subsidence monitoring locations Longwall Panel 43 - West Wallsend Colliery. Robert Carr and Associates, Review of Landscape Features Above Proposed Longwall Panels 49 & 50, Sugarloaf State Conservation Area, West Wallsend Colliery. Page 13 of 32

14 8. APPENDIX 1 SURVEY MONITORING PARAMETERS Survey monitoring Marks A Gencom Tower CT1 and Power Pole Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Parameters 3D survey monitoring of marks. Layout of monitoring points shown on plan KA Survey marks on CT1 and power pole. Ground survey marks (star pickets) driven in to refusal. X, Y, Z (3D) pre, during and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. One per 100 m of extraction from start to 1450 m. A minimum 2 months after LW43 commences. Reporting of results to DRE/OEH within 48 hrs of completing the surveys. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring Marks B Sugarloaf Range Road Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Parameters 3D survey monitoring of marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 50 m intervals. X, Y, Z (3D) pre, during and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. Once per 100 m from 1800 m to 700 m (survey 250 m in front of face to 400 behind face). Then surveys will continue monthly and cease in consultation with DRE as outlined in section 4.2. Post mining a minimum 2 months after Page 14 of 32

15 LW43 face extends past the monitoring line. Recording and reporting of monitoring results Reporting of results to DRE/OEH within 48 hrs of completing the surveys. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring Marks C Centre to Panel Edge Cross Line Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Parameters 3D survey monitoring of marks. Layout of monitoring points shown on plan KA Ground survey marks (star pickets) driven in to refusal at accessible intervals. X, Y, Z (3D) pre and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Reporting of results to technical reviewer and DRE/OEH within 48 hrs of completing the surveys. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring line D - Steep Slope (DP reference D) Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & Parameters 3D survey of monitoring marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre and post mining on survey marks. During subsidence affectation surveys of relative movements to calculate strains between marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. Page 15 of 32

16 inspections Recording and reporting of monitoring results Once per week from chainage 1200 m to 800 m. Then survey are to continue monthly and cease in consultation with DRE as outlined in Section 4.2 Post mining a minimum 2 months after LW43 face extends past the monitoring line. Reporting of results to technical reviewer and DRE/OEH within 48 hrs of completing the survey. Summary of results reported in fortnightly subsidence status reports and annual report. Strain Gauge Sensors lines B, D & G Steep slope/sugarloaf Range Road Lines Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Parameters Strain gauge displacement sensors. Layout of strain gauges as shown on plan KA Strain gauges installed on survey marks at 10 m bays lengths. Displacements recorded in mm/m. Accurate to +/- 1 mm. Tensile displacement range 1200 mm. Installed prior to commencing LW43. Strains recorded at 10 minute intervals and hourly website data uploads. Strain gauge monitoring to continue until approved as outline in Section 4.2. Hourly upload of data to website and weekly technical review if triggers not reached (refer to plan KAO-145). Summary of results reported in fortnightly subsidence status reports and annual report. Page 16 of 32

17 Survey monitoring line E - Steep Slope (DP reference E) Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Parameters 3D survey of monitoring marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre and post mining on survey marks. During subsidence affectation surveys of relative movements to calculate strains between marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. Once per week from chainage 1100 m to 700. Then survey are to continue monthly and cease in consultation with DRE as outlined in Section 4.2 Post mining a minimum 2 months after LW43 face extends past the monitoring line. Reporting of results to technical reviewer and DRE/OEH within 48 hrs of completing the survey. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring lines F 1, F 2, F 3 & F 4 Steep slope/ cliff lines Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring Parameters 3D survey of monitoring marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Reporting of results to technical reviewer Page 17 of 32

18 results and DRE/OEH within 48 hrs of completing the survey. Summary of results reported in fortnightly subsidence status reports and annual report. Strain Gauge Sensors lines F 2, F 3 & F 4 Steep slope/cliff Lines Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Parameters Strain gauge displacement sensors. Layout of strain gauges as shown on plan KA Strain gauges installed on survey marks at 20 m bays lengths. Displacements recorded in mm/m. Accurate to +/- 1 mm. Tensile displacement range 1200 mm. Installed prior to commencing LW43. Strains recorded at 10 minute intervals and hourly website data uploads. Strain gauge monitoring to continue until approved as outline in Section 4.2. Hourly upload of data to website and weekly technical review if triggers not reached (refer to plan KAO-145). Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring line G - Steep Slope (DP reference E) Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Parameters 3D survey of monitoring marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre and post mining on survey marks. During subsidence affectation surveys of relative movements to calculate strains between marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 being 1400 m finish. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Page 18 of 32

19 Recording and reporting of monitoring results Reporting of results to technical reviewer and DRE/OEH within 48 hrs of completing the survey. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring line H - Steep Slope (DP reference E) Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Parameters 3D survey of monitoring marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre and post mining on survey marks. During subsidence affectation surveys of relative movements to calculate strains between marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior LW43 being 1400 m finish. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Reporting of results to technical reviewer and DRE/OEH within 48 hrs of completing the survey. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring line I Disused Forestry Track Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Parameters 3D survey monitoring of marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 50 m intervals. X, Y, Z (3D) pre, during and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Page 19 of 32

20 Recording and reporting of monitoring results Reporting of results to DRE/OEH within 48 hrs of completing the surveys. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring line J - Great North Walk Inspection regime Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Parameters 3D survey monitoring of marks. Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre, during and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 extraction. At chainage 600 m. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Reporting of results to DRE/OEH within 48 hrs of completing the surveys. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring line D Western Edge of Services Easement Parameters Inspection regime 3D survey of line D. Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 being 500m from finish. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Page 20 of 32

21 Recording and reporting of monitoring results Reporting of results to DRE/OEH within 48 hrs of completing the surveys. Summary of results reported in fortnightly subsidence status reports and annual report. Survey monitoring line E M1 Motorway Parameters Inspection regime 3D survey of line E. Layout of monitoring points Parameters to be measured Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Layout of monitoring points shown on plan KA Survey marks (star pickets) driven in to refusal at 10 m intervals. X, Y, Z (3D) pre and post mining on survey marks. Total station survey of marks as per survey standards and monitoring frequency (refer to Appendix 2). Prior to LW43 being 500m from finish. Post mining a minimum 2 months after LW43 face extends past the monitoring line. Reporting of results to DRE/OEH within 48 hrs of completing the surveys. Summary of results reported in fortnightly subsidence status reports and annual report. Inspections Subsidence Affected Surface Zones (SASZ) Inspection regime Layout of monitoring points Parameters to be measured Parameters 24hr monitoring of Sugarloaf Range Road during impact; Daily inspections of other access tracks during impact; Weekly visual inspection of surface and landscape features in SASZ by an engineering geologist. Visual inspection of surface, steep slopes and landscape features in SASZ. Parameters to be measured (refer to Appendices 3 & 4) include : - Landscape feature morphology (height, length, face slope) Landscape feature attributes (lithology, bedding, joints, cracking, and vegetation). Page 21 of 32

22 Monitoring methods and accuracy Timing & frequency of surveys & inspections Recording and reporting of monitoring results Subsidence cracking (length, width, depth, orientation, VBMs, rock or tree fall) Hazard identification (slope instability, VBMs, rock and tree falls) Identified possible instability (block/slip, likelihood of instability, modified risk rating AGS). Visual inspections recorded on landscape feature inspection and subsidence cracking forms (refer to Appendices 3 & 4). GPS mapping and photos (geo-referenced) by handheld GPS accurate to +/- 2 to 5m. Weekly inspections of SASZ. Recording of measured parameters once. Post mining inspection of SASZ and landscape features within 3 months of completing LW43. Review of tilt meter and strain gauge data prior to undertaking inspection. Modification or cessation of inspections in accordance with Section 5.0. Recorded on subsidence cracking and landscape feature inspection forms (refer to Appendices 3 & 4). Information then recorded in the WWC ArcGIS mapping system. Reporting of inspection to technical reviewer within 48 hours of completing inspection. A summary of the results provided to DRE/OEH in fortnightly subsidence management status reports and annual report. Page 22 of 32

23 9. APPENDIX 2 SURVEY MONITORING MARKS AND PROCEDURES Page 23 of 32

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26 10. APPENDIX 3 LANDSCAPE FEATURES INSPECTION FORM Longwall: Date: LW Face Position: Landscape Feature Morphology Landscape Feature Type Landscape Feature No. Description Height (m) Length (m) Face Slope ( ) Aspect ( ) Start (Coordinates) Finish (Coordinates) Landscape Feature Attributes Lithology Bedding Spacing Bedding Dip/ Strike Bedding Planarity/infill Joint Spacing Joint Dip/ Strike Page 26 of 32

27 Joint Planarity/infill Joint Spacing Vegetation Grass/Shrubs Vegetation Trees Photos Hazard Identification Potential instability Potential rock falls Potential tree falls Location of hazards in relation to public access points Mitigation works required (signage, demarcation, physical removal Public Safety comments Potential vertical block movement (VBM) Identified Possible Instability Block/slip size (WxLxH) (m) Likelihood of Instability Activation trigger Risk Rating AGS Subsidence Impacts Page 27 of 32

28 Crack Width (mm) Crack Depth (m) Crack Length (m) Crack Orientation ( 0 ) VBM step height (m) VBM width (m) Soil scarp height (m) Block fall area (LxH) (m) Block rollout length (m) Block numbers (m) Debris scree (Width x Length) (m) Tree fall (numbers) Start (Coordinates) Finish (Coordinates) Field Observations and Comments Page 28 of 32

29 Sketch Page 29 of 32

30 11. APPENDIX 4 SUBSIDENCE CRACKING REPORT FORM Instructions 1. This inspection form is to be used for general surface subsidence inspections. 2. A separate inspection form is to be used for inspections relating to cliff lines and steep slopes. Details Longwall Date Completed By Inspection Type (Circle one) SASZ Area - Weekly Access Tracks Daily Other Describe : Details of Cracking / Ponding Location (easting Length Width Depth Orientation General Description and northing) (m) (mm) (m) (degrees) Have cracks been mapped in GPS? Have photos been taken? Subsidence warning signs present? Page 30 of 32

31 Existing barrier or demarcation tape present on landscape features? Barrier tape checked? Have relevant stakeholders been informed? General Comments: Page 31 of 32

32 12. CONTROL AND REVISION HISTORY 12.1 Document information Property Approved by Document Owner Value Environment & Community Manager Subsidence Management Coordinator Effective Date 04/08/2014 Keywords Subsidence, monitoring, program, LW43 For a complete list of document properties, select View Properties from the document s context menu on the intranet Revisions Version Date reviewed Review team (consultation) Nature of the amendment 1 April 2014 E&C Manager Initial version 2 June 2014 E&C Manager Incorporated DRE comments. Page 32 of 32