8 CONTROL OF GEOTECHNICAL RISK 10 9 MONITOR AND …

Document Code: Pike River PHMP

Document Title: Ground or Strata Instability Principal Hazard Management Plan

Version No: 002 Approved Issue Date: 18/03/2020 Page 2 of 19 Document Owner: Kevin Pattinson Pike River Recovery Agency

TABLE OF CONTENTS

1 INTRODUCTION AND OBJECTIVES .......................................................................... 3 2 SCOPE ......................................................................................................................... 4 3 DEFINITIONS ............................................................................................................... 5 4 RISK ASSESSMENT ................................................................................................... 6 5 GEOLOGICAL AND GEOTECHNICAL DATABASE ......................................... ... .... 6 6 GEOTECHNICAL ASSESSMENT AND PRELIMIANRY DESIGN .............. ... .. ........ 7 7 DEFINITIONS AND ASSESSMENT OF GEOTECHNICAL HAZARDS AND RISK .... 8 8 CONTROL OF GEOTECHNICAL RISK ................................................. ................... 10 9 MONITOR AND ASSESS .................................................................... ..................... 11

9.1 Support Plans ................................................................................... ......................... 11 9.2 Monitor ....................................................................................... ............................... 12 9.3 TARPs ............................................................................... .. . ................................... 12 9.4 Installation and testing of Support Elements ............... .. .................................... 12 9.5 Inspections ................................................................. .. .. ......................................... 13 9.6 Hazard Mapping ....................................................... ................................................ 13 9.7 Strata Management Team meetings .................. ... .. ................................................ 13 9.8 Strata Control Incident Investigation ................ ....................................................... 14 9.9 Guidelines for Incident Investigation ........ .. ........................................................... 14 9.10 Incident statutory reporting requirements ................................................................ 14

10 SEISMIC ACTIVITY .................................... .............................................................. 15 11 PORTAL SLOPE ....................................... ................................................................ 15 12 ROLES AND RESPONSIBILITIES .. ......................................................................... 15

12.1 Site Senior Executive .......... ..... ................................................................................ 15 12.2 Mine Manager ............................................................................................................. 16 12.3 Geotechnical Engineer .... .. ...................................................................................... 16 12.4 Underviewer / Supervisor .......................................................................................... 16 12.5 Mine Workers ......... .................................................................................................... 16 12.6 Surveyor .......... .. .. ..................................................................................................... 16

13 PROCEDURES .......... ............................................................................................... 17 14 TRIGGER ACTION RESPONSE PLANS (TARPs) ................................................... 17 15 TRAINING AND COMPETENCY ............................................................................... 17 16 CORRECTIVE ACTION ............................................................................................. 17 17 DOCUMENT CONTROL ............................................................................................ 17 18 RECORDS .................................................................................................................. 18 19 REVIEW ..................................................................................................................... 18 20 AUDIT ........................................................................................................................ 18 21 APPENDICES ............................................................................................................ 18 Rele

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1 INTRODUCTION AND OBJECTIVES

It is the policy of Pike River Recovery Agency to reduce the risk to the workforce and machinery associated with strata control to as low as reasonably practicable (ALARP).

The Pike River Ground or Strata Instability Principal Hazard Management Plan (GSI-PHMP) has been developed specifically for the Pike River re-entry operation and enables Pike River Mine to:

Meet or exceed obligations under the:

a) Health and Safety at Work Act 2015b) Health and Safety at Work (Mining and Quarrying Operations) Regulations 2016

These objectives are achieved through:

• Development and implementation of a GSI-PHMP at Pike River Mine to control the risk ofStrata hazards to an acceptable level as low as reasonably practicable.

• Ensuring that strata control hazards are managed to the current standard in all parts of thedrift that are accessible.

• Ensuring that the strata management system is continually reviewed and improved.• Contributing to the development and maintenance of a safe working environment.• Utilizing predictive tools and standards to identify potentially hazardous areas and assess

associated risks. Such tools include data gathering and analysis, review of geotechnicaldata relating to the drift and geotechnical hazard assessment;

• Implementing appropriate remedial strata control interventions based on geological andgeotechnical assessments by a Geotechnical Engineer.

• Developing systems to ensure appropriate levels of inspection, hazard identification andstrata control management are implemented and recorded as part of underground shiftwork (i.e. geotechnical component to shift reports, geotechnical mapping andreconnaissance sheets, ground support guidelines for Mine Manager / Underviewer)

• Communicating known hazards to the workforce. Communication tools may include:o Hazard mapso Strata review reports as requiredo Monitoring results and auditso Design and implementation of systems to detect and control change (Trigger

Action Response Plans) based on findings of specific monitoring programmes,geotechnical data, the routine deformation monitoring database andrecommendations from relevant personnel as appropriate;

o Monthly Strata Management Team meetingo Permit to Recover – Geotechnical information provided in 100m intervals

• Design and implementation of procedures associated with strata control, includingStandard Operating Procedures (SOPs) for installation of strata support;

• Providing a management structure with adequate resources to comply with all aspects ofthe GSI-PHMP.

• Providing clear and unambiguous definitions of roles and responsibilities for individualsworking under the GSI-PHMP;

• Internal and external auditing to assess the effectiveness and degree of compliance withthe GSI-PHMP and assist in identifying improvement requirements;

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• Providing guidelines for investigation and review of strata failures or unpredicted strata behaviour for the purposes of continual refinement and improvement. This may include internal and external review and incident investigations;

• Providing guidelines for the retention and storage of critical documents and data including strata support design, modelling, monitoring information, exploration information and assessment, communication, and audit/review.

2 SCOPE The scope of this GSI-PHMP is specific to the Pike River Mine and relates to re-entry of the Pike drift and associated pit bottom development up to the rock fall located at or around chainage 2300m. This GSI-PHMP:

a) Applies to the area of drift out-bye the rock fall located at approximately 2300m b) Applies to all underground mine personnel, contractors and visitors who have duties under

the GSI-PHMP; c) Applies to all underground operations at Pike River Mine; d) Includes aspects of risk assessments, control strategies, management systems,

procedures, and guidelines associated with strata control at Pike River Mine; e) Forms the basis for training content and specifies requirements for training and

competency under the GSI-PHMP; f) Outlines resource requirements for the implementation and on-going maintenance of the

GSI-PHMP; g) Outlines the responsibilities and roles of individuals under the GSI-PHMP; h) Includes management systems and guidelines for design, monitoring and change to

underground openings and strata support in general; i) Details the Trigger Action Response Plan (TARP) to manage tunnel and ground support

deterioration in the drift. This GSI-PHMP has been developed to suit the requirements of the drift re-entry and addresses the following elements: Geological and geotechnical database Geotechnical assessment and design Pike River Drift Geotechnical Baseline Report (Re-Entry) Definition of geotechnical hazards and risk assessment Control geotechnical risk Monitor and assess effectiveness of controls Audit, review and improve Roles and responsibilities Assessment, competency, education and training Definitions

A process map highlighting the strata control process for Pike drift re-entry is provided below in Figure 1.

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Figure 1: Process map outlining strata control process for Pike River re-entry

3 DEFINITIONS

PRINCIPAL HAZARD A principal hazard is a hazard that has the potential to cause multiple fatalities.

HAZARD That which has the potential to cause harm

RISK The risk of injury or illness to a person arising out of a hazard.

EVENT Realisation of a hazard

GSI-PHMP Ground or Strata Instability Principal Hazard Management Plan

TARP Trigger Action Response Plan

INTERNAL AUDIT An audit conducted by mine personnel.

EXTERNAL AUDIT An audit in which the lead auditor has no operational ties to the mine.

HAZARD MAP A map which highlights strata related hazards in the Pike drift.

SUPPORT A structure or structural feature built into or installed around an underground excavation to maintain its stability.

RMR Rock Mass Rating

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SSE Senior Site Executive 4 RISK ASSESSMENT A risk assessment in relation to this GSI-PHMP was undertaken on 10th January 2019. The risk assessment was carried out in accordance with AS/NZS/ISO 31000:2010 and complied with MDG1010, using the current Pike River Recovery Agency Risk Ranking Matrix. A copy of the risk assessment is provided in Appendix A. The SSE should ensure that the records and revisions of the Ground and Strata Risk Assessment and records of any new risk assessment required are recorded and available on the PPRA Public Drive (MAKO) for the period of a minimum 7 years. The SSE shall ensure that strata related risks are identified, assessed and controlled for any new, changed or reviewed aspect of the strata management system including (but not limited to):

• new mine layout; • new support system and system/layout • new or changed mine management structure; • new or changed plant used or installed at the mine, which may affect ground control; • any major change in strata conditions • if a strata related incident occurs

The risk existing risk assessment notes that take 5 / JHA will be conducted each shift before bolting activities commence. Take 5s are not used by the PRRA and JHAs are not conducted each shift before bolting commences. Rather PRRA ensures that trained and skilled operators using fit for purpose equipment and following bolting SOPs ensure a safe working environment is maintained during bolting activities.

5 GEOLOGICAL AND GEOTECHNICAL DATABASE A geological and geotechnical database of the Pike drift has been developed by review of the following documents:

• Various URS face mapping reports to chainage 1974m • Various McConnel Dowell’s shift reports from the portal to 923m and from 2116m to 2318m • Monitoring and mapping data collected during development • Underground photographs (at the time of development) • Support supplier audit reports • URS as built construction report • Shotcrete strength, rock bolt encapsulation and pull test data collected by PRCL • Golder reports regarding re-entry considerations and ground support design for seal sites • Review of selected underground images post the mine explosion

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• Solid Energy inspections, monitoring and remediation from the portal up to the seal located at170m

A geotechnical assessment report summarising geotechnical aspects in relation to the drift is provided as Appendix B. This report is intended to provide a factual geotechnical baseline of drift conditions at the time they were recorded. It is important to note that there are many unknowns relating to the current geotechnical conditions in the drift given that most of its length it has not been entered by personnel following the November 2010 mine explosion and the potential for time dependent deterioration of the strata and ground support elements. Geotechnical factors to be considered during the re-entry process include:

• The single-entry nature of the drift • Prediction and variation of ground conditions within the drift • Actual & encountered conditions in the drift • Potential for deterioration of the drift and support elements • Areas of known or predicted structure and faulting • Potential impacts from recent regional earthquakes on drift stability • Areas of known or predicted poor quality ground • Areas of abnormal groundwater inflows • Areas of less than adequate installed support quality (i.e. bolt pattern, density,

encapsulation and surface restraint) • Areas of tunnel and / or support impacted by the explosion or heat • The adequacy of the initial support design and of the installed ground support • The ability to assess the adequacy of the installed ground support noting that shotcrete

may have be placed on 75% of the drift’s length • Potential for time dependent weathering and support deterioration • Areas of over dimension roadway

6 GEOTECHNICAL ASSESSMENT AND PRELIMIANRY DESIGN The design process will ensure strata hazards can be suitably characterised and controlled to acceptable levels during re-entry operations. Support design criteria shall be developed through documented geotechnical studies and may require the assistance of consultants as required. The design process will use industry accepted methods (empirical or otherwise) and be reviewed prior to implementation. Geotechnical assessment and design process will be undertaken in relation to the required ground support for re-entry. The output of the design work shall include a prediction of ground conditions and assessment of geotechnical domains (hazard maps). From this, a range of ground support plans can be developed and implemented onsite to pro-actively manage the predicted and encountered conditions during re-entry. Additional controls relating to the single-entry nature of the drift and mitigation of entrapment risk have also been evaluated and will be implemented as appropriate. A Single Entry PHMP has been developed and implemented by the PRRA.

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7 DEFINITIONS AND ASSESSMENT OF GEOTECHNICAL HAZARDS AND RISK The principal hazard recognised under the GSI-PHMP is uncontrolled movement of roof, rib or floor. The risks and control measures associated with this principal hazard and associated hazards have been considered in detail and form the basis of the Geotechnical Re-entry TARP (Appendix C). The key hazards associated with strata control at Pike River include: a) The presence of geological structure, which can have an adverse impact on conditions

through:

• weakening the immediate roof or rib rock mass quality • forming a weak boundary to which the roof or rib can easily fail • changing the immediate stress environment • creating a zone of clay gouge and fractured rock which may be more susceptible to

ongoing weathering Note:

• there is a transition zone between the metasedimentary gneiss and coal measures at the Hawera Fault

• a total of 10 faults were mapped in the gneiss section of tunnel

b) Areas of less than adequate support density or quality of installed support: Some areas, particularly about mapped faults appear to be under-supported for the rock conditions encountered, and some areas have been noted as having resin mixing (load transfer) issues during drift development particularly in areas of high groundwater inflow. It is not possible, based on the records, to determine if many of these areas have been adequately supported. c) Areas that have been affected by explosion or heat impacts: High temperatures from fires can cause significant material damage in tunnels and can lead to enhanced cracking in the immediate roof strata and spalling of the shotcrete and mesh degradation. It is not possible to rule out some degree of significant fire related damage to the roof (including falls of ground) in the weaker Coal Measure strata particularly the inbye end of the drift that would have been located the closest to the heat source and as such, would have experienced the highest temperatures.

d) Areas of deteriorated support elements: Black steel bolts were installed into the drift between 2006 and 2008. It has been almost 13 years since drift development commenced and 11 years since the drift was completed. Time dependant degradation (i.e. corrosion) of support elements and deterioration of shotcrete is possible. It appears very unlikely that the resin anchored bolts achieved full column encapsulation.

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e) Areas of poorer rock quality: Areas of poorer quality rock have been identified in the as-built construction records. Such areas are potentially more prone to degradation and as such, represent a higher relative risk than those areas in better condition. The blocky and sheared nature of the gneiss rock mass out-bye the Hawera Fault and potential for wedge failures on unfavourable orientated discontinuities. The variable and moderately to steeply dipping rock encountered in the coal measure section contained many weak carbonaceous and coaly bands. Areas of weathering, fretting, slabbing or guttering

f) Areas of over dimension roadway: The nominal design dimensions of the drift were 4.5 wide by 5.5m high. This was rarely achieved due to over break in the gneiss section and coal measure section of the tunnel. Areas of wider span (i.e. intersections and the PBIS) and higher ribs will require assessment. e) Roof or rib support loading: Resulting from ground stresses and stress variations and less than adequate support design or poor installation practices. Flattening or buckling of roof bolt plates, or bird caging of secondary support tendon tails are signs of ground support loading and / or poor bolt encapsulation. Such areas have increased potential for failure.

g) Water make:

Increased water make in the general roof or rib strata or whilst drilling roof or rib bolt holes for the installation of primary or secondary support can have an adverse impact on strata control through weakening the immediate roof or rib or alternatively reducing the integrity of the installed supports.

It was noted that groundwater inflows impacted resin mixing and subsequent load transfer during drift development. Water inflows would be expected to increase the potential for weathering in certain locations also and was noted to wash out clay infill during drift development. It is further noted that the Pike drift has consistently produced groundwater at the rate of approximately 6-8 litres/second (700,000l/day). Potential exists for groundwater impacts to rock mass stability, corrosion and floor trafficability.

h) Ground movement:

Limited deformation monitoring of the drift was conducted at Pike River. Convergence monitoring indicated high level of sidewall convergence in many locations in the Coal Measures section of tunnel. Automated tell tales will be used to measure potential roof movement during re-entry. Roof movement will be linked to the Geotechnical TARP. i) Areas of shotcrete concealing strata and steel support

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The extent of shotcrete application in the drift cannot be accurately determined. Up to 75% of the drift’s length may have been covered in shotcrete assuming class 4 rock and above received shotcrete to line the drift consistent with the design. Shotcrete lining makes inspection and mapping of the ground conditions and inspection and assessment of the installed steel support elements (rock bolts and mesh) very difficult and probably not practical at most locations (particularly across the tunnel crown).

j) Shallow depths of cover URS as-built report notes the error in surface height definition in steep, forested terrain resulting from aerial photogrammetry. As such, the Pike drift has been developed with a lower fresh rock head than originally designed. This factor was forwarded by URS to, in part, explain the lower rock mass quality encountered than was predicted. The more weathered rock mass in areas of shallow cover have the potential to provide modes of ground failure associated with blocky rockmass. The shallow cover also provides low confining stress to the blocky ground, coupled with potential for clay filled joints, enhances wedge type failures. 8 CONTROL OF GEOTECHNICAL RISK The main focus of this GSI-PHMP is to facilitate early recognition and timely control of strata control hazards by the re-entry team. It is recognised that not all strata related hazards are predictable and can be accurately defined in advance of re-entry due to the unknown condition of the drift beyond the current seal site (at 170m). The strata control process must remain responsive to changing ground conditions and variations observed in the drift to reduce the strata risks to an acceptable level. The premise for re-entry to the Pike drift is based around a staged and methodical process of inspection, assessment of hazards, assessment of stability, identification and implementation of remediation (if required) for incremental (short) lengths of the drift. This process is repeated up the drift. The geotechnical re entry TARP, adequate planning, practical and relevant training, effective communication, and inspection / compliance auditing form the key strategies to managing changing levels of geotechnical risk and ensuring appropriate controls are developed to minimise risk. The geotechnical re-entry TARP in this respect has been designed to make hazard definition clear, unambiguous, practical, achievable and not overly-technical. Strata hazards may not be limited to the list above, and strata hazards may have a close relationship to other hazards, e.g. gas make and ventilation. Consequently, strata hazards are managed under a Strata Management Plan; however, other management plans may also be relevant in the management of strata hazards and vice versa. Control of geotechnical risk during re-entry operations will be achieved through the following;

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• Development of a geotechnical hazard plan of the drift prior to re-entry using available information

• Inspection and assessment of the rock classification (where possible noting that shotcrete appears to cover a large area of the tunnel) assigned to the areas of the drift during actual construction and the assessment of the adequacy of the installed ground support

• A system to ensure the quality and quantity of the installed ground support materials and the integrity of installation. Note pull testing will be conducted on selected existing support elements to assist in determining the adequacy of installed support and any degradation that may have occurred.

• Rock bolt over-coring may be conducted for any specific areas of concern where practical to do so. It is recognised that pull testing fulfils many of the requirements of over-coring, namely; impacts on bolt pull out resistance caused by bolt corrosion, encapsulation and other resin performance / mixing issues.

• A system of inspection, hazard mapping, assessment, communication and response noting that provision is made on statutory shift reporting for inspection, mapping and assessment to occur.

• Development of support plans and safe work procedures for any remediation work noting that support guidelines have been developed for certain TARP levels which allow the site to develop their own support plans for review prior to implementation

• Having access to fit for purpose strata support equipment and hardware • Ensuring persons are competent, trained and follow procedures • Undertaking regular inspections and / or audit of strata support performance • A monitoring plan and then regular and routine roadway inspections, monitoring and

assessment (Note: automated tell tales – with visual analogue indicators - will be installed during re-entry)

• Ensuring roles and responsibilities under this document are communicated, understood and carried out

• Geotechnical re-entry TARP • Observation and reporting • Conducting regular Strata Management Team meetings • Identifying non-conformance and corrective actions and strata incident investigation • Authority to re-enter process

The control measures outlined above are explained in more detail in each of the relevant sections within this document. 9 MONITOR AND ASSESS 9.1 Support Plans

• All required support work identified by the Geotechnical Engineer during his/her inspections will be communicated via a Drift Support Plan.

• Guidelines for ground support design have been developed for site implementation for certain TARP responses and shall be reviewed & approved by the Geotechnical Engineer & Mine Manager prior to implementation

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• Any area requiring remedial support will be documented and provided to the Mine Manager who will arrange for the support work to be done

• A copy of the Pike River GSI-PHMP, Drift Support Plans, TARP and applicable hazard plans shall be available

• The Mine Manager shall ensure that all staff responsible for the re-supporting of roadways are trained and competent and familiar with the GSI-PHMP, Drift Support Plans, the Drift Strata TARP and strata management SOPs and related documents.

9.2 Monitor

A monitoring program shall be established to determine the support effectiveness, strata behaviour and excavation stability. Monitoring may include, but not be limited to:

• Visual inspections. • A system to ensure the quality and quantity of the installed ground support materials and

the integrity of installation (i.e. Non-destructive testing,pull testing and over coring to target specific area where practical).

• Geotechnical Monitoring comprising the installation of automatic tell-tales at locations outlined on the monitoring plan and as required during drift recovery

• Installation of prisms or other monitoring stations to measure tunnel deformation and surface slopes where required

9.3 TARPs The TARP system is recognised as the primary means of responding to changing geotechnical conditions and associated levels of geotechnical risk. The TARP outlines criteria (triggers) for several levels of response, corrective action and essential communications. A Geotechnical Re-entry TARP and slope instability TARP (Appendix C) has been developed to assist to re-entry process. The TARP includes requirements for verbal notifications, individual actions and recording of changes of levels of TARPs. This GSI_PHMP also requires the undertaking of strata control performance monitoring which forms part of the TARP. The adequacy and effectiveness of the TARPs will be reviewed at Strata Control Team meetings and adjusted as required to ensure all strata hazards are effectively managed. 9.4 Installation and testing of Support Elements The designed support shall be installed to established standard operating procedures and other safe working guidelines as outlined in this document. Operators shall constantly observe the ground conditions and monitoring effectiveness (e.g. drilling rates, water loss/gain, sooty backs, resin mixing etc.) and report any unusual conditions and action the TARP. The operators shall only use approved (by Mine Manager) installation equipment and support hardware as defined in the Support Rules.

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All testing of support elements shall be undertaken using fit for purpose and certified gear by persons competent and trained in its use. Operators should refer to the support plans for instruction prior to installing support. 9.5 Inspections Inspections shall be scheduled and conducted by the relevant personnel as specified in the Roles and Responsibilities section. Inspections will be performed prior to every shift and during the shift when there are people working within the drift, or at a minimum frequency of weekly, when there is no work being performed within the drift. The inspection regime will be:

• As per statutory inspection requirements • As required following identification of a deteriorated roadway strata area or following a

hazard being identified or incident being reported • As directed by the TARP • As indicated by the Permit to Recover process

All areas of the drift during re-entry shall be inspected by persons experienced, competent and trained in the identification and management of underground strata control hazards. 9.6 Hazard Mapping A URS geologist mapped most of the drift as it was advanced. The rock mass classification systems Q and RMR were used to determine the required ground support requirements in each segment of the tunnel. URS also completed an as-built construction report at the end of drift construction. Hazard mapping post the explosion was undertaken by a Solid Energy NZ Ltd Geotechnical Engineer who assessed the roadway conditions within the first 170m of drift out-bye the Mines Rescue seal (post explosion) in 2014. This was performed with best endeavours as most of the initial drift was shotcreted and therefore it was not possible to accurately map all hazards. A geotechnical hazard / risk map will be produced prior to re-entry. This map will be updated with geotechnical data collected during the staged re-entry and inspection process and may form part of reporting. 9.7 Strata Management Team meetings Strata Management team meetings will be conducted at least on a monthly basis and more frequently if required. The practice of regular, documented meetings will ensure the following:

• review the strata control conditions and hazards predicted & encountered in drift • assess compliance of re-entry practices against predicted conditions • provide for prediction and assessment of upcoming drift conditions

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• outline the status of continual improvement practices, and other matters relevant to managing the strata control risk during re-entry

9.8 Strata Control Incident Investigation Following the occurrence of an incident related to uncontrolled strata movement, general prior ties will be:

• removal of personnel from positions of potential harm • reduce or eliminate hazards sufficiently to enable safe recovery or treatment of injured

personnel • investigation, data collection and reporting • securing the roof and ribs • recovering equipment and resumption of re-entry

All incidents shall be reviewed at Strata Control Review Meetings 9.9 Guidelines for Incident Investigation Appropriately experienced personnel will be used in incident investigation. Consideration should be given to whether external opinion or other particular skills are also required. Records of all investigations, including analysis, conclusions, recommended actions and action completion will be maintained by the Geotechnical Engineer.

As relevant, strata control incident investigation may include;

• inspection of the incident site • photography and sketches to scale of the incident site • soliciting of verbal and written statements from personnel involved in the incident • soliciting of verbal and written statements from personnel associated with the incident (e.g.

process Managers, Supervisors and Operators) • compilation of a chronology of events • review of equipment and materials in use • assessment of compliance with the SMP • review of data • review of design • back analysis • revision or improvement of ground support design or operating practice • review and revision of the SMP

9.10 Incident statutory reporting requirements Strata related incidents will be reported to the relevant authorities by the Mine Manager as required by the appropriate regulations.

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10 SEISMIC ACTIVITY Both the surface and underground geotechnical TARPs include provision of suitable response in the event of an earthquake. If a seismic event is physically felt and / or reported at Pike River (in line with the TARP responses);

• Personnel within the mine will be withdrawn to a position of safety on the surface • The surface portal area will be visually assessed prior to operations commencing. • The access road and the White Knight Slip will also have a visual inspection by a mine

official prior to traffic passing the area. • If any significant changes or damage is detected on surface a geotechnical assessment

will be conducted by a Geotechnical Engineer. • A geotechnical engineer will inspect the drift with the Mine Manager authorising the restart

of re-entry operations.

11 PORTAL SLOPE The slope stability TARP (Appendix A) shall be used to manage and respond to changing levels of geotechnical slope instability risk. A visual inspection of the area above the portal (from ground level) will be undertaken by a statutory official prior to entry into the drift every working shift. Ongoing monitoring of the slope stability will be undertaken. Additional checks will be performed following any adverse weather events e.g. persistent rainfall or significant winds that may affect the integrity of the slope. 12 ROLES AND RESPONSIBILITIES The Pike River GSI-PHMP defines the specific responsibilities of key personnel in terms of the Pike River Strata Management Team. The team shall include, as a minimum, the following personnel:

• Mine Manager • Geotechnical Engineer • Deputy • Underviewer • Surveyor • Mine Workers

12.1 Site Senior Executive

• The SSE shall be responsible for ensuring that a site GSI-PHMP is developed and implemented at the operation consistent with relevant standards.

• The SSE shall appoint competent people to conduct their roles against the responsibilities defined in the GSI-PHMP, and document as part of the GSI-PHMP.

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• The SSE shall ensure adequate resources are available to develop, implement and maintain the GSI-PHMP.

12.2 Mine Manager

• Shall ensure that the requirements of the GSI-PHMP are complied with. • Arrange for remedial support work to be done • Ensure that required monitoring of support performance is carried out.

12.3 Geotechnical Engineer

• Provide best practice geotechnical input into the strata management process at Pike River Mine.

• Develop and maintain a hazard map • Facilitate the design of remedial support requirements as required. • Facilitate testing of roof and rib supports as required. • Participate in the review and auditing of the GSI-PHMP and TARPs. • Participate as part of the ATM/PTM process.

12.4 Underviewer / Supervisor

• Shall ensure compliance with all requirements of the Pike River GSI-PHMP. • Ensure that those people under their charge that have responsibilities under the GSI-

PHMP understand and perform those duties. • Manage the installation, reading and interpretation of monitoring equipment and ensure

findings are communicated to management in a timely manner. • Facilitate the installation of remedial support where required.

12.5 Mine Workers

• Comply with the GSI-PHMP and TARP. • Undertake daily checks of the roof and ribs of the drift when required to work within the

drift • Report verbally to the Underviewer/Deputy any deterioration in Strata and/or support

behaviour prior to or at the end of their shift. • Ensure that the appropriate re-support work is completed in accordance with the Support

Plan and TARP. 12.6 Surveyor

• Undertake survey and monitoring of portal slopes, drift and access road if required

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13 PROCEDURES Safe operating procedures and / or safe working guidelines shall be developed for all ground support installation. All OEM procedures relating to the safe operation of plant for the installation of support shall be available for operators. All operators installing support shall be trained in all relevant procedures for the task they are undertaking. 14 TRIGGER ACTION RESPONSE PLANS (TARPs) The following geotechnical TARPs have been developed for the drift re-entry:

• Drift Strata TARP • Slope Stability TARP

A copy of the TARPs is provided in Appendix C. 15 TRAINING AND COMPETENCY The mine shall develop a strata control workforce training module to cover the following areas:

• strata management plan and TARP(s) • site specific strata hazards and controls • ground support systems and installation procedures • other geotechnical information as requested by the Mine Manager or Geotechnical Engineer

16 CORRECTIVE ACTION The mine shall establish and maintain procedures for investigating non-conformance with the GSI-PHMP. The mine shall implement and record any changes in the documented procedures or GSI-PHMP resulting from corrective and preventive actions undertaken. 17 DOCUMENT CONTROL The mine shall establish and maintain procedures for controlling all documents to ensure that:

a) they can be readily located and be accessible;

b) they are periodically reviewed, revised as necessary and approved for adequacy by authorised personnel;

c) the current versions of relevant documents are available at all locations where operations

essential to the effective functioning of the plan are performed;

d) obsolete documents are promptly removed from all points of issue and points of use but must be kept for a period of at least seven years

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18 RECORDS The mine should establish and maintain procedures for the identification, maintenance and storage of all safety documentation. These documents should include training records and the results of audits and reviews. 19 REVIEW The Site Senior Executive must ensure the GIS-PHMP is reviewed for effectiveness:

• After each audit, if any non-conformances are identified. • Following an incident where strata control is identified as a contributing factor. • When the roadway support system has been found to be inadequate. • Following changes to the mine operating system which may affect the PHMP. • Following changes to the mine management structure which may affect the PHMP. • At least once every two years.

The Mine Operator must ensure that records of all reviews and revisions of the GIS-PHMP are kept for at least 7 years. 20 AUDIT The GIS-PHMP should be audited at least every three years by a person or persons independent of the operation and who were not responsible for developing and implementing the plan. 21 REFERENCES Several strata specific documents have been referenced in the GSIPHMP risk assessment as controls. These documents include: Geotechnical hazard map of drift Tell Tale monitoring plan – see hazard map for proposed installation location and inspection

procedure for monitoring plan Bolt testing procedures – see geotechnical drift inspection procedure Workforce strata training package SOPs for rock bolt installation:

o Megabolts o X grade bolts o CT rock bolts o Posimix bolts

Pike Drift Strata Support Plans 22 APPENDICES

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Appendix A: Ground Instability Risk Assessment Appendix B: Geotechnical Assessment Report Appendix C: Drift TARP and Slope Stability TARP for re-entry

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Documents

8 CONTROL OF GEOTECHNICAL RISK 10 9 MONITOR AND …