WA Guideline Refuge Chamber

8/11/2019 WA Guideline Refuge Chamber

1/21

Guideline

Refuge chambersin underground

metalliferousmines


2/21


3/21

ii Refuge chambers in underground metalliferous mines guideline Safety and Health Division, Department of Industry and Resources iii

Reference

The recommended reference for this publication is:Department of Industry and Resources, 2005, Refuge chambers inunderground metalliferous mines guideline: Safety and Health Division,Department of Industry and Resources, Western Australia, 32 pp.

ISBN 0 9757415 5 1

Department of Industry and Resources 2005

Except where the Copyright Act otherwise allows, reproduction in wholeor part of this publication will be permitted only with the prior writtenpermission of the Department of Industry and Resources. Applications forpermission should be addressed to the General Manager, Communicationsand Marketing Division.

Photographs on the cover (centre) and page 6 Allan Francis

This publication is also available in digital format (PDF) online atwww.doir.wa.gov.au/safety-pubs.

Further details of publications produced by the Safety and Health Divisioncan be obtained by contacting:

Safety and Health Division PublicationsDepartment of Industry and ResourcesMineral House100 Plain StreetEAST PERTH WA 6004

Telephone: +61 8 9222 3229Facsimile: +61 8 9325 2280Email: [email protected]

Contents

Foreword .........................................................................iv

1 Introduction .............................................................1

2 Risk statement .........................................................1

3 Nature of the hazard ................................................2

4 Location ...................................................................3

5 Capacity ...................................................................4

6 Adapting existing facilities .......................................5

7 Safety of location .....................................................5

8 Support of life ..........................................................7

9 Communication ......................................................10

10 Internal equipment ................................................11

11 Duration of independent services and power .........14

12 Personnel psychological issues .............................14

13 Electrical equipment..............................................16

14 Access and site layout ............................................17

15 Design and construction ........................................18

16 Maintenance ..........................................................20

17 Testing ...................................................................22

18 Further information ...............................................23

Appendix 1 Legislative requirements .........................25

Appendix 2 Hazards created by underground

ventilation practices .......................................................26

Appendix 3 Unplanned usage of refuge

chambers by visitor groups ............................................26

Appendix 4 Respirable air supplied from

compressors lubricated by hydrocarbons ......................27

Appendix 5 Potential independent

emergency power sources ..............................................28

Appendix 6 Usage control and

communication issues ....................................................30

Disclaimer

The information contained inthis publication is provided ingood faith and believed to bereliable and accurate at thetime of publication. However,the information is providedon the basis that the readerwill be solely responsible forassessing the information andits veracity and usefulness.

The State shall in no waybe liable, in negligence orhowsoever, for any loss

sustained or incurredby anyone relying on theinformation, even if suchinformation is or turns out tobe wrong, incomplete, out-of-date or misleading.

In this disclaimer:

Statemeans the State ofWestern Australia and includesevery Minister, agent, agency,department, statutory bodycorporate and instrumentalitythereof and each employee oragent of any of them.

Information includesinformation, data,representations, advice,statements and opinions,expressly or implied set out inthis publication.

Lossincludes loss, damage,liability, cost, expense, illnessand injury (including death).


4/21

iv Refuge chambers in underground metalliferous mines guideline Safety and Health Division, Department of Industry and Resources 1

Foreword

The Mines Safety and Inspection Act 1994established theMines Occupational Safety and Health Advisory Board(MOSHAB) comprising representatives of employers,employees, unions and government. MOSHAB had thefunction of advising and making recommendations to theMinister for State Development on occupational safety andhealth matters concerning the minerals industry in WesternAustralia.

MOSHAB was also empowered to prepare or recommendthe adoption of codes of practice, guidelines, standards,

specifications or other forms of guidance for the purposeof assisting employers, employees or manufacturers tomaintain appropriate standards of occupational safety andhealth in the minerals industry.

This guideline was developed through this consultativeprocess, and the views of all parties have been considered.It is issued by the Department of Industry and Resources(DoIR) under the Mines Safety and Inspection Act 1994, withendorsement by MOSHAB.

The Act

The Mines Safety and Inspection Act 1994sets objectivesto promote and improve occupational safety and healthstandards within the minerals industry.

The Act sets out broad duties, and is supported byregulations, together with non-statutory codes of practiceand guidelines.

Regulations

The Act is supported by regulations, which provide morespecific requirements for a range of activities. Like the Act,regulations are enforceable and breaches may result inprosecution, fines, or directions to cease operations andundertake remedial action.

Application

The provisions of this guideline apply to all undergroundmines as defined in section 4(1) of the Act.

1 Introduction

The purpose of this guideline is to provide guidance onthe safe use of appropriate refuge chamber facilities asa part of the response to hazards posed by irrespirableatmospheres underground. Typically, irrespirableatmospheres result from fires in the workings, but they canarise from other causes, including outbursts of gases suchas methane or hydrogen sulphide. The provision of refugechambers is central to any emergency preparedness plan,which in turn is fundamental to the duty of care.

The information presented here is largely based on a

series of risk assessments, carried out between 1997and 2003 at 13 underground mines in Western Australia,that addressed issues relating to the safe use of refugechambers. The assessments were undertaken by theindividual mining operations, independently of DoIR,and the associated documents remain confidential tothe respective companies. Other sources of informationinclude fire incident reports from national and internationalmining authorities, and guidance material produced byvarious bodies. Material specifications and constructionrecommendations comply with the appropriate AustralianStandard where applicable.

Note that this guideline may not include all factors relatingto underground refuge chambers and, in some respects,may not entirely address the individual requirements ofevery mine.

2 Risk statementAll mines to which this guideline applies should be ableto demonstrate that their emergency plans provide for thehazards associated with irrespirable atmospheres, andthat refuge chambers are being effectively managed. Riskmanagement is essential to prevent fatalities and injuries.It includes:

identifying the hazards

assessing the risks

making the changes necessary to eliminate the hazardor minimise the risk of injury or harm to health.

GUIDELINES

A guideline is anexplanatory documentthat provides moreinformation on therequirements oflegislation, detailsgood practice, andmay explain meansof compliance withstandards prescribedin the legislation. The

government, unions oremployer groups mayissue guidance material.

Compliance withguidelines is notmandatory but they couldhave legal standing ifit were demonstratedthat the guideline is theindustry norm.

WHO SHOULD USE

THIS GUIDELINE?

This guideline shouldbe used by anyoneresponsible for thesafety of personnelworking in undergroundmetalliferous mines.


5/21

2 Refuge chambers in underground metalliferous mines guideline Safety and Health Division, Department of Industry and Resources 3

3 Nature of the hazard

The hazards associated with an underground mineatmosphere becoming irrespirable due to contaminationfrom fire or other sources are well recognised in themetalliferous mining industry in Western Australia. Thetraining of miners has traditionally included varioustechniques of self-preservation using compressed air tocreate local breathable pockets in blind headings, venttubing, safety helmets, etc. Such techniques date fromthe period when compressed air was the universal energysource in underground mining, and timber for sleepers,support or shaft furnishings was the principal combustible

material.

The widespread use of diesel-powered and electricalequipment in underground mines means that compressedair reticulation systems have progressively disappeared,and the inventory of combustible materials has changed inboth nature and quantity. Most mines now have significantstocks of diesel fuel, hydraulic oil, rubber (as tyres),polyvinylchloride (as cable sheathing and piping), andresin-based composite materials used for various machineenclosures.

Nearly all underground fires reported in Western Australiaoccur on vehicles, and may result from:

high-temperature components on diesel prime moversproviding ignition sources for oil sprays from leakinghoses

sparking from abraded direct-current (DC) power leadsdamaging fuel lines

hot surfaces (i.e. > 350C) such as exhausts andturbochargers

binding brakes causing grease fires in wheel hubs andigniting tyres.

The initial problem confronting an underground worker in theevent of a fire is securing an immediate supply of breathableair. This is normally addressed by supplying everyone workingunderground with an oxygen-generating self-contained self-rescuer (SCSR). These devices come in various designs, andallow a person to travel from an endangered position to asafe haven. This presumes, of course, that such a safe havenexists in reasonable proximity to the endangered person.

The need for some form of refuge chamber inunderground metalliferous mines has long beenrecognised. Early types were frequently a redundantexcavation, which was blocked off to provide an enclosedspace where the atmosphere could be overpressuredusing compressed air sourced from the mine system.This basic model has evolved to incorporate morefunctionality and increased sophistication. The increasingprominence of diesel-powered trackless equipment anda greater awareness of the needs of the workforce haveprovided the impetus to develop self-contained chambersthat can be readily relocated to support the miningoperation as it progresses.

There is uncertainty about whether or not the function ofan underground refuge chamber can be extended to copewith a mine flooding or inrush situation the two worstdisasters in recent Western Australian mining history werecaused by such events. There appear to be two aspects tothis issue:

The design, construction and operation of such achamber would be akin to that of a small submarine.The potential demands on a submersible chamberwould require it to be purpose built because it would beimpractical to adapt an existing fire refuge chamber.

Flooding or inrush events develop so rapidly that thereis unlikely to be the opportunity for an undergroundworkforce to move to a designated place of safety beforebeing overwhelmed.

The Mines Safety and Inspection Regulations 1995 containa provision, reproduced in Appendix 1, that covers refuge

chambers.

4 Location

4.1 Distance from workplace

Refuge chambers should be sited near active workplaces,taking into account the needs of people working there andpotential hazards they face. It is recommended that themaximum distance separating a worker from a refugechamber be based on how far a person, in a reasonablestate of physical fitness, can travel at a moderate walking

KEY POINTS

LOCATION OF REFUGE

CHAMBERS

Site near activeworkplaces.

Consider needs ofworkers and potential

hazards they face. Maximum distance

between workplace andrefuge chamber shouldbe based on how far areasonably fit person cantravel at moderate walkingpace using 50% of SCSRnominal duration.

Maximum distance shouldbe no more than 750 m.


6/21


pace, using 50% of the nominal duration of the SCSR. If it isassumed that workers are equipped with SCSRs of nominal30-minute (minimum) duration, at a rate of 30 l/min, thenno-one should be expected to travel further than 750 m toreach safety.

This distance should be regarded as an absolute maximumbecause:

the duration of the SCSR can be adversely affected by thewearers state of agitation

physical difficulties may be encountered while travelling

smoke from a fire underground may be so thick that

crawling is the only feasible means of movement.It should be noted that crawling is necessarily slowerthan moderate walking, and should be allowed for whereapplicable. Also, the ventilation practices at a mine mayexacerbate the situation, as discussed in Appendix 2.

4.2 Nominal duration of SCSRs

The nominal duration of an SCSR is established at a specificrate of usage under standard conditions, as detailedin Australian Standard AS/NZS 1716:1994. However,experience and experiments suggest that the rate ofconsumption is much greater under emergency conditionsthan might be expected (e.g. Brnich et al., 1999; Jones etal., 2003). Arguments for more or better training, or both,and more frequent simulated emergencies have beenadvanced and have obvious value. However, the frequencyof genuine emergencies involving the use of SCSRs isrelatively low, and the financial impost of this training and

simulation is significant. The 50% of nominal durationreferred to in Section 4.1 attempts to build a realistic andpractical safety margin into the duration of SCSRs.

5 Capacity

The primary function of an underground refuge chamber isto provide a safe haven for people working in the immediatearea in the event of the atmosphere becoming irrespirable.

The chamber size should recognise that other personnelsuch as supervisors, surveyors, geologists and service

technicians may also need to use the facility. The number ofsuch people in the workings from time to time can require:

provision for a refuge capacity more than double thatdetermined from the size of the locally operatingcrew alone

or

implementation of a system to limit the number ofpersonnel in the area.

Appendix 3 suggests solutions to address the issue ofunplanned usage of refuge chambers by large visitorgroups.

6 Adapting existing facilities

The practice of designating a facility such as a lunchroomas a refuge chamber and equipping it for this purpose is acommon, and traditional, response to the need to providea safe haven. However, the size and general configurationof such a facility normally means that it can only besupported by the permanent services (ventilation, water andelectricity) of the mine. In this scenario, therefore, theseservices must be immune from any interruption. From bothtechnical and financial viewpoints, the equipping of such aresource with independent services is unlikely to be viable.

The lunchroom type of facility can be most useful wheneither performing as a fresh-air base or associated withone. In normal circumstances, a lunchroom is a semi-permanent installation in a mine, and while it may be

readily accessible from most areas, a maximum distance toall workplaces of 750 m is unlikely to be achievable.

7 Safety of location

7.1 Exposure to hazards

A refuge chamber is perceived as the ultimate place of safetyin an underground emergency. Its location should therefore beas secure from hazard as possible. Although the positioning ofa refuge chamber is strongly governed by its accessibility forpeople in need of its protection, any potential susceptibility of

KEY POINTS CAPACITY

Size should recognisepotential use by othermine personnel andvisitors

or

the mine shouldimplement a system tolimit number ofpersonnel in area

or

both of the above.

KEY POINTS SAFETY

OF LOCATION

Consider accessibilityandsusceptibility to hazards.

Assess susceptibilityof ground conditions toseismic activity and otherdisruptive influences.

Take into account theexisting water make ofthe mine and potentialfluid sources.

KEY POINTS

ADAPTING EXISTING

FACILITIES

The use of facilitiessuch as lunchrooms asrefuge chambers is notrecommended they are

better suited as fresh-airbases or associated withsuch bases.


7/21


8/21


survival of its occupants, in the most stress-free mannerpossible.

8.2 Stand-by

In this condition the refuge chamber stands ready forimmediate emergency use. No critical systems areactivated, but all can be immediately functional if required.

8.3 Externally supported

Respirable atmosphere

Ideally, the respirable atmosphere should be supplied via adedicated steel line from an oil-free source on the surface.The compressor supplying the air should be a genuine oil-free unit, providing fresh air. Where this is not possible, airdrawn from a lubricated piston, oil-injected screw or slidingvane type machine must pass through an air purificationsystem, including pressure regulator, valves and outlet,conforming to Australian Standard AS/NZS 1716:2003(respiratory protective devices). Problems specificallyrelated to hydrocarbon-lubricated units are outlined inAppendix 4.

Potable water

If a piped supply of drinking water is installed then it shouldbe brought from the surface to a refuge chamber via anindependent, dedicated non-metallic pipe installed in aborehole.

Alternative air and water supply routes

If breathing air and drinking water cannot be fed to a refugechamber through a dedicated borehole, and instead are directedthrough the normal mine access routes, only steel piping mustbe used. Note that if the steel pipelines pass near a fire thenthey will get hot, as will anything passing through them.

Where available, a mine-wide compressed air reticulationsystem using steel piping can supply breathing air for arefuge chamber. The air delivered to the chamber mustbe filtered to Australian Standard AS/NZS 1716:2003specifications.

Entry of breathing air into the refuge chamber should besubject to noise suppression measures, and the rate offlow set to maintain a small overpressure in the chamber,relative to the external atmosphere. Pressure ventingsystems matched to the maximum design airflow shouldbe fitted and have immediate self-sealing capability if theexternal atmospheric pressure exceeds the pressure in thechamber.

8.4 Stand-alone

Total disconnection from external services is possibleduring an emergency, and measures must be taken to

provide full, independent life support for the occupants ofa refuge chamber. This is probably the pivotal differencebetween the traditional refuge chamber model and thatdefined by the needs of current underground mining.

The basic requirements under these fully isolatedcircumstances are:

a respirable atmosphere

an electrical power source to maintain support systems

a supply of drinking water

the capability to maintain atmospheric conditions insidethe chamber securely below heatstroke-inducing levels.

Respirable atmosphere

A respirable atmosphere can be provided by replenishingoxygen and scrubbing the atmosphere inside the chamberof excess carbon dioxide (CO

2) and carbon monoxide (CO).

Oxygen can be replenished by adding normal air, as longas the source remains available, and excess CO2and CO

can be removed. There is a risk that the air supply willbe severed and, consequently, an independent means ofsupply must be provided. Medical-grade oxygen in bottles,sufficient for a full complement of occupants for 36 hours,should sustain a consumption rate of 0.5 litres per minuteper person. The provision of backup supplies from oxygencandles is strongly recommended.

Power supply

Atmospheric scrubber units, lighting, air conditioningand electronic control systems require a secure supply

KEY POINTS

EXTERNALLY

SUPPORTED CHAMBERS

Respirable atmosphereshould be supplied via adedicated steel line froman oil-free source on thesurface.

Water should be broughtin via an independent,dedicated non-metallicpipe installed in aborehole.

For breathing air anddrinking water directedthrough normal mineaccess routes, use steelpiping.

The entry of breathing airinto the chamber shouldbe subject to noisesuppression measures.Set flow rate to maintaina small overpressure.

KEY POINTS

STAND-ALONE

CHAMBERS

Stand-alone chambersmust provide full,independent life supportfor the occupants, with

total disconnectionfrom external servicespossible.

Basic requirementsunder fully isolatedcircumstances are arespirable atmosphere,electrical power source,supply of drinking waterand capability to maintainatmospheric conditions.


9/21


of electricity. In normal circumstances, power can beprovided from the mine electrical system. However, it mustbe assumed that this source can fail and backup must beavailable. Potential independent emergency power sourcesare discussed in Appendix 5.

Potable water

Drinking water is frequently available in Western Australianunderground operations from dedicated reticulationsystems. Like any pipework system, these can beinterrupted in a fire event. It is recommended that sufficientpotable water be maintained at the refuge chamber to

adequately supply a full complement of potential occupantsfor 36 hours.

Environmental control

Simulated emergencies, in which a full complement ofpeople has occupied a refuge chamber for a significantperiod, indicate that humidity and temperature can increasevery rapidly to potentially heatstroke-inducing levels.Refrigerative air conditioning is strongly recommendedfor both externally supported and stand-alone refugechambers to counter this potentially serious problem.Inevitably, this will place a heavy demand on the stand-alone power supply, but there are systems available thatcan cope, and at an acceptable cost.

9 Communication

For many years the simple provision of a secure telephonelink to a control centre or other manned facility has beenregarded as fulfilling the need for communication in anunderground refuge chamber. This arrangement has stoodthe test of time, particularly when refuge chambers andrelated facilities were very basic. However, if the link iscompromised or the control centre is not manned 24 hoursa day, there is the potential for people to abandon refugechambers if they do not have communication updating themon the progress of their rescue.

There have been significant developments in undergroundcommunication systems in the past decade. Leaky feedersystems based on a special type of coaxial cable can

be used to provide radio coverage inside buildings andtunnels. Personal emergency devices (PED) provide anultra-low frequency, through-the-earth, paging system.Hardwired systems have also become very capable in termsof carrying high-quality digital information. In the future,sophisticated high-quality video and audio contacts betweena refuge chamber and surface control centre could alleviateanxiety in the occupants and assist in management of theemergency.

Management can also use communication systems to helpcontrol inappropriate use of refuge chambers. There aresystems to alert a control room operator or supervisorstation to personnel entering a refuge chamber, and

initiate steps to establish the reason. Usage controland communication issues are discussed more fully inAppendix 6.

10 Internal equipment

10.1 Considerations

Although it may appear desirable to equip a refuge chamberwith as many internal features as the budget permits, itshould be borne in mind that:

internal space is commonly significantly restricted in theunderground environment

the primary purpose of the chamber is the preservationof human life, so the genuine functionality of everycomponent of the system should be closely examined

and its inclusion justified.

10.2 Air and water

After a respirable atmosphere, drinking water is the nextmost important provision for an underground refugechamber. Various regulators have specified, commonly inlegislation, that a supply of food be maintained, sufficientto provide for a set number of people for a specificperiod. However, in the context of an undergroundemergency in a Western Australian mine, hunger isunlikely to be an issue. People can survive for longperiods without food but the human body is ill-equippedto cope with dehydration, which affects decision making

KEY POINTS

COMMUNICATION

Telephone linkage isnot always adequatefor communication, aspeople may abandon achamber if the link iscompromised.

Alternati ve forms of radiocoverage include leakyfeeder systems, personalemergency devices andhardwired systems.

Communication systemscan be used to controlinappropriate use of achamber.

KEY POINTS

INTERNAL EQUIPMENT

Consider the restrictionof internal space andfunctionality whenassessing the inclusionof equipment.

Desirable equipmentincludes a first aid kit,oxy-viva equipment, toiletand table, as well assmall items to increasethe safety and comfort ofoccupants.


10/21


and reduces coordination essential skills for survivalin an emergency situation.

10.3 First aid

A comprehensive first aid kit is an obvious and necessaryprovision in a refuge chamber. It should include suppliesadequate to deal with multiple casualties. The equipmentlist should include blankets to assist in shock management,and a stretcher. Spine boards are recommended rather thanconventional stretchers, and underground mine staff shouldbe trained in their proper use.

10.4 Oxy-viva equipment

Oxy-viva equipment can provide the benefits ofresuscitation, suction and oxygen therapy in one compactunit, operating from a 400 l oxygen cylinder. Its availabilitywould greatly assist people suffering from respiratory orrelated difficulties. The provision of oxy-viva equipmentis recommended subject to the condition that potentialoccupants of the chamber know how to use it correctly.

10.5 Toilet

Toilet facilities are necessary but need not be overlysophisticated. A self-contained portable unit of adequatecapacity is sufficient, bearing in mind the potential numberof occupants and a stay of up to 36 hours in the chamber.Technology exists to provide fully private and functionaltoilet facilities but this significantly constrains internalspace, greatly complicates the technical arrangements ofthe chamber, and increases its cost for little return. Issuesof privacy should take second place to effective operation ofthe refuge chamber.

10.6 Table

A table has been identified as a desirable feature insidea refuge chamber, based on a perceived and probablyjustifiable requirement for the occupants to engage in time-consuming and attention-distracting activities such as cardplaying. The imperative of efficient use of internal spaceprecludes the provision of a permanently erected table.However, a camping-type table can be effective and is easilyset up or d ismantled as required.

10.7 Eye-wash station

Provision of facilities such as eye-wash stations in thechamber should be considered in the context of spacerequirement versus functionality. An eye-wash stationcould be provided outside the chamber for use prior toentry without introducing another space-limiting deviceinside. Being external, it would also be available for non-emergency situations. If conditions outside the chamberpreclude the short-term use of an eye-wash station whenoccupants are assembling, then it is a minor matter toinclude disposable eye-wash in the first aid kit inside thechamber.

10.8 Other equipment

Other items that should be considered are:

dry chemical powder (DCP) fire extinguisher orextinguishers

pens and paper

pack of playing cards

torch and batteries

provision for storage of equipment.

Facilities such as eye-washstations should be consideredcarefully, and are probablybetter provided outside thechamber


11/21


12/21


13 Electrical equipment

All electrical installations must conform to AustralianStandard AS/NZS 3000:2000. Due to the uncertainty ofconditions in any particular location underground, allexternal terminations must have an ingress protection (IP)rating of IP56.

Direct current (DC) extra low voltage (ELV) refers to systemsoperating at 50V and less. All ELV circuitry must conform tothe appropriate provisions of Australian Standard AS/NZS3000:2000.

All circuit breakers used on the DC side must be selected

on the basis of DC current ratings. Where alternate current(AC) ratings are provided, the AC rating must be multipliedby a de-rating factor of 0.6 for DC use.

Protective devices are selected from the following, inaccordance with the indicated standard:

fuses Australian Standard AS/NZS 1775:1984

combination fuse switch units incorporating highrupturing capacity (HRC) fuses Australian StandardAS/NZS 1775:1984

miniature circuit breakers (MCB) Australian StandardAS/NZS 3111:1994

moulded case circuit breakers (MCCB) AustralianStandard AS/NZS 2184:1985.

Battery enclosures must conform to AustralianStandard AS/NZS 2676.1:1992. Battery terminationsmust conform to Australian Standard AS/NZS

3011.1:1992.

Although not specified in the Mines Safety and InspectionRegulations 1995, DoIRs view on the regulation of electricityis that the provision of 240V AC general power outlets (GPOs)should be strictly controlled in the underground environment.GPOs should only be installed where necessary, such as inunderground workshops. The presence of a GPO in a refugechamber, particularly if in an emergency situation it can drawpower from the stand-alone system, has the potential toprematurely exhaust the available power.

The use of braided or armoured cable is encouraged byDoIR when wiring underground installations. It is accepted

that there is a cost penalty but it is not great and the safetybenefits are significant.

14 Access and site layout

14.1 Vehicular access

The positioning of a refuge chamber in a modern trackless(i.e. rubber-tyred equipment) mine should take into accountthe need for immediate vehicular access at all times andunder all circumstances. There have been international

reports of rescue teams arriving at a refuge chamber onlyto find the route blocked with vehicles abandoned by thevery occupants who are in need of rescue. While readyvehicular access is necessary, it is also critical to ensurethat the chamber is not exposed to damage from beingstruck by underground mobile plant.

14.2 Lighting

The darkness inevitable in the underground environmentcan be increased to a level of virtual impenetrability bysmoke from a fire. This can make the refuge chamber

KEY POINTS

ELECTRICAL

EQUIPMENT

All electrical installationsmust conform toAustralian StandardAS/NZS 3000:2000.

External terminationsmust have an ingressprotection rating of IP56.

All circuit breakers usedon the DC side must beselected on the basis ofDC current ratings.

Battery enclosures mustconform to AustralianStandard AS/NZS2676.1:1992.

Battery terminationsmust conform toAustralian StandardAS/NZS 3011.1:1992.

The provision of 240VAC general poweroutlets should bestrictly controlledin the undergroundenvironment.

The use of braidedor armoured cableis encouraged whenwiring undergroundinstallations.

A siren is essential to increasethe probability of finding therefuge chamber in extremeconditions. Collimatingthe sound helps intendingoccupants to locate the door


13/21


difficult to locate by people seeking safety. A high-intensitystrobe light fitted close to the door of the chamber canmake it easier to find in smoky conditions.

14.3 Siren

The probability of finding the chamber door can also besignificantly improved by a siren sounding close to the door.By placing the siren between two vertically mounted heavymetal plates, the sound can be collimated such that theloudest signal is heard directly in front of the door. The sirenwould only have to sound during the initial stages of anemergency, and the chamber occupants should be able to

turn it off when no longer required.

14.4 Layout

The site layout, including positioning of features such asrestricting bollards, lighting and signage, should ensureboth easy access and adequate protection of the chamber.Most important, however, is making sure the workforcebecomes thoroughly familiar with the discipline and rulesassociated with effective use of the refuge chambersprovided and, critically, the reasons why such rules exist.

15 Design and construction

15.1 Robustness

The construction of a refuge chamber should allow forthe circumstances in which it will be used. Moveablechambers are usually mounted on skids, allowing themto be towed or pushed to different locations in the mine.Underground roadways are typically rough, and theequipment fitted inside and attached to the chamberis commonly damaged by the vigorous movement, andtherefore the chamber and its equipment mountings mustbe very robust. Refuge chambers are usually positionedby being pushed into a cuddy formed in rock using eitherthe bucket of an integrated tool carrier (ITC) or a load hauldump unit (LHD). As a precaution, heavily constructedfenders should be fitted to the chamber to providesome protection from possible rough handling by thesemachines.

15.2 Seals

When in use, a refuge chamber must remain totallysealed off from the surrounding atmosphere. All accessdoors must fit properly and seals must always be in goodcondition. During transport between underground locations,the chamber structure may flex, causing doorframes todistort and welded seams to crack. The chamber structureshould be sufficiently stiff to resist this flexing and thedamage it can cause. After a chamber has been relocated,all seals should be fully tested before it is returned toservice.

The sealing of a chamber can also be compromised

if it is damaged by contact with mine vehicles.Such incidents normally occur when items of plantmanoeuvre nearby. The placing of substantial bollardsor pillars inhibiting close access to a chamber is aworthwhile precaution.

A closely fitting door, fully sealed when closed, is thenormal means of access to a refuge chamber. Althoughthe control system is designed to maintain a respirableatmosphere at a small overpressure relative to theexternal environment, it is possible for the outsidepressure to exceed that inside (e.g. during blasting).The vents on the chamber must be immediately selfsealing and the access door should be arranged to openoutwards. In this configuration, the seals will tighten ifthere is an external overpressure and prevent the ingressof external air.

15.3 Secondary means of egress

Some risk assessments have identified the risk that the mainaccess door could become blocked by a rockfall, vehicleor other obstacle. A secondary means of egress could beconsidered, with a strongly constructed hatch openinginwards and located as far as possible from the mainentrance.

15.4 Pressure equalisation

The system controlling the internal atmosphere should becapable of maintaining the chamber pressure just abovethat of the outside. To maintain this relationship, a pressureequalisation mechanism should be installed.

KEY POINTS

ACCESS AND SITE

LAYOUT

Consider the need forimmediate vehicularaccess at all times andunder all circumstances.

Use restricting bollards,lighting and signage toassist in ready vehicularaccess and preventdamage by undergroundmobile plant.

Ensure workforce isfamiliar with effective useof refuge chambers.

A high-intensity strobelight near the chamberdoor can expedite thelocation of the chamberin smoky conditions.

A siren with collimatedsound near the chamberdoor increases theprobability of finding thechamber door in lowvisibility conditions.

KEY POINTS

DESIGN AND

CONSTRUCTION

Moveable chambers,including equipmentmountings, must berobust.

All access doors mustfit properly and sealsmust always be in goodcondition.

A secondary meansof egress should beconsidered.

A pressure equalisationmechanism will maintainthe chamber pressurejust above that of itssurroundings.

If fitted, windows andretaining structures mustbe able to withstandexternal overpressure,particularly fromblasting.

Use a water-basedepoxy paint to preventcontamination of the

chamber atmosphere. Emphasise the hazard

posed by flammablematerials and ensuretheir exclusion fromrefuge chambers.


14/21


15.5 Window

The provision of a window adjacent to the door of arefuge chamber is a useful and simple feature. Itenables visual communication between the insideand outside, and can help lessen the feeling of beingenclosed, as discussed in Section 12. If fitted, awindow and its retaining structure must be capable ofwithstanding external overpressure, particularly thatcaused by blasting.

15.6 Painted surfaces

The interiors of refuge chambers are usually paintedwhite or another pale colour to maximise the effect ofinternal lighting and provide a reassuring environment.Paints containing hydrocarbon solvents can emitatmospheric contaminants for many years afterapplication. The effects of these emissions on thequality of the breathable atmosphere during a periodof extended chamber occupancy have not been fullydetermined. Consequently, it is a sensible precaution touse a water-based epoxy paint, which on curing does notemit contaminants.

15.7 Exclusion of flammable materials

Western Australian legislation generally prohibits theuse of flammable materials underground, except forspecific purposes and then only in limited quantities.There is no functional reason to have flammable materialsinside a refuge chamber but it is possible for a person

seeking refuge to bring such a substance with them, eveninadvertently. Training related to chamber use shouldemphasise the hazard posed by the presence of flammablesubstances and stress that they should not be brought intoa refuge chamber.

16 Maintenance

It is obvious that for a refuge to fulfil its purpose in a mine,it must be ready at all times for immediate, dependableuse. This requires an effective and rigorous inspection andmaintenance regime.

Based on an assessment of risk factors such as usage,location, and proximity to vehicular traffic and percussionfrom blasting, chambers should be inspected regularlyand basic tests carried out to ensure full functionality. Achecklist should be developed based on the manufacturersspecifications. All inspections should be recorded and acopy retained within the chamber. This has the advantage ofcreating an auditable record for scrutiny by management.Ideally, checks should be carried out daily by people witha vested interest in the correct functioning of the chamber people who may have to rely on it for their personal safetyor the safety of those they supervise. Any deficiencies shouldbe reported immediately to the Registered Manager andsenior engineer on site, who should arrange for the problemto be dealt with as soon as possible.

Where a deficiency cannot be remedied quickly, theavailability of alternative facilities must be considered.At the very least, underground crews must be informedof the non-availability of the chamber and advised of thealternative arrangements in the event of an emergency.

Responsibility for the ongoing integrity of a mines refugechamber or chambers should be clearly established bysite management. Clearly, any repair or maintenance workwill devolve to the engineering personnel, who should have

No flammable materialsshould be kept in or broughtinto a refuge chamber

KEY POINTS

MAINTENANCE

Refuge chambers mustbe ready to provide a safehaven at all times.

Institute an effective andrigorous inspection and

maintenance regime toensure full functionality.

Any deficiencies should bereported immediately tothe Registered Managerand senior engineer onsite.

Clearly establish whois responsible for theongoing integrity ofrefuge chambers.


15/21


access to the necessary information and equipment toundertake their duties.

The reliance on contractor-provided services, commonin Western Australian mines, can pose a difficulty forthe maintenance of refuge chambers. Some chambermanufacturers do provide maintenance services, butthese are typically only available at quarterly or evenlonger intervals. Day-to-day problems that affect thechambers integrity cannot be left until the next routineservice opportunity. On a mine where contract maintenancepersonnel are engaged in looking after specific typesof equipment, often specialising in one manufacturersproducts, the situation may arise where no specialist servicecapability is available for unusual items such as refugechambers. This is particularly so for electrical problems, asmany sites do not employ a permanent electrical technicianbut instead rely on visiting contracted personnel.

Irrespective of the arrangements for maintenance andrepair at any given mine, the principal employer has a dutyof care to ensure that refuge chambers are available atall times and fully functional for use as safe havens by theunderground workforce.

17 Testing

A commissioning test should be carried out when a refugechamber is installed for the first time underground. Thisshould include:

a full vacuum test to ensure the integrity of all seals

testing electrical power support in all operational states

mains in stand-by and recharge capability

independent supply in change over to stand-alonecondition and in change back to stand-by or recharge.

The condition of the refuge chamber should be fully andregularly audited. This should take place at six-monthintervals, but in any event within twelve months.

Operational experience indicates that the functionality ofa refuge chamber is most vulnerable during relocation. Afull commissioning check should be undertaken as soon aspossible after each move.

18 Further information

BRAKE, D.J., 2001, Criteria for the design of emergencyrefuge stations for an underground metal mine: Journal ofthe Mine Ventilation Society of South Africa, v. 43(2), 513.

BRAKE, D.J., and BATES, G.P., 1999, Criteria for the designof emergency refuge stations for an underground metalmine: Proceedings of the AusIMM, no. 304(2), 17.

BRNICH, M.J., VAUGHT, C., and CALHOUN, R.A., 1999, Icant get enough air proper self-contained self-rescuerusage: US Department of Health and Human Services,Public Health Service, Centers for Disease Control andPrevention, National Institute for Occupational Safety andHealth, DHSS (NIOSH), Publication no. 99160, 20 pp.

DEPARTMENT OF INDUSTRY AND RESOURCES, 2005, Tyresafety, fires and explosions guideline: Safety and HealthDivision, Department of Industry and Resources, WesternAustralia, 12 pp.

JONES, B., BRENKLEY, D., JOZEFOWICZ, R.R., WHITAKER,D., SHOTTON, J., and BOOTH, A.P., 2003, Use of self-rescuers in hot and humid mines: Health and SafetyExecutive, Research Report no. 180, 147 pp.

When considering thecapacity of the refugechamber, remember toinclude potential visitornumbers or a scheme torestrict group size, durationof visit, or both

KEY POINTS

TESTING

When a chamber isinstalled underground forthe first time

undertake a fullvacuum test to checksealing arrangements

test electricalpower support in alloperational states.

Full audits arerecommended at least

annually. The functionality of

chambers is mostvulnerable after relocation,and they should bechecked carefully aftereach move and preferablysix-monthly.


16/21


KOWALSKI-TRAKOFLER, K.M., VAUGHT, C., and SCHARF,

T., 2003, Judgment and decision making under stress: an

overview for emergency managers: International Journal of

Emergency Management, v. 1, p. 278289.

MASHA, 1998, Mine rescue refuge stations guidelines:

Mines and Aggregates Safety and Health Association,

Ontario, 120 pp.

Appendix 1 Legislative requirements

Mines Safety and Inspection Regulations 1995

Specific emergency precautions required to be taken for

underground mines

4.36. (1) This regulation applies to any of the followingpotential incidents

(a) a fire;(b) an accidental explosion (including a sulphide

dust or coal dust explosion);(c) a failure of the primary ventilation system;(d) flooding;

(e) an inrush of mud or tailings;(f) an inrush or outburst of gas; or(g) the extensive collapse of workings.

(2) The principal employer at, and the manager of, anunderground mine must ensure that, so far as ispracticable, the following things have been done toensure the safety of persons working undergroundin the mine in the event of a potential incident towhich this regulation applies

(a) an alarm system has been installed and aprocedure has been established for activatingthe system;

(b) a procedure has been established forthe prompt notification of rescue and firefighting teams;

(c) a procedure has been established forevacuating persons working underground;

(d) fire refuge chambers and fresh airbases are provided for persons working

underground;(e) provision has been made for the safety of drivers

of winding engines at underground shafts;(f) all employees are adequately trained and

retrained in emergency procedures andthe use of emergency equipment andfacilities; and

(g) emergency drills have been conducted on aregular basis.

Penalty: See regulation 17.1.

Note: The only authorised versions of the Act and regulations are thoseavailable from the State Law Publisher (www.slp.wa.gov.au), the officialpublisher of Western Australian legislation and statutory information.


17/21


Appendix 2 Hazards created byunderground ventilation practices

The hazard created by underground fires, particularly vehiclefires, in Western Australian mines is exacerbated by thewidespread implementation of so-called series ventilationsystems. In such systems, a portion of air that has beenexhausted in one workplace is successively re-used topartially ventilate others further along the circuit. Thisvirtually ensures that smoke and fumes generated by a fire inany given excavation will affect all others downstream of it.

Series ventilation systems are used in mining provinces

worldwide for development purposes and theirimplementation is commonly subject to specific regulation.Many mining operations in Western Australia rely solely onsuch systems, although they do not necessarily representgood practice.

Appendix 3 Unplanned usage ofrefuge chambers by visitor groups

The occasional presence of large parties of visitors (sixor more) in the workings of a mine is problematic whendetermining a realistic capacity for a refuge chamber. Thenumber of visitors could require the provision of very largecapacity chambers (25 or more occupants) or overpopulationof a smaller chamber. While overpopulation can probablybe sustained if the refuge chamber is operating on externalpower and services, the effective duration of the facility would

be severely reduced if the self-contained system was forcedto deal with the extra load.

The cost of providing significant additional refuge chambercapacity for possible occasional use is unlikely to be viable.A better solution is to assess the likely requirements ateach location and determine the number of visitors thatcan be accommodated with the anticipated workforce.Visitor group sizes could then be restricted accordingly andthe duration of visits kept to an acceptable minimum. Forlarger groups, consideration should be given to stoppingoperations that are likely to cause an emergency (suchas truck haulage in intake airways) until the visitors havecleared the area.

Appendix 4 Respirable air suppliedfrom compressors lubricated byhydrocarbons

With age, piston compressors become susceptible toa condition known as dieseling, whereby the volume oflubricating oil mixed with the air in the compressionchamber or chambers is sufficient to support spontaneousignition and sustain that process until the motive powerto the compressor is disconnected. This is a reasonablycommon condition and must be considered in any riskassessment relating to the supply of air to an underground

refuge chamber.

Similarly, the hydrocarbons contained in the compressionchambers of oil-injected screw compressors and slidingvane units are known to ignite under specific machineconditions.

Dieseling, in relation to piston compressors, and thesimilar condition that arises in oil-injected screw machinesand sliding vane units, can result in the airflow to anunderground refuge chamber being catastrophicallycontaminated with the irrespirable products of combustion,collectively called smoke. Inspection and maintenanceregimes must recognise these conditions and includemeasures to eliminate the risk of breathing air to a refugechamber becoming contaminated by combustion products.


18/21


Appendix 5 Potential independentemergency power sources

Independent supply

A second, totally independent power supply via cable can beinstalled in an escape system, shaft or dedicated borehole.

Battery powerpack

Power can be provided by a dedicated battery powerpack,usually rechargeable from the mine main electrical system.

From a safety, cost and utility perspective, this wouldtypically be a sealed lead acid system located in all casesoutsidethe chamber.

Electrical generators

Diesel engines, fuel cell units, compressed air motors,cryogenic power packs, conventional gas turbines, andclosed-cycle units such as Brayton cycle gas turbines havebeen proposed as prime power sources.

Diesel enginesand some fuel cell unitsrequire external(atmospheric) oxygen in order to operate. In the eventof a major underground fire, the oxygen supply can becompromised unless provision is made for an independentsource. The air consumption of a small two-cylinder dieselengine is such that it could evacuate a volume equivalent tothat of a standard sea container in less than two hours. Itmust be appreciated that this volume is whole air, not justoxygen.

An internal combustion engine, unlike the human body,cannot return the unused components of atmospheric airto its environment uncontaminated. Diesel engines do notoperate effectively, if at all, in oxygen-deficient atmospheresor in environments where there are significant quantitiesof gases such as methane or carbon monoxide. Researchin the oil and gas industries has shown that ingestingcombustible gases with intake air can mistime a dieselengine, and that mistiming can give rise to a flame path toatmosphere via the intake valves.

A number of refuge chambers already in use in WesternAustralian mines are equipped with emergency diesel

power, and more are being proposed. In the case of someunits, a solution to this hazard is to draw the intake air fromthe refuge chamber. A means of replenishing the wholeair supply to the chamber from an uncontaminated sourcemust be provided, but how this is achieved is unclear. Theuse of such systems is therefore not recommended.

Although exceptionally reliable in operation, compressedair motorsare clearly only as dependable as the supplyof compressed air. In the circumstances surroundingan underground fire, the compressed air supply is veryvulnerable to disruption and thus the use of this type ofsystem is not recommended.

Cryogenic(liquid nitrogen)power packshave enjoyedvarying fortunes as emergency energy sources. Whilethey have been shown to be quite effective, the storagesystems and associated support units require a high level ofmaintenance and are relatively expensive.

An electric generator driven by a gas turbine, in turnpowered by a closed-cycle systemsuch as the Braytoncycle, which draws energy from a high-temperature sourcesuch as molten salt, could conceivably be used to supporta refuge chamber in full stand-alone mode. However, inthe current context of Western Australian mines, such anarrangement would be:

very expensive

exotic it is likely that little, if any, knowledge of theoperation of such systems is available in the WesternAustralian mining industry.

While innovation is to be encouraged, it is recommendedthat the implementation of such systems be approachedwith great caution.


19/21


Appendix 6 Usage control andcommunication issues

The relatively sophisticated support systems proposedin this guideline require continuous supervision andmaintenance to ensure that they remain reliable.Unauthorised and non-emergency (including training)use can reduce the working life of the lighting andstand-by systems, and, in time, pose a hazard to trueemergency use. A modern refuge chamber, operating inthe stand-by condition, presents an attractiveenvironment underground. Western Australianexperience shows that chambers are used by theworkforce for purposes other than those relating to anemergency. Most disturbing are reports that chamberfacilities are being used to provide an oxygen fix, withinspectorate reports of chamber oxygen inventoriesbeing up to 50% deficient where no emergency use hasbeen reported or identified. This activity results inserious degradation of the chambers ability toprovide adequate support in an emergency, and is anissue for mine management to address under its dutyof care.

There are currently three start-up regimes under whichrefuge chambers can be operated:

manual

automatic

remote.

Manual start-up

Manual start-up by first occupant(s) requires that allpotential occupants are thoroughly trained in the process.This also presumes that the training is sufficiently robustto ensure that a person, possibly in a very agitated state,affected by smoke or fumes, or injured in some way, canreliably initiate and carry through the start-up processcorrectly. Clear instructions should be posted in obviousplaces to assist the start-up.

It should be noted that this form of start-up will notpreclude unauthorised or non-emergency use of thechamber.

Automatic start-up

Automatic start-up by devices sensing the presence ofpeople can readily be provided. The easy availability ofreliable passive infrared (PIR) devices, at reasonable cost,makes implementation of such systems comparativelysimple. Again, however, a difficulty arises withunauthorised or non-emergency use of the chamber.

Remote start-up

Given that most Western Australian undergroundmines are equipped with either leaky feeder or PEDcommunication systems, remote start-up from a

control centre following recognition of an emergencyunderground could be readily implemented. Thesesystems display increasing capability and reliability whileoffering significant benefits in terms of the control ofa number of underground functions. They have alreadybeen successfully used to activate remote features.

The main difficulty with these systems lies in how and whenthey would be activated. If control room personnel are to beresponsible for activating the underground response to anemergency then they need access to a wide-ranging, robustand rigorous monitoring and warning system. Two-waycommunication systems such as leaky feeders allow rapidand dependable transmission of information. The conditionsof a perceived underground emergency, as conveyed viawhatever communication system is available, will dependon the knowledge of the person doing the reporting, hisor her state of anxiety and physical condition, and otherfactors. There is a risk of false alarms being raised or majorproblems being understated.

A desktop computer, monitor, keyboard and monitoringdigital video camera are comparatively cheap andincreasingly common features in undergroundworkplaces. If a computer is connected to a controlcentre via a secure hard-wire link, visual observationand contact can be maintained, and the advantages ofautomatic start-up, control room alert and continuousnon-emergency monitoring can be exploited.

The availability of a secure, real-time visual up-link in arefuge chamber has significant benefits in the event of agenuine emergency. A chamber-based computer can beused to monitor the ongoing status of the various systems


20/21

32 Refuge chambers in underground metalliferous mines guideline

and visual, real-time chamber use. Although the energyrequirements of such a system would need to be assessed,its implementation would ensure that an undergroundrefuge chamber maintains its primary function and protectagainst unauthorised or non-emergency occupancy.Surface-based control room staff would become awareof emergency situations underground as quickly andcomprehensively as possible.


21/21

Mineral House100 Plain StreetEAST PERTH WA 6004

Telephone: +61 8 9222 3092Facsimile: +61 8 9325 2280Email: [email protected]: www.doir.wa.gov.au

Documents

WA Guideline Refuge Chamber