joint health and safety committee report on b.c. place stadium roof

8/8/2019 Joint Health and Safety Committee Report on B.C. Place Stadium roof

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InvestigationReport: BCPlaceRoofDeflationIncidentof

January5,2007

CompletedbytheInvestigationSubcommittee

SubmittedbytheBCPlaceJointHealthandSafetyCommittee

December21,2007


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ThisreportsprincipalauthorsaretheInvestigationSubcommitteeconsistingof:

JimHughes,CSP

JackieIng

JamesSwank

Thisreportwasreviewed,finalizedandsubmittedbytheBCPlaceJointHealth&Safety

Committee.


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InvestigationReport:BCPlaceRoofDeflationIncidentofJanuary5,20071

TableofContents

ExecutiveSummary............................................................................................................. 3

IntroductionandOverview................................................................................................. 6

SequenceofEvents............................................................................................................. 8

CommentaryonSequenceofEvents................................................................................ 16

EventAnalysisandDiscussion .......................................................................................... 17

Weather ........................................................................................................................ 17

RoofLoading ................................................................................................................. 19

RoofFabric .................................................................................................................... 28

PressureExcursion ........................................................................................................ 28

Equipment..................................................................................................................... 34

CrisisIdentificationandManagement.......................................................................... 36

Policies,ProceduresandTraining ................................................................................. 38

CultureIssues ................................................................................................................ 41

CausalAnalysisMethodologies ........................................................................................ 42

RootCause .................................................................................................................... 51

DirectCause#1 ............................................................................................................. 52

DirectCause#2 ............................................................................................................. 52

Conclusion ......................................................................................................................... 54

Recommendations ............................................................................................................ 54

Appendices........................................................................................................................ 57

AppendixA RoofSupportPressureControlSystemsDescription .......................... 58

AppendixBBCPlaceRoofLoadingCalculations .................................................... 61

AppendixCRoofSupportSnowMeltSystem ........................................................ 67

AppendixD InvertedPanelLoadingCalculations.................................................... 69

AppendixE WeatherData ....................................................................................... 72

AppendixFEmergencySnowMeltProcedures,Nov15,2006 .............................. 76

AppendixGGeigerEngineersReportData,Sept14,2007,#207813 ................... 79

AppendixHListingofPhotographsandVideoClips,inCDformat ........................ 80


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Executive Summary

Aftersustainingdamagetoawesttriangleroofpanel,thebuildingareaunderthedome

ofB.C.Placewassafelyevacuated,andthentheroofofBCPlacewassafelydeflatedina

controlledmanneratabout12:49pmonJanuary5,2007. Therewasnoinjuryasresult

ofthedeflation.

AttherequestofBCPlaceManagement,acomprehensiveinvestigationwasconducted

bymembersoftheJointHealth&SafetyCommitteeguidedbyanexperienced,external,

OHSConsultant. Theinvestigationsubcommitteehadthecompletecooperationof

buildingmanagement,union,staffandcontractors. Thisinvestigationteamalsoworked

closelywithKrisP.Hamilton,P.ENG,ofGeigerEngineering,thefirmthatdesignedthe

stadiumroof.

Theinvestigationisbasedonfactualdataandinformationandeventsleadinguptothe

deflation. Thepurposeofthisinvestigationwastofindfactsanduncoverrootcauses

thatweredirectlyresponsiblefortheevent,nottoassignblames,orfingerpoint.

Recommendationsinthisreportaimtopreventsimilarincidentsfromhappeninginthe

future.

Bypiecingalltheinformationtogether,thisreportpresentsapictureofwhattookplace

andthesequenceofeventsleadinguptothedeflation. Reconstructionofthedays

eventswerebasedonanumberofinformationsourcesincludingeyewitnessaccounts

boththroughinterviewsandwrittenreports,weatherreports,internalrecordsand

charts,newsmedia,inspectorsandprivateindividualsvideofootageandphotographs,

and

engineers

testing,

findings

and

preliminary

reports.

Thisreportgoesdeeperthansimplyrecordingthestepsoftheevent. WhiletheGeiger

Engineersreportcoverstheengineeringtechnicalaspectsoftheincident,the

InvestigationSubcommitteeexaminedabroadrangeofcausalfactorsthatwere

identifiedduringtheanalysisphaseofinvestigation. Inadditiontodealingwithmany

complextechnicalaspectsoftheevent,thesubcommitteealsolookedcloselyintothe

operationalside. BoththeEngineersreportandthisinvestigationreporttaken

together,addressthecompletescopeoftheroofdeflationincident.

EventDescription

Simplystated,heatandthenumberoffanscirculatingairattheroofwerenot

increased,whensnowwasimminent,norweretheyincreasedwhensnowwas

observed. Asthesnowaccumulated,unchecked,theroofbecameheavilyloadedtothe

pointitstartedtoloseitsshape.Thechangeintheroofwasnotnoticeduntilthemain

speakerclusterwasobservedtobeverylow,andthecenteroftheroofappearedvery

flatontheinside.


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Atthispointbuildingpersonnelreactedbyincreasingbuildingpressureandactivating

thesnowmeltroofheatingsystem. Theroofshapedidnotappeartoberecoveringas

expectedbecausetherequestedcomputersystemspressuresettingwasconflictingwith

thebuildingspneumaticcontrolsystems.Thiscausedthereliefventstobleedoffthe

intendedpressureincrease. Atthispointthepressuresetpointonthepneumatic

controlsystemwasincreased. Whenthesystemsfinallyreactedtothecommands,the

combinationofsetpointincreaseandotherfactorscausedabriefpressureexcursion,

substantiallyabovetherequestedpressuresetpoint,whichquicklybutbrieflyrestored

therooftoahigherthannormalprofile. Thebuildingspneumaticreliefsystemwasvery

slowtoreact,butafterafewminutesitbroughtthepressurebackdowntotheset

pointpressure. Bynowitwastoolateastheunstablemassorpond,consistingof

water,snowandicetomovetowardsthewesttrianglepanel. Itwasthemovementof

water,snowandicefrompaneltopanelthatcausedtheinvertedpanelstopopup,

creatingveryloudsoundsrecountedbywitnesses. Asthemassreachedtheendofits

travelatthewesttrianglepanel,theresultingavalanchecausedthewesttrianglepanel

tobulgeinwardabout7.5to8feet. Atthesametime,thismasshittheringbeamarea

belowthewestpanelwithatremendousforcewellbeyondtheroofpanelmaterials

designloading. Atearonthewesttrianglepaneloccurred.

Asthedamagedpanelcontinuedtotear,itwasnolongerpracticaltomaintain

adequateinternalpressureasfurtherdamagewasimminent. Thedecisionwasmadeto

safelyevacuatethebuilding,andtostartturningoffpressuresupportsystemswhich

easedtheroofdownintoitsconstructionpositioninasafemanner. Theroofslowly

defaultedtoitsconstructionpositionapproximately6metersabovetheStadiumfloor

andseats.

Oncetheroofwasstableinitsconstructionposition,asafetyandstructuralassessment

wasconducted. Aseachareawasdeemedsafe,workersweredirectedtobegin

assessmentandwatercontrol. Anumberofprofessionalswereonsitetoassessthe

damagebothupontheringbeamandinsidetheStadium.

CausalAnalysisandDiscussion

Basedonthefactualinformationanddata,keyfactorsarehighlightedandexaminedto

determinehowtheyhadcontributedtotheincident. Thesefactorsareweather,roof

loading,rooffabric,equipment,policiesandprocedures,Stadiumculture,andcrisis

management. Differentcausalanalysismethodologieswereusedinfleshingoutthe

detailsandultimatelypinpointingtherootcause.

Itisimportanttonotethatevidencecollectedduringthisinvestigationclearlydispels

anynotionthatpersonnelotherthanthecontrolroomoperatorwereflippingdifferent

switchesatthesametimeinattemptingtorecovertheroofincrisis. Allcommands

wereinitiatedbythecontrolroomoperatorthroughthebuildingautomationcomputer

andnotbypersonnelturningonfanswithswitchesfromtherearHoneywellpanel.All

therequestedpressuresettingswerewellwithintheknownsafeoperatingrangeofthe

building.


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RootCause

Thecausalanalysisofthiseventpointsdirectlytothelackofeffectivepolicies,

proceduresandtrainingastherootcauseofthisincident.

Furthermore,ageneralblindnessandlackofunderstandingandtrainingrelatedto

theroofsupportsystems,operatingwithinanenvironmentwherepoliciesand

procedureswerefullofholes,hadallowedsnowaccumulationtogounnoticed. Pooror

verylittleroofincrisisidentification,assessmentandtrainingalongwithconflicting

controlroomsystemsallcameintoplaytocausethedamagetothewesttrianglepanel.

Recommendations

Thecorrectiveactionsclearlysupportedbythisinvestigationcanbebrokenintothe

following5categories:

1.Create,inform,implementandpostaNoSnowAccumulationpolicyforthe

roof. ThispolicywouldbecomethegoalfortheStadiuminkeepingtheroofup.

Itdefinesthefacilityphilosophyandmakesitcleartoallpartiesthateveryeffort

willbemadetopreventsnowfromaccumulatingontheroof.

2.Withoutfurtherdelay,completeanexternalauditofStadiumOperationsto

focusonpolicies,proceduresandtrainingthenimmediatelyimplementthe

correctiveactions. ThisincludesriskidentificationandmanagementinStadium

maintenanceandoperations.

3.Immediatelyhaveaqualifiedperson,assistedbyaqualifiedtestinglaboratory

conductaphysicalassessmentoftheroofmaterialandseamsadjacenttothe

ringbeamstartingwitheachofthetrianglepanels.Makethenecessary

corrections.

4.Haveaqualifiedperson,knowledgeableintheseroofsystems,assess,modify

andupdateroofsupportcontrolsystemsincludingamethodforthecontrol

roomtoseetheroofandknowwhenitisincrisis.

5.Completeacomprehensiveindependentexternal,auditoftheOccupational

Health&Safetyprogramofthisfacilityandimplementrecommendations.


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IntroductionandOverview

ThereportsummarizestheJointHealth&SafetyCommitteesincidentinvestigationof

theBCPlaceroofdeflationincidenttookplaceonJanuary5,2007.

FollowingthecontrolleddeflationonJan5,2007,attherequestofBCPlace

Management,aninternalinvestigationwasconductedbymembersoftheJointHealth

&SafetyCommitteewiththeassistanceofanexternalOHSConsultant. The

investigationisbasedonfactualdataandinformationandeventsleadinguptothe

deflation. Membersontheinvestigationsubcommitteeandthejointhealth&safety

committeelefttheirmanagementorunionhatsoutsidetheinvestigationdoortoensure

theinvestigationwasdonethroughanobjective,impartiallens. Thepurposeofthis

investigationwastofindfactsanduncoverrootcausesthatweredirectlyresponsible

fortheevent,nottoassignblames,orfingerpoint. Therecommendationsputforthat

the

end

of

the

document

aim

to

prevent

similar

events

from

happening

in

the

future.

Bypiecingalltheinformationtogether,thisreportpresentsaclearpictureofwhattook

placeandthesequenceofeventsleadinguptothedeflation. Reconstructionofthe

dayseventswerebasedonanumberofinformationsourcesincludingeyewitness

accountsboththroughinterviewsandwrittenreports,weatherreports,internalrecords

andcharts,controlroomlogs,newsmedia,inspectorsandprivateindividualsvideo

footageandphotographs,andengineerstesting,findingsandpreliminaryreports.

Thisreportgoesdeeperthansimplyrecordingthestepsoftheevent. WhiletheGeiger

Engineersreportcoverstheengineeringtechnicalaspectsoftheincident,the

InvestigationSubcommitteeexaminedabroadrangeofcausalfactorsthatwere

identifiedduringtheanalysisphaseofinvestigation. Inadditiontodealingwithmuch

Stadiumspecifictechnicalinformation,thesubcommitteealsolookedcloselyintothe

operationalside. BoththeEngineersreportandthisinvestigationreporttaken

togetheraddressthecompletescopeoftheroofdeflationincident.

Thisinvestigationreportconsistsofvarioussections,startingoffwithadetailedaccount

ofthedaysevent,followedbycommentariesandindepthdiscussionsonkeyelements

andfactorstodeterminetheirsignificanceintheroofdeflationincident. Casualanalysis

employingdifferentmethodologieswasusedtoidentifyrootcausesandassociated

contributingcauses.

AsthisreportcontainsmanytechnicaltermsspecifictotheBCPlacesroofsupport

system,whichmightbeunfamiliartosomereaders,pleaserefertoAppendixA Roof

SupportPressureControlSystemsDescription. Forthepurposeofkeepingthemain

reportsuccinct,technicaldataandsupportinginformationaremadeavailableinthe

appendices.


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Thisinternalinvestigationhadthecompletecooperationofbuildingmanagement,

union,staff,contractors,professionalsandprivatecitizens. Thisinvestigationteamalso

workedcloselywithKrisP.Hamilton,P.ENG,ofGeigerEngineering,thefirmthat

designedthestadiumroof. Wewishtoexpressourappreciationtoallthesepartiesin

theirassistanceintheinvestigatingprocess.


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SequenceofEvents

TheControlroomoperatesina12hrrotation,0700to1900asdayshift,1900tonext

day0700asnightshift. ThissequenceofeventsinitiatesfromthenightshiftofJan4

(1900ofJan4/07to0700ofJan5/07). Atypicalcontrolroomshiftisatwostaff

memberteam:aControlRoomOperatorwhoisresponsibleforthemonitoringof

systemsandcontrolsofthebuildingandanEastAirlockSecuritywhoisresponsiblefor

internalandexternalsecurityandpatrolofthebuilding.

Thedatacollectedduringtheinvestigationsupportsthefollowingscenario:

Jan4

Theshiftwasdescribedtohavestartedlikeanyother,normal,uneventfulnightshift.

23:13 alowtemperatureoutsidealarmcameinindicatingandprintingoutnearfreezing

outsidetemp,watchforsnow.

Jan5

04:10, Smokealarmonfirepanel,Zone3,sentEastAirlock(EAL)Securitytocheckitout.

Showerincoachslockerroomwasleftonandsteamsetoffalarm. Turnedoffshower.

04:20, ControlRoom(CR)Operatortriedtoresetalarm,butthewholepanellituplikea

Christmastree. Allindicatorlightscameon.

04:25, CROperatorcalledsupervisorbutcouldnotgethimathome,socalledthe2nd

supervisorathome,andleftmessageonmachineastherewasnoanswer.

04:27, Becausetheyhadnoideawhythefirepanelwasalllitupthesecuritypersondecidedto

goonactivefirewatch.

04:29, 1stsnowconditionalarmcamein. 1hourdelaystartedtocountdown(systemdefault

setting).TheCROperatoractivatedthe15hourdelayontherearHoneywellpanel.(See

AppendixCRoofSupportSnowMeltSystem)

04:30, TheroofsensorsentamoisturealarmandprintedPrecipitationdetectedatroof

sensors. (thesystemisconfirmingthatbothlowtemperatureandmoistureexist,

showingarealpossibilityofsnow).

04:31, CROperatorwentoutsideofeastairlocktoobserveweather.Itwassnowinglightlybut

hecouldnotseeanyaccumulationontheroof.

04:40, CROperatorcalledEnvironmentCanadaweatherofficeforreport. Theweatherreport

wasgivenasfollows:GREATERVANCOUVER.TODAY.PERIODSOFSNOWCHANGINGTOPERIODSOFRAINTHISMORNING.

RAINFALLAMOUNT20TO30MM.BECOMINGWINDY.HIGH8.TONIGHT.PERIODSOFRAINENDING

OVERNIGHTTHENCLOUDYWITH30PERCENTCHANCEOFSHOWERS.AMOUNT10MM.WINDY.LOWPLUS

5.

05:00, Bythistime,neitherofthesupervisorshadcalledback,sotheCROperatordecidedto

calltheDirectorofOperationsregardingthefirealarm,andsnowconditionalarm.The

DirectoraskedtheOperatortoresetthefirepanelandwastoldCRhadtriedthat,but

thewholefirepanellituplikeaChristmastree. Directorsaidhewouldbetherearound

6:15to06:30.

05:05, Engineeringsupervisor(2nd

call)calledbackinresponsetothemessagetheyleft.CR

Operatortoldhimhehadalreadyspokentothedirectorandhewasonhiswayin.


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Supervisordiscussedfirepanelproblemandhadtoldthemnottoworryaboutitand

thetechnicianwouldfixitwhenhegetsinat08:00.

05:42, UnbeknownsttotheCROperator,theEnvironmentCanadaweatherofficehadnow

issuedanewreportat0542:GREATERVANCOUVER. TODAY. PERIODSOFSNOWCHANGINGTOPERIODSOFRAINTHISMORNING.

SNOWFALLAMOUNT2CM. RAINFALLAMOUNTS20TO30MM. BECOMINGWINDY. HIGH8. TONIGHT.

PERIODSOFRAINENDINGOVERNIGHTTHENCLOUDYWITH30PERCENTCHANCEOFSHOWERS.AMOUNT

10MM.WINDY.LOWPLUS5.

05:53 1stsnowconditionalarmcancelleditself,indicatingsnowconditionshavecleared.

05:59, 2nd

snowconditionalarmcameinfromthesensors,1hourdelaystartedtocountdown

bydefaultofthesystemandthe15hourdelaybuttonwasmanuallyactivated.

06:09, 2ndsnowconditionalarmcancelleditself,indicatingsnowconditionshavecleared.

06:14, 3rdsnowconditionalarmcamein,1hourdelaystartedtocountdownbydefaultofthe

systemandthe15hourdelaybuttonwasmanuallyactivated.

06:20, TheDirectorarrived,reviewedsituationwiththeCROperator,thenwentintothe

Operationsofficeandprintedoutthelatestweatherreport.

06:27, 3rdsnowconditionalarmcancelleditself,indicatingsnowconditionshavecleared.

Itshouldbenotedatthispointthatallstaffandsupervisorsthatwereinterviewedhadspecificallynotedsnowaccumulationofupto2inchesofslushywetsnowonthegroundoutside

ofthestadiumastheywerestartingtoarriveatwork. Somereportedrain,somesleetandsome

snowbutallnotedtheaccumulationontheground.

06:45, ThedirectorspoketothenextshiftCROperator(07:0019:00)ashehadshowedup

earlyforhisshift. GavehimacopyoftheEnvironmentCanadaweatherreportissuedat

05:42whichhehadprintedoutwhenhegotin.HealsoreiteratedwiththeCROperator

towatchtheweatherandapplyheatathisdiscretion.

06:45, Atthistime,theEnvironmentCanadaweatherofficeissuedanupdatedadvisory

indicatingthefollowingbutitwasunknowntostaff.GREATERVANCOUVER,SNOWFALLWARNINGINEFFECT.

TODAYPERIODSOFSNOWCHANGINGTOPERIODSOFRAINTHISMORNING. SNOWFALLAMOUNT2CM

EXCEPT10CMOVERHIGHERTERRAIN.RAINFALLAMOUNT20TO30MM.WINDY.HIGH8,

TONIGHT.PERIODSOFRAINENDINGOVERNIGHTTHENCLOUDYWITH30PERCENTCHANCEOFSHOWERS

AMOUNT10MM.WINDY.LOW,PLUS5.

06:57, Controlroomshiftchange,newoperatorsignedon.

Itshouldbenotedatthispointthatmostoftheinterviewedstaff,commentedthatthe

temperatureinsidethebuildingthatmorningwascoolerthanusual.Duringthemorningof

January5,2007,theinsidebuildingtemperaturewassetat10degreecelcius. Thisisthe

minimumtemperaturesettingallowed. Therewere2adjustablespeedfans(ASDs),#10inFan

Room#5inFanRoom#8.Thecomputersetpointwassetat250Pa. Becauseitwasa

turfupday,toincreaseventilationforthedieselpoweredforklift,twoconstantspeedfans

(CSFs)#4inFanRoom2,fan#14inFanRoom7wereturnedon.These2constantspeedfans

areinrecirculationmodebecausethebuildingpressureismaintainedbythecomputerdriven

AdjustableSpeedDrives. Thecomputerpressuresetpointwasat250Pa,thepressureandrelief

controllers,onthemanualHoneywellcontrolpanelweresetat250Paforthepressure

controllersandat300Paforthereliefcontroller. Thisappearstofollowthebuildingsprocedure

manual. Soupuntil12.33,therewere2ASDsand2CSFsinoperation.

08:10, Shortlyaftershiftbriefing,oneworkerfromtheTurfupcrewcommentedtotheCR

Operatorandasupervisor:WhyamInotwearingmytshirtinsidethismorning?The


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responsewaseconomicsdictatewedonotneedtheheat. (Theworkerherereferredto

whensnowmeltison,theStadiumwouldbeheatedandwarmenoughtowearonlyat

shirt).

08:16, CROperatorturnedonconstantspeedfan4inroom2.Thisisastandardprocedurefor

turfupoperation.

08:17, 4thsnowconditionalarmcamein.1hourdelaystartedtocountdown.

08:18, CROperatorturnedonconstantspeedfan14inroom7.Thisisalsopartofthestandardprocedureforturfupoperation.

08:34, the15hourdelayforsnowmeltwasmanuallyactivated.

09:00, AworkerhadbeenworkingonLevel2andnoticedoutsidesnowaccumulation. Worker

thenwentintoControlRoomandaskedwhysnowmeltwasnton.

10:05, 4thsnowconditionalarmcleareditself,indicatingsnowconditionshavecleared.

10:15, Aturfupworkernoticedthespeakerclusterwashangingataveryoddandcrooked

angle.

10:30, DutyManager(DM)whendoingroundsonlevel2,notedabout2inchesofwetsnowon

theplazadeckwithwhatappearedtobeverywetlookingfootprintsinit. Whenrounds

werefinishedtheDMwentintothecontrolroomandreportedherobservationtothe

CROperator.TheCROperatorlookedinthecameraattheroofandsawnosnow,so

toldtheDMthatthesnowhadslidoffoftheroofandnottoworry.Whatwasnot

realizedwasthattheroofareavisibletothecamerawasabovethesectionofthe

stadiumaffectedbyFanRoom#2. Assuchtheresidualheatcombinedwiththeair

circulationfromthefaninFanRoom#2hadmeltedthesnowinthatarea. Thecamera

didnotseetherestoftheroofwhichwasstillcoveredwithsnowandpossiblyfrozen

snow.

10:55, Thepressuredialchartchanged. ThisisadailyactivityintheControlRoom,pressure

dialchartsarechangedevery24hoursat1100. OnJanuary5,timeindicatedonthe

chartseemstobeslightlyoutofsyncwhencomparedtothecomputerdataprintout

logs. Thechartappearstobeabout3or4minutesbehindtheactualtimeline.

11:00, UnbeknownsttotheControlRoom,EnvironmentCanadaweatherofficeissuedagaina

snowfalladvisory: GREATERVANCOUVERSNOWFALLWARNINGINEFFECT

TODAY.PERIODSOFRAINATTIMESMIXEDWITHSNOWNEARNOON. SNOWFALLAMOUNT2CMEXCEPT

10CMOVERHIGHERTERRAIN.RAINFALLAMOUNT20TO30MMWINDSOUTH40TO60KM/HBECOMING

SOUTHWEST30GUSTINGTO60EARLYTHISAFTERNOON,HIGH6

11:01, 5thsnowconditionalarmcamein. 1hourdelaystartedtocountdown,andthe15hour

delaybuttonwasmanuallyactivated.

11:20, EastAirlockSecurityandtheDirectorofOperationswentoutsidetotheTerryFoxplaza

todealwithavagrant. EALSecurityreportedtherewaswetsnowfallingandnoticeda

littlesnowstickingtorooflookingupfromTerryFoxarea.

11:30, TwoworkersfromtheturfupcrewwentoutsideattheDisabledEntrancebytheturf

storageareaandnoticedheavy,bigflakesofwetsnowwasfalling.

Lunchbreak,from12noonto12:30sonoonewasworkingonthefieldduringthistime.

12:06, 5thsnowconditionalarmcleareditself,indicatingsnowconditionshavecleared.

12:10, CROperatorlefttheControlRoomtograbapop,hewalkedouttotheeastfield

entranceandlookedupattheroof. Herememberstherooflookednormaltohim.

12:20, Contractworkercamebackearlyfromlunchandnoticedthelowspeakercluster,(about

15or20feetoffoffieldlevel). Hewatchedforafewminutesnoticedtheroofwasvery


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flat(flatterthanhehadeverseenit)thenwastoldtostaybackfromthefieldandto

remainintheconcourse.

12:31, Astaffmembernoticedwhenreturningfromlunch,walkingonthefieldthroughthe

EastAirlock,themainspeakerclusterwasverylow,about10feetabovethefield. He

thenlookedupattheroofandnoticedsomethingveryodd.Herealizedtheentiretop

areaoftheroofwasflat.Hedefineditwasflatfromtheinsideanchorpointofthe

suspensioncablesofthesatellitespeakerswhicharelocatedaroundtheperimeteroftheroof.HethenwenttotheDutyManagerandreportedthis.Itwasalsoobservedthat

3or4ofthediamondsectionsaroundtheareaofthespeakerclusterwereinverted.

12:32, DutyManagernoticedworkersstaringattherooffromtheEastAirLock,whenshe

returnedfromlunch. Sheobservedthespeakerclusterwasactuallysittingonthefield

atthispointandshethoughtitwasoddbecauseitwouldblocktheforkliftaccessfor

theturfupoperation. Thenshenoticedtheroofwasflatlikeapancake.Shetold

workerstostayclearofthefieldandthenwenttotheControlRoomtoreportthe

situation.

Atthispointseveralstaffhadnowcomebackfromlunchandnoticedthegrowingcrowdof

peoplewatchingtheroofasitseemedveryeerie. Aroundthebuildingatvariouslocations

staffshadnoticedtheroofflatandlowandwerenowstartingtowatchwhatwashappening.

Thoseinterviewedwitnesseswhowereonsitethatday,allreportedseeingtheroofbeingflat

andunusuallylow,aswellas:flatlikeapancake,wrinkledlikeaprune,couldnotseethe

sideoftheringbeam,onesidepusheduplookinglikeintestines,speakerclustertiltedata

45degreeangleandwaterwasdrippingthroughthevents,theroofwasdimpling,etc..

12:33, Twoworkersreturnedfromlunch,andreportedthesituationtosupervisors

immediately. BothengineeringsupervisorsandastaffmemberranintotheControl

Room. TheyimmediatelyalertedtheCROperatorthattheroofwascomingdown.

12:33, Itisnowapparentthattheroofisincrisis. OnesupervisorinstructedtheCROperatorto

increasethepressureto300Paandpreparethebuildingforsnowmelt. Theother

supervisorwenttothebackwiththeotherworkertochecktheMagnehelicPressure

Gauge.

SeveraladditionalstaffandsupervisorsarenowintheControlRoom. Ithasbeendetermined

thatatleast5people(supervisors,workerandCROperator)wereintheControlRoom. TheCR

Operatornotonlyhavingtodealwiththeroofincrisis,buthenowhasagroupofpeople

offeringwellintentionedassistanceandprovidinginstructions.

ITMUSTBENOTED,theonlypersonissuingcomputercommands,andadjustingtheHoneywellpressureandreliefcontrollers,intheControlRoomuptothepointofthepanelfailure,wasthe

CROperator.

Thecomputerpressuresetpointwasincreasedfrom250Pato300Pa. Thissetsthe

pressureparameterfortheadjustablespeed(ASD)fans. Atthistime,therewereonly2

ASDfansrunning. TheASDfanswerenowworkingtoincreasepressuretowards300Pa.

The2constantspeedfanswhosedampersarecontrolledbytheHoneywell

pressure/reliefcontrollerswereinrecirculationmode,astheyhaveachievedthe

controllersetpointof250Pa.ThepressurecontrollerontheHoneywellpaneliskeeping

theoutsideairdampersclosed,asithasthe250Paitissetfor.Itisimportantto


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understandthattheconstantspeedfandampers(CSFs)taketheirpressuresettings

fromtheHoneywellpressurecontrolleronly,andcomputersetpointchangesdonot

affectCSFs.

**note,Basedonwitnessaccountsandanalysis,thepressureandreliefcontrollersonthe

HoneywellPanelatthebackofthecontrolroomdidnotappeartohavebeenchangedtoreflect

theincreaseincomputersetpointfrom250to300Pa.Theprocedurewhenchangingthe

computerASDsetpointto300PaistoimmediatelygotherearHoneywellpaneland

changethepressurecontrollersetpointto300Paandtochangethereliefcontrollerset

pointto350Pa. WhenASDfansarerunningthereliefcontrollersetpointmustalways

be50Pahigherthanthecomputer/pressure controllersetpoint.

12:34, Fan#7(ASD)inroom4wasturnedonbycomputercommandbytheCROperator. This

fanwastakingitssettingfromthecomputersetpointof300Pa. Forabriefperiodof

30secondsto1minute,therewillbeairlosscausingasmalldropinpressure,(atypical

occurrenceafterafanisturnedon),butshortlyafterthat,all3ASDfansshouldbe

rampingupto300Pa.

EvidenceindicatesthatbecausetheASDfanstaketheirpressuresettingfromthecomputerset

point,whichisbasedonanaveragefromareadingtakenineachofthe8fanrooms,they

usuallyshootalittlehigher(8to10Pa)thantheMagnehelicpressuregaugethatcontrolsthe

relief.Asettingof300Paonthecomputerisreallyabout310Pa.ontheMagnehelic.Thisisnot

achievablebecausetheHoneywellpressurecontrollerwasnotresetto300andtherelief

controllerto350. Theywerestillontheoldsettingsof250and300. ThismeanttheASDfans

werenotgoingtobeabletohitthedesiredpressureof300Pabecausethereliefdamperswill

openanddrainoffthepressurebeforetheASDscouldreachthesetpointof300Pa.Therelief

systembeingpneumaticallycontrolledissoslowtoreact,needsabout2minutestoopenand1.5

minutestoclose,thatthemaximumpressuretheASDfanscouldhopetoachieveisabout270to

280Pa.

12:36, CROperatorcalledthesteamplanttoaskforsteamtogotosnowmeltmode.Hegot

theOKasthesteamplanthadbeenpreparedforhiscall. Hethenoverrode

temperatureandmoisturesettingsontheEnergratedcomputerinpreparationfor

immediatesnowmelt.

12:36, 15hrdelaytimerforsnowmeltwasactivatedonthebackHoneywellpanel.Atthispointtherewasgrowingconcern,becausewith3ASDfansrunningat100%toincrease

thepressurebuttherewasverylittlemovementintheroof,andthepressurehasbarelymoved

up. Noonerealizedreliefsettingsonthepressureandreliefcontrollerswereconflictingwiththe

computersetpointfortheASDfans. Thereliefcontrollerwasopeningthereliefdampersto

reducepressurebeforethecomputersetpointcouldbeachieved.

12:37, Aworkerhadgoneouttothefieldandobserved3invertedpanelsabovethespeaker

clusterandreportedthisinformationtoControlRoom. Engineeringsupervisoratthis

pointdecidedtoruntotheTechShopandgetatechniciansassistance. Heknewthe

technicianwashavinghislunchthere. Heranintotheshopandtoldthetechnicianthat

theRoofwasfallingandhemustgointothecomputerandraisethepressureto400

Pa.


15/82


Thetechnicianfollowedhissupervisorsinstructionsandproceededtologontothe

computersystemfromhisshopandmakethechanges. Ittookabout4minutestoenter

thedata.

Itshouldbenotedthecomputersetpointchangedbythetechnicianwouldnothave

beeneffectiveforthesamereasonabove. BecauseHoneywellreliefcontrollerwasstill

at300Pa,thereliefsystemwouldreacttoreducepressure;andthereforeprevented

theASDfansfromachievethis400Pasetpoint.

12:37to12:38, meanwhileintheControlRoom,CSFs#12,then#5wereturnedonatthe

computer.

12:39, ASD#2wasturnedonatthecomputer.Forabriefperiodof30secondsto1minute,

therewillbeairlosscausingasmalldropinpressureasthisASDfancomesonline.

12:40, theCROperatoratthispointactivatedsnowmelttoapplyheatdirectlytotheroof.

Activationofsnowmeltatthispointimmediatelyoverrodethecommandsfromthe

technician,asittakespriorityoverandsetsthecomputersetpointimmediatelyto300

Pa. Theremotesetpointrequesttoputpressureupto400wouldhaveatbestbeenin

effectverybriefly. Atthispointthecomputersystemwasunderseverestressandsome

datawasnotevenacknowledged.Muchofthedatabeingprintedfromthecomputerin

thecontrolroomwasoutofsequence.

Justpriortotheprevious3fansrampinguptospeed,theHoneywellpressurecontroller

andthereliefcontrollerwereresetto350Parespectively.Thishappenedjustasthe

pressurelosswasineffectfromASD#2startingup.

Nowallthingsarechanging.AssoonasthesettingswereontheHoneywellpanel. Therelief

systemswouldbegintoclosedowntopreventairloss,the4ASDfanswouldhavequickly

achievedtheprevioussetpointof300Pa. LikelybythetimetheASDfansachievedthesetpoint

of300Pa.,thereliefdamperswerecompletelyclosedandthe4constantspeedfanswerenow

gettingfulloutsideairastheywerepumpingpressuretoasetpointof350. Withallfourcsf

fansworkingtowards350Pa,itwaslikelythissetpointwasachievedveryquickly.

Thisistheturningpointfromanoverloadedrooftoanavalanche.Thestagewasset.WithbothHoneywellpressureandreliefcontrollerssetat350Pa,thishadsetuptheperfectsituation

forthepneumaticreliefcontrolsystemtocauseapressureovershootabovethesetpoint.

12:41to12:42

Pressurerapidlyincreasedto520Paorapprox68%onpressurechart.Ananalysisofthe

Honeywelldialchartshowsittookabout2minutesforthepressuretokickupto520

Pa. Bythetimethereliefcontrollercouldreactandopendamperstoreducepressure,

thebuildingpressurehasnowreached520Pa.

Thereliefcontrollerisonapneumaticsystem;thereforeitwouldhavetaken2minutesforallofthedamperstoopen. Thisdelayedthesystemsabilitytodrainoffexcess

pressure. Oncethepressurehadpeakedat520Pa,thereliefcontrollerwouldnowhave

allreliefdampersfullyopentoreducepressure,andthepressurecontrollerwouldnow

fullyblockedoutsideairandonrecirculationfortheconstantspeedfans. TheASDfans

wouldbeatidlespeed. Thepressurethenbegantodroprapidlybackdowntotheset

point. Thepressureundershotbelowthesetpointreachingalowpointof33%or247

Pa. Asthepressuredroppedbelowthesetpoint,computercontrolledASDfansreacted

quicklyandbegantoraisepressure.


16/82


SeeanalysisonPressureExcursion

12:43, AnavalanchewasheardbywitnessesontheTerryFoxplazasideoftheroof. (Section7

10)Witnessesreportedalow,rumblinghummingsound.

12:44to12:46 Staffnowstartedhearingthesoundofsnowmovingontheroof. Theyreporteditasa

lowroar,Thump,thump,thump,roofwasshakinglikeablanket,agiantwas

runningontheroof,jetplanestakingoffandothersequatedittothesoundofan

elephantrunningthroughthelivingroomtowardsthewestendandanotherdescribed

therewasawhooshingsound. Oneverydetailedaccountsaidthatheobservedalarge

bulbouspillowormass,likeafistbeingpusheddownontherooffromabove,moving

throughthediamondpanelsonebyonethenitmovedontothetopofthewesttriangle

andinvertedit,thenitmoveddowntowardstheringbeamatatremendousspeed.This

bulgewaslargeenoughthatitcompletelyblockedtheviewoftheclockwhenitgotto

thebottomofthetrianglepanel,(atleast7or8feetdeep).Hesaidwhateverthebulge

washadalotofweightinit. Inrapidsuccessiontherewasaloudcracklikesound,sort

oflikethesnappingofabullwhip,thentheSeikoclockexplodedandatearappearedin

thebottomcenterofthewestpaneljustabovetheringbeam.Thetearseemedtostop,

momentarily,atabout12feetinlengththenwaterandicecamepouringin.Thetear

thentookoffacrossthebottomthenuptheleftside. Asthewaterandicecontinuedto

pourin,peoplecontinuedtoobservethetearopenedtotheleftthenrightandthen

peeledopenlikeacanofsardines,youcouldhearaveryloudcrackingorflapping

soundasthepanelwaswhippedbytheairrushingoutofthebuilding.

12:46, Thepressurewasonitswaybackuptothesetpointof300Pawhenthewesttriangle

panelfailed. Atthispointthepressurewasabout37%or277Pa.Itappearsthataspan

ofabout12minuteselapsedfromtheinitiatingcorrectiveactiontothepanelfailure.

12:48, Atthispoint,thesystemisunabletomaintainadequateinternalpressuretosupport

theroof,andfurtherdamagewasimminent. Thedecisionforacontrolleddeflationwas

made.TheevacuationannouncementwasmadebytheDutyManagerandthenthe

controlroomoperatorplayedtheevacuationrecordingoverthePAsystem.

12:49, Fans#4,5,12&14weresequentiallyturnedofftoallowacontrolledandgentle

deflationoftheroof.

12:50, Whenthepressurewentbelow180Pa,thecomputerautomaticallyturnedonan

additional10fans.ThetechnicianhadtologontotheEnergratedComputerSystemto

maketherequiredsoftwarechangestoallowallfanstobeturnedoff. Thiswas

completedat12:51.

Atthispointtheroofwasdown. Barricadeswereplacedatallfieldentrancesandstaffweretoldtoremainintheconcourseareaundertheconcreteroof.

Onesupervisoralongwithtwoworkers,werethefirstonesupontheringbeamtoassessthe

damage.Whentheyarrivedonthetopthroughthewesthatch,theynoticedsnow/ice/slush,

withaccumulationuptotheeliminatorframes.Therailingswereallstillinplaceandthedrains

wereallfrozenandpluggedwithiceandslush.Theyhadtouseshovelstoclearthedrains.When

theygottheshovelsoutoftheroofboxes,theyobserved2inchesofveryheavy,frozensnowon

topoftheseboxes.Thelidsweresoheavytheycouldbarelyliftthem.


17/82


Otherauthorizedpersonnelwentuptotheringbeamshortlyafterthedeflationwhichconsisted

ofBCPlace&PavCoemployees,architect,structuralengineers,Cityinspectors,rescue

professionals. Theircommentsincluded:lotsandlotsofsnow, asurprisingamountofsnow,

veryslippery,snowstillstuckonsomepanels,moresnowonthewestthantheeast,

cablesappearedcrooked,watersnowandiceontheseatsrightunderthehole,etc.. Some

ofthesepeoplewereabletotakephotographsofthedamageandtheroofconditionwhichgreatlyassistedtheinvestigationprocess.

Meanwhile,backinsidetheStadium,oncetheroofwasstableinitsconstructionposition,the

assessmentprocessthenkickedinandcallsweremadetobringinassessmentstaff,engineers,

riggersandsafetyprofessionalsetc.tocomeupwithanactionplan

Theabovesequenceofeventssummarizesthedatacollectedbytheinvestigationsub

committee. Itisthefoundationoftheinvestigationandhasformedthebasisforthe

causalanalysisoftheeventtodetermineoutcomesandrecommendations.


18/82


CommentaryonSequenceofEvents

AsthesnowmeltalarmscameinonthemorningofJanuary5th

,thesnowandsleet

begantoaccumulateonthefabricsurfaceoftheroof. TheStadiumtemperatureset

point

remained

at

the

lowest

possible

setting

of

10

degrees

C

and

the

internal

pressure

setpointremainedat250Pa.

ManyStaffcommentedonhowcolditwasinthestadium. Whensnowwasobserved

fallingandaccumulatingonthePlazadecks,somestaffwereconcernedenoughabout

thelackofheat,thattheywenttothecontrolroomtoinquirewhytheheatwasnot

increasedorthesnowmeltsystemturnedon. The4th

and5th

snowmeltalarmscamein

at8:17and11:01thatmorningandbothtimestheoperatorpushedthe15hourdelay

timertopostponetheactivationofthesnowmeltsystem.

Atapproximately10:30adutymanagerwenttothecontrolroomandvoicedconcernto

theoperatorbecausetherewas2inchesofwetslushysnowontheplazadecks. The

controlroomoperatorlookedattheringbeammountedcameratocheckthecondition

oftheroof. Heinformedthedutymanagerthatthesnowhadslidofftheroofandnot

toworry.(SeeEquipmentsectionphotosoftheviewsforthiscamera)

Itshouldbenotedthatat08:18,constantspeedfan#4inFanroom2wasturnedon. As

theoutsideairtemperaturewascloseto0degrees,uponstartupandforaperiodof

time,thisfanroomwouldhavebeendeliveringasignificantamountofheatedairuntil

thereturnairtemperaturecameuptothesetpointof10degreesC. Theotherfactoris

thatfan#4isaconstantspeedfanandthereforewouldhavebeendeliveringaconstant

100,000CFM(cubicfootperminute)ofairflowasopposedtotheASDfanswhichwouldonlybeoutputtingmuchlowervolumesofair.

Thelevel5dischargedamperforfanroom#2islocatedatsection10ofthestadium.

Thisistheexactstadiumsectionthattheringbeammountedcameraislocated. A

significantamountofheatedairwouldhavebeendischargedfromthisdamperwhile

thetemperaturecontrolsystemopenedthesteamvalvetoraisethereturnair

temperaturetotheminimumvalueof10degrees. Thisheatedairwouldhaverisento

heattherooffabricintheimmediatevicinityofthecamera. Thereforewhenthe

operatorsawthismeltingeffectonthesmallareaoftheroofvisiblefromthecamera,

hewasonlygettingthesmallpicture. Inrealityonlythissmallsectionoftheroofwas

sheddingsnowduetotheheatingeffectcausedbyfan#4.(Thiseffectwouldhavebeen

mirroredinFanroom#7astherewasalsooneconstantspeedfanningrunninginthis

fanroomaswell.)

Contrarytowhatthecontrolroomoperatorwasobservingthroughthelimitedview

affordedbytheringbeamcamera,themajorityoftheroofsurfacewasactually

accumulatingsignificantamountsofheavywetsnow.


19/82


EventAnalysisandDiscussion

Weather

Withminimalheatandaircirculation,theroofoutsidesurfacetemperaturewas

hovering

around

the

freezing

point.

The

weather

on

the

morning

of

January

5

th

was

comingfromanortheasterlydirection.Thenearestofficialweathermonitoringstation

wastheGVRDKitsilanoHighSchoolstation. Therecordedtemperatureshovered

around1degreeCfrom4AMtoNoon,therecordedprecipitationduringthistime

periodwas17.6mmandthewindswererelativelylightwithamaximumwindspeedof

14KPHfrom4AMto3PMonthatday.

TheStadiumwindspeedsensorslocatedatboththeEastandWestRingbeamlevelof

theroofdidnotgenerateanyhighwindwarnings(greaterthan30KPH),andnohigh

windwarningwasrecordedonEnergratedcomputerprintout. Wecansafelyconclude

thewindswerelessthan30KPH. Windsdidpickupmuchlaterintheeveningof

January5th

withwindspeedsincreasingto25KPHbetween10:00PMandmidnight.

Thereisnoevidencesupportthetheorythathighwindswereafactorinthecollapseof

theroof.

Photo#1 CamerapointsNorthWest

Steamplumeindicating

winddirectionfromthe

northeast


20/82


Acompletesetofweatherdata,sourcedfromGVRD,EnvironmentCanadacanbefound

inAppendixE WeatherData.

Snowsquallsconsistingofheavywetsnow,sleetandrainmixedwithsnowfellonthe

stadiumthatmorningandafternoon. TimelapsevideosuppliedbyTomasSvabat

23degrees.netgivesagoodpictureoftheweatherincludingtimingandmagnitudeof

snowsquallsandwinddirection. (SeeAppendixHListingofPhotographsandVideo

Clips,inCDformat)

Inaddition,evidenceindicatesthatthetemperaturedroppedbelowfreezingfora

periodoftime,attheringbeamandroofduringthemorningofJanuary5th

. Witnesses

reportedfrozensnowandiceonthelidsofequipmentboxeslocatedontheringbeam

shortlyaftertheroofwasdeflated. Photographicandvideoevidenceshowssnowand

icefrozentothefabricoftheroof.

Photo#2taken45minutesafterdeflationfromringbeam

Inadditionthereisevidencetosupportthattherewasaliquidcomponentconsistingof

waterandslushontheroofaswell. Witnesseswhowereontheroofimmediately

followingthedeflationobservedandwalkedthroughslushontheringbeamdescribing

astheconsistencyofa711slushy. Underneaththisslushwasacoatingoficethatalso

frozeandblockedtheringbeamdrainsandalsomadeitveryslippery. ACityofficial

Photo#2


21/82


indicatedhowslipperythewalkwaywasashemadehiswayfromtheEastringbeam

hatchtothewestsideoftheroof.

RoofLoading

ThestagewassetforcumulativeloadingoftheroofstructureonthemorningofJanuary

5th.

Beforewelookatloading,itisimportantthatthereaderunderstandthatthestadium

roofsupportsystemisbasedonaconstantpressureenvironment. Thisisdifferentfrom

theexampleofaninflatableexerciseball. Theexerciseballisaconstantvolume

environment.

Inthecaseoftheexerciseball,ifyousitontheball,yourweightpressingdownonthe

ballwillcausetheinternalpressureoftheballtoincrease. Thisisbecausethevolume

oftheballremainsconstant.Yourincreasedweightissupportedbytheincreasein

pressureandconsequentlytheballbecomesmorerigidwhenyousitonit.

However,intheconstantpressureenvironmentofthestadium,astheloadingonthe

roofinincreased,thecontrolsystemwillacttomaintainaconstantpressure. Asthe

loadincreasedandpresseddown,thecontrolsystemwouldbleedoffthepressure

increasecausedbyweighttomaintaintheconstantpressure. Asthereisnoincreasein

internalpressureduetoloadingoftheroof,thepressureremainsconstantasdoesthe

safetyloadmargin. Oncethesafetyloadmarginisexceededduetotheadditional

weightofsnow,theroofwillnolongerbeabletosupportitselfandwillbegintodeform

anddropinelevation.

Atanoperatingpressureof250Pascals,theroofloadsafetymarginwascalculatedto

beapproximately324tons. Thisisbasedonanevenlydistributedloadovertheentire

roofarea. (SeeAppendixBBCPlaceRoofLoadingCalculationsfordetailed

calculationsandanalysis)

Asprecipitationintheformofhighdensitysnow,sleetandrainbegantoaccumulateon

thefabricsurfacesoftheroof,theweightofthismaterialbegantoapproachthesafety

marginload.

Basedonphotographicevidence,thesnowloadontherooffabricwasuniformly

distributedovertheentireroofarea. Asdiscussedintheprevioussectiononweather

conditions,thereweretwoseparateformsofprecipitationontheroofthemorningof

thecollapse. Thefirstbeingauniformcoatingofwetsnowthateventuallyfrozetothe

rooffabric. Thesecondformconsistedofamoremobilemixtureofrainandslushthat

fellontopofthefrozenlayerofsnow. Thethreephotographsbelowillustratethe

uniformsnowcoverageontheroof.


22/82


1stof3photostakenfromapartmentoppositestadium

Thissequenceofphotosillustratesthemovementofsnowoffthepanelsastheroof

camedown.

Photo#2ofsequenceshowsastheroofdropped,snowbeginstomigrateoffsomeroof

panelsslidingintothecenterofthebowl.

Uniformsnowloading

onthemajorityofroof

anels

Snowhasnowslidoffthis

rectangularpanel

Snowhasslidoffthe

lowerpartofthis

rectanglepanel

Theremainderoftheroofis

stillevenlycoveredwithsnow

Snowbeginsto

slideoffsome

ofroofpanels

inthisarea

WaterMarkonringbeamcaused

bythespilloveroftheavalanche

contentsofwater,iceandsnow

Photo#3

Photo#4


23/82


Thirdphotoinsequenceillustratesfurthermigrationofsnowoffroofpanels.

PhototakenfromRingbeam45minutesafterdeflation

Piecesof

ice\frozen

snowbroken

awayfrom

fabric

Majorityof

easttriangle

isnowclear

Centerdiamond

panelsstillcovered

insnow

Northtrianglenow

mostlyclearofsnow

Photo#5

Photo#6 Secondarydamageto

rectangularroofpanelPilesofsnow/icethat

haveslidoff

rectangularroofpanels

downintothebowl,

theroofcableline

actedasabarrier


24/82


Astheroofloadbegantoapproachthebalancepoint,theentiretopsectionoftheroof

begantoflatten. Astheroofapproachescriticalloading,itbecomesverysoft

structurallyandsmallincreasesinloadingpastthispointfurtherexacerbatethe

deformation. Themainspeakerclusterwhichissuspendeddirectlyunderneaththe

westernsectionoftheroofwastheextraweightpullingdownthealreadyoverloaded

roof. Thiscausedatleast3diamondpanelsinthisareatobecomeinverted.

Theinvertedareabecameacollectionpointwherewaterandslushbegantodraininto

thisareacreatingapond. Shortlybeforethewestpanelwasdamaged,witnesses

observed invertedpanelsinadditiontoseeingtheroofcablesinthisareabent

downwardandwaterpouringoutofonetheroofdomevents.

Thephotographonnextpageillustrateshowthemainspeakerclusterissuspendedand

anchoredtotheroofcables.


25/82


Mainspeakerclustercablesupportanddiamondpanelsinthepond/inversionarea.

Themainspeakerclusterhangsinsidethestadiumsupportedby4cablesthatattachto

themainroofcablesjusteastofthewesttrianglepanel.

Mainspeaker

clustersupport

framecable

attachmentpoints

Roofdamper

reliefvents.

Witnesses

observed

waterpouring

outofthese

vents

indicativeof

panel

inversion.

TopofWest

trianglepanel.

Thisisthepanel

thatfailed.

MainSpeaker

clusterat15

meterposition

These4panels

withinthered

boundarywerein

distressandatleast

3ofthesepanels

wereinverted.

Avalancheor

pondtraveled

inthedirection

ofarrow

towardsthe

westtriangle

roofpanel.

Photo#7


26/82


Theoriginaloperatingproceduresforthebuildingmakereferencetoloweringthemain

speakerclustertoavoidpanelorroofinversioninasignificantevent. Byloweringthe

mainspeakerclustertotheground,theweightwillberemovedfromtheroof,reducing

theloadinginthisareaoftheroof. Thisincreasestheabilitytowithstandmoreloading

withcausingdeformation.

Thisspecificareaunderthemainspeakerclusterhasanincreasedloadcausedbythe

weightofthespeakercluster. Hence,itwilltakelessofasnowloadthanotherroof

sectionstocauseeitherdepressionorpanelinversion. Asloadingcontinuesandmore

waterandslushfallsin,thepondorinversiongrowsinsize.

OnthedayofJanuary5th

,themainspeakerclusterwassetatits15meterdefault

position. Astheroofbecameoverloaded,witnessesobservedthemainspeakercluster

atvariousheightslowerthanthedefaultsetting. Thefollowingphotographillustrates

themainspeakerclusteratthedefault15metersetting,alongwithlowerpositions

observedbywitnesses.

ThisphotowastakenfromtheEastfieldentranceshowingthemainspeakerclusterat

15meterposition.

Speakercluster15

metersor49feet

aboveturf. Thiswas

thepositionsetting

oftheclusteron

January5,2007.

Photo#8


27/82


Itisclearfromthephotographicevidencethatby12:24theloadingontheroofhad

exceededthesafetyloadmarginandtheroofbeganitsdecent. Atonepointatabout

12:24pmaphotographshowsthewestpanelinvertedatthetop. At12:25orsothe

roofwasabout50feetlowerthanitsnormalprofile.

This

photo

represents

the

normal

profile

of

B.C.

Place

at

250

Pa.

Thisphotowastakenabout20minorsobeforetheavalanche.

Pondorpanel

inversionin

thisarea

TopofVancity

officebuilding

West

Triangle

PanelTop

5

floors

ofVancity

Buildingnow

visible

Photo#9

Photo#10


28/82


Noticethedifferenceintheelevationaswellashowflattheroofisonthetopsections.

Theroofprofileinthe2ndphotoisabout50feetlowerthanitshouldbe. Thewitness

thattookthispicturedidsobecausehethoughtitwasstrangethathecouldseethe

upperportionoftheVancitytowerlocatedatQuebecandTerminal. Normallyhecould

onlyseetheflagpolefromhisapartmentwindowandthispromptedhimtobegin

takingphotos.

Oncetheweighthadaccumulatedontheroofandthepondwasallowedtoaccumulate,

itwasinevitablethatoncethepressurewasrapidlyincreased,theunstablepond

consistingofwater,iceandsnowwasgoingtomovesomewhere.

Therewasarapidincreaseinpressurecausedbyapressureovershootinthebuilding

controlsystem(RefertofulldetailsonPressureExcursion). Thissuddenincreasein

pressurecausedtherooftoregainitsnormalprofile. Atthesametime,thiscauseda

suddenandinstantmovementofaminimumof8,000to11,000lbsofwater,iceand

snowtomovesuddenlyandquicklydowntheWesttrianglepanel.(SeeAppendixD

InvertedPanelLoadingCalculations)

Thislargemassinvertedthewesttrianglepanelasittraveledwestward,causingthe

paneltodepress6to8feetlowerthannormal. Asthemassmoveddownthewest

panelitfinallyhittheinsideringbeamandSeikoClockwithsuchtremendousforce,it

tooktheroofpanelwellpastitsdesignbreakingstrength.

Theresultwasafailureintheweakestspotwhichwasafieldweldwheretheskirting

hadbeenweldedtothefabric. Thisfindingwasdeterminedbytheengineer;see

AppendixGGeigerEngineersReportData,Sept14,2007,#207813. Hadtheweld

notbeenthere,thepanelfailurewouldhavefailedinthenextweakestspot,etc. The

forcelikelywaslargeenoughtofailevenanewpanel.Thekeytothispanelfailurewas

theavalancheofsnow,waterandicewhichshouldhavenotbeenallowedto

accumulateonthesurfaceoftheroof. Itshouldalsobenotedthatarectangularroof

panelwasalsodamagedonthesoutheastsideoftheroof. Photograph#6above

clearlyshowsarippedpanel. Thismayhavebeencausedbysnowandiceslidinginward

downintothebowlastheroofdeflated.


29/82


Fiberglassfibers(rooffabricmaterial)werefoundimbeddedinthemetalhousingon

whatwasremainingoftheSeikoClockadpanel.

SeikoClockhousing Seikoclockframe

Inadditionsomeoftheinchmountingboltssecuringtheclocktotheconcretewereshearedoff. Thisgivesthereadersomeideaofthemagnitudeofthecollisionforces

thatweregeneratedwhentheavalancheormovingpondstruckboththeSeikoclock

andtheconcreteringbeam.

glassfibers

imbeddedin

damaged

metalclock

panel

Strandof

glassfiberon

Seikoclock

housing

6feethighconcrete

ringbeam

Noticehowmetalstructureis

deformedandpushedinasa

resultoftheavalanchecollision

forces. Thisiswherethe

committeeobservedinchanchor

boltsthatwereshearedoff.

Thispanelis

undamaged. Notice

howthefaceofthe

structureisflush

withtheringbeam

RemainsofSeiko

clockinternal

electronics/wiring

Rooffabricattachestoring

beamhere. Thearcgivesan

ideaofhowfardownbelow

theringbeamtheavalanche

causedthepaneltomove.

Photo#11

Photo#13

Photo #12


30/82


RoofFabric

Theengineerhadconductedextensivetestingofthefabric. PleaserefertoGeiger

Engineersdraftreportonthefindings(AppendixGGeigerEngineersReportData,

Sept14,2007,#207813).

It

is

determined

fabric

weakness

did

not

play

a

significant

role

in

the

initial

failure

of

the

panel. Themovingweightofslush,snowandicethatwasexperiencedonJanuary5/07

wouldhavebeenenoughtodamageamuchnewerrooffabric. Duringthe

investigation,theengineersharedinformationonasimilarroofdeflationincident

happenedin1982attheMetrodomeStadiuminMinneapolis. IntheMetrodome

incident,thethenoneyearoldairsupportedroofbecameloadedwithsnowandice

withsomepanelsinverted. Operatingstaffincreasedinternalpressuretoomuchand

tooquickwhichledtoanavalancheofsnowandicethatcausedroofpanelruptureand

consequentlyatotalroofdeflation. TheMetrodomeexampleillustratesthatevena

practicallynewroofcansustainpanelfailureduetomovingroofloadsofsnowandice.

BCPlaces23yearoldroofmayhavedeterioratedandevenweakenedatsomespots,

butthatwouldnothaveresultedinapanelfailureonitsown. Itwastheheavyloading

ofrain,snowandicethatcompromisedtheintegrityoftheroofstructure.

PressureExcursion

ThissectioncontainstechnicalinformationwhichisuniquetoBCPlacesroofsupport

systems. Tofullyunderstandthebehaviorsandimpactsofinternalpressureincreases,

pleaserefertoAppendixA RoofSupportPressureControlSystemsDescription.

ThecausalanalysisoftheroofdeflationatBCPlaceStadiumonJanuary05,2007points

toarapidincreaseinbuildingpressure,abovesetpointof350Pa,asasecondary,

precipitating,contributingevent.Althoughthiswasnotthedirectcauseofthedeflation

itdoesappeartohaveplayedamajorroleinthegenerationofthepanelfailure. The

computerlogsandinterviewsofcontrolroomstaffandsupervisorsalongwithvarious

witnessaccountssupportthefollowingscenario:

OnJanuary5,2007justpriortotheroofcollapse,theroofsupportsystemwasusing

bothASDandCSFcontrolsystemsforpressurecontrol. ThereweretwoASDfans

runningandtwoconstantspeedfansrunning. Thepressuresetpointwas250Paon

boththecomputerandthepneumaticpressurecontroller. Asperprocedure,therelief

controllerwassetto300Pa. Inanalyzingthecircularpressurechartrecorder,wecan

seethatthepressurewasverystablepriortostaffrealizingthattheroofwasincrisis.


31/82


PressureRecorderChartfromJanuary5,2007

EnergratedComputerConsolelocatedinthefrontareaofthecontrolroom

FullScale100%=750Pa

Inset:

Seebelowfor

detail

ThisistheEnergrated

computerusedtomakeset

pointchangesforASDfans

aswellasmonitoringand

controllingawidevarietyof

building/roofsupport

systemparameters.

Photo#14

Photo#13


32/82


HoneywellControlPanellocatedintherearareaofthecontrolroom

Whenitwasdiscoveredthattheroofwasincrisis,thecontrolroomoperatorwasinstructedtoincreasepressuresetpointto300Paandtoprepareforsnowmelt

operation. Theoperatorincreasedthesetpointonthecomputerto300Pa. Duringthe

crisisenvironmentinthecontrolroomasstafftriedtoevaluatewhatwashappening,

thenextstepoftheprocedure,namelytoincreasetheHoneywellpressurecontroller

setpointto300PatomatchthecomputersetpointandthentoraisetheHoneywell

reliefto350Patoisolateitfromthesystem,didnothappen. Thissetpointchange

requiresthattheoperatorleavetheEnergratedcomputerconsoleandgotothe

Honeywellpanelthatislocatedattherearofthecontrolroom. Inthecrisis

environmentitisunderstandablehowthisstepcouldhavebeenmissed.

WiththeomissionofchangingthesettingsontherearHoneywellpneumatic

controllers,thetwoseparatecontrolsystemsbegantointeractinaconflictingmanner.

AstheASDfansrampedupto100%speedtotryandraisethestadiumpressureto300

Pa,thepneumaticreliefcontrollerbegantoworkagainstthisactionoftheASDfansby

openingupreliefdampers. Theconstantspeedfandamperscontrolledbythepressure

controllerwerenowinrecirculationmodebecausethecontrollersetpointof250Pa

hadbeenachieved. Hencetheconstantspeedfanswerenotworkingtoincrease

stadiumpressure,insteadidlingat250Pa.

Pressure

Chart

Recorder

Honeywell

Pressure

ControllerHoneywellRelief

damper

controller

SnowMelt

delaytimers

15hoursnow

meltdelay

button

Photo#15

Magnehelic

PressureGauge


33/82


Insetofpressurechart: Pressureovershootanalysis

Asmorefanswereturnedoninpreparationforsnowmeltoperations,thepressureonly

increasedtoapproximately270to280Pabasedontheanalysisofthepressurechart

recorder. Asthebuildingpressurewasnotrespondingtothenewsetpointchangeof300Pa,andtheroofwasstillfalling,asupervisorrandowntotheTechShopwherethe

seniorcontroltechnicianwashavinghislunch. Heinstructedthetechniciantogointo

hiscomputerandincreasetheASDsetpointto400Pa. Ittookthetechnicianafew

minutestomakethesesoftwarechangestothesystem. Basedonanalysisitwas

determinedthattwofactorswereatworktocancelthissetpointchangetotheASDs.

Thefirstbeingthereliefdamperswhichwouldhavebeenopeninguptoreducethe

pressureonceitroseabove300Paandthesecondiswhenthesnowmeltsystemwas

turnedon. Itwasdeterminedthatwhentheroofsupportsystemwentintosnowmelt

mode,thesnowmeltsetpointof300Patookpriorityandcancelledthe400Pasetpoint

changemadebytheTechnician.

Meanwhilebackinthecontrolroom, directionsweregiventothecontrolroom

operatortoraisethesetpointto350Pa,themaximumpressuresettingallowedonthe

Honeywellpressureandreliefcontrollers.

TheoperatorthenchangedtheHoneywellpressureandreliefcontrollersto350Pa.

Withcomputerpressurecontroller,sinceitwasalreadyinsnowmeltmode,pressure

Pressureat270280Pajust

priortocontrollersetpoint

changeto350Pa

Pressurepriorto

crisis=262Pa

Setpoint =250Pa

PeakPressure=520Pa

LowpointofundershootwhenASD

fansbegantorespond=247Pa

Fansare

turnedoffto

deflateroof

West

TriangleFails

Numbersrepresent

percentageof750Pa.

Fullscale

70=.7x750=525Pa

Photo#16


34/82


setpointwaslockedat300PafortheASDfans. Theconditionswerenowsetupfora

largepressuresetpointovershoot.

Oncetheoperatormadethesechangesanumberofpressurerelatedeventsoccurred.

TheHoneywellpressurecontrollerbegantorespondtotheincreaseinsetpoint. Asthe

stepchangeinsetpointwas100Pa(250to350Pa)thepressurecontrolleroutput

veryquicklyincreasedfromzerooutput(fullrecirculation)to100%pneumaticoutput.

This100%signalcausedthefanroomdamperstoswitchfromfullrecirculationtonow

callingfor100%outsideair.

Simultaneously,thereliefcontrollerwhichalsohaditssetpointchangedto350Pa

begantooutputitspneumaticsignaltocloseallofthereliefdampers. Theneteffectof

theseactionscreatedarapidincreaseinpressure. ThefourASDfanswererunningat

closeto100%,thefourconstantspeedfanswerenowdrawinginoutsideairat

maximumrates. Wenowhaveeightfansdrivingthepressuretowardstheirrespective

setpoints. Asthepressureroseto300Pa,theASDfanswouldhavesloweddown,as

theirsetpointvaluewasnowachieved. Thefourconstantspeedfanscontinueddriving

thepressureupwardtowardstheirsetpointof350Pa.

Thisiswherethecharacteristicsofapneumaticsystemworkedtoamplifythepressure

overshoot. Asthepressureroseabove350Pa,thepressurecontrolleroutputwould

nowstarttodecrease. Butsinceitisapneumaticsignal,ittakestimeforthesignalto

propagatethroughthepneumaticsystemoverthelargedistancesfromthecontrol

roomtothefanrooms. Insomecasesthisdistanceis800feet. Consequentlyittook

timeforthesignaltoreachthedampersandtobegintoreducetheamountofoutside

airbeingbroughtin(thisincreasedpressure)andswitchtorecirculationmode. During

thistimelagthepressureinthestadiumcontinuedtorisewellabove350Pa.

Inparalleloperation,thepneumaticreliefcontrollerisnowsensingthepressurerising

aboveitssetpointof350Pa. Asthepressurerisesabovethesetpointthepneumatic

controlleroutputsendsasignalouttostartopeningthebanksofreliefdampers.

TypicallyduetothelocationofthereliefdampersonLevel4andattheringbeamlevel

5ofthestadium(distancesofcloseto1000feet)thetimedelayforfullyopeningthe

reliefdampersistwominutes. Whilethisdelayisineffectthepressureisstillrising.

Bythetimethereliefdampersbecameeffectiveandhaltedtheupwardpressure

overshoot,thepressurehadrisento68%onthepressurechartwhichrepresentsapeak

pressureof520Pa. Forsuchalarge100Paincreaseinpressuresetpoint,combined

withtherapidturnonofadditionalfans,thisisnotanunreasonableovershootabove

thesetpoint.

Theonlyproblemwasthesignificantroofoverloadingandsubsequentpanelinversions

thatcreatedalargeunstablemassonthewestendoftheroof. Oncethepressurewas

increased,theroofbegantoregainitsnormalprofile. Asthepressurecontinued

towardsitspeakof520Pa,eventuallytheinternalpressurewasenoughtoovercome


35/82


thedeformationoftheroof. Asthishappened,themassofsnow,waterandicebegan

tomovedownwardaccordingtotheprincipalsofgravity. Themasswasslidingfrom

paneltopanelpickingupweightandvelocityasitmoved. Theresultwastheavalanche

ofsnow,waterandicethatresultedinacatastrophiccollisionwiththeringbeam. The

rooffabricatthispointwassustainingatremendousweight,andfinallybrokenatits

weakestspotresultinginthefailureofthewesttrianglepanelandtheexplosionofthe

Seikoclock.

Oncethetearoccurred,itwastoolate. Activitiesrecappedbelowweresimplysystem

defaultreactionstothepressurelossduetoaholeintheroof,buthadnoeffectsin

rescuingthedamagedroof. Thereliefsystemhasnowfullyopenedallofthedampers,

thepressurecontrollersignalispositioningtheconstantspeedfandampersforfull

recirculationandthepressureisdecreasing. Bythetimethepressuredropsbelow300

PatheASDfancontrollernowrespondsandtheASDfansbegintospeeduptocounter

thepressuredrop.Thepressurefellbelowthesetpointreachingalowpointof33%or

247Pa. Asthepressuredroppedbelowthesetpoint,computercontrolledASDfans

reactedquicklyandbegantoraisepressure.Thepressurewasonitswaybackuptothe

setpointof300Pawhenthewesttrianglepaneltotallyfailed. Atthispointthe

pressurewasabout37%or277Pa.

Thistechnicalanalysisofthedatasupportstheconclusionthatthenotedaccidental

rapidpressurizationofthebuildingwaslikelytheresultofanovershootinthe

pneumaticdamperpressure/reliefcontrolsystem. Throughoutthehistoryofthis

building,therehavebeenseveralsimilarpressureexcursionsupwardsof100Paabove

setpointundervariouscircumstances.

Itisimportanttonote,duringthehandlingoftheroofincrisis,noStadiumpersonnel

wereflippingdifferentswitchestocausetherapidpressureincrease.


36/82


Equipment

Thecausalanalysisrevealedanumberofdeficienciesthatwererelatedtoequipment.

1.Theabilityofthecontrolroomtoeffectivelyanalyzeandseetheactualroof

conditionswaslessthanadequate. Theexistingcamera(picturebelow)located

outsideontheringbeamofthestadiumwasonlyabletoseeasmallportionofthe

rooffabriclessthan10feetupfromtheringbeam. Consequentlythecontrolroom

operatorwasunabletoobservethecumulativesnowloadingoftheroof.

RingbeamCameraatsection10(TerryFoxPlaza)

Photo#17rightpanview Photo#19 leftpanview Photo#29 centerview

Theabovearephotosoftheactualscreeninthecontrolroomthatoperatorsuseto

viewthecamera.

2.Thecausalanalysisalsohighlightedtheinabilityoftheexistingcontrolsystemto

senseadropinroofelevation. Henceastheroofbegandroppingfrom12:00to

12:30,thecontrolroomoperatorwastotallyunaware.

3.Thecausalanalysisidentifieddirectcause#2asthefailuretoincreasepressureand

effectivelyapplyheat. Twoofthekeyaspectsrelatedtocause#2wereboththe

absenceofapushedautomatedweatheradvisoryservicetonotifyoperatorsof

significantweathereventsthatcouldimpactstadiumoperationsaswellasthetotal

Ringbeam

mounted

camera

Photo#16


37/82


lackofaccesstorealtimeweatherinformation. Bothoftheseserviceshadbeenin

placeinthepast,butwerediscontinued.

4.Thecausalanalysisconductedbythecommitteeidentifiedarapidincreasein

pressureasasecondary,precipitating,contributingeventanditwasafactorinthe

generationofthewesttrianglepanelfailure. Theanalysisoftherapidpressure

increaseidentifiedbothhumanelementsrelatingtocontrolsystemsettingsaswell

ascontrolsysteminteractionsandconflictsastherootcauseoftherapidpressure

increase.

5.Themechanismtolowerthemainspeakerclusterwasnotlocatedinthecontrol

room. Inanemergencysituation,thisdelaystheresponsetimefortheoperatorto

lowerandunweightthespeakertothegroundinanextremeloadingsituation.

6.Whileitisknownthatthesnowmeltingsystemcanhandlevirtuallyanyamountof

snowandkeeptheroofclearwhenoperatedproperly,thecommitteeidentifiedthe

potentialriskofsystemfailuresthatcouldrenderthissnowmeltingsystem

ineffective. Intheearlyeighties,roofhotwaterdispersionsystemwasinstalledto

beusedincontingencysituationsforsnowremovalfromtheroof. Inadditiontothe

hotwatersystem,therewasavarietyofspecializedequipmentstoredinequipment

boxesontheroofthatwasreadyforuseinemergencysituations. Someofthis

equipmentincludedpumpsfordrainingpanelinversionsorponds,emergency

generators,snowblowersandshovelsforringbeamclearing,roofrepairequipment

andmaterialforeffectingtemporaryrepairstotherooffabric.


38/82


CrisisIdentificationandManagement

Fromthemomentthatstaffwereinformedthattheroofwasindistress,therewasa

lackofcoordinationandassessmentoftheproblem. Supervisorsandstaffrantothe

controlroom. Onesupervisorstayedatthefrontofthecontrolroomandimmediately

instructedthecontrolroomoperatortoraisethepressuresetpointto300Paandget

readyforsnowmeltsystemactivation. Theothersupervisorandaworkerwenttothe

backofthecontrolroomtolookattheMagnehelicpressuregauge,believingthatthe

problemwiththeroofmayberelatedtopressure. Oneoftheworkersleftthecontrol

roomtogooutseewhatwasgoingonwiththeroof. Hereturnedtoreportthatthere

werenumerousinvertedroofpanelsnearthespeakercluster. Atthispoint,whenit

wasidentifiedtheroofwasincrisis,multiplepartieswereinvolvedindoingtheirbestto

dealwiththesituationindependentlywithoutengaginginacoordinatedprocess.

Afterseeingthatthestadiumpressuredidnotseemtoberisingtothenewsetpointof

300Pa,asupervisorrandowntothetechshoptoinstructaseniortechnicianto

increasethesystempressureto400Paviahisshopcomputer. Unknowntothe

supervisorandthetechnician,thesettingsforthepressureandreliefcontrollerswere

adjustedforthenewcomputersetpointof300Pa. Consequentlythepressuresetpoint

initiatedbythetechnicianwasnullifiedbythereliefdampercontrolleraction.

Asstaffweredoingtheirbesttodealwithacrisissituation,thereseemedtobealackof

coordinationintheirefforts. Thisclearlyrelatestothefactthatstaffhadnothadany

formalizedtrainingrelatingtocrisismanagement. Therewasnocrisisassessment

proceduretofollow,andconsequentlytheeffectivenessoftheirwellintentioned

actionsanddecisionswasreduced.

Thepoliciesandproceduresdocumentrelatingtoroofinversionwasnotavailableinthe

controlroom. Thisdocumentwasnotalivingdocumentasithadnotbeenupdated

andstaffhadnotbeentrainedinitsapplication.

Whencontrolroomoperatorsreceivedinformationthatsomeroofpanelswere

inverted,ifalivingpoliciesandproceduresmanualwereinplace,theycouldhave

quicklylookeduptheproceduretodealwiththisproblemandidentifiedthatstabilizing

thepressureandkeepingitat300Pawasthebestcourseofaction.

TheactivitiesfortheControlroomoperatorsareroutineforthemajorityofthetime. It

isonlyperiodicallythattheoperatorsexperiencesignificanttechnicaleventsthat

requirefastdecisionmakingandactionontheirparttodealwiththeproblemorcrisis.

Acomparativejobanalogycanbemadetocommercialairlinepilots. Forthemostpart,

thejobofapilotisveryroutineandstructuredinnature. However,whenproblems

arise,pilotsareextremelywelltrainedindealingwithcontingencysituations. Pilotsrely

onspecificproceduresandpolicieswhendealingwithawidevarietyofinflight

emergencies. Theyreceivemandatoryregulartrainingsessionsthatsimulateavast


39/82


arrayofpossibleinflightemergenciesandpracticetheproceduresandactionsto

successfullydealwiththeseemergencies. Acomponentoftheirtrainingfocuseson

crisismanagementandcockpitresourcemanagementwhichtrainsthemtoworkasan

effectiveteamwithinthecockpitenvironment. Consequentlywhenrealemergencies

doarise,pilotsareverysuccessfulatdealingwiththeseemergenciesandmitigating

potentiallossoflifeordamagetoaircraft.

Overtheyearsthestadiumcontrolroomoperatorshaveexperiencedavarietyof

seriousincidentsthathavecompromisedintegrityoftheroof. Theseincidentsincluded

numerouspowerfailures,overloadingoftheroofduetosnowaccumulationandfailure

ofkeycontrolequipment.

Ifthecontrolroomoperatorsandmanagementstaffaretobesuccessfulatdealingwith

thesepotentialcrisissituationsinthefuture,theremustbeongoingtrainingand

refreshersessionsthatgivethemtheskillsnecessarytoworkasateamanddealwith

thecrisiseffectively.


40/82


Policies,ProceduresandTraining

TheInvestigationSubcommitteelookedatdocumentsrelatedtocontrolroompolicies

andproceduresandtraining. Therewerepoliciesandprocedurescoveringthevarious

aspectsofoperationsrelatingtothedaysevent. Withpoliciesandproceduresalready

inplace,itisnecessarytoexaminewhypoliciesandprocedureswerenotfollowed.

Letsfirstlookatthepoliciesandproceduresmanual,theBCPlaceControlRoom

OperationsManualwasdevelopedbackin1987. Overtheyears,whileControlRoom

hadgonethroughupgrades,therehadbeenverylittleupdatesmadetothewritten

manual. Manyofthecontentsinthemanualwerenolongerreflectingthesystemsand

operationsintheControlRoomatthetimeoftheincident. Theneedtoupdatethe

manualhadbeenrecognizedduringanemergencyevacuationexerciseinNovember

2005,sincethenthemainpolicyandproceduremanualforthecontrolroomhadbeen

removedforupdating. Thereweretwokeypprocedurescontainedinthemanualthat

wouldhavebeenmostrelevanttotheroofcrisissituationonthedayoftheincident:

PartialRoofPanelInversion,andTotalRoofPanelInversion. Unfortunatelyboth

procedureswerenotavailableinthecontrolroomastheyhadnotyetbeenrevised.

ThefollowingaretheRoofpanelinversionprocedures:

VIII21 PartialRoofPanelInversion

ControlRoomStaffwillslowlyturnonmorefans. Thenumberoffanstobeturnedonis

dependentonthesizeoftheinversionandisuptothejudgmentofthecontrolroomoperator.

(1) WatchStadiumairpressureverycarefully. DONOToverpressure(i.e.keeppressureunder300Pa.)

(2) Trytostabilizethepressurearound250Pa.(3) ReporttotheDutySupervisorimmediately

VIII22 TotalRoofPanelInversion

(1) ControlRoomStaffwillslowlyturnonallsixteen(16)fans.(2) Watchstadiumairpressureverycarefully. DONOToverpressure (i.e.keep

pressureunder300Pa.)

(3) Trytostabilizethepressurearound250Pa.(4) ControlRoomStaffwillinformalldepartmentstohavealldoorsclosed,especially

bothairlockdoors.

(5) ReporttotheDutySupervisorImmediately

Andforupdatingpurposes,somepartsoftheP&PwereremovedfromtheControl

Roomcopyofthemanual. Oneparticularsectionwhichwasrelevanttotheroof

situation,Howtodealwiththepanelinversion,wasmissinginthemanual.

Itshouldbenotedthatduringtheinvestigation,thecommitteediscoveredthatthese

procedureshadbeendevelopedbasedonthefindingsofadeflationincidentin1982at


41/82


theMetrodomeStadiuminMinneapolis. TheMetrodomeisanairsupportedstadium

verysimilartoB.C.Place. SeeRoofFabricsectionfordetailsoftheMetrodomeincident.

Basedonthelessonslearnedfromthisincident,B.C.PlaceManagementimplemented

theaboveprocedureswhenthestadiumfirstopenedin1983toavoidasimilarmishap.

Overtheyearstheknowledgethatresultedintheadoptionofthesepanelinversion

procedureshadbeenlostbyStadiumPersonnel. Asaresultwhenthestadiumstaff

werefacedwithanoverloadedroofandpanelinversions,theydidnothavethese

procedurestofollow. Iftheseprocedureswerelivingdocuments,thestaffmayhave

avoidedthenaturalinstincttoraiseinternalpressuretocombattheroofloadingand

panelinversion,buttakenthestepsoutlinedintheprocedures.

Itisnotthecommitteesintenttosecondguessthedecisionsmadeinsuchacrisis

situation. However,wewanttoillustratetheimportanceofproperlivingpoliciesand

proceduresandhowtheymayhaveassistedindealingwitharoofincrisis.

AsnowmeltprocedurehadjustbeenintroducedrecentlyonNovember15,2007.

See


42/82


AppendixFEmergencySnowMeltProcedures,Nov15,2006. Theprocedurewason

theinsidecoveroftheP&Pmanualwithastickynoteonitsayingpleaseread. When

askedwhethertheywereawareofthenewprocedure,allControlRoomOperators

interviewedrespondedyes,buttheyalsoindicatedtheywerenotexplainednor

trainedonthenewprocedure.Furthermore,someofthecontrolroomoperatorshad

notevenreceivedtrainingontheoldsnowmeltprocedures. Inaddition,therewasno

seasonalrefresherforallcontrolroompersonnel.

WhileitwasimpliedthattheSnowMeltProcedureswastocombataccumulationson

theroof,butthepurposewasneverclearlystatedforallcontrolroomstafftoknowand

follow. Itappearsanoverarchingoperationalmissionwasamiss: keeptheroofup.

Onmanyoccasions,inspiteofthewrittenpolicythatclearlyindicatesthatifitis

snowing,thebuildingtemperatureistoberaisedtoitsmaximumtemperatureof23

degreesC,theoperatorsfelteitherthat,theydidnothavetheautonomytoexecutethis

policy;orthat,theyhadseenworseweatherconditionsbefore,needtofollowthe

policywasirrelevant.

Thecommitteefoundaculturewherebothstaffandmanagementdidnotfollowthe

writtenprocedures. Theunwrittenproceduresprevailedwhenitcametothe

applicationofheatduringsnowconditions.

Hencethatiswhylackofeffectivelyimplementedpolicies,proceduresandtrainingis

therootcauseoftheroofdeflation.


43/82


CultureIssues

Organizationalcultureplayedamajorroleintheroofdeflationincident. Organizational

cultureisthepersonalityoftheorganization. Theculturecanbeassumptions,beliefs,

practicesandnormsoforganizationmembersandtheirbehaviors.Culturecanbe

difficulttoexpressdistinctly,buteveryoneknowsitsexistence.

AcloselookatthecultureofBCPlacesmaintenanceandoperationsrequiresan

impartialbutcriticalintrospection. Thereseemedtobeanunwrittenoperational

guidelinecostminimization;applyingheatwhenitisabsolutelynecessary;turningon

heatrequiresmanagementapproval. Overtime,controlroomoperatorsdefaultedto

managementdirectionswhenitcametotheapplicationofheat.

Theculturewasnottofollowprocedure,buttoseekpermissiontoapplyheat. Ithas

beenalongpracticethatlittleheatorevennoheatwouldbeapplied,aswehave

weatheredmanyborderlinesnow/sleetconditions. Thispracticeengenderedan

unhealthycultureofcomplacency:leavingdecisionmakingtoothers,henceany

responsibilitiesandconsequencesassociatedwiththedecisionbelongedtosomeone

else. Thiscultureofcomplacencycorrelateswithalowlevelofemployeeengagement

andempowerment. Engagementisthedegreetowhichworkersidentifywith,are

motivatedby,andarewillingtoexpendextraeffortfortheiremployer. Empowerment

iswhenworkersbelievetheyhaveautonomousdecisionmakingforthebestinterest

andbenefitoftheirorganization.

ThefollowingisanexamplethatillustratesthecultureexistedinBCPlace:

Atasnowrelatedeventinlate2006wheretheoperator,believingthathedidnothave

the

authority

to

turn

on

the

heat,

worked

with

staff

and

the

Event

to

get

permission

to

turnontheheat. Thisillustratestheunwrittenpolicyorculturerelatingtotheuseof

heat. Hadtheoperatornotturnedonsomeheatduringthisheavywetsnowfall,itis

likelythattheroofwouldhavebeenincrisisonthatdate. Inspiteofthewrittenpolicy

thatclearlyindicatesthatifitissnowing,thebuildingtemperatureistoberaisedtoits

maximumtemperatureof23degreesC,theoperatorsfeelthattheydonothavethe

autonomytoexecutethispolicy.

InthisdeflationincidentofJanuary507,complacencycontinuedtobeafactoras

personnelinvolvedintheoversightandoperationoftheroofsupportsystemshadlost

theirknowledgeofbasicyetcriticalinformationrelatedtotheroof. Thisincludesissues

suchasloadingandsafetymargins,knowledgegainedbyincidentsatotherair

supportedfacilitiesandkeybehaviorsofairsupportedroofsinavarietyofweather

conditions. Asaresultofthelossknowledge,alongwithverylimitedvisionoftheroof

condition,operatorsmayhavereliedoninstincts.

Itisnotuntilwerecognizethatacultureofcomplacencyexists,thatwecanthenstart

tacklingitthroughacollectivekeeptheroof upmission,effectivepolicies,

proceduresandtraining.


44/82


CausalAnalysisMethodologies

CausalAnalysisistheprocessofidentifyingdirectandindirectcausesoftheroof

deflation. TheCausalanalysisflowedoutofthecausedriversthatwereidentifiedinthe

process

that

built

the

fishbone

diagram.

FishBoneDiagram

TheFishboneorIshikawadiagram,formedthefoundationofcauseandeffectanalysis

conductedbythecommittee. Thediagramshowsthecauseofanevent. Theendresult

oreventwasthedeflationofthestadium. TheanswerstothequestionWhydidthe

roofofB.C.Placedeflatebecamethecausesthatdrovethefinalresultofadeflated

roof. Inallphasesoftheinvestigation,thefishbonediagrambecamethereference

pointortouchstoneforthecommittee.


45/82


CausalEventPathDiagram

Thefollowingisacausaleventpathdiagramthatgivesaroadmapofthepaththatled

toPanelfailureandultimatelydeflationofthestadiumroof.

West PanelFailure

Avalanche

No Roof in

Crisis actionplan!

NoRoof in Crisis

training! NoAssessment

Training

Roof

Overloaded

WithSnow, Ice

&Water

Pressure Increase

To520 Pa.

No awareness or

assessment of roofconditions!

Failure to follow

Pre-snow, Snow meltpolicy

Lack of new proceduretraining re pre-snow

procedure.

Lack ofEffective policy,procedure and

training

CultureUnwritten NO-HEAT Policy

Failure toincrease

pressure andeffecively apply

heat.

No

PhysicalRoofMonitoring

NoPhysical

RoofMonitoring

No

ApplicationOf snow-melt

Start Here

To follow the

Causal Event Path

Lack of

SnowAbatement

CausalAnalysisChart

ThefollowingCausalcharttakesthedirectandindirectcausesandidentifiesour

analysisforeachandthentherecommendedcorrectiveaction.

Definitions:

CausalFactor: Aconditionoraneventthatresultsinaneffect.

DirectCause:Thecausethatdirectlyresultedintheoccurrence.

ContributingCause: Acausethatcontributedtoanoccurrencebutbyitselfwouldnot

havecausedtheOccurrence.

RootCause: Thecausethat,ifcorrected,wouldpreventrecurrenceofthisandsimilar

occurrences.(Doesnotusuallyapplytothisoccurrenceonly,butisgenericinnatureas

itappliestoabroadgroupofpossibleoccurrences).Quiteoftensystemic.


46/82


DirectCause#1 Causeanalysis RecommendedCorrectiveAction

WestTriangle

PanelFailure.

Avalanche(caused

severetrauma)

(Unprovenbutlikely)

Possiblepreexisting

wear/damage(most

exposedandlikelythe

moststressedpanelon

entireroof)

Havetherooftechnician

conductassessmentofthe

areaimmediatelyadjacent

totheringbeam,theentire

perimeterandunderthe

skirt.Ensurerepairsare

conductedtocorrectany

damagefound.

Haveanapprovedagency

conducttestsonthe

remainingtrianglepanelsin

thebuildingthenmakeany

necessaryrepairsor

replacement.

Trainacrewinemergency

repairandmaintainarepair

planandrepairkitinthe

buildingattheroof.

Conductadetailed

assessmentoftheroofthen

developareplacement

program.

DirectCause#1 Causeanalysis RecommendedCorrectiveAction

Avalanche

Overloadedroof,severe

snow,ice&water

accumulation

Toomuchpressuretoo

fastandthesubsequent

automatedquick

pressuredropbackto

normalsettings.

FailureofEnergrated

controlsystemto

preventconflictwith

pneumaticcontrolled

reliefsystem.

Failuretoconduct

assessmentofroofin

crisis.

Lackofsnow

abatement.

Noroofincrisisaction

plan

Noroofincrisistraining

Updatepressurecontrol

systems

to

prevent

CSV

vs.

ASDoverruns.

Trainstaffandsupervisors

inroofincrisisassessment

andsafereco

joint health and safety committee report on b.c. place stadium roof

Documents