GHL Consultants Ltd. - Evacuation - Time To Go

Evacuation – Time To Go
Presenters
Frankie Victor, EngL, BCQ
Jun H. Kim, BASc, EIT
GHL CONSULTANTS LTD
Building Codes and Fire Science
950 – 409 Granville Street
Vancouver, BC V6C 1T2
Phone 604 689 4449
Fax 604 689 4419
www.ghl.ca
GHL CONSULTANTS LTD
BOABC – May 27, 2014
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This presentation is conceptual and for educational
purposes only. GHL takes no responsibility for application
of any concepts or interpretations in this presentation to
specific projects unless specifically retained for that project.
This presentation is intended to be presented by GHL and
these slides must not be considered complete or
exhaustive.
This presentation is a copyright of GHL Consultants Ltd and
all rights are reserved.
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Copyright and Limitations
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To know and understand the Code.
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To know and understand the fire science behind the Code.
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To assist in correct application of the Code.
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To develop new solutions based on fire science to enable creative safe buildings.
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To understand the needs of the client and of the Authorities and First Responders.
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GHL’s Role
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7 Engineers, 4 with Master’s degrees in fire science
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1 Architect
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4 Certified Professionals (CPs)
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2 former Building Officials
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4 Building Code Qualified (BCQ)
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GHL Team
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CP Committee (David Graham)
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APEGBC Building Code Committee (John Buscemi) 
BC Building Code Appeal Board (Frankie Victor)
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City of Vancouver Building Bylaw Appeal Board (Teddy Lai)
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BC Building Code Interpretation Committee (Teddy Lai)
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Building Code Committee Work
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Building Code Approach To Risk
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Code compliance ≠ no risk.
Code compliance = risks at acceptable level.
Failure will occur:
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Limit it to an acceptable level.
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Buildings are subject to risks:
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Building Code’s Building
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Maximum travel distance
Exits at full capacity Minimum ceiling height (2100mm)
Minimum access to exit width (1100mm corridors)
6m dead‐ends in public corridors
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The Building Code’s ‘building’ has:
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Building Code’s Building
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High‐hazard industrial  ‐ 5m = 25m
Sprinkler*  + 15m = 45m
Service space  + 20m = 50m
Open air storage garage  + 30m = 60m
Perimeter exits 60m apart  unlimited travel distance
Public corridor**  travel distance x 2
“Mall” corridor  + 75m = 105m (50% of occupants)
* Does not apply to high-hazard industrial occupancies
** Does not apply to “mall” corridors
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Base = unsprinklered floor area, 30m travel distance
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Building Code’s Building
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Example ‐ 45m travel distance, 2 exits, 2.1m ceiling height.
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Geometry – dimensional and spatial features of the space.
Demographics – characteristics of occupants; mobility.
Psychology – potential occupant behaviour in fires.
Tenability – visibility, breathability, toxicity, heat.
The following presentation focuses primarily on Geometry, which can be expressed in terms of time.
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Elements of Evacuation
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Geometry – Travel Distance
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Travel distance translates to time to walk across the room.
 All else being equal, increasing travel distance simply increases time to evacuate.
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Pathfinder is an agent-based emergency egress simulator developed
by Thunderhead Engineering Inc. It utilizes the floor layout, occupant
load and predictable elements of occupant behaviour as input to
simulate the movement time. The simulator has been well validated
through comparison to hand calculations, real life experiments and
other software.
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Geometry – Travel Distance
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Geometry – Exit Capacity
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Exit capacity (width) translates to time to pass through a corridor, door or down a stair. 13
Geometry – Exit Capacity
Same floor area. Same occupant load.
Increased exit capacity = reduced time.
1828mm
914mm
1828mm
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914mm
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Geometry – Exit Capacity
4 x 914mm = 3656mm
2 x 1828mm = 3656mm
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Increasing number of exits without increased aggregate width has no impact.
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Geometry – Exit Capacity
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Occupant load determines queuing time.
Higher occupant load / longer queue / increased time.
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Geometry – Exit Capacity
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Same exit capacity. Same number of exits.
Higher occupant load = increased time to egress.
1.2m2/person
120 persons
1.2m2/person
180 persons
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Geometry – Exit Capacity
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Same exit capacity. Same occupant load.
Smaller floor area = shorter travel distance.
Equal time to egress.
10m x 10m
60 persons
15m x 15m
60 persons
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Geometry – Configuration of Exits
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The Building Code’s factors for exit capacity are a simplified method of determining time to pass through a corridor, door or down a stair.
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Geometry – Configuration of Exits
4 x 914mm = 3656mm
2 x 1828mm = 3656mm
Effective width
= 4 x (914mm-300mm)
= 3536mm
Effective width
= 2 x (1828mm-300mm)
= 3596mm
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Reduced total effective width = increased time to egress.
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Geometry – Configuration of Exits,
Pinch Points and Obstructions
Elements that hinder egress by creating pinch points or reducing capacity of access to exit:
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Vestibules at exits (interconnected floor space).
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Use of entry for ticket collecting, security, displays.
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Retail anti‐theft equipment.
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Turnstiles.
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Etc.
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Geometry – Ceiling Height
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Corridor 1100mm x 2100mm / Travel distance 45m
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Corridor 9000mm x 4000mm / Travel distance 105m
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Relationship between ceiling height, or volume of space, and time to egress is codified in Sentence 3.4.2.5.(1):
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Geometry – Ceiling Height
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Ceiling height translates to time before smoke descends to head level.
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Geometry – Ceiling Height
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Demographics
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Occupants with locomotive disability are considered in the average occupant travel speed. 25
Psychology
 True “panic” is mostly a myth per studies and expert opinion.
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R.F. Fahy, G. Proulx. ‘Panic’ and human behaviour in fire. (2009)
 Not necessary to consider in most timed egress analyses.
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 Human behaviour is predictable….and unpredictable.
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Psychology – Human Behaviour
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Behaviour upon alert to a hazard depends on occupancy:
 Nightclub – unfamiliar, dark, crowded, impaired, noisy.
 Home/work – familiar, sense of ownership, protective of others.
 School – familiar, additional preparedness, leadership.
 Weather, gender, commitment to a task, alone or in a group, focal point/leader.
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Human behaviour can be predicted to a degree:
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Psychology – Human Behaviour
Not necessary to try and predict behaviour prior to movement provided comparison is of the same:
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People
Space
Conditions
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Psychology is independent of timed egress analysis.
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What is panic? An overwhelming fear, with or without cause, that produces an irrational response and may spread through a group.
When do people panic? When they can see no way out of a situation.
When does it matter? When it causes action without assessment of safety What do people mean when they say panic? What do building officials mean when they say panic?
Real panic in an emergency is rare; experts considered it a myth since about 1970…but the movies and news channels like it.
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Psychology - Panic
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Psychology – Timed Egress Analysis
Timed egress analysis is a comparison of the measurable elements of evacuation. (SFPE Handbook 4th Ed.)
Required Safe Egress Time (RSET)
Margin of Safety
Evacuation Time
Pre‐movement
Response
Recognition
Alarm
Movement
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Available Safe Egress Time (ASET)
Detection
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Psychology – Timed Egress Analysis
Available Safe Egress Time (ASET)
Margin of Safety
Movement Time
Detection / Alarm
Alert stage can be adjusted by detection (smoke detector activates sooner than sprinkler)
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Required Safe Egress Time (RSET)
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Upper Layer Height
Visibility
Heat flux / Temperature
Toxicity
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Tenability
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Tenability
 Zone Model: Upper layer height
 Simpler spaces
 CFD Model: Tenability parameters
 3D complex spaces
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Two types of computer models are used to gauge tenability:
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Where a straight comparison to Building Code scenarios doesn’t tell the whole story:
 Don’t meet cumulative exit capacity in an interconnected floor space.
 Using open stair for egress.
 Converging egress routes.
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Tenability
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Elements of Evacuation
 Geometry – dimensional and spatial features of the space.
 Psychology – potential occupant behaviour in fires.
 Tenability – visibility, breathability, toxicity, heat.
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 Demographics – characteristics of occupants; mobility.
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Hand Calculation
 First occupant to reach door (t1) + time to queue at door (t2)
OR
 Last occupant to reach door (t3)
Time to commence movement is not considered; assumed to be the same for Building Code and actual scenarios.
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Time to egress is the time for either:
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Hand Calculation
Travel Distance
Exits
Occupant Load
Assumption
Building Code Scenario
Alternative Solution
45m
60m
2 x 914mm door
2 x 914mm door
2 x 914 ÷ 6.1 = 300
2 x 914 ÷ 6.1 = 300
Nearest person 5m from exit
Furthest persons 45m from exit
Nearest person 5m from exit
Furthest person 60m from exit
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Example: Comparing Building Code and alternative solution
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Hand Calculation
Building Code Scenario
5
t 1*
t2
t3
t
2
1.1
300
0.914 0.3
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Alternative Solution
4.5
1.32
1.1
5
185
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2
1.1
4.5
300
0.914 0.3
1.32
60
1.1
185
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t1 t2 185 4.5 189.5
t1 t2 185 4.5 189.5
189.5s
189.5s
*assumed 5m for nearest occupant to an exit. This may vary depending on floor layout.
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Queuing (t2) is the limiting factor, hence 15m extra travel distance does not contribute to added evacuation time.
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1.
2.
3.
4.
5.
Egress via Open Stair.
Cumulative Exiting (interconnected floor space).
Egress from Two Storey Dwelling Unit.
Converging Egress (Department store travel distance).
Parkade 70m Travel Distance.
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Project Examples
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Example 1 – Egress via Open Stair
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Single exit and open egress stair.
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Sentence 3.4.2.1.(1) ‐ at least two exits required
Building divided into two storey suites each served by one exit from upper storey.
Travel distance and exit capacity met by exit stair. Open stair provided second egress route.
Timed egress, smoke model to confirm tenability.
Additional features included smoke detection for early alert.
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Example 1 – Egress via Open Stair
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Example 2 – Cumulative Exiting
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Sentence 3.4.3.2.(6) ‐ Exit stairs serving interconnected floor space based on cumulative occupant load.
Cumulative exiting not met.
Used convenience stair leading to exit on 1st storey as a means of egress.
Timed egress, smoke model to confirm tenability.
Additional features included smoke detection and smoke exhaust to keep open stair tenable.
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Example 2 – Cumulative Exiting
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Example 3 – Egress from Two Storey
Dwelling Unit
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Sentence 3.3.4.4.(2) ‐ describes egress doors in multi‐
level dwelling units at both the upper and lower storeys.
Egress door was not provided at the upper storey
Timed egress confirmed increased egress of 3 seconds.
Concern was tenability at route from upper storey.
Smoke model confirmed tenable conditions.
Draft stop was necessary.
Additional features included smoke alarms for early alert, emergency lighting linked to smoke alarm.
Fire alarm annunciation – both storeys at lower.
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Example 3 – Egress from Two Storey
Dwelling Unit
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Back-of-house Corridor
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Example 4 – Converging Egress
Mall Corridor
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Clause 3.4.2.5.(1)(d) ‐ 50% of occupants exit via mall corridor with travel distance of 105m.
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Rear corridor converged with mall corridor.
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Used mall corridor as a means of egress for 100% of occupants.
Timed egress, smoke model to confirm tenability.
Additional features include passive smoke venting to maintain tenability.
Code compliant solution = tunnel out of the building. Are people willing?
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Example 4 – Converging Egress
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Example 5 – Parkade 70m Travel Distance
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Sentence 3.4.2.5.(1) ‐ prescribes 45m travel distance.
Increased travel distance from centre areas.
Increased total exit width (extra doors).
Low occupant load eliminated queuing at exits.
Timed egress.
Additional features include exit signage, increased light levels.
Scenario
1. Code Minimum using full door capacity
2. Proposed Scenario
Number of Occupants
per Exit (persons)
Maximum
Travel
Distance (m)
Time to
Evacuate
(sec)
149
45
219
54
70
110
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Example 5 – Parkade 70m Travel Distance
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Occupancy
BC
IBC
NFPA 101
Assembly
45m
76m
76m
Care
45m
76m
61m
Business / service
45m
90m
91m
Residential
45m
76m
61m
Retail
45m
76m
76m
25/45/45m
23/76/120m
30/122/unlimited
Industrial F1/F2/F3
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Comparison of BC to IBC and NFPA 101
(sprinklered)
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Building Code limits ‐ travel distance, ceiling height, exit capacity ‐ define a space, create a scenario.
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Real‐life scenarios are compared to Building Code scenario.
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Human behaviour is predictable / unpredictable.
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Can reduce detection / alert stage by smoke detection (operate earlier than sprinklers).
Can ‘buy time’ by increasing ceiling height or exit capacity.
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Summary
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GHL CONSULTANTS LTD
950 – 409 Granville Street
Vancouver, BC V6C 1T2
Phone 604 689 4449 Fax 604 689 4419
Email [email protected] / [email protected]
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Questions?
Web www.ghl.ca
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