HIHI IVMAA - March 2005 Lessons from the ice storm of 1998 in Québec (from Bérubé Roger and C. Houde August 3, 2003) François Gauthier, f. eng., M. Sc

IVMAA - March 2005

Lessons from the ice storm of 1998 in Lessons from the ice storm of 1998 in QuébecQuébec(from Bérubé Roger and C. Houde

August 3, 2003)

François Gauthier, f. eng., M. Sc.

Environmental project leader

Hydro-Québec TransÉnergie

Le Code de gestion des pesticides - Les implications pour TrLe Code de gestion des pesticides - Les implications pour TransÉnergieansÉnergie

22

A historic stormA historic storm

The climatic event of the century in Montreal area

Occurs once in 450 years

Duration of 80 hours vs an average of a few hours (12 – 17 times a year)

100 mm of ice vs 40 mm in 1961 25 mm in 1997


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A heavy impactA heavy impact

A major impact on our customers January 5, 1997 ice storm

180 000 customers January 5, 1998 ice storm

1 400 000 customers

Thousands of trees destroyed or damaged

1600 repair crews from a hundred companies (600 pruning) for over a month


44

Ice storm impactIce storm impact

Especially a vegetation management Distribution problem


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Service Interruptions – Jan 97 vs Jan 98Service Interruptions – Jan 97 vs Jan 98

(number of customers)

-

500 000

1 000 000

1 500 000

5 6 7 8 9 10 11 12 13date

Jan 97 Jan 98


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DiagnosisDiagnosis

Causes of distribution network failure:

Design specifications exceeded (54 %) (zones of low density vegetation) Issue: More robust network

Falling trees and branches (46 %) (zones of medium and high density vegetation) Issue: Controlling vegetation


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Hydro-Québec orientationsHydro-Québec orientations

Restore service in less than a week for most customers

Be able to handle an ice storm that recurs once in 100 years

Make priority lines more robust

Optimize solutions between Transport and Distribution


88

A robust networkA robust network

Reinforcement program

Zones > 45 mm of freezing rain (100 years prob.)

Raise design criteria on priority lines

Failure sequence: Wire detaches Cross arm detaches Pole breaks

Emergency plan


99

Controlling vegetationControlling vegetation

Trees increase network vulnerability to climatic extremes


1010


Effects of climate

Wind: Wind strength increases by the cube of wind speed

An 80 km/h wind is 8X stronger than a 40 km/h wind

Ice: Weight of ice increases by roughly the square of its thickness

25 mm of ice is 25X heavier than 5 mm


1111


Key facts

Falling trees and branches largest cause of outages Average of 50 %

Similar impacts of freezing rain, strong wind and wet snow

Vulnerability to less severe freezing rain Damage to trees starts at 15 mm Systematic damages from 25 mm


1212



1313


Actions targeted Cut overhanging branches

Urban mostly Remove hazardous trees

Urban and forested Priority according to

Probable thickness of iceStrategic importance of lines

Better diagnostic of problem trees


1414

Controlling vegetation – Forested areasControlling vegetation – Forested areas


1515


Can tree-related outages be prevented ? Over 80 % caused by falling trees and

branches Species

Aspens, birchs, fir, silver and red maple 66 % of outages preventable 75 % acceptance by customers


1616


Budget increased fron 23 to $40 million/yr in distribution 100 000 tress cut or overhang removed per year

Planning improved Including vulnerability reduction objectives

Skills reinforced Team of internal specialists hired

Effects on contractors More stability ISO 9002 required


1717


Agreements made with municipalities Shared objectives

Management Information improved Cost control

ISO 14001 applied to operations Agreement of owners required


1818

Conclusions for vegetation managersConclusions for vegetation managers

Distribution network:

Plant the right tree at the right place

Do the required maintenance on trees

Plan for the improbable

Don't hesitate to call for help when needed

Documents

HIHI IVMAA - March 2005 Lessons from the ice storm of 1998 in Québec (from Bérubé Roger and C. Houde August 3, 2003) François Gauthier, f. eng., M. Sc