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. Environmental project leader Hydro-Québec TransÉnergie

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 2 A 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 mm in 1997

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 3 A heavy impact A major impact on our customers January 5, 1997 ice storm customers January 5, 1998 ice storm customers Thousands of trees destroyed or damaged 1600 repair crews from a hundred companies (600 pruning) for over a month

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 4 Ice storm impact Especially a vegetation management Distribution problem

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 5 Service Interruptions – Jan 97 vs Jan 98 (number of customers)

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 6 Diagnosis 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

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 7 Hydro-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

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 8 A 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

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 9 Controlling vegetation Trees increase network vulnerability to climatic extremes

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 10 Controlling vegetation 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

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 11 Controlling vegetation 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

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 12 Controlling vegetation

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 13 Controlling vegetation Actions targeted Cut overhanging branches Urban mostly Remove hazardous trees Urban and forested Priority according to Probable thickness of ice Strategic importance of lines Better diagnostic of problem trees

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 14 Controlling vegetation – Forested areas

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 15 Controlling vegetation 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

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 16 Controlling vegetation Budget increased fron 23 to $40 million/yr in distribution 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

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 17 Controlling vegetation Agreements made with municipalities Shared objectives Management Information improved Cost control ISO applied to operations Agreement of owners required

HIHI Le Code de gestion des pesticides - Les implications pour TransÉnergie 18 Conclusions 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