National Engineering Vulnerability Assessment of Public

Infrastructure to Climate Change

Climate Change Vulnerability

Assessment for Culverts

Agenda

• Introduction

• PIEVC Engineering Protocol

• Climate Analysis and Projections

• Project Definition

• Data Gathering and Sufficiency

• Risk Assessment

• Engineering Analysis

• Conclusions

• Recommendations

Introduction

• Who

– The study is co-funded by the City of Toronto and Engineers Canada

• What, Where, and When

– The study involves an engineering vulnerability assessment of three of the City of Toronto’s culverts; Ellesmere, Albion and Grandravine to existing and projected future climate conditions during the 2040’s time horizon

• How

– The assessment was conducted using the Public Infrastructure Engineering Vulnerability Committee (PIEVC) Protocol

• Why

– City’s objective is to proactively identify components of the culverts that have an increased risk of failure or damage due to potential climate change

Introduction

City of Toronto owns and operates over 150 large diameter culverts.

Three culverts were selected for this study:

PIEVC Engineering Protocol

• The study was conducted using Version 9 of the PIEVC Engineering

Protocol for Climate Change Infrastructure Vulnerability Assessment

(April, 2009)

• It consists of the following 5 steps:

– Step 1: Project Definition

– Step 2: Data Gathering and Sufficiency

– Step 3: Risk Assessment

– Step 4: Engineering Analysis

– Step 5: Recommendations

Project Definition – Ellesmere Culvert

• The culvert was constructed in1961

• Twin box reinforced concrete

Armour Stone

Storm Sewer Outlet

Outfall Headwall

Wingwall Concrete Twin

Box

Project Definition – Albion Culvert

• The culvert was constructed in 1964

• Corrugated steel pipe arch

Embankment

Inlet

Outlet

CSP

Buried Utility Infrastructure

Road Users/Vehicles

Pavement

Above-ground Infrastructure

Project Definition – Grandravine Culvert

• Year of construction is unknown

• Corrugated steel pipe arch

Floodplain

Channel

Pipe Arch Outlet Pipe Arch Inlet

Damaged CSP

Data Gathering and Sufficiency

• All the components were grouped into the following general categories:

• Administration/Operation

• Road

• Drainage

• Active Stream Corridor

• Natural Features

• Surrounding Area

• Utilities

Climate Analysis & Projections

• Selected a set of climate parameters describing climatic and meteorological phenomena relevant to the:

– Geographic areas of the Ellesmere, Albion and Grandravine culverts

– Potential risk and vulnerability of culverts

• Determined probability of occurrence of each climate event using available data sources (for existing/historical and future (2040’s))

High Temperature

Sustained High

Temperature in the Winter,

with snow on the ground

Heavy Winter Rain Ice Storm Tornado

Low Temperature Freeze/Thaw Freezing Rain Lightning Drought/Dry

Periods

Heat Wave Heavy Rain Heavy Snowfall Hailstorm Heavy Fog

Cold Wave Heavy 5-day Rain Blowing Snow Hurricane/Tropical

Storms

Extreme Diurnal

Temperature Variability

High Intensity Short

Duration Rainfall Snow Accumulation

High

Wind/Downburst

Climate Analysis and Projections

Climate Parameters for which the probability scores

increased from historical to future

High Temperature

Heat Wave

Heavy Rain

Heavy 5-Day Total Rainfall

High Intensity Short Duration Rainfall

Winter Rain

Freezing Rain

Ice Storm

Heavy Snow

Hurricane/Tropical Storm

Drought/Dry Period

Climate Parameters for which the probability scores

decreased from historical to future

Low Temperature

Cold Wave

Extreme Diurnal Temperature Variability

Freeze Thaw

Snow Accumulation

High Wind

• Comparison of probability scores between historical and future

Risk Assessment

• A risk assessment workshop was conducted on April 13th, 2011

• The workshop participants were from the GENIVAR team, City of Toronto staff, and the Project Advisory Committee

• In order to validate initial findings, the participants were asked to determine:

– Interactions between climate events and infrastructure components that they considered relevant to the study

– Severity of the climate event on the infrastructure component from a scale of 0 (negligible) to 7 (extreme)

Probability Scale Factors

• P = Probability of a negative event

• Our Study Team and the City of

Toronto selected Method A

Severity Scale Factors

• S = Severity of the event, given

that it happened

• Out Study Team and the City of

Toronto selected Method E

Risk Assessment

• Risk = P x S – P = Probability of Climate Event

– S = Severity of the climate event on the component

Risk Range Threshold Response

< 12 Low Risk No immediate action necessary

12 - 36 Medium Risk Action may be required

Engineering Analysis may be required

> 36 High Risk Immediate action required

In total there were 688 interactions – 53% were in the low risk category (under both existing and future conditions)

– 22% were in the medium risk category (under both existing and future conditions)

– 25% changed between low and medium risks from existing to future conditions

– None were in the high risk category

Engineering Analysis

• Engineering Analysis Results

Ellesmere Albion Grandravine

No. of interactions considered in

the engineering analysis 134 150 123

No. of interactions assessed to

be vulnerable 33 36 42

Generally, the vulnerabilities exist to the following climate events:

Heavy Rain, High Intensity Short Duration Rainfall, Heavy 5 Day

Rain, Hurricane/Tropical Storm, Freezing Rain, Ice Storm, Heat

Wave, High Temperature, Tornado, High Wind/Downburst

Conclusions

Generally, the results of the engineering analysis demonstrate that the culverts have relatively low vulnerability to potential future climate change.

Culverts studied are in relatively good condition

Many of the vulnerabilities identified relate to aspects which are not unique to culvert infrastructure systems. These have been assigned a low priority under recommendations.

Most critical vulnerabilities specifically related to these culverts:

1) Capacity

2) Embankment Stability

3) Potential Vegetation Impacts

Recommendations

• Review the flows being experienced at the culverts and compare with capacity of culverts

• Study potential for flooding upstream of the Grandravine culvert in further detail

• Review conditions of Grandravine embankment to determine capacity to withstand upstream flooding

• Review long term performance of the embankments under a range of overtop scenarios.

• Options to improve embankment stability to ensure performance during extreme floods should be considered.

Recommendations

• Review policies regarding floodplain maintenance and preventative measures (i.e. increased planting) to combat erosion. Conduct regular erosion monitoring of channel (annual or biannual)

• Utilize a “No regrets” strategy in determining prioritization of capital upgrades to culverts regardless of climate change

• Review the policies and procedures associated with the Operations personnel and how they get to the culvert and perform their duties, particularly under extreme conditions

• Continue to monitor the risks and vulnerabilities identified through the assessment, particularly as components continue to age

• Monitor the progress in climate science and revisit assessment as advances are made

Recommendations

• Preserve the high standard of maintenance and management that

the City has devoted to the culverts to this point. Implement

recommendations from Culvert Management System Review in the

following areas:

– Large Culvert Inspection

– Detailed and Minor Inspections of Large Culverts

– Maintenance/Repairs

– Reporting and Monitoring

– Control of Documents and Records

– Corrective Actions

– Management Review