www.jacobs.com | worldwide

The Next Generation of Seismic Vulnerability AnalysisBellevue’s Iterative, Probabilistic, Risk-Based Evaluation

May 3, 2019 – Doug Lane, PE, and Matt Maring, PE

Presentation Overview

• Safety Moment

• Project Approach Overview

• Bellevue Water System Overview

• Seismic Risks and Threats

• Geotechnical Seismic Analysis

• Evaluation Approaches and Progress

• Next Steps

2

Safety Moment – Earthquake Self Protection

3

Project Approach Overview

Project Goals and Priorities

Characterize water system seismic threats

Identify vulnerabilities and potential customer impacts

Determine improvements needed to mitigate risks

Develop level of service goals and implementation plans

5

Seismic Vulnerability Assessment Approach

Prioritize

Improvements

Establish

(Revisit)

LOS Goals

Identify and

Evaluate

Improvements

Restoration

and Economic

Analysis

Customer

Impacts

Existing

System

Vulnerability

Geotechnical and

Seismic Data

Evaluation

Criteria and

Methodology

Data Collection

and Review

Project

Chartering

6

Bellevue Water System Overview

Bellevue Water Service Area

• 150,000+ Population

• 140,000+ Jobs

• 13 Regional Water

Supply Inlet Stations

• 69 Pressure Zones

• 24 Storage Tanks

• 22 Pump Stations

• 148 PRV Stations

• 620 Miles of Pipe

• 20-1440 ft Surface

Elevations

8

Bellevue Water System Hydraulic Profile

9

Seattle Public Utilities Regional Supply System

• Cedar and Tolt River

Surface Water Supplies

• Cedar Eastside Supply Line

• Tolt Eastside Supply Line

• Wholesale water supply to

Bellevue and other regional

retail supply systems

10

Seismic Risks and Threats

Pacific Northwest Faults and Bellevue Risks

12

• Cascadia

Subduction

Zone (CSZ)

• Seattle

Fault

Zone (SFZ)

• South

Whidbey

Island

Fault (SWIF)

Cascadia Subduction Zone Earthquake

• “The Big One”

• Magnitude 9.0

• ~500 year event

• Longer (~3 minutes) duration

• Pacific Ocean epicenter

• Broad regional impacts

(U.S. Geological Survey)

13

Seattle Fault Zone Earthquakes

• The actual “Big One”?

• Magnitude 6.6 (800+ year) to

Magnitude 7.2 (4,000+ year)

• Short duration

• Shallow fault

• Epicenter near or

under Bellevue

• Severe localized

impacts

14

Geotechnical Seismic Analysis

Peak Ground Acceleration (PGA)

Cascadia Subduction Zone

Mw 9.0

Seattle Fault Zone East

Mw 6.6

16

Liquefaction and Subsidence Risks

Cascadia Subduction Zone

Mw 9.0

Seattle Fault Zone East

Mw 6.6

17

Landslide and Slope Stability Risks

Cascadia Subduction Zone

Mw 9.0

Seattle Fault Zone East

Mw 6.6

18

Evaluation Approach and

Progress

Facility Hazus Vulnerability Analysis

20

Compare current facility to code requirements

Select Hazus fragility curve corresponding to “code level”

Overlay predicted seismic ground motions

Evaluate damage probabilities based for use in multi-break modeling analysis

Facility Hazus Vulnerability Analysis

21

Pipeline ALA Vulnerability Analysis

22

Identify location, material, and size of pipes via GIS

Apply appropriate ALA fragility equation based on pipe classification

Overlay predicted seismic ground motion and displacement

Evaluate leak and break probability for use in multi-break modeling analysis

Pipeline ALA Vulnerability Analysis

23

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 12 24 36 48 60

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bab

ility

of

Pip

e F

ailu

re

Tota

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reak

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eak

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Permanent Ground Deformation (inches)

Probability of Failure of DI Pipe

Leaks and Breaks per 1,000ft Probability of Failure of 100 ft pipeline

Seattle Fault Zone East – Pipe Failure Distribution

Probable Pipe Break Counts

by Analysis Area

Combined Probable Pipe Breaks and

Leak Counts by Analysis Area

24

Seattle Fault Zone East – Pipe Failure Probabilities

Pipe Leak

Probabilities

Pipe Break

Probabilities

25

Single Pipe Failure and Criticality Analysis

Number of Valve Closures Required

for Pipe Failure Isolation

26

Single Pipe Failure and Criticality Analysis

Demands Supplied below 30 psi

during Pipe Breaks Events

27

Single Pipe Failure and Criticality Analysis

Demands Supplied Below 30 psi

during Pipe Break Isolation

28

Monte Carlo Scenario Development and Modeling

Model Scenario Development

Hydraulic Model

Scenarios Analysis

Service Impacts

and Trends

29

Monte Carlo Simulation Development

Methodology

• Custom Python script developed

to simulate scenarios

• Pipe breaks and leaks based on

ALA probability of occurrence

• Facility status based on probability

of damage from Hazus

• 10,000 simulations for use in

multi-break modeling analysis with

Optimatics

• Compared damage results to

mean expected values by system

subarea to confirm results are

“helpful”

30

Next Steps

Next Steps

• Multiple Break and Failure Impacts Analysis and Results

(All Elements, Iterative, Probabilistic, Monte Carlo Model Evaluations)

• Projected Customer and Economic Impacts

• Restoration Strategies and Service Recovery

• Improvement Alternatives and Benefits Analysis

• Levels of Service

and Cost-Benefit

Analysis

• Improvement

Recommendations

and Planning

32

Core Team Acknowledgements

33

City of Bellevue

• Andrew Lee

(now Seattle Public Utilities)

Jacobs

• Don Ballantyne

• Kateryna Gomozova

• Jennifer Henke

• Kimberly Lawrence

• Enoch Nicholson

• Menzer Pehlivan

Shannon and Wilson

• Bill Perkins

• Ali Shahbazian

Optimatics

• Joshua Cantone

Questions and Discussion

www.jacobs.com | worldwideMay 9, 2019

© Copyright Jacobs

The Next Generation of Seismic

Vulnerability AnalysisBellevue’s Iterative, Probabilistic, Risk-Based Evaluation