Assessing the Seismic Risk of Water Systems, Application of AWWA J-100

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Overview

• Introduction

• Seismicity and earthquake hazards

• Facility vulnerability

• System assessment – Portland

– Seattle

• Restoration and resiliency

• Conclusions

Water System Seismic Risk Modeling

• Seismic risk assessment of water systems developed over last 25 years

• Pushed along by Loma Prieta 1989, Northridge, 1994, and Kobe 1995

• SVA’s following 9/11

• 2011 Christchurch New Zealand and Japan/Tohoku - 40+ days water system outage

• Oregon Resilience Plan – February 2013 similar scenario based approach – focuses on Cascadia Subduction Zone scenario

AWWA J-100, Risk and Resilience Management of Water and Wastewater Systems

• Introduced in 2010

• Focus on security vulnerability with discussion on natural hazards

• 2016 version – Integrated Analysis of Natural Hazards, Nonmandatory Appendix 4

• Addresses earthquake, hurricane, tornado and flood, methodology applicable to all hazards

Oregon Resilience Plan

System Function

Event

Occurs

0-24

hours

1-3

days

3-7

days

1-2

weeks

2-4

weeks

1-3

months

3-6

monts

6-12

months

Potable water availalble at supply source XMain transmission faciliites, pipes, pump

stations and reservoirs operational XWater supply to critical facilities available XWater for fire suppression at key supply

points XWater for fire suppression at fire hydrants XWater available at community distribution

centers/points XDistribution system operational X

Desired time to restore component to 80-90% operational

Desired time to restore component to 50-60% operational

Desired time to restore component to 20-30% operational

Current state (90% operational) X

Hazard Quantification

• Scenario based • Groundmotion

• PGA, PGV, Spectral

• Spectrum

• Liquefaction probability

• Lateral spread PGD

Component Vulnerability/

Fragility • Published • Empirical • Test data • Analytical

Component Impacts

• % replacement cost

• Functionality/ reduced capacity

• Outage time

System Analysis • Functionality/

capacity • Restoration

time • Capacity

during restoration

Societal Impacts/ Business Interruption

• Daily outage per capita $ • % Gross regional product • Business specific losses

System Risk Analysis Methodology

Improve Resiliency • Mitigation • Recovery

Approaches • Emergency

Response • Cost, Schedule

Performance Goals

• Various system functions

• Immediately following event

• Outage times

Risk = Frequency x Vulnerability x Consequence

• Frequency of hazard event – Probability of occurrence in 50 years 10%, 5%, 2%

– Return period – 500, 1,000 or 2,500 years

– Lower probability results in larger intensities

• Vulnerability when subjected given intensity

• Consequence of failure – Loss of function

– Cost or repair

– Cost resulting from outages

Risk Based

• Magnitude – Richter or Moment Magnitude

– Measure of energy release

– 32 times more energy for increase of 1

• Peak ground acceleration (PGA) % of gravity

• Permanent ground deformation (PGD) - inches

Earthquake Terminology

Probabilistic Hazard - Shaking

• USGS ground motions 2% in 50 years

• IBC • ASCE 7 • AWWA D100

Seattle Fault, M6.7 Scenario

Deterministic Hazard - Shaking • Based on selected scenario

with associated return period • Maps estimated ground

motions for a given event, not probabilistic ground motions

• Does not overestimate damage

• Shaking is calculated using attenuation relationships

• Recommend using multiple scenarios with range of return periods

• Scenarios available from the USGS

Peak Ground

Acceleration

Magnitude 6.7

Modeled

fault I

G

D

Earthquake Hazards

• Shaking – PGA, PGV, spectral

– PGA – Northridge 80 x gravity

• Permanent Ground Deformation (PGD) – Tectonic uplift/subsidence

– Fault offset

– Settlement

– Liquefaction

– Lateral spread

– Lurching

– Landslide

Liquefaction

San Fernando

Earthquake,

1971

Philippines, 1990

Costa

Rica,

1991

Liquefaction

Occurs due to shaking

Soil particles consolidate

squeezing out water

Water pore water pressure

increases reducing friction

between soil particles

Soil becomes a viscous liquid

Costa Rica, 1991

Consolidated

sand grains

Loosely packed

sand grains

Liquefaction – Lateral Spread

• Movement is perpendicular to pipe (A)

– Pipe can accommodate some bending

– Segmented pipe will separate at joints, shear and bend

• Movement parallel to pipe (B)

– Segmented pipe will pull apart at one end, and crush at the other

A

B

Hazard - Mapping

• Liquefaction susceptibility and landslide mapping often available from the state, DNR, DOGAMI, etc

• PGD mapping is not available

Modeled

fault I

G

D

Component Vulnerability

• Assess each system facility

• Estimate actual performance for scenario

• Understand damage state – Likelihood of Failure

– Functionality

– Recovery

– Recovery cost

• For specific earthquake

• For hazards

Buckled Steel

Tank. Northridge

Earthquake, 1994

Resources for Developing Fragilities

• HAZUS - FEMA

• ASCE Technical Council on Lifeline Earthquake Engineering

• American Lifelines Alliance

• MCEER, MAE, PEER Centers of Excellence

Burst cast iron pipe. Kobe 1995

Fragility Curves from HAZUS

Fragility Curve Development

• Date of design/building code – E.g. – improvements following 1971 San Fernando

– Progression of AWWA D100 seismic requirements

• Seismic zone designed to – Oregon increased in early 1990s

• Analysis – Capacity/demand

ratios

– Estimate damage when exceeded

Burst Wire-Wrapped

Tank, Purissima Hills,

Loma Prieta, 1989

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 10 20 30 40 50

Rep

air

Rate

(re

pair

s/1

,000 f

t)

PGV (in/sec)

ALA Pipeline Damage Relationships

Repair Rate/1000 feet = K1 * (0.00187)* PGV

ALA Repair Rate - PGD

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0 10 20 30 40 50

PGD (inches)

Rap

air

Rate

(1,0

00 f

t) CIP

DIP

Steel

Repair Rate/1000 feet = K2* (1.06) * PGD0.319

CIP

DIP

Steel

CCP

• Using GIS, pipelines are overlaid on hazard layers

• PGV is “related” to pipe • PGD is “related” to pipe

in liquefaction areas • Pipe breaks and leaks can

be calculated within GIS • Breaks and leaks can be

calculated by pressure zone

ALA Pipe Damage Relationships K Values

Material Joint Type Soils Diameter K1 K2 Cast iron Cement All Small 1.00 1.00 Cast iron Cement Corrosive Small 1.40 Cast iron Cement Non-corrosive Small 0.70 Cast iron Rubber gasket All Small 0.80 0.80 Cast iron Mechanical

restrained 0.70

Welded steel Lap-Arc Welded All Small 0.60 Welded steel Lap-Arc Welded Corrosive Small 0.90 Welded steel Lap-Arc Welded Non-corrosive Small 0.30 Welded steel Lap-Arc Welded All Large 0.15 0.15 Welded steel Rubber gasket All Small 0.70 0.70 Welded steel Screwed All Small 1.30 Welded steel Riveted All Small 1.30 Asbestos Cement Rubber gasket All Small 0.50 0.8 Asbestos Cement Cement All Small 1.00 1.00 Concrete w/Stl Cyl. Lap-Arc Welded All Large 0.70 0.60 Concrete w/Stl Cyl. Cement All Large 1.00 1.00 Concrete w/Stl Cyl. Rubber gasket All Large 0.80 0.70 PVC – C900, C905 Rubber gasket All Small 0.50 0.80 PVC – C909 (1) Restrained All Small 0.15 Ductile Iron Rubber gasket All Small 0.50 0.50 Ductile iron (1) Restrained joint All Small 0.25 Ductile iron (1) Seismic joint All Small 0.15 HDPE (1) – C906 Fused All Small 0.15

Added since ALA published

System Assessment

• Workshop setting – experts – GIS showing facility and pipeline

functionality

• Connectivity model/system probabilistic assessment – spreadsheet

• Hydraulic model – EPANET

– Academic models

– Negative pressure issues with many pipe failures

City Center

Mt. Hood

Bull Run Watershed Columbia

River

Powell Butte Reservoir

Groundwater System

Willamette River

Sandy River Landslide Area

Bull Run Watershed - some

components built in early 1900’s

Transmission 3 – 40 km conduits

Columbia Well Field – built in 1980’s

Treatment - chloramination, pH

adjustment

Distribution – primarily cast iron

Portland Water Supply System

Lusted HillTreatment

Facility

TR 3

TR 2

TR 4

BR 3

BR 2 & 4

LND 3

LND 2 &4

LND

ALL

Headworks

Building

WatershedAbbreviations:CD = Conduit TR =Trestles

BR = Bridges LND =Landslide

CD 2

CD 3

CD 4

Conduit

Headworks

Chlorine

GWS

PowellButte

Portland Supply System Schematic/ Spreadsheet Connectivity Analysis

Supply System Reliability, 500-Year Return Earthquake

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

50 100 150 200 250 300 350

Flow (mgd)

Pro

bab

ilit

y o

f su

pp

lyin

g a

t

leas

t "x

" m

gd

No Intertie

Intertie

Portland Earthquake Reliability

Supply System Reliability, 100-Year Return Earthquake

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

50 100 150 200 250 300 350

Flow (mgd)

Pro

ba

bil

ity

of

su

pp

lyin

g a

t

least

"x

" m

gd

No Intertie

Intertie

Meets 100-year return reliability of 145 mgd

Requires mitigation to meet 500-year return reliability of 95 mgd

WRF, 2009

Seattle Water – Using EPANET

Restoration Calculations • Start with damage estimate of facilities and pipelines

• Identify which are required to restore service

• Estimate repair crews available – structures, equipment, large diameter pipe, distribution pipe – Internal, Contractors, Mutual aid

• Estimate repair rate/crew

• Develop repair sequence – Restore the most people the fastest

– Restore critical services – hospitals, industries etc.

• Calculate – Restoration days (by pressure zone)

– Restoration time line

– Person outage days (by pressure zone)

Water Restoration Timeline - Sendai

Distribution area restoration

Afte

rshock

occurred

★

Earthquake o

ccurred

★

Distribution area restoration

Distribu

tion are

a resto

ration

Began

receivin

g wate

r from

th

e S

ennan

Senen

Regio

nal A

rea to

Sendai

★

Tran

smissio

n pu

mp failu

re

Main trunkline restoration

Distribution station restoration Sennan

Senen R

egio

nal A

rea

wate

r distribu

tion se

cure

d by

rero

uting wate

r system

Received water from distribution station

The n

um

ber o

f the w

ater su

spension

×1,000 h

ouse

s

Person Outage Days

Improve Resiliency

• Upgrade or replace deficient facilities and pipe

• Enhance restoration procedures

• Emergency response

• Develop costs and implementation schedule

• Loop back to reevaluate performance levels

Where’s it Being Used ?

Variations of this scenario-based methodology are being widely used in the Pacific Northwest:

• Portland (Oregon Resilience Plan)

• Sammamish Plateau W&S

• Tacoma

• Tualatin Valley WD (Oregon Resilience Plan)

• Seattle – near future

Conclusions

• AWWA J-100 effective tool for assessing system resilience

• Risk Based

• Components

– Performance Goals

– Hazards

– Vulnerability/Fragility –Parameters

– System Analysis

– Societal Impacts and Business Interruption

– Improve Resilience

Tohoku Earthquake Japan 2011

Questions ? Donald Ballantyne, PE Ballantyne Consulting LLC dbballan@comcast.net

Kanigawa WTP, Tohoku Earthquake

Japan 2011