Recent Earthquakes: Implications for U.S. Water Utilities [Project
#4408]
ORDER NUMBER: 4408
DATE AVAILABLE: July 2012
PRINCIPAL INVESTIGATORS:
John Eidinger and Craig A. Davis
PROJECT PURPOSE:
The purpose of this project is to provide water agencies information that highlights the
following:
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Damage to water system infrastructure in three recent earthquakes (Chile 2010,
Christchurch 2010−2011, Japan 2011).
Response of the water agencies in repair and restoration of potable water service to
customers.
Effectiveness of various earthquake-countermeasures that were previously
implemented by these water agencies. This includes upgrades of tanks, buildings,
equipment, and (selectively) replacement of old buried pipe with "earthquake-proof"
pipe.
In order to understand:
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The factors causing water system service outages.
The strategies used and their effectiveness to restore water systems.
Water system restoration times.
The damaged infrastructure includes:
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Buried water pipes (PVC, Cast Iron, Asbestos Cement, welded steel, HDPE, etc.)
This includes both distribution pipes (commonly 6" to 12" diameter), transmission
pipes (commonly 24" to 96" or larger in diameter), and service laterals (commonly
under 2" diameter)
Water tanks. These include at-grade welded steel circular tanks, at-grade reinforced
concrete and prestressed concrete circular tanks, and below grade reinforced concrete
tanks.
Wells.
Water Treatment Plants/Pump Station Facilities.
The damage is addressed with regards to the various seismic hazards:
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Ground shaking
Ground failure due to liquefaction
©2012 Water Research Foundation. ALL RIGHTS RESERVED.
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Landslide
Surface faulting
Inundation (flooding) due to tsunami
Based on the observations from these recent earthquakes, this report provides guidance
for the effectiveness of possible U.S. water system improvements that are cost-effective
to address the following:
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Pipe replacement to address seismic weaknesses as well as pipe aging (leaks,
corrosion, etc.)
Water tank upgrades for seismic weaknesses
Well head seismic upgrades
Emergency Response preparedness and implementation (manpower, training,
equipment, mapping, communication with the public)
APPROACH:
To develop this report, the following approach was taken:
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The principal investigators for this project visited with the water utilities in the
affected countries: Mr. Eidinger visited Chile (April 2011), Christchurch (October
2010, April 2011, August 2011, December 2011), Japan (June 2010, October 2011,
February 2012). Dr. Davis visited Christchurch (April 2011), Japan (July 2011,
October 2011). Some of these visits were sponsored by the Water Research
Foundation, and others by the American Society of Civil Engineers (ASCE),
Technical Council on Lifeline Earthquake Engineering (TCLEE), and others
separately.
The researchers interviewed and collected information from the affected water
utilities, and visited many of the sites with damaged water infrastructure. Some of the
damage information presented in this report is based on tabulations developed by the
affected water utilities. The researchers followed up with some of the water utilities to
obtain additional maps, GIS information, reports, etc.
SUMMARY FINDINGS:
This report addresses the damage to water systems in three countries due to recent
earthquakes in 2010 and 2011. Table 1-1 highlights damage categories in each
earthquake.
©2012 Water Research Foundation. ALL RIGHTS RESERVED.
Table 1-1. Summary of Damage (N.A. = not applicable. Unk. = unknown)
Asset Category
Chile
2010
Damage to large diameter transmission pipes
Many
Damage to small diameter distribution pipes Thousands
and service laterals (CI, AC, PVC, etc.)
Damage to HDPE distribution pipe
None
Damage to Kubota chain-jointed ductile iron N.A.
pipe
Damage to at-grade wood, steel or pre-stressed Minor
concrete water storage tanks due to shaking
Damage to at-grade concrete water tanks due to None
ground failures
Damage to seismically-designed buried steel N.A.
tanks due to liquefaction
Damage to water treatment plants
Yes
Damage to pump stations
Unk.
Damage to wells
Not known
to have
occurred
Damage to elevated steel tanks
Fire ignitions due to earthquake
Fire ignitions due to tsunami
N.A.
~ 10
N.A.
Widespread
2
None
Christchurch
2010-2011
n.a.
Thousands
Japan 2011
Many
Thousands
None
N.A.
None
None
Many
Few
Yes
None
N.A.
Yes
N.A.
Yes
Widespread in
liquefaction
zones
Yes
Unk.
Suspected
due to salt
water
intrusion, but
not verified
N.A.
~ 124
~ 167
The key findings are as follows:
Chile Earthquake
This subduction zone earthquake seriously impacted the City of Concepcion, with a
population over 1,300,000 people. The water system in this city had not been designed
for earthquakes. Strong ground shaking and liquefaction damaged the city's only water
treatment plant. Liquefaction damaged many of the larger diameter steel transmission
pipelines. Liquefaction damaged many distribution water pipelines (about 3,000 total).
Water outages to customers were lengthy, over a month to some customers. Even so,
there was some good news: Essbio (the water system operator) had been installing HDPE
pipe in its water distribution system for about a decade prior to the earthquake; while the
rest of the water system suffered thousands of damaged pipes, no HDPE pipe was
damaged.
This earthquake also shook a wide area of Chile, much of it rural/farming. Over the prior
decade, the central government of Chile had installed 2,000 small wells – water tank
systems for these small farming communities (typical population of 100 people or fewer).
A standardized type elevated steel tank design was used throughout the country.
©2012 Water Research Foundation. ALL RIGHTS RESERVED.
Unfortunately, the design was insufficient for strong ground shaking, and at least 73 of
these elevated steel tanks collapsed, sometimes causing fatalities.
The restoration of water service after the earthquake was seriously slowed down by the
failure of the regional power supply and communication networks (cell phones). The
water companies had learned to use cell phones as their primary method for voice
communication. Primarily because of the failure of the widespread cell phone system,
restoration efforts were delayed by a few days.
There were two fire ignitions requiring fire department response after the earthquake;
there was no fire spread. The damage to the water system had no impact on the outcomes
of these fires.
Christchurch Earthquakes
A series of three crustal earthquakes hit Christchurch in September 2010, February 2011,
and June 2011. The earthquake affected an urban population of about 400,000 people.
Each earthquake damaged the water system. Between the three earthquakes, many
thousands of repairs to water pipe mains and sub-mains were required.
The water pipes and wells in this city had not been designed for earthquakes; a few of the
potable water tanks had been seismically upgraded prior to the earthquakes. Strong
ground shaking and liquefaction damaged many of the city's wells. Liquefaction damaged
many distribution water pipelines. Some of the water tanks performed well (some rooflevel damage still occurred), a few very small unanchored wood and steel tanks slid, and
several larger pre-stressed concrete tanks had serious damage (ongoing leaks) or failed
completely (lost all water contents). The city's largest concrete reservoir failed
completely due to ground deformations. Water outage durations to customers were
moderate, mostly restored within 10 days after each earthquake. Even so, there were
some good lessons learned: The Christchurch City Council (the water system operator)
had installed some HDPE pipe in its water distribution system after the first earthquake;
in the subsequent earthquakes, no HDPE pipe was damaged, while nearby older pipes
were damaged.
There were a few fire ignitions requiring fire department response after the first and
second earthquakes; there was no fire spread. The damage to the water system had no
impact on the outcomes of these fires.
Tohoku Earthquake
A magnitude 9 earthquake hit the northeastern part of Japan on March 11, 2011,
commonly called the Tohoku region of Japan. The earthquake affected an urban and rural
population of about 35,000,000 people. The largest city close to the epicentral area is
Sendai, with greater metropolitan population of about 1,500,000 people. The great
magnitude of the earthquake also resulted in some earthquake damage to water systems
in more distance large prefectures, including Chiba, Tokyo, Kanagawa, and others.
©2012 Water Research Foundation. ALL RIGHTS RESERVED.
The earthquake also triggered a major tsunami event. The tsunami event caused the vast
majority (likely over 95%) of all damage and fatalities in Japan, affecting just the first
few hundred meters (distances vary along the coastline) inland from the shore. Just
outside the tsunami inundation zone, damage to the regular building stock was nearly
zero. The tsunami seriously damaged many wastewater treatment plants located at the
low elevations near the coastline. The tsunami event had nearly zero impact on potable
water systems outside the inundation area.
In part due to the many large earthquakes in Japan's history over the past 100 years or so,
and in particular the 1923 Great Kanto earthquake (affecting Tokyo) and the 1995 Great
Hanshin earthquake (affecting Kobe), many (not all) of the larger water utilities in Japan
have undertaken extensive (and expensive) seismic countermeasures over the past 20
years or so. These countermeasures include seismic upgrade of tanks and water treatment
plant buildings/facilities; installation of underground emergency storage tanks; and most
importantly (and most expensively), wholesale replacement of older (more than 50+
years old) pipelines with new "seismic resistant" water pipes, mostly ductile iron with
chained joints (as manufactured by Kubota) and electro-fusion welded HDPE.
Two water treatment plants suffered major damage due to liquefaction.
A large diameter water transmission pipeline in the epicentral area suffered major
damage at more than 50 locations, mostly due to pulled slip joints. A few large diameter
water transmission pipelines suffered some slip joint damage in low-shaken areas, very
distant from the earthquake.
There was no known major damage to at-grade water tanks.
Below-grade emergency storage tanks, installed for purposes of providing potable
drinking water to local residents, in the event of damaged pipeline distribution networks,
mostly performed well (undamaged), but one performed poorly (liquefaction damage). It
seems that in areas where the emergency buried tanks performed well had no other major
damage, so they were mostly unneeded; in one area where the emergency buried tank
performed poorly, there was also a lot of damage to the buried pipeline network and
water outages were widespread and lengthy in duration.
At the time of the earthquake in March 2011, between 5% to 15% (some water utilities
have higher percentages of seismic-resistant pipe, others have none) of the water
pipelines in the strong-shaken area had been upgraded with seismic-resistant pipe. By
"seismic resistant pipe", it is meant pipe that can sustain a modest amount of ground
deformation without failure. In Japan, the most common types of ground failures are due
to liquefaction or landslide; given the nature of the earthquake hazard in Japan, fault
offset is not generally a concern (and there was none in the March 2011 earthquake).
None of the seismic-resistant pipelines is known to have been damaged in the March
2011 earthquake. The observed good performance of the seismic-resistant pipe cannot be
extended to say it would perform equally as well under highly concentrated ground
deformations due to fault offset.
©2012 Water Research Foundation. ALL RIGHTS RESERVED.
As of the time of writing this report (mid-2012), the tabulated count of fire ignitions is
315, of which 124 were caused due to the tsunami; 167 due to ground shaking; and 24
due to uncertain cause. In one coastal town impacted by the tsunami, some initial
ignitions spread and burned several neighborhoods. In all but one instance, the selfevacuation of people from the low lying area resulted in apparently no fire department
response to any of the tsunami-caused fires.
RECOMMENDATIONS FOR U.S. WATER UTILITIES:
Over the past 20 years or so, many U.S. water utilities in high seismic regions have
adopted seismic retrofit practices for buildings, water treatment plans, and tanks. The
lessons learned in these three earthquakes confirm that these practices remain sound
practice.
Even so, a major weakness remains for nearly all U.S. water agencies in high seismic
zones, namely that the existing buried pipe infrastructure remains highly susceptible to
damage due to earthquake-caused ground failures (liquefaction, landslide, surface
faulting, and other effects). Today, most U.S. water utilities continue to install nonseismically-designed distribution pipes, even in zones prone to ground failure effects. A
few U.S. utilities have seismically retrofitted (or replaced) the most critical large diameter
transmission pipes across known active earthquake faults, mostly using welded steel pipe,
and in a few cases, HDPE pipe.
These three recent earthquakes continue to show that the bulk of the total earthquake
damage to water systems, and the resulting water outages to customers, is due to failure
of hundreds to thousands of smaller diameter distribution pipes in zones of infirm ground.
Until water utilities install seismically-resistant pipes in these areas, this problem will
continue to re-occur in future earthquakes in the United States. New technology in water
pipeline joinery has been in place in Japan for nearly 20 years, and today (2012), it is
estimated that more than 75% of new water pipes installed in Japan use seismic-resistant
design; in California, less than 1% of new water pipes use seismic resistant design. For
common distribution pipes and service laterals (from under 1" to 8" diameter), HDPE
pipe (either fusion butt welded or electro-welded with clamped joints) appear to have
excellent earthquake performance, as evidenced in all three recent earthquakes. For
distribution and transmission pipes (from 3" to greater than 100" diameter), ductile iron
pipe with "chained" joints, as manufactured by Kubota of Japan, have had excellent
performance in the March 2011 and many other Japanese earthquakes.
Several areas for further applied research by the Water Research Foundation are
recommended:
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Develop a cost effective pipe replacement strategy for U.S. water utilities that factors
in the ongoing issues of aging pipeline replacements, as well as earthquakes. A
seismic design guideline for water pipes (ALA 2005) is currently available in the
United States, but it addresses only seismic issues. This guideline, coupled with
addition issues for pipe aging/corrosion, plus the ongoing lessons learned, should be
updated for practical implementation by U.S. water utilities.
©2012 Water Research Foundation. ALL RIGHTS RESERVED.
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Research into the failure of larger diameter water transmission pipelines at slip joint
locations. While ALA (2005) provides some guidance, the failed large diameter pipe
observations in Japan as well as other earthquakes shows that the current mandatory
design standards (such as AWWA M11 and others) are completely lacking in
requirements for seismically-designed slip joints (or bellows or similar). As part of
this research, a better understanding of the multiple failures of large diameter girthwelded steel pipes in liquefaction zones in Concepcion should be done to reveal the
root causes of these failures.
Review and update the Performance Goal targets that are suitable for U.S. water
utilities. As of 2012, different water utilities have adopted widely varying goals
(ranging from bulk water restoration in 1 day to as much as 30 days or longer after
major earthquakes), resulting in widely varying earthquake preparedness and
mitigation strategies, and capital costs. Nothing the researchers observed suggests that
Performance Goals should be legal mandates. Even so, if a water utility adopts overly
aggressive Performance Goals, the resulting cost impacts to ratepayers may seriously
outweigh the future benefits. With these considerations in mind, a review of the
various strategies recently adopted, addressing forecast benefits, and actual costs,
would be a useful document to utilities to help them select their own utility-specific
strategies.
Review and update the available fire following ignition models in ASCE (2005).
These models are also used by FEMA in HAZUS. In all three earthquakes, the
evidence appears to clearly indicate that the older models (ASCE, HAZUS) overpredict the number of earthquake-caused fire ignitions in modern cities (Concepcion,
Christchurch, Sendai, etc.). This may be in part due to the over-weight (ASCE,
HAZUS) of fire ignition data from the 1906 San Francisco earthquake, the 1933 Long
Beach earthquake, and other earthquakes where the widespread collapse of
unreinforced masonry buildings occurred; the use of modern electrical wiring; and
other factors. While fire ignitions are still occurring, they seem to be occurring at a
much lower rate (perhaps a 75% reduction) from that older earthquakes, like the 1906
San Francisco earthquake. If true, then the lower fire ignition rate would somewhat
lower (but certainly not eliminate) the need to seismically mitigate existing water
systems.
Review and update AWWA and other standards for steel and pre-stressed at-grade
concrete tanks to reflect ongoing poor performance of these tanks when exposed to
high levels of ground shaking. The unanchored steel tank provisions should be
carefully reviewed, especially for smaller steel tanks in high seismic hazard areas
(PGA 0.3g or higher). The combination of vertical earthquake and hydrostatic forces
for prestressed concrete tanks needs to be reviewed to ensure that yielding of hoopdirection prestress steel does not occur under high levels of ground shaking. The
acceptable ductility limits in current ASCE 7, IBC, ACI, and AWWA codes (ranging
from 2 to 4.5 or so) need to be reviewed and revised as suitable in order to provide
suitable reliability for a leak-tight tank under high levels of ground shaking.
©2012 Water Research Foundation. ALL RIGHTS RESERVED.
ADDITIONAL INFORMATION:
This report was written and edited between late 2011 to mid 2012. Over the next decade
or so, additional research into specific aspects of the water system performance will be
developed.
The interested reader should be aware that there are three organizations in the United
States that also have done reconnaissance into the effects of these three earthquakes:
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ASCE TCLEE sent out a number of investigation teams to Chile, New Zealand, and
Japan to document the performance of all types of lifelines, including water, power,
communications, gas and liquid fuels, ports and harbors, railroads, highways, debris
management, wastewater, etc. The authors of this report participated as part of those
teams. ASCE TCLEE plans to publish comprehensive reports on each earthquake,
including detailed discussions on the earthquake performance of water systems.
ASCE reports are available from www.ASCE.org.
GEER Association (Geotechnical Extreme Events Reconnaissance) teams have
developed reports on the seismic hazards portion of these earthquakes. GEER reports
on all three earthquakes are available from www.geerassociation.org.
EERI (Earthquake Engineering Research Institute) teams are developing reports on
performance of structures and societal response on all three earthquakes. A special
issue dedicated to the Chile 2010 earthquake, to be published in 2012, will include a
detailed discussion of the performance of the earthquake performance of the water
systems. EERI reports on all three earthquakes are available from www.eeri.org.
The interested reader should also be aware that some additional information from three
case studies of earthquake impacts to water systems is also available. These case studies
cover the experience in recent earthquakes in Chile, New Zealand (Christchurch), and
Japan (Tohuko earthquake), and are available to Water Research Foundation subscribers,
for information purposes only, upon request to the Water Research Foundation.
©2012 Water Research Foundation. ALL RIGHTS RESERVED.