The Lorna Prieta, California, Earthquake / of 

October 17, 1989-Lifelines 

ANSHEL J. SCHIFF, Editor 

PERFORMANCE OF THE BUILT ENVIRONMENT 

Thomas L. Holzer, Coordinator 

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1552-A 

Prepared in cooperation with the National Science Foundation 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1998 
DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary 

U.S. GEOLOGICAL SURVEY 

Charles Go Groat, Director 

Any use of trade, product, or firm names in this publication is 

for descriptive purposes only and does no$ imply endorsement 

by the U.S. Government 

Manuscript approved for publication, August 5, 1997 

Text edited by George A. Havach 

Library of Congress catalog-card No. 92-32287 

For sale by the 

U. S . Geological Survey 

Information Services 

Box 25286 

Federal Center 

Denver, CO 80225 
CONTENTS 

Pages 

Modeling the impact of the earthquake on telecommunication services------ 37 

By Michael L. Cohen 

Water and wastewater systems ...................................................... 47 

By LeVal Lund, John McLaughlin, Curt Edwards, Gordon Laverty, 

Holly Cornell, Alvin R. Guerrero, Michael Cassaro, Andries Godshack, 

George Brodt, Donald B. Ballantyne, Ronald Eguchi, Mary Pickett, 

Omar Abu-Yasein, Chenwun Lay, Anshel J. Schiff, James R. Blacklock, and 

Steven French 

Water- and wastewater-treatment plants ------ - - - --------- - - ------ - - 79 

By William Heuback and Donald B. Ballantyne 

Lessons learned by water and wastewater utilities-------------------------------- 87 

By Mark Pickett and Gordon L. Laverty 

Transportation systems ................................................................ 99 

By Joel Markowitz 

Transportation systems-seaports .................................................. Ill 

By Charles R. Farrar and A. Claude Griffin 

Transportation systems-passenger railways and buslines--------------------- 121 

By Stuart D. Werner and Anshel J. Schiff . . Residential natural-gas piping and appliances------------------------------------ 125 

By Peter W. McDonough 

Repair patterns for the gas-distribution system in San Francisco-------------- 129 

By Douglas G. Honegger 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

INTRODUCTION 

By Anshel J. Schiff, Precision Measurement Instruments and Stanford University 

CONTENTS 

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LOMA PRIETAA LIFELINES EARTHQUAKE 

To the general public who had their televisions tuned to 

watch the World Series, the 1989 Loma Prieta earthquake 

was a lifelines earthquake. It was the images seen around the 

world of the collapsed Cypress Street viaduct, with the frantic and heroic efforts to pull survivors from the structure that 

was billowing smoke; the collapsed section of the San Francisco-Oakland Bay Bridge and subsequent home video of a 

car plunging off the open span; and the spectacular fire in the 

Marina District of San Francisco fed by a broken gasline. To 

many of the residents of the San Francisco Bay region, the 

relation of lifelines to the earthquake was characterized by 

sitting in the dark because of power outage, the inability to 

make telephone calls because of network congestion, and the 

slow and snarled traffic. Had the public been aware of the 

actions of the engineers and tradespeople working for the utilities and other lifeline organizations on the emergency response 

and restoration of lifelines, the lifeline characteristics of this 

earthquake would have been even more significant. Unobserved by the public were the warlike devastation in several 

electrical-power substations, the 13 mi of gas-distribution lines 

that had to be replaced in several communities, and the more 

than 1,200 leaks and breaks in water mains and service connections that had to be excavated and repaired. 

Like the 1971 San Fernando, Calif., earthquake, which 

was a seminal event for activity to improve the earthquake 

performance of lifelines, the 1989 Loma Prieta earthquake 

demonstrated that the tasks of preparing lifelines in "earthquake country" were incomplete-indeed, new lessons had 

to be learned. 

LIFELINES AND THE ORGANIZATION OF 

THEIR INVESTIGATION 

The 14 papers in this chapter describe the earthquake 

performance of lifelines. Because one major consequence of 

the disruption of lifelines is its impact on emergency response, 

many of these papers also discuss the impact of lifeline disruption on the emergency-response communities. 

Three additional papers that are related to lifelines appear in other volumes of this series. The first paper (O'Rourke 

and others, 1992) describes the performance of lifelines in 

the Marina District; the second paper (Durkin and others, 

1994) describes the performance of the Public Safety Answering Point in Santa Cruz County, Calif.; and the third 

paper (Yashinsky, 1998) describes highway systems. 

The postearthquake investigation of lifelines presents 

several unique problems in comparison with the investigation of, say, a severely damaged building. First, lifelines are 

spatially distributed systems, and so it is extremely difficult 

for a single individual to cover an entire system. Second, each 

lifeline is typically a collection of various facilities, such as 

buildings or structures, links that interconnect the facilities, 

and equipment that may function as an integrated whole that 

is the lifeline. Indeed, some lifelines, such as seaports, are a 

collection of other lifelines and specialized facilities. The need 

for specialized knowledge about the construction, operation, 

interaction, and earthquake performance of structures, equipment, and system operations makes the investigation of lifelines such a challenge. Finally, in reporting on lifeline damage, 

it is important to do more that count the failures. To apply the 

lessons that can be learned from earthquake damage, the potential failure modes, the factors that may have contributed to 

the failures, and the impact of failures on the facility and the 

lifeline must all be identified. To address these issues, the 

Earthquake Investigation Committee of the Technical Council on Lifeline Earthquake Engineering (TCLEE) of the 

American Society of Civil Engineers (ASCE) has developed 

training materials and conducted training courses for lifeline 

investigators (Schiff, 199 1). 
A2 PERFORMANCE OF THE BUILT ENVIRONMENT 

After an earthquake, lifeline personnel have little time 

to discuss damage and its impact until service is returned to 

normal. Many lifeline facilities have controlled access, and 

for safety reasons, investigators are required to be accompanied by lifeline personnel, and so the investigation puts an 

added burden on personnel at the facility. Also, the large spatial distribution of lifelines means that it takes time for lifeline personnel to gather and assemble the information 

necessary to complete a picture of system damage and its 

impacts. Because of the importance of restoring lifeline functions, the cleanup of damage and the repair of the system 

starts immediately after the earthquake is over. For some lifelines, such as electrical-power and communication systems, 

much of the damage can be cleaned up within hours after the 

earthquake. For lifelines with buried distribution lines, such 

as water, gas, and sewage systems, a lengthy restoration process may be required in which damaged components must be 

identified, located, excavated, repaired, and tested. Thus, 

much of the damage may not be known by the utilities until 

days or weeks after an earthquake. For this reason, the investigation of lifelines requires an immediate response to 

observe damage before it is cleared, as well as later followup 

investigations once an overall picture of system damage and 

response can be pieced together. 

The investigation of these systems was coordinated by 

the Earthquake Investigation Committee of the TCLEE; the 

primary coordinators were Anshel J. Schiff and LeVal Lund. 

Members of the committee, primarily from outside of the San 

Francisco Bay region, members from the other technical committees of the TCLEE, and others worked on the investigation. Most of the papers in this chapter originally appeared in 

the preliminary report by Schiff (1990); many of these papers have now been revised to incorporate information gained 

since they were originally prepared, and additional papers 

have been added. In general, the first author listed coordinated the collection of data and edited and (or) wrote most of 

the paper; the other listed authors participated in the investigation and in preparation of the paper. 

Information gathered in the confusion of restoration immediately after an earthquake may be incomplete or inaccurate. Because lifeline investigations are typically conducted 

by professionals who volunteer their services, it is generally 

impossible to return to all sites to verify information. Although 

draft reports are sent to utilities for review and correction, 

discrepancies in the data may arise. 

ORGANIZATION OF PAPERS 

AND THEIR CONTENTS 

The TCLEE has adopted a format for papers describing 

observations made in a postearthquake investigations of lifelines. In general, the standard format starts with descriptions 

of the system, of the damage, and, where possible, of potential failure modes and factors that may have contributed to 

the failures. It continues with an identification of the impact 

of the damage and with comments on the emergency response 

and recovery, and concludes with observations and recommendations. 

NOTABLE OBSERVATIONS ON 

LIFELINE PERFORMANCE 

AND ITS CONSEQUENCES 

No attempt will be made here to summarize the findings of the 11 papers that deal with lifeline performance. 

Instead, I will highlight those features that stand out because 

of their uniqueness or importance. 

Significantly, many of the major lifelines in the San 

Francisco Bay region were rather distant from the earthquake 

epicenter, and the ground motions were generally of moderate magnitude and duration. However, the ground motions 

in many of these communities from future earthquakes on 

faults that run through or adjacent to them are expected to be 

much more severe. 

The poor performance of emergency power affected 

several lifelines and critical facilities, including powerplants, 

telephone-company central offices, airports, water systems, 

hospitals, and emergency-operation centers. A broad range 

of problems with emergency-power systems were observed. 

Failure modes and recommended practices for emergencypower generators are discussed by Schiff, Swan, and Mastuda 

(this chapter). 

ELECTRICAL-POWER SYSTEM 

The types of electrical-power-system damage observed 

in the 1989 Loma Prieta earthquake were similar to those 

observed in previous earthquakes. However, instead of the 

damage being concentrated at a single substation, in the 1989 

Loma Prieta earthquake five substations were damaged. As 

a result, the high level of redundancy designed into electrical-power networks and into substations was overwhelmed. 

In most previous earthquakes, the isolated damage at one or 

two substations could be circumvented, and electrical-powersystem performance was only slightly affected. The relatively 

good earthquake performance of the electrical-power system in the face of severe, widespread damage is largely attributable to the resourcefulness of utility personnel in working 

around damaged switchyard equipment. 

Damage to transformer bushings can cause extensive, 

long-term electrical-power disruptions. One factor contributing to the good earthquake performance of the electricalpower system was that damage to transformers was limited. 

Generally, if a switchyard is severely damaged, temporary 

powerlines can be routed around the switchyard directly to 

the transformers, as was done in this earthquake. If large 

power transformers are damaged, however, power disruption can be much more severe and longer in duration. In the 
INTRODUCTION A3 

earthquake, the damage to transformers was only limited. 

Three types of transformer damage were observed: Some 

high-voltage bushings developed oil leaks at the interface 

between the upper porcelain and the mounting flange, some 

transformer radiators developed leaks at the upper pipe flanges 

joining the radiators to the transformer body, and one transformer had an unexplained internal failure. Although costeffective methods for mitigating radiator leaks are available, 

protecting bushings is more problematic. 

The good performance of electrical-power systems in 

recent California earthquakes may not indicate the performance to be expected in other parts of the United States where 

older equipment is more prevalent and where earthquakes are 

expected to affect much larger geographic areas. Recent earthquakes have damaged vulnerable equipment in Western electrical-power systems. As the damaged equipment is typically 

replaced with more robust equipment and older vulnerable 

equipment is replaced with more rugged equipment in normal refurbishment, the earthquake ruggedness of Western electrical-power systems is improving. Because electrical-power 

systems in other parts of the United States have not sustained 

damaging earthquakes, they lack the seismic enhancement 

that is associated with new replacement equipment. In addition, the seismic upgrading regularly used by many Western 

utilities during normal refurbishment is not generally practiced in other parts of the United States. Thus, the earthquake 

performance of electrical-power systems elsewhere can be 

expected to be poorer than that observed in California. 

COMMUNICATION SYSTEM 

The good earthquake performance of modern communication equipment continues to validate the use of stringent 

seismic-qualification specifications that include requirements 

for vibration testing. However, the poor earthquake performance of communication-system emergency power and the 

severe damage to one tall building housing critical communication equipment indicate significant system vulnerabilities. 

Reliable emergency power is needed when commercial 

power is disrupted. Problems occurred with battery systems 

and engine generators, although the impact on system performance was minimal in the earthquake. A major communications company has embarked on a $ 10-million retrofit program 

to add external power hookups for emergency power to critical facilities. 

Damage to central-office structures in urban centers can 

cause widespread, long-term communication-system disruption. These structures need to be periodically evaluated and 

upgraded. The severe damage from the distant 1989 Loma 

Prieta earthquake to a large urban central-office building in 

Oakland that was designed to the then-applicable codes demonstrates communication-system vulnerabilities. Throughout 

the United States, older central-office structures are still in 

service. These structures were built to conform to older building codes, many of which had no seismic provisions; and they 

may have been designed by engineers with limited earthquake 

experience. Because new equipment commonly occupies only 

a small fraction of the volume of the older equipment it replaces and severe problems arise in relocating a central office 

because trunklines are already in place, strong economic incentives exist to continue using the old structures. Although 

retrofitting older buildings can be costly, because these building may contain equipment worth several billion dollars, a 

cost-benefit analysis may well justify the additional expense. 

WATER-DISTRIBUTION SYSTEM 

The risk of fire after an earthquake requires a careful 

review of the water-distribution system for fire suppression. 

Although the United States has been lucky in coping with 

fires after earthquakes, the 1989 Loma Prieta earthquake provided another warning that appears to have gone unanswered 

in most communities. For example, in the earthquake, both 

the regular and special fire-suppression water-distribution 

systems failed in the Marina District of San Francisco. The 

favorable wind conditions at the time of the earthquake and 

the use of a fireboat to provide bay water to fight the fire 

prevented its spread to adjacent wooden structures and averted 

a potential disaster. Because San Francisco is one of the few 

cities in the world with such a double fire-suppression waterdistribution system, this failure suggests that strategies for 

providing fire-suppression water, other than the normal waterdistribution system, should be considered, particularly in areas 

where soil liquefaction and ground failure can be expected. 

TRANSPORTATION SYSTEM-BRIDGES 

The damage to the San Francisco-Oakland Bay Bridge 

from this distant earthquake suggests that it and other large 

bridges elsewhere in the United States which were constructed 

before earthquake performance was given much consideration 

may be vulnerable to earthquake damage. The economic impact of severe damage and loss of operation of bridges that 

do not have nearby alternatives, whether they cross San Francisco Bay or the Mississippi River, will be significant to most 

communities. The damage to relatively new, freeway-type 

bridges located far from this earthquake also carries an ominous warning to other parts of the United States. 

TRANSPORTATION SYSTEM-SEAPORTS 

Earthquake damage to seaport facilities in the San Francisco Bay region was significant, particularly when the distance from the epicenter is taken into account. Many of these 

seaport facilities predate the introduction of modern earthquake-damage-mitigation measures in their design and construction; new seaport facilities in seismically active areas 
A4 PERFORMANCE OF THE BUILT ENVIRONMENT 

generally consider earthquake performance in their design. 

The retrofitting of existing seaport facilities is costly and disruptive to their ongoing operations. However, severe earthquake damage to seaport facilities will impact the local 

economy, both in the short term, while facilities are being 

reconstructed, and in the long term, because users establish 

new shipping patterns. Thus, upgrading seaport facilities can 

be a sound investment. 

NATURAL-GAS SYSTEM 

The widespread use of seismic gas-shutoff valves requires careful review and consideration of a different relight 

policy. After the earthquake, a week passed before gas service 

was reestablish for those customers in the Pacific Gas & Electric Co. service area who had shut off their gas. In Palo Alto, 

11 days were required to restore gas service, even though 

almost no earthquake damage in the community was reported. 

The types of shutoff valves that are currently available in the 

United States shut off the gas when triggered by earthquake 

vibrations, whether a gas leak has occurred or not. The use of 

such valves should require that users be responsible for relighting their own system, and procedures must be instituted 

so that users are instructed on how to do so properly. 

ACKNOWLEDGMENTS 

This chapter has required not only the voluntary efforts 

of the authors to seek out the information and prepare the 

papers, but also the willingness of the many lifeline personnel to meet with the investigators to make their data available, to describe system damage, and to explain its consequences. 

This cooperation was typically done at a time when the personnel were deeply involved in the recovery process. I gratefully acknowledge the willingness of utility personnel to share 

their knowledge and data with us. 

REFERENCES CITED 

Durkin, M.E., Thiel, C.C., Jr., and Schneider, J.E., 1994, Casualties 

and emergency medical response, in Tubbesing, S.K., ed., The 

Loma Prieta, California, earthquake of October 17, 1989-loss 

estimation and procedures: U.S. Geological Survey Professional 

Paper 1553-A, p. A9-A38. 

0' Rourke, T.D., Pease, J.W., and Stewart, H.E., 1992, Lifeline performance and ground deformation during the earthquake, in 

O'Rourke, T.D., ed., The Lorna Prieta, California, earthquake of 

October 17,1989-Marina District: U.S. Geological Survey Professional Paper 1551-F, p. F155-F179. 

Schiff, A.J., ed., 1991, Guide to post-earthquake investigation of lifelines: American Society of Civil Engineers, Technical Council 

on Lifeline Earthquake Engineering Monograph 3,261 p. 

Schiff, A.J., and Lund, LeVal, coordinators, Lifelines, chap. 8 of 

Benuska, Lee, ed., 1990, Lorna Prieta earthquake reconnaissance 

report: Earthquake Spectra, v. 6, supp. 90-01, p. 239-338. 

Yashinsky, Mark, 1998, The Lorna Prieta, California, earthquake of 

October 17, 1989-highway systems: U.S. Geological Survey 

Professional Paper 1552-B, 19 1 p. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

ELECTRICAL-POWER SYSTEMS 

By Anshel J. Schiff, Precision Measurement Instruments and Stanford University; 

San Swan, EQE International; 

and 

Edward N. Matsuda, Pacific Gas &Electric Co. 

CONTENTS 

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ABSTRACT 

The 1989 Loma Prieta earthquake significantly damaged electrical-power facilities and disrupted service in the 

earthquake-affected area. The Moss Landing, Hunters Point, 

and Potrero Powerplants went off line. The Moss Landing 

Powerplant, which was closest to the epicenter, was most 

heavily damaged. Damage there included minor buckling of 

the boiler support structure, and failure of a weld at the 

bottomside wall of a 750,000-gal raw-water-storage tank, 

which led to loss of the tank contents. In another tank located in the bottom of the one of the stacks, piping connections failed, and contents were lost. The steel liner in one of 

the stacks pulled away from the outer stack at about threefourths of its height; the unit could not provide power because the 500-kV switchyard to which it was connected was 

severely damaged. The powerplants in San Francisco, though 

only slightly damaged, shut down because of excessive load 

when power supplied from the peninsula was disrupted. 

Five substations were damaged, and three were severely 

damaged in parts of their 230- and 500-kV switchyards. All 

the live-tank circuit breakers at ground-shaking sites failed. 

Current transformers, disconnect switches, and lightning arresters also were significantly damaged. Transformer bushings and radiators were slightly damaged. To restore service, 

much of the damaged equipment had to be bypassed. 

Transmission lines were undamaged. Distribution lines 

in some areas came into contact with each other and blew 

fuses or burned through and dropped to the ground. 

INTRODUCTION 

The Pacific Gas and Electric Co. (PG&E) is the primary 

electrical-power utility in the earthquake-affected area (fig. 

1). A few communities, including the cities of Palo Alto, 

Alameda, and Santa Clara, have their own power-distribution systems, which contract for bulk electrical power delivered over the PG&E network. In addition, some of these 

communities have limited power-generating capacity. Many 

cogeneration plants are also located in the area, most of which 

are relatively small. 

Electrical-power systems can be divided into five major 

parts: (1) power-generating stations, (2) the power-transmission system, (3) the power-distribution system, (4) control 

and data-acquisition systems, and (5) ancillary facilities and 

functions. The function of each of these elements in the operation of the electrical-power system and the functions of 

the equipment used in the power transmission and distribution systems were described by Schiff (1973). 

Three PG&E power-generating stations are located 

within the earthquake-affected area. (1) The Moss Landing 
A6 PERFORMANCE OF THE BUILT ENVIRONMENT 

Powerplant, located by Monterey Bay, 8 mi south of Watsonville, 

has seven units, with a total capacity of about 2,000 MW. (2) 

The Potrero Powerplant, located by San Francisco Bay, has one 

210-MW unit and three 52-MW peaking units; peaking units 

are typically gas-turbine-powered generators that are used to 

meet demand during brief periods of very high load. (3) The 

Hunters Point Powerplant, also located by San Francisco Bay, 

has three units with a total capacity of about 390 MW and one 

52-MW peaking unit. Many other significant power-generating 

stations outside of the earthquake-affected area supply electrical power to the area through the transmission system. 

About 10 cogeneration plants are located in the earthquakeaffected area, ranging in size from 2.4 to 140 MW, with a total 

conjunction with industrial facilities that require large amounts 

of heat; combining the generation of heat and power can improve overall efficiency. 

The PG&E power-transmission system consists of a 

500-kV system that is part of the two a-c Pacific Interties 

that link the Northwest to southern California. A single 500- 

kV circuit branches off of the intertie and connects the Tesla 

Substation to the Los Baiios Substation through the Metcalf 

and Moss Landing Substations. A more extensive 230-kV 

transmission network provides power to the 60- and 1 15-kV 

subtransmission system that supplies the power-distribution 

system. A simplified schematic diagram of the power-transmission system in the earthquake-affected area is shown in 

capacity of about 400 MW. These plants are generally built in figure 1. 

/ 

Tesla 

\ 

Metcalf 

\ 

\ 

\ 

Figure 1 .-San Francisco Bay region, showing locations of electrical powerplants and substations. 
ELECTRICAL-POWER SYSTEMS A7 

The subtransmission system provides power at 60 and 

115 kV to distribution substations, which then provide power 

to feeders operating between 4 and 24 kV. One power grid in 

San Francisco operates at 12 kV; this grid is supplied power 

by the Potrero and Hunters Point Powerplants and from the 

San Mateo Substation through the Martin Substation (fig. 1). 

There are also 4- and 21-kV circuits in the city. 

To control the electrical-power system and provide protection, an extensive communication system exists that includes microwave links, carrier-frequency communication 

over the power-transmission lines, leased telephone lines, and 

commercial telephone lines. Communication is needed among 

the energy-control center, generating stations, and substations. 

An energy-control center coordinates power generation 

throughout the system through its dispatch function. Ancillary facilities include several service centers that stock some 

spare parts, provide parking for service vehicles, and dispatch 

service crews who maintain and repair the transmission and 

distribution systems. Storage depots have larger stores of supplies and store certain types of spare equipment. 

To characterize the seismic exposure of the facilities discussed below, we report on the epicentral distance of each 

facility and the peak ground acceleration recorded near the 

site. The fault rupture was about 24 mi long, and peak accelerations were sensitive to site conditions. 

EARTHQUAKE DAMAGE TO 

POWER-GENERATING STATIONS 

The three power-generating stations in the earthquakeaffected area are the Moss Landing, Hunters Point, and Potrero 

Powerplants (fig. 1). For completeness, we summarize below 

the damage sustained by each station, with emphasis on these 

stations as parts of a power-distribution system. The damage 

to industrial equipment in the stations was described by Stepp 

(1990). 

MOSS LANDING POWERPLANT 

The Moss Landing Powerplant is located by Monterey 

Bay, adjacent to Moss Landing, about 18 mi south of the earthquake epicenter (fig. 1). Damage associated with the Unit 6 

steam generator consisted of deformed or broken pipe restraints and pipe hangers, minor leaks in tubes within the 

boiler, damage to the windbox in the lower part of the boiler 

near a seismic restraint, a failed bearing on the low-pressure 

turbine, and damage to a seismic stop on the boiler-support 

structure. Other damage included the failure of an unanchored 

750,000-gal freshwater-storage tank and failure of pipe couplings on two 750,000-gal distilled-water tanks located in the 

base of the stacks, which caused a loss of the distilled water. 

The steel liner in one of the stacks pulled away from the stack 

at the three-fourths level; the stack was later reinforced with 

external, circumferential steel bands in this area. Substantial 

ground settlement occurred in the natural-gas-metering yard, 

and gas leaks occurred at pipe flanges at a secondary gasmetering station associated with the boiler's gas supply. 

The initial estimate of the damage to the Moss Landing 

Powerplant, not including damage to the switchyard, was $4.5 

million. 

HUNTERS POINT POWERPLANT 

The Hunters Point Powerplant is located on the southeast edge of San Francisco, about 27 mi from the earthquake 

epicenter (fig. 1). At the time of the earthquake, Units 1 and 2 

were operating, and Unit 3 was down for maintenance. Some 

cracks occurred in the top of the boiler enclosure on Unit 3, 

and a shear wall was cracked. Minor cracks and spalling of 

concrete occurred in several places, and a minor leak occurred 

in a pipe coupling to a water tank. 

POTRERO POWERPLANT 

The Potrero Powerplant is about 1 mi north of the Hunters Point Powerplant, about 28 miles from the earthquake 

epicenter. Bracing in the waterbox was damaged, and the 

boiler's seismic stops were slightly damaged. 

OTHER POWER-GENERATING STATIONS 

Most cogenerating plants in the San Francisco Bay region were undamaged. Two plants were damaged and came 

back on line 2 days and 12 hours, respectively, after the earthquake. Although many of the 10 cogenerating plants in the 

earthquake-affected area were located in the region of strong 

shaking, they were undamaged. How much of the 400-MW 

capacity of these plants was supplied to the power grid is 

unknown. Power contributed by cogenerating plants in the 

Watsonville area played an important part in meeting local 

demand due to disruption to transmission facilities. 

EARTHQUAKE DAMAGE TO THE 

POWER-TRANSMISSION SYSTEM 

The damage to transmission substations significantly 

affected the electrical-power system. The Metcalf, Moss 

Landing, and San Mateo Substations were heavily damaged, 

whereas the Monte Vista and Newark Substations were less 

damaged (fig. 1). Live-tank circuit breakers were severely 

damaged, and transformer radiators developed oil leaks and 

had damaged bushings. Current transformers failed or developed oil leaks, air disconnect switches were damaged, and 

transfer buses were damaged. Other reported damage had 

little effect on system operations. 
A8 PERFORMANCE OF THE BUILT ENVIRONMENT 

In the subsections below, we describe each damaged 

transmission substation, indicate its seismic exposure, and 

identify damaged and undamaged equipment. We use the following terminology to describe power connections within 

substations. The power conductors that connect substation 

equipment are called buses, of which two types are used: a 

rigid bus, which is typically made of aluminum pipe; and a 

flexible bus, which is made of twisted aluminum cable. 

MOSS LANDING SUBSTATION 

The Moss Landing Substation is north of and adjacent 

to the power-generating station, which is about 18 mi southeast of the earthquake epicenter (fig. 1). The nearest strongmotion-recording instrument, which is located in Watsonville, 

about 8 mi north of Moss Landing, recorded a peak horizontal ground acceleration of 0.39 g; the duration of strong shaking was about 10 s. Within the substation, no evidence of 

liquefaction, lateral spreading, or differential settlement was 

observed. 

The Moss Landing Substation has 1 15-,230-, and 500- 

kV switchyards; the 115-kV switchyard was damaged. 

The general layout of the 500-kV switchyard is shown 

in figure 2A, where a single line is used to describe the three 

phases of a circuit, each phase consisting of one conductor. 

Likewise, such pieces of equipment as circuit breakers and 

transformers are grouped together in threes, with one unit for 

each phase. The switchyard is configured in a ring, with four 

Westinghouse SF-insulated live-tank circuit breakers and one 

High Voltage Breakers, Inc. (HVB), SF-insulated dead-tank 

circuit breaker. Not shown in figure 2A is the current transformer associated with each phase of the live-tank breakers 

and the capacitatively coupled voltage transformers (CCVT's) 

associated with each phase of the dead-tank circuit breaker. 

One circuit is connected to the Metcalf Substation, and one 

to the Los Bafios Substation; one circuit is connected to a 

bank of 5001230-kV transformers; and two circuits are connected to Moss Landing Powerplant Units 6 and 7. The general layout of the 500-kV switchyard is shown in figure 2A, 

and the general layout of the 230-kV switchyard in figure 2B. 

The switchyard has a segmented-double-bus configuration. 

All circuit breakers are of the oil type. 

SUMMARY OF DAMAGE 

Within the 500-kV switchyard at the Moss Landing Substation, the four live-tank circuit breakers were all severely 

damaged. Of the 12 current transformers, 10 were severely 

damaged; and only 17 of the 42 disconnect switches were 

undamaged. The porcelain supports for one phase of bus 1 

failed, causing the rigid bus to fall to the ground. One of the 

porcelain supports on one phase of bus 2 failed, allowing the 

bus to sag, but it remained functional. The porcelain members of four CCVT's and two line traps failed. The three phases 

of the dead-tank circuit breaker, the six nearby disconnect 

switches, the three CCVT's, and the rigid bus used with the 

dead-tank circuit breaker were all undamaged, as were the 

supports for the flexible bus. The six single-phase transformers and the three single-phase 5001230-kV transformers were 

also undamaged. 

Within the 230-kV switchyard, most of the damage was 

to disconnect switches supported on the 230-kV bus-support 

structures. The rest of the equipment in the switchyard, including the bulk-oil circuit breakers, was undamaged. A detailed schematic diagram of the 500-kV switchyard is shown 

in figure 3. 

Here, we describe each type of equipment, along with 

the types of damage it sustained, followed by an overall evaluation of possible interactions. We note that equipment of a 

given type-for example, disconnect switches-may have 

been made in different years or by different manufacturers. 

LIVE-TANK CIRCUIT BREAKERS 

Four Westinghouse SF-insulated, seismically strengthened, live-tank circuit breakers were installed in the 500-kV 

switchyard at the Moss Landing Substation (fig. 1). A similar 

circuit breaker at the Metcalf Substation is shown in figure 4. 

The seismically strengthened version of this circuit breaker 

has posttensioned fiberglass tendons within the interrupterhead-support columns to hold the interrupter head and the 

column members together. The column consists of four porcelain cylinders, stacked on top of each other and separated 

by rubberlike gaskets. The non-seismically strengthened circuit breakers have wooden rather than fiberglass tendons. The 

non-seismically strengthened units have three external diagonal ceramic members connecting the interrupter head to the 

support structure that were provided to resist wind loads. The 

three columns are supported on a six-legged steel frame; each 

leg is anchored by a friction clip held by a 1-in.-diameter 

cast-in-place bolt, as shown in figure 5. Each circuit-breaker 

phase is connected to a disconnect switch with rigid bus and 

to a current transformer. 

Two types of circuit-breakerlcurrent-transformer connections were used: flexible-conductor-loop type (fig. 4) and 

rigid-connection type (fig. 6). The circuit breaker shown in 

figure 5 is a very flexible loop; the other type is a rigid-bus 

connection. Item 16 in figure 3 has rigid connections, and all 

the other live-tank circuit breakers have flexible connections. 

All of the 12 phases of the live-tank circuit breakers in 

the 500-kV switchyard were damaged, 2 phases of item 16 

(fig. 3) were removed, and the details of their damage is unknown. All the friction-clip anchors had bent or stretched bolts, 

allowing the circuit breakers to move. Three types of circuitbreaker failures were noted. In the first type of failure (fig. 

6), one phase slid off its support pad, and the entire circuit 

breaker, including its support structure, tipped over (for example, item 13, fig. 3). In the second type of failure (fig. 7), 
ELECTRICAL-POWER SYSTEMS 

North 4 Moss Landing - 

Metcalf 

19 Flexible Bus 

Â¥ 

McGraw Edison 

kV Transformers 

I I 

Flexible BUS - 

I 

Flexible Bus 

Bus 1 

(Rigid Bus) 

Flexible Bus ^ I Moss Landing - 

Bus 2 v (Rigid Bus) 

\. 

Â¥ I 

Flexible Bus All bus is rigid bus except as noted 

^ unit 7 Moss Landing 

- Unit 6 Power Plant 

Circuit Breaker 

1 Disconnect Switrch 

Metcalf Metcalf 

4 4 

115 kV Bus 

Panoche 

& 

500 kV 

Switchyard 

Section F 

Generation Generation Generation Generation Generation 

B 

Figure 2.-One-line diagrams of 500-kV (A) and 230-kV (B) switchyards at the Moss Landing 

Substation (fig. 1). A single line is used to designate the three phases of each circuit, each phase 

consisting of one conductor. Likewise, such pieces of equipment as circuit breakers and transformers are grouped together in threes, with one unit for each phase. 
A10 PERFORMANCE OF THE BUILT ENVIRONMENT 

the interrupter-head-support column collapsed, and the interrupter fell to the ground (for example, item 4, fig. 3). In 

the third type of failure (fig. 8) the support column shattered, 

but the interrupter head did not fall over (for example, item 

10, fig. 3). In other circuit breakers, the support column was 

cracked but did not shatter. Support columns of this design 

contain SF, gas for insulation, and so a crack in the porcelain will generally put the circuit breaker out of service. 

Live-tank circuit breakers of this general design-that 

is, with a heavy interrupter head supported on top of a tall 

ceramic column-have been damaged in previous earthquakes. The seismically strengthened versions described here 

performed better than the unstrengthened version. For example, several unstrengthened 500-kV circuit breakers were 

damaged at the Los Bafios Substation in the 1984 Morgan 

Hill, Calif., earthquake when subjected to a peak acceleration of only about 0.05 g. 

CURRENT TRANSFORMERS 

A current transformer is associated with each of the 12 

phases of live-tank circuit breakers. Two damaged current 

transformers associated with live-tank circuit breakers are 

shown in figure 9 and as item 4 in figure 3. The support stmcture has four legs, each secured with a friction clip similar to 

that shown in figure 5. The current-transformer tank is supported on a "chair" made of channel-shaped structural members, as shown in figure 10. The current transformers are 

connected to the disconnect switches with a rigid bus and to 

the circuit breakers as described above; the current transformers shown in figures 8 and 9 are connected with a flexible bus in a looped configuration. 

The anchorage of the current transformers did not fail, 

except for one phase on item 13 in figure 3. Only 2 of the 12 

current transformers at the Moss Landing Substation were 

North (Rel.) 

I I mmmmmma~mmmmnmmmmammmam.m 

I I Items 18 and 19 are not shown. 

Live-Tank 

Circuit Breaker 

To LOS Banos 

Line Trap 

and CCVD 

Current 

Transformer 

Dead-~ank w Circuit Breaker 

A Bus S~ippoit 

. . . . Flexible BUS 

- Rigid Bus 

Figure 3.-Schematic diagram of 500-kV switchyard at the Moss Landing Substation (fig. I), showing locations of damaged and removed 

equipment and numbered items referred to in text. Equipment shown as undamaged may have required repair that was not obvious from 

cursory inspection. A, 500-kV circuit breaker (fig. 6); B, interrupter heads on 500-kV live-tank circuit breaker (fig. 7); C, interrupter-headsupport columns on 500-kV circuit breaker (fig. 8); D, 500-kV current transformer (fig. 9); E, support of 500-kV current transformer (fig. 

10); F, disconnect switch with rigid bus (fig. 11); G, disconnect switch with flexible bus (fig. 12); H, disconnect switch of channel design 

(fig. 13). CCVT, capacitatively coupled voltage transformer. 
I 

ELECTRICAL-POWER SYSTEMS A1 1 

undamaged. Most current-transformer failures were caused 

by cracking of the porcelain member in its upper half, as 

shown in figure 9. Several current transformers folded over 

at the porcelain break, located at about the three-fourths level. 

The two current transformers that did not fail had flexible 

connections to the circuit breakers. In most of the circuit 

breakers that fell over, the connection between the circuit 

breaker and the current transformer failed after the current 

transformer had been severely damaged. A simple analysis 

of similar current transformers and support structures that 

was performed after the 1984 Morgan Hill, Calif., earthquake 

(Schiff, 1985) indicated that the support structure was relatively flexible and that the current transformer had a natural 

frequency of about 2 Hz. 

Figure 6.-Overturned 500-kV circuit breaker at the Moss Landing 

Substation (fig. 1). 

Figure 4.-SF-insulated, seismically strengthened live-tank circuit 

breaker at the Metcalf Substation (fig. 1). 

Figure 7.-Fallen interrupter heads on 500-kV live-tank circuit 

breaker at the Moss Landing Substation (fig. 1). 

Figure 5.-Friction-clip anchorage of 500-kV circuit breaker at the 

Moss Landing Substation (fig. 1). 

Figure 8.-Shattered interrupter-head-support columns on 500-kV 

circuit breaker at the Moss Landing Substation (fig. 1). 
PERFORMANCE OF THE BUILT ENVIRONMENT 

Figure 9.-Damaged 500-kV current transformer 

at the Moss Landing Substation (fig. 1). 

cast-in-place bolt through a plate at the bottom of each of 

four legs. Items 1, 2, 18, and 19 in figure 3 were connected 

with long drops of flexible bus from overhead flexible bus 

runs, as shown in figure 12. Three disconnect switches of the 

channel type are shown in figure 13 (item 3, fig. 3). Of the 12 

phases of the tube-type construction, 3 failed; none of these 

failures is attributable to the failure of adjacent equipment. 

Of the 24 channel-type disconnect switches, 22 were damaged, but most were adjacent to equipment that had failed 

and collapsed. 

Of the 42 single-phase switches, 25 failed. Four types of 

failures were noted: (1) in 12 disconnect-switch phases, the 

outside column that supports the knifeblade failed; (2) in nine 

disconnect-switch phases, both of the knifeblade-support columns failed; (3) in four disconnect-switch phases, only the 

knifeblade-receiver column failed; and (4) in five disconnectswitch phases, both the knifeblade-support and knifebladereceiver columns failed. We note that although many of these 

failures occurred at the bottom of the column, the point of 

largest cantilever load, many columns failed at other points, 

suggesting higher modal response. None of the six phases of 

the disconnect switches of the tubular design associated with 

dead-tank circuit breakers failed. In figure 11, one of these 

blades is not aligned with the other two phases, suggesting 

that it may have been damaged. The two disconnect switches 

shown in figure 12 (item 1, fig. 3) were also of the tubular 

design. The knifeblade-receiver columns on the switches failed 

and are shown hanging from the flexible bus. A similar failure occurred on one phase of a disconnect switch (item 19, 

not shown in fig. 3). Each of the three phases of the disconnect switch shown in figure 13 illustrates a different type of 

failure: The unit on the left has lost one of the porcelain columns supporting the knifeblade, the unit in the center has 

also lost the knifeblade-receiver column, and the unit on the 

right has just lost the knifeblade-receiver column. Of the 12 

disconnect-switch phases that use flexible conductor connections, 3 failed; and of the 30 disconnect-switch phases that 

use rigid conductor connections, 22 failed. 

Figure 10.-Detail of damaged 500-kV current transformer (fig. 9) 

at the Moss Landing Substation (fig. 1). LINE TRAPS AND CAPACITATIVELY COUPLED 

VOLTAGE TRANSFORMERS 

DISCONNECT SWITCHES 

The disconnect switches are supported on two lattice 

columns. The switches are of the vertical knifeblade type, in 

which the knifeblade is supported by two porcelain columns. 

The knifeblade receiver is supported by a single porcelain 

column. A disconnect switch is shown on the right side of 

figure 11, with the knifeblade up. We observed two designs: 

in one design, the base of the disconnect switch is made of 

channels; and in the other design, the base is made of a tubular member. Items 1,2,6, and 8 in figure 3 were of the tubular design; the lattice structures were anchored with a 

Each phase of the two circuits that leave the site has a line 

trap and CCVT mounted on a single truss-type structure, as 

shown in figure 14. Each of the four legs is anchored by a castin-place bolt through a plate at the end of each leg. A long flexible bus dropping from an overhead flexible bus forms the bus 

connections. 

The line trap and CCVT failed on one assembly, although 

it is uncertain which component failed first; the CCVT failed at 

the base of the porcelain column on three assemblies; and a line 

trap failed on another assembly. Three failure modes are possible: (1) from inertial loads, possibly compounded by dynamic 

effects of the devices and their support structures; (2) from the 
ELECTRICAL-POWER SYSTEMS A13 

dynamic effects of long, flexible cable drops; and (3) from lateral motion of the overhead buses that could apply loads to the 

connections. Although all of these factors contributed in varying degrees to the failures, it is unclear whether any dominated. 

BUS SUPPORTS-RIGID BUS 

Two long transfer buses are located along the east and 

west ends of the 500-kV switchyard at the Moss Landing Substation. The bus is supported on lattice structures topped with 

a post insulator, as shown on the lower left side of figure 12. 

Additional isolated bus-support failures occurred between 

pairs of disconnect switches (items 5 and 6, 11 and 12, 14 

and 15, fig. 3). 

Two of the three phases of bus 1 are shown in figure 12. 

The support column without the post insulator is associated 

with the failed bus phase. Failure of a single bus support on 

bus 2 allowed the bus to sag, but the bus remained operational. 

Figure 11 .-Disconnect switch with rigid bus at the Moss Landing 

Substation (fig. 1). 

Figure 13.-Disconnect switch of channel design at the Moss Landing Substation (fig. 1). 

Figure 12.-Disconnect switch with flexible bus at the 

Moss Landing Substation (fig. 1). 

Figure 14.-Line trap and capacitatively coupled voltage transformer on support structure at the Moss Landing Substation (fig. 1). 
PERFORMANCE OF THE BUILT ENVIRONMENT 

DEAD-TANK CIRCUIT BREAKERS METCALF SUBSTATION 

Part of the HVB SF-insulated, dead-tank circuit breaker 

is visible at the right in figure 11. Each of its four legs is 

welded to a steel embedment, as shown in figure 15. The circuit breaker is connected by rigid bus to a disconnect switch 

on one side and to a CCVT on the other; the CCVT is also 

visible in figure 11. The circuit breakers and all the equipment associated with them were undamaged, with the possible exceptions noted above. 

BUS SUPPORTS-FLEXIBLE BUS 

The tall, flexible-bus-support structures were undamaged. They are of lattice-type construction and anchored with 

cast-in-place bolts, as shown in figure 12. 

SUMMARY OF SWITCHYARD DAMAGE 

The 230-kV switchyard at the Moss Landing Substation 

with bus sections D, E, and F is shown in figure 2B. On bus 1, 

disconnect switches mounted on the buswork of sections D, 

E, and F were severely damaged. On bus 2, the disconnect 

switches were severely damaged on section F, moderately 

damaged on section E, and undamaged on section D. The 

115-kV switchyard was undamaged. 

Any assessment of the interaction of failures must be speculative here because no observers or automatic, seismically triggered video systems were on hand to provide direct accounts or 

documentation of the sequences in which damage occurred. A 

review of the pattern of failures indicated in figure 3 suggests 

that equipment interaction played a role in many, though apparently not all, failures. Observations of the equipment 

that fell over and that which remained standing suggest that 

the failure of the live-tank circuit breakers contributed to the 

damage of other equipment. Components were damaged on 

six disconnect-switch phases that were not directly attached 

to circuit breakers. 

Figure 15.-Detail of welded anchorage on 500-kV dead-tank circuit breaker at the Moss Landing Substation (fig. 1). 

The Metcalf Substation is located adjacent to and just 

west of California Highway 101 and south of Metcalf Road, 

about 16 mi northeast of the earthquake epicenter (fig. 1). 

Records obtained about 7 mi southeast and 7 mi west of the 

substation showed peak ground accelerations of 0.28 and 0.19 

g, respectively. 

The Metcalf Substation has 115, 230-, and 500-kV 

switchyards. The general layout of the 500-kV switchyard is 

shown in figure 16. The switchyard is configured as a ring 

bus, with three Westinghouse SF-insulated, seismically 

strengthened live-tank circuit breakers and one HVB SF-insulated dead-tank circuit breaker. There are single-circuit 

transmission lines connecting it to the Tesla Substation to the 

north and the Moss Landing Substation to the south (fig. 1). 

A transmission line goes to each of two 5001230-kV transformer banks. The 230-kV switchyard has a segmented double 

bus, with two transmission circuits to the Newark and Moss 

Landing Substations and three transmission circuits to the 

Monte Vista Substation (fig. 1). It supplies two 23011 15-kV 

transformer banks. The 1 15-kV switchyard was undamaged. 

SUMMARY OF DAMAGE 

Within the 500-kV switchyard, all three live-tank circuit breakers were damaged. Five of the nine current transformers associated with the circuit breakers had oil leaks. One 

phase of a disconnect-switch phase appeared to have been 

pulled down when the circuit breaker to which it was connected failed. In the two banks of single-phase, 5001230-kV 

transformers, bank 2 consisted of four single-phase transforrners. The spare transformer replaced a transformer with a damage 500-kV bushing flange that was deformed and leaking. 

Minor radiator leaks occurred. Bank 1 consisted of three 

single-phase transformers that had severe leaks at flanges 

which support transformer radiators. In one phase, a 230-kV 

lightning arrester attached to bank 1 failed and fell to the 

ground. 

In addition, four line traps, five CCVT7s, and 23 air disconnect switches were undamaged. An HVB dead-tank circuit breaker was also undamaged and showed no signs of 

distress. Bus-support structures and rigid buses were undamaged. A schematic diagram of the 500-kV switchyard is shown 

in figure 17. This diagram shows all major equipment items 

for each phase and corresponds to the layout in figure 16. 

The discussion of the damage to the live-tank circuit breakers at the Moss Landing Substation also applies here. In general, the damage at the Metcalf Substation was less severe. 

Although friction-clip anchors also failed, the equipment 

moved only from 2 to 8 in. A smaller fraction of interrupterhead-support columns failed than at the Moss Landing Substation. One disconnect-switch phase failed when it was pulled 

down by a damaged circuit breaker to which it was connected. 
ELECTRICAL-POWER SYSTEMS 

I 

13 12 11 * Flexible Bus Flexible Bus Tesia- - Metcalf 

Rigid Bus It 1 -Flexible Bus 

-Flexible Bus 7 -Flexible Bus 

Bank #1 

5001230 kV 5001230 kV 

1 All bus is rigid except as noted I T to 230 kV bus 

* to 230 kV bus 

Figure 16.-One-line diagram of 500- 

kV switchyard at the Metcalf Substation 

(fig. 1). All buses are rigid except as labeled. 

Figure 17.-Schematic diagram of 500-kV switchyard at the Metcalf Substation (fig. I), showing locations of damaged and 

removed equipment and numbered items referred to in text. Equipment shown as undamaged may have required repair that was 

not obvious from cursory inspection. Same symbols as in figure 3. 
A16 PERFORMANCE OF THE BUILT ENVIRONMENT 

Fewer interrupter heads fell than at the Moss Landing Substation. Individual interrupter-head-support columns (columns 

adjacent to current transformers, the center column, and columns adjacent to disconnect switches) were damaged on some 

phases. None of the current transformers failed, although five 

developed oil leaks. The rigid-bus connections between the 

current transformers and the circuit breakers in place at the 

time of the 1984 Morgan Hill, Calif., earthquake had all been 

replaced with the flexible loops shown in figure 8. The bussupport structures and buses were undamaged. Four line traps, 

five CCVT's, and 23 air disconnect switches were undamaged. 

The HVB dead-tank circuit breaker was undamaged and 

showed no signs of distress. It had been installed on a pad 

remaining from a live-tank circuit breaker that was damaged 

in the 1987 Morgan Hill, Calif., earthquake. The three bolts 

used on each of the four legs are shown in figure 18; the equipment is nearly identical to that shown in figure 12. 

The 230-kV switchyard was undamaged, but some disconnect switches became misaligned, so that they would not 

reclose once they were opened. The switchyard's two General Electric model ATB6 live-tank circuit breakers were undamaged (fig. 19). In past earthquakes, these circuit breakers 

were vulnerable to earthquake damage. All other circuit breakers of the oil type or dead-tank type were undamaged. 

Figure 18.-Detail of bolted anchorage on 500-kV dead-tank circuit breaker at the Metcalf Substation (fig. 1). 

Figure 19.-Undamaged General Electric model ATB6 live-tank circuit breaker in 230-kV switchyard at the Metcalf Substation (fig. 1). 

SAN MATE0 SUBSTATION 

The San Mateo Substation is located just north of the 

San Mateo Bridge, adjacent to San Francisco Bay and about 

42 mi from the earthquake epicenter (fig. 1). The nearest 

strong-motion-recording station, about 2 mi away in Foster 

City, recorded a peak horizontal ground acceleration of 0.16 

g. The substation appears to be located on fill, but no evidence of liquefaction or lateral spreading was observed. However, circuit-breaker foundation pads, which were supported 

on piles, indicated that the ground surrounding the pads had 

settled 4 to 6 in. On the east boundary of the site, away from 

any equipment, some slumping occurred, and the ground was 

quite soft. 

The San Mateo Substation has 60-, 115-, and 230-kV 

switchyards. The 230-kV switchyard has a segmented double 

bus, as shown in figure 20. One circuit goes to the Martin 

Substation through an underground cable, four go to transformers that feed the 115-kV bus, two go to the Newark Substation, and two go to power-generating stations. 

Within the 230-kV switchyard at the San Mateo Substation, one General Electric model ATB4 and three General 

Electric model ATB7 live-tank circuit breakers were damaged. These circuit breakers have two interrupter heads, which 

are supported on porcelain columns formed of post insulators that are bolted together, as shown in figure 21. (The 500- 

kV circuit breakers had three interrupter heads, which were 

held together by internal tendons.) The support structure (fig. 

22) is a lattice structure anchored by eight cast-in-place bolts; 

the tank shown in the figure is the bottom part of a current 

transformer, which is incorporated into one of the unit's support columns. The circuit breakers exhibited three failure 

modes: failure of one of the porcelain support columns, commonly the column that contains the current transformer; failure of the ceramic members that make up the high-pressure-air 

plumbing; and blowing of the interrupter-head gaskets on the 

bushings that connect the two interrupter heads. A blown interrupter-head gasket is shown in figure 23. Similar equipment at the Edmonston Pumping Plant failed in the 1988 Tejon 

Ranch, Calif., earthquake; the failure modes were discussed 

in detail by Schiff (1989). Although the circuit-breaker-support structures at the San Mateo Substation were not as massive or stiff as their counterparts at the Edmonston Pumping 

Plant, this difference probably did not affect the response 

because the natural frequencies of the interrupter heads on 

their support columns are relatively low. 

On the 230-kV bus-support structure, several bus connections to disconnect switches were damaged. Two disconnect switches mounted on a bus-support structure failed. In 

two places, cables disconnected at hook-and-slot attachments 

to the buswork. Two CCVT's failed. Oil-type circuit breakers 

were undamaged. 

A review of the disassembled circuit breakers in the 

"graveyard at the San Mateo Substation indicated that the 

initial response of each circuit breaker caused the interrupter- 
ELECTRICAL-POWER SYSTEMS 

Transformer 

Circuit Breaker 

Disconnect Switch 

a 

Most bus is flexible 

Figure 20.-One-line diagram of 230-kV switchyard at the San Mateo Substation (fig. 1). Most buses 

are flexible. 

Figure 21.-Interrupter-head-support columns on 230-kV circuit 

breaker at the San Mateo Substation (fig. 1). 

Figure 22.-Support structure of 230-kV live-tank circuit breaker 

at the San Mateo Substation (fig. 1). 

head gaskets to fail in one of two ways. (1) Inplane, inphase 

rocking of the two interrupter heads on their columns caused 

the interrupter-head gaskets to blow on the top and bottom of 

three sets of circuit breakers, as shown in figure 24; the gasket on one head was blown at the top, and on the adjacent 

head the gasket was blown on the bottom. (2) Out-of-plane, 

out-of-phase rocking on one set of interrupter heads caused 

the gaskets to blow on the side of the bushings. Data from the 

Edmonston Pumping Plant indicate that this type of failure 

occurs before the support columns shatter. The absence of 

surviving porcelain members associated with the high-pressure-air supply and current-transformer- and interrupter-headsupport columns suggests that these members shattered and 

were discarded with other porcelain shards. 

The San Mateo Substation has three banks of 23011 15- 

kV transformers. One bank of transformers developed oil leaks 

Figure 23.-Blown interrupter-head gasket on 230-kV circuit breaker 

at the San Mateo Substation (fig. 1). 
PERFORMANCE OF THE BUILT ENVIRONMENT 

Interrupter Head 

Muffler 

Support 

Column 

Interrupter Head 

bushing gasket , Interrupter Head (2) 

Air supply 

'and contrc 

rod 

A \ 

nterrupter Head 

rushing gasket (8) 

Interrupter head 

, 

bushing (4) 

Bus connection 

Current Transformer 

and support column 

Porcelain Member 

1 - Damaaa Kev a- -, 

A Broken Current Transformer Support 

Column 

B Broken Air Supply Porcelain Column 

u u 1 11 C Blown Interrupter Head Gasket 

Figure 24.-Schematic diagram of General Electric model ATB7 circuit-breaker failures at the San 

Mateo Substation (fig. 1). 

Figure 25.-230-kV bus-support structure at the San Mateo 

Substation (fig. 1). 

Figure 26.-Anchorage failure on 115160-kV transformer 

at the San Mateo Substation (fig. 1). 
ELECTRICAL-POWER SYSTEMS A19 

at the pipe flanges of the upper pipes that support the transformer radiators. The seals had to be replaced to stop the leaking; the transformers were otherwise undamaged. 

No damage was reported in the 115-kV switchyard. In 

the 60-kV switchyard, a bus connection to a disconnect switch 

mounted on the bus-support structure and anchorage to three 

115160-kV transformers were damaged, but transformer operations were unaffected. 

Three problems were noted with items mounted on the 

230-kV bus supports. The top of the 230-kV bus-support structure is shown in figure 25. The rigid bus connection on the 

center phase to the bypass switch on top of the bus failed and 

is not shown. The casting that connects the bus to the switch 

failed, and the bus rotated around the cable until it came in 

contact with the buswork. Porcelain members failed on two 

disconnect switches mounted high on the bus. In two places, 

where the insulators connect the flexible bus to the bus structure, the hook-and-slot attachment disengaged and dropped 

the bus. 

In some disconnect switches, failures of metal connections caused slipping of the rotating action at the base of the 

switch, which normally causes the switch to open. Several 

oil-type circuit breakers and three large synchronous condensers were undamaged. 

Within the 60-kV switchyard, a rigid-bus connection 

between flexible bus and a disconnect switch on top of the 

bus-support structure failed similarly to the one described 

above. Anchorage of one of two banks of the skid-supported 

115160-kV transformers failed, as shown in figure 26. The 

old, grouted-in-place anchors failed, but transformer operation was unaffected. 

MONTE VISTA SUBSTATION 

The Monte Vista Substation has a 230-kV switchyard 

adjacent to a 115-kV switchyard and a 60-kV switchyard located about half a mile away. All three switchyards are in the 

hills below Monte Bello Ridge just west of Cupertino, about 

11 mi from the earthquake epicenter (fig. 1). The nearest 

strong-motion-recording instrument, about 6 mi away in 

Saratoga, recorded a peak ground acceleration of 0.34 g. 

The 230-kV switchyard at the Monte Vista Substation 

has three 230-kV circuits from the Metcalf Substation and 

two to the Jefferson Substation. Two transformer banks provide power to the 115-kV bus and one bank provides power 

to the 60-kV bus. 

The porcelain member of a CCVT on a 230-kV line at 

the Monte Vista Substation failed, as shown in figure 27. Post 

insulators that supported transfer buses on top of the bus-support structures above two transformer banks failed. One intact transfer bus and one transfer bus resting on top of the 

bus-support structure, with post-insulator supports missing, 

are shown in figure 28. On an adjacent bus-support structure, 

one phase was intact, and one phase was missing. Part of the 

post-insulator support can be seen at the top of figure 28. 

Note that all loads that restrain torsion of the bus-support structure would be carried by the post insulators which support 

the transfer buses. In some places, the transfer bus fell across 

the phases of the circuit. In one place, this failure damaged a 

bell on an insulator string that supported the bus; the bell was 

replaced. 

A 230-kV lightning arrester supported on a 23011 15-kV 

transformer failed at its base. One single-phase 230160-kV 

transformer was damaged internally. An isolated bus-support 

pad was damaged when expansion anchorbolts shattered the 

top of the pad. All other bus supports had cast-in-place anchors and were undamaged. The bus connections to several 

disconnect switches were misaligned, apparently owing to 

shifting of individual bus members; whether this misalignment affected the switch operation is uncertain. 

Two relatively new BBC three-phase dead-tank circuit 

breakers, 1 15 and 230 kV, were undamaged. No live-tank circuit breakers were located in the switchyard. 

Figure 27.-Damaged capacitatively coupled 

voltage transformer at the Monte Vista Substation (fig. 1). 

Figure 28.-Bus-support structure and transfer buses at the Monte 

Vista Substation (fig. 1). 
PERFORMANCE OF THE BUILT ENVIRONMENT 

NEWARK SUBSTATION 

The Newark Substation is located at the southeast end 

of the bay, about 33 mi from the earthquake epicenter. Gaskets on live-tank circuit breakers leaked. 

LOS BANGS SUBSTATION 

The Los Bafios Substation is 7 mi west of Los Bafios, about 

47 mi from the earthquake epicenter (fig. 1). Strong-motion 

records from Los Bafios Game Preserve and San Luis Reservoir show about the same peak ground acceleration as those 

from the 1984 Morgan Hill, Calif., earthquake-about 0.05 g. 

In the 1989 Loma Prieta earthquake, the substation was undamaged, whereas in the Morgan Hill earthquake, three phases 

of 500-kV circuit breakers were severely damaged, and nine 

others were somewhat less damaged (Schiff, 1985). Rigid connections between current transformers and circuit breakers 

were replaced with flexible connections after the Morgan Hill, 

Calif., earthquake. Evidence was observed that these rigid 

connections contributed to the damage in that earthquake. 

EARTHQUAKE DAMAGE TO THE 

POWER-DISTRIBUTION SYSTEM 

Relatively little damage to the power-distribution system was reported. Throughout most of the earthquake-affected area, aerial distribution is used. Many lines were 

downed, and thousands of fuses in distribution feeders were 

blown. Some pole-mounted distribution transformers fell 

from their poles. Slots in the transformer-mounting brackets 

slide over the heads of bolts that extend through the poles 

and are secured by nuts. Seismic loads and, possibly, age 

deterioration allowed the damaged transformers to slip off 

the bolts and fall. Several 4-kV transformers were severely 

damaged when 12-kV lines strung above the 4-kV lines fell 

and came in contact with the 4-kV lines. From 50 to 75 transformers were damaged, and replacements had to be trucked 

in from storage. Crossarms broke on some poles. Several 

poles fell over because of rotten bases, and some sound poles 

broke. Many poles in the Santa Cruz Mountains were lost 

because of landslides. 

Within downtown San Francisco and parts of the Marina District, underground power distribution is used. Transformers generally are mounted in vaults or on pads and 

restrained at comers by 4.5-in. angle brackets, which are bolted 

to the pads. No problems were discovered with the transformers bolted to pads. In the Marina District, vaults for two 12- 

kV vault transformers appeared to have floated to the surface, 

and conduits to vaults were broken. Many conduits were broken, but the conditions of cables are uncertain. Less damage 

was reported to conduits in the Marina District than originally expected. 

At the Delphin Substation near Santa Cruz, the anchorage of three single-phase transformers failed, allowing motion that caused arcing. Service at the substation was still 

totally disrupted at the time of our site visit on October 20, 

1989. Some soil liquefaction apparently occurred at the site. 

In general, the overall damage to the power-distribution 

system in the San Francisco Bay region was characterized as 

being similar to that from a severe winter storm of a magnitude that may occur once a year. 

REFERENCES CITED 

Schiff, A.J., 1973, Earthquake effects on electric power systems: 

American Society of Civil Engineers Proceedings, Power Division Journal, v. 99, no. 2, p. 317-328. 

1985, The Morgan Hill earthquake of April 24, 1984-investigation of lifelines: Earthquake Spectra, v. 1, no. 3, p. 615- 

632. 

1989, Lifeline response to the Tejon Ranch earthquake: Earthquake Spectra, v. 5, no. 4, p. 791-812. 

Stepp, J.C., ed., 1990, Industrial facilities, chap. 7 of Benuska, Lee, 

ed., Loma Prieta earthquake reconnaissance report: Earthquake 

Spectra, v. 6, supp. 90-01, p. 189-238. 

APPENDIX: EMERGENCY POWERENGINE GENERATORS 

The earthquake performance of emergency generators 

was generally poor, particularly when the importance of these 

systems is taken into account. In addition to some power facilities, emergency generators are typically found in critical 

facilities, such as hospitals and emergency operation centers. 

This appendix identifies the common failure modes for engine generators and gives installation criteria, as well as discussing maintenance problems. 

FAILURE MODES 

The following failure modes are commonly observed in 

engine generator systems. 

Failure of vibration isolators.-Rotating equipment is 

commonly mounted on vibration isolators to isolate the engine vibrations from its support structure. When subjected to 

ground excitations, the supported equipment typically undergoes a large-amplitude response, causing it to damage the 

isolator. Some isolators made of brittle materials, such as cast 

iron, can fail possibly causing the unit to move excessively or 

tip over. 

Failure of batteries.-Batteries are commonly required 

to start the emergency-power system. These batteries are commonly damaged because they and (or) their rack are inadequately secured, cells impact restraints or other cells and 

crack cases, slack is not provided in the electrical connec- 
ELECTRICAL-POWER SYSTEMS A21 

dons to accommodate relative displacements, or the battery 

rack collapses. 

Failure of utility connections.-Failure of one or more 

of the numerous "utility" connections (cooling-heating water, fuel line, powerline, oil line) can disrupt system operation and the flow of power. 

Failure of day and storage tanks.-The day tank, which 

contains a small amount of fuel and is located near the engine 

generator, is commonly unanchored, allowing it to move or 

tip over. The fuel lines can break, stopping the engine and 

creating a fire hazard. The main fuel-storage tanks can move 

and break connections. Tanks on legs made of steel angles 

commonly fail, and horizontal tanks not anchored to their 

saddles can slide and break fuel-line connections. 

Failure of cooling system.-Some engine-generators 

have a remote cooling system because of the location of an 

engine generator. The cooling tower or coils commonly are 

unanchored, and waterlines can break. Makeup water is 

needed if evaporative-cooling towers are used. 

Failure offlexible coupling.-The flexible coupling provided between the engine and the generator can fail as a result of excessive relative deflections between the units, because 

each unit has its own independent support structure. 

OPERATING AND MAINTENANCE ISSUES 

Engines may fail to start because air dampers have not 

been opened, cooling water is not turned on, batteries are 

old or run down, diesel fuel is old and fouled, or fuel filters 

or injectors are clogged. Engines have failed when units were 

not tested under full load or when relays that sense a power 

outage failed to operate. The load to be carried by the generator commonly increases between the time of its design 

and the time when it is needed, and so generator capacity 

may be inadequate. 

INSTALLATION GUIDELINES 

On the basis of observations from this and other earthquakes and the inspection of engine generators, the following guidelines are provided to help ensure engine-generator 

reliability. 

The equipment should be rigidly mounted to its foundation-Most of the failures noted above would have been 

eliminated if the equipment were rigidly mounted to its foundation. If vibration isolators are necessary, units with castiron components should be avoided. Seismic performance 

can be improved by providing the engine generator with snubbers to prevent excessive motion. Anchorage adds little to 

the cost of installation and should be very conservative. Expansion anchors are not recommended for vibrating loads. 

Cast-in-place or grouted anchors designed for ductile failure 

should be specified. 

Batteries should be firmly secured to their racks.-Securing batteries to their racks prevents them from falling off 

the rack or vibrating against each other. Stiff foam spacers 

should be placed between cells and cell restraints to prevent 

impacting. The rack must be anchored and braced, so that it 

can support the substantial battery weight. 

Interconnecting utilities should be provided with adequate flexibility and slack.-Utilities for units mounted on 

vibration isolators should be provided with slack in the connections to accommodate the motion allowed by the isolators. 

The day tank should be adequately secured.-At many 

installations, the day tank is added almost as an afterthought 

and is commonly supported by flimsy straps. Furthermore, 

the tank itself may be poorly constructed. The tank, its supports, and, in particular, the connections should be able to 

support a force in any direction equal to twice the tank's 

weight when full of fuel. Fuel-storage tanks should be anchored. 

The unit's cooling system should be self-contained.- 

Cooling systems consisting of a radiator mounted to the engine generator skid have performed well in earthquakes. If 

an external cooling system is required, its anchorage and the 

security of the water system should be evaluated. If evaporative cooling is used, an emergency supply of makeup water 

should be available because the normal water supply may be 

disrupted. 

Engine and generator mounts should be integral.-To 

prevent misalignment of the engine and generator, their 

mounts should be secured to the same support structure. 

Personnel should be provided with starting instructions.-Instructions for starting the engine should be posted 

so that if problems arise, available personnel can start the 

engine. Such critical items as opening dampers and coolingsystem valves should be noted. Maintenance should include 

checking batteries (acid level, specific gravity, charging, age), 

cleaning fuel filters, and replacing old fuel (fuel should not 

be older than five years). Units should be periodically tested 

under full load. The relay to sense a power outage should be 

checked carefully for corroded contacts. 

Seismic specifications should be issued for new installations.-Installation specifications for new equipment 

should be called out on engineering drawings, and equipment should be inspected in the field to ensure that these 

specifications are followed. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

COMMUNICATION SYSTEMS 

By Anshel J. Schiff, Precision Measurement Instruments and Stanford University; 

Alex Tang, Nortel Canada, Inc.; 

Lawrence F. Wong, Pacific Bell; 

and 

Luis Cusa, Los Angeles Department of Airports 

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ABSTRACT 

Immediately after the earthquake, the public switched 

network was difficult to use because of congestion caused by 

a huge increase in traffic volume. Dialtone delays were as 

long as 3 minutes. Congestion during business hours continued to be a problem for 4 days after the earthquake. 

Relatively little damage to central-office telephone 

equipment was reported. Commercial power in the earthquake-affected area was generally lost. In three central offices, problems were reported with the engine generators used 

to recharge batteries. In all but one central office, replacement generators were obtained before the batteries discharged. At one central office, three of the five switches had 

to be shut down to conserve power until a replacement generator could be obtained. The trade literature reported acid 

spills, indicating that some batteries failed. 

The most significant and costly damage was to a large 

building in Oakland that housed Pacific Bell and AT&T facilities. The building was severely damaged structurally, and 

all but essential personnel were evacuated. A water tank that 

supplied makeup water for the air-conditioning cooling tower failed, and so air-conditioning capacity was limited. The 

building was extensively seismically upgraded after the earthquake. Except for a brief interruption in the operation of the 

enhanced public-safety communications (9 1 1) system, telephone equipment in the building continued to operate. 

The performance of the cellular-telephone system was 

mixed. Some system damage was reported, but many cellu- 
A24 PERFORMANCE OF THE BUILT ENVIRONMENT 

lar-telephone sites have limited reserve power when commercial power is lost. Users in some areas indicated that service 

was good, while in other areas service outage was reported. 

Cellular-telephone sites can have congestion problems when 

demand exceeds capacity. Because of problems with the public 

switched network, both the number and use of cellular telephones increased, and performance degraded over time as the 

use increased. 

The 91 1 system had many problems. Congestion of the 

telephone system made it difficult to get though to publicsafety answering points (PSAP's). Several PSAP's had their 

own problems. Some centers lost power, and their display 

panels could not indicate which lines were ringing or which 

were busy. Because of the long delay in getting a dialtone, 

even on essential-service lines, transfer of a call to the appropriate agency took much longer, and so fewer calls could be 

handled. In smaller offices, the operator also dispatches emergency-response services, such as fire, rescue, and police. Dispatching is done by radio, but because repeaters were not 

functioning, some vehicles to be dispatched could not be 

reached. In severely damaged areas, the resources available 

to the dispatcher were quickly depleted, and so immediate 

response to calls could not be made. 

Generally, radio-communication systems worked well, 

except when repeaters were needed. Repeater sites are located on many hilltops in the earthquake-affected area. Many 

repeaters had only limited emergency power, and so a few 

hours after commercial power was lost, the repeaters shut 

down. The emergency power at several repeater sites failed. 

The equipment at some repeater sites was damaged because 

of severe ground motion at the sites and poor seismic design 

and installation practices. Amateur-radio support personnel 

played an important role in providing the only means of communication or in supplementing telephone-system communications at local emergency-operation centers. 

Figure 1 .-Cable-tray hardware used in communication equipment. 

INTRODUCTION 

The communication systems considered here are telephone systems, cellular telephone systems, private radio systems, and amateur-radio operators ("hams"). Radio and 

television broadcast media and newspapers are discussed by 

Rapaport (this chapter). Because of the many communities 

affected and the range of communication systems involved, 

we could not canvas each medium in the entire earthquakeaffected area. 

TELEPHONE SYSTEMS 

LONG-DISTANCE NETWORKS 

Long-distance telephone service in the earthquake-affected area is provided primarily by AT&T; MCI and U.S. 

Sprint also provide service. Long-distance carriers can block 

or limit access of long-distance calls to and from specific areas codes through network-load balancing, which frees up 

circuits for use within an area code. 

Telephone traffic worldwide increased significantly as a 

result of the earthquake. For example, between 5:00 and 9:00 

p.m. P.s.t. October 17, the AT&T network attempted 40 million worldwide calls, in contrast to the usual 18 million, although only a fraction of these calls were completed. On the 

next day, 27.8 million calls were attempted to the 408 and 

415 area codes that serve the earthquake-affected area. Only 

9.5 million calls were completed, still representing almost a 

threefold increase over the normal daily volume of 3.5 million. 

Calls to the 408 and 415 area codes were blocked by 

long-distance carriers and Pacific Bell on October 18 and 19 

to improve service within the earthquake-affected area. On 

October 18, 70 percent of outbound calls and 30 percent of 

inbound calls were completed on AT&T systems. Telephone 

representatives cited recent large-scale introduction of technical innovations, such as the use of digital switches and optical fiber, as reasons for being able to carry the high volume 

of calls. Long-distance telephone networks apparently were 

unaffected by seismic damage to equipment or technical problems. 

The press reported that residents in the 408 area code 

could not call a nearby hospital, which was located in the 415 

area code, because of long-distance blocking. However, it was 

not long-distance blocking that caused this problem, because 

calls between different area codes that are close to each other 

do not use long-distance carriers and thus are not subject to 

long-distance blocking. The problem is that callers served by 

a different central office than the hospital's would have difficulty getting through. The solution to this problem is for the 

hospital to be served directly by some lines from the nearby 

central office, a technique known as "dual homing." This so- 
COMMUNICATION SYSTEMS A25 

lution, however, has additional costs for connecting a line to 

another central office, and more than one central office may 

be required. 

EARTHQUAKE DAMAGE TO 

LONG-DISTANCE-NETWORK FACILITIES 

In one Oakland facility, support clips failed on several 

heavily loaded cable trays, which were part of the AT&T system, so that the trays sagged about 1 ft. Also, friction clips 

used to connect cable-tray sections slipped, allowing cabletray sections to separate and in some places to sag. The function of the cables in the tray, however, was unaffected. 

Cable-tray hardware is unique to communication equipment 

(fig. 1). Pacific Bell has improved hardware details by adding pins that provide a positive connection to the friction clips; 

however, the less reliable clips are used in communication 

equipment by telephone and industrial companies in California and other parts of the country. Overloaded cable trays 

aggravate these problems. No damage to switches or other 

communication equipment used by long-distance carriers was 

reported. 

LOCAL TELEPHONE NETWORKS 

Local telephone service in the earthquake-affected area 

is dominated by Pacific Bell. Gilroy is served by Continental 

Telephone, and Los Gatos by General Telephone (GTE). 

ESSENTIAL-SERVICE LINES 

The switch in the central office that routes calls can handle only a fraction of the lines that are connected to it at any 

one time. The central office takes advantage of the fact that 

only a few lines are normally active at any time. After a major earthquake, telephone usage increases dramatically, and 

the switch cannot immediately handle all of the requests for 

service. As a result, a user may have to wait for a dialtone 

before making a call. Under extremely heavy loads, this delay can be as long as several minutes. However, most users 

are unaware that if the telephone system is undamaged, those 

who wait for a dialtone can eventually make a call. Telephone 

companies have developed procedures and equipment that 

give a high priority to lines for essential services, such as 

police departments, hospitals, and government and selected 

emergency-operations centers (EOC's). Users who satisfy 

certain criteria can get essential-service lines. For example, 

all of Pacific Bell's pay telephones are essential-service lines. 

The operation of essential-service lines is unclear; telephone 

personnel described two methods used. In the first method, 

calls using essential-service lines go to the head of the queue 

for calls requesting service. In the second method, when demand for service exceeds a preestablished load threshold, lineload control is automatically invoked by the switch, so that 

essential-service lines do not have to wait for a dialtone. According to this method, the excess capacity in the switch is 

used to handle non-essential-service lines on a rotating basis. 

POSTEARTHQUAKE OPERATION OF 

ESSENTIAL-SERVICE LINES 

For reasons that are not entirely clear, the operation of 

essential-service lines did not operate as expected in the earthquake because line-load control was generally not activated. 

As a result, essential-service lines commonly had dialtone 

delays of 10 to 15 s, significantly affecting public-safety-communication (91 1)-system operations when operators had to 

transfer calls to other agencies. This delay may have led some 

91 1 operators to believe that they could not make outgoing 

calls. The inability to make outgoing calls was reported at 

two emergency-communication centers, even though all telephone equipment reportedly was functioning normally. In 

Sacramento, where no earthquake damage occurred, a 1- 

minute dialtone delay on an essential-service line was reported, at which time the caller abandoned the call and used a 

radio to get through, suggesting that line-load control should 

have been, but was not, activated. 

At an office in Oakland, the computer that provides the 

enhanced 9 11 system with automatic address-location information for northern California shut down for about 15 minutes, without affecting the basic operation of the 9 1 1 system. 

EARTHQUAKE DAMAGE TO 

LOCAL-TELEPHONE-NETWORK FACILITIES 

Although damage to Pacific Bell's communication equipment was minor and did not significantly affect service, the 

loss of commercial power did cause some problems in three 

central offices. All but one of Pacific Bell's 160 central offices worked throughout the disaster without impairment. Central offices contain batteries to operate the telephone system 

for several hours in case commercial power is lost. In addition, the central offices have engine generators to recharge 

the batteries, so that telephone service can be maintained for 

2 to 21 days without commercial power and without refueling. However, some problems with engine generators were 

reported. In one central office in San Francisco, asbestos was 

being removed from the room that contained the engine generator, putting the generator out of service. A rented generator, located outside the building, served as a replacement 

during the remodeling. This generator failed to start, and 

workers found and replaced a clogged fuel filter. The generator then started, but it would not carry load and eventually 

caught fire. A replacement generator was obtained before any 

disruption of service occurred at the central office. In anoth- 
A26 PERFORMANCE OF THE BUILT ENVIRONMENT 

er central office, which has diesel- and turbine-powered generators, the turbine-powered generator had a faulty governor 

that caused fluctuations in speed, and so it had to be taken out 

of service. A cooling-system water pump for the diesel engine was shut off, and the diesel engine shut down automatically when it overheated. Partial service was maintained by 

shutting down parts of three of the five switches at the central 

office until additional backup power could be obtained. At 

the central office in Hollister, an engine generator could not 

be started. A replacement generator was obtained before it 

was discovered that a damper, used to shut off the air intake, 

was closed. 

In San Jose, two circuit packs (circuit boards used in 

telephone equipment) came out of their motherboard sockets in the earthquake, similar to occurrences in Long Beach, 

Calif., during the 1987 Whittier Narrows, Calif., earthquake, 

also in an area of relatively low amplitude shaking. In the 

1985 Mexico City earthquake, numerous circuit packs fell 

from equipment. 

In Oakland, a major facility that contained Pacific Bell 

and AT&T equipment was severely damaged structurally, but 

no significant damage to communication equipment was reported. On the roof, a water tank that supplied makeup water 

for a cooling tower used in the air-conditioning system was 

damaged, but cool weather made the tank water unnecessary. 

In light of the short duration and small bedrock motion in this 

area from the earthquake, it can be speculated that more severe ground motions could have caused the loss of the building. Had this loss occurred, communications in northern 

California would have been severely disrupted for a long time. 

At a Pacific Bell building in Watsonville, peak ground 

accelerations of 0.39 g and roof accelerations of 1.24 g were 

recorded by instruments maintained by the California Strong 

Motion Instrumentation Program of the California Division 

of Mines and Geology. The structure and the equipment that 

it housed were undamaged. No damage to trunklines or user 

looplines was reported. Even in the Marina District of San 

Francisco, where liquefaction occurred, buried telephone 

vaults did not crack or float to the surface. 

In Gilroy, which is served by Continental Telephone, no 

damage to telephone equipment was reported. The electronic 

switch (AT&T 5 ESS), which was anchored to the floor and 

braced to a wall, pulled its wall anchorbolts from the wall. 

Commercial power was briefly interrupted, but a diesel generator operated. The long disruption of commercial power in 

the Hecker Pass and Summit Road areas, in the hills west of 

Gilroy, required portable generators to be brought in because 

these sites had only limited battery backup power. A few service drops to homes were damaged, but service needs were 

not out of the ordinary. 

In the January 2, 1990, issue of Communications Week, 

an industry news magazine, an article based on an internal 

Pacific Bell memorandum described some of the problems 

caused by the earthquake. This article confirmed the problems associated with emergency power discussed above, noting that the central telephone office in Hollister was down for 

6 hours, that "some pretty severe acid spills in some of the 

offices" were reported, and that "they lost international trunks, 

as well as many other services," owing to failure of emergency power at a central office. A Pacific Bell spokesperson interviewed for the article disputed some of the interpretations 

made by the memorandum's author, but not the factual accounts. 

POSTEARTHQUAKE OPERATION OF 

LOCAL TELEPHONE NETWORKS 

On the day after the earthquake, Pacific Bell had a record 

volume of 80 million calls in the nine-county San Francisco 

Bay region (the daily average volume is 55 million calls). As 

a result of the heavy volume, delays in getting a dialtone and 

problems in completing calls were reported. In general, although calls could be made within most local areas, calls between areas served by different central offices or with different 

area codes were more difficult to make. Although many telephones were reported to be not working, most of them were 

actually working, but users thought that they were not because of the delay in getting a dialtone or problems with private branch exchanges (PBX's). In many areas, telephone 

service degraded during peak-load times in the morning and 

afternoon for several days after the earthquake. Service announcements on the radio immediately after the earthquake 

requested that only emergency calls be made; these announcements were, at best, only minimally effective. 

The operations of the emergency-response community 

were impaired by communication problems, but generally 

the emergency response worked well. The overall good performance of the emergency response is partly attributable to 

the moderate intensity of shaking in most high-populationdensity areas. The emergency-response community was not 

significantly overextended, and many of the problems confronting regional EOC's were associated with an abundance 

of aid and supplies, rather than shortages. 

In Gilroy, the electronic switch was saturated for a few 

minutes after the earthquake; however, it remained operational. At the request of Pacific Bell, line-load control was imposed by Continental Telephone to limit calls being transferred 

to the 408 area code to every other call. Although the Gilroy 

switch was physically capable of implementing essential-service lines, Continental Telephone does not use that feature. 

GTE provides service to Los Gatos, Morgan Hill, and 

nearby mountain areas. Six central offices and several smaller facilities in the mountains serve the area. Commercial power 

was lost, but emergency power operated, except in Los Gatos, where a diesel generator stopped when the day tank ran 

out of fuel. The pump that supplies the day tank from the 

main tank did not work, and repair took about 3% hours. Essential-service lines were jumped to a trunk at another central office for service; however, the 91 1 system still had problems. 
COMMUNICATION SYSTEMS A27 

It should be noted that GTE operates its essential-service lines 

differently from those described above: Essential-service lines 

are given only assurance of service, not special dialtone priority; thus, essential-service lines must compete for dialtone 

with all other lines. Some of the mountain areas have stations 

with batteries that last 8 hours; emergency generators were 

provided to these areas. Some parts of the telephone system 

were without power for 4 days. No equipment problems were 

reported. It took about 3 days before fast dialtone response 

returned. 

CENTRAL-OFFICE CENTREX SYSTEMS 

Several organizations use the Centrex system for communications. Centrex is a trademark for a group of features, 

and similar packages are offered under different names. With 

this communication system, telephoning within an organization involves dialing only four or five digits, but the switching is typically done at a telephone company's central office, 

rather than by a PBX located at the organization site. When 

the switch in the central office is overloaded, a long wait for 

a dialtone may be noticed, even for a call within the organization. In situations where facilities of the organization are 

separated and served by different central offices, a second 

delay may occur when transferring a call to the second central office. Dialtone delays for a Centrex system are due to 

the load on the switch in the central office and not necessarily to activity in the organization using the system. Getting a 

dialtone quickly is of vital importance for telephone systems 

in critical facilities, such as hospitals, where good internal 

communications are needed for efficient operation. If a PBX 

is used instead of Centrex, it must be selected so that it can 

handle extreme loads within the facility. 

PRIVATE BRANCH EXCHANGES 

A more common cause of disruption of the telephone system within organizations was the lack of emergency power for 

PBX's, which are the privately owned telephone systems used 

by companies and large organizations for telephone service 

within a facility or an organization. PBX's also connect to outside lines provided by the local telephone company. When 

commercial power is lost, many of these systems have limited or no emergency-power capabilities, and so all or most of 

the telephones in a given office or an entire building will not 

operate. Commonly, users are unaware that the problem is 

with the PBX and assume that the commercial carrier's system is not working. It is important for people to know that 

emergency calls can generally be made from pay telephones 

or adjacent offices which are not run by the same PBX. 

Some damage to smaller PBX systems was reported. 

These systems have many manufacturers, not all of whom 

have developed equipment that is as seismically rugged as 

traditional telephone equipment. Also, many PBX's may not 

be installed with the same attention to seismic hazards that 

telephone-company equipment receives. 

CELLULAR TELEPHONES 

Cellular-telephone systems consist of an array of transceivers (radio transmitters and receivers) called cells; these 

cells communicate to subscribers' mobile telephones (cellular telephones) and are connected through leased lines, private lines, and microwave links to a switch operated by the 

cellular-telephone company. Larger companies may have several switches, which are typically connected to each other by 

communication lines of the cellular-telephone company and 

to the central office of the local telephone company. The link 

that connects the cellular switch to the public telephone system is similar to a central office, and so it generally has better 

access than does an individual subscriber. In each area, cellular-telephone service is typically provided by two cellulartelephone companies: users can subscribe to both companies 

to enhance the reliability of their cellular telephone. Typically, each cell transceiver has battery backup power and may 

have engine generators; however, due to space limitations, 

backup power may be limited. Each cell is monitored, and 

losses of commercial power, low batteries, and generator failures are logged at a service office to facilitate maintenance. 

The cellular-telephone-company switch completes calls 

between cellular-telephone subscribers connected to the 

switch, without entering the regular telephone system. The 

response time for intracellular telephones depends on the traffic load that is placed on the cell and the switch that serves it. 

The number of calls that a single cell can handle simultaneously depends on the cellular equipment but typically ranges 

from 15 to 60. Most of the switches used by cellular-telephone companies can assign a high priority of service to some 

of their subscribers. With most of these systems, high-priority users go to the head of the queue in the cellular-telephone 

company's switch. However, these features were not implemented on cellular-telephone systems in the San Francisco 

Bay region. The National Communications System has petitioned the Federal Communications Commission to authorize a nationwide Cellular Priority Access System (CPAS) 

for emergency responders. 

For cellular calls to telephones outside the switch's service area, private lines may be used to connect to another telephone-company switch, or the public-telephone system must 

be entered. Processing of the call would then be the same as 

for any telephone user. It should be noted that the service 

areas of adjacent cells overlap, and so the loss of a cell may 

not prevent calls from within that area from being completed. 

Some conflicting reports about the operation of cellular 

telephones were received shortly after the earthquake. Some 

reports claimed that their cellular telephones worked much 

better than wireline telephones, whereas others said that us- 
A28 PERFORMANCE OF THE BUILT ENVIRONMENT 

ers were unable to complete cellular-telephone calls. Calls 

completed within a cellular switch will depend on the load 

on the switch and the capacity of the switch relative to its 

customer base. The load on each of the switches that must 

handle the call always influences the response time. One problem with adding telephones just after an earthquake to supplement communication capabilities at an organization (such 

as an EOC) is that the cell serving that area may become 

saturated, thereby degrading the service provided to all cellular-telephone users in the area. 

One company with four cellular switches lost power to 

a cell located on Loma Prieta peak. The generator failed to 

start, but a new engine-circuit-control card, installed the next 

morning by a crew flown in by helicopter, corrected the problem. Another cell, located in a building that was condemned 

because of structural damage, continued to function. 

In Los Gatos, cellular-telephone service from one company was unavailable for about half an hour, and then service 

became intermittent. Reports indicated that microwavecommunication antennas were misaligned. An equipment 

rack for one of the cellular-telephone companies on the fourth 

floor of a major communications building in Oakland pulled 

expansion anchors from a wall, tipped over, and caused a 

short circuit, which blew a fuse. A recording head on one of 

two computer disks mounted in an equipment rack crashed, 

damaging a sector of a disk; the disk was reformatted and 

continued to operate. 

PUBLIC-SAFETY 

COMMUNICATION (911) SYSTEM 

The public-safety communication system, commonly 

referred to as the 91 1 system, is the primary means for individuals to obtain emergency services, such as police, fire, and 

medical assistance. The system consists of public-safety ans wering points (PS AP's), which have operator positions (consoles), radio-communication capability, a tape system to 

record all calls, and emergency backup power. Some PSAP's 

also have a computer-aided dispatch system that logs dispatches and indicates the disposition of units on the basis of data 

provided by the PSAP. Typically, each county has a PSAP 

that receives emergency calls from unincorporated areas within the county and from communities that do not have their 

own PSAP. Some county emergency-communication centers 

have as many as 60 operator positions, and police, medical, 

and fire dispatchers may be located in the same facility. In 

other areas, sheriff's departments operate the system, and 

many cities have their own PSAP's. Most PSAP's have enhanced 9 1 1 systems, with automatic address-location and telephone-number information: The PSAP operator has a display 

that shows the address and telephone number of the calling 

party, and the system logs the calls. Within California, 92 

percent of the State is served by enhanced 91 1 service. 

In larger county 9 11 systems, which may have as many 

as 30 operator positions, an operator will receive a call, identify the appropriate response agency (fire, police, or medical), and transfer the call to a dispatcher for that agency. In 

smaller emergency-communication centers, such as those for 

a city, which may have as few as two operator positions, the 

operator also serves as a dispatcher. In a location where the 

sheriff's department operates the 9 1 1 system, police calls will 

be dispatched, and fire and medical calls transferred. 

PSAP's typically do not use amateur-radio emergencycommunication resources, but EOC's have integrated them 

into their system and commonly make extensive use of their 

resources. 

Interviews were conducted with 15 emergency-cornrnunication centers, EOC's, and emergency-response organizations, 

primarily by telephone. These interviews were conducted 5 to 

10 weeks after the earthquake, and some of the individuals 

interviewed had not been at the center during the emergency-response period. Some individuals dealt primarily with 

public relations and could not provide the technical details 

requested, and others had been so busy at the time of the 

earthquake that they could not recall many details. Some 

organizations were called twice: First, a dispatcher was interviewed, and then a followup call was made to the head of 

the agency. Commonly, agency heads reported fewer problems than did the dispatchers. 

The most serious and most common problems were related to the inability of many emergency-communication centers to make long-distance calls, for example, to area codes 

408 and 415, which were blocked by network-load control, 

and to area codes 916 (Sacramento, Calif.) and 202 (Washington, D.C.). Another serious problem was the difficulty in 

calling numbers within the same area code that are served by 

different central offices. At some centers, delays in getting a 

dialtone were reported, even on essential-service lines. For 

this reason, the centers could not transfer calls to the appropriate agencies, and they had to use radio or ring-down lines; 

because this procedure is much slower, fewer incoming calls 

could be handled. 

Various problems associated with emergency power were 

reported. At some sites, the emergency power is derived from 

an engine generator, and a pause of 10 to 30 s occurs after 

commercial power is lost before emergency power is available. With the loss of power, display panels go black, and so 

it is impossible to know which line is ringing, even though 

the telephones are working. Several emergency-communication centers did not have uninterruptable power supplies for 

their computer-aided dispatch systems, and so they had to 

revert to backup paper messages. 

In smaller centers, where the operator normally also does 

the dispatching, another individual did the dispatching to allow the operator to answer more calls. In severely damaged 

areas dispatchers worked from 12 to 14 hours per day, and 

food and drinks were needed to sustain them; however, wa- 
COMMUNICATION SYSTEMS A29 

ter supplies were disrupted, and food at local grocery stores 

was almost gone before the initial bedlam had subsided 

enough to allow time for the dispatchers to shop. At several 

centers, repeaters used for radio communication were inoperative or worked only intermittently. This failure generally 

did not cause any serious problems because remaining repeaters gave adequate coverage; when they did not, dispatches 

were made directly to emergency responders, without the 

use of repeaters. 

The responses of several PSAP's and EOC's are given 

below. 

CALIFORNIA OFFICE OF 

EMERGENCY SERVICES EOC 

The California Office of Emergency Services (OES) lost 

power for about 2 hours, but emergency power worked without problems. Telephones became saturated during peak 

hours for about a week after the earthquake. One to five hams 

were available around the clock for 4 days; they were primarily used when the telephone system became saturated at peak 

hours during the day. 

nels. (A "shadow" is a ham who travels with a fire chief or 

other official and provides independent radio communications to that individual.) The PSAP received about 40 to 50 

calls in the first four hours. Most calls concerned actual or 

suspected gas leaks; several calls were related to downed 

powerlines and medical needs. Four fires were reported: two 

were grass fires started by downed powerlines, and two were 

structural fires of unknown origin. There were adequate firefighting resources; however, the three regular units were supplemented by three volunteer units. 

LOS GATOS PSAP 

Outgoing telephone calls GTE could not be made from 

the Los Gatos PSAP for 4 hours after the earthquake. During this time, operators used radio communications to contact agencies. At the EOC, hams were on duty 24 hours a 

day until November 1, 1989, to coordinate with the American Red Cross and shelters. Hand-held radios were in short 

supply for the additional police who were mobilized. 

GILROY PSAP 

SAN FRANCISCO PSAP 

Commercial power was out for about 3 days at the San 

Francisco PSAP. After a short delay, the center's emergency 

power came on, but there was concern throughout the period 

that it might fail. The computer-aided dispatch system was 

down because of a power outage, and the 15 operator positions were saturated with calls. Problems with transferring 

calls to other agencies, whose lines were often busy, were 

reported. The ring-down lines worked (ring-down lines go 

through the telephone company's central office but not 

through the switch), but information had to be relayed over 

the telephone because ring-down calls cannot be transferred; 

therefore, the dispatch process was unusually slow. The ratio of dispatches to calls received was especially low. 

SANTA CLARA SECONDARY PSAP 

The Santa Clara secondary PSAP, which is operated by 

the California Division of Forestry, receives fire calls transferred to it from the Santa Clara County PSAP. Commercial 

power was out for 2 hours at this PSAP, but emergency power worked well. Essential-service lines worked well, but there 

was a 2- to 3-minute delay in getting a dialtone on non-essential-service lines. This situation improved around midnight, but by 7:00 the next morning telephone lines were 

again saturated. Four hams were on site for 48 hours: two to 

operate radios and two to serve as information officers. Three 

or four amateur-radio operators were also used as "shadows" 

with mobile units to reduce the load on regular radio chanCalls could not be placed from the Gilroy PSAP until 

midnight October 18, after which only intermittent calls were 

able to get out. The hams were very helpful; PSAP operators 

could not have gotten through to the appropriate agencies 

without them. A delay in dialtone on essential-service lines 

was reported. Although resources were not depleted, volunteer police and fire fighters came in to supplement regular 

crews. Most calls were related to gas leaks at water heaters 

and meters; however, no fires were reported. 

HOLLISTER PSAP 

Commercial power was off for 3 days at the Hollister 

PSAP. Although the emergency generator worked, it stopped 

periodically for short periods, apparently owing to overload. 

On the second day, the Pacific Gas and Electric Co. (PG&E) 

brought in a portable generator to supplement the main unit 

thereby solving the problem. Long-distance calls could not 

be made from either the PSAP or the EOC, except on one 

line from San Juan Bautista, which was in constant use by 

EOC personnel. The PSAP could not communicate with the 

ambulance unit, even though the unit was nearby. Owing to 

the heavy police load, PSAP operators could not dispatch 

the public-works crews. The radio repeater used by the dispatcher did not have emergency power, and so it was out of 

service until commercial power was restored 3 days after the 

earthquake; this failure may have contributed to communication problems. The PSAP had only two operator positions, 

which were unable to keep up with answering calls and dis- 
A30 PERFORMANCE OF THE BUILT ENVIRONMENT 

patching. The PSAP obtained permission for mutual aid, and 

trained dispatchers from Monterey were brought in to answer the telephones while the local operators dispatched. The 

fire department took over their own dispatch from their site. 

One of the most serious communication problems was that 

large gas leaks could not be reported to PG&E. Fortunately, 

no fires broke out. The PSAP was unaware that hams could 

have communicated with some of the key locations it wanted to contact, and it could have installed stations at the PG&E 

service center. 

A resident in the area, who was familiar with the operation of the telephone system, indicated that on a home line 

one would get a dialtone and calls appeared to be ringing but 

there would be no answer, even though the caller knew that 

someone was at the number dialed. This difficulty occurred on 

October 18 and 20 and intermittently on October 19, suggesting that operation of the switch may have been problematic. 

HOLLISTER EOC 

The Hollister EOC used the same emergency power as 

the PSAP. After the earthquake, the telephones did not work 

until midnight. After midnight, the telephones worked only 

intermittently, and delays were reported in getting a dialtone 

on essential-service lines. Hams played an important role, 

providing a van with radio gear. Two hams worked inside 

the EOC, and two in the van. There were not enough telephone lines at the EOC, and so, on the second day, Pacific 

Bell added six lines. The OES is making changes by putting 

a 20-line console into the PSAP, adding an emergency generator to the repeater, and adding generators to other facilities in the county. Permanent radio equipment is being added 

for ham use. 

MONTEREY PSAP 

Monterey County has an integrated 91 1 system that 

serves most of the county from nine positions in Salinas and 

six positions in Monterey. Commercial power was out about 

1% days, but the emergency power worked. Computer-aided 

dispatch was down because of a power outage. The county 

has an independent communication system, which worked 

well because it does not use the switched networks. Commercial telephones were saturated, and the essential-service 

lines had a dialtone delay. Radio-communication channels 

were busy but usable. Repeaters worked, although some secondary units that did not have backup power went down. 

SANTA CRUZ PSAP 

Commercial power was lost for about 2 hours at the 

Santa Cruz PSAP and was sporadic for some time after that. 

Emergency power worked but ran out of fuel during one of 

the subsequent power outages. No dialtone delay was reported, but calls could not be made to the southern part of the 

county because of line or circuit busy signals. Overloading 

of the 9 1 1 system prevented callers from reaching the PSAP. 

During one 25-minute interval shortly after the earthquake, 

radio communications to the ambulances in the southern part 

of the county were inoperative. During another 25-minute 

period, about 2 hours after the earthquake, all power and 

telephones were dead for an unknown reason. Even after telephone communications improved, some areas in Watsonville 

could not be telephoned. As a result of a training program, 

equipment in the PSAP had been secured, and so the tape 

unit and other items did not fall over. Between 5:00 p.m. and 

midnight, more than over 300 callers reported gas leaks. The 

PSAP had an unlisted telephone number for contacting the 

local PG&E office. Several structural fires and grass fires 

were reported, and some mobile homes had fires related to 

gas leaks. Ambulance resources were exhausted in 5 minutes, but no serious injuries were reported, and so individuals were able to provide for their own transportation to the 

hospital. 

SANTA CRUZ EOC 

The Santa Cruz EOC shares power with the PSAP. After the earthquake, calls could not be made to the southern 

part of the county, and so the hospital could not be contacted. At about 8:00 p.m., a call was received from the hospital, 

and its status was then determined. The hospital worked with 

the city EOC. The radio in the hospital, which was part of 

the medical network, went down because a circuit board had 

vibrated loose. The radio remained down for 3 days; however, a hand-held unit was used, although it had limited power. 

The fax machine in the EOC worked well and was especially useful. In addition to the disruption of lifelines to the hospital, a support for the tank that holds the oxygen supply for 

the hospital failed, causing the tank to tilt and break its connections. The hospital used portable oxygen for 3 days while 

the tank was being repaired. 

RADIO-COMMUNICATION SYSTEMS 

There are several types of voice radio-communication 

systems. Many have a base station, which is commonly a 

fixed facility with a high-powered transmitter and a fixed 

antenna. Mobile units can communicate with the base station and with each other. Ultra-high-frequency (UHF) systems are used by emergency-response agencies, such as police 

and fire departments and PSAP7s, as well as by other organizations, including hams and cab companies. Repeater stations, commonly located on hilltops and ridges, improve the 

coverage and range of UHF radios by receiving and retransmitting signals. Other organizations, such as banks, telephone 
- . . 

COMMUNICATION SYSTEMS A3 1 

companies, and cellular-telephone companies, use microwave 

networks and commonly locate their antennas on hilltops to 

maximize transmission range. Most peaks in the San Francisco Bay region host several such antennas. 

Although these hilltops provide good radio coverage, 

they generally are remote, difficult to reach, and subject to 

severe ground motions in earthquakes. Many of these sites 

sustained severe ground motions, and soil failures made access more difficult. An individual on Mount Umunhum reported that he saw the top of the 45-ft-tall power pole, which 

supported the transformer providing power to the transmitters at the site, swing back and forth about 15 ft. The transformer, which was bolted to the pole, fell to the ground after 

tearing loose the steel mounting tabs. At this site, an abandoned, blast-hardened, reinforced-concrete U.S. Air Force 

radar tower was severely damaged. Two 500-gal propane 

tanks that rested in cradles but were otherwise unanchored 

moved, broke their piping connections, and disrupted the fuel 

supply to the engine generator at the site. At this site, emergency power was restored within half an hour; commercial 

power was restored in about 3 days. 

Many radio-communication sites lost commercial power. 

At one site, the emergency generator tipped over and was inoperable; at a second site, the batteries that start the generator 

were dead; and at a third site, the batteries tipped over, broke, 

and spilled acid on equipment. Many sites were without power until commercial service was restored. Many sites have 

only battery backup power, and so, if commercial power is 

off for an hour or two, the transmitter goes off the air. Highelevation repeaters used by hams appeared to be particularly 

vulnerable because they lost about 30 of their 35 systems in 

the earthquake-affected area; however, not all of these repeaters are used for emergency communications. On Mount 

Diablo, a repeater used by hams operating out of OES region 2 was down for about 2 hours because of the failure 

(not earthquake related) of a control board. Pacific Bell's 

facilities, which typically have their own enclosures and 

emergency power, performed well, even where ground motion was very severe. 

Much of the equipment located at hilltop stations was 

damaged. Because some of these facilities are critical, they 

are discussed below together rather than in association with 

a specific facility with a given site. Sites typically have a few 

small structures that contain electronic equipment. At one 

site that served about 30 different antennas, each with its 

own electrical cabinet, all 30 systems were inoperable as a 

result of the earthquake. Only two of the cabinets were anchored, and most were thrown across the room, breaking 

antenna and power connections. Backup batteries fell, broke 

connections, and spilled acid over other equipment that had 

fallen to the floor. One cabinet, though anchored at its base 

and top, leaned over at about 45O, breaking its antenna connection. Although some systems could be restored, many 

needed major repair and were out of service for an extended 

period. Only a few damaged antennas or failures of antenna 

feeds between the antenna and equipment enclosures were 

reported. 

Some important radio-communication facilities were 

disrupted. For example, U.S. Coast Guard Channel 16, the 

emergency channel for ship-to-shore radios, and a radio transmitter for the station at Monterey were down until 10:OO a.m. 

October 18. One repeater used for emergency service was 

lost; it was replaced with a private unit. Two additional units 

were used for emergency service to expand capabilities. One 

or two repeaters were temporarily disrupted by hams who 

objected to their conversion to emergency use, and one repeater was jammed. 

AMATEUR-RADIO EMERGENCY RESPONSE 

Hams are licensed by the Federal Communication Commission to operate within a wide band of radio frequencies 

under five grades of license; higher grades allow access to a 

broader frequency band. Although all frequencies in the 

amateur band are open, some are reserved, by agreement, 

for emergency use. The American Radio Emergency Service (ARES), a ham organization, is organized to provide 

emergency-communication assistance. Three sections of 

ARES are located within the earthquake-affected area: the 

San Francisco, East Bay, and Santa Clara sections. Another 

organization, with many of the same members as ARES, is 

the Radio Amateur Civil Emergency Service (RACES). 

Several amateur-radio networks are in operation. The 

radio equivalent of a telephone modem for use with computers is referred to as a packet system. After the earthquake, 

the utilization of this network varied. Some stations had little or no use, while one handled 4,000 messages an hour. 

As an example of how ARES works, the Palo Alto district has 45 members who live within the district and 10 to 

15 members who live outside the district but work in the 

area. Several sites are set up to accommodate hams: Locations that have provided space and a hookup to a permanently installed antenna include Palo Alto City Hall (EOC), five 

schools, and four hospitals (Stanford University Hospital, 

Childrens Hospital at Stanford University, the Palo Alto Clinic, and the Veterans' Administration Hospital). In city hall, a 

room has been provided next to the EOC, which has a permanently installed radio with backup emergency power. The 

Palo Alto section's emergency-response manual includes 

information on parking, antenna drops, and other important 

details for each location. Hams have their own hand-held 

radios that, with the facility's antennas, can have a direct 

range of about 3 mi; however, a local repeater extends the 

range to 20 mi. Mountaintop repeaters have longer ranges, 

but they typically are not used for local operations. Individuals are assigned to each site. At the onset of an emergency 

situation, members monitor emergency channels to see what 

is going on and then make decisions on whether to operate 

the sites. The organization can also provide "shadows." 
A32 PERFORMANCE OF THE BUILT ENVIRONMENT 

Within minutes after the earthquake, the amateur-radio 

station at the Palo Alto City Hall EOC was staffed. A total of 

14 operators were on duty in the district. Others hams checked 

in but were not needed; some went to Los Gatos, Hollister, 

and Santa Cruz. The local repeater was particularly busy and 

became saturated at times, but without causing undue disruptions. Because telephone communications remained operational in the area, the ham emergency network was not 

called upon to provide the critical link that it did in other 

areas, although it did provide information on assessing the 

extent of earthquake damage, as well as providing communications to relocation centers. 

The ARES network played a much more important role 

in the harder hit areas, where telephone communications were 

not disrupted. In Hollister, the telephones in the EOC could 

not be used to communicate out of the local area, and the 

emergency power was a problematic. ARES had developed 

and made available to the EOC a communications van, as 

well as operators to run it. 

At the OES region 2 EOC, one to five ARES operators 

worked around the clock for 4 days. Radios were used primarily during peak hours when telephones would get saturated, a situation that lasted for about a week after the 

earthquake. 

Members of the Emergency Response Institute, a local 

hams group, met on January 13 and 14, 1990, to assess the 

earthquake performance of RACES and ARES; they made 

the following observations. There is a need for prearranged 

networks to operate on preassigned frequencies. The effects 

of the earthquake covered a larger area than had previous 

emergencies, and so there was a need for better coordination 

on a regional basis; communications at this level were difficult. The antenna drops at agencies that were to be supported could not be found. At some important sites, such as 

regional EOC7s, the concentration of public-safety radios and 

ham radios caused problems because fixed antennas were 

too close together. Although all sites were provided with 

operators, some areas became overworked. Agencies were 

unaware of the services that RACES and ARES could provide. Operators should come prepared, and their gear should 

have emergency power. EOC's should have permanent packet 

computer facilities with similar equipment and software with 

auto-printing, so that printing can run by itself, to make training manageable. More emergency repeaters are needed, 

which should be distributed at more sites for reliability; and 

portable units should be available to be put into service as 

need arises. Note that three repeaters were converted to emergency use: one to replace a failed unit, and two to increase 

capabilities. Two or three repeaters may have been purposely jammed. 

As a result of the earthquake, several organizations have 

become aware of the services that amateur-radio organizations can provide, and discussions are under way for establishing networks for utilities, departments of public works, 

and blood banks. For example, discussions are under way 

with PG&E to set up antenna drops at service centers to enable those locations to be contacted directly to report gas 

leaks and downed powerlines. Another example is Santa Clara 

County, which is installing packet systems at EOC7s in 15 

cities within the county. 

Another problem that OES communications staff noted 

is a tendency to use very high frequency (VHF) equipment, 

rather than high-frequency (HF) equipment. Although HF 

equipment is less mobile and requires a higher grade FCC 

license, it does have a much longer range and is independent 

of repeaters, which commonly are unreliable or become saturated in an emergency. The U.S. National Communications 

System has established the Shared Resources (SHARES) HF 

radio program for use by Federal agencies across the Nation. In 1993, nearly 1,000 SHARES HF radio stations were 

in operation. 

CONCLUSIONS ON 

COMMUNICATION SYSTEMS 

TELEPHONES 

Telephone equipment performed well during the intense shaking in the epicentral area and the moderate shaking in most other areas. Most equipment problems were 

with emergency-power generators, although they had little effect on system performance. The congestion of the 

telephone system was especially severe until midnight on 

the day of the earthquake. The emergency-response community had difficulties using telephones during working 

hours for several days after the earthquake. In general, 

people had difficulty in getting a line to call 9 11 for emergency service. Fortunately, relatively few injuries and fires 

were reported. 

EMERGENCY-COMMUNICATION SYSTEMS 

Overall, emergency-communication systems performed 

well. This good performance is partly attributable to the 

moderate intensities of ground shaking in most high-population-density areas. The emergency-response community 

was not significantly overextended. In addition, many of the 

problems confronting regional EOC's were associated with 

an abundance of aid and supplies, rather than shortages. The 

major problem at emergency-communication centers and 

EOC's was congestion of the telephone system. Essentialservice lines generally had moderate to long delays in getting a dialtone, an unexpected situation that slowed 91 1 

service. Radio communications for dispatch worked well in 

most places, but power outages to repeaters degraded radiodispatch performance. Some PSAP7s had difficulty in contacting utilities and public-works crews. 
COMMUNICATION SYSTEMS A33 

EMERGENCY POWER 

Emergency power failed after the earthquake. Important equipment in several facilities was not provided with 

emergency power. At many critical facilities, emergency 

power was unreliable. 

AMATEUR RADIO 

Amateur-radio emergency-communication groups 

played an important role during the earthquake. These groups 

were particularly helpful to EOC's when telephone lines became saturated; they also fulfilled their usual role of support 

for the American Red Cross and various shelters. However, 

several organizations that could have used amateur-radio 

services were unaware that they were available. 

RECOMMENDATIONS FOR 

COMMUNICATION SYSTEMS 

The following recommendations are provided as a basis for discussion, because many of the issues are quite complex and implementation must be well thought out. 

ALL COMMUNICATION SYSTEMS 

EMERGENCY POWER 

Improvements are needed in the reliability of emergency power. Those who install engine-generator sets, the batteries needed to start them, and their fuel supplies must 

consider earthquake loads in their designs (see Schiff, this 

chapter). Individuals who may be called upon to start the 

units, if they do not start automatically, and to keep them 

running should be given appropriate training. Improvements 

in the reliability of commercial power would reduce the need 

for emergency power. To improve power-system restoration, 

the Telecommunication Electric Service Priority (TESP) program is available from the U.S. Department of Energy and 

the National Communications System to rapidly restore power to critical telephone-company facilities. 

PUBLIC COMMUNICATIONS 

and the 1989 Loma Prieta, Calif., earthquakes, even though 

telephone systems were not significantly damaged and emergency-response needs were not fully taxed. In an earthquake 

that severely affects high-population-density areas, telephone-system congestion presents a significant safety problem. In the 1989 earthquake, public-service announcements 

requesting that telephones be used only for emergencies were 

frequently aired on the radio and television, but they did not 

prevent congestion. The personal need for individuals to know 

whether family or friends were safe typically was more compelling than admonitions to limit telephone use to emergency calls. Alternative strategies should be considered for 

controlling nonemergency calls. Initially, requests that usage be limited to emergency calls are appropriate; but after 

the initial crisis, perhaps people should be asked to make 

personal calls at off hours and keep them brief. 

A second approach is to establish a procedure for the 

appropriate agency, probably the OES in California, in which 

the appropriate authority (the governor) would declare a communications emergency. This declaration would apply to selected area codes in the affected area but would carry no 

penalties; it would simply involve airing public-service messages announcing that a communications emergency has been 

declared and that calls to and within the selected area codes 

are to be limited to emergency use only. Clearly, an extensive public-education program would be required before this 

system could be used, to avoid causing undue alarm when it 

is used. If such a program had been established, the 1989 

earthquake probably would not have warranted its use. 

A third approach is for State and local officials to utilize 

the Government Emergency Telecommunication Service 

(GETS), a Federally sponsored service available through the 

National Communications System, that gives priority on the 

public switched network to official emergency responders. 

911 SYSTEM 

The public needs more information on the use of the 

91 1 system in an earthquake. Public-service messages 

throughout the year should indicate that in a major disaster 

there may be a 2- or 3-minute delay in getting a dialtone but 

that, with patience, calls can be made. If 91 1 is busy, callers 

can use the seven-digit numbers listed in the telephone book 

for the desired agency. Finally, pay telephones should provide quicker access to a dialtone than other telephones. Recommendations for the redesign and improvement of the 

performance of the 9 11 system were presented by the Federal Communication Commission (1993). 

TELEPHONE-SYSTEM CONGESTION 

PBX SYSTEMS 

New approaches are needed for mitigating telephonesystem congestion. Significant congestion of telephone systems was reported after the 1987 Whittier Narrows, Calif., 

Organizations that use a PBX and need their telephones 

after an earthquake should consider earthquake performance 
A34 PERFORMANCE OF THE BUILT ENVIRONMENT 

more carefully. PBX units should be anchored and protected 

from falling objects. Emergency power should also be provided. 

CRITICAL FACILITIES 

ESSENTIAL-SERVICE LINES 

The performance of essential-service lines, which was 

poor in this earthquake, needs evaluation and improvement. 

Dialtone delays longer than 1 minute were reported for essential-service lines, delaying the transfer of calls at PSAP's 

and greatly increasing their response time. 

Essential-service lines should be available to all communities, and the service implied by having such a line should 

be well defined. Essential-service lines are not now available 

in all communities; for example, they are not offered in Gilroy or Morgan Hill, whereas in Los Gatos they are available, 

but calls on essential-service lines have to compete for access to trunks like any other call once the central office is 

contacted. If calls must be transferred at a PSAP, dialtone 

delay effectively makes the line unusable. At a minimum, 

emergency responders must know what to expect from their 

essential-service lines. 

SEISMIC DESIGN OF 

COMMUNICATION CENTERS 

The seismic-design criteria for important communication 

centers should be reevaluated. New technologies, such as optical fiber and digital-switching equipment, make the concentration of communication resources inevitable. The increasing 

importance of these facilities mandates such a reevaluation. 

EOC COMMUNICATION EQUIPMENT 

EOC communication equipment should be upgraded to 

take advantage of computers. Personal-computer systems 

have hardware and software that allow packet technology to 

be used over radio networks. Such packets systems should 

be integrated into the EOC's communication system. Computers would be able to transfer messages faster, provide hardcopy at both ends, and log all communications. They would 

also help provide discipline in message format, to ensure 

that the date, sender name and title, and recipient name and 

title are included. Such features as electronic bulletin boards 

could also be incorporated. As an example, the National Communication System has piloted a World-Wide Web (WWW) 

server called ERLink in which users can post information 

from their desktop or laptop computer to the WWW server, 

allowing the emergency-management community to share 

information quickly. 

ARES AND RACES 

The utility of ARES and RACES to EOC's should be 

enhanced. The value of ARES and RACES to EOC operations was amply demonstrated in the earthquake, which was 

only moderately damaging. More damaging earthquakes will 

increase the need for reliable long-distance communications, 

particularly between county and regional EOC's. One method for establishing communications between these EOC's 

would be the creation of an HF radio network, which could 

be done at low cost if antennas were installed at EOC's. Many 

ARES members have the licenses and equipment to establish radio-frequency (RF) networks, and they could do so if 

the antennas, which are not portable, were available. Within 

California, no central authority exists which can mandate 

that antennas be installed. Designated funding by an appropriate agency, such as the Federal Emergency Management 

Agency, may provide the incentive to add this resource to 

EOC's. In addition, cooperation with the Federal HF radio 

SHARES program should be encouraged. 

EOC ANTENNAS 

Antennas associated with EOC's should be evaluated. 

The many radios that were assembled at one EOC caused 

problems because the antennas were too closely spaced. Antennas should be evaluated for this deficiency and corrected. 

REPEATERS 

Repeaters used for emergency services, such as ARES, 

should have generator-based backup power to ensure their operation for extended periods. Although many repeater sites have 

this capability, it has a significant cost. Because these emergency repeaters provide a critical service to the emergency-response 

community, a means should be established for members of the 

emergency-response community, such as the OES, to bear the 

cost of emergency power. 

CRITICAL RADIO EQUIPMENT 

Installation standards are needed for critical radio equipment. This equipment should be installed using highly conservative criteria, particularly when it will be located on peaks 

or ridges. Ground motions can be greatly amplified on peaks, 

and so accelerations may be unusually high. Because of the 

inaccessibility of these sites and frequent damage to access 

roads, equipment reliability is of special concern. Finally, if 

any item of critical equipment is located in a room, all the 

equipment should be installed with the same high standard 

because nonessential equipment may fall over and damage 

essential equipment. Repeaters used by hams for emergency 
COMMUNICATION SYSTEMS A35 

operations should be installed using these same high standards. Implementation of such standards would be difficult 

because no governmental or trade organization of antennasite operators exist. Two steps to initiate improved practices 

would be (1) to establish seismic-resistance guidelines for 

the installation of communication equipment and (2) to establish model lease agreements that site operators could use 

and that government agencies could require. Most good, seismically resistant installations already require that equipment 

be anchored, a relatively inexpensive task. 

PSAP POWER NEEDS 

The power needs of PSAP's should be evaluated. The 

use of small, unintermptable power supplies should be considered for operator-position consoles, lights, and computeraided dispatch. With these power supplies, short interruptions 

of power from engine generators would not disrupt PSAP 

operations. 

CELLULAR TELEPHONES 

Cellular telephones provide an alternative communication method. They can avoid the congestion associated with 

common-carrier switched networks. However, overuse of the 

cellular-telephone network can also lead to congestion. Adoption and implementation of the National Communications 

System-initiated CPAS program should be encouraged. 

CENTREX SYSTEM 

Critical facilities that need internal telephone communications during an emergency-response period should evaluate the appropriateness of using the Centrex system. This 

system has one drawback: If a central-office switch becomes 

saturated, telephone communications within the critical facility may be significantly degraded. 

AMATEUR-RADIO EMERGENCY SERVICES 

EMERGENCY-RESPONSE MANUALS 

Hams should have emergency-response manuals that list 

the sites that hams support, identify the locations of antenna 

drops, provide the names of contacts at these sites, and identify various amateur-radio networks and their frequencies. 

ARES RESOURCES 

ARES should evaluate whether it is overextending its 

resources. ARES is currently planning to expand into other 

areas where its services are needed, such as utilities, public 

works, and blood-bank networks. In the earthquake, however, there was a shortage of operators to fill needed slots at 

some locations. Future earthquakes of similar magnitude or 

larger that occur closer to large urban areas will greatly expand the number of sites that must be serviced, and so the 

emergency can be expected to last longer. One problem in the 

1989 Loma Prieta earthquake may have been that ARES was 

underutilized to the point that some operators lost interest. 

REFERENCE CITED 

Federal Communication Commission, 1993, Network reliability: 

a report to the nations: Chicago, National Engineering Consortium. 

A38 PERFORMANCE OF THE BUILT ENVIRONMENT 

From April 1989 through February 1990, OMNCS sponsored a task performed by MITRE Corp. to develop and apply a prototype model for accomplishing these objectives. 

Initially, the model was to be developed and applied to a set 

of postulated scenarios for the New Madrid, Mo., seismic 

zone, which affects seven of the Central United States. Before this prototyping effort was completed, the 1989 Loma 

Prieta earthquake occurred in California. Subsequently, 

MITRE Corp. was requested to validate the prototype model 

against the actual building damage and NSIEP telecommunication-service disruptions that occurred. This model-validation effort was carried out from August 1990 through June 

199 1 ; the results, conclusions, and recommendations are reported in this paper. 

MODEL-VALIDATION METHODOLOGY 

In general terms, the model-validation methodology consisted of the following steps: (1) use the 1989 Loma Prieta 

earthquake as a test case for validating the model; (2) compare the model's projected building damage and NSIEP telecommunication-service disruption with the observed effects 

of the earthquake; (3) on the basis of a comparison using statistical tests, validate the model; and (4) report the conclusions to OMNCS. 

To implement this approach, a definition of model validity was needed, followed by a specification of the statistical tests required to measure it. Because validating a model is 

similar to testing a scientific theory, a definition of model 

validity can be adapted from the philosophy-of-science literature: "To accept that a model is valid is to be convinced 

that what a model predicts about what is observable is true" 

(paraphrased from van Fraassen, 1980). More specifically, a 

model is valid if its predictions consistently agree with observation, and a model is invalid if its predictions disagree 

with observation. Note, however, that a single experiment, 

such as the natural experiment provided by the 1989 Loma 

Prieta earthquake, cannot totally validate a model although it 

can support its validity. 

To make the transition from this general definition of 

validity to specific statistical tests, we must first introduce 

some more specific model-validation concepts. For the purposes of this work, three such concepts are: (1) site-by-site 

validity-the model makes a high percentage (say, 70 percent or greater) of correct predictions of damage or disruption on a site-by-site basis; (2) proportion validity-the model 

correctly predicts the overall proportion or pattern of damage 

or disruption as measured by several statistical tests; and (3) 

absolute sample validity-the model is found to possess both 

site-by-site validity and proportion validity. This third concept is the one desired to hold as a result of any model-validation process. We can never conclude, however, that a model 

is unqualifiably "absolutely" or "completely" valid, no matter how many tests we carry out, although strong support for 

its validity would be provided by a testing process that showed 

it to have an absolute sample validity for every sample tested 

in every earthquake. 

Now, we are ready to specify the statistical measures to 

be used in applying these model-validation concepts. Siteby-site validity is implemented through three percentage 

measures: (1) a high percentage (say, 70 percent or greater) 

of the model's predicted damage or disruption must agree 

with the observed damage or disruption, (2) a high percentage of the model's predictions of no damage or no disruption 

must agree with the observations of no damage or no dismption, and (3) a high percentage of the model's overall predicted results of damage or disruption must agree with the 

overall results of observed damage or disruption. 

Similarly, proportion validity is implemented by several 

statistical measures. (1) Same proportion is the statistical test 

of comparing the proportions in paired binomial samples; here, 

the samples consist of the predicted and observed proportions of damagelno damage or disruptionlno disruption. A 

successful result is the inability to reject the null hypothesis 

of no difference between the sample proportions at the 95- 

percent-confidence level. (2) Probability ofproportions is the 

nonparametric analog (known as Fisher's exact test) of the 

same-proportion test. This statistical measure yields the probability of obtaining the proportions found in each sample under 

the null hypothesis of no difference in the proportions of the 

underlying populations (equivalent to the assumption that the 

model perfectly replicates reality). (3) Significant positive 

correlation is Pearson's correlation coefficient applied to the 

correlation between predicted and observed results. A positive correlation that is significantly different from 0 at the 95- 

percent-confidence level represents a successful test on this 

statistical measure. 

To satisfy both site-by-site validity and proportion validity, the model's predictions must pass all three tests under 

each statistical measure. 

OBSERVED EARTHQUAKE EFFECTS 

Data were collected on the impact of the 1989 Loma 

Prieta earthquake on three types of facilities: NSIEP telecommunications-user office buildings, telecommunications 

central offices, and high-voltage (2301500 kV) power-transmission substations. The types of data collected were building damage, power outages, and PSN disruption; the data 

sources are listed in table 1. 

NSEP telecommunications users were interviewed by 

telephone, using a standardized survey questionnaire. Out of 

a total of 3 13 Government NSEP telecommunications users 

located in a 100-mi radius of the earthquake epicenter, 43 

were randomly selected to be interviewed. The only criterion 

applied in the selection process (other than the ability to make 

telephone contact and complete the questionnaire) was that 

there be a good geographic distribution throughout the areas 

A40 PERFORMANCE OF THE BUILT ENVIRONMENT 

EARTHQUAKE-MODEL METHODOLOGY 

Anecdotal evidence from past earthquakes suggests little 

correlation between building damage and telecommunication-service disruption; however, other anecdotal evidence 

suggests some correlation between power outages and telecommunication-service disruption. The proposed methodology establishes a statistical framework in which both of these 

hypotheses can be tested by using observed data on building 

damage, power outages, and telecommunication-service disruption. 

This section describes the methodology used to predict 

building damage and NSIEP telecommunication-service disruption. The predicted disruption was tested in two ways: with 

and without taking into account the effects of substation power 

outages. 

Before providing an overview of the modeling methodology, the OMNCS-established constraints on model selection must be mentioned. The first constraint was that for this 

prototype modeling effort, the models must be selected from 

the open literature. Thus, candidate models were identified 

through literature review, not through a Government solicitation or request-for-proposal process. Second, the models must 

not require too much building- or equipment-specific detail; 

that is, only such building- or equipment-specific detail as 

could be obtained through existing OMNCS data bases or 

through the brief NSEP telecommunications-user interviews 

and resource-constrained data-collection effort would be permitted. This second constraint eliminated from consideration 

most structural-engineering building-damage models. 

After a review of the literature, one of the few models 

that satisfied these constraints was the model of Thiel and 

Zsutty (1987a, b), researchers at the Earthquake Engineering 

Research Institute. Their model is a nonproprietary model 

with all of the variables and parameter values disclosed, but 

not so detailed as to make data collection infeasible. The model 

predicts the structural damage to a building as a function of 

four variables: (1) the building's seismic vulnerability (a range 

of about 60 discrete values), (2) the building-site resonancefrequency coupling, (3) the soil conditions at the building site, 

and (4) the randomly oriented peak ground acceleration. The 

product of these four variables, together with some curvefitting coefficients and exponents, constitutes the probability-of-damage parameter P, which, in turn, generates the 

probabilities for each of the five discrete damage states required to predict the damage to a given building (Thiel and 

Zsutty, 1987a). This model was applied to both NSEP telecommunications-user office buildings and central offices. The 

combined sample of 73 buildings (43 office buildings and 30 

central offices) was used as the basis for validating the building-damage submodel. 

The model of Thiel and Zsutty (1987a, b), however, could 

not be applied as straightforwardly as described above. Instead, their model had to be calibrated because of its discovered systematically low predictions in initial runs (pretesting). 

The calibration involved establishing a damage threshold at 

or above which a building (for example, a central office) would 

be considered nonfunctional and below which it would be 

considered functional. Because the correct damage threshold 

is unknown, several thresholds were tested: 10, 15, and 25 

percent. Application of these damage thresholds to the output of the building-damage submodel transformed that output from a value within the range 0-100 percent to a binary 

output of 0 or 1, representing no functional loss or functional 

loss, respectively. In short, the model was validated separately 

and completely at each of the calibrated damage thresholds. 

To determine the impact on NSEP telecommunications 

users, the following analytic principle was used: If one or 

more of the central offices in the homing chain serving an 

NSEP telecommunications user (that is, an end office, local 

tandem, or access tandem) were projected by the buildingdamage submodel to be nonfunctional, then the NSEP telecommunications user was projected to have lost local PSN 

service. A projection of this type was made for each of the 43 

NSEP telecommunications users interviewed. 

The above projection of telecommunication-service disruption does not take into account the possible impact of power 

outages on NSEP telecommunications users. A simplistic 

concept was applied to attempt to take such power outages 

into account: identify all of the major high voltage (2301500 

kV) power substations closest to each central office; if all of 

those substations (generally, two or three) reported earthquakeinduced power outages, then the central office was assumed 

to have lost its utility-supplied power. It was further assumed, 

under this simplistic approach, that if all the substations reported power outages, the total power-outage duration would 

be sufficiently long that the central office would have exhausted its battery-plus-emergency-generator backup power 

and go out of service. The key question was whether or not 

this simplistic approach to account for the impact of power 

outages would improve the validity of the model for projecting telecommunication-service disruptions. 

MODEL-VALIDATION RESULTS 

Model-validation tests were run with each of the three 

damage thresholds for the statistical measures of site-by-site 

validity and proportion validity. The test using power-outage 

effects was run only at the 15-percent-damage threshold because this level was determined to be the best for predicting 

telecommunication-service disruption. The results are summarized in tables 5 through 7. 

From the data listed in table 5, the lo-percent-damagethreshold model possesses site-by-site validity (assuming that 

a 70-percent-correct prediction is adequate) for NSEP telecommunications-user office buildings and central offices. No 

threshold model was found to possess proportion or absolute 

sample validity. 

From the data listed in table 6, the 15-percent-damagethreshold model possesses proportional validity for local tele- 
MODELING THE IMPACT OF THE EARTHQUAKE ON TELECOMMUNICATION SERVICES A4 1 

Table 5.-Model-validation results for public-switched-network 

central offices. 

[Sample size: 73. nla, not applicable] 

Model-validation 

concept Statistical test 

Damage threshold (percent) 

Site-by-site validity: 

Correct damagedl ------------------- 100 0 0 

Correct undamaged2 ---------------- 70 87 99 

Correct overal13 ...................... 73 81 92 

Result------------------------------------------------------------ Yes NO NO 

Proportion validity: 

Same proportion4 at the No Yes n/a 

95-percent-confidence 

level. 

Probability of proportions5 Low Moderate Low 

under the null hypothesis. (-0) (0.28) (0.1) 

Significant positive correlation6 Yes No No 

at the 95-nercent-confidence 

'Predicted percentage of correct damaged. 

Predicted percentage of correct undamaged. 

Predicted percentages of total correct (damaged plus undamaged). 

"Paired binomial samples: proportion of success for the null-hypothesis test (rejected 

at the 95-percent-confidence level). 

Wisher's exact test (nonparametric): probability of getting sample proportions under 

the null hypothesis. 

6Pearson's correlation coefficient. 

Table 6.-Model-validation results for local telecommunication services. 

[Sample size: 431 

Model-validation Damage threshold (percent) 

concept Statistical test 

10 15 25 

Proportion validity: 

Same proportion4 at the No 

95-percent-confidence 

level. 

Probability of proportions5 Low 

under the null hypothesis. 

Significant positive correlation6 (2: at the 95-percent-confidence 

level. 

Result ............................................................ No 

33 

94 

81 

No 

Yes 

Moderate 

(0.19) 

Yes 

Yes 

0 

100 

79 

No 

No 

Low 

(-0) 

No 

No 

'Predicted percentage of correct service disrupted. 

Mediated percentage of correct service not disrupted. 

Predicted percentages of total correct (damaged plus undamaged). 

"Paired binomial samples: proportion of success for the null-hypothesis test (rejected at the 95-percent-confidence level). 

Wisher's exact test (nonparametric): probability of getting sample proportions under 

the null hypothesis. 

^Pearson's correlation coefficient. 

communication services without accounting for power-outage effects. No threshold model was found to possess siteby-site or absolute sample validity. 

From the data listed in table 7, slightly improved numerical results were obtained by including power-outage effects; however, the pattern of results does not differ qualitatively 

from that in table 6. 

Table 7.-Model-validation results at the 15-percent-damage threshold for local telecommunication services that reported power outages. 

[Sample size: 431 

Model-validation 

concept Statistical test Result 

Site-by-site validity: 

Correct service disrupted'---------- 44 

Correct service not disrupted2 ----- 94 

Correct overal13 ...................... 84 

Overall result ................................................... No 

Proportion validity: 

Same proportion4 at the Yes 

95-percent-confidence 

level. 

Probability of proportions5 Moderate 

under the null hypothesis. (-0) 

Significant positive correlation6 Yes 

at the 95-percent-confidence 

level. 

Overall result ................................................... Yes 

Predicted percentage of correct service disrupted. 

Predicted percentage of correct service not disrupted. 

Predicted percentages of total correct (damaged plus undamaged). 

Paired binomial samples: proportion of success for the null-hypothesis test (rejected at the 95-percent-confidence level). Â¥"Fisher' exact test (nonparametric): probability of getting sample 

proportions under the null hypothesis. 

^Pearson's correlation coefficient. 

CONCLUSIONS AND 

RECOMMENDATIONS 

CONCLUSIONS 

Neither the building-damage submodel nor the telecommunications-impact submodel was found to be (absolute 

sample) valid for the 1989 Loma Prieta earthquake. 

The building-damage submodel, without imposing thresholds, underpredicts the observed damage levels. 

The building-damage submodel, at the lo-percent-damage threshold, might be used on an interim basis for the 

Loma Prieta region to predict site-by-site damage (for example, for the OMNCS' National Level Program supporting analysis). 

The telecommunications-impact submodel, at the 15-percent-damage threshold, with or without power-outage effects, might be used with caution, on an interim basis, for 

the Lorna Prieta region to predict the proportion of telecommunication-service disruption (for example, for realtime emergency response). 

RECOMMENDATIONS 

A single model for the Loma Prieta region and other California earthquake-prone areas needs to be developed that 
A42 PERFORMANCE OF THE BUILT ENVIRONMENT 

is valid for predicting both building damage and telecommunication-service disruptions. 

Models need to be developed and validated for other earthquake-prone areas of the United States. 

The U.S. National Science Foundation and the National 

Communications System should continue to sponsor further research on telecommunications impacts, as well as 

power-outage effects. 

OMNCS should phase in validated models on a region-byregion basis for the purposes of supporting analysis for the 

U.S. National Communications System's National Level 

Program and for real-time emergency response. 

ACKNOWLEDGMENTS 

This research was supported by the Office of the Manager, U.S. National Communications System under contract 

F 19628-89-C-000 1, program element 3 127K, task order 

3 1 10. Public release of the research was authorized in March 

1992 by Dennis I. Parsons, Assistant Manager, U.S. National 

Communications System. The work was carried out at 

MITRE Corp.'s Washington C3 Center in McLean, Va. 

REFERENCES CITED 

MITRE Corp., 199 1, Earthquake model validation; final results: 

McLean, Va., briefing prepared for Office of the Manager, U.S. 

National Communications System. 

Thiel, C.C., Jr., and Zsutty, T.C., 1987a, Earthquake characteristics 

and damage statistics: Earthquake Spectra, v. 3, no. 4, p. 747- 

792. 

1987b, Earthquake parameters and damage statistics: San 

Francisco, technical report prepared for Forell/Elsesser Engineers. 

van Fraassen, Bas, 1980, The scientific image: Oxford, U.K., Oxford University Press. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

THE MEDIA: RADIO, TELEVISION, AND NEWSPAPERS 

CONTENTS 

By Richard J. Rapaport, Freelance Writer 

ABSTRACT 

The media organizations in the San Francisco Bay region that had planned for a major disaster (that is, had emergency-preparedness plans and emergency-power generators) 

performed well in the earthquake. Many media organizations, 

however, were poorly prepared, and senior management commonly was unaware of the inadequacy of their emergency 

planning, particularly with regard to the absence of emergency-power generators. 

The key problem for all media was the loss of commercial 

power and the inadequacy or absence of emergency-power-generating capacity. Partial loss of telephone communications, loss 

of broadcast towers, and difficulty in accessing the more severely earthquake-affected areas by ground transportation also 

impaired coverage. The response of the electronic media was 

probably enhanced by the presence in San Francisco of additional staff and equipment to cover the 1989 World Series, 

which was scheduled to begin minutes after the earthquake 

occurred. 

Individual television- and radio-station performance varied; five radio stations were able to broadcast during the first 

few hours after the earthquake. The designated Emergency 

Broadcasting System (EBS) station (KNBR-AM) was one 

of the first radio stations back on the air, but because its staff 

was isolated at the ballpark, it failed to provide useful information beyond the standard EBS alert. 

Loss of commercial power, which was also a key problem for the three major newspapers in the area and had the 

greatest impact during the first 36 hours after the earthquake. 

The San Jose Mercury-News, the newspaper closest to the 

epicenter, was able to restore full power to all its facilities 

within an hour from its emergency-power generators; and it 

produced its normal morning edition, including 100,000 extra copies and an earthquake supplement. The San Francisco 

dailies, the Chronicle and Examiner, neither of which had 

emergency-power generators, relied on emergently procured 

small generators and Macintosh computers to compose abbreviated editions but were unable to print until commercial 

power was restored to the printing plant the morning after 

the earthquake. They also relied on a special temporary feed 

from the Pacific Gas and Electric Co. (PG&E) to provided 

full power to their main office on the night after the earthquake. The distribution of newspapers was not significantly 

impaired by damage to the transportation system, although 

delivery to homes and news racks was spotty. 

PUBLIC MEDIA 

The 1989 Loma Prieta earthquake tested northern California's media in an unprecedented way. The last temblor of 

comparable consequence, in 1906, happened long before the 

advent of television, at a time when radio was barely out of 

Marconi's laboratories. Indeed, the only San Francisco Bay 

region medium that covered the 1906 earthquake was the 

newspapers, and in 1989 the events of more than 80 years 

ago were so remote that little or no collective memory remained on how to deal with a disaster of such magnitude. 

Radio, television, and newspapers were forced to rely 

on emergency plans, when any plans existed at all. After the 

1989 Loma Prieta earthquake, the key problems for all the 

media generally involved the loss of commercial power and 

a lack of emergency-power-generating capacity. To a lesser 

extent, they also had a transportation problem, which made 

coverage difficult when electrical power was restored. This 

problem contributed to the limited coverage in the epicentral area, causing most of the world to believe that San Francisco was the hardest hit area, rather than Santa Cruz and its 

surroundings. 

There was a critical disparity in reports of the number 

of dead from the earthquake, largely because of the changing statements of the Alameda County Sheriff, who later admitted to "shooting from the hip" about the number of deaths 

on the Cypress Avenue viaduct. The highest death toll reported was 270. 

One factor that skewed coverage of the earthquake also 

made it as pervasive and comprehensive as it was: The San 

Francisco Bay region media, and large components of the 
A44 PERFORMANCE OF THE BUILT ENVIRONMENT 

national media, were in place and geared up for northern 

California's most important media event in years, the 1989 

World Series. 

From a media point of view, the earthquake's timing 

was uncanny. Moments before the third game of a World 

Series matchup between the two San Francisco Bay region 

teams, the earthquake rumbled through. With much of the 

country already tuned in, the earthquake gave radio, television, and, to a lesser extent, newspapers a great opportunity 

to display their news gathering and disseminating abilities 

under fire. Coverage ran the gamut from the extraordinary to 

the abysmal. 

RADIO 

One of the first stations to get back on the air after the 

earthquake was KNBR-AM, the designated Emergency 

Broadcasting Station (EBS) for the San Francisco Bay region. As planned, KNBR's EBS alert cut in, but when the 

alert ended, the station returned to local coverage of the 1989 

World Series from Candlestick Park. 

No extensive damage at Candlestick Park was reported, 

and officials, fans, and sports media were not even sure 

whether the game would be canceled. The KNBR announcer 

told listeners that there would be a slight earthquake delay 

before getting to the starting lineups. On another station providing World Series coverage, the announcer got out the San 

Francisco telephone book and began reading the earthquakeemergency section in the front. 

KG07s AM studio, built on landfill near Embarcadero 

One in downtown San Francisco, was hard hit. Wire copy, 

books, and nearly all other objects fell to the floor, and two 

of their three broadcast towers were knocked down. KG0 

was off the air for about 40 minutes. Because it has a large 

news staff and was able to utilize the resources of KGO-TV 

and the ABC network, KGO-AM provided some of the best 

radio coverage in the days after the earthquake. It covered 

the story about the devastation around Santa Cruz, Los Gatos, 

and Watsonville, which was largely missed by less news oriented radio stations and by television, a medium dependent 

on highly technical equipment and satellite and microwave 

relays. 

Ultimately, many radio listeners turned to KCBS-AM, 

probably because it is the only all-news station in the San 

Francisco Bay region. When the earthquake hit, KCBS was 

30 seconds away from the end of the national news feed and 

2% minutes away from switching to live network coverage 

of the World Series. The station had dozens of reporters all 

around the San Francisco Bay region, an anchor booth at 

Candlestick Park, and another portable studio outside the 

park. The earthquake knocked out both the electrical power 

and most of the telephones at KCBS7 offices in downtown 

San Francisco, but a rooftop emergency-power generator 

kicked in almost immediately, and the station came back on 

the air after only a few seconds. With the telephones to 

Candlestick Park out, the KCBS announcer could broadcast 

but did not know whether anyone was picking him up; and 

like many people at Candlestick Park, he did not know how 

severe the earthquake really was. 

With official information slow to arrive, KCBS staff 

began to take calls from listeners, hoping to pinpoint the epicenter and assess the damage. Reporters, both on duty and 

off, also began to check in. Piece by piece, an accurate picture of the earthquake began to emerge. 

About 6:15 p.m., the KCBS emergency-power generator failed, but engineers were able to tap into another generator, which gave the station a few lights in the broadcast 

studio and the ability to stay on the air. For the rest of the 

night, however, gallons of kerosene had to be hauled up 30 

flights of stairs-the elevators were out-to keep the generator going. 

Five radio stations in the region used flashlights, emergency-power generators, and a degree of telephone service 

to keep the San Francisco Bay region informed, reassured, 

and connected during the first dark hours after the earthquake. 

Telephone calls from listeners and from professional reporters provided a dramatic and informative picture of a region 

in an emergency. 

The largely improvised coverage, particularly at KCBS 

and KGO, went as smoothly as if it had been planned for 

years. Both stations abandoned their normal commercial formats for the rest of the first week after the earthquake, acting 

as information clearinghouses as the extent of the transportation, communication, and property damage became apparent. Large parts of the Nation were able to share in the 

dramatic radio coverage, which was so compelling that affiliated stations in New York, Chicago, Los Angeles, and elsewhere tapped into the satellite uplinks carrying KG0 and 

KCBS and carried them live until the following morning. 

Several days later, the New York Daily News quoted the 

manager of New York7s WCBS-AM as saying, "[KCBS] had 

a large number of reporters on the scene immediately and were 

way ahead of reporters from UP1 and other news services.', 

TELEVISION 

Because television is quite pervasive and yet has a limited focus, its coverage ultimately may have done as much 

harm nationally and internationally as it did good regionally. The sight of network news anchors standing in front of 

the same burned and broken Marina District block or at the 

collapsed freeway in Oakland left an impression of absolute 

destruction in a measure equal to that of the 1906 earthquake 

and fire. 

KG0 was out in front from the start. Network sports 

commentator A1 Michaels was able to provide several minutes of live audio color commentary before ABC7s power 

went down entirely. ABC exploited its use of the Goodyear 
THE MEDIA: RADIO, TELEVISION, AND NEWSPAPERS A45 

blimp, which was circling Candlestick Park and veered off 

to take the first shots of the downed span in the San Francisco-Oakland Bay Bridge. 

Surprisingly good coverage also came from the San 

Francisco independent station KOFY, which provided half a 

dozen of its employees with minicams. These amateurs managed to bring back some of the rawest, yet most powerful, 

visual images of the earthquake. 

One of the most striking video shots, which was aired 

repeatedly, was taken by tourists who happened to be caught 

near the collapsed span of the San Francisco-Oakland Bay 

Bridge with their own camera. The video showed a car plunging over the edge of the open span and striking the inclined 

collapsed span. The tourists sold their videotape to all three 

of San Francisco's major commercial stations within hours. 

KRON, the local NBC station, which had been making 

huge strides in providing the San Francisco Bay region with 

serious and measured news coverage, was caught with its 

power down and its anchor out of town. Because KRON did 

not own an emergency-power generator, it went off the air as 

soon as the earthquake hit. Either because of the power outage or, as was later claimed, because of the failure of an NBC 

network employee to set a switch, KRON was unable to feed 

its earthquake footage to the network. NBC viewers across 

the nation thus remained unaware of the damage for hours. 

NEWSPAPERS 

The morning San Francisco Chronicle did not appear 

on Wednesday, October 18, until early afternoon. At that time, 

the paper put out an eight-page "Earthquake Extra" that had 

been put together by flashlight on Macintosh computers. 

That same afternoon, the San Francisco Examiner managed to outdo its partner newspaper by a mere eight pages. 

Neither paper was able to include ads or classified sections. 

In contrast, the San Jose Mercury-News was able to put 

out its normal edition the next morning, as well as a 12-page 

color wraparound about the earthquake. They printed more 

than 100,000 extra copies of the newspaper, thousands of 

which were distributed in news-hungry San Francisco. 

The Mercury-News was no less damaged in the earthquake than the Chronicle/Examiner; San Jose was actually 

closer to the epicenter than San Francisco. Nor did the Mercury-News avoid the power outage that dogged the San Francisco papers. What distinguished the Mercury-News' response 

was simply that it had planned for a major crisis, whereas 

the Chronicle/Examiner had not. 

When the earthquake hit, power at the Mercury-News 

went down for an hour because a switch to the massive emergency-power generators malfunctioned; but when the switch 

was repaired, full power was restored to the newsroom and 

the presses. By 6:00 p.m., the Mercury-News was functioning fully. Photographs and text of a 12-page color World Series supplement were quickly changed and the Mercury-News 

was ready to print a color earthquake supplement for the next 

morning. 

At the Chronicle, however, the story was entirely different. Top Chronicle management sent a worker to the roof 

to start their emergency-power generator; they were surprised 

to find that there was no emergency-power generator. What 

senior management of the Chronicle and Examiner had imagined was a generator was actually a series of batteries designed to accommodate the orderly shutdown of computers 

in case of an emergency. 

Even though the Chronicle had an agreement with the 

Mercury-News that would allow each to use the other's newsroom and print facilities in case of a strike or emergency, the 

Chronicle did not use the San Jose paper's facilities. Instead, 

they managed to procure several small gasoline generators, 

and the staff began the task of producing a skeleton version 

of the newspaper with several Macintosh computers, a laser 

printer, a Xerox machine, and an old Royal manual typewriter. 

Throughout the night of Tuesday, October 17, reporters 

and editors were led up the darkened stairs of the Chronicle's 

Fifth and Mission Streets headquarters to the third-floor conference room. There, the entire editorial staff huddled around 

a huge table, editors reading and correcting copy while lowerranking employees stood behind them with flashlights. By 

early morning, the "Earthquake Extra" had been composed. 

The Examiner staff, using their own Macintosh computers, several cellular telephones, and a small generator, produced a 16-page edition. When electrical power was restored 

to the San Francisco Newspaper Agency's Army Street printing plant by early the next morning, both the Chronicle and 

Examiner were finally able to get out their newspapers. 

The lateness of delivery and the hunger for news about 

the earthquake had created an almost-insatiable demand for 

newspapers. One enterprising Examiner driver managed to 

sell 7,500 papers from the back of his truck, but this meant 

that many news racks remained empty. Home delivery of 

both the Chronicle and Examiner was spotty. Both the Mercury-News and the Sacramento Bee capitalized on the shortcomings of the San Francisco dailies, selling or giving away 

tens of thousands of papers that they had trucked in. 

The next night, things were easier for the San Francisco 

dailies. Electrical power was still out at the Fifth and Mission Streets headquarters, but PG&E managed to rig an electrical conduit (which required that electrical power be cut off to 

the San Francisco Hall of Justice and Jail for several hours) that 

allowed printing of expanded, if not preearthquake-length, 

newspapers. 

Although the San Francisco Chronicle and Examiner 

were unable to agree on an emergency-power-generator-sharing arrangement, in general, an unprecedented degree of cooperation prevailed between the less affected suburban 

newspapers and the crippled inner-city newspapers. In addition to the Mercury-News, both the Marin Independent Journal and the Oakland Tribune offered assistance, and the 
A46 PERFORMANCE OF THE BUILT ENVIRONMENT 

Examiner actually availed itself of the Independent Journal's just to get an edition out, several suburban dailies, including 

photographic laboratories. the San Jose Mercury-News, the Marin Independent JourIn general, the suburban newspapers seemed to have nal, the Contra Costa Times, and the Daily Review were able 

fared better than the city newspapers. On the day after the to put out special color sections with a vast array of informaearthquake, while the San Francisco dailies were struggling tion about the earthquake. 

A48 PERFORMANCE OF THE BUILT ENVIRONMENT 

Aqueduct of the State Water Project, pumped from local 

ground-water basins and collected as local surface water from 

streams and springs. The wastewater-treatment facilities discharge treated water into San Francisco Bay, the Pacific Ocean, 

Monterey Bay, and sewage lagoons. 

GEOGRAPHIC AREAS 

The agencies investigated and their locations are shown 

in figure 1. The earthquake-affected area is subdivided into 

four geographic areas: (1) central San Francisco Bay: San 

Francisco, Alameda, and Contra Costa Counties, including 

the cities of San Francisco, Oakland, Alameda, Berkeley, and 

other cities; (2) south San Francisco Bay: Santa Clara and 

San Mateo Counties, including the cities of Palo Alto, San 

Jose, and Los Gatos and surrounding area; (3) Monterey Bay: 

Monterey and San Benito Counties, including the cities of 

Hollister and Watsonville; and (4) Santa Cruz: Santa Cruz 

County, including the cities of Soquel, Santa Cruz, Aptos, 

and Scotts Valley, the San Lorenzo Valley, and the Santa Cruz 

Mountains and surrounding area. 

SEWER 

10. CITY OF Scows VALLEY-SEWER 

9 Sacramento 11. CITY OF SANTA CRUZ-SEWER 

13. SANTA CRUZ COUNTY 

SANITATION DISTRICT 

16. CITY OP WATCONVILLE-SEWER 

Tracy 2L CITY W HOLLJOTERÃ‘SEWE 

22. SUNNY SLOPE COUNTY WATER 

DISTMCTCEWER 

26. ~TY OF SAN JOSBÃ‘SEWE 

27. UNION SANITARY DISTRICT 

29. CITY OF PALO 

ALTOÃ‘REGIONA 

WASTEWATER 

30. SOUTH BAYSIDE SYSTEM 

AUfHOKrTY-REGION AL 

W ASTRW ATE13 

$1. SAN MATEDÃ‘SEWE 

(INDIRECT) 

34. CITY 0VSAN 

FRANCISCO-CLEAN 

WATERPROGRAM 

36. EAST BAY MUNICIPAL 

WATER 

1. REDWOOD ESTATES 

MUTUAL WATER COW 

2. ALDERCROFT VALLEY 

WATER COMPANY 

3. IDYLWILD WATER 

COMPANY 

4 CHEMEKTA PARK WATER 

COMPANY 

5. MOUNTAIN CHARLIE 

WATERWORKS INC. 

6. VILLA DEL MONTH MUTUAL WATER 

COMPANY 

7. KtVA RIDGE MUTUAL WATER 

COMPANY 

8. Â§A LOREN20 VALLEY WATER 

DISTRICT 23. SANTA CLARA VALLEY WA'CHR DISTRICT 

9. SCOTTS VALLEY WATER DISTRICT 24. SAN JOSE WATER COMPANY 

12. CITY OF SANTA CRIUZ-WATER 25. CALIFORNIA WATER SERVICE COMPANY 

14. SOQUEL CREEK WATER WATER 28. PURISSIMA I DLLS WATER DISTRICT' 

DISTRICT 32. CITY OF SAN VRAN~SCOÃ‘Crr WATER 

15. CITY OF WATSOlWILT4H-WATER 33. CITY OF SAM FRANCISCOÃ‘PUBLI WORKS 

17. PAJARO COMMUNITY SERVICES MECHANICAL (AWSS) 

DISTRICT 35. EAST BAY MUNICIPAL UTILITY DISTRICT-WATER 

18. SUNNY MHSA WATER DISTRICT 37. ALAMEDA COUNTY WATER DISTRICT 

19. CTSY OF HOLLISTER-WATHR 38. CITY OF TRACY-WATKR 

20. SUNNY SLOPE COUNTY WATER DISTRICT 39. SACRAMENTOÃ‘SEWE (INDIRECT) 

Figure 1 .-San Francisco Bay region, showing locations of water and sewage agencies surveyed. 
WATER AND WASTEWATER SYSTEMS A49 

WATER SYSTEMS 

CENTRAL SAN FRANCISCO BAY AREA 

In the central San Francisco Bay area, no damage to the 

Mokelumne, Hetch Hetchy, South Bay, or California Aqueducts or to any of the aqueduct storage reservoirs was reported. The Hetch Hetchy Aqueduct supplies wholesale water 

to 32 water purveyors on the San Francisco peninsula and in 

the south San Francisco Bay area (80-85 percent of aqueduct 

total). The reported damage to retail water purveyors in the 

peninsula and south San Francisco Bay area served by the 

Hetch Hetchy Aqueduct was minimal. 

EARTHQUAKE DAMAGE AND RESTORATION 

Approximately 350 water-main repairs were reported in 

the central San Francisco Bay area, primarily in the older, 

unstable areas the along the bayshore in Oakland, Berkeley, 

and Alameda (fig. 2), and in San Francisco in the infirm (unstable) areas of the Marina District and South of Market area 

and along the bayfront. The longitudinal and circumferential 

breaks occurred mainly in 4-, 6-, and 8-in.-diameter cast-iron 

pipe (sand cast) with fixed (cement or lead caulked) bell-andspigot joints. The breaks were due to tension, compression, 

or bending associated with differential settlement, especially 

in areas of liquefaction. Corrosion of the pipe and fittings 

also played a part in some of these breaks. The mains in the 

Marina District, which were installed in the 1930's and earlier, were unlined (fig. 3). More than 100 repairs were reported in the Marina District out of a total of about 150 in the 

entire city. San Francisco is replacing the damaged pipe in 

the Marina District with 9,000 ft of ductile-iron pipe with 

rubber-gasket joints. Leaks in 20- and 30-in. water mains were 

fixed with repair couplings. Most of the water-main breaks in 

Alameda occurred in 6- and 8-in.-diameter welded-steel pipe 

because of joint corrosion. 

-- - - Service Area 

Pipe Break Location 

Main Pipe Breaks 

22 Number of Breaks 

Figure 2.-East bay, showing locations of 

water-main breaks reported by East Bay 

Municipal Utility District. 
PERFORMANCE OF THE BUILT ENVIRONMENT 

am Break Location 

Figure 3.-Marina District of San Francisco (fig. I), showing locations of water-main breaks reported by 

San Francisco Water Department. 

Approximately 100 service-connection breaks were reported in the central San Francisco Bay area in connections 

made of galvanized iron, copper, and polyvinyl chloride 

(PVC). 

In San Francisco and the east bay, no physical damage 

to water-storage facilities or water-pumping plants was reported. The most significant impact of the earthquake on 

water and wastewater systems was a power outage to facilities lasting several hours to several days. San Francisco has 

400 million gal of water stored at high elevation within the 

city. The San Francisco Fire Department has an independent 

water storage and distribution system for fire suppression. A 

break in a 12-in.-diameter line and damage to hydrants 

drained a 750,000-gal tank that supplies water to the lower 

zone of the system in about 20 minutes; this system and its 

response are described in more detail in another chapter of 

this report. 

Eight hydropneumatic water-pumping plants in San 

Francisco, which provide pressure to higher elevations, lost 

power for 4 to 10 hours. The area served by these plants had 

enough water under lower pressure for public fire protection. The city is budgeting funds to purchase portable generators for this area. A dual-drive (diesellelectric) pump, in 

the central part of the city, had a 4-hour fuel supply in a day 

tank, which was to be replenished by fuel pumped from an 

auxiliary fuel tank. After the earthquake, the electric fuel 

pump lost its commercial power, and the dual-drive pump 

stopped when the fuel in the day tank was depleted. The San 

Francisco Fire Department uses the fire-engine pumpers connected between fire hydrants to pump water to higher elevations when necessary. 

Treasure Island, a U.S. Navy facility in the middle of 

San Francisco Bay (fig. I), is served by a water-pumping plant 

in San Francisco and a pipeline on the San Francisco-Oakland Bay Bridge. During the 3-day power outage after the 

earthquake, water service was discontinued. The U.S. Navy 

connected an emergency-power generator to activate the water-pumping plant. Some broken water mains and sewers were 

reported on the island. 

No damage to water-treatment plants was reported in 

the central San Francisco Bay area. A break occurred in a 

60-in.-diameter modified prestressed-concrete-cylinder rawwater-inlet line to the Sobrante Water Filtration Plant (fig. 

1); a separation occurred in the weld of the spiral-welded 
WATER AND WASTEWATER SYSTEMS A5 1 

cylinder. An 8-ft section of similar pipe was welded into place, 

and service was restored within 4 days (fig. 4). A compression failure of bell and spigot joints occurred in a 20-in.-diameter cast-iron pipe installed in 1916 under a 20-ft-thick 

fill. The pipeline was isolated by valves and abandoned, and 

because of redundancy, no customer was out of water because of this failure. A building housing a booster water-pumping station (5,500 gal per minute [gpm]) in Berkeley (fig. 1) 

was severely stressed, but it continued to operate because the 

electrical and mechanical equipment was undamaged. 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

A loss of water supply occurred in those areas with damaged water mains and areas affected by a power outage to 

pumping plants. Repair crews in San Francisco were slowed 

down while working adjacent to buildings on the verge of 

collapse; they needed rotating lights on their equipment to 

indicate the emergency nature of the work. The volume of 

paperwork required by the Federal Emergency Management 

Agency (FEMA) to be eligible for reimbursement was time 

consuming. The city had adequate repair materials and was 

able to resupply its stock from manufacturers on short notice. 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

Shortly after the earthquake, San Francisco Water Department personnel returned to the city yard and were supplemented by an apprentice class in progress in the yard at the 

time of the earthquake. Personnel worked on repairs around 

the clock. San Francisco Water Department workers staffed 

the city's emergency-operations center (EOC). An emergencypower generator provided electrical power to the yard offices and the normal 24-hour water-trouble office. Telephone 

lines were saturated; however, mobile radios worked well. 

The yard's emergency-power generator, which is tested 

weekly under load, operated as expected. The fuel pumps 

were not on emergency power, and the refueling of emergency repair vehicles and equipment was delayed until a 

portable generator was connected to the fuel pumps. 

In Oakland (fig. I), the water-operations-control center 

lost electrical power for several hours until an emergencypower generator was connected, but it still remained in service. An alternative EOC is needed in case the main center is 

out of service; EOC7s need emergency-power generators in 

case of a longer power outage. Additional emergency supplies, portable lights, portable pumps, portable generators, 

and pipe need to be distributed throughout the service area in 

the event that the central warehouse is out of service. 

SOUTH SAN FRANCISCO BAY AREA 

Water is imported to the south San Francisco Bay area 

from the delta by way of the South Bay Aqueduct of the State 

Water Project; from the San Luis Reservoir by way of the 

Santa Clara Conduit of the San Felipe Project, a division of 

the U.S. Bureau of Reclamation's Central Valley Project; and 

from the Sierra Nevada by way of the Hetch Hetchy Aqueduct. The local water supply consists of wells pumping from 

the ground-water basin and water collected from a few streams 

and springs. No damage was reported to the aqueducts or 

aqueduct reservoirs. 

Figure 4.-Damaged 60- 

eter raw-water line to the 

Water Filtration Plant. 

in, 

s< 
PERFORMANCE OF THE BUILT ENVIRONMENT 

EARTHQUAKE DAMAGE AND RESTORATION 

A minor leak (400 gpm) occurred in one of the two legs 

of the Santa Clara Conduit where it crosses the Calaveras 

fault east of Gilroy. The 96-in.-diameter conduit separates 

into two 66-in.-diameter legs for the 2,000-ft crossing of the 

fault zone. The rubber-gasket joint on the 66-in.-diameter 

prestressed-concrete-cylinder pipe pulled slightly apart. The 

leg was gated off on the day after the earthquake, and the full 

water requirement was supplied by the other leg as designed. 

Several air valves failed because of inverted-pendulum action on a few of the feeder lines from the conduit. The water 

supply from the State Water Project system was undisrupted. 

Approximately 120 water-main repairs were reported in 

the area of San Jose, Cupertino, Campbell, Los Gatos, and 

Los Altos. These leaks occurred in water mains ranging in 

diameter from less than 4 to 37 in. of steel, cast iron, asbestos 

cement, and ductile iron, three-fourths of which were in 25- 

to 30-year-old steel pipe with limited corrosion protection. 

More than half of the leaks were holes in the pipe caused by 

corrosion; others were caused by pulled joints and circular 

breaks. Most of the leaks occurred in the Los Gatos area. 

Approximately 10 service-connection repairs were reported. 

Several water tanks were damaged in the Los Gatos-San 

Jose area. An unanchored 100,000-gal bolted-steel tank built 

in 1966 had an "elephant's foot" buckle. Panels were unbolted 

and replaced with new panels of the same size, and the tank 

was back in service within 3 days. The inletloutlet underneath a 700,000-gal welded-steel tank built in the 1950's separated from the floor plate. The floor plate and inletloutlet were 

reconstructed, and the tank was back in service in 1% days. A 

10,000-gal redwood tank collapsed and was replaced with a 

10,000-gal welded-steel tank. 

In Los Altos Hills, a 1.1 -million-gal posttensioned-precastconcrete tank failed (fig. 5). This tank, constructed in 1962, used 

precast vertical wall panels wrapped with posttensioned wire 

and coated with gunite. A 4-in.-wide rupture along a vertical 

joint released the water from the tank, which was nearly full. 

No damage or disruption was reported to booster waterpumping plants or wells except for the a power outage for as 

long as 4 days. 

Four major water-treatment plants supplying treated 

water are located in the south San Francisco Bay area. Three 

of the four upflow clarifiers at the Rinconada Water Treatment Plant, constructed in 1968 with a capacity of 80 million 

gal per day (mgd), sustained wave-action and differentialmovement damage to the interior metal structure. A laboratory worker reported that the wave almost reached the top of 

a 30-in.-high railing around the basin. Inside each clarifier is 

floculator-center-feed clarifier equipment supported on a 39- 

in.-diameter steel column. This column, anchored at the base (a 

pendulum), rotated and cracked the casting of the rotatingfloculator gear-drive housing. About half of the radial launderers (wiers) pounded against and tore away from the clarifier 

walls. Some of the launderers fell down on and jammed the 

rotating sludge scraper (fig. 6). A fourth clarifier, which was 

empty at the time of the earthquake, was undamaged and was 

placed into service within 24 hours. One of the damaged clarifiers was put back into operation as a static chemical mixer for 

direct filtration, without removing the damaged equipment. The 

plant operated at 50-percent capacity, adequate for the winter 

demand, while a contractor repaired the other clarifiers. The 

water-quality laboratory performed well, even though some 

unanchored equipment moved. Restraining devices kept bottles 

containing chemicals on their open shelves (fig. 7). 

At the Montevina Water Treatment Plant, constructed in 

1970 with a capacity of 20 mgd, baffling in the coagulation 

basins was destroyed by wave action. The baffling was replaced 

by agency crews. A broken 30-in.-diameter raw-water line to 

the plant from the Austrian Dam was repaired in 1 day. No damage to the Penitencia (constructed in 1974 with a capacity of 40 

mgd) or Santa Teresa (constructed in 1989 with a capacity of 

100 mgd) Water Treatment Plants was reported. At a watertreatment plant (with a capacity of 10 mgd) near Tracy, 45 mi 

northeast of the epicenter, sloshing of water moved the center 

Figure 5.-Failure in 1.1 -million-gal posttensioned-precast-concrete 

water tank in Los Altos Hills. 
WATER AND WASTEWATER SYSTEMS A53 

column, causing the sludge scraper to bind against the clarifier 

structure. The plant was shut down, and the system was supplied 

from wells. 

DAMS AND RESERVOIRS 

The principal dams and water-distribution reservoirs in 

the central San Francisco Bay area were aerially inspected on 

the day after the earthquake by the California Division of Safety 

of Dams or the U.S. Army Corps of Engineers and were inspected on the ground within hours after the earthquake by their 

owners or consultants. Most reservoirs were at a low level because of third-year drought conditions in California. 

The Austrian Dam, constructed in 1950 with a capacity 

of 6,200 acre-ft, had cracks in the embankment and spillway. 

The embankment cracks were excavated and recompacted, 

and the spillway cracks were filled with epoxy. The Lexington Dam, constructed in 1952 with a capacity of 21,200 acreft, had transverse cracking at the abutments, which was 

repaired by recompaction. 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

Officials issued an advisory to boil water in Los Gatos 

for 1 day because the Montevino Water Treatment Plant was 

Figure 6.-Damaged water purifier at the Rinconada Water Treatment Plant. 

Figure 7.-Chemical shelves in 

water-quality laboratory at the 

Rinconada Water Treatment Plant, 

showing restraining devices. 
A54 PERFORMANCE OF THE BUILT ENVIRONMENT 

out of service and many water-main leaks were reported. This 

measure was precautionary, and no water contamination was 

detected. The Rinconada Water Treatment Plant, with 15 million gal of stored treated water, supplied Cupertino initially 

while the plant was being brought back into operation. When 

this limited operation began, the water supply was restored to 

Los Gatos. The loss of power was a hindrance to restoration 

of the water supply, indicating a need for emergency-powergeneration facilities and a complete set of system reference 

drawings to be located at the EOC. Private contractors were 

valuable in the restoration process; however, it was reported 

that they were not as efficient as the agency forces. 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

Offduty employees at water and wastewater agencies 

returned to their normal work locations shortly after the earthquake. The larger agencies operated by using their mobile 

radios because most telephones were blocked as result of the 

high volume of calls. A more reliable, direct communication 

link needs to be established between regional water retailers 

and wholesalers, because of postearthquake problems with 

the public telephone system. 

MONTEREY BAY AREA 

The Monterey Bay area relies for its water supply on 

stream and spring flows, and pumping from ground-water 

basins. 

EARTHQUAKE DAMAGE AND RESTORATION 

In the area of Hollister, Watsonville, Pajaro, and Sunny 

Mesa, approximately 60 water-main repairs in 4-, 6-, and 8-in.- 

diameter pipe were reported, as well as an unknown number of 

leaks in the Moss Landing area, where severe liquefaction occurred. Failure modes included push-on-joint failures and bell, 

circumferential, and longitudinal cracking. Some of the leaks 

occurred in areas of liquefaction and at bridge abutments. In 

the Watsonville area, most leaks occurred in cast-iron and 

asbestos-cement pipe; ductile-iron pipe with rubber-gasket 

joints was reported to have performed well in the earthquake. 

In Hollister, most water-main breaks occurred in 4- and 

6-in.-diameter cast-iron pipe with lead-caulked joints within 

the Calaveras fault zone. Asbestos-cement pipe was reported 

to have performed well in the earthquake. Approximately 70 

service-connection leaks were reported in the Hollister area. 

In Hollister, a 2-million-gal welded-steel tank, constructed in the l96O7s, performed well in the earthquake; however, a pulled coupling in a private-building 6-in.-diameter 

fire-service line, caused by collapse of an adjacent unreinforcedmasonry building, almost drained the tank. 

No damage or disruption was reported to 14 wells or 

pumping plants in Hollister, except for a cracked well-discharge pipe, a broken air valve (inverted-pendulum action), 

and the loss of power. 

In Watsonville, a 1-million-gal welded-steel tank, constructed in 197 1, buckled on one side at the shell-roof connection because of failure or yielding of the rafter bracket. 

The electronic water-level-transmitting device at this tank was 

damaged by wave action and required repair. Also at this tank, 

the pilot line on the altitude valve broke, causing a minor 

leak. In spite of this damage, the tank did not leak and continued to operate. Watsonville's nine other reservoirs performed 

well in the earthquake. 

In Pajaro, an unanchored 600,000-gal welded-steel tank, 

on a wick (vertical gravel) drains foundation, constructed in 

1986 by using an American Water Works Association (AWA) 

Standards design, performed excellently in the earthquake, 

even though located in a river bottom, a potentially liquefiable area. At Sunny Mesa, a 200,000-gal. welded-steel tank, 

constructed in 1968, was tilted with its base lifted off its foundation on one side and settled as much as 2 in. on the other 

side; however, it did not leak. An 8-in.-diameter tee on the 

inledoutlet broke and released all but 4 ft of water in the tank 

before the tank outlet valve was closed. No damage was reported to an elevated tank at Moss Landing. 

In Watsonville, a slow-sand-filter water-treatment plant, 

constructed in 1930 with a capacity of 2.5 mgd, treats the 

stream- and spring-water supply. The concrete basins leaked, 

apparently at the construction joints, and the plant was put 

out of service. A 150-lb chlorine cylinder at a booster waterpumping facility toppled when its anchorage failed, causing 

release of chlorine gas. 

The Newel1 Creek Dam in the Monterey Bay area (see 

below), constructed in 1960 with a capacity of 8,700 acre-ft, 

had a longitudinal crack on the upstream face, which was 

excavated and recompacted. All reservoirs were considered 

capable of handling the winter runoffi however, they were 

closely monitored during reservoir filling for any possible 

damage that may have gone undetected. 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

In downtown Watsonville, water-main breaks and power 

outages made it impossible to keep the area pressurized and 

created the potential for contamination. A notice to boil water was issued within 24 hours after the earthquake and maintained for 3 days, until water-quality tests were completed. 

No contamination was found. In Hollister, the loss of commercial power and the absence of emergency-power generators allowed the water in the sewage system to rise to the 

level of the manhole covers, creating, in conjunction with 

water-system damage, possible contamination of the water 

system. Notice was issued to boil water or to use water available from U. s. National Guard trailer tanks until the safety 
WATER AND WASTEWATER SYSTEMS 

of the water system could be ensured. No contamination was 

reported. Generators for operating the sewage pumps were 

obtained about 14 hours after the earthquake. A loss of water 

service occurred to areas of broken water mains and to about 

20 percent of the other areas for as long as 2 days because of 

a power outage; a few customers were without a public water 

supply for 2 weeks. 

An auxiliary emergency-power generator and four auxiliary engine-driven pumps in the Watsonville area continued to 

operate, but one of the pumps temporarily lost a cooling-water 

line. Supply of fuel to emergency engine generators became a 

problem because the supply tanks at the sites were not big enough 

to last for more than a few hours. Supply trucks were not readily 

available because of the extreme demands for them and because 

of traffic delays caused by police barricades, detours, damage 

to roads and bridges, and collapsed buildings. Water emergencyrepair crews and equipment had access difficulties, which had 

not been considered in developing emergency-response plans. 

More isolation valves and regular valve maintenance were 

needed to facilitate the isolation of smaller areas for repair. In 

Watsonville and Pajaro, the headquarters' office radios had no 

emergency-power generator, and because of the power outage, 

the offices were unable to directly communicate with the field; 

however, communications were available between service-vehicle radios. Maintenance personnel put in long hows of work. 

After the first day, some people were ordered to go home and 

sleep; however, others continued to work. In the future, work 

shifts should be scheduled to reduce fatigue during recovery 

operations. 

The power outage in the Monterey Bay area lasted from 

1 to 3 days. Auxiliary emergency-power generators were 

placed in operation; however, too few of these generators were 

available to serve the area's needs, and they lacked the fuelstorage capacity for long power outages. The high volume of 

calls caused disruptions in telephone service. A reliable system is needed to monitor repairs and system operations so as 

to quickly establish a priority for repairs. 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

The Watsonville city and regional emergency-response 

plans worked well; however, water and wastewater operations 

need to be included in local and regional plans. In Hollister, the 

road to the main water tank was jammed with vehicles because 

other government offices are located on the same road, and 

workers had trouble getting through to check the tank. Enough 

maintenance people, materials, and equipment were available 

to repair the water system; however, only two people in Watsonville 

knew how the system operates. The need to quickly return the 

system to operation required them to work long hours without 

relief, emphasizing the need for cross-training of personnel in 

system operation. The notice to boil water in Watsonville pointed 

to a need to establish State-wide guidelines for water-qualitytesting procedures and public notification. 

SANTA CRUZ AREA 

In the Santa Cruz area, the water supply is from wells 

pumping from the ground-water basin, and from surface 

streams and springs. 

EARTHQUAKE DAMAGE AND RESTORATION 

Approximately 240 water-main repairs were reported in 

the Santa Cruz area. Most of the leaks occurred in cast-iron 

pipe with leaded joints and small-diameter galvanized pipe 

at the threads. Asbestos-cement and ductile-iron pipes with 

rubber-gasket joints were mostly undamaged. The breaks 

occurred in %- to 12-in.-diameter pipe in unstable ground (alluvium and beach areas) and to threaded steel pipe acquired 

from the original private or mutual water system. More than 

250 service-connection problems were reported. 

Of the wells and booster water pumps in the Santa Cruz 

area, only three wells in the San Lorenzo Valley were damaged. The wells filled with sand and were redrilled. At one 

booster water-pumping plant, a transformer fell off the wall 

mounting, but it was undamaged and was remounted. In the 

Soquel area, the only reported damage was minor altitudevalve malfunctions in some of 18 water-storage reservoirs (6 

million gal). One tank and the adjacent hydropneumatic water-pumping plant were taken out of service as a precautionary measure because of the appearance of ground-surface 

cracks on the steeply sloping site. 

In Scotts Valley, the unanchored 400,000- and 750,000- 

gal welded-steel tanks (on concrete ringwalls) were damaged 

at the wood-roof connection to the tank shell. The two tanks 

drained because their inflow and outflow pipes broke. All of 

these tanks were repaired and returned to service. No damage was reported to an unanchored 1.25-million-gal weldedsteel tank, constructed in 1983 and situated on a concrete ring 

located on bedrock, using AWWA Standards design. 

The San Lorenzo Valley lost five redwood tanks ranging 

in size from 10,000 to 150,000 gal. These tanks were replaced 

within the year. 

In the Santa Cruz Mountains, several small private and 

mutual water companies were completely devastated by the 

earthquake. The area, which was originally developed as a 

summer-cabin retreat, had grown into a year-round commuter 

residential area. Most of the water systems grew from an individual well, spring, or stream pump without any planning, 

design, or financing. The facilities consisted of redwood and 

bolted-steel tanks, PVC and galvanized-iron piping, small 

pumps, and small water-treatment equipment without any 

seismic design. The tanks and inflow and outflow piping were 

severely damaged. Some tanks collapsed, piping broke above 

and below the ground, equipment was damaged, and power 

was lost for several days. In several places, the motion of the 

tank damaged piping that had inadequate flexibility (fig. 8). 

Because of third-year drought conditions in California, many 
A56 PERFORMANCE OF THE BUILT ENVIRONMENT 

of the residents maintained their own water-storage tanks. 

These tanks continued to be filled by tanker trucks because 

in some areas a public water system was not available until 

March 1990. Limits in engineering and maintenance staffing? system maps? financing? and mutual aid made it extremely difficult to restore these systems. The Coachella 

Valley Water District? Santa Clara Valley Water District? Los 

Angeles Department of Water and Power? and other agencies provided personnel and equipment for field repair and 

engineering assistance. 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

In Aptos? Capitola? and Soque17 water service was interrupted for only a few hours? if at all7 except for the area served 

by the above-mentioned booster water-pumping plant with 

the transformer problem? which was out of service for as long 

as 3 days. The city of Santa Cruz issued an advisory alert to 

boil water for 7 days. No positive bacteriologic samples were 

found. About 40 percent of the water-supply system was without water initially? 90 percent of water service was restored within 

24 hours? and complete restoration was effected within 4 days. 

In Scotts Valley? the impact of the earthquake was limited; only one break was reported in the asbestos-cement pipe 

that is used in 90 percent of the water-supply system. Generators were used on a rotating basis to operate wells and 

pumps. The San Lorenzo Valley lost power for as long as 4 

days; however? 80 percent of residents received water by using portable generators to operate the wells and pumps. An 

advisory notice was in effect for 7 days to boil or chlorinate 

the water? but no bad water-quality samples were found. 

Closed bridges and landslides restricted the movement 

of repair teams because these obstacles required detours and 

slowed the effort to reach critical locations. Crews were concerned about personal safety because of potential hazards from 

damaged buildings? landslides, and fallen trees? as well as 

from working in unshored trenches during aftershocks. A 

notice was issued to boil water until water-supply management was satisfied there was no longer a need. A more uniform water-boiling policy is needed. 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

In the area of Aptos? Capitola? and Soque17 the EOC7 a 

part of the emergency-operations plan, was fully staffed within 

5 minutes after the earthquake. Inspection teams of two people 

were established to survey the facilities; their first priority 

was to inspect and secure the water tanks. The telephone system was saturated? and so teams relied on the use of mobile 

radios and the headquarters radio? which had emergency 

power. Three contractors with experience in waterworks volunteered and supplemented the agency7s crews in the restoration. People need to be cross-trained to handle emergency 

calls. 

In Santa Cruz? crews were dispatched within an hour to 

inspect the reservoirs and the Newel1 Creek Dam, and they 

began to repair leaks within 2 hours. Crews worked in 12- 

hour shifts with the assistance of three private contractors. 

Emergency-power supplies need to added for two major 

pumping plants. 

WASTEWATER SYSTEMS 

Few sewer-main breaks have been identified since the 

earthquake because most sewage flows with gravity and so 

Figure 8.- 

ing in the 

damaged 

flexibility 

-Tank 

Santa 

becau 

inlet 

Cruz 

;e of 

-outlet pipMountains 

inadequate 
WATER AND WASTEWATER SYSTEMS 

wastewater does not normally appear at the surface of the 

ground. However, at least as many sewer-main breaks as water-main breaks may be assumed to have occurred, especially 

in the same areas of unstable ground. Contacts with wastewater agencies indicated that they were performing videocamera surveys of the sewer mains to determine the extent of 

the damage. Investigators identified breaks in sewer pressure 

lines (force mains) when power was restored to sewage-pumping stations. 

CENTRAL SAN FRANCISCO BAY AREA 

EARTHQUAKE DAMAGE AND RESTORATION 

A six-block area of Alameda constructed on 1960's 

dredged fill underwent severe liquefaction, causing damage 

to the sewer mains. The proposed method of repair was to 

thread a polyethylene-plastic sleeve inside the damaged 4- 

and 6-in.-diameter vitrified-clay pipe. 

No major structural damage was reported at the regional wastewater-treatment plants in San Francisco and Oakland; 

however, the power outage caused some short-time releases 

of sewage into the Pacific Ocean and San Francisco Bay. The 

Oakland regional plant lost commercial power from two feeds 

for 7 hours. At an industry upstream from the plant, a 20,000- 

gal caustic-chemical tank drained into the sewer system. This 

drainage raised the pH to 11 in the sewer system, causing the 

biomass already affected by oxygen starvation to die and severely disrupting the plant's secondary activated-sludge process. No power was available to run the secondary-treatment 

Figure 9.-Failed roller-guide assembly on digester cover at regional 

wastewater-treatment plant in Oakland (fig. 1). 

system because the sludge gas-engine generators were not 

designed for emergency startup. A floating digester cover 

rotated, damaging the 12-in. cast-iron roller guides. Several 

failures were reported: The roller-guide-assembly anchorage 

failed on most guidks, on some anchorages the guide assembly failed, and on one anchorage the wheel axles failed (fig. 

9). A similar sloshing problem was reported on four of the 

eight digester covers at a wastewater-treatment plant near 

Sacramento, 100 mi northeast of the epicenter. 

In San Francisco, most of !he observed damage to the 

combined (wastewater and storm water) sanitary sewer system involved frames around catchbasins and manholes. Because it is a combined system, a large-capacity conveyance 

facility around the city holds storm water during storms (before treatment), reducing spillage into the bay while the wastewater-treatment plants were out of service because of the 

power outage. Observed damage included circumferential 

cracks in 84- and 96-in.-diameter outfall lines and a leak in a 

pressurized 66-in.-diameter reinforced-concrete pipe with 

rubber-gasket joints. 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

Almost no wastewater-system users in the central San 

Francisco Bay area were affected by the earthquake, except 

in localized areas where minor blockage or loss of a force 

main may have occurred because of loss of power for pumping. An emergency-power supply is needed for sewage-pumping plants. The sewer system probably was unavailable in 

unstable areas where significant breaks occurred in the water-system piping; however, because water was unavailable, 

the sewers were not much needed at the time. 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

The San Francisco and Oakland EOC's operated as 

planned (see section above entitled "Water Systems"). In 

Oakland, the sludge gas-engine generators were modified to 

operate automatically under emergency conditions. In both 

cities, sewage discharges into the ocean and the bay could 

have been avoided with an adequate emergency-power supply and the automatic startup of emergency-power generators. 

SOUTH SAN FRANCISCO BAY AREA 

EARTHQUAKE DAMAGE AND RESTORATION 

Several regional wastewater-treatment plants are located 

in the south San Francisco Bay area. Structurally, they all 

performed well in the earthquake. 

The Pa10 Alto Wastewater Treatment Plant, constructed 

in 1938 and expanded in 1972 and 1986, with a capacity of 
A58 PERFORMANCE OF THE BUILT ENVIRONMENT 

40 mgd, serves Mountain View, Los Altos, Los Altos Hills, 

Stanford University, Palo Alto, and East Palo Alto. Fiberglass 

scum troughs were damaged by wave action in four rectangular clarifiers. The troughs were attached to the concrete 

wall with a fabricated fiberglass bracket, which broke at the 

angle point (fig. 10). Some of the troughs fell onto the sludgesweeping scraper in the bottom of the clarifier, causing the 

scraper to jam. In one of two circular clarifiers, the pendulum-action vertical center support rotated from the earthquake 

motion, causing the radial scum trough to bind. The other 

circular clarifier was dry at the time of the earthquake. 

A small leak occurred at the concrete junction box between the tertiary dual-media filter and the two 96-in.-diameter reinforced-concrete effluent lines. On the roof of the 

primary sedimentation basins, several of the 2- by 3-ft aluminum access covers fell into the basin when dislodged by sloshing sewage. Workers removed the scum troughs and access 

covers from the bottom of the basins and freed the radial scum 

trough in 2 days. The plant was put back in operation within 

2 hours by activating the empty circular clarifier and by storing effluent in the effluent-holding tanks, discharging only 

tertiary water into the bay. The sludge-burning incinerator 

was secured for a time until it could be inspected. No damage 

was reported to the sewage-collection system feeding this 

plant. The plant lost commercial power but operated by using 

emergency-power generators. 

The cities of Fremont, Newark, and Union City are served 

by the Alvarado Wastewater Treatment Plant, constructed in 1980 

and expanded in 1987 with a capacity of 35 mgd. The plant, 

located on a 20-ft-thick engineered compacted fill, sustained no 

structural damage from the earthquake. The chlorine building, 

which is constructed on piles, also was undamaged. No power 

outage occurred to the plant; however, it has 100-percent backup 

emergency-power generators. Wave action tore loose the center-well fiberglass baffles in two primary and two secondary 

clarifiers. The plant has six primary and six secondary clarifiers; however, only four of each are operated under normal conditions. The plant operation was switched to the other clarifiers. 

Plant workers repaired the damaged baffles in 2 days. A crack 

was reported in a 12-in.-diameter cast-iron pipe that fed an outof-service digester which stored reclaimed water. The pipe was 

repaired after the digester was drained and cleaned. Two of three 

booster sewage-pumping stations lost power; however, the emergency-power generators operated automatically. The generators 

had been tested weekly under load. No leaks were detected in 

the sewage-collection system. A consulting civil engineer inspected the plant after the earthquake, and the only damage 

noticed was superficial cracking, which was repaired by pressure grouting. 

Men10 Park, Redwood City, San Carlos, and Belmont 

are served by the South Bayside Wastewater Treatment Plant, 

with a capacity of 24 mgd, where no structural damage was 

reported. The damage to the fiberglass baffles in the clarifiers, caused by sloshing water, was almost identical to the damage sustained at the Alvarado Wastewater Treatment Plant. 

Baffles were replaced with a modified design that includes 

straps to keep them from falling into the clarifier. 

In the City of San Mateo Wastewater Treatment Plant, 

the multiple-hearth sludge incinerator was damaged. The 

incinerator's center shaft probably moved back and forth at 

least 2 ft in each direction, damaging the center shaft and 

furnace refractory bricks. Other damage included waterline 

and gasoline breaks and damage to fiberglass chlorine contact-basin baffles, caused by sloshing water. 

No damage was reported to the San Jose wastewatertreatment facilities. 

Figure 10.-Damaged bracket on 

scum trough of clarifier at the Palo 

Alto Wastewater Treatment Plant 

(fig. 1). 
WATER AND WASTEWATER SYSTEMS A59 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

No wastewater-system users in the south San Francisco 

Bay area were affected by the earthquake because of the availability of an emergency-power supply and redundant components. At the Palo Alto Wastewater Treatment Plant, the fallen 

scum troughs and access covers in the clarifier basin, which 

was full of cloudy sewage, were difficult to see and thus difficult to remove. 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

The Palo Alto Wastewater Treatment Plant, which operates continuously, exercised its emergency-response plan. The 

plan's first priority was to see that the emergency-power generators were started to maintain the biologic-treatment system, which controls the quality of the water discharged into 

the bay. The plant's four emergency-power generators (250- 

500 kW), two fixed and two portable, which are tested monthly 

under load, operated satisfactorily after the earthquake. The 

plant purchased an additional portable 500-kW unit. Telephone-line saturation was a problem; however, activities were 

directed by using the city's radio, radio-equipped vehicles, 

and four portable radios. 

At the Alvarado Wastewater Treatment plant, which also 

operates continuously, the emergency-response plan was not 

exercised. All personnel reported to the plant after the earthquake. A consultant had performed an earthquake-vulnerability assessment on the plant before the earthquake. The 

high-volume telephone problem was resolved by interconnecting the plant's mobile-radio system with a county public-works radio system. 

MONTEREY BAY AREA 

At the Hollister Wastewater Treatment Plant, primary 

effluent water is put into lagoons for evaporation. A dike on 

one of four lagoons slumped slightly; however, the lagoons 

continued to operate. The extent of sewer-main damage was 

determined by further inspection. 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

Almost no wastewater-system users in the Monterey Bay 

area were affected by the earthquake, except in localized areas with small blockages or power outages, which inactivated 

the force mains. In areas of water-main damage, sewer mains 

probably also were damaged; however, without water, the 

sewer system was not much needed. 

The difficulties with traffic, telephone, radio, and personnel training were the same as those in the water system 

(see section above entitled "Water Systems") 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

The problems and needs of the wastewater systems in 

the Monterey Bay area are the same as those of the water 

systems (see section above entitled "Water Systems"). 

SANTA CRUZ AREA 

In the Santa Cruz area, a county sanitation district collects sewage from the built-up areas of the county, except the 

incorporated cities of Scotts Valley and Santa Cruz. This system is for collection only; treatment is provided by the city of 

Santa Cruz. Although it is basically a gravity system, it has 

several sewage-pumping stations, all of which have emergency-power generators. 

EARTHQUAKE DAMAGE AND RESTORATION 

EARTHQUAKE DAMAGE AND RESTORATION 

In Watsonville, the earthquake did not cause blockage of 

the sewerlines, but preliminary inspection of many of the sewers indicated broken pipes, misalignment, and grade changes. 

The pipes were concrete with rubber-gasket joints; older pipes 

may be cement-mortar caulked. A preliminary inspection indicated that the damage could be widespread, and further inspection by video camera is required. The liquefaction at Front Street 

caused a sewer grade to reverse and broke other parts of the 

sewer. The vitrified-clay pipe pulled apart at the joints. The 

onland portion of the 36-in.-diameter welded-steel, cementmortar-lined outfall developed two leaks (joint separation) where 

it crossed a low-lying unstable-soil area. Draining the area of 

water was not feasible, but divers made repairs by applying 

mastic. The advanced primary wastewater-treatment plant, which 

was upgraded in 1985, was virtually undamaged; it had been 

designed to withstand seismic forces. 

The most serious damage in the Santa Cruz area was 

several leaks in the county's 36-in.-diameter steel, plasticlined, cement-mortar-coated force main in a ravine near the 

San Lorenzo River. The main, which carries 5 to 8 mgd, separated at a joint. The joint was gated off, and the sewage was 

bypassed by a temporary pipeline into Monterey Bay. The 

site had to be drained of water with well points, and in 9 days 

a steel butt strap was welded into place to close the 8-in. gap. 

Two more leaks that occurred in the vicinity were also repaired with difficulty, because water was present at the site 

and utilities were nearby. Several leaks or alignment problems were reported, but unless the difficulty was serious 

enough to block the flow or cause contamination problems, 

immediate repairs were not undertaken because of other problems facing the county. 
A60 PERFORMANCE OF THE BUILT ENVIRONMENT 

The city of Santa Cruz operates the regional wastewater-treatment plant, constructed in 1965 and expanded in 1976 

and 1989, with a capacity of 17 mgd, which collects sewage 

from the city and processes the county flow from a 36-in.- 

diameter force main. No structural damage to the plant, which 

is constructed on piles, was reported, and it continued to operate after the earthquake. In three or four places, 6-in.-diameter ductile-iron-pipe below-grade structure-wall penetrations 

were sheared off when the ground settled away from the pilesupported structures. The pipelines were relocated to penetrate the structure wall above grade. A construction joint on 

the sedimentation basin's effluent channel cracked, causing 

leakage and slight undermining of the structure. The joint 

was repaired within 24 hours of the earthquake. No damage 

was reported, even though liquefaction occurred along the 

alignment of the four lines approaching the plant (the city's 

30- and 54-in.-diameter, the county's 36-in.-diameter, and 

Scotts Valley's 12-in.-diameter treated-wastewater force 

mains). The Scotts Valley line bypasses the plant and joins 

the joint outfall line. About 800,000 gal of raw sewage was 

released in Santa Cruz as a result of the 30- to 35-hour loss of 

power to the sewage-pumping stations. Miscellaneous breaks 

in the 6- to 54-in.-diameter collection system were reported. 

The plant lost power for almost 24 hours, but it operated with 

an emergency-power generator. Only three portable generators were available for the 17 sewage-pumping stations. 

No serious problems were reported at the Scotts Valley 

wastewater-treatment plant, constructed in 1985, with a capacity of 0.95 mgd, other than a few isolated masonry cracks. The 

plant continued to operate for 63 hours on emergency backup 

power. Because of a power outage at remote sewage-pumping 

stations, crews had to shuttle a trailer-mounted generator from 

station to station to avoid overflows, until they were able to 

purchase and hook up generators at each station. Miscellaneous 

damage to the 8- to 12-in.-diameter PVC-pipe system was reported. The Scotts Valley 12-in.-diameter force main to the ocean 

outfall, on the levee along the San Lorenzo River, separated at a 

bell-and-spigot joint. Contractor crews repaired it within 24 hours 

of the earthquake, without taking the pipe out of service. 

As with other wastewater systems, the Santa Cruz and 

Scotts Valley underground gravity facilities were thoroughly 

surveyed by video cameras. Most of the sewage-disposal systems in the Santa Cruz Mountains are of the private cesspool 

or septic-tank type. 

IMPACT ON USERS AND HINDRANCE TO RESTORATION 

Almost no wastewater-system users in the Santa Cruz 

area were affected by the earthquake, except in localized areas with small blockages or power outages to the sewagepumping plants supplying the force mains. The sanitation 

district's repair of the 36-in.-diameter main was impeded by 

high ground water, and a system of well points had to be installed to drain the construction area. Telephone service was 

saturated, and telephones remained unusable for 15 hours. 

The sanitation district's electrical power was out for 2 hours, 

but emergency-power generators were available and functioned properly. The district was short of trained personnel 

because county forces were busy with more critical functions. 

EMERGENCY RESPONSE AND FUTURE IMPROVEMENTS 

Santa Cruz County's emergency-response plan worked 

well; however, the sanitation district considered that the priorities set by the plan left the district on its own and even 

reduced its ability to respond rapidly. The city of Santa Cruz 

has a well-documented emergency-response plan, which includes fire and police radios in all vehicles. Better radio-communication procedures and specific assignments for personnel 

in emergency-response operations are needed. Santa Cruz is 

requesting the purchase of five emergency-power generators. 

Scotts Valley has an excellent emergency-response plan and 

is purchasing three additional generator units. In Scotts Valley, all public-works vehicles are equipped with two-way radios, and they have six hand-held radios. 

CONCLUSIONS AND 

RECOMMENDATIONS 

The biggest impact of the earthquake on water and wastewater systems was the loss of commercial power, especially 

because it lasted so long. Because of the chance that the electrical-power system will fail in an emergency such as an earthquake, the U.S. Environmental Protection Agency (EPA) requires 

either a dual power supply or an emergency-power supply at 

their newly funded treatment plants. 

The TCLEE reconnaissance group had insufficient time 

to contact all the water and wastewater systems in the earthquake-affected area; therefore, a complete survey is left to 

future researchers. Also, the group could not include all the 

available information in this report, and so these details are 

left to future researchers for study. 

On the basis of this preliminary reconnaissance survey, 

the 1989 Loma Prieta earthquake has reinforced the lessons 

learned in previous earthquakes that water and wastewater 

systems should do the following. 

Provide emergency power for critical operating, treatment, and support facilities.-Water- and wastewater-treatment facilities and emergency operations were significantly 

disrupted by the earthquake because of the loss of commercial power. Emergency power should be available on site at 

these facilities because generators are difficult to obtain and 

deliver after an earthquake. The emergency power should be 

installed, maintained, and tested as described by Schiff (this 

chapter). 

Maintain portable lightplants, generators, chlorinators, 

andpumps-Portable light plants are necessary for night-time 
WATER AND WASTEWATER SYSTEMS A6 1 

repair work. Portable generators can be used to operate portable pumps to drain construction sites or to operate portable 

chlorinators to disinfect repaired water mains. 

Develop a separate radio-communication system, independent of the telephone system.-After the earthquake, as is 

typical after similar earthquakes, the telephone system was 

blocked by a high volume of calls. Regional or city emergency radio-communication systems give priority to fire, police, and medical emergencies. A separate radio-frequency 

system should be available for dispatching repair crews and 

equipment to water and wastewater systems. A base station, 

an alternative base station, an emergency-power supply, and 

mobile units should be a part of this system (see Schiff, Tang, 

and others, this chapter). 

Maintain an inventory of repair materials, parts, and 

fuel.-No shortage of repair materials, parts, or fuel was reported for the medium-size to larger water and wastewater 

agencies; however, some agencies reported that their supplies 

of specific items were almost depleted. Some small agencies 

had essentially no inventory and had to order, and sometimes 

wait for, needed repair materials. 

Improve the State-wide mutual-aid program.-A utilities division of the California Office of Emergency Services 

(OES) coordinates the water, gas, and electrical mutual-aid 

program. Each activity is administered by a representative 

designated from a major utility as the State operating engineer to coordinate the program. Although volunteer mutual 

aid was available after the earthquake, both the organization 

and testing of the communication system for the OES need to 

be reviewed. 

Establish guidelines for State-wide emergency water-quality sampling and public notification.-Small and medium-size 

water and wastewater agencies who rely on outside water-quality laboratories and have no public-relations staff need some 

uniform guidelines as to what minimum testing is required to 

ensure that the water supply is potable in an emergency. Also, 

radio stations should be provided with sample news releases 

that they can use to tell the public when they should boil water 

in the case of a potentially polluted water supply. 

Conduct an earthquake-vulnerability assessment of system facilities.-Each water and wastewater agency should 

conduct an earthquake-vulnerability assessment of its system, either by outside consultants or inhouse engineering or 

technical personnel. These people need to be trained as to 

what to look for in evaluating the facilities. They should identify (a) simple and low-cost mitigation measures, such as anchorage of equipment, chemical or compressed-gas tanks, 

supply cabinets, and warehouse storage facilities; (b) mediumcost mitigation, such as emergency-power supplies, roof-towall connections, or wall-to-footing connections for buildings 

that house pumps or treatment equipment; and (c) facilities 

that require more detailed engineering analysis, such as large 

tanks, large buildings, and treatment plants. The detailed analysis could require demolition and complete reconstruction of the 

facility, resulting in a high-cost mitigation measure. 

Develop an emergency-response plan.-Each water and 

wastewater agency should have a simple emergency-response 

plan, even though many of these agencies normally operate 

on a continuous emergency-response basis. This plan should 

include, but not be limited to, emergency-reporting procedures, reporting locations, alternative assigned duties, training, provision for providing meals to field locations, a plan 

for inspecting critical facilities, a plan for an alternative operating center, and a method for exercising and updating the 

plan. 

Incorporate into local or regional emergency-response 

plans a more active participation by water and wastewater 

agencies.-In some places, an agency or its contractors had 

difficulty in entering secured areas because the agency had 

not been recognized in advance as an emergency-response 

organization. This difficulty could be alleviated by incorporating the agency into the local or regional emergency-response plan. 

Provide a method, possibly computer based, for logging 

problems and system operations to establish priority for repair activities.-During an emergency, many contacts to water 

and wastewater agencies are made by telephone, by radio, 

and through the EOC. A system needs to be developed to sort 

out the problems in order to establish a priority for restoration. 

Conduct a crosstraining program to include all personnel in emergency response.-Smaller agencies with limited 

personnel should crosstrain their office personnel in staffing 

the EOC, telephone switchboard, and radio; in understanding system operations; in logging operational data (pump, 

treatment, and valve operations); and in understanding the 

types of restoration activities (locations, crews, equipment, 

materials and time to complete the repair). The agency should 

collect data if it is eligible for disaster funds. 

Train personnel in appropriate communication procedures.-Personnel need to be trained in the operation of telephone and radio equipment, so that they can obtain the appropriate information in a minimum of time and dispatch this 

information to field crews. 

Conduct regular periodic emergency-response exercises.-Each emergency plan needs to be tested by regular 

and different simulated emergency scenarios, both inhouse 

and on a local or regional basis. One of the most critical parts 

of this exercise is to test the communication system, so as to 

show whether the plan needs to be modified. 

Provide flexible pipe joints.-Pipe with flexible joints, 

such as rubber-gasket, reinforced-concrete, vitrified-clay, 

ductile-iron, PVC, and asbestos-cement pipes, performed well 

in the earthquake; however, only a few of these pipes may 

have been installed in unstable areas. In areas of potential 

soil liquefaction, fully restrained flexible-joint pipes should 

be provided. Cast-iron, clay, and concrete pipe with rigid 

caulked joints; corroded steel pipe; and galvanized-iron screw 

pipe were the most heavenly damaged. 

Provide flexible pipe connections to wells, tanks, pumps, 

and other rigid structures.-Tank and well connection pip- 
A62 PERFORMANCE OF THE BUILT ENVIRONMENT 

ing was damaged during the earthquake because of differential movement. Where connecting piping was fitted 

with mechanical double-flexible joints, the piping performed well. 

Provide adequate anchorage for air valves and other 

heavy appurtenances that are installed in an inverted-pendulum position.-A few air valves installed on a small pipe in a 

vertical position broke at the threaded connection, owing to 

vibration. 

Design mechanical appurtenances in treatment-plant 

basin facilities for wave action.-Wave action (sloshing) and 

vibration caused by earthquakes can damage treatment-plant 

mechanical appurtenances. In both wastewater- and municipal water-treatment plants, digester and clarifier basins, scum 

troughs, launderers, and baffles were damaged, requiring a 

shutdown of operations. 

Provide for breakaway or fusible connections and (or) 

safety cables or chains to prevent malfunctioning mechanical equipment from interfering with other equipment in treatment-plant basins.-Differential movement between mechanical 

equipment and reinforced-concrete basins caused the mechanical equipment to undergo tension on one side and compression on the other side of the basins. The damaged equipment 

fell to the bottom of the digester or clarifier and caused a 

malfunction of the rotating or traveling sludge scraper at the 

bottom of the basin. 

Provide for redundancy in water and wastewater systems.-Linear waterlines and sewerlines should have redundancy by the use of piping loops, piping grids, multiple storage 

and pumping facilities, interconnected pressure zones, and 

alternative power supplies. 

Install isolation valves and establish a regular valvemaintenance program.-Isolation valves are important in isolating the waterlines and sewerlines in unstable ground, in 

poor soil, inareas of high landslide susceptibility, and at canyon and creek crossings. Reliable operating valves are necessary to minimize the size of areas that must be taken out of 

service for damage repair. 

Anchor water-quality -testing equipment and supply cabinets.-No damage was reported in water- and wastewatertesting laboratories; however, in other laboratories, equipment 

fell, small chemical-storage containers fell off shelves, and 

supply cabinets tipped over. Small chemical containers on 

open storage shelves should be restrained by a wire, bar, or 

shelf lip. Laboratory equipment should be anchored to the 

bench, a shelf, or a structural wall. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

WATER-DISTRIBUTION SYSTEM 

CONTENTS 

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tern in the 1989 Loma Prieta earthquake. A total of 135 buried pipes were reported damaged, ranging from 60-in.-diameter aqueducts to small-diameter cast-iron, asbestos-cement, 

and steel pipelines. The pipeline damage was correlated with 

peak ground velocity, soil conditions, pipeline diameter, pipeline materials, and corrosive soil conditions. In combination 

with data from other earthquakes, this paper presents new 

pipeline fragility curves for both ground shaking and permanent ground deformation hazards. Using these curves, this 

paper presents forecasts pipeline damage due to future larger 

earthquakes that can affect the EBMUD water-distribution 

system. 

INTRODUCTION 

This paper provides detailed documentary evidence of the 

performance of the East Bay Municipal Utility District 

(EBMUD) water-distribution system in the 1989 Loma Prieta 

earthquake. EBMUD was organized in 1923 under the Municipal Utility District Act of 1921. In 1928, EBMUD acquired the 

properties of the East Bay Water Co., a corporation formed by 

consolidation of 15 smaller companies, the oldest of which was 

incorporated in 1865 (National Board of Fire Underwriters, 

1933). Today, EBMUD's water-distribution system serves about 

1.2 million people; its service area comprises 21 cities in the 

east bay, including Oakland, Berkeley, San Leandro, San 

Lorenzo, El Cerrito, Kensington, Albany, Richmond, Pinole, El 

Sobrante, Rodeo, Crockett, Hercules, Walnut Creek, San Ramon, 

Alamo, Pleasant Hill, Orinda, Moraga, Lafayette, and parts of 

Hayward. The water-distribution system is bisected by the Hayward and Calaveras faults, which are capable of generating 

M=7.25 and 6.75 earthquakes, respectively. 

At the time of the earthquake, EBMUD's water-distribution system included 6 water-treatment plants, 175 treatedwater reservoirs (mostly tanks), 125 pumping plants, and 3,800 

mi of buried pipe. EBMUD also operated more than 20 office, warehouse, and maintenance buildings. 

ABSTRACT 

This paper documents the performance of the East Bay 

Municipal Utility District (EBMUD) water-distribution sysPIPE DATA BASE 

A data base was developed of the pipe inventory of the 

EBMUD water-distribution system. The System Earthquake 
A64 PERFORMANCE OF THE BUILT ENVIRONMENT 

Table 1 .-Length of pipeline in the EBMUD water-distribution system, by year of construction. 

Approximate Pipe material used (percent) 

Period total length 

(mi) Cast iron Steel PVC 

1850-99 

1900-9 

1910-19 

1920-29 

1930-39 

1940-49 

1950-59 

1960-69 

1970-79 

1980-89 

1990-92 

Unknown 

Risk Assessment (SERA) geographic-information-system 

software was used to map and analyze the buried pipelines. 

This data base uses a set of about 1,400 maps maintained by 

EBMUD that reflect the water-distribution system as of about 

1986. Each map shows the location of a buried pipe at high 

resolution (1:12,000 scale), as well as the pipe's attributes 

(diameter, material of construction, lining, coating, date of 

installation). Owing to various issues involved with the data 

base, a percentage of actual pipes in the ground were omitted 

from the analysis. The "missing" pipes constitute about 10 

percent of the total inventory, and so the results presented 

here should be viewed accordingly. 

The following observations are summarized in table 1. 

Most of the water-distribution system's cast-iron pipe was 

installed from the 1800's through 1949. 

In the 19507s, asbestos cement pipe was used for about 

half of all new pipe installation, and steel and cast-iron 

pipe for most of the rest. 

In the 1960's and 19707s, steel and asbestos-cement pipe 

were used for almost all new pipe installation. 

In the 19807s, polyvinyl chloride (PVC) pipe was introduced as a common pipe material. Asbestos-cement pipe 

installations have been phased out since the mid-1980's. 

Thus, most of EBMUD7s pipes are of three types: cast 

iron (45 percent), asbestos cement (30 percent), and steel (23 

percent); the remaining 2 percent are made of PVC and other 

materials. In general, the material types were installed during 

the following time periods: (1) cast-iron pipe from 1850 to 

1950, (2) asbestos-cement pipe from 1950 to 1985, and (3) 

steel pipe from 1950 to the present. Of a total of 3,800 mi of 

pipe, about 1,570 mi is 6-in.-diameter or smaller cast-iron, 

steel, asbestos-cement, and other types of pipe. Most (88 percent) cast-iron pipes are 4-, 6-, or 8-in. diameter, some (8 

percent) are 12-, 16-, or 20-in. diameter, and the rest are 24- 

in. diameter or larger. Most (92 percent) asbestos-cement pipes 

are 6- or 8-in. diameter, some (5 percent) are 12-in. diameter, 

and the rest are 16-in. diameter or larger. Most (65 percent) 

steel pipes are 12- to 60-in. diameter, and the rest are 6- or 8- 

in. diameter. Some pretensioned-concrete (24-, 36-, 42-, and 

54-in. diameter) and reinforced-concrete-cylinder (48- and 

54-in. diameter) pipes have also been used. Only 350 mi (less 

than 10 percent) of pipe is larger than 12-in. diameter; the 

rest is smaller. 

PIPE MATERIALS 

CAST IRON 

Cast iron is considered to be a brittle material, with a 

tensile-strain capacity of generally less than 0.5 percent. The 

strength of cast-iron pipe depends on its manufacturing process; pit-cast (sand molding) pipe is typical before 1930, and 

centrifugal-cast pipe is common thereafter. The tensile 

strength of centrifugal-cast pipe (about 28,000 lb per square 

inch [psi]) is about twice that of pit-cast pipe. Pit-cast pipe 

was manufactured mostly in 12-ft lengths, and centrifugalcast pipe typically in 18-ft lengths. 

Caulked bell-and-spigot joints are the most common. 

Both portland-cement- and lead-caulked joints were used. A 

substitute lead caulk (leadite, a sulfur-sand-salt sealing compound) was also used during World War 11. Cement-caulked 

joints are fairly rigid and of low strength, making them vulnerable to breakage or leakage under seismic loadings, 

whereas lead-caulked joints are somewhat more flexible. 

Leadite-caulked joints can weaken the pipe because of the 

expansivity of leadite at lower temperatures; this weakness 

can crack the pipe bell, as well as promote corrosion. 

ASBESTOS CEMENT 

Asbestos cement is a brittle material composed of a mixture of portland cement and asbestos fibers, with a tensile 

strength of about 2,000 psi. Standard manufactured length is 

13 ft. Pipe joints consist of short cylindrical asbestos-cement 

sleeves that fit over the ends of adjoining pipe segments; rubber rings are located in grooves to provide for a flexible watertight gasket. The joints can deflect freely as much as about 

5O, but they do not provide a rigid connection in the axial 

(that is, longitudinal) direction. 

STEEL 

Steel is a strong ductile material, with a tensile-strain 

capacity of generally more than 2 percent. Steel pipe cylinders are fabricated from such standard steels as American 

Society for Testing and Materials (ASTM) A 283, grade C 

(yield stress [Fy], 30,000 psi); ASTM A 570, grades 30 (Fy, 

30,000 psi), 33 (Fy, 33,000 psi), or 36 (Fy, 36,000 psi); ASTM 

A 36 (Fy, 36,000 psi); API 5LX, grade X-42 (Fy, 42,000 

psi); and ASTM A7 (Fy, 34,000 psi). Typically, steel pipe 
WATER-DISTRIBUTION SYSTEM A65 

has a portland-cement-mortar lining, a helical steel shell, and 

a reinforced-cement-mortar coating. More recently installed 

steel pipe (post-1960's) may have other coatings, such as 

coal tar, extruded plastic, or tape wrap. Very old steel pipes 

(pre- 1930's) were commonly unlined and uncoated. Pipesegment lengths are typically about 20, 30, or 40 ft. 

The joints in steel pipe are typically electric arc welded. 

Several different configurations were used: 

Bell-and-spigot girth joints (also called slip or lap joint) 

with either single (outside) or double (inside and outside) 

fillet welds. Single welds are the most common. This type 

of joint is most common for straight runs of pipe. 

Butt-strap girth joints with two outside fillet welds and a 

butt weld between adjoining pipes. This type of joint is 

sometimes used for larger diameter pipes at multiple joint 

bends, as well as in straight runs. The butt straps are generally larger in diameter than the main pipe. 

Butt-weld girth joints between adjoining pipe segments. 

This type of joint is typically used for multiple joint bends. 

Some very old steel pipe used riveted joint connections. 

PVC 

PVC pipe consists of extruded polyvinyl chloride plastic. PVC has a tensile strength of about 6,000 psi. Standard 

manufactured lengths are 20 ft. The joints in PVC pipe consist of a bell-and-spigot arrangement, with elastomeric gaskets integral in the bell. The joints can deflect freely for several 

degrees, but they do not provide a rigid connection in the 

axial (that is, longitudinal) direction. 

REINFORCED-CONCRETE CYLINDER 

About 15 mi of larger-diameter reinforced-concrete pipe 

was used in the EBMUD water-distribution system, mainly 

for major aqueducts built before 1930. The pipe consists of a 

thin steel cylinder (14 gage) with a reinforced-concrete layer 

on its exterior. The reinforcing has both circumferential and 

longitudinal steel bars. The pipe is cement-mortar lined. The 

total thickness of the wall is about 6 in. Pipe-segment lengths 

are 12 ft (54-in. diameter) and 16 ft (48-in. diameter). 

The joints in reinforced-concrete-cylinder pipe consist 

of a bell-and-spigot arrangement, using steel bell-and-spigot 

rings that are welded to the steel cylinder. A lead gasket is 

located between the rings; the connection area is covered with 

cement mortar. The joints do not provide a rigid connection 

between pipe segments. 

GEOLOGIC DATA 

Various geologic data were entered into the SERA software. The sources of these data include soil and landslide 

maps by Geomatrix Consultants, landslide maps by the U.S. 

Geological Survey, and corrosive-soil maps by EBMUD. The 

underlying accuracy of the Geomatrix and U.S. Geological 

Survey data is k100 ft, and of the EBMUD soil data k250 ft. 

On the bases of these data, the EBMUD service area 

was divided into seven generalized geologic soil units, with 

the following predominant soil conditions: 

Bay mud or bay fill: unconsolidated, water-saturated, dark 

plastic carbonaceous clay and silty clay, underlain by a 

few layers of sand. These areas were further subdivided 

into zones of high, or moderate to high, liquefaction susceptibility. 

Young alluvial soils: coarse, medium, and fine alluvium; 

unconsolidated, moderately sorted, permeable gravel and 

sand, silt, and clayey silt and unconsolidated, plastic silt 

and clay. These areas were further subdivided into zones 

of low or very low liquefaction susceptibility. 

Merritt sand: Pleistocene beach and dune-sand deposits; 

loose, well-sorted, fine to medium sand. Not susceptible to 

liquefaction. 

Old alluvial soils: late Pleistocene alluvium; weakly consolidated, slightly weathered, poorly sorted, irregularly 

interbedded clay, silt, sand, and gravel. Not susceptible to 

liquefaction. 

Rock: Not susceptible to liquefaction, although landslides 

can occur. 

Different soils respond differently when subjected to 

earthquake motions. Generally, peak ground velocities are 

somewhat amplified in young alluvial soils and greatly amplified in areas of bay mud or bay fill. A total of 128 mi of 

pipe was located in the worst (bay mud or bay fill) soils (fig. 

1); in addition, 99 mi of pipe is located in mapped landslide 

areas. 

CORROSIVE SOILS 

A map was prepared by EBMUD showing relative soil 

corrosivity, on the basis of nonseismic pipe-repair experience 

and judgment. Metal pipes located in high-corrosivity soils 

have higher repair rates than those located in noncorrosive 

soils. Three corrosive-soil areas were defined: (1) those associated with a high incidence of corrosion to metal pipe (that 

is, high-corrosivity soils), (2) those associated with a medium 

incidence of corrosion to metal pipe (that is, mediumcorrosivity soils), and (3) those associated with a low incidence of corrosion to metal pipe (that is, noncorrosive soils). 

PIPE PERFORMANCE-GENERALIZED 

GROUND SHAKING 

The term "ground shaking" refers to the transient soil 

deformations due to seismic-wave propagation. Ground shak- 
A66 PERFORMANCE OF THE BUILT ENVIRONMENT 

ing can cause a significant percentage of the overall pipe damage; it affects a wide area and can produce well-dispersed 

damage. Corrosion will accentuate damage, especially in segmented steel, threaded steel, and cast-iron pipes, although 

noncorroded cast-iron pipes have commonly failed as well. 

Welded-steel pipelines are damaged primarily at welds with 

poor root penetration and poor weld fusion. 

LANDSLIDES 

A landslide is a permanent displacement of soil mass, 

which can heavily damage buried pipe. Landslides cause localized severe pipe damage (that is, high pipe-damage rates 

over a small area). Landslides were mapped in many hundreds of locations in the east-bay-hill areas. More landslides 

will occur if an earthquake occurs during the rainy winter 

season than during the dry summer season. Some landslides 

are small and displace only a few inches, whereas other landslides may involve 100,000 yd3 of soil or more, over many 

feet of distance, and damage entire areas of pipelines. 

LIQUEFACTION 

Liquefaction is a phenomenon that occurs in loose, saturated, granular soils when they are subjected to several cycles 

of strong ground shaking. Sands tend to compact and settle under such conditions. If these soils are saturated as they compact 

and settle, they displace pore water upward. This upward pressure on the pore water has two effects. First, it creates a quick 

condition in which the bearing pressure of the soils is temporarily reduced. Second, if the generated pressure becomes high 

enough, material can actually be ejected from the ground to 

form characteristic sand boils on the surface. This displaced 

material, in turn, results in further settlement of the site. 

Lateral spreading is a phenomenon that can accompany 

liquefaction. At many sites, the layers of liquefiable materials are some distance below the ground surface. If the site has 

even a slight slope or is adjacent to an open cut, such as a 

depressed streambed or roadbed, gravity can cause the surficial 

soils to move downslope or toward the cut. Lateral spreading 

can be highly disruptive to buried structures and pipelines, as 

well as to structures supported on the site. 

FILL 

Figure 1 .-Pie chart showing length of pipelines (in miles) versus soil type. 
WATER-DISTRIBUTION SYSTEM A67 

Soil liquefaction can occur in certain soil units under 

certain conditions; for example, it is more likely to occur in 

the fill areas along the bay. Heavy concentrations of pipe 

breaks will occur in areas of liquefaction-induced lateral 

spreading. Similarly, liquefaction is more likely in long-duration earthquakes (more than 15 s), but would be much more 

limited in shorter duration events (3-5 s). The orientation of 

the pipe relative to the ground movement can affect the amount 

of damage. In general, ground movements that cause lateral 

(transverse) deformations of the pipe cause less damage than 

those parallel to the pipe run, because piping is relatively flexible in the transverse direction, as opposed to the axial direction, and can accommodate more transverse movement before 

damage occurs. 

Pipe-wrinkling failure occurs in thinner-walled water pipes 

at common burial depths. 

INTENSITY OF GROUND SHAKING 

AND DEFORMATION 

The stronger the intensity of ground shaking, the more 

damage an earthquake causes. Therefore, sites closer to the 

epicenter will generally sustain greater damage. Regarding 

ground failure due to liquefaction, landslides, or settlements, 

the amount of damage is related to the amount of soil deformation. 

AGE 

SETTLEMENT 

Pipe breaks can occur because of relative vertical (differential) settlements at transition zones from fill to better 

soil, and in areas of young alluvial soils susceptible to localized liquefaction. 

FAULT CROSSINGS 

Localized offsets that occur in surface-fault-rupture areas can also damage buried pipe. Damage to segmented pipes 

(for example, cast-iron pipe with caulked bell-and-spigot 

joints) will be heavy where they cross surface-rupturing 

faults. Butt-welded continuous steel pipes may be able to 

accommodate fault-crossing displacements of as much as a 

few feet. 

Butt-welded continuous steel pipelines are less prone to 

damage if they are oriented such that tensile strains result 

from the fault displacement, because tensile deformation takes 

advantage of the inherent ductility and strength of the steel, 

whereas compressive deformation results in pipe-wall wrinkling at relatively modest levels of pipe strain. 

For continuous pipelines, it is advantageous to avoid 

bends, tie-ins, and local constraints close to the fault, so as to 

allow the pipeline that crosses the fault some additional length 

over which to distribute the imposed strains resulting from 

the fault offset. 

Burial depth is also a factor at fault crossings. For shallow burial, less overburden is presented, and so less frictional 

resistance will be imposed by the soil on the pipe. The lower 

the frictional resistance, the easier the pipe will be able to 

deform, or buckle upward, in fault crossings without causing 

severe damage. 

Two failure modes occur when a pipeline is deformed in 

compression: the pipeline may buckle as a beam, or it may 

deform by local warping and wrinkling of its wall. Beam buckling can occur across fault crossings, owing either to fault 

creep or to sudden fault offset if the burial depth is shallow. 

Older pipes appear to have a higher incidence of failure 

than newer pipes. Pipe damage in the Los Angeles area due 

to the 1987 Whittier Narrows, Calif., earthquake clearly 

showed a trend of increasing pipe breaks with age of pipe 

(Wang, 1990). Note that age effects are likely to be strongly 

correlated with corrosion effects, owing to the increasing levels 

of corrosion over time. 

CORROSION 

Corrosion weakens pipe because of the effective decrease 

in material thickness, as well as creating stress concentrations. Screwed or threaded steel pipes appear to fail at a higher 

rate than other types of steel pipes. Some cast-iron pipes also 

have higher incidences of corrosion failure (Isenberg, 1978, 

1979; Isenberg and Taylor, 1984). 

Damage to corroded pipelines can significant disrupt 

water service immediately after an earthquake and lead to 

increased maintenance for a long time after the event (many 

months in Seattle; years in the 1971 San Fernando, Calif., 

earthquake). 

CONTINUOUS PIPELINES 

Continuous pipelines are pipes with rigid joints, such 

as continuous-welded steel pipelines. Continuous pipelines 

built in accordance with modern codes of practice have generally performed better in past earthquakes than those constructed with other methods (Newby, 1954). 

Experience has shown that some pipelines constructed 

before and during the early 1930's did not benefit from the 

same quality controls which prevail today. For example, the 

1933 Long Beach, Calif. earthquake caused more than 50 

breaks in high-pressure-gas pipelines in welded joints. Every 

break in large-diameter lines was discovered at welds that 

lacked proper penetration or bond with the body of the pipe. 
A68 PERFORMANCE OF THE BUILT ENVIRONMENT 

Experience has also shown that welded pipelines with 

bends, elbows, and local eccentricities will concentrate the 

deformation at these features, especially if permanent ground 

deformations induce compression strains in the pipe. Liquefaction-induced landslides during the 197 1 San Fernando, 

Calif., earthquake caused severe damage to a 49-in.-diameter water pipeline at nine bend and welded joints (O'Rourke 

and Tawfik, 1983). 

SEGMENTED PIPELINES 

A jointed pipeline consists of pipe segments that are connected by relatively flexible (or weak) connections (for example, 

a bell-and-spigot cast-iron piping system). These pipe segments 

typically can fail in several ways: excessive bending deformations of the pipe barrel, excessive rotation at a joint, or pullout 

at a joint (Singhal, 1984). Segmented pipe with somewhat rigid 

caulking, such as portland cement or lead, cannot tolerate much 

relative movement before leakage occurs. Pipes with flexible 

rubber gaskets can generally tolerate more seismic deformations, but splitting at joints has been observed under moderate 

transverse landslide movements (Buel, 1998). 

APPURTENANCES AND BRANCHES 

Experience has shown that pipeline damage tends to concentrate at such discontinuities as pipe elbows, tees, inline valves, 

reaction blocks, and service connections. Such features create 

anchorpoints (rigid locations) that promote force/stress concentrations. Locally high stresses can also occur at pipeline connections to adjacent structures (for example, tanks, buildings, 

and bridges), especially if these connections are insufficiently 

flexible to accommodate relative displacements between pipe 

and structure. This condition was reported as the reason for most 

of the damage to service connections of water-distribution piping during the 197 1 San Fernando, Calif., earthquake. 

PIPE PERFORMANCE 

IN THE EARTHQUAKE 

The 1989 Loma Prieta earthquake caused a modest level 

of damage to EBMUD's buried pipe. In this section, I review 

the damage data to discern trends in pipe performance, and 

then use this information to calibrate pipeline-fragility curves 

so as to better reflect actual pipe performance in earthquakes. 

EBMUD's repair records for about 2 weeks after the 

earthquake were reviewed, and the locations and type of repairs were tabulated. At each repair location, the estimated 

level of ground shaking due to the earthquake was calculated, 

using attenuation and soil-amplification relations specific for 

the EBMUD service area in this earthquake. This procedure 

was required because low-level instrumental readings in 

Table 2.-Repairs to EBMUD pipes due to the earthquake. 

Pipe material Number of Repair rate repairs (per 1,000 ft of pipe) 

EBMUD service areas distant from the earthquake recorded 

ground motions somewhat larger (approx 0.075 g) than would 

be predicted from the ordinary attenuation relations (approx 

0.05 g). Areas of liquefied soil and corrosive soil were compared to actual locations of damage to EBMUD's pipes. This 

information was then used to develop damage trends by using EBMUD's pipe data base, as described in detail in the 

following subsections. 

PIPE REPAIRS VERSUS PIPE TYPE 

The actual recorded earthquake repair information according to pipe type is summarized in table 2. The locations of these 

repairs are shown in figure 2, and the level of ground shaking in 

the entire EBMUD service area due to the earthquake is mapped 

in figure 3. 

The repair counts separately list the repairs made to service connections on the EBMUD side of the meter. A total of 

1 13 repairs were associated with pipe, and 22 repairs with service connections. Note that additional service leaks occurred on 

the customer's side of the meter, but these leaks are omitted in 

table 2. 

Cast-iron and steel pipe had the most repairs. The repair 

rates (number of repairs divided by length of pipe) indicate that 

asbestos-cement and plastic (PVC) pipe were the best performers and steel was the worst. This poor performance of steel pipe 

seems, at first reading, unusual because welded steel pipe is 

commonly assumed to perform better in earthquakes than castiron, asbestos-cement, or PVC pipe. As shown below, the relatively "worse" performance of steel pipe was found to reflect 

EBMUD's modem (post-1950) practice of installing only steel 

pipe in poor-soil areas; had EBMUD's practice been otherwise, 

a higher level of damage to the water-distribution system would 

likely have occurred. 

The good performance of asbestos-cement and PVC pipe 

was also reported at other sites closer to the earthquake epicenter. This performance was attributed to their rubber-gasketed 

articulated joints, which provide flexibility to withstand seismic ground movements (Pickett and others, 1991). 
WATER-DISTRIBUTION SYSTEM A69 

The distribution of actual earthquake repairs in EBMUD's 

service area is mapped in figure 2. Most repairs were west of 

the Oakland Hills, and notable concentrations are located in 

areas of deep fill and areas of liquefiable and corrosive bay 

mud or bay fill along the shores of Alameda Island and Oakland. Virtually all of the repairs shown on the south end of 

Alameda Island are for steel pipe. Steel pipe was used extensively here, and evidence was noted of modest soil movements, high-corrosivity soils, and, in some places, 

poor-quality construction that contributed to the high repair 

rate for steel pipe in this area. Still, repair rates would likely 

have been higher in this area if older cast-iron, asbestos-cement, or other weaker materials had been used. 

PIPE REPAIRS VERSUS SOIL UNIT 

The repair rates for cast-iron, asbestos-cement, and steel 

pipe according to soil unit are plotted in figure 4. (PVC pipe 

is not shown because of its small inventory.) For all pipe materials, a trend is evident for higher repair rates in bay mud or 

bay fill soils. The repair rates in bay mud or bay fill are about 

10 times higher than in other soil units. Factors that promote 

higher repair rates in bay-mud or bay-fill soils include the 

following: 

Peak ground velocities (PGV's) in bay mud or bay fill were 

higher than in other soils because of site amplification. 

Ground-shaking damage to buried pipe is proportional to peak 

ground velocity. 

Bay mud or bay fill is most susceptible to permanent ground 

deformations (PGD's), which are particularly damaging to 

pipes. In a few areas with broken pipes, damage to road pavement was noticeable, possibly because of long-term settlements in these areas, not due to liquefaction. For about five 

pipes, clear evidence was observed of soil-liquefaction movements (more than a few inches), leading to pipe damage. 

Bay mud or bay fill is generally corrosive, thereby weakening metal pipe. 

43 Steel 

Asbestos 

cement 

0 Cast Iron 

v PVC 

Figure 2.-East bay area, showing locations of pipe repairs due to earthquake. 
A70 PERFORMANCE OF THE BUILT ENVIRONMENT 

PIPE REPAIRS VERSUS PIPE DIAMETER 

For cast-iron and asbestos-cement pipe, virtually all repairs were to pipes smaller than 12-in. nominal diameter. Since 

most of the cast-iron and asbestos-cement pipes in the 

EBMUD water-distribution system are of small diameter, 

trend information on how pipe repairs were related to pipe 

diameter could not be reliably evaluated for these pipe types. 

The repair rates for steel within two different diameter 

ranges are plotted in figure 5. Note that smaller-diameter steel 

pipes had a higher repair rate, probably owing to two contributing factors. (1) Smaller diameter pipes tend to have a large 

number of bends, branches, and service laterals that produce 

virtual anchorpoints. These anchorpoints, in turn, contribute 

to damage under seismic motions. (2) Smaller-diameter pipes 

are thinner walled, making them more susceptible to corrosion. 

Note that American Water Works Association-designed 

steel pipe using single-lap arc welds faired worse from ground 

shaking that would have been forecasted by using the damage algorithms of Ballantyne and others (1990). The actual 

damage to steel pipe appeared to be more a function of weld 

quality and corrosion than whether welds were by oxyacetylene or electric arc. For example, poor-quality arc-welded 

pipes had higher repair rates than good-quality arc-welded 

pipes. Recent work by O'Rourke and Palmer (1996) corroborates this observation, suggesting that older oxyacetylenewelded pipes, with good-quality welds, may be more resistant 

to damage than has been suggested in some of the literature 

(for example, Ballantyne and others, 1990). 

PIPE REPAIRS VERSUS CORROSIVE SOILS 

The repair rates for cast-iron and steel pipe according to 

relative soil corrosivity are plotted in figure 6. In areas where 

corrosion is not too important (noncorrosive and mediumcorrosivity soils), segmented cast-iron pipe fared worse than 

welded steel pipe, as expected, whereas in areas where corrosion is important (high-corrosivity soils), welded steel pipe 

fared worse than segmented cast-iron pipe. Note that both 

PGV's and PGD's in high-corrosivity soils vary considerably. 

Downtown Oakland, which has mostly cast-iron pipe and is 

in a high-corrosivity-soil area, had only about one-third the 

level of PGV relative to the dominantly steel pipe inventory 

1 ,440,000 1,470,000 1.530,OOo 1,560,000 1,590,000 1,620.000 

Eastings, in feet 

Figure 3.-East bay area, showing peak-ground-acceleration contours due to earthquake. 
WATER-DISTRIBUTION SYSTEM A7 1 

located on Alameda Island in high-corrosivity soils. Although 

these factors tend to mask one another, the trend is that steel 

pipe is more susceptible than cast-iron pipe to corrosive-soil 

environments, all other factors being equal. 

The repair rate for steel pipe versus diameter for the 

different corrosive soils is plotted in figure 7. Steel pipe shows 

the influence of diameter in high-corrosivity soils, with larger 

repair rates for smaller-diameter pipe than for large-diameter pipe. In figure 7, both PGV's and PGD's are relatively 

constant within each category, indicating that diameter dependency is important for steel pipe in high-corrosivity soils. 

The data plotted in figures 6 and 7 indicate that corrosion effects are important for steel pipe and, to a lesser extent, for cast-iron pipe. (Note that most of the cast-iron and 

steel pipe inventory is in either medium- or low-corrosivity 

soils). Because corrosion is a continuing process, its effects 

should increase over the time since initial installation. The 

resulting repair rate according to the decade when the steel 

pipe was installed is plotted in figure 8, showing that corrosion does have a time dependency and that older steel pipe 

has a higher repair rate. 

The bulk of the damaged steel pipe in corrosive soils 

were installed in the late 1950's and early 1960's. These pipes 

are mortar lined and mortar coated, which was the most comFigure 4.-Pipe-repair rate versus soil type. 

Smaller than 12-in. 12-in. diameter and All diameters 

diameter larger 

Figure 5.-Pipe-repair rate for steel pipe, by diameter. 

Figure 6.-Pipe-repair rate for cast-iron and steel pipe versus corrosive-soil type. 

i 

mal 12- 1 in. 

in. r r 

Figure 7.-Pipe-repair rate for steel pipe, by diameter and corrosive-soil type. 

0.01 6 

Figure 8.-Pipe-repair rate for steel pipe, by decade installed. 
A72 PERFORMANCE OF THE BUILT ENVIRONMENT 

mon installation of steel pipes in that era. More recently installed steel pipe (post- 1970) use polyethylene, polypropylene, and tape-wrapped coatings. The different corrosion 

protection provided by these coatings, relative to mortar coating, was not studied. 

LOMA PRIETA EVIDENCE VERSUS 

THE DAMAGE ALGORITHMS OF 

BALLANTYNE AND OTHERS (1990) 

The pipe repair rates for the actual Loma Prieta earthquake data (digitized points) versus the pipeline-fragility 

curves of Ballantyne and others (1990) are plotted in figure 

9. Note that the work by Ballantyne and others related piperepair rates to modified Mercalli intensity (MMI), whereas 

the current work relates pipe-repair rate to PGV. Accordingly, 

an MMI of VIII was equated to a PGV of 20 inls, which 

reasonably matches the empirical building damage versus 

instrumental readings. Similarly, an MMI of IX was equated 

to a PGV of 25 inls, and so on. 

Although the Loma Prieta empirical repair rate at low 

PGV's (less than 10 inls) exceed those in Ballantyne and 

others (1990) by a large amount (factor of 10 or more), the 

low absolute values of these repair rates are not extremely 

important for overall system-analysis purposes. For example, 

by using the pipeline-fragility curves of Ballantyne and others and a PGV map similar to the peak-ground-acceleration 

map in figure 3, we would predict a total of 155 repairs in 

the EBMUD water-distribution system, versus the actual 135 

repairs (1 13 excluding service connections, 108 excluding 

service connections and PGD-attributed damage). This, on 

the whole, is a reasonable prediction; that is, given the wide 

range in empirical evidence as to pipe-damage rates, the fact 

that the prediction is within 20 to 40 percent is reasonable. 

However, the pipeline-fragility curves of Ballantyne and others are limited in that they (1) underpredict damage away 

from bay-mud or bay-fill shorelines and (2) overpredict damage in bay-mud or bay-fill shorelines. On the whole, these 

two effects tend to cancel each other, resulting in an overall 

reasonable prediction. 

PIPELINE-FRAGILITY CURVES 

The previous results summarize actual damage to 

EBMUD's pipes in the 1989 Loma Prieta earthquake and provide a known benchmark as to how EBMUD's buried pipe 

will perform in future earthquakes. From these and other 

data, we can develop empirical pipeline-fragility curves. 

Issues associated with pipeline-fragility curves include the 

following: 

Previous studies of past earthquakes have yielded repairrate data based on limited assessments. Many times large 

1989 Loma Prieta (cast iron) - Cast icon 

Â 1989 Loma Prieta (asbestos cement) - Asbestos cement 

- 

1.0000 

Empirical data from 1989 Loma PrSeta 

Damage algorithms (adjusted for PGV) 

suggested by Baltantyne and others (1 990) 

0 5 10 15 20 25 30 

Peak Ground Velocity - inches per Second 

Figure 9.-Empirical pipe repair rate (symbols) compared to damage algorithms of Ballantyne and others (1990). 
WATER-DISTRIBUTION SYSTEM A73 

areas were assigned a single MMI value, greatly ignoring 

microzonation issues. Many times, the actual mileage of 

pipe, pipe type, and level of shaking or induced PGD were 

estimated. Detailed attributes for every pipe (for example, 

age of installation, corrosive-soil conditions, type of joints) 

were commonly not tabulated. Data bases with detailed 

reviews of pipe damage are relatively limited. 

Most of the data collected to date are for earthquakes with 

relatively moderate levels of ground shaking. Most of these 

earthquakes generated ground-shaking levels in the range 

0.10-0.30 g in those areas where the most pipe damage 

was reported. At these levels of ground shaking, most pipes 

actually are not damaged: a reported repair rate of 1 per 

1,000 feet (a high repair rate) actually means that only 1 

in 83 12-ft-long pipe segments actually fails. In other 

words, about 99 percent of the pipes are undamaged. Thus, 

the empirical evidence is mostly for repair rates in the 

"tails" of the pipe's fragility distribution. 

As correctly noted by Ballantyne and others (19901, earthquake-intensity data, such as MMI's for historical earthquakes, are mostly imperfect. For example, two different 

investigators can assign different intensities to the same 

data, as evidenced by assignments of MMI's of VIII or X 

to the city of Coalinga for the 1983 Coalinga, Calif., earthquake (Hopper and others, 1984, Thiel and others, 1987). 

The same is true for other measures of seismic intensity, 

such as peak ground acceleration, velocity, and vertical or 

lateral ground movements, particularly when these measures have been inferred on the basis of MMI data, not instrumental recordings. However, the city of Oakland was 

reasonably well instrumented in the 1989 Lorna Prieta 

earthquake. The current study used 36 Oakland-area recordings (Geomatrix Consultants, 1992) in benchmarking pipeline-fragility curves to the earthquake: 24 horizontal and 12 vertical recordings (total). 

Ballantyne and others (1990) also noted that estimates of 

the pipeline exposed to the earthquake are generally approximate with respect to materials, joints, and total lengths 

of pipe. Few data are available that relate pipeline age or 

soil corrosivity to levels of damage. Repair data have often been reconstructed from the memory of workers or 

from incomplete or inaccurate data sets. One repair can 

be associated with several leaks in the same pipe barrel; 

conversely, one break can lead to several repairs. Although 

data on certain pipe materials can be complete at specific 

MMI's, they may not be complete for all pipe materials at 

all intensities. Given these weaknesses in past empirical 

pipeline-fragility data, the current study used rigorous geographic-analysis techniques to calculated the actual mileage of pipe in various soil types or ground-shaking levels, 

complete inventories of actual pipeline data by type, diameter, and so on, and a substantial number of instrumental recordings, supplemented by attenuation relations 

specific for this earthquake, and eliminated duplicated or 

nonearthquake damage records. 

Certain pipe materials and (or) joint units have only limited actual earthquake-performance data. Also, the quality of construction can vary among different countries or 

cities from which earthquake data were obtained. 

Repair data for some earthquakes represent data for limited lengths of pipe in high-intensity shaken areas; such 

data can lead to misleading damage trends, owing to smallsample-size effects. 

Repair data available in the literature commonly incorporate damage from ground shaking (wave propagation), as 

well as ground movements (for example, surface faulting, 

liquefaction, landslides). The quality of the process of disaggregating these data into components directly attributable to one type of earthquake hazard introduces additional 

uncertainty into the resulting data. 

Such issues mean that judgment must be used in applying empirical data in the development of pipeline-fragility 

curves. 

DEFINITION OF SEISMIC MICROZONATION 

HAZARD FOR PIPELINE-FRAGILITY CURVES 

The pipeline-fragility curves incorporate refinements 

relative to the damage algorithms of Ballantyne and others 

(19901, or others proposed in the literature. As noted previously, most previous studies relate damage rates to MM19s. 

One major refinement is to develop a microzonation assessment for every pipe in a water distribution or transmission 

system. This microzonation assessment provides the following information: 

Peak ground accelerations are calculated at all pipe locations. These values adjust the rock-outcrop acceleration 

to account for soil-column-amplificatio~deamplification 

effects. For the EBMUD service area, soil amplifications 

have been based on actual recordings in the Oakland area 

(1989 Loma Prieta earthquake) in bay-mud, bay-fill, and 

alluvial-soil settings. 

PGV's are calculated at all pipe locations to account for 

local soil-amplification effects. 

The extent of liquefaction occurring in susceptible areas 

is considered at each pipeline-damage location. For a given 

earthquake, liquefaction will or will not occur. If it does 

occur, calculate the extent of PGD. Similarly, calculate 

whether soil movement occurs in landslide areas and, if it 

does, the extent of PGD. 

The pipeline-fragility curves relate pipe performance 

to these three earthquake hazards as follows: (1) Groundshaking damage is related to PGV at the pipe location, (2) 

liquefaction damage is related to the amount and direction 

of lateral spreads and settlements (PGD), and (3) landslide 

damage is related to the amount of movement of the slide 

area (PGD). 

Although pipe deformations are better described in terms 

of ground strain, the geotechnical community is not currently 
A74 PERFORMANCE OF THE BUILT ENVIRONMENT 

able to make such predictions on a regional basis. However, 

using PGD as the geotechnical "predictor" when properly 

corrected to empirical data is still useful for regional estimation purposes. 

GROUND-SHAKING ALGORITHMS 

New buried-pipeline-fragility curves were developed that 

correlate pipeline-repair rates to input ground shaking (PGV) 

or ground deformations (PGD). These fragility curves were 

further described by Eidinger and others (1995). The following paragraphs highlight the methodology. 

The pipeline-fragility data plotted in figure 10 (groundshaking effect only) are based on the empirical evidence of 

the combined data set for all pipe materials from the 1965 

Puget Sound, Wash.? 1969 Santa Rosa, Calif., 1971 San 

Fernando, Calif., 1983 Coalinga, Calif., 1985 Mexico City, 

1989 Tlahuac? Mexico, and 1989 Loma Prieta, Calif., earthquakes. Each data point represents the observed repair rate 

for a class of pipe exposed to similar motions. The data presented have not been adjusted to account for magnitude-duration effects, which could explain the higher damage rates 

reported in the Mexico City lakebed area (more than 1 minute 

of shaking, three data points). 

The best-fit pipeline-fragility curve through the data in 

figure 10 is given by n=0.00032(PGV)1.98, where n is the number of repairs per 1,000 ft and PGV is in inches per second. 

This curve should be multiplied by a dimensionless constant, 

K1 (table 31, to account for various pipe materials (that is, 

total repair rate = Kin). The "quality" column in the table describes the confidence in the current empirical data (quantity 

and completeness) to support the relative Kl factors. In suggesting the "quality" of the data, "B" suggests that there is a reasonable amount of backup empirical data and study, "C" suggests 

that there are limited empirical data and study, and "D" is based 

largely on extrapolation and judgment, with only limited 

empirical data. The absence of "A" ratings suggests that there 

is still much room for future improvement in our current understanding of buried-pipeline earthquake fragility. 

The seismic hazard is defined by the expected PGV at 

the pipe-segment location. The seismic hazard depends on 

the earthquake magnitude, distance to the fault rupture, attenuation characteristics, and local soil conditions. 

LEAIUBREAK DISTRIBUTION 

On the basis of experience from other earthquakes, pipe 

damage can be classified as two types: (1) breaks typically 

associated with longitudinal cracks, splits, ruptures? and complete circumferential failures; and (2) leaks typically associated with joint failure, partial circumferential failures, and 

corrosion-related failures (pinholes and small blowouts). For 

pipe smaller than 12-in. diameter? % of the damage is asTable 3.-Values of the ground-shaking constant Kl for pipelinefragili~ curves. 

Pipe material Joint type Soils Diameter K, index 

LIQUEFACTION AND 

LANDSLIDE ALGORITHMS 

The seismic hazard is defined by the amount of PGD 

caused by either soil liquefaction or landslide. The repair 

rate depends on the magnitude of PGD sustained by a par- 
WATER-DISTRIBUTION SYSTEM A75 

ticular pipe segment. A regional geotechnical model that can 

be used to predict liquefaction and landslide PGD's was presented by Risk Management Solutions (1997). 

For liquefaction in bay mud or bay fill, PGD's include 

both lateral spreading and vertical settlement. For liquefaction in young alluvial soils, PGD's are primarily from vertical settlement. The probability of liquefaction in these soils 

depends on peak ground acceleration at the site and on earthquake magnitude. For bay mud or bay fill, the amount of 

lateral PGD depends on the peak ground acceleration, the 

distance from the shoreline, and the duration of ground shaking. The PGD direction is assumed to be toward the shoreline. For vertical settlement, the amount of settlement depends 

on the duration of ground shaking. The total PGD is taken as 

the vector sum of the lateral and vertical components. 

Landslides can occur in mapped landslide zones and 

the probability of occurrence is dependent on the season 

(winterlsummer), the peak ground acceleration at the site, 

and the duration of ground shaking. The amount of lateral 

PGD is dependent on season, the peak ground acceleration, 

and the earthquake magnitude. 

For pipe damage due to landslides, all damage is assigned to breaks. Landslides are generally associated with 

relatively large PGD7s, resulting with many breaks. 

The corresponding pipeline-fragility curve for estimating pipe repairs due to PGD's is given by n=l .03(PGD)0.53, 

where n is the repair rate per 1,000 ft of pipe and PGD is in 

inches. The fragility data for cast-iron pipe are plotted in 

figure 11. As with ground shaking, this curve should be multiplied by a constant, K2, to account for pipe materials and 

joinery (table 4). Most empirical damage data were for pipes 

located in poor-soil areas, and so a soil-corrosivity index is 

implied in the empirical data. Damage to pipelines due to 

liquefaction and landslides can be based on the same formulation; however, PGD7s due to landslides are generally much 

larger than those due to liquefaction. A refinement for soil 

corrosivity could be made but is not covered in this paper. 

With the exception of cast-iron pipe (mostly smaller diameter), the empirical evidence is very limited, as denoted by 

the quality index. The recent 1995 Kobe, Japan, earthquake 

showed much higher break rates than expected for ductileiron pipe with mechanical or tyton joints (K2-0.5), although 

pipes fitted with special slip joints capable of 2 to 3 in. of 

movement at every joint did quite well in moderate PGD's 

(K2<0.1); more study of ductile-iron and special-slip-joint 

performance is clearly mandated. 

LEAIUBREAK DISTRIBUTION 

For pipe damage due to liquefaction, half of the damage is assigned to breaks, and half to leaks. 

SIMULATION OF PIPE DAMAGE 

IN FUTURE EARTHQUAKES 

This section briefly describes the use of the pipelinefragility curves for earthquake analyses: benchmarks using 

the known Loma Prieta 1989 earthquake, and forecasts for 

future postulated scenario earthquakes. 

For the 1989 Loma Prieta earthquake, the results of 

Figure 10.-Pipe-repair-rate fragility curve versus ground shaking only. 
A76 PERFORMANCE OF THE BUILT ENVIRONMENT 

Table 4.-Values of the permanent-ground-deformation constant K2 

for pipeline fragility curves. 

Table 6.-Predicted number ofpipeline repairs to the EBMUD water-distribution system due to future large earthquakes, with or without lateral spreading in young alluvial soils. 

Pipe material Joint type Quality K2 index 

Table 5.-Predicted number ofpipeline repairs to the EBMUD water-distribution system due to a repeat of the 1989 Lorna Prieta 

earthquake. 

Number of repairs 

High Low Mean 

Figure 1 1 .-Pipe-repair-rate fragility curve versus permanent ground 

deformation. 

Number of pipe repairs Number of pipe repairs 

with lateral spreading without lateral spreading Scenario 

earthquake in young alluvial soils in young alluvial soils 

Summer Winter Summer Winter 

Hayward fault (M=7)---------- 4,700 5,500 3,250 4,025 

Hayward fault (M=6)---------- 740 1,100 720 1,080 

Calaveras fault (M=6.75) ----- 860 990 600 725 

Concord fault (M=6.5) -------- 350 420 310 380 

systemwide analyses are listed in table 5. These analyses 

predicts an average of 138 pipe repairs. This result compares 

well with the actual number of reported EBMUD repairs of 

135. 

Modifying the geotechnical model to adjust the potential for landslides in summer or winter conditions and the 

potential for lateral spreading in young alluvial soils moderately susceptible to liquefaction results in the predictions 

listed in table 6. These results show that variances in the 

geotechnical model assumptions can lead to significant differences in the amount of predicted pipe damage. 

A comparison of the results from analyses using the 

damage algorithms of Ballantyne and others (1990) with 

those using the updated pipeline-fragility curves indicates: 

The updated pipeline-fragility curves predict somewhat 

fewer repairs. The repair range predicted for the 1989 Loma 

Prieta earthquake is from 108 to 161, whereas the repair 

range predicted using the damage algorithms of Ballantyne 

and others (1990) is from 135 to 179. 

The updated pipeline-fragility curves predict the distribution of repairs throughout the EBMUD service area better 

than the dispersion from using the damage algorithms of 

Ballantyne and others (1990)7 which predict too few 

ground-shaking-related repairs and a much tighter geographic distribution of pipe repairs relative to what was 

actually observed in the 1989 Loma Prieta earthquake. 

DAMAGE TO 

OTHER EBMUD FACILITIES 

Included in EBMUD's water-distribution system are 6 

water-treatment plants, 175 treated-water reservoirs (mostly 

tanks)7 125 pumping plants7 and 23 office, warehouse7 and 

maintenance buildings. As of 198g7 there were 284 individual 

facilities (some sites include 2 or more facilities). For the most 

part7 damage to these 284 facilities was either none or slight. 

This observation is attributed to the following factors: 

Ground-shaking levels at the 284 facilities were modest7 

generally ranging from 0.04 to 0.10 g (see fig. 3). Along 

the San Francisco Bay shoreline, where bay-mud deposits 
WATER-DISTRIBUTION SYSTEM A77 

amplified motions to more than 0.20 g, EBMUD has no 

above-ground water-system facilities. 

EBMUD has had longstanding practices to design its facilities for some level of earthquake motions. Only six facilities predate 1930, when the first seismic standards were 

used; however, each of these six facilities has since been 

seismically retrofitted to at least a minimum seismic capability. 

About half of the 284 facilities were built by using an 

equivalent base-shear value of either 10 or 13 percent of 

gravity (those built from 1935 to 1973). 

Beginning in 1973, EBMUD instituted self-imposed seismic standards that generally exceed the minimum seismic 

standards of the Uniform Building Code (UBC). 

Beginning in 1985, EBMUD adopted many provisions of 

the Applied Technology Council (ATC)'s specification ATC 

3-06, as well as modern AWWA and API tank-design considerations. Pseudo-site-specific ground motions were used 

for all facilities within 6 mi (10 km) of active faults. 

Beginning in 1995, EBMUD updated its seismic standards 

to reflect current understanding of site specific ground 

motions, ductility considerations, and importance and redundancy issues. Before application of importance factors 

(I= 1, 1 -25, or 1.5), site-specific PGA's can reach as high as 

0.6 g for sites immediately adjacent to active faults. 

Even so, some level of seismic damage did occur at a 

few facilities. Not all of this damage was immediately identified after the earthquake. The following paragraphs summarize the damage. 

Ofice building.-Built to the 1988 UBC, this building 

is located in downtown Oakland on a firm-soil site. Probable 

ground motions at this site were in the range 0.05-0.10 g. 

The building is a moment-resistant steel-frame structure, designed to 2~0.4 g and 1=1 .O, following the UBC code. At the 

time of the earthquake, the structure was still under construction. The steel frame was essentially complete. Some external 

cladding (concrete panels) were dislodged in the earthquake. 

Open-cut lined reservoir.-Built in 1956, this reservoir 

has storage capacity of 50 million gal. The reservoir is built 

into the ground. A precast concrete roof system covers the 

reservoir. Interior inspections in 1992 revealed that about 1 

to 2 percent of the concrete panel to column connections had 

been dislodged. In a few locations, steel bars were exposed. 

From the outside, damage to the roof would not be apparent 

to the casual observer. Most likely, this site underwent ground 

motions in the range 0.10-0.15 g. The original design basis 

for the roof was likely an equivalent static load of 0.10 times 

the weight of the roof. The damage was considered severe 

enough to preclude people from walking on the root however, the reservoir remains in service (through 1996). Currently, there are conceptual plans to retrofit the roof, but high 

cost and perceived modest benefit of such retrofit may preclude or postpone its implementation. 

Steel tank.-The tank is built on grade. Most likely, this 

site underwent ground motions in the range 0.05-0.10 g. The 

steel roof beams were severely twisted. The damage was ascribed to wave sloshing forces from the earthquake (but could 

have predated it?). From the age of this tank, it is unclear 

whether the roof system had been designed to withstand any 

hydrodynamic forces. (The main tank and its anchorage system were designed for earthquake forces.) 

Pump station.-The building for one pump station in 

the Berkeley area (PGA, 0.05-0.10 g) was reported as being 

moderately damaged. The damage to the structure did not 

disrupt operation of the pumping plant, because the electrical 

and mechanical equipment were undamaged. 

Power outages.-The earthquake caused widespread 

power outages in the EBMUD system. Generally speaking, 

the duration of these outages were under 24 hours. Due to the 

limited damage to buried pipes (except in shoreline areas), 

water-leak rates were modest, and no customers lost water 

supply attributable to loss of electric power. 

Customer outages.-Less than 2 percent of EBMUD's 

440,000 customers (one customer = one billing account) lost 

water service as a result of the earthquake. Most of those customers that lost water service were located in areas with broken water pipes. Water service to these customers was restored 

as soon as pipe breaks were repaired (within 3 days). 

Water losses.-One large pipe break (16-in.-diameter 

cast-iron pipe) was not located immediately after the earthquake. EBMUD7s real-time data-acquisition system showed 

an unusual drawdown of water from a 150-million-gal reservoir. The earthquake occurred in the early evening, but the 

significance of the leak rate was not noted until well after 

dark. The pipeline break was found several hours after the 

earthquake, by tracing the pipelines leading from the reservoir, using flashlights. This pipeline break had probably not 

been identified earlier because the break location was in a 

field location with few, if any, people passing by. Another 

large raw-water-pipeline leak (60-in. diameter) occurred, forcing the closure of one of the water treatment plants. The area 

served by that treatment plant was also served by a second 

treatment plant, and so this pipeline break caused no customer outages. Postearthquake investigations of this 60-in.- 

diameter pipeline identified numerous poor welds (shop welds, 

not field welds) along the helical coil; the pipeline has since 

been entirely replaced. 

RECOMMENDATIONS 

The pipeline-fragility curves for buried pipelines, ca. 

1996, still have room for improvement (see "quality index," 

tables 3,4). Rapid postearthquake field investigations are insufficient to add precision to these curves. The analysis of 

pipe vulnerability due to soil deformation (liquefaction and 

landslides) for the earthquake-affected area is essential if we 

are to learn from earthquakes what factors are most critical to 

causing buried-pipe failures. The use of geographic-analysis 

techniques should play a key role in this evaluation. This type 
A78 PERFORMANCE OF THE BUILT ENVIRONMENT 

of research is needed to develop more reliable designs for 

future pipeline installations for water utilities. 

ACKNOWLEDGMENTS 

This research was made possible by the collaboration of 

several engineers and scientists, including Bruce Maison, Robert Lau, and Joseph Young of the East Bay Municipal Utility 

District and Maury Power, John Egan, and Chuck Taylor of 

Geomatrix Consultants. Their efforts are greatly appreciated. 

REFERENCES CITED 

Ballantyne, D.B., Berg, E., Kennedy, J., Reneau, R., and Wu, D., 

1990, Earthquake loss estimation modeling for the Seattle water system: report to U.S. Geological Survey under Grant 14- 

08-0001-G1526. 

Buel, B., 1998, Water supply emergency after action report: 

McKinleyville Community Services District. 

Eidinger, J.M., Maison, B., Lee, D., and Lau, B., 1995, East Bay 

Municipal Utility District water distribution damage in 1989 

Loma Prieta earthquake, in U.S. Conference on Lifeline Earthquake Engineering, 4th, San Francisco, 1995, Proceedings: 

American Society of Civil Engineers, Technical Council on 

Lifeline Earthquake Engineering Monograph 6. 

Geomatrix Consultants, 1992, Strong motion recording stations, 

Loma Prieta earthquake, from assessment of earthquake-related geological/geotechnical hazards; Water System Seismic 

Evaluation Program, phase I: East Bay Municipal Utility District Report 1990H. 

Hopper, M.G., Thenhaus, P.C., Barnhard, L.M., and Algermissen, 

S.T., 1983, Damage survey in Coalinga, California, for the earthquake of May 2, 1983, in Bennett, J.H., and Sherburne, R.W., 

eds., The 1983 Coalinga, California earthquakes: California 

Division of Mines and Geology Special Publication 66, p. 5-8. 

Isenberg, J., 1978, Seismic performance of underground water pipelines in the southeast San Fernando Valley in the 1971 San 

Fernando earthquake: New York, Weidlinger Associates, 

Grand Report 8. 

1979, Role of corrosion in water pipeline performance in 

three U.S. earthquakes: U.S. National Conference on Earthquake Engineering, 2d, Stanford, Calif., Proceedings. 

Isenberg, J., and Taylor, C.E., 1984, Performance of water and sewer 

lifelines in the May 2, 1983, Coalinga, California earthquake, 

in Lifeline earthquake engineering, performance, design and 

construction: New York, American Society of Civil Engineers. 

National Board of Fire Underwriters, 1933, Report on the City of 

Oakland, California: Report 134. 

Newby, A.B., 1954, Pipelines ride the shockwaves: San Francisco, 

Pacific Coast Gas Association Proceedings 45. 

O'Rourke, T.D., and Tawfik, M.S., 1983, Effects of lateral spreading on buried pipelines during the 1971 San Fernando earthquake, in Earthquake behavior and safety of oil and gas storage facilities, buried pipelines and equipment (PVP volume 

77): New York, American Society of Mechanical Engineers. 

O'Rourke, T.D., and Palmer, M.C., 1996, Earthquake performance 

of gas transmission pipelines: Earthquake Spectra, v. 12, no. 

3, p. 493-527. 

Pickett, M.A., Laverty, G.L., Abu-Yasein, O.A., and Lay, C., 199 1, 

Lessons learned from the Loma Prieta earthquake: American 

Water Works Association Journal. 

Risk Management Solutions, 1997, Development of a standardized earthquake loss estimation methodology: report prepared 

for the National Institute of Building Sciences. 

Singhal, A.C., 1984, Nonlinear behavior of ductile iron pipeline 

joints, Journal of Technical Topics in Civil Engineering, v. 

110, no. 1, p. 29-37. 

Thiel, C.C., Jr., and Zsutty, T.C., 1987, Earthquake parameters and 

damage statistics: San Francisco, Forrell/Elsessor Engineers. 

Wang, L., 1990, A new look into the performance of water pipeline systems from 1987 Whittier Narrows, California earthquake: Norfolk, Va., Old Dominion University, Department 

of Civil Engineering Report ODU LEE-05. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

WATER- AND WASTEWATER-TREATMENT PLANTS 

By William F. Heubach, Summit Technology Consulting Engineers; 

and 

Donald B . B allantyne, EQE International 

CONTENTS 

Page 

A79 

79 

79 

8 1 

82 

83 

83 

83 

84 

84 

85 

85 

85 

ABSTRACT 

During the earthquake? water- and wastewater-treatmentplant tank elements were affected. A damage inventory was 

made? and earthquake loads were estimated for damaged and 

undamaged water- and wastewater-tank elements, including 

baffles, submerged piping and equipment? and floating digester covers. The comparison of relative degrees of damage 

and effect on plant operations has resulted in generalized 

guidelines that can be used to design more resilient systems 

which will reduce the impact of equipment failure on plant 

operations. 

cisco Bay region, significant damage to tank elements was 

reported as far away from the epicenter as the Sacramento 

Regional Wastewater Treatment Plant, approximately 100 mi 

from the epicenter. The locations of some of the treatment 

plants addressed in this paper are shown in figure 1. 

Most water- and wastewater-treatment-plant tanks are 

reinforced- and (or) prestressed-concrete structures. An inventory of the earthquake damage to water- and wastewatertreatment plants in the San Francisco Bay region revealed 

that basin and tank structures were not significantly damaged. 

Steel water-storage tanks built to American Water Works Association (AWWA) seismic specification D 100 also performed 

well. Generally? tanks that did sustain structural damage had 

not been constructed to AWA seismic specification D 100. 

Submerged and attached equipment in tanks? including 

floating tank roofs? were significantly damaged at some water- and wastewater-treatment plants. Repair costs ranged as 

high as $1 -7 million at one treatment plant. 

In general? earthquake-load design standards do not exist for elements submerged and (or) attached to water- and 

wastewater-treatment-plant elements. Earthquake-induced 

loads are generally not considered when tank equipment is 

designed for treatment plants. Therefore? the level of earthquake damage to some San Francisco Bay region treatment 

plants is not surprising. In addition to summarizing the earthquake damage to various water- and wastewater-treatmentplant tank elements, this paper presents loss-mitigation 

recommendations. 

INTRODUCTION 

DIGESTERS 

The 1989 Loma Prieta earthquake was felt throughout 

central California and as far away as Los Angeles? Eureka? 

and western Nevada. Most metropolitan regions in the San 

Francisco Bay region were assigned a modified Mercalli intensity (MMI) of VI or VII; however? some areas? such as the 

Marina District of San Francisco and the area around the 

Cypress Street viaduct in Oakland, were assigned an MMI of 

IX. The epicentral area in the Santa Cruz Mountains was generally assigned an MMI of VII (Stover and others? 1990). 

Although damage to water- and wastewater-treatmentplant tank elements was generally limited to the San FranDigesters are tanklike structures used in some wastewater-treatment processes. Raw sludge obtained from the settling of wastewater solids is pumped into digesters? where 

the volume of the solids is reduced by anaerobic bacterial 

digestion and gravity thickening. The digestion process can 

be accomplished by either a single digester tank or by a series 

of two tanks in which the raw sludge is decomposed by bacteria 

in the first tank and gravity-thickened in the second tank. 

Many digester tanks use floating covers designed to move 

upward or downward when sludge is added or withdrawn. 
PERFORMANCE OF THE BUILT ENVIRONMENT 

EXPLANATION * Epicenter 

8 Felt at intensity 8 

Figure 1 .-San Francisco Bay region, showing locations of water- and wastewater-treatment plants studied and areas of modified 

Mercalli intensity (roman numerals). EBMUD, East Bay Municipal Utility District. From Stover and others (1990). 
WATER- AND WASTEWATER-TREATMENT PLANTS A8 1 

Piping is used to transfer undigested sludge into the digester 

and to withdraw digested sludge? separated liquids (supernatant)? and methane gas. Depending on the type of digester? 

heating equipment and mixing equipment? such as gas-injection tubing, may also be installed in the digester. A typical 

digester is shown in figure 2. 

DIGESTER DAMAGE 

The basic digester-tank structural systems in wastewater-treatment plants affected by the earthquake performed very 

well. Generally? damage to nonstructural tank elements was 

due to sloshing digester liquid contents, The sloshing liquids 

caused floating digester roofs to rock up and down. Cover 

Figure 2.-Cross section of typical digester with floating cover. 

FLOATING COVER DETAIL 5ECTlON 

Figure 3.-Digester-roof roller-guide assembly. 

guides? designed to permit only uniform vertical movement 

of the digester roofs? were subjected to large horizontal forces 

as they resisted the horizontal component of the cover's displacement. Additionally? liquid turbulence? unsymmetric roof 

mass properties and (or) unsymmetric resistance of cover 

guides were the likely reasons why some covers rotated. Damage to digester elements? such as floating covers and cover 

guides? occurred at several treatment plants. 

The area of the East Bay Municipal Utility District 

(EBMUD) wastewater-treatment plant in Oakland (near the 

Cypress Street viaduct) was assigned an MMI of VII. Most 

of the digesters at the plant use floating covers. Cover rotation is restricted by placing some of the rollers in slots (for 

example? fig. 3)? using clips to travel in slots? or channels to 

guide clips attached to the digester covers. 

Extensive damage occurred in the digester's cover-guide 

and antirotation assemblies. One digester cover rotated 4 ft. 

Typically7 failure of the guide rollers occurred at the roller1 

digester-cover interface. Rollerldigester roof connections 

failed because of shearing of bolts and welds in the connection assemblies and (or) bending of the attachment brackets. 

Some of the tracks used to prevent rotation were bent by either rollers or guide clips. 

No damage to digester flexible hoses or piping was reported. However? the fluids in one digester did slosh over the 

digester wall. Furthermore? corbels used to support access 

bridges between the digesters were damaged. 

The MMI at the San Jose-Santa Clara Wastewater Treatment Plant? located near the southeast tip of San Francisco 

Bay7 was likely V or VI. The floating digester covers at the 

plant are guided by cylindrical rollers attached to the top of 

the digester roofs by steel-clip assemblies. The rollers bear 

directly against the inside of the digesters' concrete walls. 

Rotational restraint is provided by cables that are connected 

between the roller attachments and metal clips bolted to the 

digester walls. 

A total of 12 digesters rotated 6 to 8 in. counterclockwise. As was the case at the EBMUD wastewater-treatment 

plant in Oakland, roller-guide connections failed. On two digesters? rocking and rotation of the digester covers caused 

deflection of the gas-collection line that runs from the center 

of the digester covers and down the outside of the digesters. 

Eventually7 the lateral pipe restraints connected to the digester 

walls failed. Differential movements between the rigid horizontal piping connected to the digester cover and the rigid 

vertical piping running down the digester wall caused the flexible rubber hosing between the two rigid sections to tear at 

the flange connection to the rigid vertical pipe. These two 

digesters had to be shut down until they could be repaired. 

Three different types of digesters are used at the Sacramento Regional Wastewater Treatment Plant. The first type 

is about 90 ft in diameter and uses a high dome-shaped floating cover. The guide and antirotation system is similar to that 

at the EBMUD wastewater-treatment plant in Oakland. 
PERFORMANCE OF THE BUILT ENVIRONMENT 

The second type of digester used at the Sacramento Regional Wastewater Treatment Plant is 100 ft in diameter and 

has a flat7 floating cover. Only one digester of this type is 

used at the plant? for sludge blending and storage. Guidance 

of the digester cover is accomplished with rollers and corkscrew-patterned curved tracks on the inner digester walls. 

The rollers and tracks are oriented so that as the digester 

cover rises and falls? the digester cover rotates. The corkscrew-patterned tracks force the digester roof to remain level 

as it rises and falls. 

The third type of digester used at the Sacramento Regional Wastewater Treatment Plant has guide and antirotation 

systems that are similar to those at EBMUD7s wastewatertreatment plant in Oakland. The digesters are 110 ft in diameter. The covers are guided by rollers around the cover 

perimeter. Cover rotation is resisted by shaped plates that travel 

in vertical tracks bolted to the digester walls. 

The Sacramento region was assigned an MMI of IV or 

V. Of the three different types of digesters used at the Sacramento Regional Wastewater Treatment Plant? only the third 

type of digester was damaged. As was the case at EBMUD7s 

wastewater-treatment plant in Oakland? the rollerlclip attachments to the digester covers failed when the bolts and roller 

brackets were sheared. 

Unlike the digesters at EBMUD7s wastewater-treatment 

plant in Oakland? digesters of the third type used at the Sacramento Regional Wastewater Treatment Plant mix their contents by gas injection. Piping? which is attached to the interior 

of the digester covers and fits into stationary draft tubes attached to the digester floors? was bent. The stationary draft 

tubes and draft-tube supports7 along with the digester floor 

slab7 did not appear to be damaged. Additionally7 the corbels7 

which support the digester covers when the digesters are down 

for maintenance, were damaged. Corbel damage appeared to 

be restricted to spalling. Pounding of the corbels and covers 

also resulted in bending of the digester-cover skirt plates. 

The earthquake damage to the digesters at other wastewater-treatment plants in the San Francisco Bay region was 

similar to that at the San Jose-Santa Clara? EBMUD? and Sacramento wastewater-treatment plants. Much of the digester 

damage could be easily repaired. For example? the damaged 

digesters at EBMUD7s wastewater-treatment plant in Oakland continued to operate normally; however? more severe 

sloshing could have resulted in much more severe damage 

that would have resulted in loss of digester functionality or 

even release of methane gas. The earthquake damage to digesters at wastewater-treatment plants in the San Francisco 

Bay region is summarized in table 1. 

NEW-DIGESTER LOSS-MITIGATION 

RECOMMENDATIONS 

Table 1 and the previous discussion show that earthquake damage to digester systems in the San Francisco Bay 

Table 1 .-Earthquake damage to digesters at wastewater-treatment 

plants in the Sun Francisco Bay region. 

[EBMUD, East Bay Municipal Utility District; MMI, modified Mercalli intensity] 

T~atment plant Digester damage &timated 

(fig. 1) MMI 

San Leandro------------------ Sloshing broke glass veiwing ports. VI-VII 

Sunnyvale .................... Sludge sloshed over sides, and VI-VII 

alignment guides were damaged. 

Watsonville------------------- Existing concrete cracks in fixed VII-VIII 

covers opened up farther. 

Sacramento------------------- Alignment guides were damaged, IV-V 

and corbels were damaged when 

they pounded against one another. 

San Jose-Santa Clara-------- Alignment guides failed. A gas- V-VI 

collection line was severed by cover rocking. 

EBMUD ...................... Alignment guides were extensively VII 

damaged. Corbels were damaged by 

pounding. 

region resulted from three basic mechanisms. Most digester 

damage resulted from the rocking (tilting) and (or) rotation 

of floating covers. The third cause of digester damage was 

caused by insufficient flexibility to accommodate differential movements between digester tanks and piping. Means of 

providing sufficient flexibility between digester tanks and 

appurtenances were documented by Hakala (1980). 

The successful earthquake performance of digester 

fixed-position (nonfloating) covers at the Union Sanitary 

District? San Leandro? and Watsonville wastewater-treatment 

plants (fig. 1) suggests that one way to avoid cover rocking 

and rotation-induced damage is to use fixed covers in future 

digester designs. Sufficient freeboard to allow for sloshing 

of digester contents would have to be provided? or the cover 

would have to be strong enough to resist the sloshing forces. 

Fixed covers would be subjected to large forces if sloshing fluids were allowed to impact digester covers. A design 

would have to be developed to reduce sloshing loading. One 

alternative design might be to install baffles around the tank 

interior walls so as to deflect sloshing liquids and reduce the 

sloshing forces on the roof. Alternatively? adequate freeboard 

could be provided by using the procedure outlined by Veletsos 

(American Society of Civil Engineers? 1984) to estimate the 

sloshing height. Because digester tanks are commonly situated on soft soils that tend to amplify longer-period motions? 

the calculations of special accelerations to be used in Veletsos7 

procedure should reflect the more dominant long-period 

ground motions. Otherwise? use of Veletsos7 procedure may 

underestimate sloshing amplitudes. 

One significant drawback of fixed-cover digesters is that 

digester operations are adversely affected by using fixed instead of floating covers. When floating-cover digesters are 

required, details can be designed that either reduce damage 

susceptibility or facilitate repair in the event that damage 

does occur. 

The digesters with high-domed floating covers used at 

the Sacramento Regional Wastewater Treatment Plant performed better than other digesters at the plant with similar 
WATER- AND WASTEWATER-TREATMENT PLANTS A83 

cover-guide and antirotation systems. The most probable explanation for this better earthquake performance is that less 

area of the high-domed floating digester cover was impacted 

by sloshing fluid. Furthermore, those areas that were impacted were subjected to much smaller sloshing-induced 

forces than corresponding areas of the flat floating digester 

covers. Therefore, the high-domed digester-cover guides and 

antirotation-system components were not subjected to the 

high levels of force that were applied to the flat-cover digester guides and antirotation-system components. 

In addition to preventing damage to components of the 

cover guides and antirotation system, the high-domed floating digester covers limited rocking and rotation of the covers, and so pounding between the corbels and cover skirt did 

not occur. 

The flat, floating digester cover with curved guide tracks 

at the Sacramento Regional Wastewater Treatment Plant also 

performed well. Because the tracks were curved, rocking of 

the cover was prevented. Still, the cover and guide systems 

were subjected to sloshing-induced forces. If the sloshing 

loads rotated the cover in the same direction permitted by 

the guide tracks, the cover and guide systems would be subjected to smaller forces than if rotations were not permitted. 

Larger forces would occur if the sloshing loads rotated the 

cover against its natural rotating direction. Therefore, although a rotating flat cover would not rock, the cover and 

guide systems could still be subjected to potentially large 

sloshing-induced forces. 

EXISTING-DIGESTER LOSS-MITIGATION 

RECOMMENDATIONS 

Although the damage to digesters at wastewater-treatment plants in the San Francisco Bay region was widespread, 

the only known digesters that had to be immediately shut 

down were the two with broken gas-collection lines at the 

San Jose-Santa Clara Wastewater Treatment Plant. Because 

this plant had sufficient excess capacity, plant operations were 

not significantly affected. Other digester damage affected 

digester performance to varying degrees. 

For floating-cover digesters without attachments that 

could be damaged by rocking and rotational movements, it 

is probably not economical to retrofit the digesters by attempting to strengthen cover guides, antirotation systems, 

and floating covers. Repair costs in the event of an earthquake would most likely be less than the cost of retrofitting. 

If cover rocking and rotation could damage the attached piping and equipment, the potential economic and operationalcapability losses from an earthquake should be weighed 

against the cost of providing sufficient flexibility to attached 

piping and equipment, or of retrofitting digester covers. 

Should a cost-benefit analysis indicate that retrofitting 

is feasible, one potential measure would be to use cover 

guides similar to the corkscrew-patterned tracks used on digesters at the Sacramento Regional Wastewater Treatment 

Plant. Depending on the digester, a curved-track guide system could be installed either above or below the digester 

cover. The digester cover may need to be strengthened if a 

curved-track system is chosen. 

On some digesters, such as those with gas-injection tubing at the Sacramento Regional Wastewater Treatment Plant, 

cover rotation cannot be permitted. If the cover rotation must 

be zero, fixing the position of the digester covers may be a 

feasible means of mitigating earthquake damage. 

WATER-TREATMENT-PLANT 

TANK ELEMENTS 

Tanks for water-treatment clarification are typically used 

for mixing of chemical coagulants with the influent, flocculation, and sedimentation of particulate matter. Filtration is 

used after sedimentation to remove nonsettlable floe. 

Coagulation and sedimentation can be done in compartmental tanks or in a single compartmented tank. In both types 

of tank, earthquake motions can cause sloshing of basin or 

tank contents. This sloshing stresses tank elements, including submerged equipment and baffles. 

RINCONADA WATER TREATMENT PLANT 

TANK-ELEMENT DAMAGE 

The Rinconada Water Treatment Plant, located about 

17 mi from the earthquake epicenter and only 5 mi from the 

San Andreas fault (fig. I), sustained the most damage of all 

water- and wastewater-treatment plants in the San Francisco 

Bay region. Three clarifiers were badly damaged by sloshing and wave action. A fourth clarifier, which was empty at 

the time of the earthquake, was undamaged. Repair costs to 

the three clarifiers were estimated at $1.7 million. 

Section and plan views of the affected clarifiers are 

shown in figure 4. Each clarifier has 177-ft-square sides and 

22-ft-high concrete walls. Major equipment items include 

an EIMCO center-feed flocculator, a cone-shaped reaction 

well, a rotating flocculator, radial launders, and a rotating 

sludge scraper. The equipment-support designs did not consider resistance to earthquake-induced lateral forces. 

Vertical structural support of the clarifier is provided by 

a 39-in.-diameter center steel column, fabricated from rolled 

steel plate, that is cantilevered from the center of the clarifier 

floor. The steel column either directly or indirectly supports 

the various rotating and fixed mechanisms. 

Wave heights as high as 6 ft above the water surface 

were observed. Once the water within the clarifier began to 

slosh, raw- and settled-water pipe connections between the 

steel column and reaction well separated. At this point, the 

reaction well was supported vertically only by four horizontal steel beams that cross at the top of the steel column. As 
A84 PERFORMANCE OF THE BUILT ENVIRONMENT 

the reaction well rocked with the sloshing fluids, the reaction-well-support system rotated and damaged other attached 

equipment. About half of the radial launders were torn away 

from and pounded the clarifier walls. Some of the damaged 

launders fell to the bottom of the clarifier and jammed the 

rotating sludge scrapers. 

After the earthquake, the three damaged clarifiers were 

unable to perform their design functions. Water demands were 

met by bringing the empty, undamaged clarifier on line and 

using one of the damaged clarifiers as a static chemical mixer 

for direct filtration. 

At the time of the earthquake, EIMCO, the gear manufacturer, was casting gears similar to those used at the 

Rinconada Water Treatment Plant for another project. EIMCO 

was able to supply replacement parts in 3 weeks instead of 

the normal 9-month time period by adjusting its shipping 

schedules. However, repair still required 6% to 7 months. 

DAMAGE TO OTHER TANK ELEMENTS 

Clarifiers at other water- and wastewater-treatment plants 

sustained various amounts of equipment and baffle damage. 

The most severe damage occurred at the Rinconada Water 

Treatment Plant (fig. 1). At the Alvarado, Palo Alto, and South 

Bayside wastewater-treatment plants, damaged baffles fell to 

REACTION WLL 

5LUD6E SCRAPERS A 

SECTION 

BRIDGELAUNDER (lYP) 

WLLECTOR 

DRIVE 

TURBINE DRIVE 

PLAN 

INFLUENT, EFFLUENT 

LINES BELOPI BRIDGE 

Figure 4.-Clarifier design at the Rinconada Water Treatment Plant. 

the bottom of the clarifiers and caused the sludge scrapers to 

jam. At the Tracy water-treatment plant, a central column was 

deflected and jammed the scraper against the clarifier walls. 

Although the Tracy plant was shut down, water demands were 

satisfied by wells typically used only during the peak summer months. The earthquake damage to clarifiers at waterand wastewater-treatment plants in the San Francisco Bay 

region is summarized in table 2. 

The treatment-plant tank structures typically were not 

heavily damaged. The concrete basins leaked at the construction joints at a low-sand-filter treatment plant in Watsonville. 

When a construction joint between the primary sedimentation tanks and effluent channel cracked at the Santa Cruz 

Wastewater Treatment Plant, the leakage undermined the tank 

structure. Settlement of clarifier tanks occurred at both the 

Millbrae and Treasure Island sewage-treatment facilities. 

LOSS-MITIGATION RECOMMENDATIONS FOR 

TANK ELEMENTS 

Clearly, clarifier-equipment and baffle design should 

consider earthquake-induced sloshing loads. When dynamic 

forces are calculated for submerged equipment, the effects of 

the surrounding water must be considered. The effective mass, 

me, can be approximated as (for example, Chopra and Liaw, 

1976; Haroun and Bashardoust, 1986) 

where rn is the mass of the submerged object, rn is the mass 

of the fluid surrounded by the submerged object, and m is 

the added mass due to interaction with the surrounding fluid. 

For a solid cylinder, the maximum effective mass equals the 

mass of the cylinder plus the mass of a volume of fluid that 

equals the volume of the cylinder (Haroun and Bashardoust, 

1986). 

The total force on the structural system must also include the viscous-drag force, q: 

where C is the drag coefficient, p is the fluid density, A is 

the project area, u is the fluid velocity, and iJ is the object's 

velocity. 

The equation of motion can then be written as 

mv + cV + kv = 

C.,p,A I u - iJ I (u - +)I2 - [me, - 2(u/~)rn~]~, (3) 

where c is the damping, k is the stiffness, G is the ground 

acceleration, and m is the fluid mass displaced by the submerged object's enclosed volume. 

Design-spectrum techniques can be used to estimate the 

sloshing forces from the equation of motion. These sloshing 

forces may be so large for some submerged structures that it 

A86 PERFORMANCE OF THE BUILT ENVIRONMENT 

Earthquake Engineering Research with Emphasis on Lifeline 

Systems. 

Earl and Wright Consulting Engineers, 1989, Rinconada water treatment plant flocculation tank equipment response to seismic 

loadings. 

Hakala, W., ed., 1980, Earthquake design criteria for water supply 

and wastewater systems: EQSI report prepared for U.S. National Science Foundation. 

Haroun, M.A., and Bashardoust, F., 1986, Vibrations of submerged 

solids in a vibrating container: American Society of Civil Engineers Conference on Dynamic Response of Structures, 3d, 

Proceedings. 

Stover, C.W., Reagor, B.G., Baldwin, F.W., and Brewer, L.R., 1990, 

Preliminary isoseismal map for the Santa Cruz (Loma Prieta), 

California, earthquake of October 18, 1989 UTC: U.S. Geological Survey Open-File Report 90-18,24 p. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

LESSONS LEARNED BY WATER AND WASTEWATER UTILITIES 

CONTENTS 

By Mark Pickett, University of Toledo; 

and 

Gordon L. Laverty, Laverty Associates 

Abstract----------------------------------------------------------------------- 

Introduction ................................................................... 

Organization------------------------------------------------------------------ 

Energy sources--------------------------------------------------------------- 

Portable equipment---------------------------------------------------------- 

Communications and public information ................................ 

Inventory--------------------------------------------------------------------- 

Emergency-response plan .................................................. 

Mutual-aid planning ......................................................... 

Training----------------------------------------------------------------------- 

Long-term recovery planning .............................................. 

Vulnerability assessment and mitigation of hazards-------------------- 

Examples of water and wastewater lines vulnerable to earthquake darnageTypes of pipe in water-distribution systems-------------------------- 

Location of water-distribution lines ................................... 

Page 

ABSTRACT 

This paper states some of the lessons that water and 

wastewater utilities learned during the earthquake, those 

learned during the response period immediately after the 

earthquake, and those determined by analyses many months 

later. These lessons learned are grouped into two major categories: (1) utility operations, including preparedness and 

response; and (2) engineering design and facility performance. Although the implementation of these lessons will 

be costly, the utilities that implement them will have made a 

significant investment in earthquake-disaster mitigation. 

INTRODUCTION 

In the aftermath of the 1989 Loma Prieta earthquake, 

the Technical Council on Lifeline Earthquake Engineering 

of the American Society of Civil Engineers organized several damage-reconnaissance teams to inspect water- and wastewater-treatment plants and to interview their personnel in 

the Oakland-San Francisco-Santa Cruz-Hollister area. We 

were members of one of these teams. This paper reflects the 

lessons learned during the earthquake, those learned during 

the response period immediately after the earthquake, and 

those determined by analyses many months later. The lessons that can be learned from the earthquake are grouped 

into two major categories: (1) utility operations, including 

preparedness and response; and (2) engineering design and 

facility performance. The first category includes utility organization, energy sources, portable equipment, communications, inventory, emergency plans, mutual aid, training, 

recovery planning, and vulnerability assessment; the second 

category includes vulnerability assessment and the design 

and construction of equipment and facilities to resist earthquake-induced ground motion. 

The field observations and the resulting lessons learned 

were assembled both from our damage reconnaissance and 

from numerous discussions with utility personnel in the 

months after the earthquake. Additional information on water and wastewater utilities was presented by Benuska (1990). 

The utilities investigated included five for water and three 

for wastewater, specifically the water and the wastewater utilities of the East Bay Municipal Utility District, the water and 

the wastewater utilities of Hollister, the water utility of Sunny 

Slope, the water utility of Santa Cruz, the wastewater utility 

of Sacramento, and the San Jose Water Co. of Los Gatos. 

ORGANIZATION 

The organization and management style practiced at 

water utilities significantly affects preparedness, immediate 

response, and focus of attention of field personnel. All the 

utility personnel interviewed indicated that although they 

believed that their organizations did fairly well during and 

after the earthquake, they made important improvements in 

subsequent months. Included in the improvements that were 

frequently identified were better definition of leadership roles, 

clearer statement of unit duties, improved emergency plan- 
A88 PERFORMANCE OF THE BUILT ENVIRONMENT 

ning to reflect the detailed events that must be dealt with in 

real disasters, and better preparation through "what if thinking and plan exercising. 

ENERGY SOURCES 

When electrical power was lost, managers searched for 

immediate remedies, and in the months after the earthquake, 

they identified several salient points that can help provide 

better preparedness for the "next earthquake": 

Water and wastewater utilities should maintain close relationships with the local electrical-power company to ensure that the priorities of the utilities and the effect on 

these priorities of potential shutdowns (as requested by 

State or local authorities) are understood in advance of a 

disaster. Such shutdowns could affect the utilities' headquarters, treatment plants, pumps, and other facilities. Deliberate shutdowns are commonly avoidable. 

Portable electrical-power generators should be provided 

with the proper fittings and connections as required for 

each intended use. These generators should be periodically tested under load at each location where they may 

be used, such as at operations centers and pumping plants. 

Permanent engine-driven electrical-power-generator sets 

should be provided at critical support facilities, such as 

administrative headquarters, maintenance buildings, treatment plants, major control centers, laboratories, and petroleum-fuel stations. 

Regularly scheduled periodic tests of emergency-power 

or engine-driven systems should be conducted under load; 

power units may perform well without load but may fail 

when operated under emergency-power demands. 

PORTABLE EQUIPMENT 

All the utility personnel interviewed noted that more 

portable equipment was needed than was on hand in their 

own organization. These shortfalls were commonly due to 

budgetary constraints. However, within 24 hours of the earthquake, those responsible for these constraints became painfully aware of the consequences of false economy in regard 

to portable equipment. Additionally, it was observed that portable utility equipment needs the following attention: 

Perform preventive maintenance on a scheduled basis and 

test at least quarterly. 

Shelter portable lights, chlorinators, pumps, and other 

equipment in earthquake-, flood-, and fire-safe buildings 

so that they will be available when needed most. 

Store portable equipment in dispersed locations if the operations area of the utility requires access by way of tunnels and bridges or slide-prone routes. Preplan alternative 

access routes. 

Ensure that personnel know how to operate portable equipment and know the equipment's limitations. 

COMMUNICATIONS AND 

PUBLIC INFORMATION 

The following factors were determined to be required to 

ensure that utility response was adequate in the areas of communications and public information: 

In the calm atmosphere of predisaster operations, create 

fill-in-the-blank media-release forms with advice from the 

local media. It is also helpful to acquaint media personnel 

with the format of your utility's emergency-information 

statements. 

During the disaster, use these preplanned forms to let customers know, through the media, that their utility is staying on top of problems. Provide early damage reports and 

frequent updates. 

Develop a centralized source for the distribution of these forms 

and the dissemination of other information to the public, to 

ensure that accurate, consistent, and timely information is 

provided to the public by way of the mass media. 

Preplan employee communications for early notice of (1) 

how the utility is doing, (2) what they should do, (3) what 

transportation options exist, and (4) other employee and 

family instructions and information. Taped messages are 

useful and should be updated. 

Reserve a separate radio frequency dedicated to emergency 

utility operations. Sharing a frequency with other community disaster organizations (such as fire, police, or emergency medical services) may be a source of difficulty for 

small utilities. A base station, alternative base station, and 

emergency-power supply, as well as compatible mobile and 

personal radios, should be part of this system. 

Before the disaster, request that the utility's telephone lines 

be put on an essential-service status list, to provide the utility 

with improved access to dialtone when the telephone system is congested. 

Develop a radio-communication system that is not part of 

the public-switched-network lines, and acquire cellular telephones as a backup to the public-switched-network lines. 

Keep a supply of radio transceivers on hand. Most utilities 

discovered that they had too few portable radio transceivers, 

and quickly purchased more. Station-to-station two-way radios were preferred over base-operated systems because if 

the base was out, all radio communications were lost. 

Maintain stocks of batteries for battery-operated communication equipment. 

Provide a means for radio communication with police, fire, 

and emergency medical services in communities served by 

the utility. Frequency-scanner receivers can provide such 

emergency contact at an economical price. Test exercises 

of these systems are vital to ensure smooth communications during a disaster. 

Make previous arrangements with the local office of Radio 

Amateur Civil Emergency Services (RACES), so that amateur radio operators will report to the utility during an emergency. 

Prepare for handling postdisaster investigations. Utilities 
LESSONS LEARNED BY WATER AND WASTEWATER UTILITIES A89 

that are significantly damaged during an earthquake should 

expect visiting inspection teams who may arrive from all 

over the world. For this reason, organizational outlines, 

maps, system data sheets, and other informational handouts should be available for these visitors. These teams are 

composed of technical personnel who can be valuable 

sources of information to the utility. 

INVENTORY 

The earthquake emphasized the following important lessons related to the adequacy of supplies and their ease of 

access: 

ft Maintain an adequate inventory of repair materials to meet 

the needs of reasonable disaster-damage scenarios. Some 

smaller utilities had essentially no inventory of repair clamps 

and fittings for the full range of pipe sizes damaged (figs. 1, 

2). These utilities had to order the needed material from suppliers and hope that mutual aid from another utility would 

provide the needed material in the meantime. 

ft Maintain a full range of petroleum fuels in onsite storage 

or in drums (within local fire-department limits). In case 

of a power outage, a method (and necessary equipment) 

should be provided so that fuel can be loaded, transported, 

transferred, and delivered to equipment. It may be more than 

a week before tank-truck supplies will reach your area. The 

delivery of fuel may be delayed because of blockage of access routes or the fuel needs of higher-priority organizations. 

Before the disaster, discuss with current suppliers the probable availability of materials during a major emergency. Identify potential additional suppliers. Informal bid and payment 

procedures need to be in place before a disaster occurs. 

Prepackage and prelocate repair materials in locations that 

are difficult to reach so as to significantly speedup repair and 

recovery activities, including the proper number and sizes of 

such vital materials as pipes, valves, and repair clamps. 

EMERGENCY-RESPONSE PLAN 

In general, utility emergency-response plans (ERP's) 

were not well documented or preexercised before the earthquake. For this reason, utilities are encouraged to take the 

following steps: 

ft Develop or update a utility ERP. Most utilities contacted 

in the earthquake-affected area admitted serious shortcomings in this category. In most places where reasonable 

earthquake performance was reported, successes were attributable to the isolated existence of specific procedures 

or to intelligent employee response in the absence of a 

plan or procedure. (A "plan" describes the coordination 

of the response of all units of an organization; a "procedure" describes functional details and generally applies to 

a specific unit of the organization.) 

ft Coordinate the utility ERP with the plans of other agencies with whom the utility will function during a disaster. 

For example, including the police in the ERP and in exercises of the ERP would assure that the utility has emergency access priority to damaged facilities. 

ft Create an "incident-logging procedure" to record reports 

of and responses to events, including descriptions, times, 

reporter names, and actions taken. This procedure will provide a good working mechanism to handle first reports and 

to set priorities. 

Figure 1.-Split on 14-gage-steel spiral-welded water 

barrier in 60-in.-diameter raw-water line. 

Figure 2.-Repair crew replacing section of split 60-in.-diameter 

raw-water line shown in figure 1. 
A90 PERFORMANCE OF THE BUILT ENVIRONMENT 

Provide guidelines for water-quality sampling, alternative 

laboratory testing, notification of the public, reports to the 

health agencies, and related actions. 

Remember that microbiologic sampling is not a substitute 

for disinfection in the operation of water-distribution systems. The ERP should ensure that a sufficient inventory of 

disinfectant supplies will be available, even if vehicular 

access is limited. The ERP should include the training of 

personnel in the application of the disinfectant. 

Train personnel in emergency procedures. Health departments 

may be available for counsel, but utility operators must evaluate information and decide on a course of action to ensure 

maintenance of water quality. Therefore, the plan of action 

for potential problems should be determined before a disaster, and the plan should be periodically exercised. 

Orient employees in the content and use of the ERP by 

conducting periodic test exercises with conditions as close 

to real disaster conditions as possible. During these exercises, it is vitally important to practice communications 

with agencies that may assist in a mutual-aid relationship. 

Have State utilities submit their ERP to the California Office of Emergency Services and arrange for formal recognition of the participation of the utility under the State's 

Master Mutual Aid Agreement. Utilities in other States 

should submit their ERP to the appropriate State agency 

and arrange mutual-aid agreements with other utilities. 

Have State utilities participate in the activities of the Utilities Division of the California Office of Emergency Services. If such a division does not exist in other States, be 

instrumental in its creation. 

Ensure that the ERP includes a procedure for the operation of 

water-treatment facilities when various parts of the facility 

are inoperable because of earthquake damage. This procedure should include details of how a plant might be bypassed. 

Discuss this procedure with public-health officials. 

Create adequate identification cards for utility personnel 

and provide copies of valid cards to local police agencies, to 

improve checkpoint passage during an emergency. 

MUTUAL-AID PLANNING 

A mutual-aid plan is a formal written agreement signed 

between two or more organizations before a disaster; it identifies the actions and material that will be provided cooperatively during a disaster. The following activities were observed 

to be vital to successful mutual-aid preparedness: 

Ensure that formal written mutual-aid agreements exist with 

other agencies. 

Inform utility personnel about mutual-aid plans, procedures, 

and the utility's expectations. 

Participate in regional interagency meetings and test exercises to identify problems and improve performance. 

Be prepared to answer requests for aid from adjacent military facilities or other Federal or State organizations. During the 1989 Loma Prieta earthquake, these organizations 

were unprepared to quickly handle the number of pipe 

breaks that occurred. 

Obtain previous authorization from fire-department officials for the utilization of fire engines as booster pumping 

equipment (fig. 3). This authorization will require cooperation between the water utility and the fire department 

for the provision of between-zone hydrants and portable 

hydrant assemblages (fig. 4), and may require that both 

organizations share in the cost of procuring these portable 

assemblies, which are made up of pipe crosses, regulators, 

valves, and large-diameter firehoses (max 5-in. diam for 

larger cities). Water utilities should obtain the necessary 

adapters for the various firehose diameters and thread types. 

Maintain close personal relationships with the personnel 

of nearby utilities to ensure cooperation under highly 

stressed conditions. Predisaster discussions regarding potential emergency situations and how the agencies will resolve them can prevent serious misunderstanding during 

an emergency. 

TRAINING 

Training translates good plans into good performance 

during a disaster. Critical training elements include the following: 

Acquaint all employees with the ERP to ensure that everyone understands the plan's goals and will work harmoniously to carry them out. 

Conduct training in all of the planned emergency actions 

and crosstrain employees to permit the coverage of essential jobs in an emergency. Training should include regular 

retraining of current employees, new-employee training, 

ERP exercises, and problem-solving sessions. 

Train employees in emergency communication procedures, 

including not only maintaining radio and telephone communications within the utility but also prohibiting individual 

Figure 3.-San Francisco Water Department pumper providing 

booster-pump services to supply areas that were out of water because of numerous earthquake-related water-main breaks. 
LESSONS LEARNED BY WATER AND WASTEWATER UTILITIES A9 1 

employees from communicating with the mass media. Instead, employees should be trained to refer all requests for 

information to a centralized source for the dissemination 

of information to the public, to ensure that accurate, consistent, and timely information is provided to the public by 

way of the mass media. 

Thoroughly inspect facilities immediately after an earthquake. In Santa Cmz, 1,100 gal of zinc orthophosphate 

solution used for pH control was missing. The material was 

discovered in a plant's treated-water channel and removed; 

close inspection avoided a problem. A check valve with a 

failed exterior spring was the cause of the spill. 

"Boil order" planning is important, so that when called 

upon, the utility is prepared for action. Issue a "boil order" 

if any of the following events occur: 

0 Reduced pressure in water mains, which will create a 

vacuum. 

0 Water-main breaks too numerous to repair quickly. 

0 Sewers overflowing to the level of the manhole covers. 

0 Indications of broken sewers. 

"Boil order" instructions to customers should include: 

0 Bring water to a rolling boil and then turn off the heat. 

0 Water is drinkable when it cools. 

0 If heat is unavailable, filter water through a gauzelclean 

cloth, then mix in one teaspoon of bleach per gallon of 

water. 

0 Let bleach-water mixture stand for 15 minutes. 

0 Water is drinkable after 15 minutes. 

Review the section entitled "Coliforrn Rapid Detection Bacteriological Methods" in the manual by the American Public Health Association (1 989, sec. 92 1 1); 7-hour tests may 

be applicable. 

Train personnel to respond only to utility leaders and not 

to other public-employee supervisors who may tell them 

what their priorities should be. Conduct predisaster discussions with police and fire leaders to encourage chainof-command communications, so as to avoid conflicts in 

Figure 4.-Portable hydrant assembly used by the San Francisco 

Water Department consisting of valves, a regulator, and fire hosefitting connectors. 

the field during an emergency. As a corollary, field forces 

need to keep their own supervisors well informed, especially with respect to valve closures, so as to ensure that 

Emergency Operations Center (EOC) information will be 

accurate and that supervisory decisions will be correct. 

LONG-TERM RECOVERY PLANNING 

Planning only for the immediate response to an earthquake and other disasters is insufficient; long-term recovery 

actions must also be considered. Recovery planning must take 

into account broader issues, such as: 

Options to repair, such as abandonment or replacement at 

another location. 

Redundancy of pipelines and other facilities. 

Relocation away from newly observed fault areas. 

Rate-structure change reflecting the cost of loss-mitigation 

programs. 

Personnel training and procedures for recovery. 

Review and update of communication systems. 

Review and update of standard designs no longer appropriate for the area. 

Shared use with other agencies (for example, emergency 

equipment, laboratory facilities). 

In addition, a procedure for the collection of utility revenues during the recovery period should be identified, including turnoff and turn-on procedures for emergency periods, 

especially with respect to nonpayment. Recordkeeping during emergencies is crucial to the recovery of insurance-covered costs or StateFederal emergency funds. These records 

should include: 

A first survey and quick estimate of the damage, to assist 

the State governor in determining whether a state of emergency should be declared. 

In accounting for the cost of disaster recovery, a mechanism of differentiating between costs for "repair to what it 

was" system repair and costs for system improvementlloss 

mitigation. 

A detailed description of the limits of work and the materials ordered (including pickup tags, trucking records, and 

so on), with the realization that State and Federal audits 

may not be performed for 3 or more years. For larger utilities, recovery of costs under $3,000 per damage site is probably not economical. 

VULNERABILITY ASSESSMENT 

AND MITIGATION OF HAZARDS 

Each utility should develop a program to assess and minimize its vulnerability to earthquake damage. This program 

should consist of the following steps: 

Conduct a vulnerability assessment of the utility's treatment plant, reservoirs, and water-distribution facilities and 
A92 PERFORMANCE OF THE BUILT ENVIRONMENT 

equipment, consisting of a field assessment to identify the 

potential earthquake hazards to the utility's entire system. 

These hazards could be grouped in one of three categories; 

structural, operational, or geotechnical. For example, facilities and piping systems located in areas of alluvial soil 

or uncompacted fill are highly susceptible to damage in an 

earthquake. These areas would include old shorelines (Marina District of San Francisco), old riverbeds, and filled-in 

ponds. 

After the field assessment, itemize the utility's vulnerable 

elements, including items in the water-distribution system 

(such as valves, pumps, or lengths of piping), items in water- and wastewater-treatment plants (such as pumps, cylinders, electrical equipment, or computers), and such major 

items as tanks, reservoirs, and entire buildings. 

List the vulnerable elements in the order of their importance to the utility's operation. For some elements, a conscious decision may be made to accept the existing risk 

without mitigation; these elements should be specifically 

identified in writing. 

On the basis of this prioritized list, develop a plan for the 

mitigation or elimination of the hazard to these elements. 

Place this hazard-mitigation plan into action. 

valves, and the service connections were either 0.75-in.-diameter PVC pipe or 1-in.-diameter copper tubing. Only one 

of the asbestos-cement pipes was damaged; however, many 

breaks occurred on the customer side of the connection to the 

public system, as a result of differential ground settlement in 

the alluvial soil of the faulted area. Only two of the main 

breaks occurred in pipes 2 in. or smaller in diameter. 

In the area of cast-iron water mains, some of the private 

breaks in the water-distribution system were due to shearing 

of the connection of the service tubing to the house; other 

breaks were due to shearing of the connection of the service 

tubing to the water main. As evidenced by the significant 

motion in many private residences, this shearing was caused 

by relative motion between the houses and the distribution 

mains. For example, within a four-block residential area 

(approx 700 by 1,700 ft), at least 10 houses were knocked off 

their foundations because of ground-motion-induced shear 

failure of the cripplewall (figs. 5, 6), and evidence of pavement and curb separation and differential motion and sidewalk seam opening of 1 to 4 in. (figs. 7, 8) was observed. 

These curb, pavement, and house motions indicate the significant ground motion and the settlement of alluvial soil that 

EXAMPLES OF WATER AND 

WASTEWATER LINES VULNERABLE TO 

EARTHQUAKE DAMAGE 

TYPES OF PIPE IN 

WATER-DISTRIBUTION SYSTEMS 

The 1989 Loma Prieta earthquake demonstrated the superior performance of asbestos-cement and polyvinyl chloride (PVC) pipe relative to cast-iron pipe. Although installation 

of asbestos-cement pipe has ceased in the United States because of the potential health risks associated with its use, we 

present the following observations to alleviate concerns about 

the seismic performance of existing water-distribution systems composed of this material. 

For example, in the rural town of Hollister, the water 

utility was significantly damaged. (The San Andreas fault is 

about 10 mi west of the town, and the Calaveras fault traverses 

the town.) The water mains near the branches of the Calaveras 

fault were mostly pre-1950 vintage, consisting of 4- and 6- 

in.-diameter cast-iron mains, with lead-caulked bell-and-spigot 

connections. At the fault crossings, no special precautions had 

been taken, such as the use of flexible couplings. In this area, 

other lifelines and residences and designed structures were 

significantly damaged, and 1 1 water-main breaks occurred to 

cast-iron pipes. In a different area of Hollister, but still in the 

vicinity of the Calaveras fault branches, the water mains were 

6- and 8-in.-diameter asbestos-cement pipe in 13 ft sections, 

with rubber-ring-collar connections; the average ground cover 

was 3 ft thick. The asbestos-cement pipes had cast-iron gate 

Figure 5.-Typical shear failure of cripple wall in a house in Hollister 

due to lateral ground motion and insufficient shear connectors. 

Figure 6.-Repair of cripplewall in a private residence in Hollister. 
LESSONS LEARNED BY WATER AND WASTEWATER UTILITIES A93 

occurred during the earthquake. This motion and settlement 

caused the numerous water-service connection breaks. 

In the area where the water-distribution system consisted 

of rubber-gasketed asbestos-cement and PVC pipe, only one 

pipe break was reported, in a 0.75-in.-diameter plastic connection to a house: a pullout break caused by relative motion 

between the house and the distribution main. 

The scarcity of breaks in asbestos-cement and PVC pipe 

is attributable to several factors. The joints of both types of 

systems are more flexible than the lead-caulked joints in castiron pipe segments. (In asbestos-cement pipe, joints typically 

contain rubber gaskets, whereas in PVC pipe, the articulated 

joint allows for some pipe motion without breakage. The old 

lead joints of cast-iron pipes are inflexible, and any displacement will cause a leak.) Additionally, the wall thickness of 

old cast-iron pipe is likely to have been thinned by corrosion, 

making it vulnerable to fracture or rupture during an earthquake, whereas asbestos-cement and PVC pipe do not corrode and thus should maintain their design strengths. Also, in 

both asbestos-cement and PVC pipe, the typical segment 

length of 13 ft provides more flexibility than that provided by 

the typically shorter segment lengths of cast-iron pipe. 

Figure 7.-Buckling of sidewalk in Hollister due to ground settlement. 

The superior earthquake performance of asbestos-cement 

pipe was also demonstrated in areas farther away from the 

epicentral region. In the East Bay Municipal Utility District 

(EBMUD) in Oakland, the total number of repairs in the water-distribution system exceeded 120. Only 13 of these repairs occurred in asbestos-cement pipe, and the rest in steel, 

PVC, and cast-iron pipe. Many of the breaks in cast-iron pipe 

were caused by compression, as indicated by jammed bells. 

Numerous shear and bending failures were also reported. One 

break in a 20-in.-diameter line in Oakland caused a rapid loss 

of water level in EBMUD's central reservoir; this break was 

caused by a thrust failure in the bell-and-spigot connections 

of an 18-ft segment of cast-iron pipe that had been laid in 

1916 in an area underlain by bay mud (fig. 9). In EBMUD's 

water-distribution system, the superior earthquake performance (2 to 3 times lower repair rate) of asbestos-cement 

relative to cast-iron pipe was again due to the factors mentioned above for Hollister (see Eidinger, this chapter). 

LOCATION OF 

WATER-DISTRIBUTION LINES 

Utilities should identify the locations in water-distribution systems where pipes are vulnerable to damage. The 1989 

Loma Prieta earthquake caused much damage to buried pipe 

in areas of uncompacted fill soil and in naturally occurring 

sand and alluvial soil; however, very little damage to pipe 

was reported in areas of firmer or compacted fill. The damage occurred because long runs of pipe were subjected to differential ground settlement or differential lateral ground 

motion. 

Additionally, pipes are commonly conveyed across bodies of water by vehicular bridges. Because bridges constructed 

in areas of uncompacted fill or alluvial soil are supported on 

piles, differential settlement and differential lateral motion 

between the bridge and the roadway may be caused by an 

earthquake. During the 1989 Loma Prieta earthquake, such 

motion broke pipes conveyed by the San Francisco-Oakland 

Bay Bridge and by several bridges in Santa Cruz (fig. 10). 

Figure 8.-Cracking of pavement in Hollister due to differential 

ground settlement. 

Figure 9.-Failure at bell-and-spigot connection of 20-in.-diameter 

cast-iron pipe in Oakland due to axial thrust in waterline. 
A94 PERFORMANCE OF THE BUILT ENVIRONMENT 

Utilities also need to be aware that long-term creep of 

the ground may significantly affect buildings, equipment, and 

pipes. For example, in the Hayward fault area of Oakland, 

the ground creeps continually at a rate of about % to % in. per 

Figure 10.-Differential lateral motion between curb on a pile-supported bridge and the curb on approach road would break any waterlines conveyed by this bridge in Santa Cruz. 

year, causing the pipe shown in figure 11 to become inclined 

from its originally vertical position. In a pumphouse located 

about one block from this pipe, creep has caused gradual 

movement of the supports for the suction and discharge piping of several pumps (figs. 12, 13). 

GEOLOGY 

The 1989 Loma Prieta earthquake emphasized the fact 

that regional and local geology must be considered and understood during the planning and design of utility facilities 

and water-distribution systems. Many utilities adversely affected by the earthquake did not consider soil conditions adequately. Some facilities as far away as 100 mi from the 

epicenter were significantly damaged. 

One excellent source of information is the U.S. Geological Survey's "Soils Reports," which identify soil types, 

faults, and levels of anticipated ground motion in different 

areas. When this information is combined with information 

Figure 12.-Interior of water-pumping plant located near the Hayward fault in Oakland. Note pipe supports. 

Figure 11 .-Differential lateral motion between top and bottom of 

pipe in area of the Hayward fault in Oakland due to ground creep of 

about % to % inlyr. 

Figure 13.-Detail of gradual lateral displacement of pipe support 

shown in figure 12, due to ground creep in area of the Hayward 

fault. 
- - 

LESSONS LEARNED BY WATER AND WASTEWATER UTILITIES 

on local soil conditions, planning and design can be done to 

minimize earthquake vulnerability. Maps that locate geologic 

faults with respect to street names are useful in retrofitting 

existing facilities and water-distribution systems. 

The locations of breaks in the piping of water-distribution systems were useful in determining previously unknown 

minor geologic faults and areas of soil peculiarities. The 

records of these locations kept by many utilities on distribution-system maps have proved to be a great aid in the design 

and planning of future hazard mitigation. 

DESIGN AND CONSTRUCTION OF 

EQUIPMENT AND FACILITIES 

We observed a wide variation in the earthquake performance of structural facilities and operating equipment. In this 

section, we describe the earthquake performance of utility 

facilities and equipment in varying environments, noting the 

lessons that can be learned by designers and constructors. 

STRUCTURAL FACILITIES 

Utilities should assess the vulnerability of systems, 

equipment, and waterlines in masonry buildings. As an example, one significant private-waterline break occurred in 

Hollister as a direct result of the structural failure of an 

unreinforced-masonry building. This failure occurred when 

the building housing the International Order of Odd Fellows 

(IOOF) collapsed into an adjacent State office building, severing a 4-in.-diameter fire-sprinkler connector and causing 

significant water damage in the State office building. These 

buildings were located in downtown Hollister, on the east 

branch of the Calaveras fault. 

We noted that one two-story reinforced-masonry building which was located about two blocks from the IOOF building and also located on the east branch of the Calaveras fault 

sustained only superficial cracks in the facade and interior 

walls and ceilings. 

Utilities should assess their warehouse and storage buildings for vulnerability to earthquake damage. Warehouse contents should be restrained so that the horizontal motion of the 

Earth will not cause them to fall off shelves or topple over. In 

the Hollister area, two tiltup concrete warehouses and one 

metal-frame warehouse were significantly damaged when 

their contents toppled northward and knocked down much of 

the north walls of the buildings. 

EQUIPMENT ANCHORAGE 

Utilities should ensure that all equipment is positively 

anchored. Note that the anchor clip for the electronics cabinet shown in figure 14 provides a more secure restraint than 

that provided by a friction clip. The seismic-restraint straps 

shown in figure 15 anchor the underside of temporary office 

trailers to the ground. An example of a system-monitoring 

panel that is insufficiently restrained to prevent lateral motion at the top of the panel is shown in figure 16. Additionally, electrical and communications conduit should have 

enough slack that it will not stretch or break because of differential lateral motion between the conduit support and the 

panel. 

During any disaster, communications within a utility are 

vitally important. Thus, utilities should ensure that communication equipment is properly anchored to lessen its vulnerability. 

TANKS 

In regard to their performance during and after an earthquake, both reinforced-concrete and steel tanks have advantages and disadvantages. For both types of tanks, however, 

the 1989 Loma Prieta earthquake made the following points 

clear: 

Tanks should be easy to inspect periodically. 

Damage to the tanks should be easy to identify after an 

earthquake. 

Damage to the tanks should be easy to reliably repair after 

an earthquake. 

In particular, steel tanks require careful periodic inspection and maintenance to ensure that leg anchorage to the foundation and tension-bar adjustment and connections are 

maintained. 

For example, earthquake-induced ground and water motion significantly damaged a concrete tank in the Purisima Hills 

Water District (figs. 17, 18). This wire-wound posttensionedconcrete tank was constructed in 1964 by alternate pours of the 

vertical panels. The earthquake caused the collapse of the colFigure 14.-Typical anchor clip for an electronics cabinet, use to 

prevent it from overturning. 
A96 PERFORMANCE OF THE BUILT ENVIRONMENT 

Figure 15.-Seismic-restraint straps anchoring underside crossbeams 

of a temporary office trailer to ground. 

Figure 17.-Wire-wound posttensioned-concrete tank 

in the Purissima Hills Water District. Tank was constructed in 1964 by alternating pours of vertical panels. 

Figure 16.-Typical monitoring panel with no lateral restraint at top. 

Figure 18.-Water tank shown in figure 17 completely 

lost its contents because of collapse of the column-supported roofslab and opening of vertical panel join. 
LESSONS LEARNED BY WATER AND WASTEWATER UTILITIES A97 

urn-supported roof slab and the rupture of a panel joint. The 

entire 1.1 million gal of water in the tank was lost. 

Because tanks are susceptible to significant motion of 

their contents and support pad, the flexibility of the waterline connections to the tank is vitally important. Flexible connections should be provided that will allow relative motions 

of at least 6 in. (vertically and in both horizontal directions) 

between the tank and the waterlines (fig. 19). 

SUMMARY 

The implementation of these lessons learned will be difficult and costly in both time and material; however, the utilities that implement them will have made a significant 

investment in earthquake-disaster mitigation that will pay dividends both in financial costs and in public satisfaction after 

the next large earthquake. In geographic areas of low seismic 

risk, where seismic retrofit is much more difficult to justify, 

the appropriate seismic upgrades can commonly be performed 

during normal refurbishment. 

ACKNOWLEDGMENT 

We acknowledge the considerable contributions from the 

following members of other postearthquake-damage-reconnaissance teams, all of whom are members of the American 

Society of Civil Engineers, the American Water Works Association, or the Earthquake Engineering Research Institute: 

Leva1 Lund, Donald Ballantyne, and Anshel Schiff. We especially thank the utility managers of the American Water 

Works Association, Californiflevada section: B.J. Miller, 

Norman Lougee, Brian Whitaker, Ronald Grasser, John Jones, 

and Richard McMillan. 

REFERENCES CITED 

American Public Health Association, 1989, Standard methods for 

the examination of water and waste water (17th ed.): Washington, D.C., American Water Works Association, 1,193 p. 

Benuska, Lee, ed., 1990, Loma Prieta earthquake reconnaissance 

report: Earthquake Spectra, v. 6, supp. 90-01,448 p. 

Figure 19.-Pipe connections to water tanks should be flexible enough to allow at least 6 in. of differential movement (both horizontal and vertical) between tank and piping. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF' THE BUILT ENVIRONMENT 

LIFELINES 

TRANSPORTATION SYSTEMS 

By Joel Markowitz, Metropolitan Transportation Commission 

CONTENTS 

Page 

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101 

102 

ABSTRACT 

Few of the various transportation agencies that serve 

the San Francisco Bay region had emergency-response plans 

to cope with a large earthquake, and there was no preplanning 

between agencies; however, agencies quickly established an 

informal group to exchange information and coordinate activities. The Metropolitan Transportation Commission expanded a previously scheduled meeting to bring together 

transit operators and other key players; weekly coordinating 

meetings were held. Data gathering by many agencies was 

expanded, but few preearthquake baseline data were available. Although there was some centralized communication 

of transportation status, most agencies handled their own 

press and public-information activities. One of the key impediments to planning was uncertainty about the availability 

of funding and what activities would be reimbursed. Diversity and some redundancy allowed a relatively rapid response 

to expand transportation resources, New institutional relationships established since the earthquake provide a foundation for better coordinated preearthquake planning. 

POSTEARTHQUAm TRANSPORTATIONSYSTEM MANAGEMENT 

In an area as large and diverse as the San Francisco Bay 

region, the effects of the 1989 Loma Prieta earthquake varied significantly from place to place, as did transportation 

needs. As a result, the transportation systems in the area were 

tailored, to the degree possible, to the different needs through 

a cooperative process involving many agencies. 

IMMEDIATE POSTEARTHQUAKE RESPONSE 

Although some individual agencies, such as the California Department of Transportation (Caltrans), had emergency 

contingency plans in place, there was no previous coordination of individual plans, no comprehensive regional emergency-transportation plan, and no previously established 

central coordinating point. Despite these apparent handicaps, 

the region's transportation agencies quickly mobilized and 

coordinated their efforts through informal working groups. 

On Wednesday, October 18,1989, the day after the earthquake, the lieutenant governor of California requested a special meeting to coordinate transportation. The Metropolitan 

Transportation Commission (MTC) already had scheduled 

its regular monthly Transit Operator Coordinating Council 

(TOCC) meeting for October 19 and was intending to refocus that meeting on the earthquake response. Caltrans requested that the meeting be enlarged to accommodate the 

lieutenant governor's request, and the MTC agreed. The meeting included not only the transit operators and Caltrans but 

also representatives of the Urban Mass Transportation Administration (now the Federal Transit Administration), the 

Federal Highway Administration, the Federal Emergency 

Management Agency, the U.S. Coast Guard, the California 

Public Utilities Commission, the California Highway Patrol, 

the Ports of San Francisco and Oakland, private ferry operators, and others. 

After that meeting, a major press conference was called 

for Saturday, October 21, to inform the people of the San 
A100 PERFORMANCE OF THE BUILT ENVIRONMENT 

Francisco Bay region about what transportation services 

would be available to them the next Monday morning. All 

participating agencies contributed materials? which the MTC 

took the responsibility of reproducing and assembling into 

press kits along with additional maps? basic regional travel 

data? and telephone numbers to expedite use by the media. 

The maps were even provided in computer-disk format so 

that newspapers could more easily print them. 

After that first week, these special TOCC coordinating 

meetings were held weekly to facilitate the exchange of information on service adjustments and to keep everyone apprised 

of evolving funding and planning issues. All the participants 

were extremely cooperative and responsive. 

This process has pointed to the fact that no amount of 

previous planning could have precisely anticipated the transportation consequences of the earthquake. The flexibility afforded by regular communication enabled the region to easily 

adapt its response as travel patterns shifted. 

OPERATIONS DURING 

THE RECOVERY PERIOD 

After Monday? October 23? the MTC produced a daily 

summary of key regional travel indicators. Earlier, the MTC 

had published only annual data for transit operators and semiannual counts for the San Francisco-Oakland Bay Bridge and 

the Caldecott Tunnel. The transit agencies and bridge and ferry 

operators transmitted data to the MTC by telephone? facsimile 

machine? or in person after the end of the morning commute 

period. The report? published each afternoon? updated the daily 

totals for the previous day and included that morning's commute. The report had wide distribution and was the principal 

summary used for discussion at the special weekly coordinating meetings. 

Although these reports were adequate for general trend 

analysis7 it was up to each transit operator to monitor specific 

transit services at the route level and make adjustments as required. Any service adjustments were reported to the MTC so 

that public information could be updated. 

In addition to the basic travel data, several surveys were 

mounted to gather more detailed information about how travelers adapted their behavior. Owing to the immediacy of the need 

and the uncertainty in the early weeks about the date when the 

San Francisco-Oakland Bay Bridge would reopen? several agencies organized independent but complementary surveys. These 

surveys were coordinated through weekly meetings sponsored 

by the University of California? Berkeley's Institute of Transportation Studies. MTC staff conducted a survey of passengers 

on all of the newly established emergency ferry services. The 

Bay Area Rapid Transit (BART) district administered an onboard 

survey of its patrons (Cambridge Systematics7 Inc.? 1991). 

Caltrans conducted vehicle-occupancy counts and license-plate 

surveys at the three bay bridges and other locations and followed up with a mailout travel survey. The university conducted 

a regionwide telephone survey about general travel behavior 

(Transportation Center, 1990-9 1). Golden Gate Transit conducted a survey of its patrons? and the Bay Area Council conducted a survey of employer response. 

The analysis was somewhat hampered by a lack of detailed preearthquake data. Occupancy counts on routes other 

than the San Francisco-Oakland Bay Bridge and the Golden 

Gate Bridge have been rare. No general travel data had been 

collected since the MTC is 198 1 survey? although BART conducted a patron survey in early 1987. 

After the first weekend press conference? it was clear that 

the changing requirements necessitated frequent updates for the 

public through the major media. It was agreed that Caltrans7 

and the MTC's public-information offices would be the central 

coordinating point? but it was left to each operating agency to 

develop and disseminate its own detailed materials to the press. 

and public. Caltrans published a "Commuter Guide," and the 

MTC published an updated guide with maps showing the locations of new or changed services. The public-information officers of these two and other agencies met several times? but 

facsimile and telephone contact were the principal means of 

keeping everyone informed. 

With the initial financial backing of the MTC, RIDES for 

Bay Area Commuters opened a regional 800 hotline on October 24 to answer requests for information on ride sharing and 

public transportation. The first such regional transportation 

hotline? it proved particularly effective as a supplement to the 

printed materials and media announcements. The hotline was 

discontinued shortly after the San Francisco-Oakland Bay 

Bridge reopened. 

OBSERVATIONS AND 

RECOMMENDATIONS 

COORDINATION AND 

CENTRAL DECISIONMAKING 

Although the informal coordinating structure described 

earlier worked well? it was complicated by two factors. First? 

coordination was more complex because of the multiplicity 

of actors. There was no central decisionmaking body because 

each agency's management was limited by the authority 

granted by its respective policy board. There was a tacit understanding that Caltrans was the dominant actor, but otherwise? decisions were made independently, and there was no 

definitive agreement on central decisionmaking authority. 

Nonetheless? cooperation was excellent, and no major policy 

conflicts occurred. 

UNCERTAINTY ABOUT THE 

AVAILABILITY OF FUNDING 

After the earthquake? there was continual uncertainty 

about the availability of funding from Federal and State 

sources, especially for such nontraditional emergency func- 
TRANSPORTATION SYSTEMS A101 

tions and public-information programs on transportation alternatives. Even though the U.S. Congress and the California 

Legislature acted quickly to establish emergency funds, 7 

weeks after the earthquake, it was still unclear how much of 

which funds could be committed for which purposes, with 

any degree of confidence that the expenditures would be subsequently upheld as reimbursable. This uncertainty in resources 

somewhat hampered decisionmaking on emergency-service 

provision. Of the two issues of multiple actors and funding 

uncertainty, funding uncertainty is clearly the major obstacle 

to more effective planning. The regular coordinating meetings continued as long as they were needed, but the decisions 

that could be made at those meetings were severely constrained by questions about funding. 

PUBLIC-TRANSPORTATION RESOURCES 

IN THE SAN FRANCISCO BAY REGION 

Because of its longstanding commitment to public transportation, the San Francisco Bay region was able to marshal a 

substantial array of transit-service alternatives. The variety and 

depth of public transportation services already in place allowed 

a comprehensive and flexible system of rail, bus, and water transport, complemented by new highway high-occupancy-vehicle 

facilities, which were put in place virtually overnight. Without 

a strong local transit funding base, some degree of redundancy, 

expansion capacity, and widespread use of public transportation, such a response might not have been possible. 

DIVERSIFICATION OF REGIONAL 

TRANSPORTATION SYSTEMS 

Air-quality, traffic-congestion, and land-use issues have 

long been the impetus for expanding the region's public-transportation system. The earthquake reminded us of the fragility 

of a regional economy dependent on bridges, tunnels, and 

landslide-prone highways. In investments, it is well established that diversification is the best protection against unanticipated setbacks. Similarly, beyond the immediate need for 

repair or replacement of facilities, a long-term need exists for 

Federal and State support to continue the expansion of regional public-transportation facilities in all major corridors, 

so as to diversify the region's transportation system and give 

it the ability to withstand shocks to parts without catastrophic 

damage to the whole. 

EMERGENCY PLANS 

All seismically vulnerable transportation systems should 

be immediately evaluated, and priorities established for dealing with them. Alternatives to these facilities should be identified and enhanced as needed to provide emergency capacity. 

Generalized regional contingency plans should be outlined 

for the most likely disaster scenarios. Management, operations, and planning exercises should parallel the frequent disaster-response exercises. 

FORMAL COORDINATION PROCEDURES 

More formal understanding should be established of the 

respective roles and authorities of the various agencies. Where 

necessary, statutory changes might be required to achieve more 

effective coordination through a clearer delineation of powers. Emergency-communication arrangements among affected 

agencies should be upgraded and tested on a regular basis. 

Funding issues should be worked out in advance so that no 

question remains about the availability of resources. Flexibility in the use of funds is the paramount concern; decisions 

on how best to use resources should be delegated to the appropriate regional coordinating body, rather than by mode or 

funding agency. 

TRANSPORTATION-SYSTEM MONITORING 

The regular monitoring of travel in major regional corridors should be continued on a scaled-back basis. A continuing, 

low-level regional-travel-data-monitoring program should be 

established to provide reasonably current trend data at all times. 

PUBLIC INFORMATION 

Marketing and public information should be continued 

on a regional basis. A regional telephone information service 

should be continued, and a general regional public-transportation marketing and awareness program should be established 

to inform travelers of their alternatives. 

PREDISASTER PLANNING 

Effective response to future, more severe disasters could 

be limited by a lack of planning. No disagreement exists that 

this earthquake was merely a hint of what awaits the region 

when the major faults slip again closer to the San Francisco 

Bay region's urban center. The ability to effectively manage 

that catastrophe will not be limited by the dedication or resourcefulness of our citizens and institutions, which were 

superlative in this earthquake, but rather by the lack of adequate previous consideration of the issues raised above. 

LESSONS LEARNED AND 

CURRENT PRACTICES 

Since the initial evaluation reported above, there have 

been several activities to enhance future emergency-response 

capabilities: 

1. Caltrans has completed a survey of routes State-wide for 

designation as bblifeline" routes to supply regions with emer- 
A102 PERFORMANCE OF THE BUILT ENVIRONMENT 

gency relief. Funding and priorities for improvements to 

those routes are being explored. 

2. San Francisco Bay region public-transit operators have 

agreed on a general approach to evaluating and mitigating 

hazards in their systems (Metropolitan Transportation Commission, 1992), as well as responding to an earthquake (Metropolitan Transportation Commission, 1994). 

3. San Francisco Bay region ferry operators have agreed on a 

specific plan to provide emergency services on San Francisco 

Bay (Metropolitan Transportation Commission, 1996). 

4. The State has relinquished a radio frequency for use by 

transit agencies during emergencies. The MTC has helped 

the agencies procure and install radio equipment for baseto-base communications using that channel. 

5. The Association of Bay Area Governments (ABAG) and 

Caltrans have completed a project that maps the region's 

transportation facilities against the known seismic hazards. 

The complete report (Association of Bay Area Governments, 1997) will be the focus of workshops to be hosted 

in the various corridors within the San Francisco Bay region in order to bring the transportation providers and emergency response community together in each corridor to 

encourage further planning at subregionallcorridor levels. 

6. The Bay Area Partnership's Planning & Operations Committee and the Transit Coordinating Council endorsed the 

Trans Response Plan (TRP) in October 1997. The TRP defines procedures for developing and implementing a comprehensive multimodal transportation response to a regional 

disaster and coordinates this effort within the overall Standardized Emergency Management system (SEMS) implemented by the California Office of Emergency Services 

(OES). A "coordination team" that includes the U.S. Department of Transportation, the OES, Caltrans, and the MTC 

would convene to establish regional priorities for emergency 

response and recovery efforts. 

7. As of September 1996, a new regional telephone number 

has been established for multimodal transportation information. Although that system, called TravInfo, has not yet 

been sized for the volume of calls which would result from 

a major earthquake, it could be expanded quickly. In addition, the TravInfo project provides a central electronic data 

base of traffic and transit information that can be used for 

preearthquake planning and postearthquake monitoring. 

8. The MTC is leading an effort to better coordinate multiagency 

earthquake response ("regional emergency multimodal response plan"). The first multiagency tabletop planning exercise was held in November 1996. Multiagency planning 

exercises are now planned on an annual basis. 

9. The State OES has implemented a Response Information 

Management System (RIMS) to track resources and response information among the County Operational Areas. 

The RIMS reporting can be communicated by using the 

Operational Area Satellite Information System (OASIS) 

throughout the State. 

REFERENCES CITED 

Association of Bay Area Governments, 1997, Riding out future 

quakes; pre-earthquake planning for post-earthquake transportation system recovery in the S.F. Bay Region, Oakland, Calif. 

Cambridge Systematics, Inc., 199 1, BART userlnon-user panel 

survey analysis-phase 1 : report prepared for San Francisco 

Bay Area Rapid Transit District. 

Metropolitan Transportation Commission, 1992, Model operator 

contingency plan: Oakland, Calif. 

1994, Regional emergency [transit] management plan: Oakland, Calif. 

1996, Regional Ferry Contingency Plan: Oakland, Calif. 

Transportation Center, 1990-91, Studies on the Loma Prieta earthquake: Berkeley, University of California. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

TRANSPORTATION SYSTEMS-AIRPORTS 

By Anshel J. Schiff, Precision Measurement Instruments and Stanford University; 

and 

Luis Cusa, Los Angeles Department of Airports 

CONTENTS 

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ABSTRACT 

Runway damage was caused by soil liquefaction at 

Oakland International Airport and the Alameda Naval Air 

Station (ANAS). At the airport, 3,000 ft at one end of the 

runway was unusable until cracks across the runway were 

repaired. ANAS could not be used until massive repairs were 

completed. 

Windows in the control towers at San Francisco International Airport and Oakland International Airport were damaged. Because of the high ambient-noise level outside of the 

control tower due to arriving and departing aircraft, the loss 

of the windows at San Francisco International Airport severely disrupted operations. Dispatchers in the control tower 

could not hear or be heard because of noise, and repeated 

transmissions slowed operations by half. 

One of several engine generators at San Francisco International Airport did not start and the movement of an 

unanchored transformer at San Jose International Airport 

almost disrupted power there. Much of the equipment at airports, such as jetways and baggage handling equipment, is 

not provided with emergency power, and so the loss of commercial power can slow or interrupt airport operations. 

The terminal area at Oakland International Airport sustained minor structural damage. A building used by freight 

forwarders at San Francisco International Airport was severely damaged and subsequently demolished. Damage to 

the suspended ceiling in the North Terminal at San Francisco International Airport caused massive water leaks in the 

fire sprinkler system. 

INTRODUCTION 

A reconnaissance team investigated the San Francisco 

Bay region's three commercial airports in San Francisco, Oakland, and San Jose. The Alameda Naval Air Station (ANAS), 

located in the east bay just south of the San Francisco-Oakland Bay Bridge, and the Watsonville Airport were also investigated by means of telephone interviews. No strong-motion-recording instruments were located at any of the airports. 

Because of the unique soil conditions at most of the airports, 

it would be inaccurate to characterize airport ground motions 

by using nearby seismic records. Peak accelerations at bedrock near all the airport sites, except Watsonville, were less than 

0.1 g, but soil conditions at the airports amplified ground 

motions. 

The reconnaissance team visited officials at all three 

commercial airports on November 9, 1989. All airport managers reported that the response of their staffs to the earthquake was outstanding. Most offduty staff quickly returned 

to each airport and responded to contingencies as they arose. 

All three airports reported minor damage and (or) problems 

that affected, or could have affected, facility operations. Many 

of the shortcomings noted below are being addressed, even 

though they did not cause problems in the earthquake. One 
A104 PERFORMANCE OF THE BUILT ENVIRONMENT 

important purpose of postearthquake investigations is to identify things that either failed or did not operate as expected; 

little is generally said of the many operations, facilities, and 

equipment that worked well. The reconnaissance team came 

away from this investigation with the understanding that the 

airport authorities did a conscientious job in preparing for 

the earthquake. 

Airports are generally divided into two parts: airside 

facilities and operations and landside facilities and operations. The airside facilities include the runways, Federal 

Aviation Administration (FAA) facilities, control tower, and 

other facilities in some restricted areas of the terminal building. Landside facilities include access roads, garages, and 

passenger areas within the terminal building. 

The most significant earthquake damage was reported 

at Oakland International Airport, where soil liquefaction damaged 3,000 ft at the end of their only regular runway, as well 

as part of an adjacent taxiway. Soil liquefaction also severely 

damaged both runways at ANAS, which remained closed to 

air operations through December 1989. For various reasons, 

San Francisco International Airport was closed for 13 hours. 

For each airport, this section briefly describes the facility, 

identifies the reported damage, and discusses the earthquake's 

impact on various aspects of operations, concluding with 

general comments and observations. 

SAN FRANCISCO 

INTERNATIONAL AIRPORT 

San Francisco International Airport has two sets of parallel runways that intersect each other, with air traffic of about 

1,300 commercial flights per day and an annual passenger 

flow of 3 1 million. The annual freight flow through the airport 

is 570,000 t. About 31,000 employees work at the airport. 

The airport is located about 50 m from the epicenter, 

and the peak acceleration recorded near the airport was 0.29 g. 

EARTHQUAKE DAMAGE AT 

AIRSIDE FACILITIES 

One window of the control-tower cab fell out, along with 

a radar monitor. Ceiling panels, light fixtures, and fiberglass 

acoustic insulation fell in the control-tower cab, making it 

difficult to operate the facility. Typewriters, computer monitors, two of the three remaining radar monitors, and an additional monitor used in training fell from their supports and 

were inoperable. None of this equipment was anchored to 

desktops or stands. At the time of the reconnaissance team's 

visit, the 184-ft-tall steel support structure of the control tower 

was being evaluated by using X-ray inspection methods. Four 

minor injuries occurred to personnel in the tower when objects fell on them. Damage to the elevator in the control tower 

made it inoperable for 3 to 4 days. 

Despite a significant shift, possibly due to liquefaction, 

in the support structures for the lights that mark the runway 

approach and extend into the bay, the lights remained operational. All navigational equipment was unaffected, except for 

one of the instrument landing system's antennas adjacent to 

runway 28R, which was knocked down. The antenna was 

straightened, aligned, and put back into service. Fuel-storage 

tanks and piping systems were undamaged. 

EARTHQUAKE DAMAGE AT 

LANDSIDE FACILITIES 

Damage in the terminal areas was cosmetic and determined by each terminal's design. In the North Terminal, which 

was severely damaged, about 80 percent of the lightweight 

acoustic ceiling panels fell; they were supported on a wirehung T-bar framing system. Large, molded, monolithic ceiling elements, also supported by wires, swung more than 1 ft 

and were cracked by their impacts with structural support 

columns; none of the ceiling elements fell. Fire-suppression 

sprinkler heads that protrude through the ceiling were damaged by the motion of the suspended ceiling, resulting in the 

release of large volumes of water, which was 4 to 6 in. deep 

in boarding area F. Television flight monitors in several locations toppled from their supports above public-seating areas, 

but no one was hit. Wet floors became quite slippery, but no 

one was injured. The only injury reported was to an airline 

employee, who was found under an overturned check-in 

counter and could not move her legs. Water damaged a United 

Airlines' reservation computer located in the basement of the 

North Terminal. In the International Terminal, about 15 percent of the ceiling panels fell, and minor water damage was 

reported. Only a few ceiling panels fell in the South Terminal. 

A dry-type transformer, part of a unit substation, sustained a temporary short, which activated a protective circuit; 

it was reset, and the substation was put back into service. 

Then, 10 days later, this transformer caught fire from damage attributed to the earthquake. A two-story building, which 

had been temporarily used for airline cargo operations and at 

the time of the earthquake was being used as office space by 

freight-forwarding companies, was severely damaged and 

subsequently demolished. Workers continued to find damage 

that did not affect operations for several months after the earthquake. For example, a pipe hanger was broken, and a small 

suspended transformer in an out-of-the-way location that was 

unanchored to its support had shifted. 

POSTEARTHQUAKE OPERATIONS 

After the earthquake, one or two aircraft on final approach were flagged off to allow the reconnaissance team to 

inspect the runways. Normal flight operations were stopped 

immediately after the earthquake disrupted control-tower ac- 
TRANSPORTATION SYSTEMS-AIRPORTS A105 

tivities. A few flights were allowed to depart about 2 hours 

after the earthquake because they were loaded and no airtr*c problems were reported. Although the tower was physically capable of operating, it was closed because not enough 

controllers were available to safely operate it. About 1 % hours 

after the earthquake, the airport was officially closed; private 

cars were not allowed into the airport until the next morning. 

Most passengers at the airport at the time of the earthquake 

took airport buses or taxis to the city or to airport hotels; 500 

to 1,000 passengers stayed at the airport's South Terminal 

overnight, some using cots provided by the local American 

Red Cross. Blankets and pillows were supplied by some airlines, and food was supplied by the airport's food concessionaire. Two airport hotels, the AMFAC and the Hyatt 

Regency, were damaged and evacuated, leaving relatively few 

rooms available in the airport area. The airport was officially 

reopened and flight operations resumed at 6100 a.m. P.s.~. 

October 18. Initially operations were at about 50 percent of 

their normal level, partly because of the extremely high noise 

level in the tower with the missing window. Installation of a 

temporary plexiglass panel improved the situation on October 19, making the tower fully operational. It took several 

days for airlines to resume normal schedules because aircraft 

and crews had been diverted and had to be repositioned. 

Commercial power was lost shortly after the earthquake 

and was restored 2% hours later. All but 1 of the 14 diesel generators used to provide emergency power to airport facilities 

started automatically. That unit failed to start because the contacts of the relay that senses a power outage were burned; this 

relay is not used during normal periodic testing of the generators, and visual inspection did not detect the problem. The unit 

was started manually without difficulty. The diesel generator 

used to provide emergency power for communications was inspected by the reconnaissance team. The unit was mounted on 

well-designed, heavy-duty vibration isolators that had snubbers 

to prevent excessive motion. It appeared that the unit hit the 

snubbers during the earthquake. Batteries for starting the unit 

were supported on a stand about 3 ft above the floor and, except 

for a %-in.-high lip at the edge of the rack, were unrestrained 

(fig. 1). None of the batteries fell from its support during the 

earthquake. The FAA had one or more generators, which provided power to control tower instruments. Emergency power 

for the tank farm, which supplied fuel to aircraft, was supplied 

by the tank-farm operator. Emergency power was not provided 

to the jetways normally used by passengers to disembark from 

planes; instead, mobile stairways were used to unload planes 

on the ground while commercial power was unavailable. 

Because the airport does not use uninterruptable power 

supplies, a short interruption of power occurs before the emergency generators start. Repeaters, which are transmitters located 

around a site to ensure that radio communication can be picked 

up anywhere on the site, shut down because of the power outage and had to be reset manually. This resetting required that 

sites around the airport be entered, at some of which entry was 

delayed because access keys were unavailable. The temporary 

loss of some of the repeaters apparently did not cause any problems. The room currently used for airport emergency operations had, some time ago, been converted from a conference 

room. The lighting for this room had not been transferred over 

to circuits that are provided with emergency power, and so it 

became dark shortly after the earthquake. 

Elevators in the terminals were shut down by automatic 

seismic switches; none of the elevators was damaged, and all 

were restored to service in about 2 hours. Non-coin-operated 

telephones within the airport are on a Centrex system, which 

runs through the central office of the telephone company. Although the equipment was undamaged, airport personnel assumed that the system was not working because of a very long 

delay (as long as several minutes) in getting a dialtone. Radiocommunication channels became saturated, but they were manageable. Had damage been more severe, or had there been more 

minor or major incidents, such as additional personal injuries 

or a fire, saturation of radio communication would probably 

have interfered with the emergency response. Additional frequencies have since been added to the system. 

OAKLAND INTERNATIONAL AIRPORT 

Figure 1 ,-Emergency-power generator with unsecured 

batteries. 

International Oakland Airport has two runways and two 

FAA-certified control towers, one at the commercial airport and 
A106 PERFORMANCE OF THE BUILT ENVIRONMENT 

one at the adjacent general-aviation airport. The commercial 

airport has about 100 flights per day, with about 4 million passengers per year; annual freight flow through the airport is 

200,000 t. The main airport runway is 10,000 ft long and parallels the bay shoreline; it is normally used for commercial aviation. A second runway that is 6,200 ft long is now used primarily 

for general aviation, although it can also be used for commercial aviation. The main runway is built on hydraulic fill, 

from 5 to 10 ft thick, which was placed over young bay mud. 

The entire runway is of similar construction. The hydraulic 

fill is primarily poorly consolidated sand, and so it is particularly vulnerable to soil liquefaction in an earthquake. The older 

part of the airport is built directly on bay mud, rather than sand. 

The airport is located about 56 mi from the epicenter and 

the peak accelerations recorded near the airport ranged from 

0.19 to 0.29 g. 

EARTHQUAKE DAMAGE AT 

AIRSIDE FACILITIES 

About 3,000 ft at the north end of the 10,000-ft-long main 

runway, the adjacent taxiway, and the dike that borders the bay 

were severely damaged by soil liquefaction. Cracks across the 

runway were as much as 1 ft wide, and long cracks in the ground 

parallel to the runway were as much as 10 ft deep. In a few 

places, vertical offsets across the runway were as large as 1 ft. 

Sand boils on the runway and adjacent to the runway were as 

long as 40 ft in diameter. Abundant soil liquefaction occurred 

because the soils are especially susceptible. The control tower 

associated with the general-aviation field lost three windows, 

yet it continued to operate. One window was cracked in the 

commercial control tower. 

EARTHQUAKE DAMAGE AT 

LANDSIDE FACILITIES 

Soil liquefaction between two terminal buildings damaged 

two major structural columns that support the crosswalk between the terminals. The damage to these columns was probably due to relative motion between the two terminals, one of 

which is two stories high and relatively stiff, and the other a 

relatively flexible, taller structure. The rupture of a 16-in.-diameter water main caused the collapse of a service road. 

safety could be evaluated. The damaged columns affected only 

the walkway between terminals. The airport did not lose commercial power, and so it did not have some of the problems at 

other airports in the San Francisco Bay region. 

The damaged columns that support the interterminal 

walkway were shored up as a safety precaution, and the road 

under the walkway was closed to ensure that the shoring would 

not be damaged. The walkway remained in use for passenger 

traffic in the terminal. 

Communication problems at the airport affected ground 

operations. Ground operations (police and maintenance workers) shared one radio frequency, which quickly became overloaded. The airport has two authorized frequencies and is 

adding a second repeater so that the second frequency can be 

used. Cellular telephones were added during the reconstruction to alleviate this problem. A problem was also reported in 

communicating with crews who were cleaning up minor damage to the terminal. Normally, pagers are used to contact crews, 

who then use courtesy telephones to get their messages. Airport telephones on a Centrex system were effectively nonfunctional because their circuits were overloaded, and so 

runners were used to communicate with the cleanup crews. A 

problem in communicating with passengers when they were 

outside of the terminal was similar to the experience at the 

Burbank Airport after the 1987 Whittier Narrows, Calif., earthquake. At Oakland International Airport, some car-mounted 

megaphones were used, but more were needed. 

POSTEARTHQUAKE RESTORATION 

At the time of the earthquake, crews were resurfacing 

the main runway. An emergency change order was issued, 

and restoration of the runways began almost immediately, 

because crews and equipment were already on site. The plan 

was to do a partial restoration before the Thanksgiving rush 

and then complete the work before the Christmas rush. Extensive testing verified the absence of any concealed cavities 

below the runway. The repairs involved removing about 5 ft 

of soil on each side of the cracks, replacing it with engineered 

fill, and compacting the new materials. During the repair, the 

usable length of the runway had to be adjusted; at times, it 

was as short as 6,200 ft, but by December 25 it had been 

extended to 8,500 ft. The remaining 1,500 ft and the damaged taxiway were repaired after the award of competitive 

bids. Total repair costs for the airport were about $7 million. 

POSTEARTHQUAKE OPERATIONS 

SAN JOSE INTERNATIONAL AIRPORT 

Airport officials immediately shut down operations after the earthquake to allow runway damage to be evaluated. 

Flights were then diverted to the adjacent general-aviation 

runway, which is FAA certified. Within 1% hours, flights were 

shifted back to the main runway, which had been shortened 

to 7,000 ft. The passenger terminals were evacuated until their 

San Jose International Airport has three runways, which 

range in length from 4,800 to 8,900 ft. It has about 400 commercial flights per day, and the annual passenger flow is 20 

million. The annual freight flow through the airport is 7,500 

t. About 2,350 employees work at the airport. 
TRANSPORTATION SYSTEMS-AIRPORTS A107 

The airport is about 13 mi from the epicenter, and the peak 

accelerations recorded near the airport ranged from 0.1 to 0.2 g. 

EARTHQUAKE DAMAGE 

A window in the control tower fell out, and an overhead air-conditioning unit and fiberglass soundproofing panel 

fell into the control-tower cab. A 5-gal drinking-water bottle 

also caused some damage in the tower when it fell over. 

Within the terminal, a few ceiling panels fell from their Tbar supports. A signal lead that connected the base-station 

transmitter to its antenna broke because inadequate slack in 

the connection allowed motions of the antenna to overstrain 

the lead. A small dry-type transformer associated with the 

emergency-power generator came in contact with its cabinet 

and arced, but it remained functional. 

POSTEARTHQUAKE OPERATIONS 

Apart from a few minutes of interruption while the runways were being inspected, airport operations were not disrupted by the earthquake. Commercial power to the airport 

was lost shortly after the earthquake and was restored about 

5% hours later. The emergency-power generator started and 

operated as intended. Because the fuel-tank farm was not supplied with emergency power, aircraft and airport vehicles, such 

as police cars, could not be refueled. With the closing of San 

Francisco International Airport and the loss of part of the runway at Oakland International Airport, authorities considered 

diverting flights to San Jose International Airport. However, 

without the ability to refuel, many planes would not have been 

able to take off if they had landed. 

Soon after the earthquake started, the two police dispatchers evacuated their small office in the terminal, but they 

continued to work outside of the building adjacent to their 

office. They used a hand-held radio and repeaters to maintain 

communications. The public-address system could not be accessed from outside of the dispatching office, and so officers 

evacuated the terminal by walking through. Because the basestation transmitter was out of service, the hand-held radio 

was also used after the dispatchers returning to their office. 

ALAMEDA NAVAL AIR STATION 

ANAS consists of an airport, port facilities, and berthing 

facilities. The airport has two runways, 7,200 and 8,000 ft 

long, and a terminal building. The berthing facilities can accommodate 11 ships; 6 ships were berthed at the time of the 

earthquake. A squadron of six mine-countermeasure MH53E 

helicopters is based at ANAS, along with more than 20 other 

aircraft of various sizes, the largest of which is a DC 9. 

The airport is located about 60 m from the epicenter, 

and the peak acceleration recorded at the airport was 0.29 g. 

EARTHQUAKE DAMAGE 

Much of ANAS is built on fill, and substantial soil liquefaction occurred at the site. Both runways of the airport 

were closed because of severe damage, which consisted of 

5- to 8-in.-wide cracks and surface ripples. About 4,000 ft of 

one runway appeared to be undamaged. Part of the terminal 

building was condemned because of structural damage. Piers 

as well as railroad tracks on the piers were damaged. The 

water- and gas-distribution systems at ANAS were severely 

damaged, and both water and gas services were disrupted, 

but electric power remained available. 

POSTEARTHQUAKE OPERATIONS 

Helicopter pads remained operational and were used for 

emergency and relief operations to California Interstate Highway 880, Watsonville, Oakland, and Santa Cruz. The sixhelicopter squadron based at ANAS made 52 earthquakerelated flights. The Air National Guard also used ANAS in 

its earthquake-related activities. 

About 4,000 ft of one runway was opened 10 days after 

the earthquake for emergency purposes only and was restricted to lightly loaded aircraft. This runway was used to 

relocate many of the aircraft to the general-aviation field of 

Oakland International Airport. One runway was reopened at 

the end of December 1989, and the second was completed in 

mid-January 1990. Cracks were excavated, filled, and compacted, and the runway was resurfaced. 

ANAS was without water for 8 days and without gas 

for 2 weeks. The telephone system was saturated, and so it 

was difficult to make calls. 

WATSONVILLE AIRPORT 

Watsonville Airport has two 4,000-ft-long, lighted, paved 

runways. It is the only airfield in Santa Cruz County that is 

open to the public, serves general aviation, and is "uncontrolled," in the sense that it lacks a control tower. The airport 

has three approaches with instrument support. Both local and 

a nondirectional beacon are located at the airport, and a very 

high frequency omnidirectional ranging unit, which serves 

Watsonville Airport, operates near Salinas. 

The airport is located about 10 mi from the epicenter, and 

the peak acceleration recorded near the airport was 0.29 g. 

EARTHQUAKE DAMAGE 

Shortly after the earthquake, electrical power was lost. 

The airport did not have emergency-power generators. Aircraft there for the day could not leave because of the loss of 

runway lights. The only damage to the airport or its facilities 

was to some hangar doors, which fell from their support rails. 
PERFORMANCE OF THE BUILT ENVIRONMENT 

POSTEARTHQUAKE OPERATIONS 

Damage to highways and bridges led to the closure of 

all roads into Watsonville. California Highway 152, a mountain road with limitations on vehicle size, was reopened within 

24 hours. Watsonville Airport was used to bring relief supplies and personnel into the area. During the days after the 

earthquake, air traffic increased significantly, and the FAA 

was asked to supply a temporary control tower. On October 

19, 1989, two FAA vans established a control tower run by 

two or three people from the Monterey Airport control tower. 

Military aircraft, primarily large helicopters and C 130 transport planes, brought in personnel and heavy supplies, including water. Groups of engineers were brought in daily on 

C130's to assist in the inspection and tagging of buildings in 

the area. About 25 military flights occurred daily, and many 

flights of small private aircraft delivered clothes and food. 

Airport officials reported that 125 tons of earthquake-relief 

supplies was flown from San Jose's Reid-Hillview Airport to 

Watsonville in more than 300 flights made by light planes on 

the weekend of October 28-29. Traffic during the days after 

the earthquake peaked at several hundred flights a day. The 

FAA removed the control tower on October 24, 1989. The 

airport also added emergency-power generators. 

CONCLUSIONS AND 

RECOMMENDATIONS 

SOIL LIQUEFACTION 

The most significant impact of the earthquake on airports was the damage to the runways at Oakland International Airport and ANAS and the closing of San Francisco 

International Airport for 13 hours. None of these events interfered with or placed demands on the emergency response. 

The earthquake revealed system weaknesses, but because 

ground shaking was moderate at these sites, it did not overwhelm the systems or significantly disrupt service. 

Soil liquefaction threatens long-term disruption of airports in future earthquakes. The intensity and duration of 

ground shaking in the earthquake at airports and in other 

parts of the San Francisco-Oakland area was just above the 

threshold for liquefaction of highly susceptible soils. Liquefaction will probably recur at Oakland International Airport 

in future earthquakes that generate an equal or greater intensity and duration of ground shaking. Earthquakes of similar 

magnitude on the Hayward or San Andreas fault nearer Oakland are expected to cause much more severe and extensive 

liquefaction, both in areas that liquefied in the 1989 Loma 

Prieta earthquake and in areas not affected by the earthquake. 

SEISMIC PERFORMANCE OF 

AIRPORT CONTROL 

The emergency-response community generally assumes 

that airports will play an important role in the emergency 

response and recovery stages after a major earthquake in a 

metropolitan area. The response of city-administered parts 

of the airports performed well, with the exceptions noted 

above. The control towers did have problems. Control-tower 

windows have failed after at least four earthquakes in California: the 1971 San Fernando earthquake, the 1987 Whittier 

Narrows earthquake and its aftershock, and the 1989 Loma 

Prieta earthquake. Control-tower operations were also disrupted by fallen ceilings, light fixtures, and sound proofing. 

The 1989 Loma Prieta earthquake caused extensive, yet 

avoidable, damage to important equipment; for example, radar monitors were not anchored. This damage occurred in 

"earthquake country," caused by ground shaking considered 

moderate relative to levels anticipated for an expected great 

earthquake. In other parts of the United States, where seismic provisions are not part of the building codes, the emergency response will play an even greater role, and airports 

may be a vital element in the emergency response. During 

severe weather, which is much more common in other parts 

of the United States, the loss of control-tower windows could 

prevent a control tower from being used. The loss of function of basic monitoring equipment would almost certainly 

reduce the efficiency of airside operations. On the basis of 

California's experience, the performance of control towers 

in a severe earthquake will probably be poor. 

SEISMIC-PREPAREDNESS CHECKS 

A large airport is a combination of many complex, interdependent organizations, not unlike a moderate-size city. 

For example, 50,000 people work at Los Angeles International Airport; the airport has its own fire and police departments and a complex communication system. Airports are 

constantly evolving, with various facilities either being 

changed, upgraded, or expanded. Because of the complexity 

of their system components, as well as complex system interactions, airports should periodically conduct seismic-preparedness checks of the facility to locate and identify system 

components that might cause problems in an earthquake. Of 

particular concern are backup systems and operations, which 

are used only under unusual circumstances, such as a loss of 

commercial power. In light of the importance of backup systems and the experience after the 1989 Loma Prieta earthquake, 

it would be desirable to actually shut off the commercial power 

every few years to test how the backup-power systems and 

operations perform. Because larger airports operate around 
TRANSPORTATION SYSTEMS-AIRPORTS A109 

the clock, the timing of such a test would have to be carefully planned and coordinated with all the airport users to 

ensure that the level of disruption would be acceptable. Such 

a test would help identify potential problems in controlled 

circumstances, rather than in the aftermath of a disaster. 

DRY-TYPE TRANSFORMERS 

Dry-type transformers were damaged at two airports. 

Transformers are a component of a unit substation, which is 

a collection of power equipment that converts distribution 

voltages (2.4-21 kV) to service voltages of 480 V or less. 

The transformer can be of the dry type (the windings, which 

are exposed to the air, are contained in an electrical cabinet, 

which commonly has ventilation grates on the sides and top 

to enhance air circulation for cooling) or the wet type ,(the 

transformer windings are in a sealed tank that contains oil, 

and the tank may have radiators for enhanced cooling). Typically, the electrical cabinet is anchored to the floor slab; however, the transformer winding within the cabinet may not be 

anchored to the cabinet. Earthquake motions may cause the 

transformer winding to rock and come in contact with its 

enclosure, activating protective circuits, damaging the winding, or even causing a fire. This disruption can cause a temporary or long-term loss of power to the equipment connected 

to the unit substation. Inspection of these units can be difficult because the cabinet doors must be opened, requiring that 

electrical power to the unit be shut off. 

SPECIALIZED RECHARGEABLE BATTERIES 

Adequate supplies of specialized rechargeable batteries should be provided for critical equipment. The use of 

rechargeable flashlights and specialized battery packs for 

radios is especially common. At one site, the rack for recharging the radio batteries was not connected to the emergency power supply, and so, if the power outage had lasted 

longer, radios would have become inoperable, a situation that 

would have been a severe drawback to operations. Also, the 

flashlights were sealed units, and so standard D cells could 

not be substituted when the rechargeable cells had run down. 

At one site, two sets of radios and few spare battery packs 

were on hand. Normally, at every shift change, the incoming 

shift takes freshly recharged batteries from the charger and 

the outgoing shift inserts its batteries for recharging. After 

the earthquake, both shifts were on duty, and so most battery 

packs were being used, and few were being charged. This 

arrangement would be unacceptable in an event that required 

a longer response. 

PORTABLE RADIOS 

Airport managers should have portable radios, which 

would allow them to get an early assessment of an earthquake's 

impact and help them in initial planning. Airport managers 

and dispatchers reported that official information on the severity, extent, and impact of the earthquake was unavailable 

for several hours. If they had been equipped with a portable 

radio capable of receiving audio signals from television stations, they could have gotten the information they needed to 

determine what actions to take during the recovery. Although 

the television coverage of the 1989 Loma Prieta earthquake 

was unique, probably because of the concentration of news 

media in the area for the World Series, we can expect extensive coverage of future metropolitan earthquakes. The bias in 

media coverage to spectacular photogenic situations was clear 

in this earthquake. The failure of the San Francisco-Oakland 

Bay Bridge, the fire in the Marina District of San Francisco, 

and the collapse of the Cypress Avenue viaduct in Oakland 

dominated the news, and there were no reports about 

Watsonville for hours. Earthquake-preparedness training 

should also include cautions on the interpretation of media 

coverage. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

TRANSPORTATION SYSTEMS-SEAPORTS 

CONTENTS 

By Charles R. Farrar, Los Alamos National Laboratory; 

and 

A. Claude Griffin, Greiner, Inc. 

ABSTRACT 

There are four major commercial seaport facilities in the 

San Francisco Bay area: the Seaport of Redwood City, the 

Seaport of Richmond, the Seaport of San Francisco, and the 

Seaport of Oakland. Their primary lifeline function is to provide the initial or terminal transportation point for a variety 

of goods being imported to or exported from the San Francisco Bay area and other parts of the United States. First, we 

describe these seaport facilities, followed by a summary of 

the earthquake damage sustained, which is reported on an 

individual basis. In this summary, the seaports have been broken down into five parts: navigational channels, piers and 

wharves, cargo-handling equipment, cargo-storage areas, and 

interfaces with the inland transportation systems. The earth-, 

quake damage varied considerably for these different facilities. We discuss the steps taken to mitigate the effects of this 

damage and to bring the seaports back into operation, as well 

as the influence of the earthquake damage to other interfacing lifelines, such as power, water, natural gas, and communication systems, on the seaport operation immediately after 

the earthquake and on the long-term recovery of seaport facilities. Finally, we summarize the emergency-response plans 

that had been developed before the earthquake, their effectiveness, and the modifications to these plans that were made 

as a result of the earthquake. 

INTRODUCTION 

This section summarizes the postearthquake investigation of the major seaports in the San Francisco Bay region. 

The reconnaissance team investigated the Seaports of San 

Francisco, Richmond, and Redwood City on November 20 

and 21, 1989, and the Seaport of Oakland on November 28, 

1989. The locations of these seaports are shown in figure 1. 

Investigators attempted both to interview the engineers 

responsible for maintenance and operation of the port facilities and to inspect the actual damage to the facilities, so as to 

obtain the following information: 

Description of each seaport facility 

Description of the earthquake damage 

Description of the damage's impact on users of each seaport 

Description of the methods to restore service 

Description of obstacles to the restoration of service 

Description of the effects of earthquake damage to other 

lifelines on the operations of each seaport 

Description of the emergency plans of each seaport facility 

and their usefulness 

SEAPORT OF REDWOOD CITY 

The Seaport of Redwood City is located at the south end 

of San Francisco Bay, on the west side where Redwood Creek 

flows into the bay, as shown in Figure 1. This seaport, which 

was the one nearest the earthquake epicenter (approx 39 mi), 

is the smallest facility that was visited. A layout of this facility is shown in figure 2. Cement, scrap metal, and salt are the 

primary goods shipped from this seaport. The seaport handled 

488,000 t of freight in 1988. Tanks for petroleum products 

are also located at this seaport, along with a public marina 

and restaurants. The seaport was constructed on bay mud, 

with the wharves supported by both concrete and wood piles. 

The Seaport of Redwood City is responsible for all the maintenance of its facilities and has a one-person, inhouse maintenance crew. All the commercial wharves are accessible by 

both rail spurs and roadways. 

EARTHQUAKE DAMAGE 

Although this seaport was located closest to the epicenter 

of the earthquake, it sustained the least damage of the seaports 
A1 12 PERFORMANCE OF THE BUILT ENVIRONMENT 

in the San Francisco Bay region. Total damage was estimated 

at $260,000, consisting primarily of broken waterlines, damaged batter piles, and separation of the concrete ramp at Wharf 

1 from the pier. The seaport was never closed, and the earthquake damage had no adverse effect on the operation of the 

facility. Waterlines were repaired within a week after the 

earthquake. Other repairs to the seaport were contracted out. 

There was only a temporary interruption in electrical 

and telephone service; both services were restored within 8 

hours after the earthquake. Traffic was jammed on the major 

highways that service the seaport for most of the evening of 

the earthquake. There were no reported effects from earthquake damage to other lifelines. 

EMERGENCY-RESPONSE PLAN 

The Seaport of Redwood City had no formal emergencyresponse plan for an earthquake. When the investigation was 

made in November, 1989, the business manager said that they 

did not intend to develop such a plan at that time. 

SEAPORT OF RICHMOND 

The Seaport of Richmond is located at the northeast end 

of San Francisco Bay near the entrance to San Pablo Bay, 

approximately 65 mi from the earthquake epicenter (fig. 1). 

EPICENTER OF THE LOMA PRIETA EARTHQUAKE 

NEAR SAN JOSE 

Figure 1 .-San Francisco Bay region, showing locations of seaports. 
Figure 2.-Layout of the Seaport of Redwood City. U.S.G.S., U.S. Geological Survey. 
Ciiy-On,Â¥ne Termin~aIs 

Terminal*^). 1 For recc:ax and sh'spirient ofiyjusd b:dk corniw.-daie.i. ('.(sw.rul~ia: Cvmeu" pik. concrew- deckii wharf Gi.h rssSrtsad wwi&vvi. 

TemimaI~V-3.2 

Eq-3 by <>&&>? nia <.?ii, C.e. k>? li4@ >xiill CWX<x5 

C~~nxr-itwn: Ccncrete ~ik. cmcre~ -dediCti \\ha:f Wkh rdi;f~>;t?? <:<>3%;wticfis. 

Termha^ .%. 3 

Operated + Caiif'inria Swve<S:>f<- & Ballast d. %r steel. ~e+i>itY~. cx ~txiur~e~~zed :md di,ae~sifed 

carga5. C<.~nar';icCr.i:i; Loncrex- pk- viih .y.phais- ?<ice<$ ~wi~~ie $t:t.k ;> i?h I6 arm <~f <i<irage area. Hss state4rf-<he-art overhead i:<,ritdi!'ter hf.!i<!iÃˆi ,:<;enx 2~~ a ~~>,~B#~'%-S;:~~-$X>: hawh<>.ze j,zJt$Eg, % A.' 

Terminal No. 4 L'icti bv Pacific ?+loSassc- Co.. fates-ik Corp.. :a34 MWISWT~.SI~ c.+>. for bdi; ii~ui& C~~WW~SS 'z; 

Off-shore ?imbcr pile v.harf%'nh h&haii-pa'..'& 

Figure 3.-Layout of the Seaport of Richmond. 
TRANSPORTATION SYSTEM-SEAPORTS 

This seaport handles the most cargo (1 8 million tons per year) 

of any seaport in the San Francisco Bay region and is the 

primary seaport in the region for petroleum products and liquid bulk cargoes. Most of the terminals at the seaport are 

privately owned, and other seaport properties are leased to 

tenants under various maintenance agreements. The seaport 

facility is mapped in figure 3, along with a summary of the 

various activities, owners, and tenants at those facilities. Parts 

of the seaport are constructed on rock, and other parts on 

fill. A staff of two engineers and one maintenance person 

maintains the seaport. 

EARTHQUAKE DAMAGE 

The primary earthquake damage sustained by the Seaport of Richmond was a ruptured gasoline-storage tank at the 

Unocal terminal (Terminal 13, fig. 3). Fuel from this tank 

was contained by the surrounding berm. Some liquefaction 

occurred at the undeveloped areas on fill south of Terminal 3. 

Sand boils erupted at Terminal 3, and waterlines were broken 

at the Ford Motor Co. plant located on fill east of Terminal 3. 

Unloading of cargo was delayed for 24 hours because 

of the gasoline leak. The fire department shut off power to 

the terminals because they feared that sparks might ignite 

fumes from the spilled fuel. Also, a ship that had arrived to 

unload automobiles was sent to deep anchorage until the 

gasoline was cleaned up. The other reported damage had no 

effect on the operation of facilities at the terminals where it 

occurred. 

Because damage was sustained exclusively by privately 

owned terminals, the Seaport of Richmond was not involved 

in restoration of services. Within 48 hours after the earthquake, the entire seaport facility was functioning normally. 

There was no damage to other lifeline services. To help with 

the commuter problems that resulted from closing of the San 

Francisco-Oakland Bay Bridge, the Seaport of Richmond 

added facilities for additional ferries at Terminal 3. These 

facilities began operating on Monday, October 23; they would 

have been operating on Thursday, October 19, but a floating-dock facility had to be added because of the low freeboard of the ferries relative to freight vessels that are normally 

moored at this terminal. Before the San Francisco-Oakland 

Bay Bridge was reopened, the new ferry service transported 

400 to 500 passengers a day on the 45-minute, 8-mi trip to 

the Ferry Building at the Seaport of San Francisco. 

EMERGENCY-RESPONSE PLAN 

Engineers at the Seaport of Richmond stated that they 

had no emergency-response plans for earthquakes, because 

the seaport is under the jurisdiction of the City of Richmond 

and the city has charged the fire department with emergency 

response. 

SEAPORT OF SAN FRANCISCO 

The Seaport of San Francisco extends for 7 mi along the 

west side of San Francisco Bay, from west of Aquatic Park to 

India Basin (fig. 1). The seaport is located approximately 60 

mi from the earthquake epicenter. Activities at this seaport 

are diverse and include import and export of general cargo, 

primarily in container form, ship repair, passenger and cruise 

ships, a fishing industry, and tourist attractions. A total of 3 

million t of general cargo pass through this seaport annually. 

Annual revenues from the seaport in 1988 were estimated at 

$38 million. Figure 4 shows that most of the San Francisco 

waterfront is constructed on fill. Most of the seaport is constructed on fill behind seawalls; the parts of the piers extending past the seawalls are supported on piles of concrete, timber, 

or concrete-encased timber. The central parts of the piers were 

built on fill to accommodate rail spurs, but today the piers are 

served primarily by trucks. The Seaport of San Francisco has 

an 11-person engineering staff, 4 inspectors, and a maintenance crew of approximately 70 people. 

EARTHQUAKE DAMAGE 

At the time of the investigation in 1989, engineers at the 

seaport estimate that repairs of earthquake-related damage 

would cost $8 million to $10 million. Tenants sustained additional damage, for which the seaport is not responsible. As 

with the other seaports in the San Francisco Bay region, the 

tenants' responsibility for repair and maintenance of their facilities differs under different lease agreements. The primary 

cause of damage was liquefaction of the fill materials, which 

resulted in settlement of the parts of the piers supported by 

fill relative to those supported by piles. Settlement continued 

for several weeks after the earthquake. Sand boils erupted at 

Pier 45 (sand boils result from the upward flow of water caused 

by the excess pore-water pressure associated with liquefaction). Because of significant structural damage at different 

places along the waterfront, some buildings were condemned. 

Structural damage included cracked concrete walls and displaced asphalt decks in the warehouses on Piers 45 and 48, 

caused by settlement of the underlying fill; cracking and collapse of unreinforced clay-tile walls in an office building on 

Pier 70; and buckling of columns in the clock tower above 

the Ferry Building, where the offices for the Seaport of San 

Francisco are located. The Agriculture Building adjacent to 

the Ferry Building was closed because of differential settlement. Other damage at the seaport included many broken waterlines, many broken batter piles, cracked concrete decks 

above piers, and damage to five container cranes. 

Significant damage was sustained by the 17-story clock 

tower above the Ferry Building, but this damage had only a 

limited effect on the operation of the seaport. Both the clock 

tower and the Ferry Building had survived the 1906 San Francisco earthquake. The clock tower's primary structural ele- 
Figure 4.-Seaport of San Francisco and landfill areas. 
TRANSPORTATION SYSTEM-SEAPORTS A1 17 

ments are four laced columns, each of which consists of two 

channel sections tied together with riveted plate laces on either 

side. Diagonal tie rods with turnbuckles are used to provide 

lateral stability. At the 13th level, two of the columns had buckled. The damaged sections were cut out, and temporary splices 

were added. At several levels, the tie rods were noticeably deformed, but without knowing their previous condition, it was 

difficult to determine whether the earthquake caused this deformation. 

Commercial freight operations at the Seaport of San Francisco were largely unaffected by the earthquake damage. Two 

damaged container cranes were jacked back onto their rails, 

and a contractor replaced the damaged steel plates on the cranes' 

legs. Meanwhile, standby cranes were brought into service, and 

ships were being unloaded by Thursday, October 19. Commercial fishing was probably the most adversely affected business 

because two warehouses located on Pier 45 that were used for 

transportation and processing of fish were closed as a result of 

earthquake damage. Grain elevators near the south container 

terminal had to be closed until damage to a drag-conveyor bridge 

structure could be repaired. The Seaport of San Francisco lost 

revenue from businesses in the tourist sections of the seaport, 

which, as part of the lease agreements, pay the seaport a percentage of their profits. At the time of this investigation, a month 

after the earthquake, these businesses continued to have reduced 

tourism as a result of the earthquake. 

Waterlines and gaslines were repaired within a week after 

the earthquake. The Seaport of San Francisco did not have 

enough plumbers to accomplish the repairs that fast, and so additional plumbers were provided by a private contractor and by 

the City of San Francisco. Temporary repairs to the differential 

settlement problems were handled by constructing asphalt ramps 

over cracks in the existing pavement. Inhouse maintenance 

people did these repairs, and there was no difficulty in obtaining repair material. Offices in buildings that sustained significant structural damage were moved to other locations. Fish 

processing, which was normally handled in a warehouse on Pier 

45, was moved to Pier 33. 

Telephone service was never lost at the Ferry Building, 

but the lines were jammed because of the volume of calls. Loss 

of electrical power to Pier 45 caused problems for the fish-processing businesses, which had to rent generators to prevent thawing of their freezers. The Pacific Gas & Electric Co. (PG&E) 

had turned off commercial power because of a concern that gas 

leaks might cause fires. Electrical power was restored by 2:00 

p.m. P.s.t. October 19. Damage to the San Francisco-Oakland 

Bay Bridge resulted in an increased use of ferries by commuters, and additional temporary ferry terminals were set up at Pier 

1. These terminals began operating on Monday, October 23. 

EMERGENCY-RESPONSE PLANS 

A month after the earthquake, the engineers at the Seaport of San Francisco stated that they had no formal emergency-response plans for earthquakes. The citywide emergency-response plan includes the seaport. As a result of the 

1989 Loma Prieta earthquake, utility-shutoff manuals have been 

distributed to maintenance personnel and local fire stations. 

The fireboat Phoenix, which is under the jurisdiction of 

the seaport (and which the City of San Francisco had previously been planning to put out of service as a cost-saving 

measure) was instrumental in putting out the fires in the Marina District. 

SEAPORT OF OAKLAND 

The Seaport of Oakland occupies 19 mi of shoreline on 

the east side of San Francisco Bay (fig. 1). The seaport is 

located approximately 55 mi from the earthquake epicenter. 

A detailed layout of the seaport is shown in figure 5. Both 

Oakland International Airport and the seaport are under the 

jurisdiction of the Port of Oakland; however, this section focuses exclusively on the seaport. Container freight is the primary item handled by this seaport. At the time of the 

earthquake, the seaport had 25 container cranes, which handle 

14 million t of cargo annually. Most of the seaport is constructed on fill behind dikes of sand and rock, with pile-supported wharves over the dike faces. All of the terminals are 

served by rail spurs and trucks. Some terminals are leased to 

private concerns with varying maintenance agreements; others are used as needed by customers, with the seaport providing the maintenance. A 25-person engineering staff and a 

70-person maintenance crew maintain the seaport. 

EARTHQUAKE DAMAGE 

Initially, earthquake damage at the Seaport of Oakland 

was estimated at $75 million. Damage occurred primarily at 

the Seventh Street Complex and the Middle Harbor; the Inner and Outer Harbors were relatively undamaged. As at the 

Seaport of San Francisco, the primary cause of damage was 

liquefaction of the fill and the resulting settlement and spreading of areas on fill relative to areas supported by piles. The 

many broken waterlines and fire lines washed the fine material from the soil, causing both settlement and uplift of the 

asphalt pavement at numerous places throughout the seaport. 

Concrete batter piles were broken at the Seventh Street Complex terminals and at the Matson Terminal; a cross section of 

these terminals is shown in figure 6. The piles support a concrete deck covered by 3 ft of sand through which utility lines 

run; 3 in. of asphalt pavement covers the sand. The damage 

to piles at this terminal resulted from the inertial forces generated by the large mass supported on top of these piles. A 

horizontal ground acceleration of 0.29 g and a vertical ground 

acceleration of 0.07 g were measured at Terminal 25 of the 

Outer Harbor; a horizontal acceleration of 0.45 g was measured on the wharf at Terminal 25. Wood piles with concrete 
A1 18 PERFORMANCE OF THE BUILT ENVIRONMENT 

followers were broken at the Middle Harbor, resulting in 

condemnation of a building that was supported on these piles; 

the piles broke at the wood-concrete interface. Throughout 

the seaport? damage to the piles and settlements of the fills 

were discovered over a period of 1 year after the earthquake. 

A container crane derailed at the Middle Harbor? and the 

100-ft gauge distance between the rails increased as much 

as 4 in. A total of 23 container cranes sustained damage estimated at $5007000. At the Seventh Street terminals? the crane 

rails that were on fill settled as much as 12 to 15 in. relative 

to the crane rail on piles? making the container cranes inoperable. The rail spur serving Terminal 40 was out of service 

because of horizontal and vertical displacement of the rails 

on fill relative to the part of the spur supported by piles. Significant settlement and separation of the truck-access road 

to Terminals 35 through 38 at the Seventh Street Complex 

occurred as a result of liquefaction. 

The Seventh Street Complex was shut down. Half of 

the complex was temporarily repaired and back in service 

by March 1990; permanent repairs to the other half were 

CITY 

0 F 

OAKLAND 

PORT 

FACILITIES 

ATSON TERMINAL 

OAKLAND INNER HARBOR CHANNEL 

1 

Figure 5.-Seaport of Oakland and facilities. 

TYPICAL SECTION 

SEVENTH STREET TERMINAL BERTHS: 35 TO 3e 40 DWGS AA-1023, AA-I042 

SCALE la'= 300' DATE: JUNE, I967 

Figure 6,-Typical cross section of the Seventh Street Terminal at the Seaport of Oakland. 
TRANSPORTATION SYSTEM-SEAPORTS A1 19 

completed by June 199 1. Except for the crane at the Middle 

Harbor that derailed and the cranes on the damaged rails at 

the Seventh Street Terminal? all other container cranes remained operable. The derailed crane was repaired and operable within a day after the earthquake despite the increased 

gauge length of the rails. Although settlement and uplift of 

the pavement occurred throughout the staging areas for container freight, this damage did not hinder the overall operation of these facilities. 

Repairs to the seaport were done by outside contractors. Temporary repairs consisted of placing asphalt at the 

locations of large discontinuities in the pavement. Waterlines 

for which the seaport was responsible were repaired within 

2 weeks; waterlines maintained by the City of Oakland were 

repaired within a week after the earthquake. Permanent repairs to the crane rails at the Seventh Street Complex entailed 

the removal of the settled crane rail originally constructed on a 

grade beam supported by fill. This rail was replaced by a rail 

supported by a beam on piles and tied into the wharf to provide further earthquake resistance. The Matson Terminal? 

which does its own maintenance? appeared to be replacing 

the pavement on most of its property. 

Damage to other lifelines had no direct impact on the 

Seaport of Oakland. Electrical power was lost temporarily? 

but there were no problems with gaslines. Fire lines ruptured, 

but no fires were reported? and so this damage did not adversely affect the seaport. One obstacle to repair of the seaport is the absence of reliable bench marks for surveying. 

Because the bench marks were determined to have moved as 

a result of the earthquake? a level circuit was brought in from 

remote sites not disturbed by the ground motion. 

EMERGENCY-RESPONSE PLANS 

The seaport had no formal emergency-response plan for 

earthquake damage? but it did have an emergency procedure 

and call lists of contractors and equipment suppliers. A formal emergency response manual is now in place and undergoing its second revision. 

CONCLUSIONS 

Extensive earthquake damage to seaport facilities can 

be expected from settlement and soil liquefaction.-Seaports 

in the San Francisco Bay region were constructed before 

modern engineered-fill procedures were in use, and so the 

1989 Loma Prieta earthquake caused extensive damage from 

differential settlement and soil liquefaction. Much more extensive and severe problems can be expected in future earthquakes if ground motions are more severe or last longer. 

The use of diflerent foundation types within a given structure increases the potential for earthquake damage.-Differential settlement of pile-supported parts of the terminal relative 

to the parts supported by fill caused structural damage to buildings and equipment that straddle the different foundation systems. Container cranes and their rails are particularly 

susceptible to damage from differential settlement. Future 

seaport designs should have a consistent foundation system 

under a structure? and structures should not be supported directly on fill or be founded on fill. 

Damage to piles can be reduced by avoiding terminal 

designs that place excessive mass on top of the piles.-The 

batter piles under Terminal 40 at the Seaport of Oakland, 

which support a 3-ft-thick layer of sand on top of a concrete 

slab? were severely damaged. This damage could possibly 

have been mitigated if an alternative method of running utility lines was developed that did not require the sand layer, 

thus reducing the mass (and inertial forces) supported by the 

piles. 

Improved planning should reduce damage in future 

earthquakes.-The Seaport of San Francisco's plan to distribute utility-shutoff manuals to maintenance personnel and 

local fire stations is an inexpensive precaution that could prevent additional damage immediately after future earthquakes. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

TRANSPORTATION SYSTEMS-PASSENGER RAILWAYS AND BUSLINES 

By Stuart D. Werner? Seismic Systems & Engineering Consultants; 

and 

Anshel J. Schiff? Precision Measurement Instruments and Stanford University 

CONTENTS 

ABSTRACT 

This paper describes the effects of the earthquake on the 

following vital railways and (or) buslines in the San Francisco Bay region: the Bay Area Rapid Transit (BART) system? the San Francisco Municipal Railway (Muni), and 

Caltrain. The BART and Caltrain systems are rail based? and 

the Muni system includes both railways and bus7 trolleys7 

streetcars? and cable cars. For each system, we provide an 

overview and describe the earthquake damage? the immediate postearthquake operations? and the operations during the 

recovery period. All of these systems were nearly undamaged; the primary disruptions to the systems were for 

postearthquake inspection (for several hours after the earthquake) and a loss of electrical power. 

INTRODUCTION 

Three rail-based transportation systems have been investigated in the earthquake-affected area: the Bay Area 

Rapid Transit (BART)? the San Francisco Municipal Railway (Muni)? and Caltrain. The Muni system includes buses? 

trolleys7 streetcars? and cable cars. 

BAY AREA RAPID TRANSIT 

Since the early 1 9707s7 the BART system has provided 

a vital rail-transportation link for the east bay and the city of 

San Francisco. The system consists of three lines: (1) a single 

line that serves San Francisco and extends from Daly City in 

the south to the Embarcadero area of downtown San Francisco; (2) two single-bore transbay tubes along the bottom of 

San Francisco Bay that connect San Francisco to Oakland 

and the east bay; and (3) three separate lines in the east bay 

that branch from Oakland and extend northward to Richmond? 

southward to Fremont? and eastward to Concord. The BART 

system contains 71.5 mi of track and 34 stations? which are 

equally divided between elevated? surface? and subway sections. The system is served by 570 cars? which are self-propelled from 1-kV d-c power provided over a third rail. Three 

facilities in the east bay provide operational maintenance for 

these cars; in addition, a new facility in Daly City was opened 

shortly after the earthquake. 

The Pacific Gas & Electric Co. (PG&E) provides traction power for the operation of BART trains and conventional 

power for station operations? lighting, and communications. 

The traction power is obtained from PG&E through seven 

special substations that are distributed throughout the BART 

system. These substations have PG&E transformers that convert 115-kV to 34.5-kV power; BART7s power-distribution system distributes this 34.5-kV a-c power to 34 locations7 where it 

is converted to 1-kV d-c power and then supplied to the rails. 

Power for BART station operations? lighting? and communications comes from PG&E7s regular power-distribution system. Batteries provide backup power for station lighting. 

BART has earthquake alarms along its track routes that 

alert BART'S central-operations facility when ground shaking exceeds 0.1 g. Central operations then notifies the train 

operators by radio? and the trains are either stopped? if they 

are in a station? or directed to proceed at a slow speed to the 

next station, where the passengers are unloaded. 

EARTHQUAKE DAMAGE 

Although no significant structural damage was reported 

anywhere in the BART system? some minor damage did occur 

in the transition structure between the transbay tubes and the 

West Oakland Station? and at several stations in the east bay. 

The transbay tubes sustained minor water seepage but no structural damage. In San Francisco7 the most serious problem resulted from the loss of electrical power to sump pumps that 
A122 PERFORMANCE OF THE BUILT ENVIRONMENT 

are routinely used to remove water which enters the subway 

between the Civic Center and Powell Street Stations in downtown San Francisco, from an underground stream at that site. 

Because of the power outage, water began to fill the sump at 

the Powell Street Station. The water rose to within 2 in. of the 

top of the rails before generators were obtained from the San 

Francisco Department of Public Works to operate the pumps. 

IMMEDIATE POSTEARTHQUAKE OPERATIONS 

Immediately after the earthquake, electrical power was 

lost in San Francisco to one of the seven PG&E feeds that 

supply BART with traction power for its trains. Power was 

also lost to several stations in San Francisco. 

The loss of traction power affected the trains in San Francisco that were between stations at the time of the earthquake, 

as well as trains in the transbay tubes. Limited traction power 

for trains in downtown San Francisco was transmitted from 

the east bay through the third rail, enabling BART to slowly 

move one train at a time to the next station, where the passengers could disembark. However? passengers on one train near 

the Powell Street Station in downtown San Francisco had to 

exit through the tunnel to the station. 

Eastbound trains in the transbay tube and trains in the 

east bay and in San Francisco south of the downtown area 

were able to proceed to the next station. However, a single 

train in the transbay tube was heading westbound into San 

Francisco at the time of the earthquake. This train was stopped 

in the tube for about 20 minutes, until trains at the 

Embarcadero Station in San Francisco (the station closest to 

the west end of the tube) could be repositioned. After this 

repositioning, the train proceeded through the tube to the station, where its passengers disembarked. 

Emergency batteries prevented the BART stations in San 

Francisco that lost their primary PG&E power from going 

dark. Temporary power outages occurred at the Coliseum and 

Fremont Stations in the east bay, and radio communication to 

some of the trains was briefly lost. However? BART'S train 

operators have backup mobile radios? which they used until 

normal communication was restored. 

BART officials reported that all passengers in San Francisco were unloaded from the trains within about 30 minutes 

after the earthquake. BART'S earthquake-alarm system functioned properly, although it was superfluous because personnel in BART'S central-operations facility felt the shaking and 

were aware that a major earthquake had occurred. After evacuating all passengers, BART was shut down because of the 

power outage and the need to inspect the system for earthquake damage. 

Traction power was restored at the damaged San Francisco BART substation about 4% hours after the earthquake, 

allowing trains to operate and speeding inspection. Electrical 

power to stations was restored about 6 hours after the earthquake. Limited train service started at about 2100 a.m. P.s.~. 

October 18 and gradually increased as various BART lines 

and stations were returned to service. Normal rush-hour service was started at about 5100 a.m., and all stations were reported to be operating by 8:30 a.m. 

OPERATIONS DURING 

THE RECOVERY PERIOD 

Until the damaged San Francisco-Oakland Bay Bridge 

was reopened on November 17, 1989, BART and a transbay 

ferry system that was initiated after the earthquake were the 

only direct modes of transportation between the east bay and 

San Francisco. To meet its increased transportation demands 

during this period, BART initiated 24-hour daily service. 

BART'S daily ridership soon increased from a preearthquake 

level of 218,000 passengers to a postearthquake peak of 

357,000 passengers-a 64-percent increase. This substantially 

increased demand began to overload BART'S existing maintenance facilities, temporarily leading to less frequent and 

shorter trains. To alleviate this problem, BART accelerated 

the start of operations at a new maintenance facility in Daly 

City, and the maintenance backlog was soon reduced. 

Since the reopening of the San Francisco-Oakland Bay 

Bridge, BART'S daily ridership has stabilized at a level that 

is about 20 percent greater than its preearthquake ridership. 

Therefore, although its 24-hour service has been discontinued, BART7s weekday service now begins 1 hour earlier than 

it did before the earthquake, and its rush-hour schedule has 

been extended for an extra hour each afternoon. In addition, 

26 additional cars and two additional train sets operate during each peak period. 

SAN FRANCISCO MUNICIPAL RAILWAY 

The Muni system serves San Francisco with several different types of transportation systems, including light-rail 

trains? trolleys, cable cars? electric-powered buses, and diesel-powered buses. The system has 78 routes throughout the 

city, which are served by 540 diesel buses, 345 trolleys, 12 

streetcars, 130 light-rail vehicles, and 37 cable cars. 

Muni relies on PG&E9s electrical power for propulsion 

of its trains? operation of its stations, and operation of signal 

lights in its underground tunnels. Should power be lost? Muni 

has no backup power for these vital functions. Emergency 

diesel generators are available only for the Metrocom radios 

and the data-acquisition computers in Muni's central-control 

facility. Emergency lighting for this facility is provided by a 

battery-powered backup system. 

EARTHQUAKE DAMAGE 

The earthquake did not directly damage Muni's facilities, its overhead power-distribution system? or its tracks. The 
TRANSPORTATION SYSTEMS-PASSENGER RAILWAYS AND BUSLINES A123 

only significant damage to Muni's physical plant occurred in 

a pre-1906 building that was of secondary importance to 

Muni's overall operations. 

system is 47 mi long, has 24 stops, and is served by 20 diesel 

locomotives and 73 cars. 

EARTHQUAKE DAMAGE 

IMMEDIATE POSTEARTHQUAKE OPERATIONS 

All of Muni's electric-powered vehicles (its trolleys, 

light-rail trains, cable cars, and electric-powered buses) were 

unable to function because of the power outage in the downtown San Francisco area immediately after the earthquake. 

Also, because of Muni's lack of backup power, its station 

power and signal lights in the downtown area went out. Several trains were stranded in tunnels and underground stations, 

and passengers had to be evacuated by train crews, station 

agents, and available supervisors and managers, with flashlights providing the only source of lighting. The evacuation 

was completed within about 45 minutes, probably because 

the trains happened to be near stations at the time of the earthquake. 

Except for the power outage, no disruptions to Muni operations after the earthquake, and no injuries or accidents were 

reported. In addition, backup-power generators that operated 

fuel pumps at the Wood's Diesel Division parking and service area allowed diesel-powered buses to continue operating. 

Diesel and gasoline fuels were also provided to other city 

vehicles until power was restored by PG&E. 

OPERATIONS DURING 

THE RECOVERY PERIOD 

About 60 percent of Muni's service was restored within 

1 day after the earthquake. Passengers who normally used 

Muni's electrical-powered buslines to downtown San Francisco rode to stations outside of the downtown area, where 

they had to transfer to diesel-powered buses that continued to 

downtown destinations. Commercial power was fully restored 

2 days after the earthquake, when all of Muni's normal operations resumed. Muni modified its normal bus routes to accommodate passengers who used ferryboats to commute to 

San Francisco from the east bay. 

Muni did not sustain major financial losses due to the 

earthquake. Costs to repair earthquake damage were minimal, and revenue losses due to decreased ridership immediately after the earthquake were at least partly counterbalanced 

by (1) the use of monthly passes by about 60 percent of its 

normal passengers and (2) additional passengers coming in 

from the ferries. 

CALTRAIN 

Caltrain runs commuter trains on the Southern Pacific 

Railroad tracks between San Jose and San Francisco. The 

No significant damage to the Caltrain system was reported; minor damage consisted of a few fallen bricks from 

one of the tunnel linings. The tracks south of San Jose, which 

are not part of the commuter-train rail system, buckled and 

were repaired within 2 days after the earthquake. 

IMMEDIATE POSTEARTHQUAKE OPERATIONS 

In accordance with Caltrain's policy for earthquakes of 

4425.0, a11 trains in operation during the earthquake proceeded 

slowly to the next station, where all passengers disembarked. 

The Caltrain system was then shut down for inspection, also 

in accordance with Caltrain's earthquake policy. This inspection was completed within 5 hours, and service was resumed 

at about 1O:OO p.m. on the night of the earthquake. 

When Caltrain trains resumed operation after the earthquake, they maintained a maximum speed of 20 mi/h because 

of the possibility of aftershocks. In addition, train schedules 

were reduced because many of Caltrain's crew members live 

in Santa Cruz, where damage to roads prevented them from 

reporting to work. 

OPERATIONS DURING THE RECOVERY PERIOD 

During the week after the earthquake, Caltrain's daily 

ridership rose to a level 32 percent above preearthquake ridership. By early December, ridership stabilized somewhat but 

was still 10 percent higher than preearthquake levels. Caltrain 

added more cars to its scheduled trains to accommodate this 

increased ridership but added no new trains. 

On October 23, 1989 (6 days after the earthquake), 

Caltrain began an emergency rail service south of San Jose, 

primarily to serve the Watsonville area. This service was terminated on November 10 because of a dispute between the 

State of California and the Southern Pacific Railroad over 

liability and insurance. 

CONCLUSIONS 

Almost no earthquake damage to any of the rail systems in the San Francisco Bay region was reported, although 

all the systems discontinued service for several hours after 

the earthquake to inspect for earthquake damage. The primary disruption of the BART and Muni systems was due to 

a power outage in San Francisco. The most significant disruption to Caltrain service after the earthquake was caused 
A124 PERFORMANCE OF THE BUILT ENVIRONMENT 

by the unavailability of crew members who lived in the 

stricken Santa Cruz area. 

The importance of the BART system as a vital transportation link between San Francisco and the East Bay was demonstrated in this earthquake. Accordingly, we note the absence of 

any strong-motion-recording instruments within the transbay 

tubes. Although such instrumentation would not affect the performance or safety of the system, it would be invaluable for 

measuring characteristics of the motions in the tubes. Such 

measurements would be particularly helpful in interpreting any 

damage to the tubes that might occur during future earthquakes. 

The BART system was particularly instrumental in 

meeting the increased transportation needs caused by the 

closing of the San Francisco-Oakland Bay Bridge. Muni and 

Caltrain played major roles in alleviating problems caused 

by the closing of elevated highways in San Francisco. 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

RESIDENTIAL NATURAL-GAS PIPING AND APPLIANCES 

CONTENTS 

By Peter W. McDonough, Questar Corp. 

ABSTRACT 

This paper summarizes the results of questionnaires on 

the types of natural-gas-related damage reported in homes in 

Los Gatos, Cupertino, and Mountain View after the earthquake. These data may be useful in predicting the performance 

of typical residential gas piping and appliances during moderate (modified Mercalli intensity VII) earthquakes. 

INTRODUCTION 

In response to the earthquake, the Mountain Fuel Supply Co., a subsidiary of Questar Corp. of Salt Lake City, Utah, 

sent 3 1 Customer Service Department personnel to assist 

Pacific Gas and Electric Co. employees in reestablishing natural-gas service in the San Francisco Bay region. Upon their 

return, Mountain Fuel Supply Co. personnel were asked to 

complete a short questionnaire (see appendix) on the basis of 

recollection of their observations. Realizing that these employees had not taken notes (they were working 16 days) and 

were not expecting to be asked detailed questions about their 

work, we requested that they simply answer, to their best recollection, in terms of percentages. The questions center around 

residential structures where gas service was cut off because 

of service valves (identified as "fire cocks" in the questionnaire) being shut. The survey did not evaluate destroyed structures, which the employees would not have been asked to 

visit. Building age ("old" versus "new") was addressed, as 

well as the type of damage observed. Because of the possible 

significance of seismic shutoff valves, four of the eight questions deal with these valves. Mountain Fuel Supply Co. personnel worked in three communities west of San Jose: Los 

Gatos, Mountain View, and Cupertino (fig. 1). Separate questionnaires were provided for each town. Of approximately 

18,000 customers without gas in these areas, about 15 percent of total area customers, Mountain Fuel Supply Co. personnel visited approximately 4,500. A total of 22 completed 

questionnaires were returned, providing a sample of approximately 18 percent of affected customers. 

An isoseismal map of the San Francisco Bay region is 

shown in figure 1. 

SURVEY RESULTS 

The results of the questionnaire are summarized in table 

1. Significant observation about these results include the following: 

1. In approximately 21 percent of the buildings where 

service valves had been closed, some type of downstream 

gas-pipelappliance damage was reported, with no significant 

influence by recorded differences in ground acceleration of 

0.21 to 0.53 g. 

2. Only in Los Gatos (fig. I), where a modified Mercalli 

intensity (MMI) of VII was assigned, was most of the damage in old (approx pre- 1950) buildings. The fact that damage 

was reported in a significant percentage of newer buildings 

in all three communities implies that gas-facility damage was 

largely independent of the greater structural damage anticipated in older buildings. 

3. The most common type of damage observed was to 

unattached vent ducting. Although this damage would cause 

combustion products to enter the structure, it does not imply 

gas leakage. This and the second-most-common problem, water-heater movement, were also probably the easiest to mitigate (that is, provide adequate strapping of water heaters; use 

sheet-metal screws to attach sections of vent duct). Damage 

to piping not associated with water heaters was observed in 

no more than 9 percent of the buildings visited. 

4. Natural-gas-caused fire damage was observed in no 

more than 1 percent of the buildings visited. These fires can 

be assumed to have been minor because the buildings continued to be occupied after the earthquake. 

5. Very few earthquake shutoff valves were observed, 
PERFORMANCE OF THE BUILT ENVIRONMENT 

Table 1 .-Summary of survey results on buildings with service valves closed. 

[All values in percent, except as noted. See figure 1 for locations] 

Los Gatos Cupertino Mountain View 

Buildings with pipelappliance damage--------- 22 

Buildings with pipelappliance damage 57 

that were classed as "old." 

Damaged buildings with: Damaged water heaters ...................... 44 

Damaged vent piping ........................ 58 

Damaged furnaces ........................... 13 

Damaged ranges .............................. 1 

Damaged meter sets/outdoor piping ------- 5 

Damaged interior piping 4 

Damage-related fires .................... ---- - < 1 

Undamaged buildings with activated <1 

earthquake valves. 

Damaged buildings with activated 0 

earthquake valves. 

Damaged buildings with unactivated 0 

earthquake valves. 

Activated earthquake valves that could 0 

not be reset. 

Modified Mercalli intensity ...................... VII 

Local peak ground accelerations at sites 0.53, 0.33 

in each city (g). 

24 

44 

38 

67 

15 

<1 

4 

7 

1 

0 

0 

0 

0 

VII 

0.53, 0.33, 

0.22 

16 

40 

4 1 

57 

11 

<1 

4 

9 

0 

1 

6 

0 

2 

VII 

0.38, 0.22, 

0.21 

which apparently were activated from the ground accelerations of 20.21 g that were recorded. 

CONCLUSION 

These survey data may be useful in predicting the performance of typical residential gas piping and appliances 

during MMI VII shaking. Comparable epicentral intensities 

might be expected during moderate (M-5.5) earthquakes. 

These data also may point out where the most practical damage mitigation can be undertaken by homeowners. 

The survey result showing that approximately 21 percent of the buildings with valves closed actually were damaged can also be read as that 79 percent of the buildings had 

valves which closed needlessly. 

REFERENCES CITED 

Boore, D.M., Seekins, Linda, and Joyner, W.B., 1989, Peak accelerations from the 17 October 1989 Loma Prieta earthquake: 

Seismological Research Letters, v. 60, no. 4, p. 151-166. 

Stover, C.W., Reagor, B.G., Baldwin, F.W., and Brewer, L.R., 1990, 

Preliminary isoseismal map for the Santa Cruz (Loma Prieta), 

California, earthquake of October 18, 1989 UTC: U.S. Geological Survey Open-File Report 90-1 8,24 p. 
RESIDENTIAL NATURAL-GAS PIPING AND APPLIANCES 

-J 

'A. 

-. - 

7. - 

F 

EXPLANATION 

Epicenter 

8 Felt at intensity 8 

Figure 1 .-San Francisco Bay region, showing locations of water- and wastewater-treatment plants and areas of modified Mercalli intensity 

(roman numerals). EBMUD, East Bay Municipal Utility District. From Stover and others (1990). 
PERFORMANCE OF THE BUILT ENVIRONMENT 

APPENDIX: QUESTIONNAIRE ON OBSERVATIONS OF THE 

EARTHQUAKE PERFORMANCE OF NATURAL-GAS PIPING AND 

APPLIANCES IN THE SAN FRANCISCO BAY REGION 

Town: 

(Please give the best-estimate answer based on the buildings you personally visited.) 

1. Of the buildings you found with fire cocks turned off, what percentage had some type of gas-pipelappliance damage? 

2. Of the buildings you found with gas-pipelappliance damage, 

what percentage would you classify as old (built before 1950)? 

3. Of the buildings with gas-pipelappliance damage, what percentage had damaged water heaters? 

vents? 

furnaces? 

ranges? 

meter sets or adjacent outdoor piping? 

interior piping? 

4. What percentage of the gas-related damage that you observed 

resulted in fires? 

5. What percent of the buildings without pipelappliance damage 

had earthquake valves that activated? 

6. What percentage of the buildings with pipelappliance damage 

had earthquake valves that activated? 

7. What percentage of the buildings with pipelappliance damage 

had earthquake valves that did not activate? 

8. What percentage of the buildings with earthquake valves that 

activated had earthquake valves that could not be reset? 
THE LOMA PRIETA, CALIFORNIA, EARTHQUAKE OF OCTOBER 17,1989: 

PERFORMANCE OF THE BUILT ENVIRONMENT 

LIFELINES 

REPAIR PATTERNS FOR THE GAS-DISTRIBUTION SYSTEM 

IN SAN FRANCISCO 

CONTENTS 

By Douglas G. Honegger, Consultant 

Page 

A129 

129 

129 

131 

131 

132 

132 

133 

133 

133 

ABSTRACT 

Leak-repair calls in San Francisco were tracked imrnediately after the earthquake. This information was subsequently 

obtained from the Pacific Gas & Electric Co. and examined 

for possible correlation with other geologic, seismic, and structural information. Repair data were mapped with recorded 

peak ground acceleration, modified Mercalli intensity, building damage, near-surface soil types, and sites of liquefaction. 

Although the results obtained from this type of data representation are qualitative, they provide a convenient format 

for analyzing the various types of information. The maps indicate that soil characteristics are the best indication of where 

damage to the gas-distribution system can be expected in future earthquakes. 

INTRODUCTION 

After the earthquake, considerable interest was focused 

on the relatively small Marina District of San Francisco and 

on the damage sustained by the gas-distribution system there. 

However, virtually no detailed repair data are available on 

this system because the system was largely replaced in the 

weeks after the earthquake. Low-pressure steel and cast-iron 

gas-distribution lines were inserted with plastic lines operating at higher pressure. This paper presents other gas-distribution-system damage in the city of San Francisco for which 

considerable information is available. Damage to the gasdistribution system in San Francisco was light, even including the loss of gas service in the Marina District, an 

observation consistent with earthquake magnitude and epicentral distance. Examination of data for the entire city is 

more useful for identifying regional weak spots in the system that may be important in the event of future large earthquakes. The data collected after the earthquake included 

leak-repair address, pipe material, and type of repair. 

The data presented in this paper are in the form of various maps generated for the San Francisco area. The maps 

indicate the locations of grade I leak repairs performed by 

the Pacific Gas and Electric Co. (PG&E) in the San Francisco Division of the Golden Gate Region; grade I leaks are 

indicated by the presence of a noticeable gas odor. 

GRADE I LEAK REPORT DATA 

Tracking of earthquake-related grade I leak repairs was 

accomplished by assigning a special billing account. PG&E 

uses a standard leak-repair-reporting form; information is 

tracked by a computerized data base. PG&E provided a summary of the leak-repair data base for their San Francisco Division for the period October 17-31, 1990. These data were 

incorporated into a data base and mapped to show the repair 

locations along with key site data. This data base is unusual 

in that no differentiation was made regarding existing damage from corrosion or other preexisting conditions. Gas-distribution systems typically have many existing leak conditions 

that are less serious and may not be readily locatable. Repair 

of these low-grade leaks is generally handled as a part of 

routine maintenance. Earthquakes can increase the rate of 

leakage at the locations of lower-grade leaks. 

Leak-repair data are tracked according to the mapping 

grid established by PG&E for the city of San Francisco. A 

standard plat reference scheme is used to refer to detailed 

system maps. Each rectangular plat map represents an area 

of 0.067 mi2, with a north-south length of 1,700 ft and an 
PERFORMANCE OF THE BUILT ENVIRONMENT 

Table 1 .-Summary of grade I leak repairs by material and function. 

Mains Service connections 

Pipe 

material Number Percentage Number Percentage of repairs of total of repairs of total 

Table 2.-Summary of grade I leak repairs by material and repair code. 

Pipe material Repair Total Percentage 

code Steel Cast iron Copper Plastic 

Bell-joint damage--------- Weld repair ---------------- 

Replace pipe section------ 

New clamp ---------------- 

Tighten clamp ------------- 

Tighten pipe joint--------- 

Pipe-body damage-------- 

Other (permanent) -------- Other (temporary) -------- 

Figure 1.-Northern part of San Francisco, showing correlation of grade I leak repairs with surficial deposits and recorded ground motions. CDMG, California Division of Mines and Geology; PGA, peak ground acceleration; USGS, U.S. 

Geological Survey. 
REPAIR PATTERNS FOR THE GAS-DISTRIBUTION SYSTEM IN SAN FRANCISCO A131 

east-west length of 1,100 ft. San Francisco city and County 

are covered by a total of 194 plat maps. 

Site data mapped with the leak locations provided by 

PG&E include recorded peak ground acceleration (Maley 

and others, 1989, Shakal, 1989), surficial soil deposits, building damage, modified Mercalli intensity (MMI) (Lew, 1990), 

and liquefaction occurrence (Benuska, 1990). 

LEAK-REPAIR STATISTICS FOR 

SAN FRANCISCO 

Leak repairs in San Francisco were predominantly minor. As listed in table l, nearly 90 percent of all repairs were 

on service lines. These lines, which are typically steel of less 

than 2-in. diameter, provide gas from the distribution main 

to the customer's meter. Many of the distribution mains are 

of cast iron with bell-and-spigot joints. This fact is also reflected in table 1, where 87 percent of the distribution-main 

repairs were made on cast-iron lines. 

The types of repairs carried out are listed in table 2, 

which points out several interesting characteristics. First, 

nearly 39 percent of the repairs to steel lines were minor, 

requiring only tightening of bolts or pipe caps. The next-greater 

number of repairs, which were assigned to a "miscellaneous" 

category, were temporary; most temporary repairs required 

additional work to make them permanent. Both of these categories, which together represent nearly 70 percent of the 

total repairs to steel lines, can be considered as minor repairs. Cast-iron repairs, which were largely (70 percent) concentrated at bell joints, are considered major. Overall, minor 

repairs (tightening and other categories) accounted for 71 

percent of all repairs. 

CORRELATION OF GRADE I REPAIRS 

WITH SURFICIAL DEPOSITS AND 

PEAK GROUND ACCELERATION 

A comparison of the locations of grade I leak repairs 

with surficial soil deposits and peak ground acceleration is 

shown in figure 1. Some correlation is evident between higher 

numbers of repairs and the sites of deep alluvial deposits. 

When the exact addresses of repairs are examined, a qualitative trend is evident for higher incidences of repairs near the 

boundaries between different soil deposits. However, this trend 

is not evident in figure 1 because of grouping of the data according to plat-map boundaries. 

As expected, no correlation is evident between the pattern of leak repairs and peak ground acceleration, possibly 

partly as a result of different concentrations of gaslines in the 

vicinity of seismic recording stations and the sparsity of seisSan Francisco 

0 USGS Recorded PGA, %g 

[Ã‘ CDMG Recorded PGA, %g 

- Loma Prieta Liquefaction 

1906 Liquefaction 

A Major damage to buildings 

A Minor damage to buildings 

Contour of greater than 6 

Grade 1 Leak Reports 

p3.7. 

0 

E ^* 

Figure 2.-Northern part of San Francisco, showing correlation of grade I leak repairs with areas of observed liquefaction and 

building damage. CDMG, California Division of Mines and Geology; MMI, modified Mercalli intensity; PGA, peak ground 

acceleration; USGS, U.S. Geological Survey. 
A132 PERFORMANCE OF THE BUILT ENVIRONMENT 

mograph stations. On the whole, the absence of correlation 

with peak ground acceleration is viewed as confirmation of 

the insensitivity of buried lifeline systems to ground shaking. 

REPAIR CONCENTRATION 

RELATIVE TO LIQUEFACTION AND 

BUILDING DAMAGE 

Most of the plat-map areas contain at least one occurrence of a leak repair, possibly as a result of the relatively 

large area used in mapping the city. An arbitrary selection of 

six leak repairs was used as a number distinguishing the limit 

between plat-map areas with high and low concentrations of 

repairs. These "high"-repair areas were mapped in figure 2 

with locations of observed building damage, liquefaction, and 

MMI boundaries. The boundary of high-repair areas is qualitatively drawn to encompass individual repair locations within 

the plat map. A correlation between liquefaction zones and 

number of leaks is immediately apparent. Building damage 

and MMI do not appear to be so well correlated with pipe 

repairs: Only 41 percent of the repairs fall into the MMI VII 

zone. From the data mapped in figure 2, the MMI VII contour could have been drawn to more closely reflect severe 

building damage in the sand-dune deposits north of Golden 

Gate Park. Then, 92 percent of the high-repair areas and 64 

percent of total repairs would have been contained within the 

MMI VII zone. 

An interesting conclusion from this comparison is that 

preliminary MMI designations are not particularly reliable. 

Little is gained from preliminary MMI estimates, and unless 

MMI contours are drawn on the basis of thorough reconnaissance, they should be treated cautiously. 

DISTRIBUTION-MAIN REPAIRS 

As mentioned above, most of the repairs addressed service lines. Because of the few repairs to gas-distribution mains, 

the correlations made are only tentative. The distribution-main 

repairs by PG&E are mapped in figure 3. The concentration 

of distribution-main repairs generally follows that for the total data base, with more repairs in the northeast quadrant of 

the city near Market Street. Nearly 50 percent of the distribution-main repairs are located north of Market Street and east 

of Leavenworth Street. Areas with distribution main repairs 

are mapped along with building damage, liquefaction, and 

MMI in figure 4. Distribution-main repairs correlate reasonably well with the sites of liquefaction during the 1906 San 

Francisco and 1989 Loma Prieta earthquakes. Except for this 

trend, the concentration of distribution-main repairs does not 

closely match that observed for service lines. 

isco 

Contour of 60m (200 ft) depth of 

unconsolidated deposits 

Distribution main repaits 

Bay mud 

Alluvium, >30m thick 

Alluvium, 0-30m thick 

Shallow bedrock 

Figure 3.-Northern part of San Francisco, showing correlation of grade I distribution-main repairs with areas of surface 

deposits. 
REPAIR PATTERNS FOR THE GAS-DISTRIBUTION SYSTEM IN SAN FRANCISCO A133 

SUMMARY 

The concentration of gas-distribution-system damage 

in poor soils observed in San Francisco is typical of those 

observed in past earthquakes. Heavier damage in the Marina 

District was not unexpected, given what is known of the site 

conditions there. At the time of the earthquake, the gas-distribution system in San Francisco had a considerable amount 

of cast-iron pipe with bell-and-spigot joints; this type of pipe 

has a history of poor earthquake performance. Media coverage focused on the Marina District, where structural damage 

was most severe and a major fire occurred. Actual damage to 

the gas-distribution system as a whole was light. 

ACKNOWLEDGMENTS 

I am grateful for the assistance provided by PG&E in 

obtaining details regarding their repair activities. Additional 

information on gasline performance was collected during 

postearthquake reconnaissance activities and specific investigations. Approval for the release of information by PG&E 

was a result of related investigative work being conducted 

for Steven P. Burke. The grade I leak-repair summary for 

San Francisco was provided by Leslie Stevens. I deeply appreciate the time taken by Steve Phillips and Sergio Bruni to 

provide tours of the Marina District and describe PG&E's 

response effort. Bob Moureau of PG&E's San Francisco Division provided plat maps for the key areas where repairs 

were made. An excellent summary of PG&E's overall response to the earthquake was presented by Phillips and Virostek (1990). 

REFERENCES CITED 

Benuska, Lee, ed., 1990, Loma Prieta earthquake reconnaissance 

report: Earthquake Spectra, v. 6, supp. 90-01,448 p. 

Lew, H.S., ed., 1990, Performance of structures during the Loma 

Prieta earthquake of October 17. 1989: National Institute of 

Standards and Technology Special Publication 778. 

Maley, R.P., Acosta, A.V., Ellio, F., Etheredge, E.C., Foote, L.J., 

Johnson, D.A., Porcella, R.L., Salsman, M., and Switzer, J.C., 

1989, U.S. Geological Survey strong-motion records from the 

Northern California (Loma Prieta) Earthquake of 17 October 

1989: U.S. Geological Survey Open-File Report 89-568,85 p. 

Phillips, S.H., and Virostek, J.K., 1990, Natural gas disaster planning and recovery; the Lorna Prieta earthquake: San Francisco, 

Pacific Gas & Electric Co. 

Shakal, A.F., Huang, M.J., Reichle, M.S., Ventura, C., Cao, T., 

Sherburne, R.W., Savage, M., Darragh, R.B., and Petersen, C., 

1989, CSMIP strong motion records from the Santa Cruz Mountains (Loma Prieta), California earthquake of 17 October 1989: 

California Division of Mines and Geology, Office of Strong 

Motion Studies Report OSMS 89-06, 196 p. 

MMI VII 

MMI VI 

San Francisco 

0 

- 

. . . . . . . 

A 

A 

Ei 

USGS Recorded PGA. %g 

COMG Recorded PGA, %g 

Loma Prieta Liquefaction 

190S Liqueiactinn 

Ma@ damage to buildings 

Minor damage to buildings 

Contour of greater than 

6 grade 1 leak reports 

Figure 4.-Northern part of San Francisco, showing correlation of grade I distribution-main repairs with areas of 

observed liquefaction and building damage. CDMG, California Division of Mines and Geology; MMI, modified Mercall! intensity; PGA, peak ground acceleration; USGS, U.S. Geological Survey. 

fi U.S. GOVERNMENT PRINTING OFFICE: 1999 - 773-051 / 20136 Region No. 8