EICA Report of
the Great East Japan
Earthquake Investigation(Flags at half-staff at Sen-En Sewage Treatment Plant)

April 2012

Great East Japan Earthquake Investigation Committee
The Society of Environmental Instrumentation,
Control and Automation (EICA)INDEX
Introduction
Chapter 1

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㌀ 1

Investigation Committee

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㌀ 2

(photograph only)
Chapter 2

Ishinomaki-Tobu STP ㌀
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㌀ 3
(photograph only)

Chapter 3

Sen-En STP

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㌀ 5

(photograph only)
Chapter 4

Minami Gamo STP

Chapter 5

Ken-nan STP

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㌀ 8

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㌀ 14

(photograph only)
Chapter 6

Conclusion

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㌀ 16

Chapter 7

Proposal

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㌀ 23

Afterword

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㌀ 25
STP : Sewage Treatment Plant

1

EICA Report of the Great East Japan Earthquake Investigation

Introduction
The Society of Environmental Instrumentation,
Control and Automation (EICA) is an association thatplant had reached the fatal condition of melting reactor
cores. The collapse of power company transmission

has conducted research on electrical and instrumentation of water supply and sewerage systems, waste
disposal treatment and prevention of air pollution. Itline towers and the damage of emergency generatorscaused AC power loss in STPs in the area that was hit
by the tsunami and lead to the grave situation of losing

had been established for 22 years as of 2012.
From the time of establishment, social conditions
involved in these research areas have changed

Lifesaving

dramatically. Social infrastructure of water supply
facilities, sewerage facilities, waste disposal treatment
facilities were still underdeveloped in many areas, andconstruction and operation of these had been rushed.
Also there were still many problems to face on the air
pollution prevention facilities, both from fixed emission
sources and mobile emission sources.
At that stage, it had to aim for the fulfillment of
power supply, process instrumentation control, network management and many areas that are related toelectrical and instrumentation systems in order tomeet the basic function of infrastructure. It was called
the era of construction.
Then, by using the maintenance of hardware
aspects such as construction facilities and the software
aspects such as the legal system and operation
management for each issue, with the cooperation andeffort of the government and academia, certain
progress was seen that came with the prospect ofsolving a fundamental challenge.
However, because of the Great East Japan Earthquake on March 11, 2011, Sewage Treatment Plant(STP) had been forced to conduct reviews.
STPs that were built near the coast have sufferedunprecedented damage by the tsunami and have been
entirely destroyed.
There are cross section forms of earthquake. Fromthe electrical and instrumentation point of view, there
are 3 characteristic points.
Damage caused by tsunami

Even though the damages because of the seismic
motion were small, the damages that were caused by
the external force of the tsunami, and sea water
infiltration were more significant. As a result,electrical and instrumentation facilities suffered se-

the pumping function.
Regardless of the tsunami, the staff of the STP, staff
of operation management company, and the construction officers were safely evacuated to the administration building at STP. Immediately after the earthquake, when there were information conflicts, despite
the loss of external power supply and equipment
damage, the result of daily disaster training, saving of
emergency power supply, the certainty of informationcollection and information transfer had been evaluated. But in one of the STPs, there was one womanfrom the management operation company who died in
the locker room. That means the issues of disastertraining and information transfer that should already
be resolved have still been neglected.
Some lessons were also learned in the recovery
phase.
Water soaked

Electrical and mechanical facilities were tremendously damaged. Being soaked by water for a time
has caused minor damage to building and civilengineering structures, but electrical and mechanicalfacilities were seriously damaged, especially facilities
that would breakdown when flooded even for a shortamount of time. It has required significant cost andtime to recover.
Power loss

Long term power loss has become a bottleneckproblem to recover activated sludge treatment
processes that requires much more amount of power,
and produces much more amount of sludge. Becauseof the large amount of power and treated sludge
needed, if the supplied power from power company is
not enough, even though the building and civilengineering structures, and electrical and mechanicalvere damage and required long term recovery.

facilities can be recovered, activated sludge treatment
processes still cannot be reopened. Because of thatproblem, the difficult situation has persisted.

Power Loss

Quick recovery

The power loss at Fukushima No. 1 nuclear power

In the areas that are far away from the coastline

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

and were not influenced by the tsunami, the water
purification facilities and sewage water pumping
stations were safe. After the power was restored,
early stage of water purification facilities and sewage
pumping stations had been achieved. In connection
with this, with the hard work of STP staff members,
broken equipment and sewer pipe lines had progressed partially. As a result, toilets and kitchens
became usable without any restriction.
Many reports related to Great

East

Japan

Earthquake have already been published, and thewhole picture is still being disclosed. Full scale
discussions about the reconstruction plans have begun.
However, there are very few report documents
related to electric and instrumentation system ofdevastated STPs. In response to this, EICA has
formed a research committee for the Great East Japan
Earthquake Investigation on July 2011. The research
objects are four large scale STPs that are located in
Miyagi prefecture which got tremendous damage
from the tsunami. Those STPsʼ electricity andinstrumentation recovery and reconstruction were
investigated by the committee on November with the

Chapter 1

2

cooperation of Sendai City and Miyagi Prefecture
Local Government.
On it, analysis of the damage from the impact of thetsunami was conducted, which includes identifying thesimilarity & differences between affected STP facilities.
We will propose the countermeasure of electricity
and instrumentation facilities of STPs across thecountry in the area that was affected by the damage ofGreat East Japan Earthquake and tsunami.
The content of this report provides Introduction,
research overview in Chapter 1 (photo only),
Facilities overview of Ishinomaki Tobu STP (25,300
m 3/d) in Chapter 2 (photo only), Sen.-En STP(222,000
m 3/d) in Chapter 3 (photo only), Minami Gamo STP(398,900 m 3/d) in Chapter 4, Kennan STP (125,000 m 3/d) in Chapter 5 (photo only), Conclusion in Chapter
6, Proposals in Chapter 7.
Using this report, we are trying to help thereinforcement of electrical and instrumentation systems of STPs that may be affected by tsunamis in thenear future.

Investigation Committee

1．Establishment of Committee
In the occurrence of the Great East Japan
Earthquake, in order to uphold the responsibility of theassociation, EICA Great East Japan Earthquake
Investigation Committee was established mainly by
the members of the association in July, 2011.

2．Member of Committee
Chairperson :Dr. Hiroaki Tanaka(EICA Chairman & Professor of Kyoto University)
Vice Chairperson :Takuji Nakazato (EICA Vice-chairman)
Kunio Waseda (EICA Vice-chairman)
Member :Manabu Katayama
Akio Sato
Shigeo Sato
Takeshi Sato
Takaaki Shinoda
Katsumi Shimamura
Yasuaki Tago
Kunio Tamura
Shire Toyoshisa
Masajiro Nakada
Hiromitu Moridera

Photo. 1. 1 Survey conducted at the emergency generator room in
Ken-nan STP (Photo taken in Nov. 2011)

Akihiro Yamada

3

EICA Report of the Great East Japan Earthquake Investigation

Chapter 2

Ishinomaki-Tobu STP (Photograph only)(25,300 m 3/d)

©2011 Terra Metrics, ©2011 Europe Technologies, SK M&C, Tele Atlas,
ZENRIN

Photo. 2. 1 Aerial photo of Ishinomaki Tobu STP

Photo. 2. 4 Upper part of the indoor biological reactor tank on the
2nd floor (Photo taken in Nov. 2011)
No significant damage to the building structure was found.

Photo. 2. 2 The moment when the tsunami hit (Photo taken bystaff member at the sewage treatment plant in Mar. 11,
2011)
Inundated up to GL (Ground Level) 6 m (above the 2nd floor levelof the 1 st sedimentation tank)

Photo. 2. 5 Equipment carry-in entrance on the 2nd floor (Phototaken in Nov. 2011)
The backfilled section of the equipment carry-in entrance wasdestroyed by Tsunami.

Photo. 2. 3 Interior of the administration building on the 1st floor(Photo taken by staff member at the STP in Mar.,2011)
The ceilings, etc. were inundated and destroyed.

Photo. 2. 6 Upper part of the outdoor biological reactor tank on the
2nd floor of the building (Photo taken by staff member
at the sewage treatment plant in Mar. 2011)

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

Photo. 2. 7 Local control panel of the sewage pump on the 1st floor(Photo taken by staff member at the STP in Mar.
2011)

4

Photo. 2. 8 The destroyed NTT (Nippon Telegraph andTelephone Corporation) service leading-in pole (Phototaken by staff member at the STP in Mar. 2011)
The power receiving wire pole was destroyed by the Tsunami.

Above : Immediately after the Tsunami. Submerged in water because it was installed on the basement floor. (Photo taken by staff member at the STP in Mar. 2011)
Below : Under restoration work after water was drained (Photo taken in Nov. 2011)

Photo. 2. 9 Grit chamber on the basement floor

Photo. 2. 10 Electrical room in the dehydrator building area
(Photo taken by staff member at the STP in Mar.
2011)
Inundated because it was installed on the 1st floor

Photo. 2. 11 Submerged sludge-treatment monitoring room on the
1st floor (Photo taken by staff member at the STP in
Mar. 2011)
Inundated up to ceiling level by the Tsunami

5

EICA Report of the Great East Japan Earthquake Investigation

Chapter 3

Sen-En STP (Photograph only)(222,000 m 3/d)

©2011 TerraMetrics Map data, ©2011 Europa Technologies, SK M&C, Tele
Atlas, ZENRIN

Photo. 3. 1 Aerial photo of Sen-En STP

Photo. 3. 4 Damaged blower equipment (Photo taken by staff
member at the STP in Mar. 2011)
Lifted and destroyed due to the buoyant force applied to the air
header pipe

Photo. 3. 2 Tsunami upon hitting the area (Photo taken by staff
member at the STP in Mar. 11 2011)
The tsunami height was GL 1.3 m on the water-treatment side andGL 2.8 m on the sludge-treatment side.

Photo. 3. 5 Temporary storage yard for the disassembled digestion tank (Photo taken in Nov. 2011)
The tank, which was destroyed by Tsunami, was disassembled andplaced temporarily in this yard.

Photo. 3. 3 Toppled digestion gas tank (Photo taken by staff
member at the STP in Mar. 2011)
The gas tank was toppled due to the buoyant force of the sea water.

Photo. 3. 6 The water treatment facilities (Photo taken in Nov.
2011)
The section covered with the blue sheet is the temporary storageyard for the sludge of tsunami.

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

6

Photo. 3. 7 The temporary dehydrator (Photo taken in Nov. 2011)
Sludge brought about by the tsunami is treated using the temporary
dehydrator.

Photo. 3. 10 Tsunami trace in the electrical room on the 1st floor of
the sludge treatment building (Photo taken in Nov.
2011)
The water level can be estimated by the flood trace.

Photo. 3. 8 Caved-in road within the facilities because of groundliquefaction (Photo taken in Nov. 2011)

Photo. 3. 11 Simple aeration (Photo taken in Nov. 2011)
Simple aeration, that means aeration without return sludge, wasperformed temporarily

Photo. 3. 9 Tsunami trace on the electrical room entrance on the
1st floor of the sludge treatment building (Photo taken
in Nov. 2011)
The water level can be estimated by the flood trace.

Photo. 3. 12 The disinfection tank (Photo taken in Nov. 2011)
Disinfection was performed strictly for sanitation.

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EICA Report of the Great East Japan Earthquake Investigation

Photo. 3. 13 Centrifugal dehydrator installed on the high frame(Photo taken in Nov. 2011)
Not inundated because installed at elevation, but auxiliary equipments were broken

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

Chapter 4

Minami Gamo STP (398,900 m 3/d)

1．Facility overview of Minami Gamo STP
1. 1

8Location

2．Overview of Electrical Facilities
2. 1

High voltage power receiving facility

Minami Gamo STP is located at the right side bankof the estuarine of Nanakitada River in Sendai city.

66 kV/50 Hz/1
line/aerial cable/Gas Isolated System

The plant is facing the Pacific Ocean and Teizan canalcuts across the plant field. (Photo. 4. 1)

2. 2

Substation facilities (Main transformer)

10,000 kVA/66 kV/6.6 kV/1
Unit of Oil-immersed type7,500 kVA/66 kV/6.6 kV/1
Unit of Oil-immersed type
2. 3

Power distribution facility (6.6 kV power distribution panel, low voltage power distribution
panel, transformer panel)

Extra high voltage electrical room, water treatment
facilities electrical room, sludge treatment facilities
electrical room
Approximately 180 panels
2. 4
Photo. 4. 1 Aerial photo of Minami Gamo STP Tsunami came fromsoutheast direction.

3,500 kVA/66 kV/50 Hz/2
Units of diesel engine
2. 5

Topographically, the Plant is located in the lowland
area. Therefore the sewage flows by gravity to STP,
and to the Pacific Ocean.
1. 2Control center board, relay panel, junction terminal
panel, operation panel in the field
Approximately 600 panels
3．Overview of Instrumentation Facilities
3. 1

Monitoring and Controlling Facilities(1) Water treatment system

Population of the treatment area

716,192 people
1. 4

Control operating facility

Public sewerage area

Minami Gamo treatment area (Approximately 60%
of treatment area in Sendai City.)
1. 3Emergency generators

Treatment method

Standard activated sludge method (anaerobicaerobic method) and chlorination.

3 CRT monitoring equipment units, graphical panel
monitoring equipment, 1 server unit (dual system), 8
controller units,(2)Sludge treatment and incineration system

Maximum treating amount : 398,900 m /d

5 CRT monitoring equipment units, graphical panel
monitoring equipment, 2 server units (dual system),

1. 6

12 controller units,

1. 5Treatment capacity
3

Installation timeline1964 : Basic treatment facility by sedimentation
method started to operate.
1979 : Complete treatment facility started to operate
1. 7

Major Facilities Construction Company(under construction)

Settling basin : Hitachi Kiden Kogyo, Ltd.

3. 2

Instrumentation

Approximately 210 units
4．Damage and restoration of the electrical facilities
4. 1

Damage situation

Primary and final sedimentation tank : Hitachi Plant
Construction and Services Co., Ltd.
Aeration facility : Sanki Kogyo Co., Ltd.

The Great East Japan Earthquake that occurred at
14 : 46 on March 11, 2011 had stopped the powertransmission system from Tohoku Power Company.

Sludge treatment prosess : Tsukishima Kikai Co., Ltd.

Then, an attempt to start two emergency generators
was automatically made. Although one of the 2 units
had broken down due to the cooling pipe damage, theIncineration facility : Kubota Co., Ltd.
Electric/Instrumentation : Hitachi Co., Ltd.

9

EICA Report of the Great East Japan Earthquake Investigation

other unit was started and electricity was generated.
It had supplied electricity until the system was flooded
by the Tsunami.
The damage due to the earthquake was rather
small, but the Tsunami that came in 30-40 minutes
after the earthquake damaged most of the electricaland mechanical facilities on the 1 st floor and thebasement. Then the function of STP was stopped.
(Photo. 4. 2)

Photo. 4. 3 Electrical towers. (Photograph taken in April 2011)
The electrical tower withstood the Tsunami attack. It did notcollapse and was not damaged.

of the STP were largely damaged by the Tsunami.
The wall of the main pump building was bent, and the

Photo. 4. 2 Tsunami attack (Photograph taken in Mar 2011)(Provided by Sendai city)walls of the air blower building were destroyed andcracked open by the impact of the Tsunami. The
distribution panels and operator control panels placedin the building were mostly flooded and lost theirfunction due to the impact. (Photo. 4. 4, Photo. 4. 5)

The tsunami wave reached 10.5 m from groundlevel (G. L), (Tokyo bay Point average level (TP)+12.85 m) at its peak near the closest area to thecoast, and G. L. 4 m (TP+6.9 m) around the area justacross the Teizan canal. (Fig. 4. 1)

Photo. 4. 4 Wall of the main pump building. Tsunami came andstruck the building from the right side in the photo andbent the wallFig. 4. 1 Flood level (Provided by the STP)

The electrical towers on the STP side were safe
from the earthquake and tsunami. However the
primary transmission line had lost power because
several transmission towers outside of the STP had
collapsed. Due to this, high voltage power could not be
used until December 2011, so the other high voltage
service was used as emergency power supply.
Prolonged restoration of the transmission line of
Tohoku Power Company had serious effects on therecovery of the STP. (Photo. 4. 3)
The water treatment plants built on the ocean side

Photo. 4. 5 Inner part of the air blower building. Air blower andelectric motors were covered with the rubble thatentered from the destroyed wall

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

10

Meanwhile, the equipment installed outside, on the
1 st floor, and on the basement in the administrationbuilding and the sludge treatment and incineration
facility located on the west side of the Teizan canalwere flooded, but the water level was rather low. The
equipment on the 2 nd or higher floors were lessdamaged.
Main mechanical facilities such as dehydrators
installed on the 2 nd or higher floors were not directly
damaged, but operation of some equipment weresuspended due to the submergence of auxiliarymachines on the 1 st floor. The wall of the housing forthe high voltage power was largely damaged bycollision of drift wood, this may be because ofstructural weakness, the distribution panels inside hadcollapsed due to the impact and submerged and broke
down. (Photo. 4. 6)

Photo. 4. 7 Housing of the emergency generator facility (Photograph taken in Apr.2011)
Major damage could not be seen on this building.

(1) Right after the disasterMaximizing the usage of gravity flow, influent →primary sedimentation tank → bypass gate → effluent,
the basic process and effluent had been carried out
without electric power.
(2) Temporary power generator

A temporary dehydrator was installed in the middleof April 2011. According to the plan, power was
supplied temporarily with a portable type of diesel
engine generator.
(3) Backup receiving power unit

Photo. 4. 6 Housing for the high voltage power
Largely damaged wall because of drift wood.

It started to receive electrical power (6.6 kV/1.998
kW/1 line) from Tohoku Power Company as backup
power supply from the middle of May 2011. In
accordance with the restoration of the mechanicalfacilities such as automatic settling basins, sedimentation tanks, sludge pumps, and centrifugal dehydrators,

The cable duct and cooling pipe of the emergency
generator were partially damaged by the earthquake,but there was no damage and no flood in the building.

the power had been fed sequentially and sludge
treatment was reopened. (Photo. 4. 8)This is because the tsunami height was low in thisarea, the structure of the building was firm, secured
with the sound insulation and elimination of vibration,

Tohoku Electric Power is planning to recover the(4) High Voltage power receiving facility

and the housing adopted an airtight structured door
and no windows. (Photo. 4. 7)
The Direct Current (DC) power unit was notdirectly damaged by the earthquake nor the tsunami.
However, the long term blackout caused overdischarge of the storage battery.
4. 2

Recovery situation of the electrical facilities

Based on the Business Continuity Plan (BCP) for
Minami Gamo STP, recovery of the temporary
electrical facilities were conducted along with securing the effluent flow channel and sedimentation
facility, and recovering the sludge treatment facility.

Photo. 4. 8 Temporary receiving power unit 6.6 kV installed on
the primary sedimentation tank. (Photograph taken in
May 2011)

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EICA Report of the Great East Japan Earthquake Investigation
Table 4. 1 Recovery situation of damaged electric/instrumentation at Minami Gamo STP(By EICA analysis of sewage treatment plant questionnaire)water
treatment

sludgetreatment

Damage byearthquake

Damage by
the Tsunami

Extent ofdamagePower receiving equipment

None

Damaged116 panels

TemporaryMay 2011

Power transforming equipment

None

Damaged20 panels

May 2011

Power distributing equipment
Central supervision facilities

None
None

DamagedDamaged152 panels
53 units

Field operating board

None

Damaged290 panels

May 2011

Mar 2015

Field instrumentation(Number of sensors and panels)

None

Damaged

151 units

May 2011

Mar 2015

May 2011

Jun 2012
Jun 2012

Permanent
Mar 2015
Mar 2015
Mar 2015
Mar 2015

Power receiving equipment

None

Damaged30 panels

Power transforming equipment

None

Damaged6 panels

Power distributing equipment

None

Damaged24 panels

Jun 2012

Central monitoring room
Field operating board
Field instrumentation(Number of sensors and panels)

DamagedDamagedDamagedDamaged19 units
150 panels

May 2011

Jun 2012
Jun 2012

None

Damaged60 units

May 2011

Jun 2012

Power receiving equipment

None

Damaged12 panels

Jun 2012

Power transforming equipment
Power distributing equipment

None
None

DamagedNone

2 panels
None

Jun 2012

None
DamagedDamagedNone

6 units
2 units

Mar 2015
Jun 2012

None
None

None
Damaged

2 units
2 panels

None

Damaged

2 units

None

None

None

None

None

None

None

None

None

Central monitoring room
Emergency generator
Commonfacilities

Estimated recovery time

Item

DC power supply
Field operating panel
Field instrumentation(number of sensor and board)
Inside transmission and communicationequipment
Outside transmission and communicationequipment
OthersMay 2011

Jun 2012
Jun 2012
Jun 2012

Note) Facilities are classified as below.
Power receiving equipment : High and low voltage panel, DC panel, UPS
Transforming equipment : Transformer, transformer panel
Distributing equipment : Motor control center panel, relay panel, junction terminal panel
Central monitoring room : Instrumentation panel, monitor and control equipment, ITV system
Field operating panel : Operating panel in field
Field instrumentation : Measurement instrumentation, transmitter

power supply in June 2012 as originally scheduled.
New electrical substation has been ordered and underconstruction.
4. 3

and small-scale hydropower generator will be promoted to establish an STP that is less vulnerable totsunami disaster.

Policy for restoration of electric facility

Minami Gamo STP can do primary treatment andeffluent by gravity flow without using pumps becauseof the geographical condition. This condition also
avoids limitation of using sewage and overflow in thecity. By exploiting this advantage, the recovery plan
will be continued while maintaining this primary
treatment that can be used in case of emergency.
According to this policy, primary sedimentation tanks
will be reconstructed in their former level, biologicalreactor (aeration tank) and final sedimentation tanks
will be reconstructed on the 2nd floor in order to avoid
tsunami disaster, Main electrical facilities will be
installed on the 2 nd or higher floor. For securing thepower during emergency situations, solar cell facility

5．Damage and recovery of the monitoring control
equipment
5. 1

Damage situation of the instrumentation

Main devices of monitoring control equipments suchas CRT monitoring device and servers werenʼtdamaged because they were installed in the central
monitoring room on the 2 nd or higher floors. However
8 controller units for the water treatment system and2 controller units for the sludge treatment had broken
down because of the flood.
The instrumentation such as sensors and transmission equipment panel, instrumentation switch panels
that were installed outside on the 1 st and basement had
all broken down due to the flood.

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

5. 2

Recovery situation of the monitoring control
equipment(1) Monitoring control equipment

For emergency recovery of existing centrifugal
dehydrator, 2 controller units were installed temporarily, and additionally the undamaged auxiliary relay
panels and control panels were used. This enabled theoperation of the facility. (Photo. 4. 9)

5. 3

12

Recovery policy of monitoring controlling equipment

For countermeasure to prevent the monitoring
control system from shutting down, the CRT monitoring control equipment and controller will be installedon the 2 nd or higher floors to minimize the flood
damage in case of a Tsunami.
6．Task of restoration
The biggest feature point of Minami Gamo STP isthat basic sedimentation treatment and effluent can be
carried out without using power if the bypass routefrom primary sedimentation tank to the emergency
effluent gate is used.
On March 12, 2011, the following day of the disaster,

Photo. 4. 9 Temporary sludge treatment controller (Photographtaken in May 2011)
It is installed in the electric room on the 4 th floor of sludge treatmentbuilding.

However, during the investigation period (Nov.
2011), almost all water treatment and sludge treatment were suspended because the electricity andmechanical facilities in the sewage treatment plant
werenʼt recovered yet.

the old effluent channel gate (normally closed) was
opened manually and malfunctioned emergency effluent gate was destroyed on March 17, 2011 to secure
the effluent function.
On March 18, 2011, rubble in the STP was removed
and water in the primary sedimentation tank was
drained. Solid chlorination disinfection had begun
right after (Photo. 4. 11) and about one month later, on
April 14, 2011, injection of sodium hypochlorite had
begun. (Photo. 4. 12) After that, sewage could be(2) Instrumentation equipment

Since the sewage flows by gravity without pumping
and also water level gauge of pump well and pressuregauge for control were unnecessary, inflow meter formonitoring (ultrasonic wave pulse Doppler method)
was preferentially recovered temporarily. (Photo. 4.
10)Photo. 4. 11 Disinfection with solid chlorine

Photo. 4. 10 Temporary inflow meter (Photograph taken in April
2011)
It is installed temporarily at the inlet of the STP.

Photo. 4. 12 Injection of hypochlorous acid in temporary facility

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EICA Report of the Great East Japan Earthquake Investigation

Table 4. 2 Comparative review of sewage treatment methods between primary treatment and complete treatment restoration for Minami
Gamo STP
Treatment
methodCapability withexisting facility

catalytic oxidation

Rapid filtration+
Feeding coagulant

Standard activated sludge,
membrane separation activatedsludge, carrier, batch typeactivated sludge

Modified aeration○
Use pre-aeration tank○
Use pre-aeration tank×
Unable to secure necessary
capacity of tank×
Unable to secure necessary
capacity of tank

―

―

―

―

Securing BOD○○
less than 60 mg/L BOD approximately 40 mg/L○△
Maintenance costLess chemical costMore chemical costLess sludge generation
More sludge generation

Fig. 4. 2 Influence on the effluent water by the earthquake
disaster (x axis is month, y axis is mg/l)

treated by primary treatment. Sodium hypochlorite
for disinfection was injected and effluent discharge to
the Pacific Ocean had been done.
The effluent water quality during this treatment isshown in the Fig. 4. 2. The level of COD and SS
largely went down right after the disaster, but
improvement of SS was seen after the primary
treatment had begun. Furthermore, water quality
deterioration at the environmental standard place was
not observed. The major reason being considered forthis is the diluting effect by effluent to the Pacific
Ocean.
Restoration of the treatment facility is anticipated tobe completed in 5 years. Therefore the sewage
treatment method should be shifted from primary
treatment to biological treatment and disinfection in
3-6 months. Usage of “Catalytic oxidation method”
has been promoted after a comparative review of thetreatment methods as in the Table 4. 2.
The sludge treatment resumed sludge extraction
from the primary sedimentation tank and also sludge
treatment in the temporary dehydrator housing.
(Photo. 4. 13) After the introduction of the backup
high voltage substation facility in middle of May 2011,

Photo. 4. 13 Temporary dehydrator housing. (Photograph taken
in May 2011)
Temporary tent house was set up and equipment was installedinside.

treatment of generated sludge resumed with existing
centrifugal dehydrators through the temporary sludgepump.
Dehydrated sludge could not be incinerated becauseof power shortage ; therefore the sludge was conveyed
by truck to land-fill site and partly conveyed out andtreated in Miyagi Prefecture.

References :1)

Sendai city sewerage work damage resulting from the Great
East Japan Earthquake and recovery situation. Sendai city,(Sep. 2011)
2 ) Sendai city STP damage resulting from the Great East Japan
Earthquake.
Sendai city Construction Bureau
3 ) Report for recovery policy of Sendai city Minami Gamo STP
Sendai city Minami Gamo STP recovery policy committee,(Sep. 2011)
4 ) Sewerage recovery strategy for continuance of STP utilization
and retention of hygienic environment ― effective utilizationof [Sendai city Sewerage network]―
Sendai city Construction Bureau, (Apr. 2011)

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

Chapter 5

14

Ken-nan STP (Photograph only)(125,000 m 3/d)

Photo. 5. 1 Aerial photo of Ken-nan STP

Photo. 5. 4 Restoration status of destroyed upper part of water
treatment facilities (Photo taken in Dec. 2011)
Treatment by standard activated sludge process was partiallyrestarted

Photo. 5. 2 The destroyed upper part of the water treatment
facilities (Photo taken in Apr. 2011)
The facilities was directly hit by the Tsunami

Photo. 5. 5 Restoration status of local electrical room (Photo taken
in Dec. 2011)
Restoration of the sand-filtration system

Photo. 5. 3 Damaged electrical room (Photo taken in Apr. 2011)
Electrical equipment was inundated or destroyed by the Tsunami

Photo. 5. 6 The destroyed pH meters for Aeration Tank
and 2 (Photo taken in Apr. 2011)
Mounting pole destroyed by the Tsunami©2012 Cnes/Spot Image, DigtalGlobe, GeoEye Map data, ©2012 ZENRIN

No. 1

15

EICA Report of the Great East Japan Earthquake Investigation

Photo. 5. 7 Restoration status of supplied-sludge density meter for
No. 3 dehydrator (Photo taken in Oct. 2011)
The equipment in the No. 1 dehydrator building was the first to berestored.

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

Chapter 6

Conclusion

1．Damage Characteristics
Damage conditions at each STP are summarized inTable 6. 1. There were various forms of disaster fromthe earthquake. In general, the earthquake itself
caused little destruction or damage, but the destruction from the impact of tsunami as well as flood
damage it caused has been immense. Conversely, inbuildings where water-proofing and anti-inundation
measures such as water-tight doors/gates were inplace, a certain level of efficacy has been noted.
Common forms of damages at each sewage treatment plant are as follows :1. 1 Power distribution Feeds/Connection Points fromPower Companies

All of the STPs had slight earthquake damage ;however, there were some cases where incoming
service poles, leading from the power company to theplant, were knocked down by the tsunami. There
were no collapsed incoming transmission towers or
switch towers at Minami Gamo STP, but there werecollapsed distribution transmission towers fromTohoku Electric Company, which led to serious power
outages. Hence, recovery is taking a long time.
However, at Sen-En STP, the distribution transmission
towers and incoming service poles were not knocked
down and power transmission from Tohoku ElectricCompany was restored within two weeks which leadto the STPʼs speedy recovery.
1. 2

16

Substation Facilities

to cooling-water pipes, there were some burns tomachineries. However, 1 in 2 machines started up
normally and succeeded in producing power. On theother hand, other STPs were not damaged by theearthquake, but since power generation facilities werelocated on the first floor, the facilities sustained someflood damage. Even when flood damage was avoided,
auxiliary systems needed to run the facilities, such asfuel transfer pumps, etc., were flooded and these units
lapsed into non-power generation mode.
1. 4

Water Treatment Facilities

Though cases of power line sections being cut by
earthquake-caused ground subsidence have been
observed, there were no damage reports of toppled
electrical panels. Panels that were set up on the 1st
floor level or basement − where they sustained a lotof tsunami flood damage − were catastrophicallydamaged.
1. 5

Sludge Treatment Facilities

There was no substantial damage or collapse panel
due to the earthquake. However, panels at each STP
that were installed on the 1st floor or basement −where they sustained a lot of tsunami flood damage −were catastrophically damaged. In many cases,
sludge dehydrators installed on the 2nd floor were notaffected by the flood. However, since auxiliary
systems needed for the facilities to run were installedon the 1st floor, or basement, these systems were
flooded and disabled.

Damages from the earthquake were minor except
for damages to some open-structure type disconnec-

1. 6 DC Power Supply Systems/Uninterruptible Power

tors at Sen-En STP. Conversely, local electrical rooms
situated on the 1st floor of each STP were destroyedby the impact of the tsunami. Tohoku Electric

There was no damage due to panel collapse ;however there were many cases where prolonged

Company restored power at Ken-nan STP by the endof March 2011. The speedy recovery can be linked to
immediate resumption of supply needed to power the
2nd floor local electric rooms, which were notinundated by the tsunami. On the other hand, there
was no flood damage to the 2nd floor local electricrooms at Ishinomaki Tobu STP, but its recovery wasdelayed because Tohoku Electric Company was notable restore power until June 2011.
1. 3

Emergency Generator

There was damage to wiring ducts at Minami Gamo
STP caused by the earthquake. Also, due to damages

Supply (UPS)

power outages led to excessive discharging of leadstorage batteries resulting to complete damage withno hope of recovery. In addition, there were power
supply units in several of the electrical rooms on the
1st floor of Sen-En STP that escaped flood damage
because of being situated in highly watertightelectrical rooms.
1. 7

Instrumentation

There were instruments that were destroyed by the
impact of the tsunami or by flooding/insulation failure.
Instruments set up inside buildings and in piping
galleries did not appear to be damaged, but could not
be used because of insulation failure caused by the

17

EICA Report of the Great East Japan Earthquake Investigation

flood.
1. 8

Central Monitoring Equipment

Though there were some STPs where Liquid
Crystal Display (LCD) monitors fell over due to theearthquake, there was no damage from panels
collapsing, etc. Also, since the central monitoring
room for each STP was set up on the 2nd floor or
higher floors, there was no damage from flooding.
However, the sludge treatment monitoring and control
rooms at Ken-nan STP, and at Ishinomaki Tobu STP,
were on the 1st floor and were thus flooded by thetsunami. In addition, control panels that were set upon the 1st floor of these buildings were damaged byflooding and the impact of the tsunami and said
equipment was unable to perform monitoring andcontrol operations.
1. 9 Equipment Operation and Operation Control Panels

Panels, such as motor control centers, auxiliary
relay panels, on-site control panels, control panels, etc.,that were set up outdoors, on the 1st floor, or basement
were affected by the flood damage/insulation failure
or impact from the tsunami. Even if the panel itself
avoided being flooded, instances of insulation failure
due to flooding at connection points, such as junction
boxes, etc. were observed.
1. 10

Off-site Pump Stations(Remote Monitoring Equipment)

There was no damage due to collapsing panels, but
NTT telephone service poles collapsed at each STP
due to the tsunami and dedicated network lines
between pump stations were cut, thus making theminoperative.
1. 11

Communication Equipment(Disaster Management Radio Communications)

There were STPs where disaster management
radio communications functioned normally and STPs
where breakdowns at the disaster management
authority led to disconnections in mid-operation. Since
this was the designated means of communication tosecure correspondence on which lives depended,
where normal functionality was not present, earthquake information and tsunami information was
obtained by means of digital TV of cellular phones, email, etc. on public communication networks.
1. 12

Other Information

Directly following the earthquake, those staff
members associated with sewage facilities acted
calmly and appropriately, basing their actions on the
Disaster Management Manuals or the BusinessContinuity Plans (BCP) enacted at each STP. It isthought that this was a result of precise information
gathering/transmission due to regular disaster training. Meanwhile, when power was restored toemergency generators, there were cases where
standardized visual checks of local electric rooms andtransformer facilities − which were located a long
distance away from administrative buildings − were
performed. Learning from this experience, it isconcluded that in situations where leaving theadministrative buildings is extremely dangerous, as
was the case with this tsunami, a review of power
distribution plans and of the process manual for the
restoration of electrical equipment is needed.
2．Challenges
As for the damages, it has been recognized that thedistinct feature of this disaster is that there was far
more damage, such as flooding and collapsing ofelectrical and instrumentation facilities, caused by thetsunami than the earthquake. Thus, not only areearthquake-proof countermeasures necessary forelectrical and instrumentation facilities, but it is also
important for earthquake and tsunami countermeasures that involves building a highly reliable systemthat includes external factors such as the loss of
distribution power lines. Challenges for earthquakeproof and tsunami-proof countermeasures are as
follows :2. 1 Reconsideration of Equipment Locations, Installation
Methods, Wiring and Plumbing

Besides earthquake-proof countermeasures forbreaking cables and collapsing electric panels, in orderto prevent flood and tsunami impact damage, important measures include : Installing equipment where it
will not be hit directly by a tsunami, installingcountermeasures to prevent indoor flooding, or in theunlikely event that there is flooding, installingcountermeasures so that the damage is decreased tominimum.
2. 2 Reducing External Power Source Dependency
Rates & Fallback Procedures When Power is Lost

The treatment methods and operational equipment
for each STP in the recovery stage are summarized inTable 6. 2. Simply, whether it is full recovery or
temporary repairs, the geographic location and theinstallation emplacement of each STP varies so thatthe required equipment and treatment method foreach recovery stage (step-by-step) also differs. TheseGreat East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

are also the factors that decide the amount of power
required for recovery or temporary repairs. Thus, itis necessary to conduct a thorough preliminary
investigation in order to address thoughts like, “even if
it is broken, how can functions recover quickly,” or“even if it is broken, partial functionality will bemaintained and fallback procedures will come into
effect,” and to see how much power will be used for

3. 1

18

Power distribution Feeds/Incoming Connection
PointsIn order to prevent toppling of transmission towers
or service poles from tsunami impact, it is desirable tohave power lines from the power company buried
underground.
3. 2

Substations(Grid Connection)

recovery and emergency procedures as well as which
disinfection treatments to perform.

Figure 6. 1 shows backup power distribution foressential services and grid connection of renewable

In the case of power loss due to collapsed
distribution power lines, it is important to study the
implementation of independent sources of energy,

energy.
Since ensuring power is difficult during a disaster, it
is recommended that we reduce dependence onsuch as renewable energy and storage batteries, inorder to independently supply the minimal power
needed for emergency procedures like sewage pump-external power sources through the introduction ofrenewable energy. Specifically, connecting renewableenergy sources like solar cell power to the pumping

ing, sedimentation and simplified disinfection.

motor and using large scale storage batteries for gridindependent operation in an emergency are useful.
Even in such cases, earthquake and tsunami impact/flooding countermeasures are needed. Sufficientresearch must be put into the location of facilities andplumbing/wiring.

2. 3 Increasing System Reliability as a Whole & Fallback
Procedures/Reducing Operation failure period

Due to external factors associated with tsunami
flood damage, it is necessary to look at things from theviewpoint of maintaining the reliability of electricalequipment as a whole ; even if certain equipment inlocal electrical rooms is damaged, back-up power canbe sent from other local electrical rooms. And, even if
some damage is sustained, in locations that are far
removed from the damaged area, it is important tobuild system configurations where fallback proceduresare possible, thus making sure that the entire system
is not affected
2. 4

Information Sharing, Plans for Cooperation Between Municipalities(Power Distribution Equipment)

For this disaster, the complete loss of power frommajor electrical equipment needed for facility operations, due to electrical breakdowns and damage causedby flooding and tsunami impact, was a distinguishing
characteristic. Thus, as far as loads needed forrecovery and minimum loads on electrical equipment
needed for initial treatment are concerned, even whenpower supplies to major electrical equipment are lost,
if power can be supplied by connecting to alternate

For speedy recovery and backup to occur between
municipalities during a disaster, there must be quick
and accurate information collection, even when there
is confusion directly following an earthquake. The
necessary information concerning disaster conditions,emergency measures, emergency repairs, temporary
equipment procurement plans, etc. need to becollected quickly and smoothly, by means of various
forms of communication that are resistant to disasters.
There is also a need to construct plans for information
sharing.
3．Countermeasures
The earthquake and tsunami countermeasures forelectrical and instrumentation equipment, which wetouched upon above, will be described below.

Fig. 6. 1 Conceptual Diagram of Renewable Energy and Power
Grid Connection

19

EICA Report of the Great East Japan Earthquake Investigation

substations and district electrical rooms, then theseflexible power distribution routes become viable.
3. 3

Emergency Generator

Inspecting the deployment of flooding countermeasures for emergency generator, including auxiliaries, isimportant. It is desirable to have all equipment,
including auxiliaries, on the 2nd floor or above. We
must also pay attention to wiring/piping between fueltanks and fuel pumps in particular. When installing
equipment on the first floor is unavoidable, it isimportant to use flood-proof doors as a method for
mitigating flood damage.
Also, there is a need to ensure that the estimatedcapacity of fuel tanks for emergency generator issufficient for long-term power stoppages. Ensuring
the required fuel capacity for running 24-48 hours, assuggested by the Japan Ministry of Land, Infrastructure, Transport and Tourismʼs Sewage Works
Earthquake/Tsunami Countermeasures Technical
Investigation Committee, is a given, but if transportation corridors are cut off, we can assume that there
will be difficulties associated with ensuring that
additional fuel will arrive. Hence, running in conjunction with independent power sources becomes viable.
In addition, “dual-fuel” emergency generator that canswitch between liquid fuel and gas fuel is feasible.
3. 4

Water Treatment Facilities

Preventing flood damage from a tsunami is criticaland it is important to install control panels on upper
floors or to install flood-proof doors as a method for
mitigating damage. In addition, using a submersible
pump for the main pump and taking water-proofing
precautions for power sources and control cableterminal is important. When installation in theunderground is unavoidable, steps must be taken
based on the assumption that equipment will be
submerged.
3. 5

Sludge Treatment Facilities

and it is important to install Power Supply Systems on
upper floors or to install flood-proof doors as a method
for mitigating damage. Also, when alternating current
power supplies fail, including emergency generators,
in order to stop the discharging of electricity fromstorage batteries before they become depleted anddamaged, it is important to shut down batteries
automatically through the use of an over-discharge
alarm.
3. 7

Instrumentation Facilities

During this disaster, instrumentation facilities
installed outside were destroyed or flooded by thetsunami and thus became useless. However, there
were some equipment, which were installed insidebuildings or piping galleries, that remained unharmed.
Thus, countermeasure precedents, such as using
water-proof/flood-proof converters or installing converters on the 2nd floor or above, should beconsidered. Moreover, sampling of instrumentationequipment needed at the recovery stage and back-up
equipment procurement are also important.
3. 8

Central Monitoring and Control Equipment

During this disaster, central monitoring and control
equipment installed on the 2nd floor did not get
severely damaged but the controllers installed in local
electric rooms on the 1st floor received flood damage.
If a local electric room gets damaged, the central
monitoring and control equipment will not be able tofulfill its role. So, it is thought that there is a need to
put these rooms in locations that are safe from disasteror to examine regional electric room back-ups,
decentralization, etc. Methods for installing controllers on upper floors, or for making the primaryequipmentʼs controls redundant between different
controllers, are to be considered.
3. 9

Equipment Operation Panels

To prevent flood damage caused by a tsunami plans
to mitigate damage through the installation of

To prevent flood damage caused by a tsunami,
installing sludge dehydrators, including auxiliaries, on
the 2nd floor or above is desirable ; however, whenequipment operation panels on second floors or
through the installation of flood-proof doors areimportant. Also, water-proofing countermeasures for

installed on the 1st floor, methods to mitigate flood
damage, such as flood-proof doors, are important.
When installation in the underground is unavoidable,

power sources/control cable terminal is critical.
Since there are a lot of cases of on-site control panels
being installed outdoors or on lower floors, there is a

steps must be taken based on the assumption that
equipment will be submerged.

need for drastic countermeasures. As an alternative
to conventional on-site control panels, replacement byclose-range wireless equipment, for example Tablets

3. 6 DC Power Supply Systems/Uninterruptible Power
Supply (UPS)

Preventing flood damage from a tsunami is criticalor Exclusive PHS (Personal Handy-phone System) is
effective.

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

3. 10 Off-site Pump Station Remote Monitoring Equipment

Poles of NTT collapsed and dedicated network lines
were cut by the tsunami, thus rendering monitoring
equipment inoperative. So, it is necessary to install
network lines underground in order to avoid this in the
future.
Also, in cases where a facility is damaged temporarily by a disaster, it becomes important to have
independent operational control of off-site pumpstations based on the assumption of network troubles.
It is also important to make networks highly reliable.
Remote monitoring is effective only when network
communications can be established without any
problems, so establishing a stable network between
the disaster control center, the STP, and off-site pumpstations using the most reliable private network lines− fiber optic cables installed in the sewage pipes − isrecommended.
Also, automatic operation of manhole pump stations
is possible when there is network trouble. In order tocontinue remote monitoring at off-site pump stations
from the STP, it is valid to use communication line
back-up plans that incorporate both commercial
dedicated lines and private lines, such as analog 3.4kHz
dedicated lines/private lines or digital dedicatedlines/private lines.
3. 11

20

This can be achieved through satellite phones or
through connecting STPs and disaster control centerswith private lines by utilizing a dedicated communication network with fiber-optic cables laid in sewage
pipe-line grids. Also, within STPs themselves, it isrecommended to prepare private communicationequipment such as PHS.
3. 12

Disaster Information Ascertainment System

Amid the chaos directly following this disaster, we
propose a Disaster Information Ascertainment
System that aims to collect information quickly andaccurately. In order to grasp disaster conditions
quickly and accurately, everyone sends critical datalike safety status, power status, main pump conditions,off-site pump station conditions, etc. to a Cloud Data
Center where it can be assembled into a database. We
also suggest having a standardized format forreporting emergency operations, emergency repairs,
and procurement plans for temporary equipment, etc.
which covers conditions of major facilities andconditions of major equipment during each recovery
stage. Last but not least, we propose constructing aplan to communicate quickly and reliably with thedisaster control center by utilizing disaster proof
platforms such as satellite phones and sewage pipe
fiber-optic networks.

Emergency Communication Facilities

In this disaster, there were cases where, due todamaged public emergency radio stations, the designated means of communication for securing thecorrespondence on which lives depended was lost.
Also, there were many cases where commercial
communications were unable to connect because ofcongested cellular phone line traffic. Therefore,
communication gathering necessary for evacuationand grasping of the situation was delayed and thishindered precise gauging of the height of the tsunami
and relaying of the urgency of evacuation proceduresto the public. Back-up communication lines are criticalwhen both private communications and commercial
communications fail. Thus, it is necessary to set up
independent communication lines in order that we are
not dependent upon commercial communications.

Bibliography
1)

2)

3)
4)
5)

The Institute of Electrical Engineers of Japan : Technical
Report, No. 628, “Electrical Facilities Damage Condition of
Grate Hansin Earthquake”
The Institute of Electrical Engineers of Japan : Technical
Report, No. 775, “Earthquake Countermeasures of Electrical
Equipment at Public Facilities”
Nikkan Kogyo Shinbun Ltd., 2011, Vol. 11, “Environmental
Solution Special Impact : Eco-Smart Recovery”
Japan Sewage Works Association, Revision, June 2007 “Rules
Regarding disaster support in Sewage Works”
Ministry of Land, Infrastructure, Transport and Tourism :Sewage Works Earthquake/Tsunami Countermeasures
Technical Investigation Committee, Third Motion, “The Stateof Recovery of Sewage Facilities Damaged by the Great
Eastern Japan Earthquake”

Table 6. 1 Summary of the Damage Situation of Respective STPs
Ishinomaki Tobu STP

Power receiving point

Power receiving and transforming
equipment

Emergency generator

Water treatment facilities

Sen-En STP

DC power source/uninterruptible
power system

Instrumentation facilities

No damageTsunamidamageNo damage (Because located at elevation)

The power transmission lines of the power company
The leading-in poles were destroyed. (tsunami)
were destroyed. (tsunami)

The leading-in poles were destroyed. (tsunami)

The disconnecting switches were damaged. (open
No damagestructure)

No damageTsunamidamageInundated, tsunami (1st floor)

Inundated, tsunami (1st floor)

Inundated, tsunami (The electric room on the 2nd floor
is undamaged.)

Earthquake
No damagedamageNo damage

One set was broken due to the earthquake. (Although
it started, it later failed because the cooling water pipe No damage
was broken and the control power supply was lost.)

TsunamidamageInundated, tsunami (1st floor)

No damageInundated, tsunami (1st floor)

Earthquake Damaged. (in-house transmission/ communication
No damagedamageequipment)

No damageThe printers on the desks were moved slightly.

No damageTsunamidamageInundated, tsunami (outdoor, 1st floor, basement)

Inundated, tsunami (outdoor, 1st floor, basement)

Inundated, tsunami (outdoor, 1st floor, basement)

Earthquake
No damagedamageNo damage

Damaged.
(The LCD monitors were toppled and destroyed. The
No damageanchor seat for the power supply board for operation
was deformed.)

TsunamidamageInundated, tsunami (1st floor)
Inundated, tsunami (1st floor)
Inundated, tsunami (1st floor)(The dehydrator was on the 2nd floor, but the (The dehydrator was on the 2nd floor, but the auxiliary (The dehydrator was on the 2nd floor, but the auxiliarymachine on the 1st floor was inundated.)machine on the 1st floor was inundated.)
auxiliary machine on the 1st floor was inundated.)

Inundated, tsunami (1st floor)

The auxiliary machine was damaged.

Inundated, tsunami (outdoor, 1st floor, basement)

Inundated, tsunami (1st floor)

Earthquake
No damagedamageNo damage

No damage

No damageTsunamidamageInundated, tsunami (outdoor, 1st floor, basement)

Inundated, tsunami (outdoor, 1st floor, basement)

Inundated, tsunami (outdoor, 1st floor, basement)

Earthquake
No damagedamageNo damage

No damage

No damageTsunamidamageOnly the 1st floor in sludge building was inundated.
Other rooms (watertight doors) on the 1st and 2nd No damage
floors were undamaged.

Inundated, tsunami (1st floor)

Earthquake
No damagedamageNo damage

No damage

No damageTsunamidamageInundated, tsunami (outdoor, 1st floor, basement)

Inundated, tsunami (outdoor, 1st floor, basement)

Inundated, tsunami (outdoor, 1st floor, basement)

No damage

No damageThe printers on the desks were moved slightly.

No damage

No damage (installed on the 2nd floor)

No damage (installed on the 2nd floor)

Inundated, tsunami (outdoor, 1st floor, basement)

No damageInundated, tsunami (outdoor, 1st floor, basement)

Control device
Control panel
Operation system

TsunamidamageNo damage (installed on the 3rd floor). However, thecentral sludge treatment facilities on the 1st floor were No damage (installed on the 2nd floor)
damaged.

Earthquake
No damagedamageNo damage

No damage

No damageTsunamidamageInundated, tsunami (1st floor)

Inundated, tsunami (1st floor)

Inundated, tsunami (1st floor, basement)

The power receiving cables were damaged.
(The hand hole sagged.)――

The cables were damaged due to the subsidence.

Inundated, tsunami (1st floor)

Earthquake
No damagedamageOutside pump station

Communication equipment(wireless accident prevention system)

Tsunamidamage* The trunk flow meters were submerged (in about 18* Several of the 14 stations were inundated.
* The circuit was cut off (The service line poles for the places).
――* The circuit was cut off (The service line poles for the
NTT circuit were destroyed.)
NTT circuit were destroyed.)* Some pump stations were submerged.
――

The line was cut off during communication.

NormalUnaccounted-for water(immediately after the disaster)

30,000 to 40,000 m 4/day

Instrumentation functioned only in the Shiogama
Pumping Station.
Unclear
Usually it increased to 25,000 ® 30,000 m 3/day.

Unaccounted-for water(as of Nov. 2011)

10,000 m 4/day

Increased by about 10 to 20%.

Unclear

Remarks

No damage

Earthquake
No damagedamageEarthquake
No damagedamageCentral monitoring facilities

Kennan STP

No damage

Sludge treatment facilities

Common facilities

Minami Gamo STP

Earthquake
No damagedamage

The circuit was cut off (The service line poles for the
NTT circuit were destroyed.)

It could not be used because the power supply was lost.
Unclear

About 10,000 m 3/day

Some electric cables were damaged.

The storage battery was damaged (overdischarge)(excluding the Sen-En Purification Center).

The storage battery was damaged (overdischarge).

Table 6. 2 Summary of the Restoration Process in Respective STPs
Ishinomaki Tobu STP
Power receiving equipment

Temporary power generator/power receiving

Sen-En STP
Temporary power generator/power receiving

Minami Gamo STP
Temporary power generator/power receiving

Kennan STP
Temporary power generator/permanent power receiving

For in-house treatment : primary sedimentation+simple
disinfection (screen, temporary submerged pump, temTemporary sedimentation tank+simple disinfection byPrimary sedimentation+Simple
Primary sedimentation+Simple disinfection by solid
porary simple disinfection equipment)
Step 1 disinfection by solid chlorine
solid chlorine (temporary submerged pump, temporary
For wastewater not treated sufficiently : Wastewater is chlorine
simple disinfection equipment)(Temporary submerged pump)settled in the sedimentation tank installed temporarily in
the green park, disinfected simply and then discharged.
Primary sedimentation+disinfection (temporary sodium
Temporary sedimentation tank+simple disinfection byPrimary sedimentation+Simple
Primary sedimentation+simple disinfection (screen,
Restoration stage
hypochlorite injection equipment)
solid chlorine (screen, main pump. Temporary filter,Step2
disinfectionbysolid
chlorinemain
pump+permanent
sodiumhypochlorite
injection* The items in parentheses
Sludge removal+temporary sludge dehydration
temporary disinfection equipment)(Main pump+gate, screen, sludge removal equipment) equipment)
are equipment to which
Temporary power receiving
electrical power is supTemporary sedimentation tank+simple aeration+simple
Primary sedimentation+contact aeration
plied.
Primary sedimentation+simple aeration+simple disin- Primary sedimentation+disinfection (sodium hypochlordisinfection by sodium hypochlorite (screen, main pump,process+disinfection (main pump, temporary biological
Step 3fection (screen, main pump, simple aeration equipment, ite injection equipment) +contact aeration process+temporary filter, simple aeration equipment, temporary
treatment facilities, sludge removal pump, permanent
permanent sodium hypochlorite injection equipment)
sludge removal+existing centrifugal dehydrator
disinfection equipment)
sodium hypochlorite injection equipment)
Permanent restoration
Permanent restoration
Permanent restoration
Permanent restoration(Main pump, sludge removal pump, sodium hypochlorite (Power receiving and transforming equipment, screen, (Power receiving and transforming equipment, screen, (Power receiving and transforming equipment, screen,
Step 4
injection equipment, pure oxygen generator, electrical main pump, sodium hypochlorite injection equipment, main pump, sodium hypochlorite injection equipment, air main pump, sodium hypochlorite injection equipment,
blower)blower)blower)equipment for sludge treatment)
Sludge treatment* The items in parentheses are the Operation of sludge treatment was
equipment to which power is permanently restored.
supplied.
Recycled water

Instrumentation equipment

Central monitoring facilities
Others

1. Temporary dehydrator ® carried outside the facilities
Permanent dehydrator, temporary auxiliary machine ®
(collector, temporary dehydrator, chemical injection Some dehydrators were permanently restored.
carried outside the facilities→ carried outside the facilities (sludge removal pump,pump)(sludge removal/chemical injection pumps, centrifu2. The existing centrifugal dehydrator was restored → dehydrator)
gal/belt dehydrator
carried outside the facilities (collector, dehydrator)

The sand filter was permanently restored. For the pumpIndustrial water is purchased.
shaft seal water, influent was filtered simply and used.

No damageThe following were set up temporarily : pump well water
The water-level meters (influent ditch, pump well) andlevel for the main pump, discharge tank water level.
The influent flow meter was restored preferentially.
influent flow meters were restored. All the other
Sludge facilities : sludge storage tank liquid level,
instrumentation equipment was permanently restored.
temporary chemical injection tank liquid level.
The central facilities were undamaged. The central
Some damaged devices were replaced with new ones.
facilities of sludge treatment were permanently restored.
Sludge removal is performed by the telescopic gate.
(No power is required.)Part of the sand filter was permanently restored.
They restored the water level of the influent ditch andpump well, which is necessary for the operation of themain pump.
Some functions were restored by using the simple
monitoring device.
Power is supplied to the respective buildings via theelectrical room on the 2nd floor, which was undamaged.

Remarks

23

Chapter 7

EICA Report of the Great East Japan Earthquake Investigation

Proposal

EICA has conducted hearings and surveys about
the tsunami disaster areas in Tohoku (northeast)

make it certain.

Japan. Proposals from results and findings of thehearings and surveys will be covered in the following
paragraphs.

5．Shifting of important electrical and instrumentation systems to the 2nd floor

1．Securing information sharing and transmission
methods

affected by the tsunami. Therefore, it is important toshift installations such as central monitoring system,
water treatment process and sewage treatment

In times of emergency, effective collection andsharing of disaster information is important.
Therefore, there is a need to implement fiber-optic
wire transmission network installed in sewer pipe andcloud sharing information databases for sewage
treatment facilities.
2．Implementation of Business Continuity Plan
(BCP)
Implementing BCP and emergency manual protocol
allows problems of not only the times of disaster but
also current situation and solutions to be identified
easily. As for fallback operation of electrical andinstrumentation systems, it will be effective to review
BCP and document for such procedures.
3．Fallback operation of electrical and instrumentation system
During early stages of Great East Japan Earthquake
disaster recovery, many electrical rooms were affected by the tsunami. Such rooms was backed up by
separately located electrical rooms via temporary
installed cables, where demand power was provided.
At affected STPs, only the primary sedimentation
treatment process was operated as tempory sewage
treatment process, reducing the overall operation of
STP. Therefore, there is a need for fallback operationof electrical and instrumentation systems to be
developed.
4．Securing Power Supply
Usage of independent power supply such as solar
cell and emergency generator should be encouraged,
so as to reduce external power reliance. In times of
emergency, it is important to secure the minimal
power supply with independent power supply during
long periods of blackouts. And as final power supply, it
is important to install large scale storage batteries to

According to surveys conducted, installations thatwere located on the 2nd level were apparently notprocess monitoring systems, power supply systems,
emergency power supply systems, etc to the 2nd floor
to counter disasters such as tsunami, high tides andflooding. In addition, development of technical implementation methods of such installations on the 2nd
floor is needed.
6．Water-proofing installations for electrical andinstrumentation systems
Cases of installations with flood doors, situated on
the 1st floor, were discovered to be able to reduce theeffects of flooding. Installations which are unable to beinstalled on the 2nd floor should be provided with floodwalls, flood doors, etc. For such installations, wiring
shaft and pipe shaft should be tightly closed to prevent
inundation. Thus, there is a need to develop methodsof reducing the effects of floods on electrical andinstrumentation systems.
7．Power lines, signal lines, etc installed undergroundUtility poles supporting power lines, signal lines
were destroyed by the tsunami, resulting in power
disruptions and information disconnection. Therefore,
it is important to install the cables underground.
8．Prevention of over discharge of lead storage
battery
During disaster, there were many cases where leadstorage batteries of emergency power supply overdischarge and resulted in damages. Therefore, it isimportant to install warning devices where warning isgiven when storage batteries over discharge. In
addition, storage batteries should automatically shut
down just before or during times of over discharge.

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

24

9．Water-proofing of emergency generator system
Many emergency generator systems were dam-quake and blackout, when emergency generator
starts, staff should check local electric rooms in order

aged by the tsunami. Hence, it is important towaterproof not only generator itself but also auxiliary
units, for example fuel supply pumps. In addition, suchto confirm normal operation. But in the case of Great
East Japan Earthquake, on their way to check theelectric rooms, the tsunami hit the STPs.

units should be earthquake proof as well.
10．Prevention of buoyancy damage by tsunami

Consequently, it is found that there is a need to revise
the manual of emergency power supply procedure. In
addition, alarm system and sound system are needed

During disaster, at each STPs, huge digestion gas
tanks were damaged by buoyancy and washed away

to be installed so as to effectively direct people
concerned to safe evacuation zones.

by the tsunami. In addition, air pipes and respective
machines in pipe corridors were also damaged bybuoyancy of tsunami. Therefore, it is needed to install
suitable measures to prevent the damage of machines
by buoyancy. Technical review of protecting suchbuoyancy phenomenon by tsunami is needed as well.
11．Ensuring safety of staff after earthquake
It is important consider ensuring safety of STPʼsstaff. Fortunately, most of the people involved with
the STPs survived the tsunami by finding shelter inthe roof of the administration building. After earth-

12．Earthquake Procedure
Even though damage from this earthquake was notserious, procedures to handle earthquake disastersituation is still important. During Great East Japan
Earthquake, collapse of shelves, chairs, Liquid Cristal
Display (LCD) monitors disrupted monitoring operations in central control rooms of many STPs.
Therefore, it is needed to ensure and implement
measures where shelves, chairs, LCD monitors, etc are
firmly rooted.

25

EICA Report of the Great East Japan Earthquake Investigation

AfterwordFirst, a heartfelt thanks to all personnel from Miyagi
Prefectural Government and Sendai City Government
for the support given us during the disaster assessment held at the end of 2011. We have managed tocomplete this report with help in a questionnaire about
the disaster and the condition of restorations, hearings,
and STP investigation. To those who have done atremendous job in rehabilitating the devastatedsewage STPs to restore a decent level of operation, we
pay our highest respect for all your hard work.
By going through this investigative research, we
found that disaster can come in various ways.
Throughout the history of Japan sewerage works, wehave experienced various kinds of disasters such as
land liquefaction during Niigata Earthquake (1964), an
earthquake directly above the epicenter like Great
Hanshin Awaji Earthquake (1995), and NiigataChuetsu Earthquake (2004) which caused the uplifting of sewage manhole. Crisis comes one after
another. Now, for the first time, we have suffered theimpact of a tsunami on STPs during Great EasternJapan Earthquake.
The investigation was focused on electrical andinstrumentation control systems of 4 large scale STPs
in Tohoku district. We visited the sites and found outthat various types of damages had occurred at each
STP. Minami Gamo STP was directly hit by thetsunami while the Sen-En STP was swooped by sludge
mixed with water from the nearby Sendai Bay.

Photo. 1 A temporary monitoring control system of dehydrator
which consists of a notebook PC and instrumentation
attached to card box. (Date Taken : October 2011 at SenEn STP)

Because of this, different countermeasures had to be
applied on each restoration work. For example,
Photo. 1 shows a damaged site where an inventive
approach was needed to improve the conditions. They
were able to make a temporary monitoring control
system of the dehydrator in a short amount of time.
Photo. 2 shows a temporary sedimentation pond
which was designed based on the experience from
Niigata-Chuetsu Earthquake.
The fact that even the slightest difference inlocation can result in a totally different impact from a
hit of Tsunami should be a crucial hint for disasterprevention in the future.
Throughout our investigation we have found anumber of common grounds among all disaster cases.
First is the occurrence of severe power shortage.
Next is the fact that restoration work was oftentimes
harder than expected. Third, most people who
escaped into the administrative building were saved.
Finally, machines such as dehydrators and central
monitoring system which are usually located on the
2nd floor were hardly affected by the tsunami.
EICA has conducted the research based on theconditions described above, supporting rehabilitation
works in electrical and instrumentation fields whilelearning to prevent the same effects of disasters fromhappening again.
Because of the catastrophe from Great EasternJapan Earthquake which was caused mainly by the

Photo. 2 A temporary sedimentation pond and discharge pumpwas
installednear
thewatershedofthe
Kyuukitakamigawa River to treat sewage water rightafter the earthquake. (Date Taken : May 2011 at near
Ishinomaki Tobu STP)

Great East Japan Earthquake Investigation Committee The society of Environmental Instrumentation, Control and Automation (EICA)

massive tsunami, most of the research and investigation were focused on it. However, the tsunami was not
the only disaster that accompanied earthquakes. Lackof awareness on other prevention methods such as inground shake prevention could be fatal. Moreover, thepossibility of multiple impacts like land liquefaction,catastrophic fires and massive blackouts that happen
in major cities should also be considered.
Regardless of the kind of disaster, information

26

collection and resources for countermeasures against
disaster should be arranged and prepared, putting thehighest priority on saving human lives.
Torahiko Terada (1878〜1935), a well-known physicist in Japan once wrote, “The meteorology andgeophysical location of Japan is largely affected by theextremely unique environment surrounding it. As aresult, one shall never forget that we are bound to thethreat of catastrophe every single day.”