Implementation of Decontamination Projects
4.1. Overview of Decontamination
The areas to be decontaminated are areas that are necessary from the viewpoint of protection of humanhealth, and living areas such as residential areas, schools, parks, large Facility, roads, agricultural lands
and the like, as well as forests and areas within forests where people frequently enter.
In the decontamination process, MOE first determined the owners of the land and buildings to be
decontaminated, got consent for entry, conducted preliminary radiation monitoring, and investigated thecondition of buildings, etc. Based on the results, a decontamination plan for each property and building
was prepared, the method of decontamination was confirmed with the owner, etc., consent fordecontamination was obtained, and decontamination work was conducted.
After the decontamination work was implemented, radiation monitoring was carried out to confirm theeffectiveness of decontamination, and reporting was made to owners of land and buildings.

Figure 4-1 Flow of decontamination process
In implementing the decontamination projects, work was handled by construction contractors with knowhow based on extensive local work on large-scale projects, plus experience in securing and managing
workers. Investigative and design consultants were in charge of investigation of land and buildings,
radiation monitoring, supervision support and other matters.
For explaining to and obtaining consent from the land and building owners, etc., MOE was mainly
responsible for Special Decontamination Areas (SDA), while municipalities were mainly responsible forIntensive Contamination Survey Areas (ICSA), and decontamination contractors who worked on site also
responded to residents in various ways.
145

4.2. Preliminary Surveys and Obtaining Consent in Special Decontamination Areas
Preliminary Surveys and Formulation of Decontamination Plans

In order to prepare decontamination plans and obtain consent, first, research was done to identify the
persons concerned, such as land and building owners (persons who have the right to block theimplementation of measures such as decontamination on the property where measures such as
decontamination of soil, etc., are to be performed, or other fixed items such as trees). Residents in Special
Decontamination Areas had been evacuated under evacuation orders, and they were in various evacuation
destinations. In addition, there were many kinds of cases of ownership, and in many cases the landowners
were not clearly known. For example, there were cases in which one person concerned owned many piecesof land and buildings, cases in which one piece of land had a different name registered and separate ownerdue to inheritance, etc., cases in which the owner was deceased but the registration information was not
up to date, and cases in which a person other than the farm land owner was actually doing the farming
activities, etc.
For these reasons, to compile information on land and houses, the persons concerned were identified
with information from various sources, such as property registries, land and house records, and housing
and property maps, etc., while also obtaining cooperation from municipal authorities, heads ofadministrative districts, and land readjustment associations , etc.
In order to clarify details about properties for which consent was sought and to determine the magnitudeof decontamination required, the Ministry also compiled information on land and housing by indicating
the property boundaries of residential land (by land owner) and buildings on maps and aerial photographs.
In doing so, some cases were observed in which databases of land and housing based on geographic
information system (GIS) technology helped boost efficiency at subsequent stages when conducting fieldsurveys and preparing and distributing consent forms. There were also cases in which existing laser surveys
and GIS information intended for residents’ asset management were also utilized for the decontaminationwork.
駐車場駐車場

ｺﾝｸﾘｰﾄｺﾝｸﾘｰﾄ

芝生

芝生

Credit: Shimizu Corporation
Figure 4-2 Example of plotting of land and buildings using GIS

In order to clarify the details of places to be decontaminated in draft consent forms through photographsand drawings, etc., radiation monitoring surveys and damage surveys of buildings, etc., were conducted to146

serve as preliminary property surveys (field surveys) prior to decontamination work.
Since the decontamination method would differ depending on the target of decontamination as well as
the material and condition of the target surface, those factors were confirmed, and in radiation monitoring
surveys, measurements were done after representative measurement points were selected for each targetof decontamination in the survey areas.
In some cases buildings had been damaged by the earthquake disaster, etc. If the damage was significant,it could be difficult to conduct the decontamination work, so in order to determine (after decontamination)
whether a building’s damage had been caused by the earthquake or by decontamination, it was necessary
to create a record of the situation before the decontamination work, and to confirm that with the persons
concerned as well.
For this reason, architects and emergency risk appraisers conducted visual inspections of damage fromthe exterior of buildings and created sets of photographs for each building, etc., to be decontaminated.
For preliminary radiation monitoring and surveys of building condition, since it was necessary to enter
private property and other premises, consent for entry was obtained from the landowners, residents, orother persons concerned, and the surveys were conducted within the scope of consent obtained.
There were cases in which mapping information was loaded in advance into a portable digital assistant(PDA) equipped with GPS, and the information acquired at the site was then loaded into the PDA in realtime, in order to efficiently conduct the field surveys..

Based on the above, in terms of explanatory materials used when obtaining consent, for each person
concerned, work contractors prepared a “Diagram of the Current State of Buildings, etc.” describing theexternal appearance and status of damage of buildings, etc., and a “Decontamination Plan” document
indicating the buildings to be decontaminated plus the extent of land as well as the decontamination
methods.
Acquiring Consent
In implementing decontamination and other measures, actions were taken to obtain prior consent fromthe persons concerned, such as landowners, concerning the details of decontamination or other measures
to be implemented, based on Article 38 of the Act on Special Measures concerning the Handling ofEnvironment Pollution by Radioactive Materials.

Preparation of Draft Consent Form
In acquiring consent from persons concerned, it is necessary to indicate in writing the target and methodsof decontamination, plus other conditions, etc., and keep a record of consent. For this purpose, thefollowing documents were prepared: “Decontamination Plan” (Figure 4-3), “Present Condition
Confirmation Form,” (Figure 4-4) and “Decontamination Implementation Consent Form” (Figure 4-5).

147

Acquiring consent
In principle, the method of obtaining consent was to mail questionnaires on consent for decontamination
to the persons concerned, confirming the date of a site visit, etc., confirming the target of decontamination
on-site, and explaining the decontamination method, etc. However, if the person concerned was residing
outside the prefecture and would find it difficult to attend on-site, a visit was made to the home or place ofevacuation, or to provide an explanation by telephone.
The draft consent form was explained on-site and the content of the decontamination work was finalized.
In addition there was discussion and confirmation with the person concerned regarding detailed conditions
for doing the decontamination, such as things the person concerned wanted decontaminated in the living
areas (such as water courses, and access routes to ancestral shrines in hills near their homes), and things
they did not want decontaminated (such as significant yard trees and moss).
If as a result consent was obtained regarding the current situation of buildings and the Decontamination
Plan, the “Present Condition Confirmation Form” and “Decontamination Implementation Consent Form”
were completed, then sealed (endorsed).

Figure 4-3 Example of Decontamination Plan148

【機密性２】【機密性２】※機密性は以下を参考に、適切に変更・表示し、以下の記述を削除してください。
秘密文書相当、機微な個人情報を含む場合は【機密性３】
公開を前提としない場合は【機密性２】（公開前の案の段階なども含む）
公開可能な場合は【機密性１】※取扱制限等(例１：関係者限り、例２：公表までの間)については必要に応じて追加してください。

※機密性は以下を参考に、適切に変更・表示し、以下の記述を削除してください。
秘密文書相当、機微な個人情報を含む場合は【機密性３】
公開を前提としない場合は【機密性２】（公開前の案の段階なども含む）
公開可能な場合は【機密性１】※取扱制限等(例１：関係者限り、例２：公表までの間)については必要に応じて追加してください。

現況確認書

除染実施同意書

平成

甲

環境省福島環境再生事務所長

乙

住 所

年

氏 名

月

平成

日

甲

環境省福島環境再生事務所長

乙

住 所

年

月

氏 名

印

日

印

乙は、甲及び甲が委託した者が、乙が所有権等の権利を有する別表の所在地及び区分の土地、建物等に対して、別紙の除染計画書のとおり除染作業を実施することを同意します。

甲と乙は、乙が所有権等の権利を有する別表の所在地及び区分の土地、建物等の現況
が、別紙の現況図のとおりであることを確認します。
なお、除染作業の開始までの間に、別紙の現況と異なる点があった場合には、甲若し
くは甲が委託した者又は乙は、速やかに相手方に連絡し、両者の間で、現況の再確認を行います。甲又は甲が委託した者は、現況の再確認が完了するまでは、除染実施同意書に基づく除染作業は実施しません。

（同意に係る留意事項）
１．甲及び甲が委託した者は、除染作業の終了後、常緑樹の落葉等により再度除染が必要となった場合や「除染等の措置としての庭木等の伐採及び除去に係る損失補償基準」の要件に該当する場合には、更に除染（以下「追加的な除染作業」という。）を実施します。
２．甲及び甲が委託した者は、除染作業又は追加的な除染作業（以下「一連の除染作業」という。）に必要な範囲内で上記の所在地の土地に立ち入り、当該作業を実施するとともに、当該作業に必要な資機材の設置等の目的で上記の所在地の土地、建物等（以下「除染対象」という。）を使用します。当該作業が終了した場合には、速やかに設置した資機材の撤去等を行います。なお、除染対象の建物等には立ち入りません。
３．甲又は甲が委託した者は、一連の除染作業について、それぞれの作業の実施日及び終了日を乙に連絡します。
４．乙は、一連の除染作業が終了するまでの間において、除染対象に係る権利を譲渡する場合には、速やかに甲に連絡してください。また、当該権利の譲渡に当たっては、この同意の内容を当該権利の譲渡を受ける者に継承してください。

特記事項

特記事項

Figure 4-4 Example of Present Condition

Figure 4-5 Example of Decontamination

Confirmation Form

Implementation Consent Form

Posting in official gazette
In the Special Decontamination Areas, when the location of the persons concerned was unknown and theconsent could be obtained in the Special Decontamination Areas, in accordance with Article 38 of the Act
on Special Measures concerning the Handling of Environment Pollution by Radioactive Materials, thelocation of land to be decontaminated and decontamination methods, etc. are posted in the official gazette,
and in case there was no objection, etc., within three months from the date of publication, consent wasdeemed to have been obtained.
If the current landowner was unknown, there were cases in which the land in question was posted in theofficial gazette and confirmed for a certain period of time, but after a certain period of time, when threeparties (the landowner, MOE, and the contractor) were supposed to witness the site, the municipality would
attend in place of the landowner, and decontamination was implemented even with the landowner unknown.
In the case where a large number of persons concerned were involved, there were cases in which bycooperation of the government, a government witness replaced the landowner witnesses.

In order to obtain consent, it was necessary to identify and obtain consent from persons concerned who
have rights to the target of decontamination, regardless of whether they were in residence or in evacuation,
but there were potentially tens of thousands to hundreds of thousands of targets of decontamination, even149counting residential areas alone, and there were many cases of complex ownership and where thelandowners were unknown. In Special Decontamination Areas everyone was in evacuation.
Under such circumstances, it was necessary to obtain consent by investigating the registries, etc.,
identifying the persons concerned, determining the place of evacuation, explaining the current situation,and explaining the decontamination method.
When obtaining consent, detailed drawings were prepared in advance, as well as materials about
decontamination methods for each subject of decontamination, and careful explanations were provided toobtain consent. In explanation and consultation with residents, efforts were made to listen to the opinions
and requests of the residents, to discuss the work methods, etc., to answer questions and concerns, etc.,
until both sides were satisfied.
For cases in which residents had evacuated, such as Special Decontamination Areas, efforts were madeso that they themselves could confirm the decontamination work, such as obtaining the consent on site andallowing them to witness the decontamination work. Guidance and training were provided to contractors
and decontamination workers involved in obtaining consent, so that they could respond sincerely andestablish trusting relationships with the persons concerned.
There were also cases in which local workers who were themselves engaged in decontamination work
cooperated to facilitate an earlier start of construction work. For example, they helped to get consent by
obtaining information to reach evacuees through acquaintances.
Meanwhile, especially at the initial stage, decontamination methods and policies had not been decided
in some cases, so questions or requests from residents could not be answered quickly. Also, the process ofobtaining consent did not proceed smoothly in some cases, so it was not possible to start decontamination
work in those areas, resulting in complaints from persons concerned who had been early to provide theirconsent.
Regarding the decontamination of individual houses, it was important that the persons responsible forobtaining consent had a consistent understanding of things. Otherwise, exceptions could disrupt theconsistency of decontamination compared to other houses in the area.

Statistics on consent obtained
The trend for consent obtained in Special Decontamination Areas is shown in Figure 4-6, the number of
persons concerned is shown in Table 4-1. Consent was obtained from 31,085 people out of 31,326 persons
concerned, while consent was not obtained from about 241 persons concerned (as of the end of September2017).

150

Table 4-1 Persons concerned(Special Decontamination Areas)
(件数)
4000

100%

3600

90%

3200

80%

2800

70%

2400

60%

2000

50%

1600

40%

1200

30%

800

20%

400

10%

0

0%

3 6 9 12 3 6 9 12 3 6 9 12 3 6 9 12 3 6 9 12 3 6 9 12 3 6 9
2011

2012

2013
2014
monthly number
単月同意取得数

2015
2016
同意取得率（累計）total number (rate)

2017

Municipality
Tamura City
Naraha Town
KawauchiVillageOkuma Town
Katsurao
Village
Kawamata
Town
Futaba Town
Iitate Village
Tomioka Town
Namie Town
Minamisoma
City
Total

Persons
concerned(persons)
316
4,095
365
464
827
822
250
2,599
4,643
7,573
9,372
31,326

Figure 4-6 Trend of consent acquisition(Special Decontamination Areas)

Categories of reasons to withhold consent
An effort was made to obtain consent for decontamination from persons concerned in Special
Decontamination Areas, but consent was not obtained from some persons concerned. As a background tothis, knowledge on the influence and risk of radiation was not widely known at the time of the accident,
coupled with the repeated unclear explanations such as “no immediate impacts on the human body” about
the influence of radiation, so it is conceivable that people were anxious and harbored distrust of the national
government.
Table 4-2 Major reasons for withholding consent (Special Decontamination Areas)
Category

Major reasons for withholding consent

General· Dissatisfaction and distrust in decontamination and government policy.

Residential· Cannot understand the purpose of decontamination.
· Decontamination is meaningless unless the dose drops to zero.
· The dose will be high adjacent to Areas where Returning is Difficult, so decontamination
is a waste of effort.
· Have no intention to return, so decontamination is a waste of effort.
· Unable to manage own home after decontamination, so cannot give consent tolanddecontaminate.
· Do not want decontamination for the time being because damage to the house issignificant (no roof) and the property adjacent to the residential land is extensive inarea.
·Belief that there is no meaning in decontaminating only the area around the main151

Farmland,building.
- There is no point in only decontaminating 20 m radius around the target offorestdecontamination. If the entire forest will not be decontaminated, I will not give consent.
· I question whether inversion tillage will make the dose drop. It does not make sense, so
I cannot give consent.

Temporary· Since no Temporary Storage Site has been decided, I cannot give consent.

Storage
Sites
Compensati· Will not give consent for decontamination unless compensation issues with TEPCO areonresolved.
Note) Typical reasons to withhold consent in Special Decontamination Areas are indicated, including cases
where consent was eventually obtained.

Column“Acquiring consent for decontamination projects” Fukushima Regional Environmental
OfficeDecontamination was implemented under the assumption that consent would be obtained fromlandowners or other persons concerned. However, it was extremely difficult to obtain consent, especiallyat the beginning, in the context of anger toward the TEPCO Fukushima Daiichi nuclear power station
accident and the lack of knowledge about decontamination.
Acquisition of consent in Special Decontamination Areas (SDA) was carried out sequentially with
Tamura City first, then Kawauchi Village and Naraha Town. In Tamura City, personnel from the
Fukushima Office for Environmental Restoration (now Fukushima Regional Environmental Office)obtained consent directly between June and August 2016 from about 300 landowners and other persons
concerned. In Kawauchi Village, officials of the Fukushima Office for Environmental Restoration
obtained consent from half of the persons concerned. To accelerate the obtaining of consent, once themethod was established the remaining work to obtain consent in Kawauchi Village was contracted out.
The work was also contracted out for Naraha Town and other municipalities.
At the start of decontamination, etc., MOE explained at briefings for residents that it would be seeking
consent. Initially, residents were very angry and anxious, and it was not an atmosphere conducive to
explaining matters, so we held many briefing sessions.
To obtain consent the Fukushima Office for Environmental Restoration set up a system of having teamsof two persons, having one experienced active or retired municipal employee paired with one individualfrom the private sector, going to meet with each person concerned and speak about decontamination.
They obtained consent by explaining the decontamination method based on each location. If the person
concerned was elderly, an attempt was made to be as straightforward as possible with the language used
to explain.
When work was contracted out to obtain consent, until around 2013, personnel from the Fukushima

152

Office for Environmental Restoration also accompanied the persons tasked with obtaining consent, andbesides obtaining consent, they also presented briefings and training sessions using guidebooks, question
and answer compilations, and decontamination consent forms, all in an effort to encourage conscientious
and suitable efforts.
In one municipality, no progress was made at all immediately after efforts to obtain consent began, but
at last, after repeated explanations, consent was obtained for just two administrative districts, anddecontamination of houses was performed. Because the administrative districts happened to be along amain road, people from other districts were able to observe decontamination being performed, which
promoted an understanding of decontamination, and then progress obtaining consent was made in otheradministrative districts as well.
Also, when difficulties were encountered in obtaining consent, personnel from the local municipality
accompanied personnel from the Fukushima Office for Environmental Restoration, and that helped
immensely.
In the future, decontamination will continue even in Areas where Returning is Difficult, so we willcontinue with efforts to carefully and sincerely obtain consent.

Monitoring Surveys

The air dose rate and surface dose rate of gamma rays were measured mainly using a scintillation typesurvey meter, at heights of 1 cm, 50 cm, and 1 m. To measure the degree of contamination of the target of
decontamination, the surface contamination density by beta rays from the surface was measured using a
GM survey meter.
In order to confirm the degree of contamination of the target of decontamination and the effects after
decontamination, measurements were made using a collimator (having cylindrical shielding material withlead, etc.) so as not to be affected by surrounding radiation.
When measuring the air dose rate, a radiation survey meter that satisfies the performance andrequirements specified in JIS Z 4333 is used. When measuring the surface contamination density, themeasured count rate (cpm) is recorded using a radioactive surface contamination survey meter that meetsthe performance and other requirements prescribed in JIS Z 4329.
Measurement of radiation dose is to be done in dry state in principle, in order to suppress the shielding
effect by moisture.

153

Scintillation type survey
meter

GM survey meter

Collimator

Measurement of surface
contamination density

Measurement of
air dose rate

Figure 4-7 Measurement instruments and methods
Source: “Decontamination Guidelines, May 2013, second edition (supplemented in September 2016)”(MOE)

In measuring air dose rates and surface dose rates, there were cases of utilizing an air dose ratemeasurement system with wearable GNSS (Global Navigation Satellite System). This enabled equipment
to be reduced to one-fifth the original weight, and the radio transmission of measurement data made it
possible to have just one person serve as both guide and recorder. Thanks to GIS, it increased work
efficiency by a factor of ten with high speed guidance with car navigation sensing, and enabled thevisualization of measurement results and progress of decontamination work.
In addition, a gamma camera was developed that makes it possible to visualize radiation by color-coding
high or low radiation levels in a captured image. This made it possible to visualize radiation, which isotherwise invisible, and contributed to the confirmation of the effectiveness of decontamination and thesafety of Temporary Storage Sites.

154

Credit: Kazima Corporation

Figure 4-8 Example of an air dose rate measurement system with a wearable Global Navigation
Satellite System

Figure 4-9 Example of a gamma camera

155

Figure 4-10 Example of image taken by gamma camera
Source: Reconstruction Agency, MOE, Fukushima City, Koriyama City, Soma City, Date City
“Exchange of opinions with experts on decontamination: Thinking from past experience by
the national government and four cities - Fact Book “(August 1, 2014)

JAEA has developed a “Calculation System for Decontamination Effect (CDE)” as a system to predict
the air dose rate after decontamination and evaluate the decontamination effects. This system wasdeveloped as a system to estimate and evaluate the air dose rate before and after decontamination and toevaluate the effect of decreasing the dose rate by decontamination, and by using the general purpose
software Excel it has become a system that many people can utilize. In addition to developing a“Restoration Support System for Environment” (RESET) that allows predictive evaluation of
decontamination effects on a simple operation screen on the Internet, for use in municipalities in Special
Decontamination Areas and Intensive Contamination Survey Areas, JAEA also makes predictions for thenational government, municipalities, etc., and the findings are used to provide advice and technicalguidance concerning decontamination implementation.
There is also a 3D decontamination effect prediction system developed by TEPCO and major
construction companies. They use analytical technologies that read quantitative decontamination resultsfrom examples of decontamination work and predict decontamination effects based on realistic conditions(consideration of terrain and sky shine, etc.). They made it possible to predict the effects ofdecontamination work and explain the actual results, and helped to facilitate efforts to obtain consent fromresidents.

156

Air Dose Rate
空間線量率(μSv/h)

Example of Analysis by [Dose 3D Map]
「Dose
3D Map」解析例(BeforeDecontamination)（除染前状況）(AfterDecontamination)（除染後予測）Credit: Shimizu Corporation
Figure 4-11 Example of 3D decontamination effect prediction system

4.3. Methods of Decontamination Work
Basic Principles of Decontamination and Overview of Decontamination WorkThe decontamination work is mainly to remove soil and sediments containing radioactive materials. It
also includes washing with water. For this reason, it is necessary to prevent contamination from removed
soil, sediment, waste water after washing, etc., in places where decontamination work has been completed.
Basically it should be working from top to bottom, to the extent possible. In residential areas, work is donein order, from removing branches of trees that are higher than the roof of a house, then working on roofs,
upper floors, lower floors, and yards. In sloping forests, this meaning working from the top to the bottomof the slope. Likewise, for roads the work goes down from the top of the slope, and finally decontaminates
the roadside gutters. If removed soil, etc., is to be transported, the road is cleaned and the roadside gutters
are decontaminated after the transporting is done. Work plans were formulated based on these principles.
In terms of regional units as well, it is desirable to work in order, from areas at higher elevations to lower
elevations, but in reality, in order to quickly proceed with decontamination, it was decided to implement
decontamination starting with those areas where consent had been obtained and Temporary Storage Sites
were secured.
In the Decontamination Guidelines “Guidelines for Decontamination and Other Measures, Second
Edition” (MOE), important points for decontamination and other measures are indicated as follows.
① Take the necessary steps to protect the health of the surrounding residents and conservation of theliving environment by taking measures such as prevention of scattering and discharge, prevention of
offensive odors, noise, and vibration, etc., and record the amount of soil removed.
157

② In order to effectively reduce the radiation dose by decontamination, it is necessary to identify
contaminated locations at a relatively high concentrations that contribute to the radiation dose, and todecontaminate in an appropriate manner depending on the characteristics of contamination. In addition, it
is necessary to verify the effects by taking measurements before and after decontamination, and effectively
reduce the radiation dose in the people’s living environment.
③ In order to prevent the removed soil, etc., from mixing with other materials, it is necessary to keep
removed soil and decontamination waste separate to the extent possible.
④ It is important to try to reduce the amount of removed soil generated by decontamination work and it
is also important to prevent the spread of contamination that might arise by doing decontamination work.
For example, washing with water produces waste water containing radioactive substances. Thus, to theextent possible and as appropriate, contractors are expected to remove radioactive substances by methods
other than washing with water, in order to avoid impacts where the water would flow. Furthermore, when
it is deemed necessary in consideration of the actual circumstances of the area, regular monitoring will be
carried out after such measures.
In addition, the following remarks are indicated in “Common Specifications for Decontamination andOther Work” (MOE) and “Technical Guidelines on Decontamination Operations” (Fukushima Prefecture).
· For decontamination, the sequence for efficient work is “from top to bottom” and “from upstream todownstream.”· Decontaminate in sequence of yard trees, roofs, rain gutters, yard areas, etc., in consideration of the
spread of contamination from decontamination work.
· To prevent re-contamination, perform work in order from high to low positions.
· Work should be conducted from upstream to downstream in the water gradient, to avoid scattering wateraround.

158

The decontamination methods in Special Decontamination Areas are stipulated in “Common
Specifications for Decontamination and Other Work” for each land classification and target of
decontamination. The main decontamination methods are shown in Table 4-3.
Table 4-3 Main decontamination methods
Classification
Residential
area etc.,
school, park,
large facilities

Road / Slope

Subject todecontamination
Roof · rooftop
Exterior wall · moat
Rain gutter
Yards,
Unpaved·grounds
surfaces

Paved
surfaces
Playground equipment
Paved roads

Unpaved roads

Guardrails
Roadside gutters, etc.
Footbridges
Roadside trees

FarmlandSlopesPaddy fields / fields

Pastures
Waterways
LeveesGrassland · strips

Main decontamination method (choose the appropriate method)
Removal of sediment / wiping / brush wash / high pressure water
wash
Wiping / brush wash / high pressure water wash
Removal of sediment / wiping / high-pressure water washing
Removal of sediment / weeding / lawn mowing / deep cutting of grass /stripping of grass / laying of new turf
Gravel and crushed stones cleaning by high pressure water / removal andcovering of gravels and crushed stones removal of topsoil at drainage
points under eaves / removal of topsoil near the root of trees / scrapingof surface soil / coating / inversion tillage
Trimming of yard trees - planting / logging and stumping of obstacle
trees / restoration of yard soil
Removal of sediment / brush washing / high pressure water washing /scraping / blasting / extra high pressure water washing
Wiping / cleaning / scraping
Removal of sediment / high pressure water washing / scraping /blasting / extra high pressure water washing / cleaning with a roadsurface cleaning vehicle
Weeding / removal of sediment / scraping of topsoil / covering /inversion tillage / high pressure wash of gravel and crushed stone /gravel · crushed stone removal · coating
Brush cleaning / high pressure water cleaning / wiping
Removal of bottom sediment
Removal of sediment / high pressure water cleaning / wiping /brush cleaning
Removal of sediment / weeding / removal of topsoil near the root /delimbingRemoval of grass · fallen leaves · sediment
Weeding / scraping of topsoil / mixing with water and removal ofsoil / inversion tillage / deep plowing/ deep tillage / willow tree
cutting down, chipping,· root removal, pulling out / clear cutting of
bamboo / logging of obstacle trees · root cutting / additional soil /cutting and removal of shrubs / soil restoration, fertilization
Weeding / scraping of topsoil / deep plowing / deep tillage
Removal of bottom sediment, etc.
Removal of sediment / weeding / scraping of topsoil
Cutting of shrubs / thinning of bamboo

159

Orchards

ForestRemoval of sediment / weeding / peeling of rough bark / highpressure water washing of bark / pruning of fruit trees / cutting
down, root cutting / scraping of topsoil · excavation
Removal of organic residue /sorting of cuttings/ pruning of
coniferous trees / cutting and removal of undergrowth and shrubs /removal of organic residue sediment160

Decontamination of residential areas and large facilities
In buildings such as houses and large facilities, in order to prevent the spread of contamination such as
through scattering and discharge due to decontamination, decontamination was carried out in order, from
top to bottom, from roofs, to rain gutters, exterior wall, fences and playground equipment, and yards, toroadside gutters, etc.
On roofs, work included removal of sediment, wiping, and brush washing, and on concrete roofs, highpressure water washing was also done. Rain gutters were cleaned with high pressure water, etc., while
exterior walls were wiped off, brushed and washed with high pressure water.
After wiping off fencing and playground equipment, etc., in the yard, work included removing sedimentin the yard, weed removal, and topsoil scraping, etc. were implemented. When topsoil scraping was done,
new soil was applied.
In the Intensive Contamination Survey Areas, partial decontamination of places with high air dose rate
was carried out based on the results of preliminary radiation monitoring.
When decontamination was carried out, an effort was made not to damage buildings, and if it was alocation with extensive damage due to the earthquake disaster could not be decontaminated due to being a
thatched roof, etc., the target and method of decontamination was determined after discussion with theowner.
Also, as time passes after decontamination, radioactive substances that had adhered to roofs and exterior
walls, etc., tend to flow out due to rain, etc., and tend to accumulate in rain puddles and below vegetation,etc., so decontamination was conducted accordingly.

Figure 4-12 Basic flow for the decontamination of buildings and other structures
Source: MOE “Decontamination Guidelines, Second Edition” (supplemented September 2016)161

Credit: Kajima Corporation
Removal of sediments

Credit: Taisei Corporation
Wiping off

Credit: Maeda Corporation
Brush cleaning

Credit: Maeda Corporation
Removal of gravel and crushed stones

Credit: Maeda Corporation
Removal of gravel and crushed stones

Credit: Obayashi Corporation
Scraping of topsoil

Credit: Taisei Corporation
Covering with topsoil

Credit: Okumura Corporation
Covering

Figure 4-13 Status of decontamination of residential areas and large-scale facilities
162

Decontamination of roads, etc.
On roads, work was implemented in order, from road surface to roadside gutter, etc. to prevent the spreadof contamination such as scattering and runoff due to decontamination and the generated wastewater was
subjected to wastewater treatment.
After sediments were removed, the pavement surface was decontaminated by high-pressure water
washing, extra-high pressure water washing, blasting or the like, depending on the state of the surface andthe contamination situation. Due to the large area of pavement surfaces such as roads and parking lots,
various technologies were developed to efficiently decontaminate, such as high pressure washing trucks
for road surfaces that were upgraded from high pressure washing trucks.
On unpaved surfaces, work performed included sediment removal, weeding, scraping of the topsoil, highpressure water washing of gravel and crushed stone, etc.
In addition, road structures such as guardrails were wiped and high pressure washed with water, and forsurfaces, sediment removal and weeding were carried out. After this decontamination was completed, work
performed included cleaning of road surfaces and removal of bottom sediment of roadside gutters, etc.

Figure 4-14 Basic flow of road decontamination
Source: MOE “Decontamination Guidelines, Second Edition” (supplemented September 2016).

163

Credit: Taisei Corporation
Wiping off

Credit: Taisei Corporation
High-pressure water washing

Credit: Taisei Corporation
Brush cleaning

Credit: Taisei Corporation

Credit: Maeda Corporation
Credit: Maeda Corporation
Blasting
Extra high-pressure washing
Figure 4-15 Status of decontamination of roads
Decontamination of agricultural landOn agricultural land, once it has been cultivated after a disaster, it is not practical to scrape off the topsoil,
as cesium that had been deposited on the surface becomes diluted and dispersed in the soil of the cultivatedfield.
For this reason, farmland use was included in the Intensive Contamination Survey Areas, etc., and inplowed farmland, inversion tillage and deep tillage were performed. In these agricultural lands, steps weretaken such as fertilization with potassium in order to address issues of absorption into crops.
On agricultural land that was not cultivated, such as in evacuated areas, after removal of sediments,
topsoil was scraped off. Even in evacuated areas, where the doses were low, decontamination was done by164inversion tillage and deep tillage, which do not require soil removal. Technical document of the Ministryof Agriculture, Forestry and Fisheries about agricultural land decontamination measures shows forinversion tillage if radioactive cesium concentrations in the soil are lower than 5,000 Bq/kg, and for topsoil
scraping if above that. However, for relatively low concentrations in agricultural land in Special
Decontamination Areas, MOE suggests deep plowing and deep tillage, and in other areas, topsoil stripping.
In agricultural lands where some time had passed since the accident, the land became overgrown withshrubs and brush, making it necessary to have root removal, and additional soil was needed as analternative to topsoil scraping.

Figure 4-16 Basic flow of decontamination of Farmland
Source: MOE “Decontamination Guidelines, Second Edition” (supplemented September 2016).

165

Credit: Maeda Corporation
Credit: Shimizu Corporation
Manual weeding, mechanical weeding, mechanical bundling etc.

Credit: Shimizu Corporation
Topsoil scraping

Credit: Okumura Corporation
Additional soil

Credit: Hazama Ando Corporation
Credit: Shimizu Corporation
Topsoil scraping and collecting using specialized equipment

Credit: Okumura Corporation
Deep tillage

Credit: Obayashi Corporation
Inversion tillage

Figure 4-17 Status of decontamination of agricultural land166

Decontamination of forests① Measures including decontamination of neighboring forests of residences
Regarding forests in the vicinity of residences, etc., from the viewpoint of reducing the radiation dose in
the living environment of residents, measures were conducted within about 20 m from the edge of theforest edge near residences.
In forests, after removing undergrowth and brush, fallen leaves and other organic residue was removed.
In forests where some time had elapsed after the accident, radioactive cesium had migrated under fallen
leaves and other residue, so in some cases simply removing organic residue would not be effective enoughfor decontamination. In such cases, where trials have been proven effective, residue (humus soil directly
beneath fallen leaves and organic residue) was removed using tools such as bamboo brooms to a distanceof 5 m from the edge of the forest. In the process, care was taken not to overly expose the roots of plants,from the viewpoint of preventing soil runoff.
In evergreen coniferous forests such as cryptomeria and Japanese cypress, radioactive cesium could still
be attached to some branches and leaves because the needles usually fall over the course of about three orfour years and large differences arise depending on the forest condition. In such cases, branches and leaves
were removed from standing trees at the forest edge, as necessary.
In addition, when re-contamination has been confirmed as a result of soil runoff over time from foreststhat have a low ratio of soil coverage by organic residue and forest floor vegetation and have a steep
gradient and high degree of contamination, the necessary countermeasures are carried out (e.g., installing
wooden fences, etc.).

Figure 4-18 Basic flow of forest decontamination
Source: MOE “Decontamination Guidelines, Second Edition” (supplemented September 2016)
167

Credit: Okumura Corporation
Removal of residue

Credit: Okumura Corporation
Conifer tree pruning

Figure 4-19 Status of Forest Decontamination

MOE

Ground surface
after removal of organic residue
Removalof organic residue by metal rake
鉄熊手により堆積有機物を除去。
堆積有機物除去後の土表面
Figure 4-20 Example of removal of organic residue such as fallen leaves

MOE

堆積有機物の除去の後に、Removalof residue by bamboo broom* after
removalorganic residue
竹箒＊ofにより残さを除去。
* Cut
to about 20 to cm to ensure flexibility of tip.
＊先端20cm程度をカットし弾力性を確保したもの。

Groundsurface after removal of organic residue
堆積有機物残さ除去後の土表面(roots start to be exposed).

（根が露出し始め）

Figure 4-21 Removal of organic residue and residue

168

Credit: Kawauchi Village
Fig. 4-22 Example of measures including decontamination of forests (measures to prevent soil runoff)② Decontamination measures for forests where people frequently enter
Regarding locations where people routinely enter forests such as satoyama near residences, considering
the specific needs of the local people and from the viewpoint of reducing the additional radiation dosetaking into consideration the site conditions, decontamination is implemented after considering the scopeand method of implementation. Specifically, decontamination is to be implemented properly after
considering factors such as the frequency of access and time typically spent, and the risk of soil runoff,etc., especially in recreational areas and where there are many opportunities for people to enter the forest,
such as mushroom farm, charcoal making, campgrounds, walking paths, hiking path, forest roads, rest
areas, open areas, and parking lots, etc.
Regarding forest areas where people frequently enter, as necessary, remove organic residue such as fallen
leaves, remove organic residue, remove branches and leaves of standing trees, and implement measures toprevent soil runoff. This is done taking into consideration air dose rates, frequency of access and time
usually spent at each facility (or for each section of the facility, as necessary), in accordance withdecontamination measures in forests near residential areas, and after deciding on the effective range offorest decontamination based on test work.

169Decontamination of forests where people routinely enter.

Figure 4-23 Basic flow of decontamination and other measures in places where people frequently
enter the forest
Source: MOE “Decontamination Guidelines, Second Edition” (supplemented September 2016).

170

Decontamination of reservoir
For decontamination by scraping bottom sediment from reservoir, considering the possibility that moreradioactive cesium may be present below the surface layer, efforts were made to avoid producing an
excessive amount of removed soil, etc. To do so, the thickness to remove was determined by scraping off
several centimeters at a time at the appropriate places in the pond while measuring the surface
contamination density.
In addition, sediment had to be scraped to the extent that decontamination would be effective in reducing
the air dose rate in the surrounding living environment. However, if there was a possibility that the air dose
rate in the surrounding living environment could be affected in the future by the flow of water into or outof the pond after decontamination, as necessary, decontamination of the bottom sediment was conducted
on an scale that was appropriate considering the possibility of sediment transport within the pond. This
included locations where there was no current impact on the air dose rate in the surrounding living
environment.

Figure 4-24 Basic flow for the decontamination of sediment in reservoir
Source: MOE “Decontamination Guidelines, Second Edition” (supplemented September 2016).

171

Preparation of work plans
The Common Specifications for Decontamination and Other Work indicate decontamination methods
and other matters for each target. Prior to commencing work, decontamination contractors prepared overall
work plans that cover all procedures and methods required to complete their work, and submitted them tosupervisory.
Test work
The work methods for decontamination depend on the situation on-site as well as the material and surface
condition of the target of decontamination, so it is impossible to uniformly design an optimum work method
and work conditions. For this purpose, test work was conducted in advance in order to decide the mosteffective decontamination procedures.
For example, test work was conducted in actual site conditions and decontamination methods were
decided based on reviews by supervisory personnel at MOE. Examples include the number of wipes neededin wiping operations, the depth and speed of deep tillage, and the rate of advancing of high-pressure roadsurface washers, etc.
Implementation of decontamination work
Decontamination work was implemented based on work plans. After implementation, reports wereprepared to summarize the work results, and the persons responsible for the work verified that it was done
properly based on the report and submitted the results to supervisory personnel at MOE.
Attendance by residents
Regarding Special Decontamination Areas, since the residents had evacuated and were therefore absent,
when decontamination work was to be done the schedule was provided in advance to persons concerned sothat they could attend and observe if they wished to do so. This approach encouraged persons concerned tounderstand the work situation of decontamination, and confirmed on site the matters that required
confirmation.
Confirmation surveys
Confirmation surveys were carried out after decontamination work to confirm whether work had been
performed properly. For example, proper wiping and washing are difficult to determine only by visualinspection after decontamination work, so supervisory personnel from MOE would randomly select asample section of a surface and have the workers repeat work there using the same method. It could thenbe confirmed whether or not a reduction in the surface dose rate could be observed comparing before andafter the decontamination work.
Measurement of the radiation dose in confirmation surveys was carried out before and after
decontamination by using a collimator (using lead as a tubular shielding material) to calculate the air doserate, etc., at a height of 1 cm, measured using the same measuring equipment before and after.
Work process and progress management
From the start of work to completion, decontamination contractors are required to complete a daily work
report, making note of the weather, work location, work description, number of workers, work progress
quantities, work equipment, and radiation doses in the work area, as well as instructions, approvals, and172

consultation items, etc. The reports include photographs to record the work, and checklists on the results ofdecontamination measures.
It was decided to use photographs of work as a means of work management. Based on photographmanagement standards, photographs are taken at each stage of work and after work completion, showing
work conditions in locations that cannot be visually inspected, work progress measurements, quality control
status, and disaster photographs of work in progress, etc. The photographs are to be stored properly andsubmitted when work is completed.
In addition, for work categories with numerical specifications listed in documentation on Common
Specifications for Decontamination and Other Work, measurements are taken based on the items andstandards for measurements specified in work progress control standards. The design values and actual
measurements are compared and recorded, and compiled in work progress control charts and tables.
At the beginning of the full-scale decontamination work, there were decontamination methods that usedvarious existing techniques and proposals for new materials. Test work was conducted using many work
methods, equipment and materials, and after evaluation and repeated refinements, they were adopted as
new techniques for use at decontaminations sites. Many of these work methods were incorporated
sequentially during revisions of documentation on the Provisional Quantification Standards for
Decontamination Work.
Changes in work methods over time
The decontamination techniques used for decontamination work in Special Decontamination Areaschanged as time elapsed after the accident. For paved road surfaces, a certain degree of decontamination
was achieved initially, but as time passed, cesium migrated deeper, so the effective method was no longer
to clean the surface but to use blasting to cut the pavement surface.
Also, as time passage after the accident, weeds grew in the soil of yards of homes and other properties
and on unpaved roads, and brush and shrubs grew in fields, resulting in an increase in work for the weeding
and cutting of brush and shrubs, compared with the initial decontamination work, etc.
Processing after topsoil scraping
Topsoil scraping is effective for dose reduction, but it takes a certain amount of time for the bare groundto recover. Particularly, when this is combined with heavy rainfall, the result could be the runoff of surface
soil or slope collapse, so until the vegetation is restored, in some cases blue sheets were used to cover andprotect the ground as a short term response measure.
For decontamination in residential areas, when the heavy rain fell on sloped land there was some runoffof additional soil material (mountain sand) whose original shape was restored after being scraped, so work
had to be repeated in some cases. To prevent recurrence, it was decided to use crushed stone for about 2 mdownstream to prevent the discharge of mountain sand from residential land.
Soil amendment of removed soil
For decontamination of agricultural land in Special Decontamination Areas, when scraped soil was put
into a large container bags and transported to Temporary Storage Sites, the contents liquefied (turned to173mud) by vibration, so the bags could not stand alone at Temporary Storage Site, and could not be stacked
in some cases. As a countermeasure, soil amendment was considered, and attempts were made to stabilize
the stacks at Temporary Storage Sites by using gypsum as a hardening material, with no impact on
agricultural land.
Supplemental decontamination
Although the air dose declined due to wide area decontamination, supplemental decontamination was
done in cases where localized high-dose locations were found, such as rain puddles, rainwater drain outlets,
roadside gutters, surface edges of paved and unpaved roads, under vegetation, on slopes and on flat surfaces,etc.
As an example in a Special Decontamination Area, if a filter drain or the drain itself had deteriorated,the drain was removed, the bottom material excavated and removed, and the components reinstalled or
replaced with new ones. Because more space was required for the reinstallation, the diameter of excavation
was expanded. If there was a source of contamination in connecting pipes, the pipe was removed startingfrom the level of the connecting pipes in a downward direction and horizontally until the dose decreased.
Responding to persons concerned
Decontamination contractors adjusted their responses for persons concerned when deciding methods
and targets of decontamination. There were various inquiries and requests from persons concerned. In
response, while reporting to and consulting with MOE and other clients, the consultants strove to build
positive relationships and respond, to the extent possible and within the scope of the decontamination work.
On the other hand, certain problems also arose. In the case of decontamination of houses, work was
performed after checking with the persons concerned regarding the work method and what to leave behind,but in the decontamination of planted trees, for example, in some cases problems arose when the contractor
cut down plants and trees that the owner had felt were important, because contractors could not distinguishbetween them.
In agricultural land decontamination, in some cases persons concerned requested that paddies be
converted to crop fields or that improvements be made to access roads. In such cases, the contractors
responded while consulting with MOE and local governments.

174

Column“Challenges and solutions in decontamination work”
Mr. Shigemi Kumagai, Kahoku Kensetsu, Inc. (subcontracted by Hazama Ando
Corporation)

The decontamination work requires steps be taken prior to the start of work, suchas radiation dose monitoring and confirmation of decontamination details withlandowners. Even after starting the work, there could be changes in the details andmethods while work is under way. It was stressful at times, as an effort was needed
for problem solving. In Namie Town in particular, all of the landowners had been
evacuated, so it took a long time to contact them and confirm things.
In the work of stripping contaminated soil on residential land, after the decontamination work, thedose was measured and if there were still spots with a high dose the work had to be redone, but first wewould have to wait for a decision on the depth and extent of work.
In the decontamination of the residential land, it was important to be considerate of landowners. We
could not handle items on the property without the landowner’ permission, and some items were full of
memories for them even if covered with dust. There were also fragile items, and we had to handle themcarefully. Also, there was manual work scraping off soil in confined spaces, so persistence was required.
However, there were times when landowners returned to check on the decontamination work andshowed their appreciation when they saw their homes looking clean. That gave us the strength to keep on
going.
For decontamination of agricultural land, we would restore levees (between fields), and there weretimes when local farmers would work together with us using their own specialized farm equipment. The
sense of unity was improved through working together, making it easier for people to understand eachother.
For some workers this was the first time doing construction-related work. Some did not take thedecontamination work seriously and only lasted a few days on the job. Also, some did not have expertisein civil engineering terminology, equipment types and functions, and did not understand things that I
thought should have been obvious. Initially I couldn’t see why they could not understand. For work that
required certification, there were operators who despite being certified lacked operating experience, sowork did not proceed as well as I expected, or something occurred that made me fear for an accident.
There was also guidance from joint ventures and they also assigned personnel and provided training
based on each person’s ability, so I think that things improved
considerably.
In Namie Town, some places returned to looking like abandoned
land, as some property was neglected when it took one to five years
after decontamination for the evacuation orders to be lifted.
Evacuation orders were only recently lifted, but it seems that many of
the returnees are elderly. I really hope that farming will resume,
young people will return, and that this once again becomes a vibrant town.

175Column“Challenges and solutions in decontamination work”
Mr. Yusuke Suzuki, Soso-Retec KK (subcontracted by Shimizu Corporation)

The most difficult thing when I first started doing decontamination work was thegap between my own pride and sense of value for this work versus the evaluationfrom the public.
Also, many workers came from various places and there were age differences. It
was hard to build team spirit, but I felt that it was the most important to facilitate thedecontamination work. I also learned the importance of working with an appreciationof the feelings of landowners.
I am from another prefecture, but I got married in Fukushima and we are now living here withchildren.
For the children, I want to make an effort to do decontamination work for the reconstruction andrestoration of this place, Fukushima.

Column“Challenges and solutions in decontamination work”
Mr. Yoshinari Itagaki, Kajimaroad Co, Ltd. (subcontracted by Kajima Corporation)

After October 2013 I was in Tamura City engaged in decontamination work under
the direct supervision of MOE, and I was currently performing decontamination workin Tomioka Town.
A difficult point was at the beginning when due to the rapid recruitment of workers,a large number of them were nearly amateurs so we had to begin by telling them how
to hold and use a shovel. To reduce radiation doses it was sometimes necessary to
decontaminate the same spot two, three, or more times. However, since the work itself did not require
high technical skills, within about a month they had learned enough to perform satisfactory
decontamination work and output.
In terms of dose reduction, we tried to raise their sense of accomplishment by measuring the dose inreal time after decontamination was done, and letting workers know how much the dose had been
reduced.
Regarding work output, we worked to achieve quality and volume of output by having teams of thesame number of people doing similar work at the same time in several locations. We would announce
their output on a daily basis in an effort to create some competition.
In the future, I think that there will be fewer large-scale decontamination projects, but even in smallerscale decontamination work, we want to do our best for the reconstruction of the Hamadori District,using the techniques we developed and not forgetting what we worked so hard to learn.

176

Column“Challenges and solutions in decontamination work”
Mr. Hajime Fujishima, Kishimoto-Kensetsu (subcontracted by Obayashi Corporation)

It has been around six years since I came to Fukushima Prefecture on myassignment. In that time, we have engaged in decontamination demonstration projects
in Hirono Town and full decontamination work in Kawauchi Village and Tomioka
Town. But no one had previous experience in the work of decontamination, so
initially it was like trying to grasp a cloud as we searched for a way to proceed. Manyof the workers were inexperienced due to unemployment and career changes, so we
tried to avoid using technical language and were careful not to proceed with work
until they were able to understand what was required. When inspecting work sites, I tried to interact withas many workers as possible, and to make it a lively workplace where anyone could speak out about any
concerns. As a result, although workers differed in terms of where they came from, in age, and incompany affiliation, there was no conflict between workers and the workplaces were lively and cheerful,with good team spirit. We interviewed anyone who sought work here, being sure to check their healthstatus, medical history, and comprehension of decontamination work. Anyone found to be inappropriate
was not allowed in. By doing so, we were able to prevent inconsistencies in decontamination work andprevent serious accidents. Seeing nurseries and elementary schools returning to the calm that existed
before decontamination and seeing the children running around healthily, the workers were rewarded
with the feeling that their work had served the community. Going forward, I am committed to keep
focusing on the restoration work, and I feel a strong sense of determination and responsibility to continue
doing work that is safe and secure.。

177

Column“Thoughts on being engaged in decontamination work”
Mr. Sho Kawamura, Nikki Construction Co., Ltd. (subcontracted by Taisei Corporation)

I first started working on decontamination in the Kusano administrative district of
Iitate Village on the last day of June 2012, and already nearly six years have passed.
I think back to the victims of the Great East Japan Earthquake that struck on March
11, 2011. The villagers had to “evacuate from an evacuation,” and had no time tosettle comfortably back at home due to the huge problem of radioactive
contamination. It has pained me to think about that.
Decontamination work done in the absence of residents was something I had
never experienced before. When I went under the eaves or entered the gardens of a landowner’s homes,
or entered their forests and or farmland, I always had the mindset of acting with the care I would have if
this was my own home. I express my condolences from the bottom of my heart.
In the spring of 2013, our company started working on decontamination mainly on the residential land
Usuishi district where we had been assigned. It was a very challenging time for our company. Amongother things, with the magnitude of the task of hiring 400 workers, our company struggled to recruit
workers, and nearly half of the people we hired were inexperienced in the construction industry, making
me feel my limitations. We had to continually repeat explanations of things like safety measures,
technical terms, and work procedures. I always encouraged the workers to commit themselves todecontaminate carefully and conscientiously, as though this was their own town or field, forest or home.
Thinking back, due to small oversights, I am sure I inconvenienced the workers, with troubles inlodgings and accidents occurring on-site due to lack of checking.
However, as the years passed, once-inexperienced workers also learned and became capable of doing
what was required, and in 2017 more than 80 participating members were active as a powerful workforce. Of course, everyone including myself will not forget our original intentions, and we are working
with our commitment to learn every day.
We are collecting and packing grass, trees, branches and soil contaminated with an invisible
radioactive substance into large container bags and transporting them to Temporary Storage Sites. But
actually, I think there will be no complete solution during my lifetime. So I feel it is our duty to pass onto the next generation the knowledge and know-how that we gained in the past six years. In the hopesthat all of the more than 6,000 residents who lived in Iitate Village before the disaster can return as soon
as possible, I would like to continue doing the remaining work safely and quickly.

178

Column“Receiving incombustible and combustible materials at Temporary Storage Sites”
Mr. Tetsuo Ito, Ito Komuten Co., Ltd. (subcontracted by Maeda Corporation)

Contaminated materials removed from farmland, houses and forests as a result of
decontamination work are placed in large container bags and stored for a while at
Temporary Storage Sites. When storing them at Temporary Storage Sites, thecontainer bags of removed soil are stacked up and surrounded by shielding container
bags so as to shield the radioactive materials generated by decontamination work.
The height of the stacks is basically five layers for incombustibles and three layers
for combustibles.
The piles that still remain at Temporary Storage Sites in each municipality may appear to be nothing
special at first glance, but in practice, many refined techniques are necessary.
The first thing is that even though the container bags of removed soil transported in from each site are
uneven in shape and firmness while the shielding container bags are uniform. But the bags have to be
lined up horizontally and maintain their balance. The second thing is the speed at which removed soil
container bags must be handled. The receiving process will not work properly unless it is able to matchthe speed with which the bags arrive by transport.
At the beginning of the work, since the removed soil container bags brought in were being placed
somewhat randomly, it became increasingly difficult to maintain consistency in the height of theshielding container bags as the stacks at the Temporary Storage Sites grew higher. This dramaticallyreduced the speed of placing each container bag, so we decided to develop some countermeasures toaddress the situation.
As a first measure, we performed rough sorting of the container bags at the site of decontamination
work, based on the size and characteristics of the bags. The aim of the rough sorting was to make thecontainer bags somewhat more uniform.
As a second measure, we boosted the communication between the Temporary Storage Site teams andthe transportation teams. Prior to that, the only communication was to coordinate the timing of thehauling trucks, but we changed this to respond to the needs of the Temporary Storage Site teams in termsof the size and firmness of the bags.
As a result, it was possible to build the stacks more smoothly than at the beginning, which resulted inbetter work processes.
Over the past two years, through repeated trial and error, we have been able to establish standard work
methods for the stacking of the removed soil container bags, and this includes safety aspects.
Finally, in the context of ongoing efforts for the recovery from the earthquake disaster, our company
will do its part and make its utmost effort to assist with the post-earthquake reconstruction.

179

“Aiming for the peace of mind of village residents”

ColumnMr. Yoshiyuki Hagiwara, Murasaki kensetsu Co., Ltd. (subcontracted by OkumuraNishimatsu-Daiden Specified Construction Joint Venture Corporation)

Since 2012 I have been engaged in decontamination work in Katsurao Village, a typeof work that I had never experienced before. The work was often done on mountainslopes and in forests that is not accessible by heavy equipment, so workers often had tocarry the removed material by hand, and that limited the amount of work that could bedone in a day. When we thought about the amount of decontamination work to be done
it seemed like a daunting task, but we worked steadily, step by step, while ensuringsafety and looking for ways to make improvements.
We worked with a strong commitment to restore the village to a condition in which all the villagers
could live with peace of mind. Especially in our work of decontaminating farmland, I hope that in the
future the crops cultivated here will be safe for consumption. This is why we always carry a radiation
dosimeter to verify the decontamination effectiveness as we work withsteady determination. Initially, the decontamination workers tended
not to make a good impression and not be liked in the community, but
now they work with pride and a high sense of motivation.
We will continue to do safe and reliable work until the completionof the decontamination project of Katsurao Village, and am sincerely
hoping for smooth progress in the reconstruction of Fukushima
Prefecture.

180

Details of Decontamination Techniques (methods of use and conditions in Special
Decontamination Areas)
Details (methods of use and conditions) of the main decontamination techniques used in Special
Decontamination Areas are indicated below.
Ground / building surface etc.
① Removal of sediments
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

Workability
Development
technology
Devices Points
to remember

For leaves, moss, mud, etc., for residential areas, schools, parks, roofs of large
facilities, roofs, roof gutters, gutters and grounds, road paved, unpaved, bridge
pedestrians, and other sediments are removed.
· Remove sediments such as fallen leaves, moss, mud and so on with hands, scoops,
brushes or brushes with rubber gloves, rakes, etc., and pack them in a large
container bag.
· If the material of the roof is liable to be damaged, do not get on the roof directly,
remove sediments from a high place work vehicle etc. using mop etc.
· In consideration of diffusion of contamination by decontamination work, for example
in the case of residential area etc., decontaminate in the order of roof, gutter, yard, etc.
· For the place to decontaminate for the first time after the accident, work well bychecking whether it is a sediment at the time of the accident or whether the sediment isfallen leaves, etc., after the accident.
· Removal of sediment is particularly effective at high dose levels.
· Decontaminate from a place with a high dose level.
· Since mechanization is difficult, manual work is the main.
· In the work on the roof, measures against crash disasters (parents, safety belt) arenecessary.

② Wipe off
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

Wipe off on residential areas, schools, parks, roofs of large facilities, rooftops, exterior
walls / fences, rain gutters, road guardrails, pedestrian bridges, etc.
· Wipe carefully with waste cloths moistened with water etc. (including neutral
detergent and acetic acid), using each folded surface carefully until the condition
that the surface contamination density does not decrease substantially even byadditional implementation .
- To prevent redeposition of contamination, wipe off with a new surface every wipe.
· Remove deposits such as moss and mud which are difficult to remove, andcarefully remove brittle parts that do not hurt the material of the object, for areas
where dirt that can be confirmed visually and so on is severe.
· Exterior wall · fence and guardrail carefully remove in dry condition using a brush(including car wash brush, deck brush etc.) that does not hurt the material of theobject, instead of waste etc.
· Waste etc.
Brush (including car wash brush, deck brush)· To prevent recontamination, wipe in order from the high position to the low
position.
· If rust is present, rust itself is removed by wiping or the like.
· Application to rain gutters is effective in areas with high dose levels.
181

· It is difficult to obtain dose reduction effect for wiping roofs, etc., in low doseareas.
Workability
Development
technology
Devices · Points toremember· As radioactive cesium may be attached to the waste cloth etc. used for wiping, do
not touch it with direct hands directly.
· At high altitudes, scaffolding and aerial platform work are required.
· Wiping work is a lot of fragile objects, and work by manual work is the subject.
· In the work on the roof, measures against crash disasters (parents, safety belt) arenecessary.
· Regarding the roof, it is also effective to wash with a dry brush as to the roughsurface.

③ Brushing
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

Perform cleaning such as residential areas, schools, parks, roofs of large facilities,
pavement surfaces such as exterior walls, fences, yards and grounds, concrete, asphalt,road guardrails, pedestrian bridges and so on, using brushes and the like.
· Clean carefully until decompression density does not decrease as a result ofadditional implementation by deck brush or scrub brush.
· Apply water at 4 L/m2 before brushing, and after brushing rinse with about 4 L/m2
of water as well.
· Clean the drainage path of wash water beforehand so that smooth drainage can be
performed and recover waste water with a rainwater cell. The recovered
wastewater is transported to a wastewater treatment facility in or near the site.
· Deck brush, sewage, etc.
· Sprinkler car (tank capacity 3,800 L), water· Temporary installation etc. for wastewater collection· To prevent recontamination, perform brush cleaning in order from high position to
low position.
· When targeting the roof of the roof or roof tile, the rotating brush is not suitable
and is not used.
· It is applied to a narrowed part where high pressure water cleaning
cannot be applied, a fragile roof and the like.
· Concrete retaining wall etc. · It is effective for structures such as gardenstone· In the work on the roof, measures against crash disasters (parents, safety belt) arenecessary.

Pavement surface etc.
① High pressure water cleaning
Overview

How to implement
decontamination

For high-pressure water washing, such as residential areas, schools, parks, roofs oflarge facilities, roofs, roofs, roofs, pavement surfaces such as exterior walls, fences,rain gutters, yard and grounds, concrete, asphalt, road pavement surfaces, guardrails,
Clean with high pressure water machine.
· If sediments are present, remove them beforehand.
· In order to prevent the gutter from being broken, use a high-pressure washer, inprinciple, rinse with high pressure water of about 5 MPa or less, about 2 L/m2.
· Clean roof and rooftop with high pressure washer, in principle about 15 MPa, withhigh pressure water of about 20 L/m2.
· The pavement surface is cleaned with high pressure water of about 20 MPa and 20
L/m2 in principle, using a suction type high pressure washer.
· In order to obtain cleaning effect, bring the injection port close to the object to be
182Required
Equipment,
Machine, etc.

Prerequisites
Constraints
Application
conditions

cleaned (about 20 cm) and wash at an appropriate moving speed.
· Clean the drainage path of wash water beforehand so that smooth drainage can be
performed and recover waste water with a rainwater cell.
· The recovered wastewater is transported to the wastewater treatment facility insideor near the site.
· Sprinkler (tank capacity 3,800 L), water, water supply tank (1 m 3 made ofpolyethylene)· High pressure washer (Motor driven, output 18kw 3.7kw)· Suction type high pressure washer (discharge pressure 20.5 MPa, vacuum pump)· Roadside gutter cleaning vehicle (blower type, hopper capacity 3.1 m 3, air flowrate 20 m 3 / min)· Motor generator (rated capacity 17 / 20kvA, exhaust type (primary))· Temporary installation etc. for wastewater collection· Submersible motor pump for work (50 mm in diameter, 20 m in total)
Rotary suction remover (φ 300, φ 450)
· Track with crane (2 ton stacking, 2.9 t hanging)
Sewage filter (200 L), sewage tank (1 m 3 made of polyethylene)· Do not splash water around the periphery, inside from the edge, from the upstream
towards the downstream of the water gradient.
· Care with sheets etc. so that water does not splash around. Waterproof paint, washwith care not to break the waterproof sheet.
· Confirm beforehand that there is no possibility of breakage etc. of objects etc. byhigh pressure water washing.
· Be aware that there is a possibility of damaging property such as peeling of thesurface.
· In order to prevent scattering of soil, etc., due to water pressure, first wash at low
pressure, wash gradually by raising the pressure gradually while checking theflow of washing water and scattering situation.
· Clean the parts where many sediments are adhering, such as roof overlapping parts,
parts corroded with metals, roof drains around, etc.
· When targeting a pavement surface etc., a suction type high pressure washer isused, but in the case of other objects, the waste water is collected with a rainwater
vessel or the like.
· Pavement surface freezing, work is not possible during snow covering.
· There were cases in which the high pressure water washing of the roof was not
carried out when the roof was damaged when the roof of the general house waswashed with high pressure water.

183

Workability
Development
technology
Devices · Points toremember· It is not applicable to fragile roof, etc.
· It is incompatible with steep slope roof.
· In the work on the roof, measures to prevent crashes and accidents (parent routes,
safety belt) are necessary.
· In order to reduce labor saving and efficiency bymachine construction, we developed a vehicle
capable of efficiently and safely performing roaddecontamination by improving the vehicle torecover the function of drainage pavement. (Thesame applies to extra-high pressure water cleaning)
Credit: Kajima Corporation

Credit: Maeda Corporation② Ultra high pressure water cleaning
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.

Provision
conditions
Constraint
conditions
Application
conditions
Workability
Development

Scraping the surface using an ultra-high pressure water washer for pavement surfaces
such as schools, parks, large-scale facilities grounds, concrete, asphalt, road pavement
surfaces, etc.
· Use a super high pressure washer (cleaning water recovery type) of 150 MPa or
more to scrape off the pavement surface (about 5 mm).
· Collect scraps generated by a powerful suction vehicle.
· Recovered decontamination waste water is divided into scrap (sludge) and water byperforming coagulation sedimentation treatment and the like.
· Scoop, borax etc.
· Extra high pressure water washer (Maximum pressure 240 MPa (including strong
suction))· Roadside gutter cleaning vehicle (capacity 5.1 m 3)
· Motor generator (output 3 kVA, low noise type)· Air compressor (portable exhaust type (primary), 3.5 to 3.7 m 3 / min)· Sprinkler (tank capacity 3,800 L)· Pavement surface freezing, work is not possible during snow covering.
· If cutting in the vicinity of the curb is impossible with the ultra-high pressure water
washer, perform a handy type · end compatible type or high pressure water
washing.
· For types that are not of wash water recovery type, scatter curing is performed, andwashing water is collected by suction car etc. using roadside gutters etc.
· Measure the surface dose rate after decontamination after the road surface dries.
· The introduction of the technology which automatically performs waste watercollection, the work speed has greatly improved. It is particularly effective in a184technology
Devices · Points torememberwide range of decontamination.
· In wide area decontamination, it is necessary to decontaminate roads in order to use
roads for transportation of removed materials and so on.

③ BlastOverview
How to implement
decontamination

Required
Equipment,
Machine, etc.

Prerequisites
Constraints
Application
conditions

Workability
Development
technology
Devices · Points toremember

Scrap the surface using shot blasting machines, such as residential areas, schools,
parks, pavement surfaces of large facilities such as yards and grounds, concrete,asphalt, paved surfaces of roads, and the like.
· Shatter blasting machines to scratch the surface uniformly by knocking abrasive
material such as iron ball particles on the surface.
· Cut asphalt scraps etc. are collected by a dust collector connected to the blastingmachine and packed in a large container bag.
· Since dust is generated, curing and other measures are taken to prevent scatteringto the surroundings, and dust is recovered.
· Collect abrasive material remaining on the road with hand-pushed magnet car andcollect it.
· Shot Blasting Machine (Cleaning Width 700 mm, 1,000mm)· Motor generator (rated capacity 100/125 kvA,
125/150 kvA, exhaust type (primary))· Dust collector (For cleaning width 700 · 1,000
mm, wind speed 75 m)· Track with crane (4 t product, 2.9 t hanging / 8 t
product, 2.9 t hanging)· Track (4t product, 8t product)
Credit: Maeda Corporation.
· Apply on a relatively large area paved surfaces.
· Pavement surface freezing, work is not possible during snow covering.
· When rain or when the road surface is wet, it is difficult to collect work and cutting
material and stop working.
· Removal rate decreases in places with rut or cracks and pavement compared to flat
surface.
· If the road is uneven or the crack width is 5 mm or more, the same construction
method cannot be adopted.
· At the cutting edge, to eliminate unevenness, a lap of about 5 to 10 cm is necessary.
· Because the end of the pavement surface such as the building and adjacent to thestructure cannot be constructed 15 to 30 cm, decontaminate by high-pressure
water washing or the like.
· It is effective only with high-pressure water washing (including super highpressure)for high dose level areas where dose cannot be reduced.
· It is necessary to remove accumulated sediments such as side parts in advance.
· It is not applicable to places with many cracks.
· It is not applicable to wet parts.
· Construction property drops greatly in a narrow area where the pavement area isabout 10 m2 in a residential area.

185

④ Cleaning by road cleaning vehicle
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

Clean up with a road cleaning vehicle for pavement surfaces of roads.
· Clean with a road cleaning vehicle for preparation work or maintenance before
decontamination work.
· Collect the removed items in flexible container bags.
· Scoop, borax, brush, etc.
· Road surface cleaning vehicle (brush type, hopper capacity 3.1 m 3 four wheel
type)· Frozen road surface, it is impossible to work when snowing.
· When collecting the decontamination collected in a flexible container bag, curing
and other measures are carried out to prevent the dust from scattering.
· Preliminary decontamination of sediments of road shoes was carried out with aroad cleaning car.
· In wide area decontamination, it is necessary to decontaminate roads in order to
use roads for transportation of removed materials and so on.

Credit: Maeda Construction Co., Ltd

Unpaved surface etc.
① Weeding, lawn mowing
Overview

Weed and grass clippings using grass cutters etc. are carried out for unpaved surfaces
such as yard such as residential areas, grasses such as schools, parks, large-scale
facilities grounds, street trees of roads, etc.
How to implement · Before removal of sediments and top soil, weeds that interfere with work aredecontamination
weeded, weeded, and cut down by shawl mowers or human power.
· Package removed grass and turf in bag of large soil.
Required· Mower (shawl type, cutter diameter 255 mm)
Equipment,· Dump truck (loading mass 2 t product), truck (loading mass 4 t product, 2.9 t
Machine, etc.
hanging)
Prerequisites· It is not possible to work when the object is frozen or snowy.
Constraints
Application
conditions
Workability- The workability of the weeding work on the steeply sloping site is greatly reduced,
Development
and the economic efficiency is also lowered.
technology- In some cases steep sloping grounds are included, there are cases where it isDevices · Points toinevitable that it is a harvesting work using a safety belt or manual work, and work
rememberefficiency and opportunities to be implemented are limited.

186

② Deep cutting of turf
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

Deep cutting of turf with a sod cutter or a large lawn mower is targeted on unpaved
surfaces such as yard such as residential area, grass such as school, park, large groundfacility ground, lawn etc.
· After grass cutting and grinding, use the hand guided lawn mower (Sod cutter etc.)
to cut the lawn grass deep (about 3 cm thin recoverable stripping).
· When large-scale lawn mowers are put in, use heavy-duty lawn mowers to cut deep
(about 3 cm).
Leave the root mat layer.
· Package the removed turf in a large container bag.
· Cover the stepped part and cover soil (about 3 to 6 mm).
· Hand guided lawn mower (reaping width 55 ~ 65 cm)· Backhoe (crawler type, exhaust type (secondary), standard bucket volume pile 0.28
m 3 (flat pile 0.2 m 3))· Dump truck (loading mass 2 t product)· Clay material (grassy soil)· It is not possible to work when the object is frozen or snowy.
· Large lawn mowers are limited to flat working sites and loose sloping surfaces.
· The application of a large lawn mower is high in economic efficiency and work
feasibility, but application conditions such as a vast and flat terrain are limited.
· Cutting with a large lawn mower is efficient, but it is premised on application in aflat place.

③ Scraping the topsoil
Overview

Scrap off topsoil on unpaved surfaces such as yard such as residential area, soil suchas school, park, large-sized facility grounds, unpaved side of road, etc.
How to implement · Scrape out the topsoil uniformly (about 5 cm) by scooping, screeching, backhoe, etc.
decontaminationand pack it in a large container bag.
Required· Scoop, shade etc.
Equipment,· Backhoe (crawler type, exhaust type (secondary), mountain 0.45 m 3 (flat area 0.35
Machine, etc.
m 3), mountain 0.28 m 3 (flat area 0.20 m 3), mountain 0.13 m 3 (flat area 0.10 m 3))
Prerequisites· Confirm the scraping thickness in advance by consultation. At the work stage, we
Constraints
will promote reliable compliance with the scraped thickness and try to reduce theApplicationdose reliably.
conditions· To prevent differences in scraping thickness from being caused by workers,
standardize work content to workers before work.
Workability· Particularly through work is essential for work around houses. Human power is theDevelopment
main work for work, depending on the situation, small heavy machinery can betechnology
used but the workability is not high.
Devices · Points to · For decontamination around houses it is assumed that human power or mini
rememberbackhoe, etc., is applied.
· Since the lead-in wires (electricity, telephone, internet wiring, etc.) are hinderedaround the house, careful remedial measures such as alerting and protecting
measures must be thoroughly taken carefully.

187

④ Covering the land surface
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.

Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

We will perform leveling of the clay material for unpaved surfaces such as yard suchas residential area, soil such as school, park, large-sized facility ground etc., unpaved
side of road etc.
· When topsoil is removed, cover it with the same type of soil as before, by the scoop
etc. to the original thickness.
· Leveling the topsoil and leveling, restoring the topsoil before the scraping of the
topsoil, with the same compaction degree as before.
· Scoop etc.
· Backhoe (crawler type, exhaust type (secondary), mountain 0.28 m 3 (flat area 0.20
m 3))
· Vibration roller (discharge pair type (primary) combined type 3 to 4 t)
Vibration roller (hand guide type, 0.5 to 0.6 t, 0.8 to 1.1 t)· Dump truck (loading mass 2 t product)· Clay material· It may be difficult to secure the same kind of soil as before.

· Application of versatile backhoe, etc., is superior in terms of workability andeconomy.
· Clay material according to planting plant, etc., may be necessary in some cases.

⑤ Deep plowing
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

Drill the surface soil and lower soil for unpaved surfaces such as yard of houses etc.,
soil such as schools, parks, grounds such as large facilities etc., unpaved side of roads,
etc.
- Surface soil is peeled off homogeneously by about 10 cm with human power orbackhoe, and temporarily placed on vinyl sheet, etc.
· Remove the lower soil by about 20 cm, uniformly, and temporarily place it in a place
different from the surface soil.
· After leveling the surface soil with a scoop or backhoe, leveling the lower soil,
leveling it, restoring it to the same degree of compaction as before, up to the present
condition level.
· Scoop etc.
· Backhoe (crawler type, exhaust type (secondary), standard bucket capacity 0.28 m 3(flat area 0.2 m 3) mountain 0.45 m 3 (flat area 0.35 m 3))· Vibration roller (discharge pair type (primary) combined type 3 to 4 t)
· Compaction machine (tamper)· Because it is a work method that does not remove contaminated soil, there are cases
where it is not acceptable especially in residential areas.
· It is important to temporarily place soil so that the upper layer peeled soil does not
get mixed in the peeled soil of the lower layer (securing decontamination effect by
preventing recontamination).

188

⑥ Removal of topsoil such as roots of trees, drains, near eaves
Overview

Removal of topsoil for roads such as residential areas, schools, parks, yard of large
facilities, grounds of trees such as ground, drainage outlets, near eaves etc., forexample.
How to implement · Take scoops, rakes, etc. to scoop accumulated deciduous leaves and soil, and pack it
decontamination
in a large container bag.
Required· Shovel, rake, etc.
Equipment,
Machine, etc.
Prerequisites· Depending on the situation of rainfall flowing out, the work site may be a hot spot.
Constraints
It is necessary to consult with supervisory personnel beforehand and decide work
Application
flow etc. to be certified as a hot spot.
conditions
Workability· Particularly polite tasks are essential for work around houses. Human power is theDevelopment
main work for work, depending on the situation, small heavy machinery can betechnology
used but the workability is not high.
Devices · Points to · There are cases where it is possible to introduce large heavy machinery forrememberdrainage outlets and planting of large facilities, but consideration according to theapplication place is required.

⑦ Removal of gravel and crushed stone
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.

Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points torememberGravel and crushed stone are removed for unpaved surfaces such as yard such as
residential areas, gravel such as schools, parks, large-scale facilities grounds, crushedstones, unpaved surfaces of roads, etc.
· Gravel and crushed stone are homogeneously removed (about 5 cm) by bags, scoops,
backhoes, etc., and bagged in a large container bag.
· If the thickness of gravel, crushed stone in the current situation is less than 5 cm,
gravel, crushed stone and topsoil of about 5 cm in total are removed
homogeneously, including the soil underneath.
· Scoop etc.
· Backhoe (crawler type, exhaust pair (secondary), mountain 0.45 m 3 (flat area 0.35m 3), mountain 0.28 m 3 (flat area 0.20 m 3), mountain 0.13 m 3 (flat area 0.10 m 3))· Vibration roller (Combined type, mass 3.0 ~ 4.0 t)· From the viewpoint of work efficiency, it is desirable to implement heavy equipment(small backhoe etc.) as much as possible.
· From the viewpoint of work efficiency, it is desirable to implement heavy equipment(small backhoe etc.) as much as possible.
· It is necessary to adopt a stripping method considering the size and narrowness ofthe target site, and apply large backhoe and compact or mini backhoe, etc., to thetarget area.
· In many situations, lead-in wires (e.g., electricity, telephone, Internet wiring, etc.)
to houses etc. are obstructed, so work requiring attention and measures such asprotective measures is essential.
· When peeling off with heavy machinery, safety measures such as loudspeaker hornetc. that can attract attention to operators in case of emergency and placement ofobservers for the surrounding safety are important.

189

⑧ Cover of gravel, crushed stone
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

Cover gravel and crushed stone for unpaved surfaces such as yard such as residentialarea, gravel such as school, park and large facility grounds, crushed stone, unpaved
side of road, etc.
· When gravel or crushed stone is removed, cover the gravel and crushed stone withthe backhoe, etc., with the same type of gravel and crushed stone as before, cover
the same current condition height as before, at the same compaction degree as
before.
· Backhoe (crawler type, exhaust pair (secondary), piled high 0.45 m 3 (flat area 0.35m 3), piled high 0.28 m 3 (flat area 0.20 m 3), piled high 0.13 m 3 (flat area 0.10 m))· Vibration roller (Combined type, mass 3.0 ~ 4.0 t)· It may be difficult to secure the same type of stone as before.

· Since the scraping thickness and covering thickness are 50 mm and the standard
value is ± 10 mm, if the size of purchased crushed stone is 40 mm, it takes time tofinish with this accuracy.

190

Yard tree, planting① Branch removal from yard trees
Overview

We plant branches of yard trees, hedges, planting, street trees etc., for yard trees suchas residential areas such as yard trees, schools, parks, grounds for large facilities etc.,
street trees on roads, etc.
How to implement · Depending on the type of trees and the timing of branch removal, branches anddecontamination
pruners such as yard trees, hedges and planting are done by pruning machines andbranch cutting shears within a range that does not significantly affect the growth oftrees.
· Pack pruned branches and bags in large container bags. Those of a length not stuffed
in a large container bag are cut so that they can be packed.
Required· Revival
Equipment,· Aerial Working Vehicle (Truck Equipment Lift Boom Type Work Floor Height 9.7
Machine, etc.
m)
· Chainsaw (saw length 350 mm, displacement 34 cc)· Truck (with crane device) (loading mass 4 t product, 2.9 t hanging)
Prerequisites· Depending on the height of the trees, planting, street trees on the standing trees,
Constraints
branch removal is equivalent to pruning of coniferous trees.
Application
conditions
Workability· Depending on the species of trees, there is a possibility of branch removal andDevelopment
aptitude, so it is necessary for landscaping professionals to confirm.
technology· Since hedging is the purpose of hedge, if it cuts too much, it will not be able toDevices · Points todemonstrate its function. Do not pay attention to each one, pay branch within therememberrange that blindfold as a whole.
② Logging and harvesting of troubled trees
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

We will cut down yard trees and hedges, targeting planting such as yard trees inresidential areas etc., schools, parks, large facilities etc.
· Forest trees with a breast height of 6 cm or more are cut from the root using a
chainsaw or the like. Cut the root pot and cut it out.
· Put the removed items such as leaves, branches, stems, roots, etc., into the large
cotainer bag. Those of a length not stuffed in a large container bag are cut so thatthey can be packed.
· Chainsaw (saw length 350 mm, displacement 34 cc)- Logging is not carried out as a standard. It is carried out when it is indispensable tocarry out other decontamination work or when the dose can be effectively loweredby logging at high doses.
· It is necessary to confirm the trees to be harvested by having the persons concerned
witness and mark them.
· As the trunk diameter increases, the work efficiency drops dramatically.
· Applying preservatives, etc., according to tree species is required.
· Hedge follows the branch removal.

191

Others① Wiping, cleaning, scraping of playground equipment
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points torememberWipe, wash, and scrape for school, park, playground equipment of large facilities, etc.
· Wash the surface of playground equipment with brush or cloth. If necessary, useneutral detergent, acetic acid or the like.
· High pressure water washing is performed on the joint portion of the metal
playground equipment. Rust of metal playground equipment is scraped off withsandpaper, grinder, etc., then gently wipe off.
· Wooden playground equipment wipe or polish wood surface with waste, brush,
sandpaper, electric power tool.
· Wipe off with care such as waste moistened with water, etc., (including detergent
and acetic acid), use each folded surface and carefully polish until the surface
contamination density does not decrease much even by additional implementation
wipe it off.
· Brush, waste etc.
· High pressure water washing machine· Brushes, sandpaper, grinders, electric tools etc.
· If the surface is smooth with the painted playground equipment (steel bar, jungle
gym, etc.), wipe with a paper towel, etc., However, if there is irregularities on thesurface of school monuments etc., brushing is done in a dry state.
· When decontaminating playground equipment, etc., at school facilities, explain
beforehand that the paint on the surface may be peeled off by wiping or brushing
work, and discuss with school officials.
· Different workability is different depending on the type of playground equipment ·standard.
· Decontamination of playground equipment was carried out, but since infants andchildren use it, replacement is often done at the time of business restart. It is necessary
to confirm the intention of school officials, etc., in advance.
· In areas where rust is generated, the dose may not decrease unless rust is removed.

②Removal of bottom sediment such as roadside gutter of road
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

For the roadside gutters, etc., of the road, wash the sediment with high pressure waterand suction the sediment.
· Remove sediments such as fallen leaves, mud, etc., which are easy to remove using
a scoop or the like in advance.
· If concrete joints in the roadside gutters are deep, remove sediments of the joints
using a spatula or the like.
· Use a drainage cleaning car or the like at about 14 MPa, wash with about 20 L/m2 ofwater, and collect wastewater.
· Package the removed sediment in a large container bag. The recovered wastewater
is transported to a wastewater treatment facility in or near the site.
· Scoops, brooms etc.
· Roadside gutter cleaning vehicle (blower type hopper capacity 10.3 m 3, 3.1 m 3, airflow rate 40 m 3 / min)
· Drain pipe cleaning car (tank capacity 2 m 3, pressure 14 MPa)
· To prevent scattering, if the building is adjacent, do curing.
· In case of washing the roadside gutter with lid with high pressure water, in order toclean the bottom surface, the side surface and the top portion (bottom surface of thelid) in the roadside gutter, using an injection tool in which the high pressure water
diffuses in the circumferential direction, Take the method to move.
· In the roadside gutter with the lid, when soil flowing from the mountain or
192

Workability
Development
technology
Devices · Points torememberembankments accumulates more in the roadside gutter and injection equipment does
not enter and high pressure water cleaning cannot be performed, remove the lid of
the section once and remove manually I do.
· When removing manually operated roadside gutters with no lids, the road is flat, so
use a unicycle when transporting the removed sediments to the piling location.
· When washing roadside gutters or the like with high pressure water, check thedrainage route in advance, lay down small container bags in the downstream
roadside gutters, provide weirs, and collect collected drainage with roadside gutter
cleaning cars. As a precautionary measure, if necessary, spread a small container
bag containing zeolite on the downstream side of the work site.
· In washing using injection equipment, drainage amount increases because bottom
quality is recovered by flowing to the downstream. Therefore, the waste water
treatment amount also increases.
· For sludge containing a lot of water, fill it in a small container bag and drain it,then refill it into a large container bag. Also, a pressurized dehydrator was used toshorten working time.
· A side stream decontamination system has been developed and applied to remove
sediments in a water channel at once with application of mud removal technology
such as a lidding with high pressure water and suction recovery. Even for awaterway without a lid, it was possible to effectively decontaminate a waterway
without attaching a top cover and scattering washing water around the waterway.
強力吸引車
強力吸引車
High Power
Vacuum Car

高圧洗浄車
高圧洗浄車
High
Pressure Washing Car

Top board
Cover
天板カバー
Upstream
上流側
上流側

Downstream
下流側

ChannelWashing Equipment
開渠用洗浄機
水路用洗浄機Spill Prevention
Sand Bag
流出防止土嚢流出防止土のう天板カバー
Topboard Cover

Credit: Shimizu Corporation· In the method of sucking and collecting contaminated soil together with washingwater, a solid-liquid separation step (step of separating contaminated soil andwashing water) and a water treatment step are required.
· Because work clothes are contaminated due to handling of bottom sediments andrebounding of high pressure washing water, in high dose section, we have useddisposable Tyvek suits, etc.
·Bottom quality of roadside gutters is often higher than surrounding decontamination.
It is necessary to pay sufficient attention to diffusion of contamination by highpressure water, etc. Also, it is necessary to pay attention to workers’ radiation
exposure measures.

193

③Removal of grass, deciduous leaves, sediments on embankments
Overview
How to implement
decontamination

Removal of shrubs, weeds, etc., grasses, fallen leaves, and sediments are carried out
for the embankments.
· Prior to the removal of sediments, weeds that interfere with work are weeded, andcut down by shawl type mower or human power.
· Remove deposits such as deciduous leaves, moss, mud and the like with a rake etc.,
and pack in a large container bag.

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions· Mower (shawl type cutter diameter 255 mm)· Truck (with crane device) (loading mass 4 t product, 2.9 t hanging)· Removal amount (thickness) is determined after test work.
· When decontaminating the cut surface, check the condition of the lath net and makeit.
· In the case of slope developed by earth cutting, taking into consideration thecircumstances of the surroundings and the like, the work range will be about 20 mfrom the living area.
· The vegetation engineer selects an appropriate work method by Road Earthmoving
Surface Planning and Slope Stabilization Engineering Guidelines (June 2009 (Japan
Road Association)).

Workability
Development
technology
Devices · Points toremember· When the inclination angle of the slope becomes steep, the work efficiency
decreases.
· When collecting decontamination on a declaration, pay attention to the method oftransportation of large decomposed bags of decontamination (especiallytransportation method above the surface of the legs)· Decontamination of declining surfaces from living areas cannot be expected,
decontamination of rising surfaces is effective.
· The effect of decontamination may be low only by removing deposits.

Grass, support tree, etc.
① Paddy field, field manure weed
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development

Paddy fields and field grasses will be subjected to weed control by manpower.
· Use a shawl-riding grass mower to weed rice fields and fields.
· Shawl-type grass mower (Shoulder hanging cutter diameter: 255mm)· Weeding in a narrow place and a embankments where mechanical weeding cannot
be introduced.
· Pay attention to the working time under high dose.
· Wear protective clothing, masks, gloves and safety boots.
· Injuries by cutting the foot due to jumping of the blade.
· When using mowers, safety education (practical training) is required.

194

technology
Devices · Points toremember② Mechanical weeding of paddies and fields
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.

Weeding grasses by machine in paddy field and field.
· Weed rice fields, fields, and pastures using agricultural tractors.
· Agricultural tractor (110ps, wheel type)· Offset transmitter (working width 200cm)· Agricultural tractor (110ps, wheel type) + Offset transmitter (working width
200cm)· Some rollers are used.

Example of using an off-set sender

Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

Example of using rollers
Credit: Kajima Corporation.
· The area to be decontaminated to a certain extent (more than 1,000m2), and the area
where there is no danger such as falling down of the machine.
· Stop work in muddy conditions after rainfall.
· Wear protective clothing, masks, gloves and safety boots.
· Agricultural machinery can be used.

③ Collection of cut grass
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points torememberCollect cut grass from paddies and fields.
· Collect cut grass using a grass collector, a grass mower/packer, etc.
· Grass collector (hand guided type, 120cm)· Mowing packing machine (hand guided type, φ500 × 700)
· Mowed grass packing machine (Hand guide type, φ500 × 700)
· Contiguous areas to be decontaminated, over a certain size (more than 1,000 m2) andwhere there is no tipping danger for the equipment.
· For outdoor work wear protective clothing, masks, gloves and safety boots.
• Stop work if conditions are muddy after rainfall.
· In some cases, roll bailers and other machines that separate the tasks of grass
cutting and collecting are used.

195

④ Weeding of meadow
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.

Weed grasses for pasture.
· Weed grass pasture by tracer.
· The grass removed will be collected and packed in a roll-barrel, and thentransported and collected after it has been made into a roll-bar.
· Spray herbicide with a boom sprayer.
· Agricultural tractor (passenger · wheel type four wheel drive 52 to 59 grade (70 to80ps))· Flail mower (direct installation) (width 1.5 m)· Roll baler (width 1.0 m, height 1.0 m)· Rake (width 3.6 m)· Boom sprayer (600 L, width 12.3 m)· Truck (loading weight 4.0 to 4.5 t)· Herbicide

Rake

Boom Sprayer

Flail mower

Credit: Taisei Corporation
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember· Carry out in the area subject to decontamination to a certain extent (1,000 m2 ormore) and in places where there is no danger such as falling of the machine.
· Wear safety glasses, masks, gloves and safety boots for outdoor work.
· Agricultural machinery can be diverted.
· Roll balers can do grass cutting and packing at the same time.
· Store every soil in large container bags.

196

⑤ Brush cut (shrub)
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

Workability
Development
technology
Devices · Points torememberGrass shrubs are cut for grassland and shrub bushes.
· Weeds, shrubs, etc., are cut by chain saw, etc., transported and bundled, bagged inlarge container bags.
· For items that cannot be transported / accumulated as it is, shredded shrubs etc.,
cannot be bagged, cut and bagged in a large container bag.
· Mowers (Chainsaw saw length 600 mm (80 cc))
· Mowing machine (shawl type cutter diameter 255 mm, 1.3 kW class)· Because the shape of the grassland and turf is various, first check the size of the local
flatland etc., select the place to pack in the large container bags, transportationroute, loading place, etc., Particularly, in places where bagging or temporary
placement is carried out, safety of operation is secured by selecting a flat place.
· Establish safe work paths and haul roads prior to mowing and paying work to ensure
safety of feet.
· In a dense area of shrubs, basically use a chain saw to do brush cutter.
· In the coarse area of shrubs, basically a shoulder-type grass cutter is used to cut
brush. In a mowing machine, when there is a thick shrub which is difficult to cut
and cut, use a chain saw.
- Cut the shrub shoots to the size that can cut off the branches and carry it, transport
it, accumulate.
· When cut down high-height bamboo, since bamboo that was cut is hindered andsometimes workability gets bad, carry it out in a long state every time you cut andcut it.
· When packing bags, because branches, etc., may damage large container bags, sothat the cut ends are not sharp, and prevent damage to large container bags.
· When filling bags, removable goods do not fit well and the large container bag will
collapse, so by fixing the large container bag to the exclusive stand, it is easier toinsert and advance bag filling work with less mold breakage .
· There is a limit to the filling performance with bagging by human power, so
economic efficiency / workability is inferior.
· If packing is bad, it may be compressed by load when stacked in a Temporary Storage
Site, and the temporary storage stability may be impaired. These combustibles may
rot and cause generation of flammable gas and settling / deformation.
· From the viewpoint of volume reduction, it was made into chips by a self-propelledwood crusher and the like to enhance packing properties.
· Compressing and shaping carved trees and branches and leaves etc. into a roll shapeand packing by wrapping Further volume reduction and corruption control
technology Eco roll is introduced to reduce volume of combustible materials ·suppress corruption, We have made effective use of the site and secured soundness
during the storage period.
· When exiting the workplace, confirm that it is not contaminated with screening
exceeding 1,300 cpm, which is stricter than the contamination limit (13,000 cpm).

197

⑥ Logging of bamboos
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points torememberCut the whole bamboos to paddy field and soil of field.
· Cut the bamboos by chain saw, cut brush and slice off.
· Load removed materials (leaves, branches, trunks) into the unladed haulers, transport
and accumulate them.
· Digging up the rhizome of bamboo and do root soil separation.
· Load sifted substances (roots) in a non-land transporter, transport and accumulate.
· Fill back, flatten the ground, and roll back the excavated area.
· Backhoe (with skeleton bucket) Piled high 0.45 m 3· Crawler dump truck 1 t· Chainsaw· Wear safety glasses, masks, gloves, safety boots· Treating thoroughly bamboo grown after the earthquake.
· Collect branches, trunks and roots.
· Be careful not to bounce the chain saw during ball cutting.
· In case of lower mowing, pay attention to bouncing of the mower.

Backhoe (with skeleton bucket)

Credit: Taisei Corporation

Soil① Land conditioning
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

Paddy and field soil, subject to inelastic adjustment.
· Use vibrating rollers, etc., to correct the unevenness of the topsoil.
Vibration roller (boarding type combined roller 3 t exhaust type primary)
In super wet fields such as self-jetted paddy fields, thecombined rollers sink and cannot move, so work is
impossible.
· Beforehand whether the combined roller can run orcheck the trouble capability.
· As rainfall and puddle parts will rebuild the surface partof the cultivated soil, in principle work is not done.

Credit: Obayashi Corporation

Workability
Development
technology
Devices · Points toremember· If heavy machinery, etc., cannot enter, create an approach route. Therefore,
economic efficiency and workability of the sloping land deteriorates from the flatground.

198

② Surface hardening material spray
Overview
How toimplement
decontaminati
on

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices·
Pointstoremember

Paddy fields and field soils are sprayed with surface hardening material.
· Spray the solution mixed with solidified material using a seed spray machine andconfirm that the surface soil has solidified sufficiently.
· The amount of solidifying material in the solution is 15 t / ha, the solidified thickness
is 2 to 3 cm, and the curing period is assumed to be 7 days (continuous no
precipitation days).
· Confirm that radioactive substances are not detected beforehand in water used forsolution.
· Seed spraying machine (vehicle type (seed only) 1.0 m 3)
· Air compressor (25ps, 0.7 MPa, 2.5 m 3 / min)· Truck with crane equipment (4 ton stacking, 2.9 t hanging)· Sprinkler (tank capacity 3,800 L)· Surface hardening material (neutral solidification material)· In the winter season, work is impossible because the solidified material does not
solidify.
· Because it requires a curing period, it is restricted by weather condition.
- Spraying to places where water is pooled is impossible.
· When scraping over the topsoil of 25,000 Bq / kg or more, it is done as measures toprevent high dose of dust scattering.
· If heavy machinery, etc., cannot enter, create an approach route. Therefore,
economic efficiency and workability of the sloping land deteriorates from the flatground.

199

③ Scraping the topsoil
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

Workability
Development
technology
Devices · Points toremember

Scrap off topsoil on paddy field, field, pasture soil.
· Using backhoe, belt conveyor built-in type scraper, tow type scraper, etc., scrape off
the topsoil. (About 5 cm).
· Backhoe (exhaust type (primary), crawler type stacking 0.45 m 3 (flat stacking 0.35
m 3))
· Light oil· It is impossible to work in super wet fields such as self-jetting paddy fields.
· Determining the scraping thickness according to the dose level (depth distributionof radioactivity concentration).
· When rice straw and shrub rhizomes (willow, etc.) are under the surface layer,
remove them with heavy equipment etc.
· If necessary, add fertilizer, organic material and soil improvement material. Peel off
the mixed soil and strip it homogeneously with backhoe, etc., according to thethickness.
· The work method which showed its effect by a method different from the standard
includes a skimmer method and a turf stripper. Together with agricultural machine
manufacturers, these agricultural machinery manufacturers have been working on
development and improvement.
· Skimmer method is a technique to efficiently
scrape and recover agricultural surface layers
using compact and lightweight dedicatedequipment with automatic topography
response system by electronic control(thickness control sensor). There is a scraperon the machine front part, a belt conveyor
Skimmer method
for scraping the top soil is provided byhorizontal rotation of the special resinboard, and it is possible to load the earth andsand scraped off in a parallel or tracking
transport car directly.
· Work speed of skimmer method is about 3
times that of backhoe, economic efficiency ishigher than backhoe. Since the dose
Turf stripper
reduction rate of the skimmer method is
Credit: Shimizu Corporation
higher than the backhoe higher than thebackhoe, the accuracy is higher than that of the backhoe.
· If heavy machinery, etc., cannot enter, create an approach route. Therefore,
economic efficiency and workability of the sloping land deteriorates from the flatground.
· For this reason, if the cutting thickness can be made thinner and the work range iswide, if the dry soil is large, the amount of scraped off soil is greatly reduced, andthe work cost is reduced, but there are restrictions on the flatness of the surface
There is a need for joint use with another work method for the range where work
is impossible. Also, the number of machines themselves is small.
· Because there are overhead lines in farm roads and agricultural land besideagricultural land, clearly indicate the position of the overhead line with flags andflags, etc. When passing, prevent overhead line damage accident by deploying
traffic controller.

200

④ Reverse cultivation / Deep Plowing
Overview
How to implement
decontamination

Reverse cultivation or deep cultivation is carried out for paddy field, field, pasturesoil.
· Overturning is carried out once at a plowing depth of 30
cm or 45 cm with a plowed tractor.
· Using a rotary tiller for deep plowing, cultivate and stirwith a target of about 30 cm in plowing depth and plow
the field deeply.
Rotary tiller
Credit: Obayashi Corporation

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

Workability
Development
technology
Devices · Points toremember· Tractor for agriculture (passenger · wheel type four wheel drive 52 to 59 kW class(70 to 80ps), 22 kw class (30ps))· On agricultural land where work soil was agitated by plowing after the accident,
carry out overturning or deep plowing.
· Fruit trees, tea ceremonies, etc. If deep plowing is carried out where perennial
crops are cultivated, there is a risk of damaging the roots.
· If the worker layer is gravely, gravel appears in the working layer due to deep
plowing, so measures such as graveling are required.
· If necessary, measure the groundwater level and take great care to deeply cultivateit.
· When the temperature is low and the topsoil is frozen, the function of the small
tractor may not be sufficient.
· For land not cultivated after the accident, deep tillage is applied when the soil
concentration is lower than 5,000 Bq / kg.
· It is important to check the depth distribution of soil radioactivity concentrationand the depth of the tiller and to determine the inversion depth.
· Unlike scraping, contaminated soil does not occur, so it is superior to scraping off
the top soil and covering soil in economic efficiency and work fee .
· If heavy machinery, etc., cannot enter, create an approach route. Therefore,
economic efficiency and workability of the sloping land deteriorates from the flatground.
· Determine the optimum depth of work by confirming the depth of the cultivation
layer and foundation gravel layer.
· Because there is a risk of breaking the tiller, it is necessary for the tiller to belocated at a depth of 30 cm or more.
· It is necessary to have the ground tolerance that the backhoe can operate.

⑤ Excavation
Overview
How to implement
decontamination

Required
Equipment,

We will carry in the soil of paddy fields and fields etc., delivery of covering soil,
spread and compact.
· After scraping off the soil, use the heavy machine to do the land clay, flatten thelevel, level up, recover to the height of the present condition.
· The quality of the covering soil is decided in consultation with the supervisorypersonnel.
· Submit the soil covering material to the supervisory personnel prior to use so thatthe soil test table and radioactive materials concentration measurement result are
obtained before use.
· Scoop etc.
· Backhoe (crawler type, exhaust type (secondary) piled high 0.28 m 3 (flat stacking
201

Machine, etc.

Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

0.20 m 3))· Vibration roller (discharge pair type (primary) combined type 3 to 4 t)
· Vibration roller (discharge versus hand guide type 0.5 to 0.6 t)· Dump truck (loading mass 2 t product), earth and sand
· For agricultural land that was not plowed after the accident and agricultural land inwhich the working layer was stirred by plowing after the accident, the former, where
the topsoil remains unchanged, even if the radioactive cesium concentration is thesame, has a high value as the air dose rate which should be noted.
· It is necessary to analyze and diagnose soil after decontamination, and then makenecessary amount of soil covering and so on.
· If heavy machinery, etc., cannot enter, create an approach route. Therefore,
economic efficiency and workability of the sloping land deteriorates from the flatground.

⑥ Ground recovery
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

Ground will be restored by soil conditioner or zeolite spraying for paddy field, field,
pasture ground soil.
· Sprinkle the soil conditioner while pulling the spraying device with the tractor.
· Tillage was reported to the Governor of Fukushima Prefecture as a special fertilizer
under the provisions of the Fertilizer Control Act (Act No. 127 of 1954), which
comprehensively improves the physicochemical and biological properties of thesoil and produces soil it has a function to enhance the power.
· Submit soil remediation material to supervisory personnel prior to use to obtainconsent.
· There is also a method of spraying zeolite instead of soil conditioner.
· Construction tractor (usually 9t), agricultural tractor (crawler type, 40ps)· Spraying equipment (tow type capacity 800 L working width 3 m class), (working
width 1.8 m class)· Soil conditioners (calcium carbonate, potassium silicate), zeolite· After soil analysis and diagnosis after decontamination, it is necessary to consider
the necessary amount of soil conditioner or zeolite.
· If heavy machinery, etc., cannot enter, create an approach route. Therefore,
economic efficiency and workability of the sloping land deteriorates from the flatground.
· The MOE decides and instructs the spray menu of the restoration material.
· Soil conditioners promote the growth of weeds, and there is also material delivery.

⑦ Double plowing
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application

Plowing is carried out twice on paddy field, field, pasture soil.
· Till and agitate using rotary etc. after spraying ground recovery material, etc.
Tilling and stirring are standardized twice.
· Agricultural tractor (passenger wheel type 4 wheel drive 22kw class (30ps))· Work is impossible in super wetlands such as self-jetting paddy fields where there isa possibility that the tractor may sink and not run.
· Check the trafficability whether the wheel type tractor can run.
202

conditions
Workability
Development
technology
Devices · Points toremember· If heavy machinery, etc., cannot enter, create an approach route. Therefore, economic
efficiency and workability of the sloping land deteriorates from the flat ground.
· Determine the optimum depth of work by confirming the depth of the cultivation
layer and foundation gravel layer.

Waterways① Removal of bottom sediment (raising earth and sand)Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions

Workability
Development
technology
Devices · Points torememberRemove sediment and so on (raising earth and sand) for waterway of agricultural land.
· Remove deposits such as fallen leaves, moss, mud and the like that are easy toremove using a scoop or the like.
· Scoop etc.
· Removal of waterways on agricultural land is almost done by manual labor becauseof narrow working environment.
· In the work, put the removed sediment in the pouch at once in the vicinity, andcarry out small transportation by human power. As a container suitable forcarrying, use a bag with a hand belt.
· When water is flowing through the waterway, remove the upstream anddownstream sides of the work range, use a submersible pump that can be installedby human-powered conveyance, remove work without running water.
· In the catchment basin and the like of a waterway where radioactive materials areaccumulated and hot spot is high concentration, it is necessary to pay attention to
cumulative exposure management of workers and to shorten the operation time asmuch as possible.
· The waterway has a long working range, so that raising the earth and sand in man
powering work is inferior in economic efficiency and constructability.
- In the lidded waterway, sediment containing radioactive materials is deposited not
only on the bottom of the waterway but also on the lid hook, and it is necessary to
remove them together.
- It is necessary to pay attention not to leave earth and sand.

② Removal of bottom sediment (bag stuffing)
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development

Remove sediment (bagging), etc., for waterway of agricultural land.
· Package the removed bottom sediment in bags of large container bag by manpower.
· Large container bags
· Removal materials do not fit well during bag filling work, so large container bags
may collapse in some cases. Therefore, by fixing the large container bag to the
exclusive stand, it is easy to introduce, advance the bag filling work with less moldbreakage.
· Because the water content of the bottom sediment is large, add inner bags to large
container bags or use flexible waterproof containers to prevent leakage of sewage.
· The length of the work is long, the bagging in manual labor is carried, bags packed
in small pieces with small container bags are packed in large container bags, so it

203technology
Devices · Points torememberis inferior in economic efficiency and constructability.
· In the side trench decontamination system which removes sediment in the water
channel at once by applying high-pressure water by applying mud removal
technology such as lidding, suction collects sediment accumulating in thewaterway together with high-pressure water washing water into the vacuum car.
· In the method of sucking and collecting contaminated soil together with washingwater, a solid-liquid separation step (step of separating contaminated soil andwashing water) and a water treatment step are required.

Others① Bag filling (standard transport method)
Overview
How to implement
decontamination
Required
Equipment,
Machine, etc.

Put paddy soil for paddy field, field, pasture soil.
· Collect elimination soils using backhoes and so on and pack them in large containerbags.
· Backhoe (exhaust versus (primary)· Crawler type stacking capacity 0.45 m 3 (flat stacking 0.35 m 3))· Large container bags

Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember· A jig such as a production frame for packing in a large container bag is necessary.
· Align the height of large container bags after packing.
· In a wide range of agricultural land decontamination, the plowed removed soils areaccumulated, and the large container bag filling work is carried out in a state ofbeing assembled to some extent. Human power work such as attachment of bags
to large container bag production frames and binding of bag mouth after filling is
also necessary, which is inferior to economic efficiency.
· A method of stuffing the removed soil into large container bags behind the machinewith a screw conveyor type scraper with a special bucket with a hammer knife has
also been developed.
· Skimmer method and Turf stripper method are also effective in packing bags.

204

① Removal of organic residue and residue
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.

Evergreen coniferous forests, deciduous broad-leaved forests, etc., are subjected toremoval of organic residue and accumulated organic residue.
· Gather rags, fallen branches etc. with rakes etc., about 5 cm from the surface (about
10 cm in unmanaged areas), carry, collect and bag in a large container bag.
· After removal of organic residue, at the place where accumulated organic residue isleft, accumulate them again with rakes, etc., and pack it in a large container bag.
· Remove to the extent that the mineral soil layer is not exposed.
· Glove, rake, dustpan,· Blue sheet, carrying bag.

Credit: Taisei Corporation
Prerequisites
Constraints
Application
conditions

Workability
Development
technology
Devices · Points toremember· If it is difficult to secure work safety with general safety measures due to the steep
slope, strengthen safety measures at the time of work according to the situation of
the land.
· In areas where safety measures cannot be taken due to steep slopes or the like,decontamination work was carried out by negotiating with the supervisor,
separately setting the scope of work (e.g., upper slope, decontamination up to 2 mfrom the slope bottom, etc.).
· When exposing the roots of the trees, it becomes a cause of deterioration of the forest
function, so in removing it, consult with the forest managers and supervisorypersonnel sufficiently so as not to expose the roots of the trees, decide the applicable
scope.
· In sharp mountainous areas, it is necessary to transport with a small manpower up to
the slope and the efficiency drops, so the workability and economic efficiency may
be inferior.
· Considering the small transportation of the removed materials, carrying small
sandbags to workers and carrying out collection work.
· There were many illegal dumps in the forest, sorting of decontamination andremaining waste was occasionally added.

205

② Undergrowth · shrub brush
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points torememberEvergreen coniferous forests, deciduous broad-leaved forests, etc., are subject to
cutting and removal of undergrowth and shrubs.
· Mow cuttings of undergrowth, shrubs, etc., are carried out by shawl-type grass
mowers, etc., When there is a cutting branch, a falling branch etc., collect them on
the edge of the forest and pack them in a large container bag.
· For items that cannot be packed in a large container bag, cut it so that it can be
stuffed, or bind it with a cord or the like so that it becomes a coarse loaf of about
30 cm in diameter with a length of 2 m or less and accumulate in the edge of theforest.
· Shawl type grass cutter, rake, rake, hand knitting, carrying bag, chain saw.
· It is carried out in order to improve the prospect of the root of forest trees.

· Removal products that have been transported to the slope for a small amount may
コンテナへの除去物の積み込み
be subjected to a volume reduction process (compression by a suction bag or
crushing of branch trees) on 積み込み
the spot, but efficiency can be improved by reducing
the volume collectively. By using the arm roll car and the container, it is possible
to transport the removed material without waste.

Aggregate volume reduction location

Loading of remover to container

Arm roll car· Since it is a narrow range of work between forest
trees, it is necessary to clearly indicate the work range(especially grass cutting work) with tape or the like,and prevent other workers from entering the workarea, to prevent accidents caused by grass cutters.
Credit: Taisei Corporation

206

大③ Pruning of conifers, collecting of cutting branches
Overview
How to implement
decontamination

Required
Equipment,
Machine, etc.
Prerequisites
Constraints
Application
conditions
Workability
Development
technology
Devices · Points toremember

For evergreen coniferous forests, pruning of coniferous forests and collection of
branches are carried out.
· For evergreen coniferous forests (Cryptomeria japonica, Cypress and other cedar) of
Ⅲ grade or higher class, branches up to about 4 m above the ground are cut off bysaws, etc., for standing trees in the range of about 5 m (1 to 2 rows) from the edgeof the forest.
· Make sure that the length of the crown does not fall below the original half.
· For similar types of standing trees covering buildings with branches and leaves
considerably, they are cut off with a saw or the like.
· Cut off branches within 2 m in length. Bundle them with cords, etc., so that they
become fascine of about 30 cm in diameter, pack them in large container bags, andcarry them to the edge of the forest.
· For those that cannot be packed in large container bags, cut them so that they can bepacked and bag them.
· Saw, hatchet, etc., high branch cutters, blue sheet· Electric chain saw for high branch, carrying bag.
· It may be applied to the wind protection forest around the residential area.

· Removal substances that have been transported to the slope for a small amount may
be subjected to volume reduction treatment (crushing of branch trees) on the spot,
but efficiency can be improved by reducing the volume by concentration. By using
the arm roll car and the container, it is possible to transport the removed material
without waste. (See ② Undergrowth and shrub brush)· From the viewpoint of safety work, use a high branch scissors, high branch electricchain saw, without using a ladder, up to 4 m above the ground.
· Try to prevent injuries to be used only by experienced people.

207

The metrics for full decontamination in the Special Decontamination Areas are indicated in the table,
including work period, total area, and monthly area. The difference is large for each municipality due todifferences in the number of workers assigned, etc., and the monthly amounts range from 10 to 200 caseson residential land (1 to 30 ha), 11 to 50 ha of farmland , 2 to 10 ha of roads, and 1 to 30 ha of forests.
The period of time and the number of workers required for decontamination depended on many factors,
such as the size and area of the roof and land, the roof and wall material, the size and condition of the yard
(presence of yard trees, etc.), the availability of the lift trucks, the need to install temporary scaffolding,the need to replace gravel, the need to decontaminate nearby forests, and the transport of removed soil,etc., to Temporary Storage Sites, etc. As a result, it is difficult to generalize, but typically the work perhousehold would require 5 to 10 workers and about two weeks. Also, according to Provisional
Quantification Standards for Decontamination Work, for example, to remove sediments on a roof (otherthan concrete) in residential area, the standard per 1,300 m2 was 0.50 supervisors, and 3.20 regulardecontamination workers.

Table 4-4 Full decontamination metrics (work period, total area, monthly area)
Residential land

Farmland

Roads

Forests

Properties

Area
(ha)

Work
period(months)

Properties

Area
(ha)

Work
period(months)

Properties

Area
(ha)

Work
period(months)

140

23

6

140

6

29

6

190

6

2,600

420

13

830

16

170

16

470

16

160

17

10

130

10

38

16

200

16

180

37

16

170

16

31

16

160

16

460

150

31

570

31

95

31

660

31

360

99

37

600

39

71

34

510

39

Futaba Town

97

9.0

10

100

8

8.4

5

6.2

8

Iitate Village

2,000

440

43

2,100

49

330

43

1,500

49

Tomioka
Town

6,000

590

35

750

40

170

39

510

38

Namie Town

5,600

600

36

1,400

35

210

35

390

37

Minamisoma
City

4,500

690

33

1,700

38

270

36

1,300

37

Municipality
TamuraCity
NarahaTown
KawachiVillage
Okuma
Town
Katsurao
Village
Kawamata
Town

208

＜Quantity per month＞
Residential land
(properties/month)

Residential land
(ha/month)

Agricultural land(ha/ month)Roads(ha/month)

Forests(ha/month)

City

23

4

23

5

32

Naraha Town

200

32

52

11

29

Kawauchi Village

16

2

13

2

13

Okuma Town

11

2

11

2

10

Katsurao Village

15

5

18

3

21

Kawamata Town

10

3

15

2

13

Futaba Town

10

1

13

2

1

Iitate Village

47

10

43

8

31

Tomioka Town

171

17

19

4

13

Namie Town

156

17

40

6

11

Minamisoma City

136

21

45

8

35

Average

72

10

26

5

19

Municipality
TamuraNote: Work period is the period during which work on the corresponding land category was performed ineach municipality, including waiting periods during the work
The area per month is calculated from the total number of cases or area and the total work period, and may
differ significantly depending on actual work conditions, etc.

209

Decontamination Effects in Each Targeted Area
A document entitled “On the effect of the decontamination method in the decontamination projects
implemented by the national government and local governments so far” (January 2013, Decontamination
Team, Ministry of the Environment) brought together and organized information on the results of initial
decontamination work (mainly during 2011) conducted by the national and local governments mainly inareas with relatively high radiation levels in Fukushima Prefecture, and summarized information on theextent to which the amount of radioactive substances could be reduced by decontamination.
Among the data on decontamination work implemented initially, the report focused on data on thevicinity of residential areas, such as buildings and other structures and roads. (Fields and forests are
not subject to analyze because of a lack of data for analysis.)
Since the aim was to compile information on the effects of each decontamination method, it was
decided to use the ratio of reduction of surface contamination density by each decontamination method
as the decontamination effect analyzed.
In order to reduce variations due to factors other than the target of decontamination, the target ofanalysis was data for surface contamination density before decontamination of 2,000 cpm or more.

Rain gutters and roadside gutters, etc.
① Rain gutters· The reduction rate of the surface contamination density is about 60 to 80% by wiping after removal of
sediments, and it is about 40 to 80% by washing with high pressure water after removal of sediments.
Wiping after removal of sediments has a higher reduction rate than high pressure water washing.
· Because a significant amount of radioactive substances accumulates in sediments in rain gutters, it isimportant to note that removing those sediments is an effective means of implementing
decontamination.
② Rainwater drains· The reduction rate of the surface contamination density is about 60 to 90% by washing with highpressure water after removal of sediments.
· Sediment removal is being done, and its effectiveness is believed to be significant.
· In terms of data interpretation, it is important to note that the reduction rate will be lower due to highconcentrations of radioactive substances penetrating seams and cracks due with initial rainfall.
· In terms of decontamination implementation, it is important to note that if the rainwater drain isdamaged, care should be taken because of the possibility that the surrounding soil may becontaminated.
③ Roadside gutters· The reduction rate of the surface contamination density is 70 to 90% with removal of sediment, and it
is about 60 to 90% with high pressure water washing after removal of sediment.

210

· In terms of decontamination implementation it is important to note that since a large amount ofradioactive substances were accumulated in sediments in roadside gutters, it was sufficiently effective
only to remove sediments, and that where roadside gutters are damaged, the surrounding soil could becontaminated and require extra care.
Roofs, etc.
· The reduction rate of the surface contamination density in the case of roofs is about 0 to 20% (*) by
wiping, about 20 to 60% by washing, and about 40 to 80% by washing with high pressure water. (*For the wiping off of the roof of a private house conducted in the autumn of 2012, a reduction rate ofabout 20 to 50% was achieved by improving the wiping method.)· In case of a rooftop, the reduction rate is about 60 to 90% in high pressure water washing. It isconsidered that the shape of the rooftop is not very complexed, so the effect by high pressure water
washing is significant.
· In the case of a veranda, etc., the reduction rate is about 20 to 50% by high pressure water washing.
However, the dataset is small. It is about 60 to 90% by washing with high pressure water after removalof sediments.
· Below are some points to keep in mind for data interpretation.
- Variations will arise depending on the material and shape of the surface of the roof.
- In high pressure water washing, the results varies how much contaminated water remains.
- For roof cleaning and wiping, even for data with high surface contamination density, small reduction
rates can be observed in some cases. These cases are believed to be affected by factors such as rustand materials, such as cement roof tiles, unglazed clay roof tiles, and coated iron plates.
· The following are points to keep in mind when implementing decontamination.
- When decontaminating work using water, it is important to take measures to prevent the scatteringof washing water.
- Where rust is present, the benefits of washing with high pressure water may be low, so it is necessary
to remove the actual rust by wiping or other means.
- In the case of high-pressure water washing, it is necessary to be careful because property may bedamaged such as by peeling of surfaces.
Exterior walls① Concrete· The reduction rate of the surface contamination density is about 10 to 30% by wiping and about 20 to
80% by washing with high pressure water. However, the dataset for wiping is small.
· Radioactive materials may have already been washed away to some extent due to rain, as there wasmuch data showing low surface contamination density (less than 2,000 cpm) and the adhesion ofradioactive substances was small.
· In case of high-pressure water washing, it is necessary to be careful because property may be damaged
such as peeling of walls.

211

② Metal, windows, doors, shutters, etc.
· For metal, windows, doors, shutters, etc., of exterior walls, the datasets are small for all methods.
· In the case of metal, the reduction rate is 40 to 70% for washing and about 40 to 90% for washing withhigh-pressure water.
· In the case of windows, doors, shutters, etc., the reduction rate is 70 to 80% by wiping, 20 to 70% by
washing and 50 to 90% by high-pressure water washing.
· There is a possibility that radioactive materials were already washed away to some extent due to rain,
as there was much data showing low surface contamination density (less than 2,000 cpm) or theadhesion of radioactive substances was small.
③ Tile sidings· The reduction rate of the surface contamination density is about 60 to 70% by high-pressure water
washing. However, dataset is small.
· Tile siding high-pressure water washing has a higher reduction rate compared with high-pressure water
washing of concrete walls.
· There is a possibility that radioactive materials were already washed away to some extent due to rain,
as there was much data showing low surface contamination density (less than 2,000 cpm) or theadhesion of radioactive substances was small.
Yards, etc., site
① Dirt and grass areas· The reduction rate of the surface contamination density is about 0 to 60% by mowing, 40 to 80% by
topsoil removal, and about 70 to 100% by soil replacement.
· Soil replacement is carried out when the surface contamination density is relatively high.
· Below are some points to keep in mind for data interpretation.
- For topsoil removal in yards, there is a possibility that the reliability of decontamination work may
be lowered due to the presence of vegetation and the fact that yards may be uneven compared withsports grounds.
- For mowing, there is a possibility that the effectiveness of decontamination may vary due tovariations over time in the conditions of adhesion of radioactive materials to the grass itself, and may
be affected by the growing conditions of the grass.
- Mowing reduces the shielding effect of grass on beta rays and may reduce the reduction rate.
② Grass· The reduction rate of the surface contamination density is 70 to 90% in the case of grass stripping, andas high as about 90% for replacement (stones laid after grass removal).
· From the viewpoint of limiting the amount of removed soil generated and restoring the grass, in termsof decontamination implementation this is important to note that it is also necessary to consider
removal by “deep pruning,” which has been confirmed to have a certain effect in reducing the radiation
dose.
212

Paved surfaces such as parking lots
① Paved asphalt surfaces· The reduction rate of the surface contamination density is about 50 to 70% for washing, 30 to 70% for
high-pressure water washing, and about 70 to 90% for scraping.
· In high-pressure water washing, variations in reduction rate are large regardless of the surface
contamination density.
· In terms of decontamination implementation with high-pressure water washing, it is important to notethat there may be greater variations in the reduction rate if the decontamination area is large, such asa parking lot, due to variations in effectiveness depending on the operation method at each point(nozzle height above ground, working time per unit of area, etc.) and the surface conditions (water
permeability and drainage, etc.).
· Below are some points to keep in mind for data interpretation.
- For decontamination work using water, measures are needed to prevent the scattering and spread ofwashing water.
- If cracks or other such features are present, caution is necessary because of the possibility ofpenetration into the damaged portion.
② Paved concrete surfaces· The reduction rate for the surface contamination density is about 40 to 70% for high-pressure water
washing and about 60 to 90% for scraping.
For scraping, differences could appear in the reduction rate depending on the work method.
· In terms of decontamination implementation with high-pressure water washing, it is important to notethat there may be greater variations in the reduction rate if the decontamination area is large, such asa parking lot, due to variations in effectiveness depending on the operation method at each point(nozzle height above ground, working time per unit of area, etc.) and the surface conditions (water
permeability and drainage, etc.).
· Below are some points to keep in mind for implementing decontamination.
- Concrete is less uneven and the decontamination efficiency is relatively high, but contamination
tends to concentrate where moss is attached.
- For decontamination work using water, measures are needed to prevent the scattering and spread ofwashing water.
③ Interlocking· The reduction rate of the surface contamination density is about 50 to 80% by high pressure water
washing and about 40 to 70% by scraping.
· Below are some points to keep in mind for data interpretation..
- When scraping off, the reduction rate may be lowered by cutting scraps and radioactive materials
remaining in the gaps of the block.
- The reduction rate of interlocking scraping (shot blasting, concrete plane) is smaller than scraping of
paved asphalt surfaces or paved concrete surfaces. It is conceivable that cutting residue remained in
the interlocking gap.

213

Sports grounds, etc. (dirt surfaces)· The rate of reduction of the surface contamination density is relatively high at about 80 to 90% for theremoval of surface soil.
· It is believed that the lower level of unevenness of grounds enables a consistent reduction rate.
· In terms of decontamination implementation, it is important to note that it is necessary to check the depthof contamination from the surface layer in advance, and to set the optimum thickness of stripping.

· With most of the data being for washing, the reduction rate of the surface contamination density is about
0 to 50%. Most of that data is for drainage pavement functional recovering vehicles and the variation in
the reduction rate is large.
· The reduction rate of high pressure water washing is about 10 to 50%. However, the dataset is small.
· The reduction rate of scraping is about 10 to 70%. (*Improvement of the reduction rate is currently being
attempted by improving the recovery of cutting waste)
For washing, high-pressure water washing and scraping, in many cases the reduction rate is lower thanfor paved asphalt surfaces such as parking lots of buildings and other structures.
· Below are some points to keep in mind for data interpretation.
- When the decontamination range is large like a road, the high pressure water washing may varydepending on the operation method of the location (the ground height of the nozzle, working time
per area, etc.), variation in the reduction rate may become large due to the conditions of the surface(water permeability and drainage).
- In the case of using drainage pavement functional recovery vehicles with low water pressure andcirculating wash water, the reduction rate tends to be lower. In addition, the road washing andrecovery of wastewater is lower on road surfaces that are worn or are distorted by earthquakes orother factors.
· In terms of decontamination implementation, it is important to note that for decontamination work using
water, measures are needed to prevent the scattering and spread of washing water.

214

Part

Rain
gutterRoadside
gutterTable 4-5 Decontamination effect for each decontamination target
Average
Decontamination reduction 25% - 50% Details
Remarks
method75% valuerate
After deposit
gutters mainly in
67％
59－74－ Rainremovalprivate houses.
［n=212］
84％
Wiping off
Rain gutter
After deposit
Rain gutters mainly inremoval56％
40－68－ private houses. Partly,
High-pressure［n=131］
81％
combined with wiping.
water washing
Rain gutters in public
After deposit
Rainwater
67％
59－74－
facilities and private
removaldrains［n=212］84％
houses. Clean with
Wiping off
brushing as well.
Sediment
removalAfter deposit
removalHigh-pressure
water washing56％［n=131］40－68－
81％

67％［n=212］59－74－
84％

Wiping off

15％［n=
56］

2－9－
22％

Washing40％［n=235］16－45－
64％

High-pressure
water washing

55％［n=
76］

37－64－
81％

Rooftops

High-pressure
water washing

75％［n=
87］

63－78－
90％

Verandas,etc.

High-pressure
water washing

41％［n=
10］24－46－
53％

Wiping off

22％
［n=6］

10－19－
33％

High-pressure
water washing47％［n=19］

19－45－
76％

Washing51％［n=5］37－65－
69％

High-pressure
water washing

43％
［n=9］

44－83－
92％

Wiping off

74％
［n=8］

65－69－
84％

Washing46％［n=6］24－62－
65％

High-pressure
water washing

64％
［n=7］

53－70－
85％

High-pressure
water washing

61％
［n=4］

58－71－
74％

Roadside
gutterRoofs, etc.

Roof etc.
House,
facility,etc.

Concrete

exterior
wall

Metal
(tinplate,titanium,iron plate,etc.)

Window ·door·
shutter etc.

Tile siding
board

215

Only remove earth andsand.
Rain gutters mainly inpublic facilities. Clean
with brushing as well.

Mainly roof of privatehouse. Wiping with cloth,etc., Partly wiping with apaper towel.
Mainly roof of privatehouse. Deck brush wash.
Some, wire brushes andhand polisher.
Public facilities, privatehouses, factory roofs.
There are many
combinations withbrushing.
Roof of public facilities.
There are many
combinations withbrushing.
Veranda etc in public
facilities, etc., Partly,
combined with brushing
and wiping.
public facility.
There are many public
facilities, some privatehouses. Some use brushing
and wiping together.
Private house. Brushcleaning.
Factory, private house,school. Partly, wiping isused in combination.
There are many privatehouses and public
facilities.
Private house. Brushcleaning. Partly, wiping isused in combination.
The private house ismostly. Partly, brushing isused in combination.
Private house. There aremany combinations with

Part

Details

Averagereductionrate

25% - 50% 75% value

19％［n=144］-3－29－
55％

58％［n=232］42－68－
81％

73％［n=23］

65－79－
95％

72％［n=32］

72－80－
86％

86％［n=15］

85－87－
88％

52％［n=60］

47－59－
65％

46％［n=329］30－50－
67％

78％［n=20］

70－82－
87％52％［n=73］

35－56－
68％

73％［n=63］

62－81－
90％62％［n=45］

50－69－
76％

Topsoil54％［n=11］
85％［n=271］38－57－
65％
83－88－
93％

Washing20％［n=369］2－28－
49％

High-pressure
water washing

28％［n=
12］

13－24－
54％

Scraping

31％［n=125］7－39－
72％

Decontamination
methodMowingTopsoil removal

Earth/
GrasslandYard,etc., site

Replacement

Grass stripping
lawn

Replacement
WashingPavedasphalt
surfaces

High-pressure
water washing
Scraping

Parking
lot etc.
Pavement
surface

High-pressure
water washing
Paved
concretesurfaces

Interlocking

Scraping

High-pressure
water washing
Scraping

Ground
etc.

Road

soil

Paved
asphalt
surfaces

216

Remarksbrushing.
Public facilities,
warehouses, premises ofprivate houses.
Public facilities, factories,
parks, premises of privatehouses. Top soil removalof 3 to 5 cm or more
(before being covered).
Public facilities, premisesof private houses. Only
data with a relatively highsurface contamination
density. The backfill
material is gravel, crushedstone, soil.
Public facilities only.
Public facilities only.
Laying the crushed stone
after removing the lawn.
Mainly public facilities
site. Road cleaning truck.
Partly, metal brushsweeper, watering car +sweeper.
Mainly public facilities
site. There are many
combinations withbrushing.
Mainly public facilities
site. Shot blast.
Public facilities,
warehouses, premises ofprivate houses. There aremany combinations withbrushing.
Private house premises.
Shot blasting, vacuum
blasting, dust collecting
sander, grinding machine.
Premises of public
facilities and privatehouses.
Public facilities site. Shot
blasting, concrete sander.
Parks and schoolyards(before being lodged).
Mainly dense paving
section. Partly drainable
pavement. Drainage
pavement function
recovery car (mostly
washing water pressure
about 5 MPa). Some,
sweepers + watering cars,
metal brush sweeper.
Used in conjunction withsand discharging andbrushing.
Mainly dense paving
section. Shot blast.

Supplemental Decontamination

Supplemental decontamination was carried out at about 10,000 homes so far based on the results ofsupplemental monitoring, etc. Embankments, rain puddles, roadside gutters and other water spots werethe main target or this work, and the reduction effect was confirmed at approximately 50%.

Slope, Slope end
31％

Others29％

Undergrowth9％Water path
(gutter,drains)15％

Rain gutter, Rain
drains 15％

Others : concrete surface, asphalt surface, bare field
Analyzed Data( about 10,000 houses decontamination :about 1,000 houses were partially decontamination, about
9,000 houses were hot spot decontamination)

Figure 4-25 Supplemental decontamination locations

49％
Reduction
47％
Reduction

51％
47％
46％
Reduction
Reduction
Reduction

Rain
Water
Planting Others
gutters
Paths
Rain(gutter,waterdrains)drainsFigure 4-26 Dose reduction effect by supplemental decontamination (air dose rate 1 m above

Slopesground)Source: MOE, documents from “The 18th Investigative Committee on Remediation” (December 27, 2017).

217

4.4. Temporary Storage Sites
Securing Temporary Storage Sites

In promoting decontamination, it was essential to have places to temporarily store the removed soil, etc.,
arising from decontamination. To secure Temporary Storage Sites it was necessary to have theunderstanding of landowners and local residents, but since it was not initially possible to offer adequate,
residents voiced safety concerns such as the possibility of higher air dose rates near Temporary Storage
Sites, and the possibility that removed soils, etc., accumulated there might leak and spread. There werealso worries that the temporary storage period might be extended and the sites end up being used as disposalsites, and concerns that the removed soil, etc., from other areas might end up stored here.
In terms of securing Temporary Storage Sites, it was necessary to have sufficient area for placing theremoved soil, collected and to have access roads. In cases where the area could not be secured enough in
one Temporary Storage Site, multiple sites should be secured, and where the land was not flat, levelling
work was sometimes required.
Also, with regard to the necessary area, as the amount of removed soil, etc., would vary depending on
the decontamination method used, it was difficult to accurately predict the amount of soil to be removed.
Temporary Storage Sites were gradually added as the decontamination work progressed, but in some cases
the progress of work was affected when temporary storage sites were not ready.
In Intensive Contamination Survey Areas, it was necessary to secure Temporary Storage Sites but thisbecame very difficult to do while residents lived in the area and much of the land was in use, such as
agricultural land. If a Temporary Storage Site could not be secured, it was decided to use on-site storage.
In case of on-site storage in residential yards, if the period of storage was prolonged, in some cases it wasnecessary to relocate the removed soil, etc., in the event of expansion or renovation work on buildings, orsale of the property, etc.

In addition to carefully explaining the necessity of Temporary Storage Sites, MOE sought local
understanding to secure Temporary Storage Sites, in cooperation with administrative district managers,
community group chairpersons and others. Efforts were made to find realistic solutions with the local
communities, and candidate sites were selected by administrative district unit.
In addition, MOE explained Temporary Storage Site designs as well as shielding soil and management
methods, tried to resolve and relieve anxiety about their safety.
Temporary Storage Sites have lower air dose rates than the surrounding area because decontaminationand leveling are done when preparing the sites, and increases in air doses are prevented by installing shieldsoil. There was greater understanding of their safety thanks to these measures, plus the measuring of air
dose rates at the site boundaries, sharing of information with the local community, conducting site tours,
and by having residents themselves measuring and confirming air dose rates. Some municipalities also
made efforts to help residents feel safer by creating systems with the residents themselves monitoring thesites.
218

Also, understanding about Temporary Storage Sites was advanced thanks to some areas where thedecontamination work started, sites were secured and decontamination work advanced quickly, and there
were almost no concerns about the safety and contamination.
When it was difficult to set up a Temporary Storage Site, MOE was flexible in response to local
circumstances, for example, using on-site storage rather than making it an absolute requirement to have a
Temporary Storage. Particularly in areas outside of Fukushima Prefecture and urban areas in Fukushima
Prefecture, it was difficult to secure large Temporary Storage Sites, even though it was necessary to startdecontamination promptly. In such cases, many local governments carried out decontamination using onsite storage in residential yards and public parks, etc. by carefully explaining the safety and plans for
subsequent removal, etc., and asking for understanding.
Also, in order to reduce the amount of soil removed, etc., to be delivered to Temporary Storage Sites,
the decontamination waste generated was subjected to volume reduction such as shredding, crushing,compression and incineration as much as possible so as to reduce the volume.

Temporary Storage Sites are basically secured by lease contracts with landowners. There are many
contract periods of three years, but also one year contracts and also contracts that last until removal. If
extension of a contract is necessary, this is done based in consultation with landowners.

Flow of Storage at temporary storage sites ~ Transport ~ Original form reclamation ~ Restoration"Extension of storage period"
Transport (to Interim
Temporary Storage Sites<Initially> Export in three years *Continuation of storage

Storage Facility)

Original form reclamation

Restoration<Current status> Storage extension is required according to the process of transport to the interim
storage facility.
Process of transportation would be influenced by land acquisition, maintenancesituation, and transport plan, etc.

Continuation of leasehold
October 2011, Basic concepts on Interim Storage Facility “ Effort to start in service of Interim Storage Facility within three years in prospectfrom the start of accept soils from temporary storage sites.

Figure 4-27 Flow from storage to land restoration at Temporary Storage Sites and prolongation ofstorage period219

Column“Securing Temporary Storage Sites” Fukushima Regional Environmental OfficeTemporary Storage Sites had to be secured before starting decontamination which was a precondition
for obtaining consent and starting decontamination. It was important from the viewpoint of work,
management, and transportation of removed soil, etc., to have Temporary Storage Sites located on flat
land, with at least a certain amount of land area, and with good access. On the other hand, when securingTemporary Storage Sites, it was necessary to first obtain consent from the local residents in theneighborhood as well as consent from the landowner of the land at the Temporary Storage Site.
Regarding the location of Temporary Storage Sites, the original intention was to efficiently transportmaterial to Interim Storage Facility , and it was the policy to concentrate Temporary Storage Sites withinmunicipalities, but in many local governments, in the process of seeking cooperative relationship withlocal residents, the number of cases of Temporary Storage Sites in each administrative district increased.
For securing Temporary Storage Sites, the approach was not to just search for a suitable place on themap. Staff members of the Fukushima Office for Environmental Restoration (present: Fukushima
Regional Environmental Office) also went to locations in person to find suitable sites for temporarystorage and discussed matters with landowners and others. Some municipalities tried to set up Temporary
Storage Sites in forests, but it was difficult to secure land that was flat and sufficient in size, so the policy
was to coordinate with landowners to set up Temporary Storage Sites temporarily on farmland in eachadministrative district.
At briefing sessions, the residents were angry and anxious and it was not an atmosphere conducive to
explaining, but we continued to hold briefing sessions a number of times.
There was anxiety about leasing the paddy fields that had been handed down for generations, to be
used as Temporary Storage Sites, and a variety of other anxieties and concerns about their safety andpossible extensions.
These concerns were understandable, so personnel from the Fukushima Office for Environmental
Restoration explained each matter carefully. Initially, as there were no Temporary Storage Sites, it wasdifficult to imagine what they would be like. Therefore, we created a model of the Temporary Storage
Site, and used it to make clear explanations to land landowners and others. In addition, about concerns
about the spread of radioactive materials, we used pamphlets to explain that there was no risk ofradioactive materials leaking out, and explained that we would conduct monitoring which helped people
understand. Furthermore, in coordination with landowners, we were greatly helped by the cooperationof municipal officials and administrative district managers. Through these efforts we made progress inhaving people understand securing Temporary Storage Sites.
We will strive to promptly return the land to landowners by carefully managing the Temporary Storage
Site currently being leased, transporting the removed soils away, and restoring the sites to their original
condition.

・Source: “Decontamination Information Plaza Exhibit Lending Catalog (Model)”220

Establishing Temporary Storage Sites

Facility requirements and management requirements of Temporary Storage Site for rapid
decontamination are described in the Decontamination Guidelines section “Fourth Edition: Guidelines on
Storage of Removed Soil.”① Storing combustible materials
If removed leaves, fallen branches, logged trees and leaves or other combustibles are left in a pile, gas
will be generated due to decomposition and potentially cause a fire, so the material should be covered witha breathable water resistant sheet, etc., and degassing pipes and temperature sensors installed (Special
Decontamination Areas). Also, the storage condition of the waste should be checked regularly, and if whitesmoke or water vapor, etc., is confirmed, the internal temperature should be measured and managed
appropriately.
② Storing incombustible materials such as soil
Since incombustible materials such as removed soil will not generate gas even if stored, they can becovered and stored with an impermeable sheet that does not pass water.

Figure 4-28 Basic design of Temporary Storage Sites for above-ground storage of combustible
materials removed by decontamination

Figure 4-29 Basic design of Temporary Storage Sites for above-ground storage of incombustible
materials removed by decontamination

Source: MOE “Decontamination Information Site”

221

③ Ensuring safety
At Temporary Storage Sites, a fence or the like should be installed after sufficiently securing the distancefrom residential areas to prevent persons from accidentally approaching the sites.
To prevent scattering and runoff, and to prevent the infiltration of rainwater, etc., and the pollution ofgroundwater, etc., the removed soil, etc., is placed in flexible containers or large container bags, placed ona water-impermeable layer (waterproof sheets or other impermeable sheets), and covered with waterproof
sheets.
Radiation from flexible containers and large container bags is shielded by surrounding them withshielding container bags containing uncontaminated mountain sand, etc., to reduce the radiation dose at
the site boundary to the same level as the surrounding area. Soil with a thickness of 30 cm can reduce theradiation dose by 98%. Shielding soil at Temporary Storage Sites in Special Decontamination Areas uses
non-polluted soil at 400 Bq/kg or less, procured by purchasing soil or obtaining from nearby soil collection
sites. Also, the policy is to reuse the soil after the stored materials have been removed.
For organic materials such as plants and the like, in order to limit any temperature increase fromfermentation to a certain level, the size of each storage pile is kept small and the surface area per unit ofvolume is kept large, in order to boost heat dissipation. However, in the event of a temperature rise above
a certain limit, it is important to be prepared with access routes for heavy equipment, etc., and with fire
extinguishing equipment.

222

<Function and structure required for Temporary Storage Sites>
Temporary Storage Sites for removed soil, etc., are expected to provide the functions of “prevention of
scattering of removed soils,” “prevention of infiltration of rainwater, etc.,” “prevention of discharge ofradioactive material,” and “shielding of radiation, and limiting of additional radiation doses.” Therefore,
they are constituted the structure of equipment and materials to satisfy these functions.
① Prevention of scattering of removed soil, etc.
Removed soil, etc., is placed in bags that can have their openings closed or containers that can beclosed with a lid (highly weather resistant large container bags, flexible containers, etc.) before being
delivered to Temporary Storage Sites.
Containers delivered to Temporary Storage Sites are covered with soil or other materials to preventthe scattering of removed soil, etc.
② Prevention of infiltration of rainwater, etc.
Containers delivered to Temporary Storage Sites are covered with impermeable sheets such as
waterproof sheets so as to prevent rain from falling on them to the extent possible (or use containers
with a waterproof function).
③ Prevention of discharge of radioactive material
To prevent contamination of soil, surface water, and groundwater with leachate from removed soil,etc., the containers are placed on top of an impermeable sheet, etc., placed on the bottom surface (oruse a containers with a waterproof function).
④ Shielding and isolation of radiation
Radiation is shielded by covering the removed soil, etc., with shielding container bags, etc.
Fencing, etc., is installed around the Temporary Storage Site to ensure that people do not get in,thereby ensuring isolation.

2231) The outer circumferential road secures a passage width of 4 m of the heavy machinery, except for the installationsite of fences and surface water drainage grooves.(Securing 4 m distance for radiation protection)2)The storage place should not exceed 9 m on the short side and the length of the long side should be adjusted
according to the actual situation.
3)If there is work on a large crane, secure 8 m as a work space.
4)The passage width of the work vehicle is set to 3 m excluding the installation location of the monitoring hole of thewater collection facility.
Leaching water collection equipment (1-2m3)
Signboard
Firefighting equipment
Surface water collection drain
Temperature monitoring sensor

Approach path / work road

Approach path / work road

Approach path / work road

Approach path / work road

Approach path / work road

Outer fence
Surface water drain

Data collection equipment
Radiator tube (Gas vent pipe)
Groundwater monitoring tube
(Installation site is selected considering
topographical gradient etc.)
Work road*Rainwater elimination, washingprevention measures implemented

Figure 4-30 Example of Temporary Storage Site layout (location for combustible materials)
Explanation

Evaluation of radiation impacts from Temporary Storage Sites

It is also clear from evaluation by calculation that the impacts of radiation from removed soil, etc.,
stored at Temporary Storage Sites in Fukushima Prefecture were sufficiently reduced by taking measures
such as shielding by soil and ensuring the necessary isolation distance.
Preliminary condition of provisional place
VerticalSize
20m×width
20m×height 2 m
Radioactive cesium
10,000 Bq/kg
concentration inremoved soil
Storage method
Ground type
Shielding material
soil
Condition forSide shielding 1 mshieldingand upper
shielding 30 cm
Evaluation results of impacts of radiation from Temporary Storage Sites based on differences in shielding
and isolation distanceSource: Fukushima Prefectural Centre for Environmental Creation
224

Temporary Storage Site (Katsurao Village)

Temporary Storage Site (Namie Town)

Management facility (Naraha Town)

Temporary Storage Site under construction(Iitate Village)

Figure 4-31 Scenes at Temporary Storage Sites

225

Column“Design concepts for Temporary Storage Sites”
Mr. Kazuto Endo, National Institute for Environmental Studies

Decontamination is being implemented as a basic approach for “removing,” “isolating,”and “shielding” radioactive substances. A Temporary Storage Site is a place wherecontaminated materials that have been removed from the living environment are packed
into flexible containers, etc., and brought to Temporary Storage Sites away from the living
environment, to be stored there for a period of time until being processed in the future. Ifthey cannot be isolated from the living environment, measures are taken to block theradiation with shielding soil, etc., to ensure there is no impact on the living environment.
Contaminated materials include removed soil and decontamination waste. The former
is treated as incombustible, and the latter as combustible. In the case of incombustible
material, the stacking height at Temporary Storage Sites is set at five layers to ensure thestability of the pile and prevent the collected material from re-scattering, and to preventthe flexible containers and the large container bags from being damaged by the load. In
the case of combustible materials, heat may be generated by the decomposition of organic
substances, so the stacking heights are set at two or three layers from the perspective ofpreventing spontaneous ignition due to heat buildup.
At Temporary Storage Sites, a large amount of radioactive cesium will be present
because contaminated materials will be collected in one location. Therefore, from theperspective of preventing the leakage of radioactive cesium, an impermeable sheet is laidon the bottom. Since radioactive cesium is extremely low in elution due to its strong
adsorption to soil, it would not typically be necessary to use a water impermeable sheet,but that is being done as precaution. In addition, on the water impermeable sheet, acollection drain pipe is installed and connected to a water collection tank outside thestorage pile, so radioactive cesium can be monitored if it happens to leak out. The top of
the Temporary Storage Site is covered with an impermeable sheet, etc., so that excess rainwater does not intrude. Since incombustible materials do not generate heat, animpermeable sheet is used, but since combustible materials can generate heat, they arecovered with a breathable water resistant sheet (blocks water but allows gases to passthrough) to promote heat dissipation, and heat radiation pipes are installed to prevent
heat buildup.
Temporary Storage Sites are covered with the sheets after delivery of removed soil, etc.,
is completed, and monitored until the stored materials are carried out again. Efforts are
made to ensure the soundness of Temporary Storage Sites, including regular observation
to ensure the air dose rate has not risen suddenly, to notice if any leachate watercontaminated by radioactive cesium has entered the catchment tanks, and to notice
whether the protective sheets have moved or become damaged, etc.
Initially, the Temporary Storage Sites were presumed to be used for a storage period of
three years, but the expected three-year period for removal has now been exceeded, and226

maintaining them as temporary structures has become more difficult. To manage theoverall Temporary Storage Sites by water impermeability, as rainwater enters due todeformation of the pile and partial damage of impermeable sheets by birds and otheranimals, the management load increases because it is necessary to regularly pump waterout. Therefore, a new construction method to reduce the management load was adopted
by placing the removed soil, etc., collected from decontamination into waterproof flexible
containers or large container bags and then transporting them to Temporary Storage Sites,
eliminating the need for the impermeable sheets as well as collection and drainage pipes.
Since each storage container is water impermeable, it is no longer necessary to havewaterproofing or water collecting tanks at the bottom and not necessary to cover the upper
part with waterproof sheets. To prevent deterioration of the storage containers fromultraviolet light, the entire Temporary Storage Site is covered with a light-shielding mat.
In the absence of any previous experience or structure standards for the long-term
storage of not only incombustible but also combustible materials contaminated withradioactive cesium, various techniques other than those mentioned above have also been
introduced in the maintenance of the Temporary Storage Sites. We have arrived at today
after having made various improvements.

For Temporary Storage Sites in Special Decontamination Areas, MOE has prepared the “Standard
Construction Methods for Temporary Storage Sites in Special Decontamination Areas” in order to specify
the standards for building the sites, including basic concepts; preliminary studies, surveys and designs; site
leveling plans; ground preparation; foundation work; delivery and stacking of removed soil etc.; coverings;
end treatments; and associated facilities, etc. This document is loaned to contractors who do work relating
to the set-up of Temporary Storage Sites and, etc., and they do the work according to these Standard
Construction Methods.
The Standard Construction Methods have been revised and now are comprised of two editions, “Filling
Removed Soil, etc., into Containers that Are Not Water-Resistant or Waterproof” and “Filling Removed
Soil, etc., into Containers that Are Waterproof.” The revisions are based on the actual installation situationsat Temporary Storage Sites and issues that occur on site, and allow for options such as using a lightblocking sheet that is not waterproof as the covering sheet when containers filled with removed soil, etc.,
are water resistant or water proof.

The design of Temporary Storage Sites involves many factors that are site-specific. Initially, no detailed
design guidelines existed, and even after the newly-created design books were presented, it took time tobe recognized by supervisory personnel. Over time, these guidelines and reference diagrams werecompiled and improved.
The decisions for the location of each Temporary Storage Site were made under various constraints, and227

the work conditions were also unique in some cases. Most of the Temporary Storage Sites for direct
decontamination work under MOE were originally on agricultural land, so the ground loading strength was
weak, leading to concerns about ground subsidence, and the land became muddy when the rain fell. In the
future it is impossible to improve the ground to restore the original state to the landowners, secure the aisle
passages for heavy machineries and work yards with the ironing boards, arrange the removed soil, etc.,
delivered order from the back side of the Temporary Storage Site, It piled up and it was work to retreat tothe entrance side.
Also, since the sites to be decontaminated were in an area with layers of decomposed granite, there werecases in which decomposed granite layers were also scooped up in the preparation of the Temporary
Storage Sites, and it was difficult to prevent scouring in installing drainage gutters in such places.
Since there were overhead lines and the like at some of the Temporary Storage Sites, there were cases
in which it was necessary to modify the shape of the storage pile in order to ensure a minimum distance
between the boom and the overhead lines during crane operation.

In the Intensive Contamination Survey Areas, there are municipalities that decontaminate by on-sitestorage rather than setting up a Temporary Storage Sites, due to the need to quickly start decontamination
work. For on-site storage, the two methods are above-ground storage and underground storage.
For above-ground storage, a waterproof sheet is spread out and containers containing removed soil, etc.,
placed on top, and then a waterproof sheet is placed on top to prevent rainwater infiltration, and the edges
or the sheet are secured to prevent them from blowing in the wind. For underground storage, the on-sitestorage location is excavated, a waterproof sheet is spread out, the containers containing removed soil, etc.,
are placed, and then covered with soil.
According to the “Guidelines on Storage of Removed Soil,” in order to ensure safety, when storing 2 m
× 2 m × 1 m removed soil, etc., it should be covered with a covering soil layer at least 30 cm thick, or it
should be at least 1 m away from any building where persons live. If it is not possible to have this distanceof at least 1 meter, the response was to taking shielding measures.

228

① Above-ground storage

Embankment

at least 1m

Sandbags

Water Shielding layer② Underground storage

Embankment(at least 30cm)

at least 1m

Sandbags

Water Shielding layer

Figure 4-32 Examples of storage of removed soil
Source: MOE “Guidelines on Storage of Removed Soil”

229

In the decontamination, etc., work ordered by MOE in Special Decontamination Areas, storage
containers being used are mainly flexible containers of about 1 m 3 capacity (size: φ about 1.1 m × H about
1.1 m) and large container bags. Considering the characteristics and weight of the removed soil, etc., to be
stored, as well as the storage period and other factors, if the storage was to last over a certain period oftime (multiple years) or where the removed soil contained high levels of moisture, weather-resistant inner
bag were used, such as cross-shape flexible containers, running-type flexible containers, and heavy weather
resistant large container bags with inner bags, etc.
In the initial plans, since it was estimated that storage at the Temporary Storage Sites would be about
three years, products with weathering resistance of three years were often used for large container bags,
but even if storage is to continue for three years or more, by being covered with an impermeable sheet ora shielding container bag, etc., no serious problem due to deterioration or the like has occurred. The service
life of the water impermeable sheets is assumed to be 15 years, and with proper inspection and repair it isconsidered that there is no major functional impairment.
Table 4-6 Examples of flexible containers and large container bags
Type

Image

Flexible
container(cross shape)

Characteristics· Assumed to be used once for full life.
· Inferior in weather resistance and waterproofness
compared to running type.
· Some types have improved weather resistance with
UV treatment, some with inner bags, some withimproved waterproofness by inner coating, etc.
· Assumed to be filled and emptied repeatedly.
· Excellent weather resistance and waterproof qualities.

Flexible
container(running
type)
Large
container bag· Water permeable.
· Some types have improved in weather resistance with
UV treatment, some made more waterproof with inner
bags, etc.

When storing removed soils, etc., generated by decontamination in theSpecial Decontamination Area,
the material is to be classified ① to ⑨ as follows based on the Common Specifications for
Decontamination and Other Work..
Table 4-7 Storage classification of removed soil etc.
Combustible
material

Incombustible
materials, ·Mixtures①Plants (pruned branches, deciduous leaves, grass, moss, weeds, litter layers,
harvested trees, roots etc. Remove any attached soil, to the extent possible).
②Other combustible waste (Tyvek suits, cloths, masks, filters, rubber gloves, paper,
etc.)③Soil, etc. (soil, pebbles, gravel, etc. Remove plants, to the extent possible.)④Concrete pieces, etc. (tile, brick, blocks, rock, etc.)⑤Asphalt mixture230Dangerous
goods /
harmfulsubstances
Explanation⑥Other incombustible materials and mixtures (excluding dangerous goods,
hazardous substances)⑦Building materials containing asbestos⑧Gypsum board⑨Other dangerous goods, harmful substances

Strength testing of materials used in Temporary Storage Sites

Studies and research are also being conducted on whether sufficient strength is ensured during the storage
period, with materials (in containers, etc.) used to store the removed soil, etc., at the Temporary Storage
Sites

Tensile strength test of

Lifting and suspending

storage container belt

test of storage

Drop test of container
bagcontainer
Source:Fukushima Prefectural Centre for Environmental Creation

An enormous quantity of removed soil, etc., is generated by decontamination, so it is essential to reduce
the overall volume so as to reduce the volume that needs treatment and disposal, and for securing land forstorage. Methods of volume reduction include physical volume reduction such as compression andcrushing, incineration and melting, and “separation” (bunkum) in which fine particles such as clay withradioactive cesium attached are sorted and reduced. On location where decontamination is carried out toaim volume reduction by crushing, chipping, and compression, etc. Examples are provided below.
① Crushing
Branches cut down in the process of decontamination of forests are generated in large quantities, will
have a large ratio of air space, and will be a waste of space even if an attempt is made pack them up.
Therefore, the branches are crushed using a crusher and packed in bags to reducing the air space.

231

Credit: Okumura Corporation
Figure 4-33 Cut branches (left) and crushing facility (right) to process branches from forest
破砕ヤード内の作業（破砕、袋詰め）
decontamination work
フレコン詰

破砕

投入

可燃物の集積Credit: Okumura Corporation
Figure 4-34 Inside the crushing facility: Bundling (left), crushing (center), filling the flexible containers(right)② Chipping
Decontamination waste generated by decontamination, such as branches and leaves, is reduced bycrushing to the size of chips. There are examples of self-propelled wood crushers being used in residential
areas, etc.

Figure 4-35 Before chipping (left) and after chipping (right)
Source: MOE, Fukushima Office for Environmental Restoration “Compilation of Good Examples of Decontamination”(May 2013)

Fig. 4-36 Chip forming device

Source: Ministry of the Environment Fukushima Office for Environmental Restoration “ Compilationof Good Examples of Decontamination” (May 2013)）

232

③ Compression, packing
Crushing and chipping are examples of decreasing the air spaces and reducing the volume by crushing thewaste. The crushed material is further reduced in volume by vacuum compression. This volume reduction
technique uses vacuum compression and a compression bag. One common problem is clogging by leaves,etc., and puncturing of the compression bag by branches and leaves which can be solved using special
nozzles and special compression bags. This technique can reduce combustibles such as fallen leaves,branches, and grasses to one-half to one-third of their original volume.
There are also examples in which combustible materials such as plants and branches are compressed,
shaped into a roll, and packed with wrapping so as to reduce volume and decomposition, in order to ensure
the effective utilization of Temporary Storage Sites and keep the material manageable during the storage
period.

Credit: Maeda Corporation

Fig. 4-37 Compression packing device

Credit: Shimizu Corporation

Fig. 4-38 Combustible material reduction / anticorruption device

Credit: Taisei Corporation
Figure 4-39 Before Compression (Left) and After Compression (Right)
Management of Temporary Storage Sites (Special Decontamination Areas)

After the delivery of removed soil, etc., is completed and the work of shielding the top surface is done,
the decontamination contractor will manage until the handover of responsibility is completed, andcontractors designated by MOE will take over the site management.
For the management of Temporary Storage Sites, MOE prepared the “Temporary Storage Site
Management Manual” to prescribe site management systems, inspection and management items,

233management techniques, and monitoring items, etc. In addition, a “Maintenance and Repair Manual(provisional operation)” has been created. Both manuals are lent to management companies contracted formaintenance and repair work at Temporary Storage Sites, etc., and their work is carried out according tothese manuals.

Protection layer (approx.t=100mm sand)Upper protective mat(.t=10mm)
Water shield sheet (.t=1.5mm)
Lower protective mat(.t=10mm)

Detailed structure of thebottom part (example)

Daily inspection once a week

・Visual inspection
・Measurement of air dose rate

Daily inspection once a month ・Measurement of groundwater
When necessary

・Measurement and treatment ofleachate in the catchment tank

Emergency inspection at the time・Visual inspectionof extreme weather and earthquake ・Measurement of air dose rate

Figure 4-40 Basic design of Temporary Storage Sites plus daily management and inspection (site in aSpecial Decontamination Area, example for combustible material)
At Temporary Storage Sites in Special Decontamination Areas, it is necessary to periodically check forthe presence of stored water in the discharge water collection tanks, check the radioactive cesium
concentration if a certain amount of water accumulates in the tank, and discharge it only after ensuring it
is below the control value (Cs-134 concentration [Bq/ℓ] / 60 + Cs - 137 concentration [Bq/ℓ] / 90 ≤ 1). If
the control value is exceeded due to soil and material entering in the tank, the water is transported to awater treatment facility, subjected to coagulation sedimentation or other treatment, and then discharged
only after confirming that it is below the control value.
In addition, visual and other inspections are conducted once a week, and if any trouble is noted, repairs
or other actions are promptly carried out, and steps are taken so as not to let the trouble worsen. Up to now,
the main repairs have been as follows.
·Water pooling occurred on the upper sections of impermeable sheets above the stored material, so
pumps were used or drainage was created on the top.
·Weeds were growing on shielding container bags and retaining mounds, so the weeds were removed.
234

· The covering sheet was damaged, so it was repaired with repair tape.
Municipalities conduct inspections of Temporary Storage Sites in the Intensive Contamination Survey
Areas, and the prefecture and MOE also conduct patrol surveys and confirm the storage condition ofremoved soil, etc. As a result of the patrol surveys, cases such as partial damage of storage containers wereconfirmed, but no discharge of removed soil, etc., was confirmed.。

Cratering on the top end
On storage piles of decomposable decontamination waste, examples of rainwater accumulation wereobserved in depressions on top due to uneven settling from compression of the stored materials, as a resultof decomposition of organic matter. For this reason, measures were taken to eliminate rainwater by creating
low parts of the shielding container bags, to eliminate rainwater by holding the top end in an arch shapeby using urethane foam or a settling prevention plate. There is an example in which a mesh sheet is laid ina layer of the stored material to prevent uneven settling.
Capping
sheet
キャッピングシート

メッシュシート
PDDX#500
Meshsheet PDDX#500
メッシュシート
PDDX#500
Meshsheet PDDX#500

0.75m ormore

Credit: Taisei Corporation
Fig.4-41 Example of preventing cratering on top
Leachate treatment
Since the bottom sheet should block water coming up from the ground, and the top sheet should blockrainwater, any leachate at Temporary Storage Sites should normally only be water that accumulates in theleachate tank coming from the stored materials, and it should gradually decrease. However, in some cases,
water came in via seam joints in sheets and the infiltration of rainwater from the breathable sheet, etc., thegeneration of the leachate water did not converge in some cases. For this reason, in addition to repairingseams of the sheets, measures were taken such as covering entire storage piles with impermeable sheets.

235

In MOE document on Common Specifications for Decontamination and Other Work it is specified thatthe tags attached to containers such as flexible containers should have information readable for at least
three years under a series of conditions, including decontamination measures, delivery to a Temporary
Storage Space, and storage, and be made of materials and have a surface treatment (only for non-hazardous
items) to make them corrosion resistant, weather resistant, and durable, and have tag colors to identify thecontents.
As the decontamination work progressed, some decontamination contractors developed and utilized QR
code printing systems, selecting and typing in necessary information with a handheld input device.
When full-scale decontamination began there were no unified specifications for the management of theselarge container bags, so in some cases workers simply hand-wrote information on the bags using marker
pens, but after receiving suggestions from decontamination contractors about using tags, MOE included
the concepts in Common Specifications for Decontamination and Other Work.
Table 4-8 Correspondence between content and tag color in Special Decontamination Areas
A
B
C
D
E
F

Color
White
Green
Yellow
Blue
Black
Red

Contents
Soil, etc., (soil, pebbles, gravel etc.)
Decomposable combustibles (pruned branches, deciduous leaves, grass, moss, weeds,
litter layers, harvested trees, roots, etc.)
Combustible materials (Tyvek suits, cloths, masks, filters, rubber gloves, paper, etc.)
Incombustible materials (concrete pieces, etc. [brick, blocks, rock etc.], asphalt mixture,sludge etc.)
Incineration ash
Dangerous goods (asbestos-containing materials, soil contaminated with harmful
substances, etc.)

Development of “QR code issuingsystem”
・Handy-type input machine which
can select necessary items anddose
・Transfer of data and issuing QR
code
・Data are able to be assembled into
personal computer with productformat to decontamination
information system

Credit: Kajima Corporation

Figure 4-42 Example of QR Code Issuing System in Special Decontamination Areas

Documents entitled “Outbound Transport Consideration Items (Provisional Operation)” and “Methods
to Restore Original Conditions (Provisional Operation)” were prepared by MOE concerning how totransport the removed soil, etc. away from the Temporary Storage Sites and how to restore the original site
conditions when returning the land.

236

Quantities of Removed Soil, etc.

In Special Decontamination Areas, as of the end of December 2017, about nine million bags of removed
soil, etc. had been generated and stored at 242 Temporary Storage Sites.
Table 4-9 Statistics on quantities generated
As of December 31, 2017
Municipality

Temporary
Storage Sites(number)Quantity
generated(number of bags)

Tamura City

5

38,962

Naraha Town

21597,241

Kawauchi Village

295,444

Okuma Town

15467,229

Katsurao Village

25565,289

Kawamata Town

43629,467

Futaba Town

4

202,359

Iitate Village

84

2,502,019

Tomioka Town

8

1,593,069

Namie Town

22

1,336,311

Minamisoma City

13

1000,478

Total

9,027,868
242
注 Notes: 1. The number of Temporary Storage Sites includes Temporary Storage Sites, and shortterm storage space.
2. The volume of stored material per bag is about 1 m3 (although one bag may become smaller
than 1 m3 due to the volume reduction of stored material). In the future, quantities of stored
material may increase due to supplemental decontamination, etc.

237

With decontamination in Special Decontamination Areas, looking by municipality at the relationshipbetween the size of the area where decontamination was implemented and generated amount of
decontaminated soil, etc., the amount of removed soil increased in correlation with the size of
decontamination area

Removed soil (mil. m3)

A-I : Munucipalities(SDA)

Decontamination areas(1000 ha)Note: Vertical axis: Amount of removed soil [m3] (Amount of stored soil, etc., in
Temporary Storage Sites (converted as 1 m3 per bag))Horizontal axis: Decontamination implementation area [ha] (total for residential
land, agricultural land, forests, roads)
Figure 4-43 Decontamination Area and amount of removed soil, etc.
Source: MOE (editor), TEPCO Holdings

238

Regarding decontamination in the Intensive Contamination Survey Areas, as of September 2017,about 6.47 million m3 of removed soil, etc., was stored at about 170,000 on-site storage sites, and 887
Temporary Storage Sites.
Table 4-10 Statistics on quantities generated of removed soil, etc.
On-site storage

Municipality
Fukushima
Prefecture
Iwate
Prefecture
MiyagiPrefecture
IbarakiPrefecture
Tochigi
Prefecture
Gunma
Prefecture
SaitamaPrefecture
Chiba
Prefecture
total

Temporary Storage Sites
Quantity

Total
Quantity

Quantity stored

Locations

Locations

1,850,890

137,266

4,144,330

843

5,995,220

12,128,549

26,484312

0026,484

312

16,676674

80,06329

96,738703

55,139

1,045

2,657

2

57,796

1,047

175,442

25,1626,119

2181,561

25,164

3,338

781

1,836

7

5,174

788

6,634

46

650

2

7,284

48

101,085

1,729

70

2

101,155

1,731

2,235,688

167,0154,235,725

887

6,471,412

167,902

storedstoredNote: For Fukushima Prefecture the numbers are as of the end of September 2017.

239

Locations4.5. Organization and Management of Decontamination Work in Special Decontamination Areas
Securing the Necessary Resources through Decontamination Contractors

The decontamination work needs to be performed according to the state of the radiation dose and thestate of the decontamination target, etc., and since the work that can be mechanized is limited, a large
number of decontamination workers are necessary. In order to secure these decontamination workers,
workers had to be hired not only locally but also from outside the prefecture.
However, the Earthquake off the Pacific coast of Tohoku that caused the TEPCO Fukushima Daiichi
Nuclear Power Station accident caused serious damage mainly in Miyagi, Iwate and Fukushima
Prefectures. In Miyagi Prefecture and Iwate Prefecture, etc., large-scale restoration and reconstruction
projects have been progressing since the earthquake disaster, and the demand for civil engineering workers
for decontamination work, etc., was also large outside Fukushima Prefecture. Therefore, securingdecontamination workers was extremely difficult.
Therefore, in MOE, local governments, etc., explained efforts to reduce concerns about becoming
decontamination workers by introducing decontamination work in an easy-to-understand manner, and inSpecial Decontamination Areas also worked on securing decontamination workers by implementing
measures such as paying special work allowances.

Decontamination work requires a certain level of knowledge of radiation and decontamination methods.
However, decontamination work was the first experience in Japan, and not only workers but also
contractors of decontamination works had little knowledge and experience concerning decontamination
and radiation protection. In addition, there were many workers who had no experience of construction
work, and there were many cases where knowledge was insufficient for safety management, which isotherwise common knowledge at typical work sites. For this reason, efforts were made to educate a large
number of workers about various matters, such as decontamination work, radiation, safety and health.
For example, before each worker enters the decontamination site for the first time, in addition to
conducting new entry visitor education by special education based on the Ordinance on Prevention of
Ionizing Radiation Hazards or a separate program, each contractor promotes full knowledge by repeatedly
conducting continuous education, safety measures, etc. In addition, because Fukushima Prefecture andMOE held workshops for workers and field supervisors, decontamination contractors were able to develop
educational activities more smoothly and easily.
Various accidents and troubles occurred along with the progress of work, and the content of education
expanded in response, and in addition to improvement of the initial content on radiation protection
measures and work safety, efforts were also made to raise awareness through explanations about thenecessity and significance of decontamination work, and also education was also conducted concerning
consideration for the local community and regulatory compliance.

240

In parallel with the decontamination work, in the disaster area, restoration and rebuilding work from thedisaster caused by the earthquake and tsunami was being done, making it a challenge to secure thenecessary quantity of specialized equipment among the equipment and materials used for decontamination
work. In general, specialized equipment is expensive, so it is necessary to consider the efficiency
improvements to be gained and cost-effectiveness of introducing the equipment. Also, particularly at theearly stage of the decontamination operations, the equipment leasing companies were concerned about
their equipment being contaminated by radioactive substances, making it difficult to conclude lease
contracts.
Therefore, in addition to effective use of equipment used for general civil engineering work, in someinstances decontamination contractors also used agricultural equipment for decontamination work (in thecase of decontamination contractors, there were cases of employing local farmers and utilizing the
agricultural machinery they already owned for decontamination work).
For most of the equipment could be decontaminated, such as by wiping it off after use, in order to meetcriteria for contamination inspections, and then be returned to owners.
Regarding protective clothing and protective equipment, etc., by following the Ordinance on Preventionof Ionizing Radiation Hazards as well as the guidelines for that Ordinance, workers what was required,and avoided increasing waste that would have been generated by using excessive protective clothing andprotective equipment, etc.
At the peak of decontamination work, each site in the Special Decontamination Areas would have aworkforce of a few thousands up to 10,000 people, and accommodations were needed for these workers.
However, as Special Decontamination Areas were evacuation areas, existing accommodation facilities
were not operating, and accommodation facilities were limited in the surrounding municipalities, so there
were also challenges with securing traffic routes and dealing with traffic congestion for daily commuting.
For this reason, although in principle, accommodation is prohibited in Preparation Areas for Lifting of
Evacuation Orders, because accommodation is specially approved in cases where it was necessary forreconstruction, there were some examples of workers’ dormitories being established with the cooperationof municipalities and the understanding of the local people. On
such occasions, efforts were made such as starting bydecontaminating schools and public facilities on land owned bymunicipalities, then setting up the workers’ lodgings, andcarrying out security patrols of lodgings.
In addition to increasing the number of workers withincommuting distance within the prefecture, efforts were also madeto secure lodgings in various places, such as reducing the number

Credit: Okumura Corporationof vehicles on the road by using commuter buses, staggering

Figure 4-44 Example of a workers’commuting times by setting different work start times, anddormitory(capacity about 350 people)

dispatching traffic guides, etc.

241

In decontamination work it was necessary to earn the trust of landowners and it was important to gain
local cooperation. Efforts were made to promote employment of local companies and local residents, andaccording to a survey by the Japan Construction Federation (February 2017), about 40% of all workers
lived within the prefecture.
Many workers with no experience of engaging in construction work were hired, so a greater effort thanusual was made to promote safety education, etc. Also, because of the unfamiliar working environment,
quite a few workers quit after a short period of time, but local workers had a high degree of attachment tothe area and this led to careful work.
In order to facilitate decontamination of agricultural land, it is important to communicate to gain
understanding of owners and cultivators of agricultural land. For that reason, farmers were hired directly
as workers of cooperating companies, they brought in their tractors for the work, and various efforts weredone to utilize their agricultural expertise and experience in decontamination work. By having farmers
decontaminating their own farmlands, the speed of agricultural land decontamination was accelerated. An
effort was made to secure trust by having farmers working to decontaminate agricultural land.
Equipment and foods, living supplies were procured at local shops as much as possible.

242

Project Management by Decontamination Contractors (Special Decontamination Areas)

Some areas such as the Aizu area in Fukushima Prefecture have high snowfall and snow accumulationin winter. In decontamination work, errors can arise in the measurement of air dose rates and surface dose
rates due to snow accumulation, quality can deteriorate when confirmation of decontamination work
becomes more difficult due to snowfall and snowfall accumulation, and workability and safety can decline.
It was therefore decided not to perform decontamination work during the snowy season and the snowfall
period.
In the case of rainy weather as well, errors can arise in the measurement of the air dose rates and thelike, materials being removed can be washed away and increased moisture levels can increase the weight,
leachate from removed materials can accumulate at Temporary Storage Sites, and rainwater canaccumulate when the temporary covers are lifted for delivery at Temporary Storage Sites. It was therefore
decided to stop the decontamination work when there is more than a certain amount of rainfall, and work
plans were formulated and work was scheduled based on weather conditions.

The designation of persons (work leaders) who lead the work for each work unit (work team), persons
responsible for radiation control (radiation control managers) were designated to supervise the radiation
control of workers doing decontamination and other work.
Lists were prepared of workers working on decontamination and other work. Decontamination workers
were registered on the list before starting work and their registration was removed when they ceased to beengaged in the work. It was confirmed that they possessed an individual dose record book at the time ofbeing registered as decontamination workers, and if they did not have one, they were required to obtain
one before cancellation of registration.
Applications for decontamination worker identification cards were submitted to supervisory personnelat MOE, the identification cards were issued, and decontamination workers were required to carry them at
all times when working.
Since a large number of workers would enter and exit the work areas, in order to smoothly conduct therecording of worker name, work hours, and exposure doses, etc., in some cases facial recognition andfingerprint authentication devices were used.

243Credit: Kajima Corporation

Figure 4-45 Example of implementation system of decontamination work

Credit: Kajima Corporation
Figure 4-46 Examples of entry/exit management systems using fingerprint authentication devices

Besides the primary contractors, implementation work required the involvement of large numbers ofcooperating companies and workers, so it was a challenge to have adequate communication of notifications
and safety precautions, etc.
For this reason, there were also many examples of communicating notifications and safety precautions.
These included coordination meetings to confirm progress and exchange information concerning
decontamination work, held regularly between the Fukushima Office for Environmental Restoration(MOE), municipalities, labor standards supervision departments, police, fire departments, and primarycontractors (joint ventures), as well as meetings and updates, morning and lunchtime briefings, held at
various levels of authority among joint ventures, cooperating companies, and work zones.
244

Credit: Kajima Corporation
Fig. 4-47 Example of communicating notifications

Credit: Maeda Corporation
Fig. 4-48 Example of a work coordination meetingand safety precautions

The management of work quality is crucial, because decontamination involves work to reduce radiation,
which is invisible to the eye, and it is also difficult to establish target values for radiation doses after
decontamination.
Therefore, with each decontamination method, in order to demonstrate the expected decontamination
effects, procedures manuals were prepared indicating specific procedures for decontamination methods
indicated in Decontamination Guidelines and specifications, workers were educated, and extensive efforts
were made to apply the established work procedures. In addition to the decontamination techniques, theprocedures manual also describes the supervisory role of decontamination contractors, methods of usingmaterials and equipment for decontamination work, methods of confirming and ensuring work safety, andresponses during extreme weather and emergencies.
These procedures and quality control methods were revised based on trial and error and knowledge in
the actual decontamination work. In the case of revision of work procedures, etc., measures were taken to
inform workers about the changes, such as holding meetings to fully communicate the information.

Credit: Maeda Corporation

Figure 4-49 Example of extensive notification system for work procedures
245

Medical examinations for ionizing radiation from decontamination, etc., and testing of internal
exposure doses
Workers regularly undergo medical examinations for ionizing radiation from decontamination,
including when they are hired or leaving employment, and are measured using whole body counters forradiation doses by internal exposure.
To secure the decontamination contractors ensure that workers receive dosimetry for internal exposure,
MOE on behalf of the national government established one whole body counter clinic at one location in
Naraha Town (later moved to Tomioka Town) and one in Minamisoma City, and persons engaged indecontamination work were able to use them free of charge.
Measures at work
From the viewpoint of radiation protection, decontamination contractors conducted various efforts to
reduce the exposure doses received by workers. For example, rest stations were set up near thedecontamination work sites, and there was a thorough effort to ensure that when the workers would eat
and drink, etc., they would be doing so at rest stations, not outdoors at the decontamination sites. Where it
was difficult to set up or use a resting place, a thorough effort was made to ensure workers would consume
food and drink inside a vehicle.
Exposure management of workers
Decontamination contractors had their workers wear personal dosimeters to measure the external
exposure dose before starting and after finishing work every day, and managed the external exposure doses.
In decontamination work, based on the Ordinance on Prevention of Ionizing Radiation Hazards, it wasalso mandatory to conduct surface contamination inspections (screening) so workers would not bring out
radioactive materials pollution sources from the workplaces.
At the actual decontamination sites, it was a challenge to screen a large number of workers, and to havethe screening of workers concentrated at a specific time of the day (at lunch, end of work, etc.). Therefore,
some decontamination contractors achieved efficiency improvements and labor saving by automating thescreenings during breaks, lunch and upon exiting from decontamination work.

Credit: Kajima Corporation
Figure 4-50 Example of mechanization and automation of screening

246

Unified management of exposure dose
Although the exposure dose of workers was managed by each decontamination contractor based on the
Ordinance on Prevention of Ionizing Radiation Hazards, since workers often moved between thecontractors, there was a need to centrally manage the data on exposure doses recorded by each contractor.
For this reason, in November 2013, it was decided to establish the System of Registration and Managementof Radiation Exposure Doses for Decontamination and Related Work and to centrally manage the exposure
dose information of decontamination workers through the Radiation Workers Registration Center of the
Radiation Effects Association.
Each decontamination contractor regularly submits the exposure dose of the workers to the Registration
Center, and the exposure doses of the worker are centrally tracked based on central registration numbersin their individual dose record book.
According to the records of the Registration Center, the number of workers engaged in decontamination andother operations was 76,951 over the five years from 2012 to 2016, and the exposure associated withdecontamination work averaged 1.0 mSv. Even among the workers with the highest radiation doses, the dose
was less than 20 mSv over the period of five years.
Table 4-11 Exposure doses of workers engaged in decontamination work over five years (2012-2016)
Dose (mSv)

Workers (%)

1 or less

51,354 (66.7)

More than 1 and less than 523,998 (31.2)

More than 5 and less than 10

1,465 (1.9)

More than 10 and less than 15

123 (0.2)

More than 15 and less than 20

11 (0.0)

More than 20 and less than 25

0 (0.0)More than 25 and less than 30

0 (0.0)More than 30 and less than 40

0 (0.0)More than 40 and less than 50

0 (0.0)More than 50 and less than 60

0 (0.0)More than 60 and less than 70

0 (0.0)More than 70 and less than 80

0 (0.0)More than 80 and less than 90

0 (0.0)More than 90 and less than 100

0 (0.0)More than 100

0 (0.0)Total no. of workers (%)

76,951（100.0）

Average dose (mSv)

1.0

Source: “Dose Statistical Data Based on the Information Registered with the System ofRegistration and Management of Radiation Exposure Doses for Decontamination and Related
Work ” (Registration Center of the Radiation Effects Association, 2016), compiled by MOE.
Note: This is the dose distribution for workers engaged in decontamination operations over the five
years from January 1, 2012 to December 31, 2016. The dose for 2011 is added to the dose for 2012.

247

High temperatures and sun exposure in the summer are factors creating a harsh working environmentand greatly affect the health of decontamination workers. To cope with such a situation, in workplaces witha large number of workers, in addition to cautionary warnings, various measures were taken to prevent anddeal with heat stroke in consideration of weather conditions, including wearing protective clothing fittedwith ice packs, and avoiding work during the hottest hours.

In the Areas under Evacuation Orders, water supply and sewerage systems, and waste disposal facilities,
etc., had stopped functioning due to damage and evacuation caused by the earthquake disaster, so
processing was performed by neighboring processing facilities and in some cases their buffer capacity was
lost. Thus, processing was initially left to the responsibility of the decontamination contractors, but
eventually the national government exchanged information with processing facilities in othermunicipalities, etc., confirmed the decontamination work plans and the extra processing capacity in thearea, and took measures to avoid negative impacts.

Damage was caused by wild boars in many areas from where local residents had evacuated, due to thelack of a human presence as their natural enemy, and due to the corresponding increase in breeding.
Damage was frequently caused by wild boars digging for worms as food, after cloth sandbags had beenplaced to prevent runoff after excavation for decontamination, and the only option was extermination. In
addition, any cattle and other livestock discovered were promptly reported to the municipal offices andactions requested.
Education for Decontamination Workers (Special Decontamination Areas)

When workers enter a decontamination site for the first time, they received a training covering theoutline of work, safety policies at the workplace, basic safety and health rules, safety and health events,
workplace safety rules, and considerations for residents.
In addition, safety and work education included workplace policies showing workplace safety priority
items and concrete implementation guidelines, and past case examples and patrolling results werecompiled and classified according to case examples in “Essential Workplace Safety Rules.”Employees are informed of work procedures by a publicity brief based on work procedures manuals forindividual work, local education for improving the understanding of workers, and decontamination
optimization education.
Regarding decontamination special education, which is legally mandated and separate from the training
provided when workers first enter a worksite, training is implemented based on the “Textbook for Special
Education on Decontamination Operations” (Japan Industrial Safety and Health Association). Traditionally,
this education would be offered by a worker’s direct employer, but in this case the primary contractors
248themselves are providing the trainings to all workers, rather than treating it as the responsibility of thesubcontractors.

Credit: Kajima Corporation
Figure 4-51 Example of education and training flow for decontamination workers
Table 4-12 Example program of safety education for newly employed workers.
1
2
3

ProgramConfirmation of
employment agreement
Work outline
Safety policies at theworking place4

Basic rules of safety andsanitation

5

Activities relevant tosafety and sanitation
Tidiness and order
Risk potential prediction“KY”
Harmonization with thecommunity
Safety rules on duty

6
7
8
9
10

Instruction to receive
WBC checks

Key contents
Confirmation of the company to belong to, minimum wages, special
duty allowance, medical checks
Explanation of an outline of jobs to do
Explanation of safety policies at the working place
Prevention of falling down
Prevention of minor collision between men and heavy machinery
Prevention of minor collision between men and mowers
Radiation and health care, other related topics
Explanation of basic rules of safety and sanitation
Consideration to give to local residents
Dose measurements and contamination inspections
Safety equipment
Practice to carry Identification Card and armband
Information on work plans and work procedures
Smoking, eating and drinking
Responses to take when injured
Traffic rules
Explanation of activities relevant to safety and sanitation
Explanation of the rules to keep working places tidy and in order
Explanation of the process to predict risk potential for sharing KY: anacronym of “Risk potential prediction” in JapaneseExplanation of consideration to give to local residents
Explanation of “22 musts in safety rules” which assembled the cases
experienced and the results found during patrol for each of selectedcases
Description of WBC reception and cautionary points
Credits: Maeda Corporation249

In addition to the training provided to workers upon first entering a site, regular education was also
provided, including regular weekly and monthly education, periodic events such as work proceduretrainings, and one-off trainings to inform workers about major problems, etc. In order to educate many
workers, in some cases training sessions with over 100 workers were held daily.
The various seminars did not rely on one-way teaching, but rather, an effort was made to keep them
relevant and dynamic, with discussions and sharing of personal experience, introduction of positive
examples, the use of visual and easy-to-understand teaching materials with diagrams and video, and guided
inspections by model group leaders, etc.
Adjustments were made to provide different levels of learning content, for example, by offering different
material for workers, managers (group leaders) and primary contractor officials. Inexperienced newworkers wear a novice sticker on the helmet so they can be identified, and an effort is always made to havenovices assigned to working groups to be together with experienced workers.
In addition, special education was provided on-site for local construction company officials and workers,
etc., and support was also provided to obtain certifications.
Regarding consideration of local communities and regulatory compliance, in addition to education on
promises that had been made to local communities, workers received education on behavior outside ofwork, from daily life attitudes to prevention of drunk driving.

250

Credits: Maeda Corporation
Figure 4-52 Example of regular safety education

Credit: Shimizu Corporation
Figure 4-53 Examples of education using videos
and images

Credit: Maeda Corporation
Figure 4-54 Examples of safety activities

Credit: Maeda Corporation
Figure 4-55 Example of on-site training

Figure 4-56 Example of making things clearly visible
for new workers

251Credit: Taisei Corporation
Figure 4-57 Example of education for regulatory compliance252

Since decontamination differs from work such as civil engineering and construction to build structures
and the results are harder to see, the feeling of accomplishment can be low and work can feel monotonous,
with negative impacts on worker morale and alertness, resulting in a decline in the quality ofdecontamination work.
In order to improve and maintain the motivation of workers, guides like the “Eight Rules ofDecontamination” and “Ten Commandments of Decontamination” were devised as codes of conduct fordecontamination worker. Efforts were made to raise awareness and have workers internalize them byreciting them together in daily morning briefings and the larger safety gatherings, etc.
Also, at seminars and other opportunities, efforts were made to raise worker awareness and improve thequality of decontamination by repeatedly mentioning that the purpose of decontamination is to reduce theradiation dose and prepare an environment for disaster victims to return home. In addition, activities toheighten the motivation of workers were also developed by awarding excellent workers and employees.

Credit: Shimizu Corporation
Figure 4-58 Example of large group at daily morning
gathering reciting mottos for decontamination

Figure 4-59 Example of code of conduct fordecontamination workers
Credit: Maeda Construction Co., Ltd.

253

Credit: Maeda Corporation

Column“Work management systems and safety management”
Mr. Takashi Mizutani, Hazama Ando Corporation

In decontamination work in Namie Town, 26 administrative districts were
decontaminated, and an enormous number of workers, up to 4,000 per day, were
engaged in the work. The decontamination ranged from areas with relatively low air
doses such as Preparation Areas for Lifting of Evacuation Orders, to broad areas
such as Areas where Returning is Difficult along National Road No. 114. It wasnecessary to do daily counts, checks and controls of the daily cumulative exposure
data for all workers. Actually, from the result, some work exceeded the voluntary
control values, so we imposed limits on the working hours.
We used a “Decontamination Integrated Management System” for this management. It is a cloudbased database system that can handle an enormous amount that would be impossible manually, and it
centrally manages data that can be shared among users, including worker exposure data, monitoring
results before and after decontamination for each landowner, information on flexible containers at
Temporary Storage Sites, and more.
Utilizing this system, we conducted a wide range of tasks, including work progress and processcontrol, the creation of decontamination reports, and safety documentation management, etc., to perform
safe and reliable daily decontamination work.
For safety management, we assigned personnel in charge of safety in each administrative district. In
cooperation with JV officials and the heads of cooperating companies, the safety personnel work performdaily patrols to ensure that qualified personnel are assigned according to work plans, that work
procedures are being followed as planned, that there are no unsafe facilities, and that no unsafe activities
are happening. In addition, one full-time spotter was assigned to every machine for work with heavymachinery. Originally there was some confusion, but everyone is now trained so everyone understands
that the spotter’s duties are indispensable for preventing heavy equipment accidents, and it is now a habit
not to work in the absence of a spotter. In addition, we set up six separate locations for morning
assemblies of workers, where we gave appropriate safety instructions according to the situation in the
district of responsibility, and we also handled worker health management in a way that we could actually
see the individual workers.
We conducted safety education every month to raise the safety awareness of personnel and workers
and boost safety activities. As presenters, we actively invited outside speakers from various organizationsin an effort to avoid taking safety for granted and to provide the latest information. Speakers came fromthe Japan Construction Occupational Safety and Health Association, Futaba and Minamisoma Police
Stations, Namie Fire Department, Tomioka Labor Standards Office,the National Health Insurance Society, JAF, and our own headquarters
and branch offices, etc. For site managers and key personnel ofcooperating companies, as a part of our monthly CSR education, we
also explained accidents and labor troubles that had occurred in otherwork, as we aimed to work together with JV and cooperatingcompanies to prevent various problems.

254

Regarding traffic measures, before evacuation orders were lifted, all workers were commuting fromout of town. Moreover, most of the personnel and workers were commuting from afar, and the only roads
available for commuting were National Roads No. 6 and No. 114. For this reason, from the viewpoint ofprevention of traffic accidents and traffic congestion, we set up six decentralized locations for themorning assembly of workers and monitoring facilities, and this helped to prevent the concentration ofvehicles on the road.

ColumnImproving radiation dose management systems”
Mr. Takeshi Nishikawa, Kajima Corporation

In decontamination work, the first step in organizational management is to manage the worksite entry
and exit of more than 2,000 workers (data about when, who, where, until when, exposure doses,
screening implementation).
In the initial emergency decontamination work, we used barcode cards forindividual workers, but for the full-scale decontamination work in Tomioka Town
three years after the earthquake, we developed and operated an individual
identification system using fingerprint authentication. By doing this we can prevent
entry by false substitutes and prevent inflated hour claims, while having reliable entry
and exit control. In addition, since it is an endless (open ended) database, we canconduct instant searches and data compilations of the whole database or by company or individual, andthis connects to reliable radiation management.

Column“Conscientious decontamination work”
Mr. Yoshio Shimizu, Taisei Corporation

Challenges faced in decontamination work
1. The area of work is extremely large and created challenges for management
operations (about 230 square kilometers)
2. Maximum number of workers is on a scales we had never before experienced(about 6,000 workers/day)
3. Many workers had no previous experience in construction industry (civilengineering, construction, etc.)(About 4,800 (80%) of approx. 6,000 workers are inexperienced.)
November 2017 marks the start of our sixth year engaged in decontamination work.
In this work, we have been engaged in decontamination of a vast area that includes residential areas,
forests, farmland, and roads (approx. 230 square kilometers, greater than the area inside the circular
Yamanote rail line in Tokyo). Decontamination work is something no one had experienced before, so all
the company personnel and the workers engaged in this work were inexperienced. Above all, the mostimportant thing for us as a primary contractor was to raise theawareness of everyone involved, by having company personnel
acquire solid knowledge and then be able to explain to workers thatknowledge in detail, of course, but also the purpose, the importanceof the work, and the work methods, etc.

255

About 6,000 workers are engaged in the decontamination work per
day at peak times in Iitate Village. One of our responses to these

Morning Briefing

challenges was to compile “workplace rules” onto one paper to be learned by workers when they firstenter a worksite (attention to safety management, local conditions to be noted, etc.) and also video
training (decontaminate methods), and these materials are being used by the group leaders in charge ofeach area to raise awareness of all workers.
Going forward, we will continue to conduct the day-to-day decontamination work safely with carefulattention (slowly and carefully) by conducting on-site to ensure the contents of the education are being
carried out.

Column“Restoring Katsurao Village to pre-disaster conditions”
Mr. Hirotoshi Inoue, Okumura Corporation

The decontamination work was started on a scale that never before experienced.
In order to tackle this huge national project with courage and pride, with thedecontamination work in Katsurao Village as well, we used a variety of expertiseand performed the operations while making innovations and improvements.
① Establishment of work management systems
The area to be decontaminated was huge at 1,500 ha, and this was an enormous
project with 3,000 workers per day during the peak period, so we set up a
supervising organization for the entire project, and with that at the top, we divided the village into threework zones. All instructions, orders and essential information were transmitted top-down from thissupervising organization to each work zone and to each work team within each work zone, all at thesame time. Also, extensive reporting went from each work zone to the supervising organization, theinformation from the reports was fed back to all work zones, and this strengthened the vertical andhorizontal organizational collaboration.
② Safety management, labor management
For some of the workers this was the first experience in civil engineering work, and because theirawareness about safety and labor varied widely, we created a unified manual for all work and distributed
it to all the work zones. The manual included topics like a “Site Entry Manual” covering proceduresfrom new worksite entry to actual work, documents to submit, key points to note, a “Safety Bible(Katsurao Rules)” with details from planning to execution of each type of work, and so on. We also
launched a team focused on safety within the supervising organization, strengthened cooperation with awork team for each work zone, and actively carried out safety activities. In particular, we made “callingout” the basis of safety, with a campaign to encourage workers to communicate vocally with each on thejob, loud and clear.
③ Quality control
In order to ensure the quality of decontamination (dose reduction, etc.) and to eliminate variability
among workers, we created a manual detailing the procedure and method of work and measurement, anddistributed it in all the work zones. In addition, we implemented quality patrols by the work teams
located within the supervising organization to maintain and improve quality.
④ Gaining the trust of residents

256

It was a major precondition that we had to have the understanding and trust of residents andsurrounding local governments that had been forced to evacuate. We made sure everyone involved in thework was aware that they were responsible for a major national effort, and strove to maintaincompliance, discipline, and appropriate behavior not only during work but also in daily life. We gave
special attention to traffic accident prevention, such as awareness-raising for traffic safety compliancewhen commuting, and traffic safety campaigns linked with the efforts of police and surrounding local
governments. In addition to sharing information through discussion meetings (with the village andvillage council) on the progress of decontamination and on requests from the village, for the residents of
the neighborhoods, we also had a public relations team that included a local leader who joined us as astaff member. As a result of the establishment of the “Katsurao Reconstruction Project Cooperative
Association,” in which we cooperated, we helped promote local village businesses’ involvement in thedecontamination work, we were able to secure a valuable workforce from the village and neighboringmunicipalities and to gain their understanding and cooperation for decontamination.
Four and a half years have passed since we got involved, and though has been gradual, villagers are
beginning to return and the center of the village is coming back to life. I sincerely hope that Katsurao
Village will regain the natural and human vibrancy it had before the earthquake disaster.

Column“Work management systems and safety management”
Mr. Hideyuki Matsutani, Obayashi Corporation

I served as the site representative and supervising engineer in operations
including the Kawauchi Village Decontamination Project, Tomioka Town
Decontamination Project, Kawauchi Village Decontamination Soil Removal
Preparation Project, Futaba Town Interim Soil Storage Site Construction Project,
and the Interim Soil Storage Facility (Okuma Work Zone 3) Construction Project.
The following can be cited as challenges we faced.
1. Managing work over an extensive area (382 ha) and with a large number ofworkers (maximum 1,300 people)
2. Educating workers to acquire
knowledge on decontamination
methods and radiation
3. Maintaining workers’
motivation to do thedecontamination work
Particularly, for the work management system and safety management in
Tomioka Town, we created a system to divide the extensive work area into
three zones based on the local administrative districts and managed each as aseparate decontamination site. In order to manage a large number of workers,
we made the decision to create small work groups with just 10 to 15 workers
each, and created a command system with one task leader at the top of eachgroup. Also, since there were many inexperienced workers in the big workforce, we put novice stickers on helmets to help them be identified, andpaired them with veteran workers.

257

We held small seminars every week to provide knowledge on decontamination methods and radiationand to improve safety levels, and made sure that senior management from primary contractors also
attended.
Task leaders and workers with exceptional performance received awards of excellence at safetyassemblies which helped us maintain and improve the motivation for decontamination and safety work.

Column“Work management systems and safety management”
Mr. Masahiko Kashima, Shimizu Corporation

Many types of the work in decontamination depend on human power, which meansthat a significant number of workers are needed. Many were forced to evacuate due tothe nuclear plant accident and were unable to return to the jobs they had before thedisaster. So an effort was made to encourage the hiring of local people for thedecontamination work, and I was keenly aware of the difficulties of managing such alarge number of workers who had never before been involved in construction work.
What happens if the backhoe bucket comes into direct contact with a person? Whatif a person gets caught under the carrier of the transport machine ? We held safety seminars with theparticipation of all workers, using actual construction equipment and mannequins to show occupational
accidents that people would not usually have the occasion to see for real. The shocking scenes anddramatic sounds are beyond what people can imagine. The reactions were big, with people making
various comments, like “We cannot accept any injuries from heavy equipment. It’s like murder!” “We
need to be always alert and be risk-aware .” “Now I realize how unaware I used to be.” With these
activities we have had big results in improving overall awareness about work risks and work safety.
We will continue with our efforts to improve the work environment and safety management forworkers, and from these experiences we will strive for safety management that can trigger awarenesswithin the workers themselves.

258

Column“Work management systems and safety management”
Mr. Kenichiro Osawa, Maeda Corporation

One major characteristic of decontamination work is that a huge number ofworkers will work on a whole town and the work will be continuous on a yearlybasis.
The decontamination work itself was unprecedented for us in the constructionindustry. We had to manage it on a scale and sense of magnitude never yet
experienced, and that was a major challenge.
On the other hand, from the owners’ perspective the houses and fields requiring
decontaminating were “irreplaceable” and “one of a kind.” In other words, we had to manage a huge
number of cases, but at the same time, handle each one very carefully.
In order to address these challenges, Maeda Corporation utilized a “pyramid-type management
system” and promoted “quality assurance by emulating good work methods.”
This “pyramid-type management system” is a way to make clear the policies and the command andcontrol system, give each section its responsibilities and manage them. If we tried to give instructions toevery single worker on the frontlines, the time available for communication with each worker would be
relatively small, and as a result, detailed instructions might not reach everyone. For that reason, we
created a system in which staff direct the task leaders and the task leaders direct the workers, and eachstaff gave detailed instructions to the task leaders. As a result, detailed instructions reached all theworkers, and I think that this helped to eliminate loss and waste in the decontamination work, increase
productivity, and ensure a solid process.
With respect to promoting “quality assurance by copying good work methods,” we recorded videos of
exemplary work and by using the videos to promote those procedures all across the organization, we
could get our workers to accept them very quickly, and could ensure consistent quality indecontamination work. I think that there were also side benefits, because once the workers properly
understood the basics, they would come out with suggestions on how to further improve our methods. By
thoroughly instructing workers to emulate model work, we were able to encourage workers to be quality
conscious, and to eliminate each work group’s inconsistencies in decontamination quality, and I thinkthat we succeeded in providing consistent quality of decontamination work for the land owners.
Finally, about safety management, the key thing here was having thorough education for the task
leaders. What I felt from doing all of this is that a work team that has excellent safety management will
also be excellent in terms of work output and quality, and it will be a model of good performance for all
aspects of work. For safety management, we used a booklet entitled “Workplace Rules” to educate
workers. Because it was not only experienced
construction industry workers doing thisdecontamination work, if we imposed rulesthat were too difficult, they would not be
followed. I am confident that the reason wewere able to complete the work safely was
because we created the “Workplace rules”
based on easy-to-understand safety points that
we developed in the course of doing the work, were able to have the workers be aware of them directlyin the workplace, and could make safe work habits reach each and every worker.
259

Initiatives relating to Cooperation with Local Communities (Special Decontamination Areas)

Information exchange meetings were held generally on a monthly basis among three parties (local
governments, MOE, and decontamination contractors) to create a forum for discussing the current situationand future plans, plus items to note and confirm, etc., and the opportunities for communication were
beneficial for the progress of the decontamination work. Although 100% of municipal requests and so on
could not be taken up at the meetings, they were an opportunity to understand the needs of the local
governments and for the contractors to outline their concerns, and it is believed that they helped strengthen
the relationships with local governments.

Field visits
Initially at the beginning of the decontamination work, even with explanations of the details of
decontamination work and the safety of Temporary Storage Sites, etc., residents did not have theexperience of seeing the actual work or conditions, and so they ended up with concerns about safety and ageneral sense of anxiety. For this reason, on-site tours were conducted to show the decontamination work
and Temporary Storage Sites.
It seems that the general sense of anxiety could be removed by holding organized tours of thedecontamination work for town councilors, administrative district heads, and residents of the target
administrative districts, as well as allowing voluntary tours, to let people visually observe the details of
decontamination and its results. Regarding the Temporary Storage Sites, it seems that the sense ofresistance to their placement decreased because people could see that actual measurements of the air dose
rate near the sites were lower than before the Temporary Storage Sites were built. In addition, being able
to use a gamma camera or other equipment to visualize and explain the doses before and after
decontamination work on houses helped people understand the effects of decontamination which promoted
a better understanding of the work.
Provision of information on decontamination implementation status, etc.
Each decontamination contractor explained the content of the decontamination work and the status ofprogress, etc., in an easy-to-understand manner by means of illustrations and photographs by their websites
and publications, etc., and worked to raise the understanding of decontamination work.

260

Credit: Maeda Corporation
Figure 4-60 Information sharing with web-pages and hand-outs
Establishment of information provision facilities
Facilities such as “Decontamination Counseling Rooms” and a “Hotto Station” in Tomioka Town wereopened in order to increase understanding about decontamination work by providing information on thepresent status of decontamination and dialogue with landowners and residents.
Besides providing decontamination information, they also provided space for residents to rest when they
temporarily returned home to observe decontamination work. Also, local residents worked here as advisors,
so the venues were a space for residents to interact. Also, the spaces were used for exhibitions ofphotographic works.

Improving the behavior of workers
There were instances of staff from decontamination contractors taking turns once a week to stand at
major intersections or in front of convenience stores to monitor workers’ in-store and road manners. For
example, they would politely remind workers not to dispose of gloves and masks used for decontamination
work in the store trash bins, or not to enter stores wearing muddy boots, or to avoid speaking loudly inside
the store.
Workers were also encouraged to have good manners in the community, being polite and greeting local
residents.
Measures to prevent traffic congestion
In Special Decontamination Areas, there are few lodgings near the work sites, so many workers
commuted from the surrounding region. Also, due to the earthquake disaster and evacuation orders, traffic
congestion sometimes occurred due to the limited choices in passable roads. For this reason, efforts weremade by arranging for commuting buses, offsetting the morning assembly times and locations, and making
starting times and working hours earlier, etc.
Also, since the main roads for work commuting were the same roads used to bring children to elementary
schools during rush hours, various actions were taken to avoid accidents involving children, such as261

dispatching traffic guides, and in some cases having decontamination contractor staff monitoring roads forexcessive speed of commuting vehicles during the hours children go to or return from school, etc.

Credit: Taisei Corporation
Outreach activities at convenience stores

Credit: Taisei Corporation
Traffic guides and reminders

Figure 4-61 Examples of activities for good community relations
Accidents and Problems

There were 1,786 cases of accidents over five years of decontamination work in Special
Decontamination Areas, and the highest year was 2015 (727 cases). Three fatal accidents occurred. In thefall of 2016, a series of heavy machinery accidents occurred, including fatalities, so on November 4,
2016, the Fukushima Office for Environmental Restoration issued a warning to the contractor s, and on
November 21 urgently summoned representatives of the contractors and ordered more thorough safetymeasures and on-site management. On November 30, the Japan Construction Federation (Special
Committee for Electric Power Countermeasures) also made similar requests. After that, the contractors
carried out urgent patrols.
Also, there were many cases of insect bites and heat stroke.
Table 4-13 Types of incidents (Special Decontamination Areas)
Crash, Fall, Pinned, Flying Structure
Animal Cut, Insect
Year
Traffic
fall trip
caught object collapse
bite scrape bite
1
12
2(1)
0
0
9
0
5
7
2012

As of March, 2017
Heat property
Fire Other
stroke
loss

Total

3

0

0

3

42(1)

2013

8

29

12(1)

3

1

34

1

22

38

29

6

0

16

199(1)

2014

6

66

24

12

0

83

0

36

42

44

80

1

30

424

2015

7

54

33

14

1

95

4

52

151

179

63

3

71

727

2016

2

24

19(1)

12

2

112

7

20

77

54

34

1

30

394(1)

Total

24

185

90(3)

41

4

333

12

135

315

309

183

5

150

( ) are fatal accidents.

262

1,786
(3)

Response to improper decontamination
On January 4, 2013, media reported that there had been substandard decontamination work at some sites,so MOE established the “Headquarters for Promoting Proper Decontamination ,” and conducted a surveyof the cases cited. It concluded that many cases could not be determined to be improper decontamination,
but in order to eliminate doubts about decontamination work, on January 18, 2013, MOE announced aProgram for Proper Decontamination with three components to “strengthen the structures of MOE”:“thorough enforcement of contractor responsibilities,” “creation of a wide range of management
mechanisms” including effective independent monitoring, and the establishment of a 110 hotline (callcenter) to report improper decontamination, etc., in an effort to eradicate improper decontamination andrestore the confidence of residents.
Thereafter, the expert Committee to Promote Proper Decontamination met on March 18, 2013, andconfirmed four cases of improper decontamination so far in Special Decontamination Areas and two cases
in Intensive Contamination Survey Areas, for a total of six cases reported, and response actions were taken.
Table 4-14 Implementation status of Committee to Promote Proper Decontamination
Meeting
Date
Venue
Main agenda items
No.
3/18/2013
Koku Kaikan,
1. Establishment of Committee to Promote Proper
Room B101
Decontamination
1
2. Efforts to promote proper decontamination so far
3. Other
7/8/1013
Koku Kaikan,
1. Establishment of Committee to Promote Proper
Room 201
Decontamination
2
2. Efforts to promote proper decontamination so far
3. Other
11/18/2013
MOE Meeting
1. Recent decontamination trends
3
Room 1
2. Efforts to promote proper decontamination so far
3. Other
4/22/2015
Central Gov’t
1. Status of progress of decontamination
Bldg. No. 4
2. Status of Implementation of Program for Proper
4
Building, 12F,
Decontamination
Special Meeting
3. Recent cases and efforts
Room 1214
4. Other
5/24/2016
Koku Kaikan,
1. Status of implementation of Program for Proper
Room 123
Decontamination
5
2. Efforts to improve the reliability ofdecontamination work and plans for this fiscal year
3. Other
6/28/2017
Koku Kaikan,
1. Status of progress of decontamination
Room 201
2. Status of implementation of Program for Proper
Decontamination
6
3. Recent cases and efforts
4. Improving trust in decontamination · Status of
implementation of community contribution action
plan

263

<Members of Committee for Proper Decontamination>
Name
Masaaki Hosomi
Masashi Kamon
Hiroshi Suzuki
Yukimi Sekiguchi
Tetsuya Hasegawa
Junichi Ogata(Titles omitted)

Affiliation
Professor, Graduate School, Tokyo University of Agriculture and Technology
President, National Institute of Technology, Kagawa College, Professor
Emeritus, Kyoto University
Professor Emeritus, Fukushima University
Certified Public Accountant, Tax Accountant
Manager, Social Affairs and Environment Department, Fukushima Prefecture(1st - 4th meetings)
Manager, Social Affairs and Environment Department, Fukushima Prefecture(5th meeting onward)

Table 4-15 Case list of improper decontamination (Special Decontamination Areas)
When
Summary
discovered
Dec 2012
Water from highpressure washing
scattered duringdecontamination of averanda of a privatehouse in Shimokobana
work area of Naraha
Town

Dec 2012

Feb 2015

Water from highpressure wash flowed
into roadside gutter
during decontaminationin parking lot in front of
the Nimaibashi post
office, Iitate Village
Decontamination waste
was illegally buried inforest in Minamisoma
City

Response by MOE, etc.
· Vice Minister of theEnvironment, Parliamentary
Secretary of the Environment,
Director of the Fukushima
Office for Environmental
Restoration and supervisorypersonnel confirm the site
· Instructed workers to prioritize
decontamination and investigate
locations where water scattered,routes of wastewater flows, andpresence of well contamination

Measures to prevent
recurrence· Confirmed no difference
in radiation dose before
and after drainage flow,
confirming thatradioactive substances
containing cesium arebelow the detection limit
in well water· Received newspaper coverageand checked the situation withthe contractor (joint venture)· Instruct decontamination ofaffected locations· Decontamination of
public roadside guttersfrom which pressure washwater spread out wasdone according to
specifications· Contractor was instructed totake action to prevent
recurrence· Strengthened oversight system
by increasing number ofsupervisors· Further education to
improve handling ofwaste· Ensure that primarycontractor supervisor
checks before work isdone, gives instructions,and confirms work inprogress on site
· Strengthening patrols toprevent improper
decontamination

264

Mar 2015

Soil, etc., generated bydecontamination of
Minamisoma City andgeneral waste mixed into
flexible container· Inspection of contents of large ·Thorough separation of
soil
contents of large soils· Instruct the contractor tothoroughly separate the contents

Table 4-16 Case list of improper decontamination (Intensive Contamination Survey Areas)
When
Summary
Response by MOE, etc.
discovered
May 2014 Removed soil from ○ MOE
decontamination work · In the name of Director’s office
at one private homefor decontamination, guidance
illegally buried on
documents were issued toproperty near anotherrelevant local governments to
private home in Tamura
ensure “thorough management ofCity
removedsoil
fromdecontamination
and
other
measures”· In the name of the director of the
Fukushima
OfficeforEnvironmental
Restoration
documents were sent to themayor of Tamura City instructing
the city “thoroughly manage
removed soil from measures suchas decontamination,” and toreport how it happened this timeandspecificrecurrence
prevention measures, etc.
Dec 2015
Illegal dumping of ○ MOE
removed soil from · Requested report of improved
Koriyama City found on
management and recurrence
streets of Iwaki City
prevention
measuresin
Koriyama City
· Written request made to eachmunicipality to improve proper
management of removed soil etc.

265

Measures to prevent
recurrence· Instructed to collectburied container bags
· In the name of themayor, issued guidance
documents to primarycontractor
totakemeasures to prevent
recurrence,
implemented patrols bycity staff etc., andstrengthened guidanceon inspections, etc.
· Notified of suspension(3 months)○ Koriyama City
· Sent written instruction
to each decontamination
contractor to prevent
improperdecontamination work
· Implemented training
on proper handling ofremoved soil, etc., foreach primary contractor

Regulatory compliance and proper decontamination
Other than “improper decontamination,” “incidents of legal compliance at with regard to project
implementation,” and “cases that seemed to be inadequate regarding securing local sense of safety andbuilding trust” were reported to the Committee to Promote Proper Decontamination and dealt with.
In March 2017, an official working at the Fukushima Office for Environmental Restoration was arrested(and later prosecuted) on bribery charges for the illegal act of accepting bribes, after it was discovered thatthe official had received funds for accommodation expenses totaling an equivalent of hundreds of thousandsof yen in 2015 and 2016 from a specific business that expected to be recommended as a subcontractor fordecontamination work in Namie Town. In response, the following actions were taken: (1) giving personnel
instruction, (2) strengthening of ethics training as public servants for all personnel at the Fukushima Officefor Environmental Restoration, (3) thorough efforts to ensure civil servant ethics among supervisorypersonnel, (4) prohibition at the Fukushima Office for Environmental Restoration on actions including
wining and dining with contractors, (5) launch of a “contractor direct dial” phone line to receive problem
reports from hired contractors, (6) notifications to contractors, etc.
In May 2017, it was discovered that some subcontractors had overcharged in their invoicing fordecontamination work ordered by Fukushima City, having falsely represented regular forest
decontamination work as bamboo forest decontamination at a higher unit price. Fukushima City as thecontract issuer ordered the primary contractor to return the funds that had been paid excessively, andimposed administrative sanctions.
In June, 2017, it was discovered (later prosecuted) that an employee of a primary contractor that was
engaged in decontamination work for Tamura City had altered receipts for accommodation expenses, andimproperly received reimbursements based on the receipts. In response, MOE (1) imposed administrative
sanctions on the primary contractor, (2) investigated the decontamination work that had been ordered by
MOE and found that there had been no fraud such as inflated charges due to tampering of receipts, but
discovered accounting errors and announced the findings, and (3) repeated its requests that the constructionindustry reinforce its corporate governance and bolster efforts to ensure compliance with laws andregulations.
In addition to these cases, other instances of improprieties have occurred, such as murder bydecontamination workers, the involvement of antisocial elements, and traffic accidents, etc. Such incidents
diminish trust in the decontamination work, so MOE has been working to ensure that there are systems inplace among work issuers and contractors for the proper execution of work.

266

Points of Promotion Program for Proper Decontamination
Countermeasures for Improper Decontamination
Thorough implementation
management by business
operator・Establish management
structure・Implement strict
disposal punishment
・Sudden inspection
・Promotion Committee

Insufficient ofmanagement system forprevention of improper
activity

Construction of a wide
management mechanism
・Collaboration withlocal governments
・Providing information
to residents
・Effective monitoringby third parties

Strengthening the structureof MOE・Enhance monitoring
system(Increase staff)・New reporting system
for inappropriate
decontamination.
・Centralize reporting

Insufficient check by local
communities and third
party

Insufficient management
system of MOE

Improved reliability for Decontamination activity and Further acceleration of Decontamination work
Figure 4-62 Main points of Program for Proper Decontamination

Model Projects
Municipal projects
Government projects

Number of reports

2013

2014

2015

2016

2017

* Numbers include reports received by the 110 hotline (call center and website) for reporting of improper
decontamination, as well as the Fukushima Office for Environmental Restoration and the Decontamination
Information Plaza.
Figure 4-63 Number of reports on improper decontamination
Source: Documents from “Committee to Promote Proper Decontamination” (sixth meeting)267

Full-scale decontamination began in July 2012, and on October 4 the Koriyama Labor Standards
Inspection Office issued its first recommendation for corrective actions to contractors who had
implemented decontamination work in Tamura City.
The recommendations covered cases of failure to survey legally required parameters at work sites before
decontamination work (average air dose rates, values of radioactive concentrations such as contaminatedsoil, etc., to be decontaminated), and failure to use effective respiratory protection such as dust masks.
In response to the recommendations for corrective actions, there was consultation among the Fukushima
Office for Environmental Restoration, the Koriyama Labor Standards Inspection Office, and thedecontamination contractors. Regarding the measurement of doses, if a survey of dose, etc., is conductedin accordance with the Ionizing Radiation Ordinance for Decontamination, time and costs are incurred, so
it was deemed that the minimum dose requiring protection (2.5 μ ㏜/h) was exceeded, so the use of theminimum protective equipment (surgical mask) was required. Regarding protective equipment, in the caseof working in dust under high doses, high-performance protective equipment (dust masks), etc., are to be
used.
Regarding special work allowances, wage payments are specified in the Common Specifications for
Decontamination and Other Work ordered by MOE, and primary contractors are obliged to provide
payments of the full amounts to target workers, and to verify the status of payment. Also, in order toconfirm the status of payment of special work allowances to workers, primary contractors are required topresent to MOE ledgers of wages paid. In addition, MOE is requesting the Japan Construction Federationand the Associated General Constructors of Japan to circulate information to raise awareness that any
increase in the unit price for design work is expected to increase the wages for skilled workers, in order toencourage young people to enter the decontamination business through improved treatment.

Table 4-17 Statistics for supervisory guidance from the Fukushima Labor Bureau (2013-2016)
Year
2013
2014
2015
2016
Item
Number of companies
subjected to supervision
Number of violatingcompanies
Violation rate (%)
Number of violations, ofwhich:
Working conditions
Safety and healthmatters

1,047

1,152

1,299

1,020

709

774

839

586

67.7％

67.2％

64.6％

57.5％

1,784

1,697

1,586

982

1,210

898

691

485

574

799

895

497

Source: Supervisory guidance results for decontamination contractors, Fukushima Labor Bureau, MHLW(Ministry of Health, Labor and Welfare)268

Table 4-18 Main violation details (2013-2016)
Violations of Industrial Safety and Health Act and Ionizing Radiation Ordinance for Decontamination
Ionizing
Radiation
Ordinance
The Act
Contents
2013
2014
2015
2016
for
Decontamination
ArticleArticle 5 Dose measurement
31
97
92
44
22
Article 7 Preliminary survey
64
145
122
101
Article 9 Work captain
8
3
24
13
ArticleContamination inspection of
22
18
18
4
14
workers exiting work sites
ArticleContamination inspection of15
items carried out of work
5
12
15
0
sites
ArticleUse of protective gear
44
38
47
17
16
ArticleArticleImplementation of special
35
5
6
1
59
19
education
ArticleArticleImplementation of special
23
26
18
4
66
20
health checkup
ArticleReportingon
Article24
decontamination ionization
－
75
87
107
100
health check results
OthersProhibition of smoking etc.
－
45
41
11
Violations of Industrial Safety and Health Act and Others
The Act
Article20

Article31

Ordinance
Article 155
Article 158, 164others
Article 519, 563
otherArticles 653,
655

Contents
Work plan for vehicles,
construction equipment
Work safety of vehicles,
construction equipment
Measures to prevent
falls from high places,
scaffolds
Guidancefromprimary contractors to
subcontractors
Regularvoluntary
inspectionsofvehicles, construction
equipment

2013

2014

2015

2016

－

8

11

8

－

28

29

13

－

22

19

6

－

7

13

5

－

146

182

108

－

9

12

8

Article29-

Article45

Article 167, 1692

Article23

Article 540

Safety routes

－

4

4

4

Others

Duties, etc., of persons
responsible for safety
and health

－

111

155

43

269

Violations of Labor Standards Act
Labor
Contents
2013
2014
2015
2016
Act
Article Explanation of working conditions
201
121
102
46
15
Article Payment of regular wages ※
133
88
56
36
24
Deduction from wages of(Majorfees(memberships,
categories) accommodations, food, etc.)
68
54
33
24
without conclusion of labormanagement agreement
Wage non-payment for timerequired for special medical
35
25
16
6
examination and internalradiation measurement
Article Payment of leave allowance
8
31
4
1
26
Article Working hours
174
145
93
77
32
Article Payment of bonus wages
266
238
219
159
37
Article Formulation
andnotification
of
－
61
52
23
89
employment rules
Article Creation of worker register
121
56
36
29
107
Section Creation of wage ledger
213
111
90
86
108
Other
Notificationofdormitoryrules,
notification of installation of dormitory,
－
47
39
28
etc.
Source: Supervisory guidance results for decontamination contractors, Fukushima Labor Bureau, MHLW270

In the case of torrential rains in the Kanto-Tohoku region in September 2015, heavy rain fell especiallyon the Nakadori region in Special Decontamination Areas, and Iitate Village also received 382 mm overthe course of three days from September 9 to 11 September (nearly twice the average September rainfallof 205 mm).
Due to this heavy rain, the major rivers in the village flooded, 448 large container bags that had been
temporarily placed at decontamination sites on agricultural land along the river flowed out to the river, but
443 bags were collected. The remaining five bags were inaccessible in ravines that were difficult to reach,so after a review of possible methods to collect them safely, they were all retrieved on May 16, 2016.
Bottom sediments of rivers and lakes were monitored in the area downstream of the spill, and it was foundthat concentrations of radioactive cesium were within or below the range of concentrations found inmonitoring before the heavy rainfall.
To prevent reoccurrence, as a rule it is important not to place container bags in any flood hazard area, tominimize the length of temporary placement, to strengthen communication systems, and to continuously
have a tally of container bags at decontamination work sites. In the event of heavy rain or flooding, it was
decided to carry out emergency measures such as using rope to tie together any container bags temporarily
placed at a decontamination site and secure them to heavy equipment, etc.
Also, the Fukushima Office for Environmental Restoration was informed that five workers did not comeback on the evening of September 17 when they were in a steep ravine trying to retrieve container bags
that had been washed away. The fire brigade that had received a call from the contractor abandoned its
search at 8:27 p.m. on September 17. With cooperation from Fukushima Prefecture, Fukushima Prefecture
Police Headquarters, Soma Fire Department Headquarters, and the Ground Self Defense Force, the search
was resumed from 6:00 a.m. the following morning, and it was confirmed that all members were safe by
9:44 a.m. MOE issued guidance stating that in the event of a disaster, it is crucial to recognize that thepriority should be given to ensuring the safety of human lives, including those of third parties anddecontamination workers, and that contractors should have disaster prevention systems in place.

271

Accidents, improper decontamination, etc., occurred in the context of education being provided forworkers who numbered up to 20,000 persons a day at one site. As mentioned above, decontamination
contractors conduct education and management in various ways starting with the beginning of a project,but in order to prevent accidents and improper decontamination, they continue with thorough efforts toimprove management systems and provide education, etc.
① Development of work management systems· The system was developed based on the assignment of one decontaminating contractor staff member
and one primary cooperating company staff member to each 30 decontamination workers.
· To confirm that work was being performed properly, they would conduct day-to-day visits to the sites
to observe groups based on type of work, and also conduct group-by-group quality patrols (quality
checks of work standards, ensuring there was no illegal dumping, etc.) and safety patrols (safety checksof work standards and confirmation of compliance with related laws and regulations).
② Education of staff and workers (activation of communication)· For decontamination contractor personnel as well as the workers in cooperating companies, efforts
were made for educated and awareness raising about the following points in order to ensure thoroughquality control.
<Decontamination contractors>· Instruct cooperating companies to ensure that workers do not engage in any work that is not incompliance with work standards, or work that can lead to misunderstandings· By rereading the work standards reconfirm the understanding of not only workers but also the staff
themselves, and work to make improvements to work standards.
· Make efforts to better communicate with cooperating companies and workers in order to identify
problems in a timely manner.
<Cooperating companies and workers>· Educate workers so that they do not engage in work that does not meet standards or conduct workthat can lead to misunderstandings.
· If in doubt, consult with the joint venture at any time.
· Establish a quality control “refuge” (consultation system) for workers to report to the joint venture(primary contractor) cases in which they observe or are being forced to do substandard work, anddisplay posters announcing the system in rest areas and offices, etc.

272