BASIC STUDY ON METHODOLOGY OF SELECTION OF A SITE SUITABLE FORLANDFILL TAKING ENVIRONMENTAL RISKS INTO CONSIDERATION

K. Nakaishi1,

F. Igari2,

K. Hayashi3,

Y. Hamada4,

S. Yokota5,

T. Furuichi6, and M.Hanashima6

1 Environmental Excellent Engineering Co., Ltd.
2-17-22 Takada, Toshima-Ku, Tokyo 171-0033, Japan
2 Oyo Corporation
2-61-5 Kita-ku, Toro-cho, Saitama-shi, Saitama 331-8688, Japan
3 Maeda Corporation
J.CITY14F, 5-8 Takamatsu, Nerima-ku, Tokyo 179-8903, Japan
4 TOWA Technology Corp.
10-2, Nihonbashihakozakicyo, Cyuoh-ku, Tokyo 103-0015, Japan
5 JDC Corporation
4036-1,Nakatsu,Aikawa-machi,Aikoh-gun,Kanagawa-pref,243-0303,Japan
6 The landfill systems & technologies research association of Japan (LSA, NPO)
401 Chateau Takanawa, 3-23-14 Takanawa, Minato-ku, Tokyo 108-0074, Japan

ABSTRACTThis study examined the methodology of selection of a site suitable for landfill taking environmental risks into
consideration as a method for construction of landfills that can be accepted by the local residents, aiming to realize
suitable and smooth construction of landfills. Then, we presented the methodology of selection and assessment of asuitable site for landfill, which is the result of this study, through a questionnaire for surveying consciousness ofresidents for landfills to investigate the level of the residents interest on this matter. As for the environmental risks
which includes various risks with regard to landfills, we selected the risk of leak of leachate from landfills(hereafter called “the environmental risk“) as a subject of the study. As an index of the environmental risk, we
proposed the use of “leak outflow time (timeｔ0)” that expresses the leak retaining capability of a specific ground(site), and reviewed a system that performs the management of the environmental risk (minimization of the risk) of
any candidate site by using the index. This study demonstrated by using the simulation that the abovementioned
system is effective to some extent, and from the result of the questionnaire sent out to the residents, that the system
can be a means effective for building consensus of the local residents.

Keywords: Environmental Risk, Risk Management, Selection (Evaluation) of a Site Suitable for Landfill

1INTRODUCTION

leak of leachate. This study especially placed emphasis

Making a selection of a landfill site is a big challenge

on minimizing the effects (damages) (bringing the

because, in many cases, the neighboring residents

damages to zero as near as possible) in case of

oppose the plan due to the deep-seated distrust of theaccidental leak of leachate.

leakage of polluted liquid from the site. To deal withthis difficult problem, we considered to examine an

Methodologies of environmental risk management

introduction of the idea of the environmental riskin selecting suitable landfill site (methodology for

management in the phase of selection of a site suitable

minimizing environmental risk, and methodology

for landfill to provide answers to their question “Whyfor selecting suitable landfill site)

this site is selected for landfill?” by improving their

As for minimizing the environmental risk of aunderstanding of the safety of the landfill and selecting

proposed landfill site, we proposed the use of “leaka site that can minimize the environmental risk

outflow time (timeｔ0)” as shown below as an index

efficiently. Based on the above matter, this study

for estimating the leak retaining capability of a

examined the methodology of selection of a suitablespecific ground (site), and thus, examined to perform

site for landfills that considers to minimize thethe risk management by using this index.

environmental risks of the landfills so that the project“Leak outflow time (time ｔ0)”＝Period of time fromis accepted by the residents, aiming to realize fair andthe geomembrane is damaged to the moment thesmooth construction of landfills. We also sent out

hazardous substance contained in the leak of leachatequestionnaires to the residents, in which we describedreaches the environmental limit at the border line of

the methodology of selection of a suitable landfill site

the landfill (Refer to Figure 1.) …… (1)that is the achievement of this study, to investigate

Based on the above index, a landfill is estimated totheir level of interest on this matter, and the results arehave low “environmental risk” as the leak outflow

presented here.

time from the damage of geomembrane to the borderof the site is longer, meaning that the leak can be

DETAILS OF STUDY

retained, or it is estimated to have high “environmental

This study was made on the risk of leak of leachaterisk” if the time is shorter, meaning that the leakfrom landfills, which is one of the environmental risks

cannot be retained. Therefore, the environmental riskthat are included in various risks involved in theis given conceptually by the following formula.

landfills. This subject was selected for our study
because the risk is assumed to cause the biggest

Environmental Risks＝1/ｔ0 …… (2)anxiety related to the safety of the landfills in all theenvironmental risks of landfills (hereafter, the risk of

Byleak of leachate from landfills is referred to as “theminimization standard of the time ｔ0 (time T0c) as “aenvironmental risk”. The environmental risk covers

time needed to take measures for prevention of

the probability of leak of leachate from a landfill anddiffusion of a leak of leachate to peripheral area inthe magnitude of effects (damages) produced by thecase of leak”, it is possible to conduct the management2

settingthedefinition

of

the

step-by-step

of leak as a preventive measure by using thestep-by-step standard as a bench mark. As a result, a
landfill system that is capable of achieving an ultimate
standard value (ｔ0＝∞) is planned out. This meansthat selection of a site suitable for a landfill is made by
implementing measure for prevention of an accidental
leak (environmental risk nearly equal to zero)
assuming that it can ensure prevention of effects

Ｔ０c1 is a time needed for preparation of a full-scale work in(damages) on the peripheral environment with infinite

step 2 in case of accidental leak of leachate. Therefore, if ittime t0.

is decided that the time of step 0 is Ｔ０＜Ｔ０c1, an

Figures 2 to 5 show concrete risk management process

improvement of the system assuming that a corrective workwith detailed description of t０ and T０c .

for making Ｔ０≧Ｔ０c1 (constructing a third seepage control

For a candidate landfill site, t０ that is defined as a timesystem) is to be made to secure the period needed for thethe concentration of pollutant measured at the borderwork to prevent the effect of the leak from reaching outside

line of the site reaches the environmental standard ofof the border.

the locality is T ０ in the state before a particular

Figure 2

Meaning of time T０ in step 1

preventive measure is taken in that site (Step 0 in
Figure 1). T０c is the minimum standard time of T０,
and it changes as T０c1, T０c2, and T０c3 as the stepadvances.
The meanings of T０c and T０ in individual steps are as
described in the Figures1 to 4 respectively.
Leak outflow time(ｔ0）Ｔ０c2 is a time needed for repairing the seepage control
system on the surface and then cleaning up the ground watercontained in the side after containing the leachate in the site.
Therefore, it is necessary to allocate the cost of accidental
leak prevention work (vertical seepage control system) for
Time T０;Time the concentration of hazardous substances

achieving Ｔ０≧Ｔ０c2 to make the leachate containing

contained in the groundwater and soil from leak of leachate

time longer than the period for repairing the damage andreaches the environmental standard at the border line of acleaning up the liquid.

Figure 3site when no particular preventive work is done (Ｔ０).

Figure 1

Meaning of time T０ in step 0

3

Meaning of time T０ in step 2

Site boundary

Discussion about method of calculation of time ｔ0
and verification of the validity (analysis of groundConstruction period of vertical impervious wall
Landfilled solid waste

water pollution in landfills)
Examination of the method of calculation of the time

Underground stream

parameter (ｔ0) that is proposed in the formula (1) and

Water leakage of leachate(2) as a methodology for environmental risk
Impermeable layer

management and verification of the validity of thisContaminant concentration(Equal to the environmental criteria)

idea were implemented based on the existingＴ０c3 is the time the concentration of hazardous substance atmethodology for simulation of soil and ground water

the border needs to exceed the environmental standard after

pollution, “GETFLOWS”.

the action of step 2 is taken. Therefore, the time is infinite (ＴFigure 5 and Table 1 show the schematic drawing of＝Ｔ０c3＝∞), meaning that the system is designed so thatthe simulated landfill model and set conditions

the concentration of hazardous substance at the border will

respectively.

０

not exceed the environmental standard.

Figure 4

Meaning of time T０ in step 3

50m
1%

Waste disposed
4.0m

1%

1.5m

1%

4.0m

1%

5.0m

1%

Evaluation point A: 10m to border linefrom pumping well
Evaluation point B: 1m to landfill side
評価点Ａ：揚水井から敷地境界側に
10ｍ地点
50ｍ
from impervious
wall
評価点Ｂ：遮水壁から埋立地側に 1m 地点
Evaluation
point
C:
1m
to
borderline
評価点Ｃ：遮水壁から敷地境界側に 1m 地点
from impervious wall
揚水井
Pumpingwellline of site Permeabil(ケース③)(case③) Border
敷地境界線
透水係数 Effective
有効間隙率
coefficie
porosity(cm/sec)

Level of 埋立廃棄物
water in the site
m 1.0 m
▽ 場内水位(常時 1.0m） 1.0ｍ(constant
at 10m)
浸出水の漏水Leakof leachate

Lm-3
Lm(ﾛｰﾑ層)(loam
layer) 1.0 ×10
評価点Ｂ Dc (粘土層)▽
1.0 ×10 - 5
1 (clay)
評価点Ａ● ● ●評価点Ｃ
Dg 1(砂礫層)(gravel) 1.0 ×10- 3

Flow ofgroundwater
地下水の流れImpervious遮水壁
wall(ケース②,③)(cases ②
and ③)

Dc 2(粘土層)(clay)

1.0 ×10 - 6

Figure 5 Setting of simulated landfill model
Table 1 Simulation conditions
Item

Simulation conditions

Size of leaking damage

10cm×20cm

Assumed pollutants and their

Chlorine ion, concentration at pollutant source；10,000mg/L,

concentration

background concentration；10mg/L

Permeability

coefficient,

Ｋｈ/Ｋｖ＝2.0

horizontal to vertical ratio

4

0.22
0.03

0.16

0.03

to

verifytheenvironmental

10000

risk
Concentration of pollution (ppm)
汚染濃度（ppm）

Moreover,minimization effect (effect of extension of time ｔ0)of the leachate leak prevention work, the simulation
was made for the following two cases. An impervious
wall is installed when the concentration of the chlorine
ion at the border 50m downstream of the leaking point
reaches 200ppm that is the standard value for drinkingb) Preventive work by using impervious wall andrepairing leak (Evaluation T0 with respect to Tc2)
Preventive work by using impervious wall,

10

1

20

40
60
80
経過時間（日）Elapsedtime (days)

100

120

the chlorine ion concentration exceeded 200ppm atconcentration of pollution reaches 200ppm, thethe border of the site that is 50m from the damaged

measurements shown in Figures 6 and 7 werepoint. This number of days is long enough for

obtained.

completing the construction of the impervious wall

Concentration of pollution (ppm)

after a leak of leachate actually occurred (the10000construction period Ｔ 0 ｃ = approx. 300 days).

Damage10cm x 20cm矩20cm, rectangular
破損箇所10cm×形

Thus, it is confirmed that the primary action of the

1000(参考) (reference)
1cm x2cm矩2cm, 形
rectangular
破Damage
損箇所1cm×environmentalrisk

management

with

the

construction of the impervious wall under the

850日
経過後にof pollution reached
Concentration
200ppm after
200ppmに到達850 days.

0.1

評価点C（揚水有）Evaluation point C
評価点C（揚水有）(with pumping)(Ｔ0≒850 days) from the day the leak began whenoccurrence of leak of leachate to the moment the1

評価点B（揚水有）a) As shown in Figure 6, it was at about 850th day

As a result of the simulation of the elapsed time from10

評価点A（揚水有）above results.

with respect to Tc3)

汚染濃度（ppm）

評価点C

point B
Evaluation
評価点B Evaluation
評価点B（揚水有）(with pumping)
point B
Evaluation
評価点C
point CThe following knowledge was obtained based on thepumping water and repairing leak (Evaluation T0

Concentration of pollution (ppm)

評価点B

100

Figure7 Change of Chlorine ion concentration in andout of impervious wall
(Evaluation points A to C, cases of b) and c)with protective work)

Tc1)

100

Evaluation point A
評価点A（揚水有）(withpumping)
評価点A

0

No preventive work (Evaluation T0 with respect to

c)

1000

0.1

water.
a)

Evaluation
評価点A
point
A

ground layer conditions that were set for this site iseffective.

Damage10cm20cm矩x
破損箇所10cm×形
20cm, rectangularb) As shown in Figure 7, the concentration reduced up

Damage1cm2cm矩x 2cm,
破損箇所1cm×形

0.01

rectangular

to 50% of the maximum after approximately 2

0.001
0

1000

2000

3000
4000
経過時
間（日
）
Elapsedtime(days)

5000

6000

weeks from the beginning of the pumping at the
upstream side. When the cleaning of undergroundFigure 6 Change of Chlorine ion concentration at theborder of the site
(Top of gravel layer, case with no protective work)

water within the site is performed, it can be realized
by continuing the pumping. With this preventive
action, the parameter time Ｔ0 becomes infinitive,
meaning that the action is effective for minimizing
the environmental risk.

5Results of the questionnaire

Figures 9 and 10 show the results. These graphs show

We had a questionnaire to the residents around athat approximately 90% of the residents who

landfillof

responded to the questionnaire made a response withinvestigating what is the perception they have in terms

the answer “I would like to hear detailed explanationsof the landfill and what is their understanding of theabout the matter”, and approximately 75% of themfacility. The outline of the questionnaire is described inmade a response that they wish to hear especiallythe Figure 8 and Table 2.

about “how the operator take actions in case of leak ofthroughLevelofinternetforinterestonthepurposeofleachate”. This result shows that “the methodologies

environmental risk management in selecting siteof environmental risk management in selecting site

suitable for landfill

suitable for landfill” that are described in this paper

As one of the questions of the abovementioned

can be one of the systems that are effective forquestionnaire,obtaining agreement on the landfill project from the

3-2

we

presented

methodology“methodologies

oflocal residents.

environmental risk management in selecting site
suitable for landfill” that are shown in Figures 1 to 4 toinvestigate the level of interest of the residents on thismatter.
No. of questions:about 15
Requestingquestionnaire
System planning andresearch group

Payinginvestigation
cost

Committee of evaluation
and research ofenvironmental risks oflandfill

Results ofquestionnaire

Company implementing
questionnaire
・Preparing the form・Preparing the form fordisplay・Aggregation of data
・Processing data (crosstabulation, etc.)
・Preparing simple rep ort

Transmitting
questionnaire

Transmitting
responses to

Itemquestionnaire

Researchmonitors[Extractable attributeitems]
Age, sex,
occup ation, marriage
status, prefecture ofresidence

Persons surveyed
No. of samples
No. (exp
ofected):valid
1000
residents
responses
Figure 8 Outline of the questionnaire

Item
Persons surveyed
No.
of
valid
responses
Sampling method
Termof
implementation
Methodofinvestigation
District covered
Principal questions

Descript

General residents (20 years old and older)1,183 (This is the number of samples that
reliable to some extent from population acroolder)
Sampling method
Random sampling from research monitors w
Table 2 Outline of implementation of internet questionnaire
site
Term
of from February 15 to 17, 2006 (three days)
Description
implementation
General residents (20 years old and older)
Methodof forWeb
questionnairethrough internet
1,183 (This is the number of samples
that is required
obtaining
information
investigation
reliable to some extent from population across the country who are 20 years old andDistrict covered
Across the country (research monitors)
older)
Principal
questions①Necessityof landfills,
Random sampling from research monitors who are registeredin the internet
portal ②Anxieties over lan③Timeof
participationin the landfill pro
site
stressedfrom February 15 to 17, 2006 (three days)⑤Information about landfill that are required⑥Imageof landfill that the resident wishes to
Web questionnaire through internet

Across the country (research monitors)①Necessity of landfills, ②Anxieties over landfill③Time of participation in the landfill project, ④stressed⑤Information about landfill that are required,⑥Image of landfill that the resident wishes to have.

6

Environmental actions to be

I do not like to hear
explanations
about話を詳しく聞いてみたい
the matter.
話を聞きたくない

Cost of construction of landfillthat uses this system

Others

0.95%
1.80%

22.71%

I would like to heardetailed
explanations

10.65%

about the matter.

Figure 10

Figure 9 Level of interest on the methodologies of

実際に浸出水が漏れた場合の対応方法（汚染が広がる速さ、浄化方法等）についてActions
to be taken in case
本仕組みを持ったごみの処分場のleakof leachate actually
建設費についてoccurred(speedofその他
dispersionof pollution, andhow to clean it, etc.)

74.55%

89.35%

Principles
and fundamental
基本的な原理および考え方についてthoughts
ofthemethodology

Matters the residents wish to hear thedetails when a risk management methodology isenvironmental risk management

adopteCONCLUSIONSThe effectivenesses of the parameter time ｔ 0

On the other hand, since the above conclusions depend

that is proposed as a methodology of environmental

only on the analytical model, it is necessary torisk management are expected as follows.

demonstrate and repeatability of the matter. Therefore,

Parameter time ｔ 0 can be obtained throughas a future issues, it is necessary to improve thecalculation.

appropriateness of the setting conditions and accuracya)The results of the calculation are valid unless it isof the results while carrying out technical validations

performed without deviating generally acceptedof the matter.

theories.
b) From the effectivenesses described in a) and b), itc)

ACKNOWLEDGMENT

can be said that the parameter can be used forThis study is an achievement of the study on the

management of risks caused by the leak of

methodology of selection of site suitable for landfill

leachate.

takingFrom the results of the questionnaire to the

conducted by the System planning and research groupresidents, the methodologies of the environmental

in its “voluntary research project” that is a part ofrisk management that are proposed in this paper

activities

can be an effective means for obtaining agreement

Technologies Research Association of Japan (LSA)”.

on the construction of landfills from the local
residents.

7

environmental

of

the

risks

NPO

into

“Landfillconsideration

Systems&