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CE 199 – Undergraduate Research Project 19 March 2010

Final Presentation Geotechnical Engineering Group

CHARACTERIZATION AND VIABILITY OF CLAY SOILS FROM

METRO MANILA AS LANDFILL LINERS

DEXTER V. PERDON

RALPH O. ACEBEDO

Undergraduate Students, B.S. Civil Engineering Program

Institute of Civil Engineering, University of the Philippines Diliman

E-mail: ralphacebedo@yahoo.com / dexter_perdon@yahoo.com

Adviser:

Dr. Mark Albert Zarco

Geotechnical Group Head,

Institute of Civil Engineering, University of the Philippines Diliman

Abstract: Clay samples from five different locations were investigated for their viability as part of a landfill lining. The soil

samples were extracted from an ongoing foundation construction in Fortune, Marikina; Taft, Manila; Sta Elena, Rizal;

Katipunan and Brgy Ugong, Pasig. The soil samples underwent several soil tests to determine its geotechnical,

physiochemical and geomechanical properties. The data obtained were then compared to standard design criteria for landfill

liners. These standard design criteria were based on the specifications set by the US Environmental Protection Agency (US

EPA), NRA (National Rivers Authority), Republic of the Philippines Republic Act 9003 and the standards suggested by

Amelandu Bagchi on his book Design Construction, and Monitoring of Sanitary Landfill and Qian, Koerner and Gray’s

Geotechnical Aspects of Landfill Design and Construction. Results show that the grayish brown soil sample from Taft

Manila, which has medium plasticity and traces of sand, passed the all design requirements.

1. INTRODUCTION

1.1 Background of the Study

Modern landfills are highly engineered containment

systems, designed to minimize the impact of solid

waste (refuse, trash, and garbage) on the environment

and human health. In modern landfills, the waste is

contained by a liner system. The primary purpose of

the liner system is to isolate the landfill contents from the environment and, therefore, to protect the soil and

ground water from pollution originating in the landfill.

The greatest threat to ground water posed by modern

landfills is leachate. Leachate consists of water and

water-soluble compounds in the refuse that

accumulate as water moves through the landfill. This

water may be from rainfall or from the waste itself.

Leachate may migrate from the landfill and

contaminate soil and ground water, thus presenting a

risk to human and environmental health.

Landfill liners are designed and constructed to create

a barrier between the waste and the environment and

to drain the leachate to collection and treatment

facilities. This is done to prevent the uncontrolled

release of leachate into the environment. Clay soil is

known to be impermeable, play a very important part

in the whole multi barrier liner system.

Clay is a naturally occurring material composed

primarily of fine-grained minerals, which show

plasticity through a variable range of water content, and which can be hardened when dried and/or fired.

Clays are distinguished from other fine-grained soils

by differences in size and/or mineralogy. Silts, which

are fine-grained soils which do not include clay

minerals, tend to have larger particle sizes than clays,

but there is some overlap in both particle size and

other physical properties, and there are many

naturally occurring deposits which include both silts

and clays. The distinction between silt and clay varies

by discipline. Geologists and soil scientists usually

consider the separation to occur at a particle size of

2µm (clays being finer than silts), sedimentologists often use 4-5 μm,

and colloid chemists use 1 μm.

The design and specification of a landfill clay liner

require compromises to be made between the

requirements of low hydraulic conductivity

(permeability), minimal shrinkage during service, and

sufficient ductility to accommodate tensile and shear

strains, which may increase permeability. The

porosity of clay particle should be within 40 – 70%

and permeability (K) value of clay should be less than

10-7 cm/s and so the rate of advection transport through clay is very low. Clay has the property of

swelling, plasticity, cohesion and adhesion. Some

clay soils have the ability to act as membrane that

restricts the passage of charged solutes.

Clay liners are constructed as a simple liner that is

two- to five-feet thick. In composite and double liners,

the compacted clay layers are usually between two-

and five-feet thick, depending on the characteristics

of the underlying geology and the type of liner to be

installed. Regulations specify that the clay used can only allow water to penetrate at a rate of less than 1.2

inches per year. The effectiveness of clay liners can

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be reduced by fractures induced by freeze-thaw

cycles, drying out, and the presence of some

chemicals.

Geologic maps and previous subsurface

investigations show clays dominate Metro Manila soils. The metropolis’ soil profile is typically consists

of loose to firm silty fine sand layer near the surface.

It is underlain by very soft marine clayey silt or silty

clay that usually gets firmer at the bottom. These

materials are in turn underlain by stiff to very stiff

clay; then, by hard clay and silt interspersed with

dense to very dense sand and/or gravel that grade into

the underlying sound bedrock. The thicknesses and

lateral extents of the layers are not predictable.

1.2. Statement of the Problem

During construction projects, road works, installation

of utility cables and similar operations in Metro

Manila, huge volume of soil, mostly clayey soils, are

excavated or stripped from the surface. In some cases,

the excavated soils will be carried off for re-use on

other locations. However, being clayey in nature,

soils from Metro Manila are basically considered as

“waste materials”. These clays can’t be used as filling

materials since clays are among the most reactive

silicates and they affect the engineering behavior of

soil and rock both as materials of construction and as foundation materials. It's typically considered poor

geotechnical engineering practice to use clay as a

foundation material. Most engineers will recommend

to the clay with compacted structural fill.

On the other hand, clay is an excellent lining material

for landfills since it is relatively impermeable.

However, clays in Metro Manila haven’t been

characterized based on its viability as landfill lining.

1.3. Objectives

To determine the geomechanical,

physiochemical and geotechnical properties

of clay soils acquired from some parts in

Metro Manila.

To provide repository of geotechnical data

which can be used for future studies

To find out if the clay soil sample tested is

applicable as landfill lining material.

1.4. Significance of the Study

The importance of conducting this study is that from

geotechnical data obtained, it will serve as a reference

for future subsurface investigations and structural

designs in Metro Manila. This study would also

explore the potential uses of these clay soil which are

otherwise would be waste material for foundation

construction, specifically its viability as a material for

landfill lining.

The utilization of excavated soils from large projects

may be an alternative to expensive and valuable

geotextiles used as liner material. Excavated soils are

generally dumped at the nearest available place,

causing not only several environmental problems but

also loss of valuable earth material. Exploitation of

these materials in pure or stabilized form would

certainly bring forth an opportunity for energy

savings, as well as providing means to protect our natural resources.

1.5. Scope and Limitation

The design and specification of a landfill clay liner

should have low hydraulic conductivity

(permeability), minimal shrinkage during service, and

sufficient ductility to accommodate tensile and shear

strains. This study will focus on the hydraulic

conductivity of the soil sample since permeability is

the most important factor in considering clay as

landfill liners. In addition, for this study, it would be

difficult to test for shrinkage and ductility of the soil

because of limited time and money.

The only design criteria for landfill liner stated on RA

no 9003 is the minimum required permeability of the

clay soil, which is 1x10e-6 cm/sec. Therefore The US

Environmental Protection Agency Landfill Manual

and the National Rivers Authority Landfill Design

Criteria will be consulted for they offer a more

detailed design criteria for landfill clay liner.

The four samples were provided by private drilling

companies and these samples were recovered from various places in Metro Manila. The evaluation of the

soils from Metro Manila is only limited to five places

and these are Fortune Marikina, Brgy Ugong Pasig,

Taft Manila, Katipunan Avenue and Sta Elena

Antipolo Rizal

2. METHODOLOGY

2.1 Soil Acquisition

The soil samples being tested on this research were

excavated from ongoing foundation construction in

five different locations in Metro Manila, and were

considered as construction wastes for it has no longer

use in the construction site. Technically, these soil

samples are considered disturbed samples. When we

say disturbed samples, it is one in which the structure

of the soil has been changed sufficiently that tests of structural properties of the soil will not be

representative of in-situ conditions, and only

properties of the soil grains can be accurately

determined. An undisturbed sample is one where the

condition of the soil in the sample is close enough to

the conditions of the soil in-situ to allow tests of

structural properties of the soil to be used to

approximate the properties of the soil in-situ.

This research used five soil samples and these were

from the following locations. A soil sample excavated

from Sta. Elena Antipolo, Rizal was provided by Philippine GeoAnalytics. Soil samples excavated

from Fortune Marikina, Taft Manila and Brgy Ugong

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Pasig were provided by Ms Edna Mendoza, a

graduate researcher from the National Institute of

Geological Sciences (NIGS). The last sample was

collected by the researchers on an actual site along

Katipunan Avenue in Quezon City.

2.2 Design Requirements of Clay Soil as Landfill

Liner

Good design of a landfill site will prevent, or reduce

as far as possible, negative effects on the environment,

as well as the risks to human health arising from the

landfilling of waste. It is essential that the designer

adopt methods, standards and operational systems

based on best current practice which reflect progress

in management techniques and containment standards.

The design process should be consistent with the need

to protect the environment and human health.

The following are the suitability standards of clay

landfill liner:

2.2.1 United States Environmental Protection

Agency Landfill Manual (US-EPA)

According to them, clays should perform low

permeability which should be less than 1x10-7 cm/s.

This is to minimize the infiltration of leachate and

contaminate ground water. Plasticity Index should be between 10-30%. Particles with diameter of 0.074

mm and less should be more than 30 % of the soil

composition. And lastly, the maximum particle

diameter should be less than 3 inches.

2.2.2 National Rivers Authority (United Kingdom)

Clay liner permeability requirement is the same as the

US EPA standard, which is less than 1x10-7 cm/s.

While the plasticity index and the liquid limit should

be less than 65% and 90% respectively. The NRA

standard requires clay content greater than 10%.

2.2.3 ‘Geotechnical Aspects of Landfill Design and

Construction’ by Qian, Koerner and Gray and

‘Design, Construction and Monitoring of Sanitary

Landfill’ by Amelandu Bagchi

The permeability should be less than 1x10-7 cm/s.

Liquid limit should be greater than 30% and clay

fraction should be greater than 25%. For shrinkage

potential, plasticity index must be between 15 and 50.

Soil particles having less than 0.074mm diameter must be greater than or equal to 50% soil fraction.

And lastly, the minimum requirement for shear

strength must be 200 kPa.

Table 1. Landfill Standards

GALDC &

DMCSL

USEPA

RA 9003

NRA

Hydraulic Conductivity

1.00E-07

1.00E-07

1.00E-06

1.00E-07

(cm/s)

Shrinkage

Plasticity Index

15% - 50%

10% -

30%

<

65%

Other Specifi

cations

Liquid Limit

> 30 <

90%

Passing P200

> 50% >

30%

Clay

Fraction > 20%

>

10%

Max Particle

size

< 3 in

Chemical

Resistance

Cation Exchang

e

Capacity (milliequivalent/1

00g)

>20

2.3 Experimentation

The five soil specimens were analyzed and subjected

to grain size analysis (mechanical and hydrometer

method), Atterberg’s limit test, compaction test,

permeability test, direct shear test and cation

exchange capacity.

The tests were performed by two geotechnical engineering companies and by one government

agency, Philippine Geoanalytics (PGA) for the shear

strength test, while Advanced Geotechnical

Engineering Services (AGES) for the grain size

analysis, atterberg limit test, compaction test and

hydraulic conductivity test. Cation exchange capacity

test was also performed by the Bureau of Soils.

3. RESULTS AND DISCUSSION

The tables below show the data summary of soil

samples from different locations.

Table 2. Data Summary of Soil Sample from Sta.

Elena, Rizal

Specifications

Santa

Elena

Rizal

Hydraulic Conductivity (cm/s) 1.78E-06

Shrinkage Plasticity Index 21%

Other

Specifications

Liquid Limit 50%

Passing P200 67%

Clay Fraction 9%

Max Particle size 0.5 in

Chemical

Resistance

Cation Exchange

Capacity

(milliequivalent/100g)

11.4

Table 3. Data Summary of Soil Sample from Brgy.

Ugong, Pasig

Specifications Ugong

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Pasig

Hydraulic Conductivity (cm/s) 3.22E-06

Shrinkage Plasticity Index 31%

Other

Specifications

Liquid Limit 62%

Passing P200 77%

Clay Fraction 42.10%

Max Particle size 0.375

Chemical

Resistance

Cation Exchange

Capacity

(milliequivalent/100g)

34.9

Table 4. Data Summary of Soil Sample from Taft,

Manila

Specifications Taft

Manila

Hydraulic Conductivity (cm/s) 4.61E-08

Shrinkage Plasticity Index 22%

Other

Specifications

Liquid Limit 44%

Passing P200 69%

Clay Fraction 22.10%

Max Particle size 0.5 in

Chemical

Resistance

Cation Exchange

Capacity

(milliequivalent/100g)

27.9

Table 5. Data Summary of Soil Sample from

Katipunan, Quezon City

Specifications Katipunan

Hydraulic Conductivity (cm/s) 3.17E-07

Shrinkage Plasticity Index 29%

Other

Specifications

Liquid Limit 68%

Passing P200 75%

Clay Fraction 4.14%

Max Particle size 0.5 in

Chemical

Resistance

Cation Exchange

Capacity

(milliequivalent/100g)

41%

Table 6. Data Summary of Soil Sample from

Fortune, Marikina

Specifications Fortune

Marikina

Hydraulic Conductivity (cm/s) 5.70E-07

Shrinkage Plasticity Index 20%

Other

Specifications

Liquid Limit 47%

Passing P200 66%

Clay Fraction 8.02%

Max Particle size 0.5 in

Chemical

Resistance

Cation Exchange

Capacity

(milliequivalent/100g)

24.6

Among the five samples, the sample extracted from

Taft, Manila has the lowest coefficient of permeability, 4.605 x 10-8 cm/s. While the Brgy.

Ugong sample had the highest with a permeability of

3.22 x10-6.

The results of the grain size distribution curve

indicated that the soil sample from Brgy Ugong has

the highest clay content. The Brgy Ugong sample is

about 42.10% clay while the Taft, Fortune, Katipunan

and Sta Elena are 22.10%,8.02% 4.14% and 9.1%

respectively. The maximum particle size of all the

soil samples is 0.5 in. except the Brgy Ugong sample

which has a maximum particle size of 0.375 in.

Table 23 shows the maximum height that the soil can

carry until it fails. By using the strength parameters,

the normal stress is derived. Shear strength should be

200 kPa as prescribed by Qian, Koerner and Gray of

Geotechnical Aspects of Landfill Design and

Construction and Bagchi of Design, Construction and

Monitoring of Sanitary Landfill. Maximum height of

waste material is derived using the equation τ = c + σ

tan Φ, given the specific weight of waste is

approximately equal to 15 kN/m3

Only the Taft Manila soil sample passed all the

standards set by the US EPA, NRA, and Republic Act

9003. It also passed the landfill requirements

suggested by Qian, Koerner, Gray and Bagchi on

their books.

4. CONCLUSION

The study shows the geomechanical, geotechnical

and physiochemical evaluation of different soil

samples from Metro Manila. This includes the permeability test, Atterberg’s tests, sieve analysis,

hydrometer test, direct shear test and lastly the cation

exchange capacity test.

Having a hydraulic conductivity equal to 4.61 x 10-8

cm/s, the Taft soil sample passed the primary

requirement of a landfill liner. This relatively small

value of permeability is very essential to prevent or

minimize leachate leakage. The Taft sample also

exhibits average plasticity index for insignificant

shrinkage and average cation exchange capacity value for chemical absorption. Having these properties, we

can therefore say that out of the five samples, only

Taft clay soil sample is a suitable landfill material.

5. RECOMMENDATION

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The study is only focused on evaluating the soil

samples and assessing if it is usable as landfill liners.

Out of five samples, four didn’t pass the standards.

However there are ways on how to improve the soil’s

properties like by adding more clay or removing

coarse particles through sieving. There are also some studies that adding some amount of gravel would

decrease the permeability of the soil. There should be

a detailed study to determine the qualitative and

quantitative effects of the changes in the properties of

the soil.

6. REFERENCES

1. Qian, Koerner, Gray (2002). Geotechnical

Aspects of Landfill Design and Construction.

Prentice Hall Inc.

2. Bagchi (1989). Design Construction and

Monitoring of Sanitary Landfill. A Wiley

Publication. Chapter 7, liner materials

3. Tan RC (1983). Engineering properties of

Manila subsoils. MSc Thesis, College of

Engineering, University of the Philippines,

Diliman, Quezon City

4. E.P.P. Mendoza (2006). Mineralogical and

geochemical characteristics of volcanic soils in

Metro Manila, Philippines: Influence on geomechanical behaviour. Engineering Geology

Laboratory, National Institute of Geological

Sciences, University of the Philippines-Diliman,

Diliman, Quezon City 1101

5. H. Akgu¨n (2004). Composite landfill liner

design with Ankara clay, Turkey. Faculty of

Engineering, Department of Geological

Engineering, Middle East

Technical University, Ankara, 06531, Turkey

6. K. Bellir, M. Bencheikh-Lehocine, A.-H. Meniai, N. Gherbi (2005). Study of the retention of

heavy metals by natural material used as liners

in landfills. Laboratoire de l’Inge´nierie des

Proce´de´s d’Environnement, De´partement de

Chimie Industrielle, Universite´ Mentouri,

Constantine 25000, Algeria

7. Ilknur Bozbey (2005). Laboratory and field

testing for utilization of an excavated soil as

landfill liner material. Department of Civil

Engineering, Istanbul University, Avcilar, 34320 Istanbul, Turkey