Landfill Gas Generatian A t A

Semi-Arid Landfill

A T H E S I S

SUBMITTED TO THE FACULTY OF GRADUATE STUDLES AND RESEARCH

I N PARTIAL FULFILLMENT O F THE REQUIREMNTS

FOR THE DEGREE OF

MASTER OF A P P L I E D SCIENCE

IN ENVIRONMENTAL SYSTEMS E N G I N E E R I N G

FACULTY OF E N G I N E E R I N G

UNIVERSITY OF REGINA

Douglas A. Opseth

Reg ina , S a s k a t c h e w a n

December, 1998

O Copyr igh t 1 9 9 8 : Douglas A. Opseth

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This research was undertaken in order to characterize gas

emissions fxom semi-arid landfills in Saskatchewan. The

Saskatoon Landfill and the Regina Fleet Street Landfill were

examined for greenhouse gas emissions and spatial emission

variability.

Waste sampling was also conducted at the Regina Fleet Street

Landfill in order to help explain the emission results. The

key findings were an average moisture content of 22%, and an

average interna1 temperature of 1 7 . 3 " ~ . Both of these levels

are significantly below what is deemed optimal for landfill

gas generation.

In addition to waste sampling, shallow gas wells were

installed at both sites to allow for trace gas analysis. The

results of the trace gas anaiysis indicated high spatial

variability at both sites. A range of volatile organic

carbons (VOCs) were detected in the samples. When compared

to landfills in Ontario, the two Saskatchewan landfills

showed low to medium levels of VOCs, with the exception of

freons. Gas samples from both Saskatchewan landfills had

benzene and vinyl chloride concentrations exceeding the

limit set by the Occupational Health and Safety A c t .

iii

Two methods were used, a flux chamber system and a flame

ionization detectox, to examine methane and carbon dioxide

ernissions. The flame ionization detector proved useful for

preliminary analysis of the site, while the flux chamber was

very useful for detailed analysis of emission rates. The

emission rates were estimated as 8842 tonne/year of methane

and 34,353 tonne/year of carbon dioxide at the Regina Fleet

Street Landfill, and 3176 tonne/year of methane and 15,146

tonne/year of carbon dioxide at the Saskatoon Landfill. A

U.S. EPA landfill gas model was used to estimate gas

generation at the Regina Fleet Street Landfill. The field

results were on the higher end of the range suggested by the

model. At both landfills, the ernissions showed high spatial

variability and were concentrated along the d o p e s .

The ernissions rates, 4.65 m3/tonne/year for the Regina Fleet

Street Landfill and 6.6 rn'/t~nne/~ear for the Saskatoon

Landfill, are in the low to medium range of landfill gas

emission rates reported for landfills in North America.

Acknowledgements

1 would like to take this opportunity to express my sincere

thanks and appreciation to rny thesis advisor, Dr. Kim

B a r l i s h e n . Without her time and guidance this project could

n e v e r have been completed. 1 would also l i k e to thank Dr.

Fuller for agreeing to be rny thesis CO-supervisor. 1 would

l i k e t o thank Mr. Gary Nieminen, Mr. Derrick Bellows and Mr.

Tom Bokinac al1 from the City of Regina, who provided

valuable assistance and information required f o r the

completion of this project.

1 would like to t h a n k Roopa Nair for her understanding and

constant encouragement in the completion of this research. 1

would also like to thank my mother, Mary Opseth, and sister,

Megan Opseth, for their support and encouragement throughout

this project. 1 would like to o f f e r special thanks to my

father, Art Opseth, for bis enormous help in the preparation

and editing of this document.

T a b l e of Contents

Abstract .................................................. ii .......................................... Acknowledgements iv

.......................................... L i s t of Tables v i i i

.......................................... List of Figures ..x

.......................................... 1.0 Introduction 1

2 . 0 Background Information on Landfill Gas Generataon ..... 8 2.1 Mechanisms of Landfill Gas Generation ......... ,..8 2.2 Factors Affecting Landfill Gas Generation. ...... 12 2.3 Factors Affecting Landfill Gas Emission ......... 16

3.0 Design Considerations for a Landfill Gas Study ....... 20

3.1 Landfill Gas Field Investigations ............... 20 3.1.1 Monitoring Locations ................. -21 3.1.2 Monitoring Frequency ................. 2 4

3.1.3 Landfill Parameters to Monitor ........ 26 3.1.4 Methods. .............................. 27

3.2 Modeling of Landfill Gas Generation ........... .,34 4.0 Metbodology .......................................... 40

4.1 Regina Fleet Street Landfill G r i d System ........ 4 1

4.2 Preliminary Landfill Gas Investigation .......... 42 4.3 Detailed Landfill Gas Investigation. .........O. *44

4.4 Shallow Gas Wells ............................... SI 4.5 Waste Sample Extraction ......................... 54 4.6 Modeling ........................................ 56

............................... 4.7 Supplemental Data 59

.................................... 5 . 0 F i e l d S t u d y Sites 6 1

................ 5.1 The Regina F l e e t Street Landfill 6 1

.......................... 5.2 The Saskatoon Landfill 67

6 . 0 Results of the Landfil1 Investigations .............. - 7 0

..... 6.1 Regina Fleet Street Landfill Waste Sampling 70

6.2 Regina Fleet Street Landf il1 Preliminary

Landfill Gas Study .............................. 7 3

6.3 Saskatoon Landfill and Regina Fleet Street

.................. Landfill Shallow Gas Well Data 75

6 . 4 Regina Fleet Street L a n d f i l l Gas

................................ Modeling Results 79

6.5 Saskatoon Landfill and Regina Fleet Street

L a n d f i l l Detailed Gas Study .................... -83 7.0 Discussion of L a n d f i l l Investigation R e s u l t s ......... 9 1

.................... 7.1 I n t e r n a 1 L a n d f i l l Conditions 9 1

7.2 Combustible Vapour Concentrations ............... 94 .............................. 7.3 VOC Concentrations 97

7.4 Estimated Landfill Gas Generation Rate ........ 100 7.5 Spatial Variability ............................ 102

7.5.1 The Saskatoon Landfill ............... 102

7.5.2 The Regina E l e e t Street Landfill ... ..l04 7.6 Emission Rate .................................. 108 7.7 Landfill Gas Control Considerations ............ I l 0

8.0 Summary, Conclusions and Recommendations... ......... 113

vii

8 . 1 Summary a n d Conclusions ....S................... 113

8 . 2 R e c o m e n d a t i o n s ................................ 1 2 0

References. .............................................. 122 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bibliography -130

Appendices

Appendix A - Reg ina F l e e t Street L a n d f i l l FID Results.

Appendix B -Regina F l e e t Street L a n d f i l l VOC Results.

Appendix C - Envi ronment Canada k & Lo Values for the LAEEM-

Appendix D - Saskatoon L a n d f i l l Gas E m i s s i o n s .

Appendix E -Regina F l e e t S t r e e t L a n d f i l l Detailed G a s

Results.

v i i i

L i s t of Tables

Table 2.1 - Percentages of various landfill gas

components ..-.........e.-.e............-....ll

Table 5.1 - Types and quantities of waste accepted

.......... at the Regina Fleet Street Landfill 66

Table 6.1 - Data from the basic laboratory analysis

f o r Borehole#l. .........-..m................. 71

Table 6.2 - Detailed laboratory analysis for select samples from Borehole#l ...,...... ..-..72

.................. Table 6.3 - Temperatures from Borehole#2 72

Table 6.4 - Data from basic laboratory analysis for the Test Pit .,...,........................-. .73

Table 6.5 - VOC concentrations (pg/m3) from shallow gas

w e l l s at the Regina Fleet S t r e e t Landfill .... 76 T a b l e 6.6 - VOC concentrations (pq/m3) from four landfill

wells at the Saskatoon Landfill ........... -77

Table 6.7 - Summary of VOC concentration data from the Regina F l e e t Street Landfill ...........-.... -78

Table 6.8 - Summary of VOC concentration data from the

Saskatoon L a n d f i l l ..-...........-.O.........- 78

Table 6.9 - Amounts of waste landfilled from 1981 to

1997 ............1...-..--...0.........--.-...80

Table 6.10 - Parameters and assumptions used in landfill gas simulations .............-..........-..... 82

............. Table 6.11 - Results of landfill gas modeling 83

... Table 6.12 - Data from the Saskatoon Landfill Gas Study 84

Table 6.13 - Emission rates from the Saskatoon L a n d f i l l

.................................... Gas Study 3 4

Table 6.14 - Data from the Regina F l e e t Stree t

Landfill Gas Study ........................... 87 Table 6.15 - Emission rates from t h e Regina Fleet

Street Landfill Gas Study .................... 90

L i s t of Figures

F i g u r e 2 . 1 - Major steps i n the convers ion of o r g a n i c

...................... matter t o l a n d f i l l gas -9

F i g u r e 2 . 2 - L a n d f i l l gas generation c u r v e s ..........,....Hl

.... F i g u r e 2 . 3 - F a c t o r s a f f e c t i n g landfill g a s g e n e r a t i o n 12

................ F i g u r e 3.1 - A s h a l l o w g a s c o l l e c t i o n well 31

....................... F i g u r e 4 . 1 - Flux chamber a p p a r a t u s 50

F i g u r e 4.2 - Waste sampl ing and s h a l l o w gas w e l l

l o c a t i o n s ......................o..,.......... 53

F i g u r e 5 . 1 - Waste ages a t t h e Regina F l e e t Street

.................................... L a n d f i l l 6 4

........... F i g u r e 5 . 2 - The Saskatoon L a n d f i l l s t u d y area. 68

............. F i g u r e 6 . 1 - P r e l i m i n a r y l a n d f i l l g a s r e s u l t s 74

F i g u r e 6 . 2 - Methane e m i s s i o n s ( ~ / h o u r / m ~ ) at t h e

Saskatoon Landfill . . - . , , o . . - . . . . . . . . . . . . , . . . . 85

Figure 6 . 3 - Carbon d i o x i d e emissions (~/hour / rn ' ) a t

t h e Saskatoon L a n d f i l l , , . . ....o.........-.... 86

F i g u r e 6 . 4 - Methane e m i s s i o n s a t t h e Regina F l e e t

S t r e e t L a n d f i l l . . . . - . . . . . . . . . . . . . . . . . . . . 8 8

F i g u r e 6 . 5 - Carbon d i o x i d e e m i s s i o n s a t t h e Regina

F l e e t Street L a n d f i l l .-..........C....-.LL..*89

F i g u r e 7 . 1 - Variablity in FID r e a d i n g s ..............-.... 96

Figure 7 . 2 - Combustible vapour f rom t h e h i g h e s t

c o n c e n t r a t i o n p o i n t s - .......--.........--... -96

1.0 Introduction

In Canada, approximately 90% of the estimated 18 million

tonnes of municipal solid w a s t e d i s p o s e d of each year is

landfilled (Hickling, 1994). Once this waste has been

landfilled, it will begin to biodegrade and produce landfill

gas. The gas generated by the breakdown of the w a s t e in a

landfill is composed of two main components, methane and

carbon dioxide, as well as numerous trace gases.

There is increasing interest in landfill gas generation

because landfill gas can have both beneficiaf and harmful

e f f e c t s . Some of the harmful effects of landfill gas arise

from the fact that it can migrate away from a landfill site

and accumulate in surrounding buildings. When landfill gas,

particularly hydrogen sulfide gas, is present, in

concentrations as low as 0.005 ppm, its offensive odor can

lead to cornplaints from affected r e s i d e n t s (Environment

Canada, 1995). A more serious concern with regards to

methane gas is that it can be explosive. The lower explosive

limit (LEL) for methane gas i s 5% b y volume of air

(Hickling, 1994). Landfill gas, whether it remains at the

landfill site or migrates to neighboring areas, m u s t be

viewed as a potential hazard and nuisance, and dealt with

accordingly.

Certain trace gases presen t i n l a n d f i l l gas can be extremely

dangerous (Young and Parker , 1983; Brosseau and Heitz,

1994) . The most important of t h e trace gases are a group

termed v o l a t i l e o rgan ic compounds (VOCs). These compounds

can evaporate very e a s i l y and c a n be active i n nurnerous

chernical r e a c t i o n s (Great B r i t a i n , 1992a). Two of the most

important VOCs a r e benzene and v i n y l c h l o r i d e ; both of these

gases are known t o be carc inogenic (Walsh e t a l . , 1988;

Brosseau and H e i t z , 1994 ) .

L a n d f i l l gas i s a l s o a c o n t r i b ~ t o r t o the greenhouse e f f e c t .

I t is b e l i e v e d t h a t g l o b a l warming i s p a r t i a l l y caused by

t h e accumulation of var ious greenhouse gases of which

methane and carbon d iox ide a r e two of t h e most s i g n i f i c a n t

( U S . EPA, 1 9 9 7 a f . Because of t h e p o t e n t i a l environmental

problems posed by t h e greenhouse effect, Canada, a long wi th

a l a r g e nurnber of other c o u n t r i e s , have signed agreements t o

s t a b i l i z e o r reduce greenhouse gas emiss ions relative t o

1990 levels b y t h e year 2000. The overall r e l e a s e of carbon

d i o x i d e from landfills is r e l a t i v e l y i n s i g n i f i c a n t compared

t o t h e amount of anthropogenic carbon d iox ide from o t h e r

sources, such as t h e energy i n d u s t r y (Environment Canada,

1997a). On t h e o t h e r hand, methane f r o m l a n d f i l l s may be a

major c o n t r i b u t o r t o t h e greenhouse e f f e c t - I n Canada,

landfills account for from 23 to almost 40% of al1

anthropogenic methane emissions (Hickling, 1994; Environment

Canada, 1997a). Canadian methane emissions, from al1

sources, have increased by 16% in the period from 1990 to

1995 (Environment Canada, 1997a) . This is very important b e c a u s e methane is approxirnately 25 times as powerful a

greenhouse gas as carbon dioxide due to its chemical

interactions in the atmosphere (Conestoga-Rovers &

Associates Limited, 199533). Atmospheric methane is believed

to be responsible for approximately 20% of the global

warming ef fec t (Great Britain, 1992a) .

Landfill gas in the soi1 interferes with a plant's root

system, by depriving it of oxygen (Emcon Associates, 1980).

This is of particular importance because most landfills,

upon closure, become parks or recreational areas. The

destruction of surface vegetation can also lead to surface

erosion and damage to the integrity of the landfill cover.

This in turn can lead to infiltration of moisture, which can

promote landfill gas and leachate generation.

There are several benefits that arise from the production of

landfill gas. The energy potential of methane gas makes it a

valuable resource, which can be extracted and used as fuel

for power generation, either on site or off site. Another

benefit of landfill gas is that its production leads to a

decrease in the strength of leachate, which can lower the

risk of groundwater contamination due to leachate

infiltration (Senior, 1990). A third benefit of landfill gas

generation is that the decomposition of waste that produces

gas also leads to the settling of a landfill site. The

quicker a landfill settles, the sooner it can be used for

post closure purposes.

Little research has been undertaken to study landfill gas

generation in semi-arid landfills, such as those found in

Saskatchewan, Alberta and Manitoba. A number of studies have

been conducted in the United States to determine landfill

gas emissions at larger landfills, p r i r n a r i l y in California

and New York (Bariaz et al., 1990; Pohland and Harper, 1987;

McBean et al., 1995). The majority of these studies have

examined large landfills in areas witn climates

significantly different to that on the prairies. These

studies have tended to rely on landfill gas models and

landfill gas extraction wells or laboratory simulations in

order to estimate landfill gas generation. In addition, the

purpose of many of these studies has been to determine

control and utilization possibilities, not to determine

actual quantities and composition of landfill gas.

In Canada, a number of investigations have been conducted to

determine landfill gas emissions. These studies have

occurred in provinces with specific landfill gas emissions

legislation, primarily Ontario (Williams and Williams, 1995)

and British Columbia. However since the climate in these

locations di f fers from that on the pra ir ie s , the results

from these studies may not be applicable to semi-arid

landfills. In addition, these studies have not exarnined

interna1 landfill conditions. These studies do, however,

prov ide a starting point for designing a landfill gas study

at a semi-arid landfill.

The .City of Calgary has undertaken a preliminary study to

determine if dangerous levels of landfill gas are present,

primarily in surrounding buildings. This study involved

measuring the concentration of methane at a few points at

and around the landfill. Because only low levels of methane

were found, the study was discontinued. The City of Edmonton

monitors landfill gas collected in landfill gas wells in

orde r to properly control that gas. However, they have n o t

undertaken a study to determine total q u a n t i t i e s of landfill

gas being generated nor have they looked at factors within

the landfill which might affect gas generation.

In the fa11 of 1996, the University of Regina in conjunction

with the City of Regina undextook a program to study the

generation and emission of landfill gases at the Regina

Fleet Street Landfill. The first objective of this research

was to investigate available methodologies for measuxing and

modeling landfil1 gas generation and emissions. An

additional objective was to develop and apply a landfill gas

investigation strategy to a semi-arid landfill. A further

objective was to examine landfill gas quantity and quality

information and the influence, on these, of various site

characteristics. The final objective was to provide the City

of Regina with suitable data for evaluating the potential

risks and benefits posed by landfill gas at the Regina Fleet

Street Landfifl.

Chapter Two of this thesis includes background information

on how iandfill gas is generated and the factors that affect

its generation. Information is given in Chapter Three on the

various methods that are available for determining the

quantity and quality of landfill gas. Following this

background information, Chapter Four provides a detailed

description of the methodology used at the Regina Fleet

Street Landfill and the Saskatoon L a n d f i l l to investigate

the emission of landfill gas. Chapter Five covers background

information on the landfill sites that were studied. The

study results are presented in Chapter Six, and these

results are discussed in Chapter Seven. The conclusions and

recommendations of this study are reported in Chapter E i g h t .

2 . 0 Background Information on Landfill Gas Generation

2.1 Mechanisms of Landfil1 Gas Generation

The anaerobic breakdown of organic waste, as depicted in

Figure 2.1, is a multistage process that is carried out by a

variety of organisms. Thexe are three primary microorganisms

involved in the decomposition process. The first two types

of microorganisms break d o m primarily cellulose and

hemicellulose, which constitute from 45 to 60% of municipal

waste and are its two prirnary biodegradable constituents

(Barlaz et al., 1990). Cellulose and hemicellulose are

broken down into three main components: hydrogen (HZ),

carbon dioxide (C02) and acetate (Gardner and Probert,

1992). Certain microorganisms, prirnarily methanogenic

microbes, which are responsible for the generation of

methane gas, use these three products in the generation of

landfill gas.

The quantities and types of landfill gas that are generated

will Vary over the l i f e of a landfill depending on the

stages of decomposition. A landfill site does not have the

conditions necessary for the production of noticeable

amounts of gas until it has aged. Most landfills do not

begin to show significant quantities of landfill gas until

t h e waste has been enclosed for at l e a s t 2 t o 3 years

(Gardner and Probert, 1992). Gas gene ra t ion can con t inue f o r

up t o 100 years , w i t h t h e bulk of the gas being gene ra t ed

within 20 t o 30 years after placement.

1 MONOMERIC COMPOUNDS 1

1 ALCOHOLS, CARBOXYLlC ACIDS. VFAs & l-b 1 I I

ACE TOGENESIS

Figure 2 . 1 - Major s t e p s i n t h e convers ion of organic matter to landfill gas (Gardner a n d P r o b e r t , 1992) .

The composition of l a n d f i l l gas w i l l a l s o Vary over t h e l i f e

of a l a n d f i l l . I n t h e early stages of decornposition, a

l a n d f i l l will t end t o gene ra t e primarily carbon d i o x i d e and

very l i t t l e methane, in terms of volume. However a s a

l a n d f i l l ages, t h e r e l a t i v e amount of carbon d i o x i d e

produced will s t a r t ta dec rease and t h e amount of methane

w i U i nc sease . This change i n gas composit ion w i l l con t inue

until the l e v e l of methane produced is s l i g h t l y h i g h e r t h a n

t h e amount of carbon dioxide produced. The generation curves

of v a r i o u s components of landfill gas can be seen in F i g u r e

2.2.

F i g u r e 2 . 2 - Landfill gas generation curves (Tchobanoglous e t a l . , 1 9 9 3 ) .

In addition to the p r i m a r y gases generated within a

landfill, methane and carbon d i o x i d e , other trace gases are

produced. Trace gases, s u c h as benzene and vinyl c h l o r i d e ,

will b e given o f f in srna11 quantities b u t can pose health

and environmental risks (Brosseau and Heitz, 1 9 9 4 ) . These

gases are not created by t h e breakdown of s i m p l e organic

matter b u t by the decornposition of industrial products or by

the volatilization of c e r t a i n waste compounds, such as

polyvinyl c h l o r i d e ( P V C ) , and a r e t h e n carried t o t h e

l a n d f i l l s u r f a c e by o ther escaping l a n d f i l l gases. The

pr imary sources of these trace gases are s o l v e n t s and

p e t r o l e u m products ( G r e a t B r i t a i n , 1992b) . The relative quantities of each type of gas produced by a l a n d f i l l can be

seen in Table 2.1.

Table 2 . 1 - P e r c e n t a g e s of v a r i o u s l a n d f i l l gas cornponents ( U n i v e r s i t y of California Davis, 1989).

Landfill Gas Component .

Petcent by volume-

Methane 45-60

Carbon dioxide 40-60

Oxygen

Ammonia Sulf ides,

D i s u l f i d e s , Mercaptans, etc

0.1-1.0

0.1-1.0

0-1.0

Hydrogen

[ Trace Constituents ( 0.01-0.6

0-0 - 2

Carbon Monoxide 0-0.2

2 . 2 Factors Aff ecting Landfill Gas Generation

Numerous factors have an impact on the landfill gas

generating potential of a landfill site. Some of these

f a c t o r s are i l l u s t r a t e d i n Figure 2.3, which shows the

breakdown of cellulose. The most important of those factors

are discussed f u r t h e r .

Waste Composition & Types Moisture

Temperature Nutrients & & PH Microbes

Figure 2.3 - Factors affecting landfill gas generation (McBean and Fortin, 1980).

The moisture content within a landfill site has been shown

to be one of t h e most, if n o t t h e m o s t , important factor

affecting the generation of gas ( B a r l a z et al., 1990;

Munasinghe and Atwater, 1 9 8 5 ) . A minimum amount of moisture

is required for the survival and proliferation of the

microorganisms that produce landfill gas. High moisture

content is also required for leaching of various nutrients

f rom the waste to occur (McBean et al., 1995) . Once the nutrients are removed from the waste products, t h e y can b e

more effectively acted upon by the various microbes present

in a landfill site. Landfill leachate also helps to spread

the nutrients and microbes throughout a landfill, thereby

enabling the e n t i - r e site to generate gas. In some cases, a

h i g h moisture content can hinder methane production by

increasing the hydrolysis rate to a level that will create

very acidic conditions not conducive to landfill gas

generation (Barlaz et al., 1990) . Studies have shown that landfill gas generation increases significantly as moisture

content reaches the field capacity of the waste, 45 to 60%

(Environment Canada, 1991), and increases only marginally a s

moisture content approaches 80% (Gardner and Probert, 1992;

Munasinghe and Atwater, 1985). This is far greater than the

typical 20 to 30% (v/v) moisture content found in most

landfills a t the time of waste placement (Gardner and

Probert, 1992) .

The nutrient content of the waste in a landfill is an

important factor in the generation o f landfill gases. The

nutrients from the waste are used for microbial growth,

which in turn, leads to landfill gas generation (Barlaz et

al., 1990) . For maximum gas generation, hydrogen, carbon,

nitrogen and phosphorous must be present (Gardner and

Probert, 1992; Barlaz et al., 1990). Not only must these

elements be present, but t h e y must also be present in

sufficient quantities to allow for microbial growth. The

c a r b o n nitrogen balance is of pr imary importance for

microbial growth. Studies have shown that the optimal carbon

nitrogen ratio is approximately 30:l on a weight basis

(Gardner and Probert, 1992). The presence of toxins, such as

heavy metals, are harmful to microbes and can slow down or

stop rnicrobial growth and subsequent landfill gas generation

(Emcon Associates, 1980). In addition, the intrusion of air

into a landfill is toxic to the anaerobic microorganisms

responsible for the bulk of landfill gas generation. Air can

be pulled into a landfifl if blowers used to collect

landfill gas produce too much suction and draw atmospheric

air through the cover into a landfill.

Temperature is another important factor for a l 1 biological

growth, including rnicrobial growth within a landfill.

Microbes can survive within a relatively large range of

temperatures, 15 to 55OC, but they only thrive in a much

smaller range of temperatures, 32 to 35OC and 45 to 50°C

(El-Fade1 et al., 1996). The m a j o r i t y of the heat in a

landfill is generated within the first 45 days of placement

due to the aerobic breakdown of the waste (Environment

Canada, 1991). The i n t e r n a 1 temperature will t h e n decrease

d u r i n g the subsequent anaerobic stages.

Most deep landfills are very efficient in heat retention and

this usually insures that the temperature within a landfill

remains relatively constant for most oi the year (McBean et

al., 1995). The average temperature within various landfills

is extremely site specific and can reach as high as 40°C, or

higher, in certain landfills (Emcon Associates, 1980).

During long stretches of either cold or hot weather, the

temperature within a landfill site can Vary, particularly in

the upper reaches of a landfill (McBean et al., 1995).

Temperature is one of the reasons why landfill gas

generation is higher in the summer t h a n in the winter

months. The e f fec t of temperature on landfill gas generation

is a concern in climates where there is a greater range of

temperatures throughout the year, s u c h as in Saskatchewan.

Another important landfill characteristic is pH. Landfill

gas production is possible when the moisture within a

landfil1 has a pH l e v e l between 6 and 8, with peak methane

gas production occurring when the pH is from 6.8 to 7.4

(Barlaz et al., 1990). Acid is created during the normal

decornposition of waste. This acid is used by methanogenic

microbes to produce methane gas and caxbon dioxide (El-Fade1

et al ., 1996) . If, however, there are too few microbes to use a l 1 of the produced acid, the pH will decrease and a

landfill can become toc acidic for the microbes, thereby

decreasing methane production. The base of a landfill is an

area where acidic leachate can accumulate which can make

this area unsuitable for the generation of landfill gas.

A final factor t h a t will impact landfill gas generation is

the composition of the landfilled waste. C e r t a i n w a s t e

components, s u c h a s food products, can break down more

easily to produce landfill gas. Other products, such as

scrap wood, will breakdown slowly or n o t at a l l . Landfill

waste that contains a high degree of easily biodegradable

material w i l l produce large quantities of landfil1 gas soon

after placement and will b r e a k down quickly. Waste t h a t is

not broken down very easily will produce smaller quantities

of landfill gas oves a longer period of time.

2.3 F a c t o ~ s Affecting Landfill Cas Emission

Many factors can influence t h e pattern of gas emission a t

and away from a landfill site. Two of the more important

factors influencing the frequency and location of gas

emissions are atmospheric pressure and landfill

permeability.

Landfill permeability has s evera l impacts on the emission of

landfill gas. An impermeable layer in a landfill will create

a barrier to the flow of gas and can force it away from a

landfill site. Cas, like water, follows the path of least

resistance. This means that permeability can dictate the

points of release for landfill gas and the amount of gas

that is released at each e x i t point. Frozen soil and soil

saturation have similar impacts on the location of landfill

gas emissions. When landfill gas meets a barrier, the gas

will flow under it until the gas is sufficiently d i s p e r s e d

or can escape to the surface (Conestoga-Rovers & Associates

Limited, 1995a). If t h e gas can not be released on a

continuous basis, it may build up and be released in large

quantities when conditions allow (Boltze and de Freitas,

1997) .

These factors also help to explain why landfill gas, which

is being generated throughout a landfill, is not released

uniformly. Landfill gas may be channeled, from large volumes

of waste , to specific locations and released in large

quantities.

Atmospheric pressure has shown a negative correlation to the

ernission of landfill gas (Connelly, 1983). A t times of

decreasing barometric pressure the gas concentration

increases at points at and away £rom a landfill site,

Studies have shown t h a t it is t h e rate of change i n

pressure, n o t the final pressure, which has the greatest

impact on the rate of landfill gas emission (Young, 1992;

Young, 1990). It is believed that the pressure drop allows a

large amount of air to be released from the site. This

release of air will decrease oves time even i f the rate of

pressure drop remains constant. The release of air from the

upper r e a c h e s of t h e l a n d f i l l allows l a n d f i l l gas from

deeper areas in a landfill to rnove up and out of a landfill.

As the pressure stabilizes, the gas released from a landfill

decreases and air is able to diffuse back into the landfill

cover, and emissions return to steady s t a t e .

While most research supports the theory that atmospheric

pressure has an impact on the rate of landfill gas

emissions, some field studies g i v e different results. A

study conducted by Environment Canada on £ ive landfills in

very close proximity d i d not show a correlation between Lon

pressure and peak landfill gas ernissions (Williams and

Williams, 1995). A t the f i v e landfills studied, peak

emissions occurred on different dates. I t can be assumed

that they al1 experienced the sarne, or very close to the

same, pressure and should have therefore shown similar

impacts from the changes in that pressure. The reason for

the occurrence of peak landfill gas emissions at d i f f e r e n t

times is not known.

Atmospheric pressure has also been shown to affect the ratio

of methane to c a r b o n dioxide emitted. Methane will be

released in g r e a t e r quantities t h a n carbon dioxide

imediately preceding a dxop i n atmospheric pressure. Carbon

dioxide's higher partial pressure allows it ta dissolve more

easily than methane in moisture found near the surface of

the landfill. This process gives the appearance of a greater

percentage of methane being generated t h a n is actually

occurring. If low atmospheric pressure remains steady for an

extended period, the carbon dioxide being ernitted will

become great enough to overcome absorption and the true

ratio of methane to carbon dioxide being emitted will be

reached (Young, 1992) .

Another factor affecting t h e emission of landfill gases is

the fact that because carbon dioxide has a greater density

than methane, i t can settle at the base of a Landfill. This

can slow the release of carbon dioxide relative to the

release of methane. Also a f f e c t i n g the release of landfill

gases i s the aerobic oxidation of rnethane in the landfill

cover. From 10 to 30% of methane generated in a landfill may

be o x i d i z e d to carbon d i o x i d e i n t h e l a n d f i l l cover

(Environment Canada, 1 9 9 1 ) . This could give the impression

that more carbon d i o x i d e and less methane are being released

than in actually the case.

3.0 Design Considerations for a Landfill Gas

S tudy

3.1 Landfill Gas F i e l d Investigations

There axe many considerations involved in conducting a

landfill gas field investigation. Some understanding of

landfill gas emission and migration patterns are required

before a field study can be conducted.

Studies have shown that gas is not emitted from a landfill

site on a continuous basis (Connelly, 1983; Williams and

Williams, 1995). Instead, it has been shown that gas may be

ernitted from a landfill site in pulses (McBean and Fortin,

1980). By pulses, it is meant that the amount of rnethane gas

reaching a location in a landfill w i l l rise and fa11 over

time; it will not rernain constant. Therefore, i t is very

difficult to determine t h e maximum amount of landfil1 gas

that is actually being emitted from a landfill site. Study

results may be somewhat misleading if it is assumed that gas

emissions are constant over time. Landfill gas emissions

will Vary throughout a range of values. A short-term field

study is only a s n a p s h o t in tirne of landfill gas emissions.

This s n a p s h o t in t i m e may not b e indicative of t h e maximum

o r minimum landfill gas emission rate, but may be somewhere

in the range of actuai gas emissions. However, this does not

invalidate t h e use of short-term studies. A s h o r t - t e m study

will give an indication of t h e emissions a t that time, and

whether the ernissions are high or low relative to other

landfills. A short-term study is generally sufficient to

decide whether control measures are required.

A second error that can occur when conducting landfill gas

studies is due to the mistaken belief that similar results

can be obtained when sampling at the same location at

successive intervals. This mistake arises from the belief

that gas is released in a continuous manner. In order to

obtain sirnilar results on different occasions, monitoring

must be conducted at the same tirne relative to the gas

emission pulses. However, if the gas is being released at a

certain point due to physical factors at a landfill, surface

conditions etc., then monitoring at the same location will

be important- Monitoring at a location where emissions are

high due to physical characteristics c m give valuable

information on changes in emission rates over tirne. Areas of

low emissions can also be monitored to determine if, at any

time in the future, they begin to provide significant

quantities of landfill gas indicating the need for landfill

gas control measures.

3.1.1 Monitoring Locations

An important component in any landfill gas field

investigation is determining the exact locations to conduct

gas monitoring* Ideally, an infinite number of locations

should be monitored, but in reality time and monetary

constraints mean t h a t only a small numbex of locations can

actually be monitored. If monitoring is to be carried out

over long periods, it is important to monitor the sarne

locations to enahle the results t a k e n on different dates to

be compared.

Field studies (Connelly, 1983; Williams and Williams, 1995)

have shown that gas emissions can be highly variable between

locations on a Landfill site, even between sampling

locations in close proximity CO each other. Landfill gas

studies (Bagchi, 1996) h a v e also shown a high degree of

variability between recorded values taken at the same

location but at different elevations within a single

landfill gas extraction well. Because of the high degree of

vzriability between recorded values at various depths and

locations, it is essential for any long-term study that care

be taken to i n s u r e that the same locations and elevations

are monitored over time.

The primary reasons for conducting most gas studies are to

determine how much gas is being emitted from a landfill

site, and how much gas is migrating away from the site and

into surrounding areas. Therefore, it is important to

conduct any monitoring across the e n t i r e surface of a

landfill to its perimeter and possibly beyond. This does not

mean that al1 areas have to be sampled. Emissions can be

estimated based on data from other similar areas t h a t have

shown comparable emissions rates i n the past. By monitoring

landfill gas at a landfill site's perimeter, any g a s that is

migrating away from a landfill site will be detected. In

addition to monitoring at the perimeter, monitoring on the

surface of a landfill will give d a t a that can be used in

determining a total ernission rate for a landfill (Williams

and Williams, 1995). Any permanent monitoring locations

should be placed in l o c a t i o n s that will n o t be disturbed by

activities such as landfill traffic, waste t i p p i n g o r the

f i n a l closure o f a landfiIl s i t e .

It is also important to concentrate gas sampling at t h e

locations t h a t have the highest emissions. Because landfill

gas emissions Vary spatially over a landfill, i t may be

necessary to determine t h e areas of high emissions by means

of past studies, preliminary s tud ies or interviews with

landfill operators. The areas of high emissions are of far

greater interest than a r e a s of low emissions because a

majority of landfill gas rnay be emitted £rom a relatively

small nurriber of points on a landfill surface.

3.1.2 Monitoring Frequency

The fact that landfill gas can be emitted and migrate from a

landfill site in pulses (Connelly, 1983; El-Fade1 et al.,

1995) should be taken into account when determining a

monitoring frequency for long-term monitoring programs. If

this is not taken into account, monitoring may take place

between pulses, which could give a false impression of the

amount of gas being emitted from a landfill site. Several

important steps must be t a k e n in order to determine the

optimal monitoring frequency for landfill gas.

Some gas emission and migration studies have shown that

landfill gas fluctuations will follow a pattern as long as

the conditions within and around a landfill remain constant

(McBean and Fortin, 1980; Connelly, 1983) . If the frequency of peak emission can be determined by means of intensive

sampling, t h e n sampling can take place at those times as

long as conditions remain constant.

The frequency of gas emission will Vary with regards to

temperature changes, changes in conditions within a landfilf

site and atmospheric pressure changes (McBean and Fortin,

1980; Connelly, 1983). Because of this variability, it is

important that any gas monitoring program has a certain

degree of flexibility in order to handle the effects of

changing conditions on landfill gas emissions. A l s o ,

sampling under varying conditions will give insight into the

impact of different conditions on landfill gas emission.

Peak gas emission at one location may not coincide with peak

landfill gas emission at another (Erncon Associates, 1980).

The important considerations for short-term studies are

different than for longer-term studies. In longer-term

studies, sampling is designed around the time of peak

landfill gas emissions, however, i n short term studies this

can not be done. While long-term landfill gas studies

examine temporal changes in gas emissions, short-term

studies provide a rapid assessment of l a n d f i l l gas emissions

a t a s i n g l e p o i n t i n time. The most important factor for

short-term studies is to obtain as many samples as possible

over the entire landfill surface in as fast a tirne as

possible to get an indication of emissions at one point in

tirne and under uniform conditions.

One additional consideration is the location of the landfill

in question, and the risks posed to the environment and the

surrounding population by landfill gas. Urban landfills that

are in close proximity to residences may require more

frequent monitoring to insure that there îs no risk or

nuisance to the public. This level of frequent sampling may

not be required for landfills located in more remote areas.

3.1.3 Landfill Parameters to Monitor

The two most important landfill gases to monitor are methane

and cafbon dioxide. These are not the o n l y landfil1 gases

generated, but t h e y are the most p r e v a l e n t gases and

significant in terms of both environmental impact and

potential utilization (Emcon Associates, 1980). Trace gases

should also be rnonitored because, while they may be present

in relatively small quantities, they can pose significant

health risks. The primary trace gases of interest are VOCs,

such as benzene and vinyl chloride.

Atmospheric and ground temperatures shouid be rnonitored in

addition to landfill gases. Landfill gas generation and

emission can be temperature dependent (Erncon Associates,

1980). It is important to know the temperature at the time

of monitoring in order to interpret data properly. Certain

monitoring procedures require temperature data for the

calculations that are used to determine landfill gas

emissions.

Landfill gas modeling is quite often conducted in

conjunction with a landfill gas investigation. In order to

accurately carry out landfill gas modeling, it is important

to collect landfill data that c a n be used to calibrate the se

models. Some of the data that would be most u s e f u l are

moisture content, pH, temperature, composition, and t h e

location and age of v a r i o u s landfill wastes , Waste and soi1

sampling can prov ide an indication of t h e s e parameters

either by use of a borehole or a trench, or estimates from

previous studies. The d a t a need to b e collected only once if

landfill conditions remain constant, but updated if landfill

conditions change. Because conditions can Vary within a

given landfill, it may be necessary to co l l ec t waste samples

in a number of locations a t the same landfill. Field data

also prove useful in estimating the landfill gas generation

potential for a given site.

3.1.4 Methods

There are essentially three standard methods for monitoring

gas at a landfill site: passive non-intrusive sampling,

passive intrusive sampling and active intrusive sampling.

The term active refers to actively pulling gas samples from

a landfill, for example by means of a blower. Intrusive

sampling refers to collecting samples by penetrating the

surface of a landfill, for example with a well, while non-

intrusive sampling collects samples at the landfill surface.

Passive non-intrusive sampling collects landfill gas sarnples

in the air above the landfill surface or directly on the

landfill surface. The main advantages of passive non-

intrusive sampling are that it is easy and inexpensive to

conduct, and sampling can be conducted at a variety of

locations at and around a landfill site in a relatively

short period of time. Also, because this type of sampling is

very mobile, it can be used in s u c h a way as to not

i n t e r f e r e w i t h landfill operations. The major disadvantage

of passive non-intrusive sampling is that it can give less

accura te results than more active intrusive sampling (Great

Britain, 1992a). The gas that escapes from a landfill site

is sampled not the gas generated within the landfill itself.

However, this may be e x a c t l y what is desired if the purpose

of a study is to determine the amount of escaping landfill

gas in order to determine c o n t x o l measures. Other methods

may be needed to determine the amount of gas being generated

in o r d e r to determine the potential for landfill gas

utilization.

There are a nurnber of methods that are available for passive

non-intrusive sampling. One of these methods is an ambient

air sampler . Ambient air samplers collect and analyze gas

samples at a landfill's surface. These samplers can measure

individual gases, such as methane, or combustible vapours.

The benefits of this type of sampler are that it is

relatively cheap and easy to use. Ambient air samplers can

be used effectively in preliminary work for determining the

areas of the landfill t h a t have the highest gas emissions.

The primary disadvantages are that ambient air samplers do

not allow an emission rate to be determined and c a n not

speciate b e t w e e n various gases in a single sample.

Another type of passive non-intrusive sampler is a flux

chamber. A small portion of a landfill cover is enc losed

within a hemisphere, into which a known quantity of c l e a n

sweep gas is introduced. The sweep gas allows for t h e

determination of an emission rate and acts to dilute the

landfill gases that in h i g h concentrations can be damaging

to analysis equipment. The clean sweep gas then mixes with

the emitted landfill gas, and after a short time, the mixed

gas is withdrawn for analysis. By assuming that the flux

chamber acts as a completely mixed reactor and that the

inflow of landfill gas is much srnaller than the inflow of

t h e s w e e p gas, an emission rate for various types of

landfill gases can be determined. By collecting a large

number of samples over the s u r f a c e of a landfill, an

emission rate for a landfill can be determined. The

advantages of this type of sampler are that it is cheap and

relatively easy to use, and allows f o r ga s speciation and

the determination of an emission rate.

There are a number of disadvantages to using a flux charnber

for landfill gas sampling. Because only a small area is

covered by the flux chamber, a large number of samples are

needed in order to determine a n accurate emission rate for

an entire landfill. Because very small quantities of

landfill gas are analyzed, there is the possibility of cross

contamination. Cross contamination can be addressed by

carefully covering the flux chamber during sampling and

carefully cleaning collection equipment after each use.

Another problem found in some flux chamber designs is that

as the f l o v of sweep gas is increased to compensate for high

landfill gas emission rates, internal pressure can build up

which may impede the inflow of landfill gas into the flux

chamber. This problem is addressed by increasing the area of

the gas outlet to reduce internal pressure (Williams and

Williams, 1995), or by keeping the sweep gas flow rate low

(University of California, Davis , 1989) . Even taking into

account these problems, studies have shown that if used

properly, flux charnbers can effectively and accurately

determine landfill gas emissions (Williams and Williams,

1995; Eklund, 1992; Reinhart et al., 1992) .

A second method for landfill gas sarnpling is by passive

intrusive sampling using shallow depth gas probes. These

probes are generally based on the Method 25-C design,

provided by the United States Environmental Protection

Agency ( U . S . EPA) for use in collecting landfill gas

samples. These probes are comprised of a 1 to 2 m hollow

pipe that is open and perforated at the bottom and sealed at

the top with a valve that allows for the withdrawal of a gas

sarnple. The shallow well is placed I m into the landfill as

shown in Figure 3.1.

Pump

Figure 3.1 - A shallow gas collection well.

After the conditions within the well have reached steady

state, at l e a s t 24 hours, a gas sample can be withdrawn. The

sample is withdrawn by pumping the sample into a collection

canister. The sample can then be sent for a n a l y s i s . The

advantage of the gas probe is that it provides more use fu l

data t h a n ambient air sarnpling, because it collects samples

£ r o m within the l a n d f i l l i t self as opposed to collecting

samples at the l a n d f i l l surface. Also, t h e s e probes are

relatively cheap t o cons t ruc t and easy t o use, thereby

enabling multiple probes to be set up and used a t a landfill

site. The major disadvantages to the probe are that it only

samples to a relatively shallow depth within a l a n d f i l l , and

it i s not possible to determine emission rates over an

e n t i r e landfill site. Shallow gas wells are i d e a l l y suited

for collecting point gas samples that can be sent to a

laboratory and analyzed in greater detail than can be

accomplished in the field, such as when analyzing for VOCs

or other trace gases.

The final method of gas sampling is by intrusive active gas

sampling, primarily by the use of deep landfill collection

wells. These wells can either be used individually or they

can be connected to a larger gas collection systern. The key

factors i n the installation of a collection system are that

it must reach al1 parts of a landfill and it must have a

suitable and powerful blower. The blower for the wells must

be powerful enough to pull landfill gas out, but it should

not pull air into the landfill because this will hinder

landfill gas generation (Van Zanten and Scheepers, 1990).

The benefit of this type of collection system is that it

can, if i n s t a l l e d properly, collect landfill gas from the

majority of the landfill and can give very detailed data.

The extraction efficiency for a properly designed c o l l e c t i o n

system can be in excess of 85% (Hickling, 1994) . The major

problem in the use of this type of system is t h e price.

Because o f the variable nature of landfills, a large number

of wells would be required- In addition, because some

landfills contain a large amount of rubble, drilling wells

for a collection system may be extremely difficult. This

type of sampling would be useful if a large enough quantity

of landfill gas is believed to be present to warrant

collection for large scale destruction or utilization.

A modified active intrusive sampling procedure can be used

if more detailed information is desired on the quantity and

quality of gas being produced at a landfill site. This

method involves drilling a gas well and surrounding it with

gas probes circling the well at various distances and

depths. The purpose of this type of procedure is to

determine the "zone of influence" for a given gas well. By

pulling gas from the well and monitoring the pressure in the

probes, a rough estimate of the area that is being

influenced by that well can be determined. %y knowing the

volume of w a s t e and the quantity of gas being drawn from

that volume of waste, an estimate of the amount of gas

generated per unit volume of waste can be determined. This

is very useful data required to examine the viability of a

gas utilization system. The problem with this type of

analysis is that it is very expensive and time consuming,

and should only be carried out if it is believed that there

is a large quantity of gas being generated.

3.2 Modeling of Landfil1 G a s Genetation

Since accurate r e s u l t s from field tests are difficult and

expensive to obtain, landfill gas modeling can be used in

place of field investigations or as a supplement to them.

Because the basic equations for the breakdown of landfill

material into landfill gas, such as the one seen in Figure

2 . 3 , are known, the simplest method for estimating landfill

gas generation is by stoichiometric methods. Using

stoichiometric methods, an es t imate can be made for the

telease of methane from a landfill; one estimate is 270 L of

CH4/kg of wet refuse (Emcon Associates, 1980). Even higher

estimates c a n be obtained if the waste is assumed to be

composed of only cellulose material. These estimates are

based on ideal conditions and require specification of a

chernical formula for the waste. Because actual landfill

conditions and waste are not homogenous or static, more

cornplex rnethods must be used to estimate landfill gas

generation over time.

There are a number of more cornplex methods available for

rnodeling landfill gas generation. Al1 of the methods attempt

to predict t h e outcome of the various reactions within a

landfill that produce gas. Generally, landfill gas models

try to account for the influence of key parameters, such as

temperature and moisture content.

The major problern w i t h landfill gas modeling is that there

can be a large amount of uncertainty in the background data

required by various models. In many landfills, particularly

older landfills, there may be a general lack of information

on the locations, ages and types of waste present. There may

also be a lack of information on the key conditions w i t h i n a

landfill, such as moisture content and pH.

Another factor that can negatively a f f e c t the outcome of

landfill gas modeling is t h a t conditions within a landfill

are extremely variable. This may mean that modeling a

landfill as a single homogeneous unit is not suitable and it

may be necessary to rnodel each homogeneous subpart

independently. In order to rnodel subparts, however, very

detailed information will be required, and in many cases

this information may not be available.

Another issue in modeling studies is determining the

accuracy of the final results. In cases where actual field

data are not available, the mode1 will be the sole source of

information on landfill gas g e n e r a t i o n . The accuracy of

landfill gas models will depend to a very large extent on

both the quantity and quality of the input data. Models that

are cafibrated based on data from other similar landfills

have been shown t o corne within t30% of actual gas generation

(Zison, 1990), while with good accurate long-term site

specific data results of f10% can be achieved. Of course,

the mode1 results are being compared to field data which

will also have some error associated with thern.

At present, there are very few, if any, models available

that are capable of relating al1 generation influencing

parameters to landfill gas generation, or of determining the

effects of the var ious parameters on each other. Instead of

relating individual parameters to landfill gas generation,

most models group the cumulative ef fec t of the parameters

into one or two coefficients that c a n be modified for

various landfill conditions.

The best possible site-specific data should be used to

insure the best modeling results for a given landfill are

obtained. For modeling studies, it is also important to

obtain the most accurate information on past, present and

future landfill conditions. The primary site data required

by most models are waste quantities and the amount of waste

in place. Because estimates f o r various coefficients needed

by most models, such as decay coefficients, are not usually

available or are difficult to obtain, estimates of these

coefficients must be made.

There are three primary types of rnodels used for estimating

landfill gas generation:

1. Zero order kinetic models;

2. First o r d e r kinetic models;

3. First o r d e r multiphase kinetic models.

Zero order kinetic rnodels operate under the assumption that

landfill gas generation is constant over time. Essentially

this means that the age of the waste is not taken into

account. T h e s e models are not useful in the majority of

landfill studies but can be used to determine emissions

nationally or globally (Peer et al., 1993). They can also be

used in cases where there is very slow landfill gas

generation and landfill conditions remain constant over

tirne. A zero order kinetic equation can

3.0 (McBean et al., 1995) :

be seen in Equation

(3 0)

Where : time between waste placement and landfill gas generation; volume of CH4 remaining to be produced a f t e r time T; gas production rate constant.

First order kinetic models differ from zero order models in

that time is taken into account. These models are cornrnonly

used because they are simple and have been shown to give

accurate results (Zison, 1990). The primary equation that

first-order kinetic models are based on is Equation 3.1

(Erncon Associates, 1980) :

Through Equation 3.1, it is possible t o determine the

generation of landfill gas over tirne b y assuming that t h e

gas production rate decreases exponentiafly.

First order multi-phase kinetic models are a variation on

the standard first-order model with the only difference

being that the waste in a landfili. is broken into various

subparts. The subparts of a landfill are based on the speed

by which the various types of waste will be broken down.

Usually three subparts are used: slow biodegradability, such

as plastics; medium biodegradability, such as wood; and

rapid biodegradability, such as food scraps. This type of

model can be more accurate t h a n the standard first-order

kinetic model, if proper data are available on the t y p e s and

ages o f waste present in a landfill (Oonk et al., 1994). The

problem with this type of model is that it requises very

detailed information on the quantity of each type of waste

present, the rate of decomposition of each type of waste,

and the quantities of each type of waste brought to a

landfill every year. Very often this information may not be

available.

The variability within a landfill and the possible l a c k of

information on landfill characteristics and inputs make

modeling landfills very difficult. These difficulties mean

that there will be a degree of uncertainty with any modeling

results. If possible, the results should be verified w i t h

actual field data.

4 . 0 Methodology

Because of the complexity of the Regina Fleet Street

Landfill gas investigation, it was carried out in a number

of phases. The initial phase was a survey of the landfill to

create a grid system that could be used to orient the

landfill gas sampling. Following the construction of the

landfill grid system, a preliminary gas investigation was

undertaken to gather information necessary for designing the

detailed landfill gas investigation.

Following the preliminary phases of the landfill gas

investigation, a detailed landfill gas investigation was

carried out. In addition to the detailed landfill gas

investigation, two shallow gas wells were installed in otder

to collect samples for gas speciation. To assist in the

interpretation of the collecteci data, waste samples were

collected at various locations and depths in the landfill

and analyzed for a variety of parameters. To complete the

landfill gas study, computer simulations of the landfill

were preformed to aid in long term gas generation

predictions.

4 . 1 Regina F l e e t S t t e e t Landfil1 G r i d System

Before field data collection, it was necessary to develop a

grid system based on a survey of the Regina Fleet Street

Landfill. This grid system would be used to orient the

sample collection process and to insure that al1 required

sectors were sarnpled. A City of Regina survey crew laid in a

30 m b y 30 rn grid. The grid began in the southeast corner of

the landfill and ended in the northwest corner. The grid ran

east to West and north to south. The 30 m by 30 m grid s i z e

was based on discussions between the University of Regina,

Environment Canada and the City of Regina. The final

decision to u s e a 30 m by 30 m grid was based on a

compromise between getting the finest possible grid that

could be s u r v e y e d in a reasonable time frame of one to two

weeks. An additional consideration was that large numbers of

grid stakes c o u l d be knocked down by the daily operations at

the landfill site. This would încrease the difficulty in

determining exact sampling locations.

The survey crew constructed the grid by placing a painted

stake with florescent tape at the vertex of each g r i d

square. The stakes were lettered and numbered using a

reference system requested by the University of Regina. This

reference system allowed any square to be easily located on

the landfill site.

Because each survey stake had exact reference coordinates,

it was possible to locate the grid and indicate emission

rates on landfill maps. Certain areas that were eithex

located in a curxent active area, an inaccessible area, or

within the landfill maintenance yard were not surveyed.

4 . 2 Preliminary Landfill Gas Investigation

A detailed study was reqüired in order to obtain data that

would aid in the determination of landfill gas emission

rates as well as landfill gas speciation. Because detailed

landfill gas sampling would be very time consuming, every

grid square at the landfill could not be sampled in a

reasonable time frame. A preliminary study was used to

determine tne areas of high gas concentrations so that they

could be studied in greater detail. It was possible to

design a detailed study that, while not sampling every

location, would sample the most important locations in terms

of gas emissions. The preliminary study allowed the detailed

study to be carried out in only a rnatter of weeks instead of

montns.

To conduct a rapid preliminary study, a flame ionization

deteccor (FID) w a s used to collect surface landfill gas

samples. A FID collects a gas sample from the air and burns

it within the analyzer. The FID t h e n gives a reading in

parts per million (pprn) of combustible vapour present in the

analyzed sarnple. Because methane, a key landfill gas

component, is combustible it was decided, for the purposes

of the preliminary study, that high €ID readings would be

taken as an indication of high landfill gas emissions.

Determining these areas would give a strong indication of

the locations where there would be greater landfill gas

emissions, which could later b e studied in detail. The FID

also allowed for the determination of the areas that had

sirnilar emissions so that a few representative samples could

be taken from those areas.

The FID, a HeathTech THC analyzer, was borrowed, for the

duration of the landfill gas study, from the Environmental

Research and Management Division (ERMD) of Environment

Canada, located in Ottawa. This FID is designed and built by

HeathTech Consulting Ltd. for use in determining

concentrations of combustible vapour. This analyzer had been

used to determine landfill gas concentrations at a number of

landfills throughout Canada. The FID runs on an interna1

battery and a small canister of hydrogenhitrogen rnix fuel.

The entire unit is easily portable @y one person and can

operate for several hours b e f o r e being refueled and

recharged. The FID can measure concentrations of combustible

vapour from 10 to 1000 ppm (as methane) and due to

modifications made by Environment Canada it can detect

concentrations up to 2000 ppm. The gas sampLe is drawn into

the analyzer by an i n t e r n a 1 pump, through a small flexible

boot that is placed on the landfill surface. This allows

samples to be taken from the landfill surface with a minimum

of atmospheric contamination.

Samples were taken at every g r i d stake over the entire

landfill site. This included some areas t h a t had not been

surveyed, s u c h as the landfill maintenance yard. The FID

also was equipped with an alarm which sounded any time

combustible vapour levels were above a pre-set level. This

alerted the pesson conducting the field test of high

concentrations of combustible vapour as they were walking

between points. These points were t h e n sampled and the

locations referenced frorn surrounding stakes.

4 . 3 Detailed Landfiil Gas Investigation

A number of options were considered for collecting detailed

landfill gas data which would later be used t o determine

both an emission rate for the landfill, as well as landfill

gas s p e c i a t i o n .

The use of a landfill gas collection system t o pull gas from

a landfill was not a viable opt ion . There is currently no

collection system in place at t h e Regina landfill site and

the possibly l a r g e capital c o s t ta install one, would be

prohibitive. In addition, the amount of landfill gas

expected from this semi-arid landfill may be too low to

justify its collection and subsequent utilization, at least

in this preliminary stage.

A second option that was considered was the use of a series

of deep landfill gas extraction wells. Since the landfill is

extremely variable, a large number of wells would be

required in order to obtain samples representative of al1

parts of the land£ill. A second problem is that since a

large amount of rubble has been buried in the landfill, it

would be difficult to get enough boreholes drilled deep

enough into the landfill. The large number of wélls that

would be required made this option cost and time

prohibitive.

S i n c e below surface methods of collecting landfill gas

samples were al1 extremely costly, it was decided that non-

intrusive methods were the most viable option for landfill

gas collection. The method to be used would have to able to

allow for an emission rate to be determined plus allow for

gas speciation of at least methane and carbon dioxide. The

rnethod would use equipment that is portable enough to allow

for sampling of the e n t i r e landfill to take place, and

durable enough to withstand prolonged use in the field.

The method that was chosen for the collection of the

detailed samples was a flux chamber collection system. Flux

chambers have been used f o r a nurnber of years in t h e United

States for the collection of VOC data as well as other kinds

of emissions (Pohland and Harper, 1987; Eklund, 1992). Flux

chambers resemble a hemisphere that is placed on the

landfill surface in order to collect emission samples. T h e

b a s i c equations used to determine landfill gas emissions

using the flux chamber are as follows:

Where :

Froc = the total volumetric flow o f gas i n t h e

dilution tube sampler (L/min);

Fd = the metered flow of diluent gas entering the flux

chamber (L/min) ;

F, = the desired volumetric flow rate of the target

species entering the sampler over t h e area of

the flux charnber (L/min), compensated to 25'~.

Where :

C, = the measured concentration of the target species

i n the gas sample after thorough mixing w i t h the

diluent gas i n t h e f l u x chamber ( p a r t s p e r m i l l i o n

( v / W 1 -

S u b s t i t u t i n g Equation 4 . 1 i n t o E q u a t i o n 4 . 2 y i e l d s :

Assurning F, >>> Ft, then:

Re-arranging Equa t ion 4 . 4 t o solve for Ft yields:

Equation 4.5 gave an ernission rate f o r a target gas f o r t h e

a rea , 0 .0169 m2, covered by t h e f l u x c h a m b e r . T h i s emission

r a t e was used a s an average f o r the entire s q u a r e i n which

the sample was taken.

Several impor tan t considerations had t o be addressed when

u s i n g a flux c h a m b e r . F i r s t l y , b o t h t he type of sweep gas

and the flow rate of t h e sweep gas had to be considered.

Almost any gas can be used as long a s i t is pure, dry and

does n o t c o n t a i n any of t h e gases being studied. P u r e

nitrogen was chosen as the sweep gas because it is readily

available and relatively cheap. The decision on flow rate

was more difficult because there are problems with using

either a high flow rate or a low flow rate. If a low flow

rate is used, it is possible to get a more detailed reading

on the gas emissions. The problem is that using a low flow

rate can result in a much longer time for conditions within

the flux charnber to r e a c h steady state (Eklund, 1992). Also,

if there are high emissions occurring, a low flow rate c a n

make the assumption that Fd is much greater than Ft invalid.

Based on these factors, the chosen flow rates were 5 L/min,

for average landfill gas emissions, and 10 L/min, for high

g a s emissions.

Another consideration was the placement depth of the flux

chamber. It must be placed at a minimum distance into the

ground in order to insure a proper seal, thereby trapping

landfill gas in the chamber and keeping atmospheric air o u t .

A standard minimum depth of 2.54 cm is used in many flux

chambelr applications in the United States (Eklund, 1992).

Environment Canada indicated that their experiments showed

that a minimum depth of 4.45 cm would offer the best

protection against the strong winds comrnon o n the prairies

(Williams and Williams, 1995). In addition to the increased

depth for the flux chamber, two separate containers were

placed over top of the flux chamber to insure that wind did

not impact the sampling.

The final consideration was the number of samples to take.

As in most studies, it is best to take as many samples as

tirne and money allows- Based on the FID data, it was decided

to conduct extensive sampling on the slopes of the landfill

because these areas showed higher combustible vapour

concentrations than other a r e a s . The top and base areas of

the landfill, were sarnpled only sporadically, due to the low

combustible vapour concentrations found over these areas.

One sample was randomly t a k e n per studied square unless

concentrations exceeded 500 ppn for either carbon dioxide or

methane . If concentrations greater than 500 ppm were found,

t h e n two additional samples were taken randomly within the

same square. The sweep gas f l o w rate was increased to 10

L/min to compensate for concentrations greater than 500 ppm.

Figure 4.1 illustrates the flux chamber setup that was used

at the Regina Fleet Street Landfill. The flux chamber was

inserted into the ground to a depth of approximately 4.45

cm, Once it was inserteu, the sweep gas was turned on to the

desired level, usually 5 L/min. Once the flux chamber had

reached steady state, approximately 5 minutes, a sample was

drawn from t h e flux chamber by means of a small hand pump

which pulled the sample from the chamber into a Teldar

sample bag. When the sarnple was collected, the temperatures

within the flux chamber and i n the ground below the chamber

were recorded u s i n g a small themorneter. Af t e r t h e sample

was t a k e n , the f l u x chamber was relocated and the sample bag

was brought back for a n a l y s i s .

I Pump

Gas Sweep A Nitrogen

Gas

L a n d f i l l Surface

Figure 4.1 - Flux chamber appa ra tu s .

The a n a l y s i s of the samples was carr ied out u s i n g a B d K

Mode1 1302 Multi-Gas Analyzer, manufactured by Brüel & Kajar

Inc. The analyzer was located in a van t h a t could be moved

closer t o the sarnpling area. A srnall gasoline g e n e r a t o r

powered the ana lyze r . The BhK analyzer was used to measure

carbon dioxide and rnethane and was capable of measur ing

c o n c e n t r a t i o n s up t o 15 ,000 ppm of gases. The B b K a n a l y z e r

works by moni tor ing the changes i n wavelength o f i n f r a r e d

l i g h t as i t passes through the gas sample. The sarnple bag

was hooked up t o the analyzer, and an interna1 pump drew a

sample into the a n a l y z e r f o r a n a l y s i s . The gas i n each

sample bag was analyzed three times and the average of the

results was used to determine the final concentration,

To insure proper calibration of the B&K analyzer, i t was

periodically checked for zero and span concentrations. This

was d o n e on a twice-daily basis. To check for the span, pure

concentrations of both methane and carbon d i o x i d e were run

through the analyzer and the results were noted. To check

for the zero, pure nitrogen was run through the analyzer and

the r e s u l t was recorded. These resufts were latex used

modify the data to compensate for variations in the

operation of the analyzer.

The emission data for areas at the landfill that were not

sampled were estimated by averaging the emission results

from surrounding, sampled, a r e a s . The areas used to average

other areas had to have similar combustible vapour

concentrations, were i n the same area, and had similar

topography.

4 . 4 Shallow Gas Wells

Deta i led analyses had to be made not only of the primary

gases, methane and carbon dioxide, but also of very small

quantities of trace gases in order to proper ly analyze

Regina's Landfil1 gas. Because of the large number and small

quantity of these gases, the B & K analyzex could not be used

and the samples had to be analyzed in a laboratory using

more cornplex a n a l y s i s equipment. I n addition, because of the

srna11 quantities of the trace gases present, a different

sampling method had to be used.

Zt was decided to use an approach modified from one used by

the U.S. EPA to collect trace gas samples. The procedure

used by the U.S. EPA is called Method 25-C and involves

placing a shallow gas well in a landfill to collect gas

samples. Two wells were constructed of 5.1 cm s teel p i p e

perforated a t the bottom and placed 1 m into the ground. Two

wells were installed on top of the south dope of the Regina

landfill. The location of these wells can be seen in Figure

4.2.

The wells were sealed and allowed to sit for two days;

t e f l o n tubing was inserted into the wells and a sample was

drawn from e a c h well. The samples were drawn into evacuated

stainless steel SUMMA canisters- The canisters were shipped

to Environment Canada in Ottawa for analysis by means of a

gas chromatograph equipped with a mass selective detector.

' D I ,

., 3: '-.. . m --

4 . 5 Waste Sample Extraction

Waste samples were required to better understand the

conditions within the landfill and to gain some insight that

could later be used to interpret the landfill gas results.

Ideally, these waste samples should corne from a variety of

waste ages and provide information on pH, moisture content,

nutrients, temperature and organic and inorganic components

of the waste. In order to obtain waste of an o lde r age, 20

to 30 years old, a borehole was drilled through the south

d o p e from the top to the bottom of the landfill. To collect

samples of younger age waste, 1 to 5 years old, a trench was

dug on the top of the landfill. The locations of the

boreholes and the trench can be seen in Figure 4.2.

AGRA Earth and Environmental Limited (AEE) was hired to

drill the borehole and excavate the trench and to collect

the samples for analysis. In addition to the collection of

waste sarnples, AEE (1998) installed a thermistor to monitor

landfill temperatures, and a suction lysimeter and bailer to

sample leachate.

To collect the waste samples from the older section, two

boreholes were drilled. Both boreholes were 0.6 m in

diameter and were drilled using a LDH 80 piling r i g to

depths of 21.5 m and 10.7 m, respectively. The reason f o r

the second borehole was to allow for the installation of the

thermistor in one borehole, and the lysimeter and piezometer

in the other. Waste samples were collected at incrernents of

1 m in t h e 21.5 m deep borehole, and at increments of 1.5 m

below a depth of 4.6 m in the 10.7 m deep borehole.

Temperature readings were recorded at depths below 18 rn in

the 21.5 rn deep borehole, and at depths below 4.6 m in the

10.7 rn deep Sorehole .

A t rench was excavated w i t h a track-mounted backhoe to a

depth of 5 m to collect younger age waste samples. Samples

were collected at 1 rn intervals. The trench was backfilled

after the collection of the waste samples.

A l 1 waste samples were collected and placed in heavy-duty

collection bags and were subsequent ly sent to the

Saskatchewan Research Council (SRC) in Saskatoon for

analysis. The samples were analyzed for moisture content,

pH, loss on ignition, organic compounds, nutrients and

metals.

4 . 6 Modeling

The U.S . EPA Landfill Air Emissions Lstimation Mode1 (LAEEM)

is used for estirnating emission r a t e s of methane, carbon

dioxide and other individual toxic po l lu tant s from

landfills. The LAEEM is one of the most widely used landfill

emission models and its predictions form the basis for

r e g u l a t i o n s in B r i t i s h C o l u m b i a and t h e United S t a t e s

(Conestoga-Rovexs & Associates Limited, 1 9 9 5 a ) . The LAEEM i s

based on the Scholl Canyon first order single stage kinetic

model for landfill gas generation. The Scholl Canyon model

assumes that landfill gas generation w i l l b e g i n w i th no l a g

time between the time of waste placement and the beginning

of landfill gas generation. This means that the mode1

assumes t h a t peak l a n d f i l l gas generation occurs imrnediately

after the placement of the waste and then decreases over

time. The basic e q u a t i o n used by t h e LAEEM is derived from

Equation 3.1:

Where:

G , = ernission r a t e from the ith section (Mm3 of

CHJyear) ;

k = methane generat ion r a t e (l/year) ;

L, = methane generation potential (m3 of CH4/tonne

of refuse) ;

Mi = mass of refuse in the irh section ( M t ) ;

rI = age of the ith section (years);

i = sub-sections of the whole landfill.

As can be seen £rom Equation 4.6, the LAEEM requires only

four input variables, which are the amount of waste in

place, t h e age of the waste, k and L,. The user has to input

the tonnes of w a s t e in place or an acceptance rate for every

year that the landfill h a s been in cperation up to the

present year. If the waste in place or the acceptance rate

is not known then the LAEEM can estimate these values based

on landfill volumes. The LAEEM will also ask for the year

the landfill opened and the maximum c a p a c i t y of t h e

landfill. These data are used to determine the length of

time the landfill will accept waste.

T h e r e are two important variables used in th2 LAEEM. The

first is the methane generation potential of the waste , L,.

This parameter can be determined e i t h e r by field tests or

based on data £rom other landfills since it is primarily

dependent on the types of waçte present. The second variable

is the methane generation rate constant, k- This variable

determines how quickly the methane generation rate will

decrease after it has reached its peak. This variable is

much more site specific t h a n L,, since it depends on

landfill conditions such as moisture content, pH and

temperature.

The LAEEM allows the user to enter site specific values for

k and Lo or allows for two default settings for these

variables to be chosen. The first of the default settings is

the Clean Air Act (CAA) defauit values. T h e s e values are

d e s i g n e d to e s t i m a t e the maximum amount of landfill gas that

c o u l d be expected from the l a n d f i l l . The primary use of

these default values is to determine if landfill gas control

measures are required a s set out i n t h e CAA. The second set

of default v a l u e s a r e derived f r o m t h e U.S. EPA's

"Compilation of Air Pollutant Emission Factors, AP-42" which

was compiled by the U.S. EPA in 1997. These default v a l u e s

are d e r i v e d from actual l a n d f i l l s and provide estimates of

landfiil gas emissions that are e x p e c t e d to be closer to

actual values .

Once al1 of the data have been input into the LAEEM, t h e

mode1 determines t h e amount of rnethane g e n e r a t e d by a given

quantity of w a s t e oves t i m e w i t h i n a landfill f o r each year.

The LAEEM then determines the amount of carbon dioxide

generated by assuming that the g e n e r a t e d landfill gas is 50%

methane and 5 0 % carbon dioxide. This ratio can be changed if

site conditions warrant. In orde r t o d e t e r m i n e the emission

of other trace gases, such as V O C s , the LAEEM relies on

c o m p o s i t i o n a l a v e r a g e s obtained from a numùer of landfills.

S i t e specific values cari also be used for these inputs.

I n the case of t h e Regina landfill, there is a l a c k of s i t e

specific da ta . T h i s required that the LAEEM be run under a

variety of conditions and assumptions. Some of these

assumptions were t h e compaction rate for the waste, waste

a c c e p t a n c e rates b e f o r e 1 9 8 0 , t h e amount o f b i o d e g r a d a b l e

w a s t e p r e s e n t i n t h e l a n d f i l l and t h e ratio o f t h e l a n d f i l l

gases p r o d u c e d .

Even though t h e LAEEM is a v e r y s imple model, i t i s deemed

a c c u r a t e fo r u s e by t h e U.S. EPA and s e v e r a l p r o v i n c e s i n

Canada, Studies have shown t h a t t h e S c h o l l Canyon Mode1

prov ides results t h a t are comparable to those f rom o the r

rnodels, i n c l u d i n g more c o m p l i c a t e d rnodels (Peer e t al.,

1993; Oonk e t a l . , 1 9 9 4 ) . F i r s t o r d e r rnodels that a r e

p r o p e r l y calibrated have been shown t o be able t o a c h i e v e

r e s u l t s t h a t a r e &IO% of a c t u a l emissions ( Z i s o n , 1 9 9 0 ) .

Because of t h e limited accuracy of most l a n d f i l l d a t a , i t is

l i k e l y t h a t rnore c o m p l i c a t e d models may n o t be a b l e t o

p roduce more a c c u r a t e r e s u l t s . Because several p r o v i n c e s and

t h e U.S. EPA use the LAEEM, t h e r e s u l t s can be compared w i t h

t h e results f rom o t h e r l a n d f i l l s .

4 . 7 Supplemental D a t a

I n o r d e r t o u n d e r s t a n d t h e emissions data f rom t h e Regina

l a n d f i l l , a d d i t i o n a l da ta were r e q u i r e d i n c l u d i n g

i n f o r m a t i o n on t h e t y p e s , a g e s and q u a n t i t i e s of waste a t

the l a n d f i l l , and t h e yearly acceptance rates f o r va r ious

types of w a s t e . It was i m p o r t a n t that, i n terms of

u n d e r s t a n d i n g any s p a t i a l v a r i a n c e o f e m i s s i o n s a t t h e

landfill, the characteristics of the waste at a particular

location were known.

A careful review of relevant reports and background

information on the landfill was carried out. Because written

records on the landfill are incomplete, it was also

necessary to conduct interviews with City of Regina

employees w h o have first hand knowledge of the landfill.

This included taiking to engineers at the City of Regina and

operators at the landfill.

In order to determine how the emissions f rom the Regina

l a n d f i l l compare with other similar landfills, information

sharing took place with the City of Saskatoon. Saskatoon's

landfill is quite similar to Regina's in terms of types of

waste in place and regional climate. The University of

Regina helped plan and organize a detailed landfill gas

study for the Saskatoon Landfill, similar to the one

conducted at the Regina Fleet Street Landfill. This included

help in developing a survey of the landfill and in defining

a sampling area.

In addition to the information from the Saskatoon Landfill,

information on emissions from landfills collected by

Environment Canada was obtained for comparison purposes.

5.0 F i e l d S t u d y S i t e s

5.1 T h e Regina F l e e t Street Landfill

T h e Regina F l e e t S t r e e t L a n d f i l l was opened i n 1 9 6 1 a f t e r

the closure of the p r e v i o u s l a n d f i l l l o c a t e d a t Mount

P l e a s a n t . T h e l a n d f i l l i s situated a t t h e northeast c o r n e r

of Regina o n F l e e t S t r e e t 0 . 5 km n o r t h o f 9th Avenue. The

l a n d f i l l o c c u p i e s a t o t a l a r e a of 97 h e c t a r e s w i t h actual

l a n d f i l l activities a c c o u n t i n g for a p p r o x i m a t e l y 60 h e c t a r e s

of that total a r e a , and r i s e s to a height of o v e r 30 m. The

l a n d f i l l s t a r t e d o p e r a t i o n a t t h e s o u t h w e s t c o r n e r of the

s i t e and l a t e r ex tended e a s t and t h e n n o r t h . The l a n d f i l l

was constructed w i t h no l i n e r and a t p r e s e n t , t h e r e i s no

l e a c h a t e o r g a s c o l l e c t i o n system i n place.

T h e area of Regina i s deemed a r i d t o s e m i - a r i d . T h e mean

precipitation i n t h e Regina a rea is 400 mm. Of the 4 0 0 mm o f

p r e c i p i t a t i o n , 75% cornes in t h e fo rm o f r a i n f a l l . The

p r e c i p i t a t i o n that f a l l s i n Regina i s c o n v e r t e d i n t o 50%

e v a p o r a t i o n , 32% r u n o f f and 18% p e r c o l a t i o n ( R e i d Crowther &

Partners L i m i t e d , 1993)-

T h e Reg ina topography , including t h e l a n d f i l l a r e a , i s

generally f l a t w i t h low r o l l i n g hills. Regina's e l e v a t i o n

averages 590 m above sea l eve l w i t h t h e l a n d f i l l located a t

approximately 600 m above sea l e v e l . T h e Regina Fleet Street

L a n d f i l l subsurface is cornposed of c l a y u n d e r l a i n b y s i l t

t h a t ex t ends to a depth of 3 .5 to 6 . 5 m below t h e ground

surface, with an increase i n silt c o n t e n t , l a y e r i n g and

f r a c t u r i n g a s t h e depth increaseç (Reid Crowther & Par t f iers

Limited, 1 9 9 3 ) . The subsu r f ace m a t e r i a l i s t y p i c a l of the

m a t e r i a l found throughout t h e Regina area.

Both the Condie (A-Zone) Aquifer and the Regina (8-Zone)

Aquifer a r e located below t h e l a n d f i l l . T h e Condie A q u i f e r

format ion is 1 0 t o 25 rn t h i c k and is 3 to 7 m below t h e

l a n d f i l l site. The Regina A q u i f e r formation i s 4 to 40 m

t h i c k and is located 23 to 50 m below t h e landfill (Reid

Crowther 6 P a r t n e r s Limited, 1 9 9 3 ) .

T h e Regina F l e e t Street L a n d f i l l i n i t i a l l y employed t h e

trench rnethod of waste disposal. This method involves

f i l l i n g excava ted trenches with waste and then covering

t h o s e t r e n c h e s with cover m a t e r i a l . L a t e r , landfill

o p e r a t i o n s switched t o the area method of l a n d f i l l i n g which

con t inues t o t h i s day over t o p of the o l d t r e n c h e s .

T h e waste accepted a t the landfill for the majority of its

h i s t o r y h a s c o n s i s t e d p r i m a r i l y of residential and

commercial waste, f o r example garbage, yard waste, paper,

plastic, metals, wood, glass and assorted rubble. The exact

types and quantities o f waste brought to the landfill in the

early years are unknown due to a lack of accurate record

keeping. I t is only from 1980 to the present that records

are available on tne waste brought to the landfill. Several

efforts have been made to estimate the t o t a l quantity of

waste present in the landfill. By using these estimates, it

is possible to work backwards from what is known now, and

make rough estimates of the acceptance rate of waste a t the

landfill i n the past. Discussions with City of Regina

employees allowed fo r the development of a map, Figure 5.1,

indicating the believed ages and locations of waste at the

landfill.

In addition to the solid waste that has been brought to the

landfill, liquid waste, including waste oil, and wastewater

sludge have a l s o been disposed of at v a r i o u s times. L i q u i d

waste was deposited at various locations on the landfill i n

pits that were 4 to 5 m in depth. This practice was stopped

because of potential groundwater contamination concerns.

Wastewater sludge was primarily deposited on the top of the

landfill and rnixed with surface material.

In addition to waste coming d i r e c t l y from generators, some

waste has corne from both a waste incinerator and a waste

shredder. An incinerator was constructed in 1951 with an

operating c a p a c i t y of approximately 5.4 tonnedhour. With an

average working day of 16 hours the incinerator could

incinerate close to 86 tonnes every day. In 1961, the

incinerator was expanded and t h e c a p a c i t y was i n c r e a s e d t o

approximately 9 tonnes/hour which meant t h a t 1 4 4 tonnes

could be incinerated every day. In the late 1960's and early

1970rç, pollution control requirements greatly reduced its

capacity. In 1975, a garbage shredder began operation with a

capacity of almost 27 tonnes/hour or 45,000 tonnedyear. The

shredder was capable of reducing the size of the waste to 75

mm in size or less. The waste shredder operated until 1986.

A summary list of the types and quantities of waste brought

to the landfill from 1980 to 1997 c m be seen i n Table 5.1.

A high percentage of waste landfilled at the Regina Fleet

Street Landfill has been rubble. There has been a decrease

over time in t h e ratio of rubble to waste landfilled, due in

part to waste diversion and recycling programs. The high

amount of rubble (asphalt and concrete), which does not

g e n e r a t e landfill gas, occupies a large volume in the

landfill and must be taken into account when using landfill

gas models or making interpretations of field data.

5 - 2 T h e Saskatoon Landfil1

The Saskatoon Landfill was opened on August 16, 1955 on l a n d

previously used f o r farming. The Saskatoon Landfill is

located i n the southwest corner of the City of Saskatoon. To

the West of t h e landfil1 is a Saskatchewan Government power

station and to the north are railway tracks. P a s t the train

tracks to t h e north lies a City of Saskatoon golf course. To

the south and east of the landfill runs the South

Saskatchewan River; this river is a primary f e a t u r e of the

City of Saska toon . A map of the Saskatoon Landfill can be

seen in Figure 5.2.

The Saskatoon Landfill is composed of a north cell, opened

in 1955 and closed in 1996, and a south ce l l , opened in

1996. The Saskatoon Landfill is the major waste disposa1

site for the City of Saskatoon and r e c e i v e s primarily

municipal and some indusirial waste. Compared to the Regina

Fleet Street L a n d f i l l , little rubb le i s landfilled due to

its use in various river bank projects. I n t h e p a s t , t h i s

site has received l i q u i d waste of various types and

q u a n t i t i e s . Waste oil was received and disposed of a t t h e

site, in separate disposal pits, up until 1980 at which time

this prac t ice was

F i g u r e 5.2 - T h e Saskatoon Landfill Study A r e a .

discontinued. Feedlot manure was also deposited at the

Saskatoon Landfill for a large number of years. The rnanure

was separated and stockpiled on the north side of the

landfill.

The Saskatoon Landfill slopes towards the South Saskatchewan

River. The top layers of material under the landfill consist

of sand, silt and clay. Below these layers lie approximately

50 m of till which overlies bedrock, silt and sand.

The north ce l l , the study area, of the landfill is

approximately 40 years old, 35 m in height, with an area of

roughly 20 hectares and a volume of approximately 3,200,900

m3. The average density of the waste is believed to be

approximately 641 kg/m3, which gives a total mass of waste

in the study area of approximately 2,000,000 tonnes

(Casavant, 1998) .

7 0

6.0 Results of the Landfill Investigations

6.1 Regina F l e e t Street L a n d f i l l Waste Sampling

Sorne on site analyses on t h e waste took place d u r i n g

sampling. The boreholes and the test pit were logged to give

an indication of the types and ages of material f o u n d at

various d e p t h s . In addition t o the borehole logs,

temperatures were also recorded, but due t o improper d a t a

collection, temperatures were not recorded for al1 d e p t h s .

Basic analysis of al1 waste samples, carried out by the SRC,

i n c l u d e d tests for chloride, sodium, organic carbon and

arnmonia as nitrogen. Other tests determined the chemical

o x y g e n demand (COD), moisture content, loss of ignition,

total dissolved solids (TDS) and pH.

D e t a i l e d analysis was conducted on a select number of

samples. A plate count was completed, which gives an

indication of the number of microorganisms present in the

waste sample and can be used as an indication of microbial

activity. The waste was also analyzed for thirty inorganic

substances including heavy metals, such as mercury and lead,

and key n u t r i e n t s , such a s phosphorus a n d potassium.

Finally, 26 organic compounds were tested for including

benzene, toluene and xylene.

The f i r s t b o r e h o l e , Borehole#l, was drilled 21.5 m i n t o t h e

landfill. The results of the basic laboratory analysis

c o n d u c t e d on the samples from B o r e h o l e # l can be found in

Table 6 . 1 .

Table 6.1 - Data f r o m t h e b a s i c laboratory analysis fo r Borehole#l.

A summary of the results for a sub-set of parameters of t h e

deta i led laboratory a n a l y s i s conducted on select samples

f rom Borehole#l can be found i n Table 6.2.

Depth

S u r f a c e 2 3 4 5 7 8 9 10 12 13 14 15 17 18 f9 20 21

Average

pH

7.99 8.24 '

8 .O6 7.93 7 -28 7 - 7 1 8.06 6.37 8.40 7.95 8-41 8.07 7-30 7-94 8.10 7.99 8-35 7 - 3 4 7.56

Moisture Content (%)

16.10 19.50 23.50 21.40 23-90 26.90 20.90 49.20 18.20 15.90 17.10 38.20 33.10 20.50 16.00 20.00 24.40 18-2 22.26

Ammonia as N i t r o g e n

( m g m 0.21 , 1.3 3.4 3.0 9.2 11

Temp. (OC)

n / a n / a n / a n / a n/a n / a

Organic Carbon (mg/L) 6.0 7.3 9.4 94 250 90

n/a n / a n / a n / a n / a n / a n / a n / a 12 1 5 17 25

17.25

3 3 1 14 65 17 46 61 38 170 49

24 11 7.3 7.2 5.9 4.9

- 5.1 5 7 34 34 n/a

55.83

3.9 6-2 2.6 n / a 6.33

Table 6.2 - Detailed laboratory analysis for select samples from Borehole#l.

- - - - -

Note: ct - count

Depth (m)

1

1 6 11 16 21

Ava .

The second borehole, Borehole#2, was drilled next to

Borehole#l and extended to a depth of 11 m. Temperature and

borehole l o g g i n g took place for Borehole#2 but laboratory

analysis was not conducted. Temperature data for Borehole#2

c a n be seen in Table 6.3.

Table 6.3 - Temperatures from Borehole#2.

Plate Count kt*/@

6300000 3400000 800000 300000 10000000 4800000

A I

10.7 17 . 6 . Average 12.88

The Test Pit was excavated to a depth of 5 rn into the

Organic Carbon bg/W

3 15 37 81 13

24.83

landfill. The results of basic laboratory analysis on the

naste from the Test Pit can be seen in Table 6 . 4 .

Ammonia as N i t r o g e n

bg/W 0.58 15 4.2 4.7 8.5 5.5

Phosphorous (mg/L)

<0.05 O. 1 ~0.05 C0.05 O. 093 CO ,069

Lead (mg/L)

O. 003 <0.002 <0.002 C0.002 0.005

Wrcury (mg/L)

0.11 ~0.05 C0.05 c0.05 C0.05

Table 6 . 4 - Data from basic laboratory analysis for the Test P i t .

6 .2 Regina F l e e t S t z e e t Landfil1 Pteliminaty Landfil1 Gas S t u d y

DePa

1 2 3 4 5

Average

The p re l i rn inary FID gas study was conducted over

approximately a one week period during the surnmer of 1997.

The study began on July 7=" and ended on July 16'". L a n d f i l l

gas samples were not collected during tirnes of high wind o r

rain, as these cond i t i ons would interfere with proper gas

collection. Al1 but 119, o r approxirnately 173, of t h e 679

potential sampling locations were sampled. A complete list

of FID results from the Regina Fleet Street Landfill can be

seen in Appendix A.

A number of samples, 31 i n total, were collected away from

planned sampling locations at locations that had high

e m i s s i o n s i d e n t i f i e d while walking between planned sampling

locations. The results of the FID gas survey can be seen in

Figure 6.1.

PH Moisture Content (%)

Temp. (OC)

9 8.7 7 . 4 10.6 11

9 . 3 4

Organic Carbon mgm 320 190 5 4 0 94 0 1230

536.67

7.36 7.26 7.1 6.73 6.09 6.91

Ammonia as Ni trogen

(mg/fi) 18 7.1 31 50 4 8

25.68

18.93 16.2 25.1 33.8 43.5

- -

- 22.92

6.3 Saskatoon Lanàfill and Regina F l e e t S t t e e t Landfill S h a l l o w Gas Well D a t a

Two s h a l l o w gas wells, a s described in Chapter 4 , were

installed a t t h e southwest and southeast corners of the

Regina Fleet Street Landfill. Four s imilar wells were

installed at the Saskatoon Landfill. The gas collected from

the wells was sent to ERMD for analysis. The gas was

analyzed for 144 substances. The results for al1 144

substances for the Regina Fleet Street Landfill can be seen

in Appendix B.

Because the impacts of al1 144 substances are not yet known,

only a srnall number are examined here. For the purposes of

cornparison between the Regina and Saskatoon Landfills, 18

substances were looked at. These 1 8 substances were chosen

because they are narned i n t h e Canadian Environmental

Protection Act (CEPA) (Canada Gazet te , Part 1, February 11,

1989) as priority substances. In addition to these priority

substances, vinyl chloride, a known toxic substance (TS),

and a nurnber of ozone d e p l e t i n g substances (ODS) were also

exarnined. The results from the Regina Fleet Street Landfill

can be seen in Table 6.5.

Table 6.5 - VOC concentrations ( p g / m 3 ) frorn shallow gas wells at the Regina Fleet Street Landfill.

I compounds SW Well (pg/m3) 1 SE ~ e l l ( p g / m 3 ) 1

Vinyl Chloride l 967 14348 I Freon 12 918 17229

Freon 22 4539 16768

Freon 113 1 15 1 1421 1

I 1

Total 1 7033 1 55466 1 Freon 114

I I P r i o r i t y Substances

5 92 1778

m/ p-Xylene

Benzene

1 1

Toluene 3259 5 4 4 3 3 1 1 I

39774

4 660

Trichloroethene

79727

2706

153 I 3272

f I

I Tetrachloroethene

1 1

t 1

Total (144 compounds) 1 446185 1302598 1

Dichloromethane

I

1 185

Total (18 compounds)

The r e s u l t s of t h e VOC t e s t i n g for the Saskatoon L a n d f i l l

can be seen in Table 6.6.

6172

I 309

66448 I 347374

% of Total

129040

I 14.9 26-3

Table 6.6 - VOC Concentrations (pg /m3) from four s h a l l o w gas wells at the Saskatoon Landfill.

Vinyl C h l o r i d e 1701 18320 164 535

Freon I I 68 744 O 69993

F reon 12 1072 17747 790 22831

Freon 22 12732 1 3 0 1 6 3713 5978

Freon 113 33 152 4 3 878

F reon 114 169 2636 208 578

To ta1 15775 52615 4918 100793 I I

P r i o r i t y Substances

O-Xylene 2012 10463 1 5 6 1323

m/p-Xylene 7697 31312 739 6022

Benzene 801 5453 9435 68 9 1 f 1 1

T r i c h l o r o e t h e n e 1869 1 220 9 i 0 1 I 162 1 1 1 1

Toluene 1 30985 ( 72928 1 485 1 79076 I I I I

T e t r a c h l o r o e t h e n e 891 6223 1 4 3 401 1 1 1 1

Dich lo rome thane I 3356 1 1366 860 1 25458

1,2,4-Trichlorobenzene O O O O

T o t a l 1 47611 130410 9458 113131

T o t a l (18 compounds) 63386 103026 14376 213924 1 f I I

Total (144 compounds) 1 390932 1 570941 1 2374075 1 880934 1 1 1 l

% of Total 16.2 1 32.1 0.61 24.3

T h e VOCs can aiso be placed in groups with cornmon attributes

for ana lys i s : freons which a r e known ozone depleting

substances; benzene, toluene, ethylbenzene and O-m-p xylenes

abbreviated as BTEX; and vinyl chloride. Concentrations of

these groups from t h e Regina Fleet Street Landfill c a n be

s e e n in Table 6.7. These sub-categories were c h o s e n because

they are the same ones examined by ERMD, thus allowing for

cornparisons t o be made.

T a b l e 6.7 - Summary of VOC c o n c e n t r a t i o n da ta from the Regina Fleet Street Landfill.

Compounds

Freons 1 0.006 1 0.041 1 0.004-0.041 1 BTEX

SW Well-Aug . 22, 1997

(g/m3)

The results from the S a s k a t o o n Landfill and previous ERMD

O. 108

Vinyl Chloride

studies for the v a r i o u s sub-categories can be seen in Table

SE Well-Aug. 22, 1997

(g/m3)

Table 6.8 - Surnmary of VOC concentration data £rom the Saskatoon Landfill.

ERMD Ranges

( d m 3 )

0.186

0.00097

0.056-0.59

I BTEX I 0.046 I C.133 I 0.018 I 0,090 I 0.056-0.59 I

0.0143

Compounds

0,001-0.041

Well#l ( d m 3 )

Freons

Vinyl Chloride

We11#2 ( d m 3 r

O. 014

0.0013

WellQ3 (da3 r

0.034

0,018

Wellf 4 ( d m 3 I

0.005

0 00016

ERMD Ehnges ( d m 3 )

O. 100

0-00054

0.004-0,041

0.001-0.041

6 . 4 R e g i n a F l e e t S t r e e t Landfill Gas Modeling Results

The LAEEM was used to model the amount of landfill gas being

generated from the Regina Fleet Street Landfill. The

modeling was done to help validate the field data and vice

versa .

The model was run a number of tirnes with different input

parameter values. The parameters that were changed in the

various simulations were the values of k and L,, the waste

in place value for 1997, and the ratio of rnethane to carbon

dioxide in the landfill gas. The remaining parameters

remained the same for al1 of the simuLations.

The waste acceptance rates o v e r the period 1981 to 1997 were

known from landfill records and can be seen in Table 6.9.

The waste acceptance rates for the years prior to 1981 were

estlmated by subtracting the total accepted waste for 1981

to 1997 from the estimated waste in place in 1997 to get the

waste in place for 1980. Due to the uncertainty of certain

data, two estimates were made of the waste in place i n 1997,

6.5 million tomes and 7 million tonnes. The estimate of 7

million tonnes is believed to be more accurate based on p a s t

acceptance rates and landfill surveys. The estirnate for the

waste in place for 1980 allowed t h e LAEEM t o automatically

calculate the amount of waste accepted in the years from

1961 to 1980.

Table 6 .9 : Amounts of waste landfilled from 1 9 8 1 t o 1997IReid Crowther & Partners, 1995; and landfill commodity reports).

The final landfill capacity had to be estimated in orde r to

Y e a r

1981 1982 1983 1984 1985

determine the l i f e span of the landfill. This estimate was

based on the final landfill design proposed by Reid Crowther

Tomes of Rubble Landfilled

101481 124414 100488 94750 74000

& Partners Ltd. (1995), and a two hi11 landfill, the design

favored by the City of Regina. Futu re landfill acceptance

231961 244116 214073 206262 181767 174418 159001 146631 144032 14 1772 149568 175197

3375658

Tonnes of Garbage Landfilleci

132076 135440 150275 141690 15224 6

2

ra tes were assumed to remain r e l a t i v e l y constant. These

Total Tonnes Landfilled

233557 259854 250763 236440 226246

assumptions allow f o r a final landfill capacity of 9,006,000

1986 1987 1988 1989 1990 1991 1992 1993 19 94 1995 1996 1997

Total

tonnes.

83313 92258 71721 59727 44975 45542 38682 21033 15652 13803 20691 35818

1038348

148648 151858 142352 146535 136792 128876 120319 125598 128380 127969 128877 139379

2337310

The two key parameters that varied between simulations were

k and La. Both of the LAEEM default settings, CAA for arid

conditions and AP-42 for arid conditions, were used in

various simulations. The CAA default setting, k=0.02 l/year

and L,=170 ~n~/~ear, were used to examine emissions from a

regulatory perspective to determine if landfill gas control

measures would be required for the Regina Fleet Street

Landfiil based on U.S. EPA regulations. The AP-42 default

settings, k=O .O2 l/year and Lo=lOO m3/year, were used to

provide a more accurate estimate of emissions. The final set

of k and L, values, k=0 .O06 l/year and L,=170 m3/year, were

obtained from an Environment Canada report for rnodeling

landfills in Canada (Environment Canada, 1 9 9 7 a ) . The tables

containing the Environment Canada values of k and La for a l 1

the provinces in Canada can be seen in Appendix C.

The f i n a l parameter that varied between simulations was the

volumetric ratio of methane to carbon dioxide. The LAEEM

assumes a ratio for methane to carbon dioxide of 5 0 ~ 5 0 . The

Regina Fleet Street Landfill field data showed a ratio of

methane to carbon dioxide of 4 1 5 9 , which is most likely a

transitional ratio and will likely reach 50:SO over time.

Both ratios were used in various simulations.

The default parameters and the assumptions used in running

the various simulations can be seen in Table 6.10.

Table 6.10 - Parameters and assumptions used in landfill gas simulations.

D e f a u l t Parameters

CAA Defaul t ( A r i d ) L o = 170 m3/year k = 0.02 l / y e a r

AP-42 Defaul t ( A r i d ) Lo = 100 m3/year k = 0 .02 I / y e a r

Env. Canada Defaul t

Waste In Place i n 1997

6 .5 Mi l l i on Tonnes

6.5 Mi l l i on Tonnes

k = 0.006 l/;ear CAA Defau l t (Ar id )

R a t i o of CH, to CO2 in

Landfil1 Cas b CH4 = 50 cf CO2 = 50

1 CH4 = 50 S CO- = 50

6.5 Mi l l i on Tonnes

L o = 270 m3/year k = 0.02 l / y e a r

AP-42 Defaul t ( A r i d ) Lo = 100 m3/year k = 0 .02 I/year

Fnv. Canada Defaul t Lo = 170 m3/year K = 0.006 l / y e a r

CAA Defaul t (Arid) Lo = 170 m3/year

% CH4 = 50

6.5 Mi l l i on Tonnes

k = 0.02 l / y e a r AP-42 Defau l t (Ar id )

Lo = 100 m3/year

% CH4 = 4 1

6 . 5 Mil l i on Tonnes

6.5 Mi l l i on Tonnes

7 Mi l l i on Tonnes

k = 0 .02 l/year Env. Canada Defaul t

The results from the various simulations can be seen in

Table 6.11.

Ir CO2 = 59

a CH4 = 4 1 Cs CO2 = 59

8 CH4 = 4 1 8 CO2 = 59

%CH4 = 50 % C O 7 = 50

7 Mi l l i on Tonnes

7 Mi l l i on Tonnes 1 I

S CH4 = 50 Lo = 170 m3/year k = 0.006 l / y e a r CAA Default ( F z i d ) Lo = 170 m3/year k = 0.02 l/year

?iP-42 Default(Arid) Lo = 100 m3/year k = 0.02 l/year

Env. Canada Defaul t Lo = 170 m3/year k = 0.006 l/vear

% CH4 = 50 % CO2 = 50

7 Mi l l i on Tonnes

7 Mi l l i on Tonnes

7 Mi l l i on Tonnes

% CO2 = 50

B CH4 = 4 1 % CO2 = 59

8 CH, = 41 % CO7 = 59

% CH, = 4 1 % CO2 = 59

Table 6.11 - Results of landfill gas modeling.

1 Simulation # 1 Methane 1 Catbon Dioxide (

6 . 5 Saskatoon Landfill and R e g i n a Fleet S t r e e t Lanüfill Detailed Gas Study

A total of 230 emission samples were t a k e n at t h e Saska toon

L a n d f i l l over t h e surface of the n o r t h ce l l u s i n g a f l u x

chamber. The sampling was completed dusing the late

summer/early fa11 of 1997. A map showing the sampling

locations and the results of the emissions sampling can

seen in Appendix D.

The locations and quantities of methane and carbon dioxide

emissions f r o m the Saskatoon Landfill can be s e e n in Figures

6.2 and 6.3,

A summary of the c o l l e c t e d data concerning t h e quantity and

composition of the gas emitted from t h e Saskatoon L a n d f i l l

can be seen i n T a b l e 6 . 1 2 . The yearly emission rate for the

Saskatoon L a n d f i l l was c a l c u l a t e d b y assuming that the t o t a l

ernission ra te , determined at the tirne o f testing, was a n

average f o r t h e ent i re year.

Table 6 . 1 2 - Data from the Saskatoon L a n d f i l l Gas Study.

Component

Methane

Information on the maximum, minimum and a v e r a g e emissions

found a t the Saskatoon L a n d f i l l can be s e e n in Table 6.13.

Emission Rate (L/hom)

I 1 I

Table 6.13 - Emission rates from the Saskatoon L a n d f i l l Gas Study.

591663.75

Carbon Dioxide

1 Cornponant 1 Murinium Emission 1 Maximum Emissaon 1 Averaue Emission 1

Composition of Landfill Gas, 8

Annual Landfill Gas Release

37.5

985406.25

( tonnes/year) 3176

62.5

1 Rate (~/hour/m')

15146

Rate Whour/m2) 210.7 Methane

I

Rata <~/hour/m') 2.7 O

180.1 Csrbon Dioxide 4.6 0.2

A t the Regina Fleet Street Landfill a total of 675 emission

samples were taken covering 63.2 ha of the landfill site. A

flux chamber was used to collect landfill gas samples. The

samples were taken during the summer of 1997 beginning on

August 19 and ending on September 5. A table containing the

complete list of collected data can be seen in Appendix E.

Maps showing the locations of methane and carbon dioxide

emissions can be seen in Figures 6.4 and 6.5.

fnformation on the quantity and composition of the gas

released from the Regina Fleet Street Landfill can be seen

in Table 6.14. The year ly ernission rate for the Regina Fleet

Street Landfill was calculated by assuming that the total

emission ra te , determined at the time of testing, was an

average for the entire year.

Table 6.14 - Data from the Regina Fleet Street Landfill Gas Study.

Component

Methane

Emission Rate (L/hou)

Carbon Dioxide

1536975

Composition of L a n d f i l 1 Gas, %

Annual L a n d f i l l Gas W e a s e

41.5

34353 I

(tomes/year) 8842

2174850 58.5

F i g u r e 6.4 - Methane emissions a t the Regina Fleet Street Landfill (Original in co lor ) .

Table 6.15 shows additional information on the minimum,

maximum and average emissions from the Regina F l e e t Street

Landfill.

Table 6 . 1 5 - Emission r a t e s from t h e Regina Fleet S t r e e t L a n d f i l l Gas S t u d y .

1 Componen t 1 Minimum Emission 1 Maximum Emission 1 Average Emission

Methane

Carbon Dioxide

R a t e (~/hour/m') O. O

O. O

Rate Whour/m2) 198.24

Rate (~/hour/m') 2.53

130.82 3.58

7 . 0 Discussion of Landfill Investigation Resul ts

7.1 Interna1 Landfill Conditions

D a t a from two boreholes and a test pit indicate how well

Regina Fleet Street Landfill conditions reflect what is

deemed optimal for landfill gas generation. In terms of pH,

where the optimal range is 6.8 to 7.4 (Barlaz et al., 1990),

the average from Borehole#l was 7.5 and £rom the Test Pit

was 6.9. The pH from the Test Fit was in the optimal range

for landfill gas generation and should not hinder its

generation. The pH from Borehole#l is close to the average

for landfills in the later stages of landfill gas generation

(Barlaz et al., 1990) .

The temperature averages for the Regina Fleet Street

Landfill were well outside of the optimal ranges of 32 to

3 5 a ~ or 45 to 50°c (El-Fade1 et al., 1996) for landfill gas

generation. The temperatures at shallow depths averaged

12.g0c for Borehole#2 and only 9.3OC for the Test Fit.

Temperatures taken closer to the surface of the landfill are

more sensitive to atmospheric temperatures, and t h e samples

were collected in early winter. Even at greater depths in

Borehole#l. below 20 rn, the temperatures averaged only

17.3OC. Since temperatures were taken once the waste had

been removed from the borehole the recorded temperatures m a y

have been slightly lowered due to ambient conditions.

Temperature m a y be p i a y i n g a very important role in the rate

of landfill gas generation. Because low temperatures are

experienced for extended periods of tirne i n Regina, l a n d f i l l

gas generation may be lower during these months,

particularly in the upper parts of the landfill that are

most affected by atmospheric temperature changes. Emissions

will also be reduced during these months due to frozen s o i 1

conditions. This w i l l lower the total yearly generation and

emission rates. Because the analysis used summer emissions

as the b a s i s for a yearly emission or generation rate

estimate, the yearly rate m a y have been overestimated.

It has been stated earlier that the rate of landfill gas

generation increases significantly as the moisture c o n t e n t

reaches field capacity, 45 to 60% (Environment Canada,

1991), and then increases slightly as the moisture content

increases to 80% (Gardner and P r o b e r t , 1992; Munasinghe and

Atwater, 1985). The m a j o r l t y of l a n d f i l l s i n N o r t h America

average between 20% and 30% at t h e time of placement

(Gardner and P r o b e r t , 1992) . The Regina Flee t Street

Landfill, based on samples from one borehole, had an average

moisture content of approximately 22%. The low moisture

content is not surprising considering the very dry

conditions present in the Regina a r e a . The low moisture

content will reduce the rate a t w h i c h landfill gas will be

produced ,

In addition to moisture content, pH and temperature, there

are optirnal l eve l s for nutrients and other chemicals for

landfill gas generation. One of the key nutrient factors is

the carbonhitrogen ratio in the waste. In most landfills,

this ratio is 30:l (Gardner and Probert, 1992); in this

landfill, it was 21:l in the Test Pit, but only 9:l in

Borehole#l. Low ratios could indicate lower rates of

landfill gas generation at the Regina Fleet Street Landfill.

Low ratios could also indicate that waste decomposition has

occurred in the older sections of the landfill.

The results of the plate count tests indicate that there

were greater numbers of microorganisms in the landfill near

the t op and bottom. The presence of microorganisms at a l 1

leveis tested indicates that, even though some of the

landfill conditions are outside of optimal ranges, microbial

activity is caking place, landfill gas is being generated,

and the waste is being broken down, The fact that the

samples were t a k e n from an older portion of the landfill

could explain the pattern of microbe counts. The waste may

not have h a d sufficient quantities of nutrients to support

large numbers of microbes. The upper portions, the newer

waste, may have sufficient nutrients available for microbial

activity, hence t h e higher numbers of microbes. N u t r i e n t s

would t end t o be leached from upper parts of the landfifl

and accumulate in lower areas providing sufficient nutrients

for the microbes found t h e r e .

The moisture content of the l a n d f i l l waste could be

increased by increasing infiltration thxough the cover,

decreasing r u n - o f f , or by adding moisture t o the landfill. A

higher moisture content would increase decomposition,

landfill s e t t l i n g and landfill gas g e n e r a t i o n rates a t the

Regina Fleet Street Landfill. However, higher moisture

contents would also increase the potential for leachate

g e n e r a t i o n that could pose a risk to the local aquifers.

7 . 2 Combustible Vapour Concentrations

T h e m a j o r i t y of points sampled with the FID had low

concentrations. The few points that had high concentrations

were l o c a t e d primarily along t h e slopes of the landfill,

particularly the south and east slopes. The south slope had

the highest number of high concentration points and had the

highest individual FID readings. Very low concentrations

were found in areas that were w e l l compacted. The compacted

soi1 may have operated a s a barrier to lanàfill gas

emissions.

There were a number of visual observations made while

collecting the preliminary landfill gas samples. Locations

exhibiting high FID readings on the south slope were

generally marked by missing or dead vegetation indicating

the presence of landfill gas. Also, a majority of the

locations along the south slope with high FID readings were

located at or near large cracks in the landfill surface

which may have facilitated the emission of landfill gases.

Visual observations were only possible along the south slope

due to the presence of vegetation and the lack of landfill

activities on that slope which would have removed signs of

landfill gas emissions.

T h e data showed a high degree of variability in terms of

concentration levels between points, as illustrateci in

Figure 7.1. Concentration leveis at a few points far

exceeded the concentrations at other surrounding points.

Approximately 16% of the sampling points had concentrations

less than or equal to 1 ppm. It appears that landfill gas is

being channeled from large areas within the landfill to a

small number of points where it is emitted.

A - - - - - - -- - - > = - A

FID Readings vs. Collected Samples

Collected Samples

Figure 7.1 - Variablity in FID readings.

A r e l a t i v e l y small p e r c e n t a g e of concentration points, 3%,

accounted for 63% o f t h e total amount of combustible vapour

found, as shown i n Figure 7 . 2 .

% of Combustible Vapour From Points with Greater Than 100 PPM of Combustible Vapour

% of Combustible Vapour From 3% of the points with the Hgkst Concentrations

0 % of Combustible Vapour From Remaining 97% of Points

Figure 7.2 - Combustible vapour from the highest concentration points.

P o i n t s w i t h h i g h l a n d f i l l gas concentrations were not

necessarily surrounded by other points of high

concentrations. Concentrations seemed to be highly confined

to s p e c i f i c locations at the landfill.

Because the combustible vapour, and presumably the landfill

gas, concentrations were concentrated along the slopes, the

detailed landfill gas sampling was concentrated on the

slopes of the landfill. Fewer sarnples were taken along the

top of the landfill, which showed uniformly low EID readings

during the preliminary study.

7.3 VOC Concentrations

The results of VOC testing from other landfills in Canada,

a s provided b y ERMD, can be compared to the results from the

Regina and Saskatoon Landfills to give an indication of the

r e l a t i v e concentration levels. The reported BTEX

concentrations, as measured by EMRD (Environment Canada,

1997b), at a number of Ontario landfills were in the range

of 0.056 g/m3 to 0.59 g/m3. The concentrations a t the Regina

Flee t Street Landfill ranged from 0.108 g/m3 to 0.189 g /m3,

and at the Saskatoon Landfill t h e range was 0.018 g/m3 to

0.133 g/m3. The r e s u l t s from the two Saskatchewan l a n d f i l l s

ind icé i t e t h a t t h e levels for BTEX were in the low to m i d d l e

range based o n ERMD d a t a .

The measurements of vinyl chloride concentrations at Ontario

landfills studied by ERMD range from 0.001 g /m3 to 0.041

g/m3. The levels reported at the Regina Fleet Street

Landfill were 0.001 g/m3 (SW Well) and 0.014 9/m3 (SE Well) ,

and at the Saskatoon Landfill the range was 0.001 g/m3 to

0.018 g/m'. The vinyl chloride levels at both of the

Saskatchewan landfills were in the low to middle range based

on ERMD data.

The levels of freons reported by ERMD (Environment Canada,

1997b) at Ontario landfills were in t h e range of 0.004 g/m3

to 0.041 g / m 3 . The range of freons at the Regina Fleet

Street Landfill was 0.006 g /m3 to 0.041 g / m i and at the

Saskatoon Landfill the range was 0.005 g/m3 to 0.100 9/m3.

The freon levels reported at the Regina Fleet Street

Landfill span the total range of l e v e l s for a number of

landfills in Ontario and show a large degree of variance

between the southwest and southeast wells. The Saskatoon

Landfill had freon concentrations in one well that were more

t han double that reported at the R e g i n a Fleet Street

Landflll and at the Ontario landfills,

There are no specific regulations dealing with VOC emissions

from landfills in Canada. There are, however, limits set in

the Occupational Health and Safety Act (OHSA) for exposure

to various contaminants by workers. Two VOC concentrations

from the Regina Fleet Street Landfill and the Saskatoon

Landfill exceeded the limits set by OHSA; both happen to be

known carcinogens. Vinyl chloride concentrations at one w e l l

at each landfill, 14 mg/m3 at the Regina Landfill and 18

mg/m3 at the Saskatoon Landfill, exceeded the 10 mg/m3 OHSA

limit. Benzene levels exceeded the 0.300 mg/m3 OHSA limit at

al1 wells at both landfills and in some cases significantly

exceeded the limits, 4.6 and 2.7 mg/m3 a t the Regina

Landfill and 5 .4 and 6.4 mg/m3 at the Saskatoon Landfill.

The limits set by the OHSA are for an average exposure to

those contaminants for a typical 8 hour work day. While the

VOCs emitted from the landfill would be quickly diluted to

low levels upon reaching the surface, they may pose a risk

if landfill gas migrates to enclosed spaces on or off site

or if workers are exposed to direct emissions from the

landf ill.

While the levels reported at the Regina and Saskatoon

Landfills may appear high or l o w for various compounds, a

very small number of samples were obtained. For a small

sample set, there tends to be a higher degree of variance

between sampling l o c a t i o n s . A l so , a s i n g l e r e a d i n g c a n have

a l a r g e impac t o n the r e s u l t s . F o r example, the f r e o n l e v e l s

a t t h e two Saska tchewan l a n d f i l l s appear h i g h . The high

f r e o n r e a d i n g s c o u l d be due t o a number of i n f l u e n c i n g

f a c t o r s a t these p a r t i c u l a r l o c a t i o n s i n c l u d i n g t h e

d i s p o s a l , i n the area of t h e w e l l , of a s i n g l e source o f

f r e o n , such as any t y p e of c o o l i n g equipment . The f r e o n

l e v e l s would o n l y be a n a r e a o f concern i f s u b s e q u e n t

s amples a t o t h e r l o c a t i o n s a l s o show h i g h freon l e v e l s . I n

o r d e r t o d e t e r m i n e a more r e p r e s e n t a t i v e a v e r a g e for VOCs

from the Regina and Saska toon L a n d f i l l s , sampl ing from a

v a r i e t y o f d i f f e r e n t l o c a t i o n s a t t h e two l a n d f i l l s i s

r e q u i r e d .

7 . 4 Estimated Landfill Gas Generation Rate

Due t o a l a c k o f precise i n p u t d a t a , sorne mode l ing e r r o r is

t o b e e x p e c t e d . A s s t a t e d earlier e r r o r s o f k20 t o 30%

(Gardne r and P r o b e r t , 1992 ; Z i son , 1990) of a c t u a l values

a r e commonly found when s i m u l a t i o n s are c o n d u c t e d o n

l a n d f i l l s w i t h less t h a n perfect d a t a .

T h e mode1 s i m u l a t i o n of t h e Regina Landfill that most

closely matched t h e field s t u d y results of 8842 t o n n e s / y e a r

o f methane and 3 4 , 3 5 3 t o n n e d y e a r of carbon d i o x i d e , was

simulation lb, w i t h estimates of 11,170 tonnes/year of

methane and 30,650 tonnedyear of carbon dioxide. This

simulation was within 21% of the field study methane

emissions and 10% of the caxbon dioxide emission. This level

of error is similar to what has been reported for other

studies. It is also similar to the 10 to 15% error reported

by Saskatoon engineers in modeling their landfill (Casavant,

1998). The difference between the simulation results and the

actual field data is likely due to the LAEEM limitations,

and errors in the field results. Also, the LAEEM is designed

to estimate the amount of landfill gas generated within the

landfill while the field study measured landfill gas

emissions.

The CAA defaults, for arid c o n d i t i o n s , more closely

approximated the field results. The AP-42 default settings

use a lower L,. The low L, would tend to reduce the amount

of landfill gas t h a t would be generated by a given quantity

of waste, thereby lowering the amount of landfill gas

generated for a given landfill. As for the default values

specified by Environment Canada, the k value is much lower

than the one recornrnended by the U.S. EPA. T h e effect of the

low k value would be to lower the amount of landfill gas

that would be generated within a given landfill. In

addition, a summer generation and emission rate estimate was

a p p l i e d over the whole year , making the f i e l d results

perhaps more representative of maximum expected emissions.

As more data are collected on the landfill, the LAEEM

simulations c a n be further refined over time. T h e d e f a u l t

v a l u e s suggested i n t h e LAEEM for arid conditions appear to

be s u i t a b l e f o r simulating Saskatchewan landfills. However,

because there is a significant range of possible k and L,

default values, it is not known which ones will most

accurately mode1 Saskatchewan landfills. Various methods,

s u c h as U.S. EPA Method 2E or addltional emission studies,

can be used t o determine site specific values of these

v a r i a b l e s .

7 . 5 Spatial Variability

7.5.1 T h e Saskatoon Landfill

The emissions from the Saskatoon Landfill showed a high

degree of spatial v a r i a b i l i t y , The highest carbon dioxide

emission rate, 1 8 0 ~ / h o u r / m ~ , was more than d o u b l e the next

highest emission rate, 81.3 ~/hour /m* . For methane

emissions, the highest emission r a t e , 210 ~ /hour /m ' . was

more than t r i p l e t h e next highest recorded emission rate, 69

~ / h o u r / m ~ . A large number of locations'at the landfill

showed v e r y low e rn i s s ions , while o n l y a few a r e a s were

responsible f o r the m a j o r i t y of the total measured

e m i s s i o n s . The high o b s e r v e d emissions at a few l o c a t i o n s

c o u p l e d w i t h the low e m i s s i o n s a t t h e majority o f l o c a t i o n s

i n d i c a t e s t h a t v e n t i n g a t c e r t a i n l o c a t h n s on t h e l a n d f i l l

s u r f a c e was t a k i n g p l a c e .

T h e h i g h e rn i s s ions a t t h e Saska toon L a n d f i l l o c c u r r e d a l m o s t

e x c l u s i v e l y a l o n g t h e t o p p o r t i o n o f t h e s l o p e s o f t h e

l a n d f i l l . Only one l o c a t i o n of h i g h emissions was r e c o r d e d

away £rom t h e l a n d f i l l slopes. T h i s c o u l d be c a u s e d by t h e

g r e a t e r quantity and g r e a t e r compact ion of t h e c o v e r

m a t e r i a l t h a t would o c c u r on t h e top o f t h e l a n d f i l l .

L a n d f i l l gas, which would t e n d t o m i g r a t e v e r t i c a l l y , may b e

f o r c e d t o m i g r a t e h o r i z o n t a l l y u n t i l i t reaches a n a r e a

where i t can e s c a p e .

Carbon dioxide e m i s s i o n s over the surface of the S a s k a t o o n

L a n d f i l l were h i g h e r than methane emissions at t h e same

l o c a t i o n s . Because of t h e age o f t h e waste i n the l a n d f i l l ,

a c a r b o n d i u x i d e t o methane r a t i o close t o 50:50 would be

expected (McBean et a l . , 1 9 9 5 ) . The h i g h e r q u a n t i t y o f

c a r b o n dioxide found c o u l d be p a r t i a l l y d u e t o t h e o x i d a t i o n

of methane and other l a n d f i l l g a s e s a t the surface due to

the microbes present there. One of the by-products of this

consumption is carbon dioxide (Hettiaratchi, et al., 1996).

7 . 5 . 2 The Regina F l e e t Street Lanàfill

The spatial variability found at the Saskatoon Landfill is

similar to what was found at the Regina Fleet Street

Landfill. The detailed field investigation found highly

variable emissions across the entire landfill surface for

both methane and carbon dioxide. Variability was expected

due to the high degree of variability found during t h e

preliminary gas investigation. The degree of variability was

somewhat surprising in that the highest point emissions were

in some cases up to 80 times the landfill average. For

example, the highest methane ernission rate was 198 ~/hour/m~

while the landfill average for methane was only 2.53

~/hour/m'. And in the case of carbon dioxide, the h i g h e s t

emission rate was 103 ~/hour/rn', while the landfill average

was only 3.58 ~/hour/m'. Gas emissions in the detailed study

were concentrated along the slopes of the landfill, as found

in the preliminary study and at the Saskatoon Landfill. The

slopes accounted for the rnajority of emissions from the

Regina Fleet Street Landfill. The south, north and east

slopes combined to release more than 60% of the total carbon

dioxide and more than 70% of the total methane emissions

measured over the entire landfill. The emission patterns rnay

indicate problems with the integrity of the interim cover at

those locations. To better control emissions from both

landfills, additional cover material, or a collection and

control system may be needed along the slopes.

The south slope, which exhibited the highest concentrations

during the preliminary study also showed high point

emissions d u r i n g the detailed study. However, what was not

apparent during the preliminary study was that aside from

several points of very high emissions, the overall emissions

for the s o u t h slope were very low. The average gas emissions

on the south slope were only 2.13 I,/hour/rn2 for carbon

dioxide and 0.82 ~/hour/rn' for methane. Areas surrounding

points of high emission did not show similar high emissions.

The low emissions from the south slope can be partially

explained by examining the waste under this slope. The waste

under the south slope is some of the oldest at the landfill

with the majority dating back to the opening of the

landfill. It is known from past studies (Gardner and

Probert, 1992) that most waste reaches peak gas generation 3

to 15 years a f t e r being landfilled. The waste under the

south slope is probably past its peak generation period. The

high point source emissions along the south slope were not

likely due to high gas generation under the s o u t h slope, but

probably due to venting from other areas with a more

impermeable landfill cover.

W h i l e t h e highest point source methane emissions were found

along t h e south slope, the area showing the highest

concentration of methane emissions was the top half of the

e a s t slope, The e a s t slope had an average methane emission

r a t e of 6.47 ~/hour/m', which was close to 2.5 times t h e

average methane emission rate for the landfill- The e a s t

slope also had a carbon dioxide ernission rate of 7.39

~/hour/m', which was 2 times the landfill average. From

Figure 5 . 1 , it can be s e e n that t h e waste under t h e east

slope was deposited from 1989 to 1 9 9 3 . B e c a u s e the waste is

from 5 to 9 years old, it is in the early stages of peak

I m d f i l l gas generation (Gardner and Probert , 1992). T h i s

stage i s characterized by a leveling off of c a r b o n dioxide

emissions and increasing generation of methane. The ratio of

methane to carbon dioxide was close to 5 0 ~ 5 0 as would be

expected from waste of this age. It can be expected that as

the waste cont inues to age it will begin to produce greater

volumes of methane.

Whi le t h e h i g h e s t c o n c e n t r a t i o n o f methane was along t h e

n o r t h e r n p o r t i o n of t h e east s l o p e , t h e h i g h e s t emissions of

carbon d i o x i d e were f o u n d a long t h e n o r t h slope. T h e c a r b o n

d i o x i d e e rn i s s ion r a t e from t h e n o r t h d o p e averaged 9 . 3 7

~/hour/m', w h i c h was a p p r o x i m a t e l y 2 . 6 tirnes t h e l a n d f i l l

average. The methane exnission r a t e f rom t h e n o r t h s lope was

3 -54 ~ / h o u r / m ~ , which w a s o n l y 1 . 4 times t h e l a n d f i l l

average. The w a s t e under the n o r t h s lope was l a n d f i l l e d f r o m

1995 t o 1 9 9 6 . The w a s t e under t h e n o r t h s l o p e was i n the

v e r y e a r l y stages o f l a n d f i l l gas g e n e r a t i o n ( G a r d n e r and

Probe r t , 1 9 9 2 ) . The early stages of gas g e n e r a t i o n are

c h a x a c t e r i z e d by a high r a t i o o f carbon d i o x i d e t o methane

being generated. A s t h e waste ages, it will b e g i n t o show

emission p a t t e r n s s i m i l a r t o what was found on t h e east

s lope . Carbon d i o x i d e generation w i l l b e g i n t o d e c r e a s e a n d

me thane g e n e r a t i o n w i l l increase a s t h e waste a g e s , and as

methanogenic rnicroorganisrns become more prevalent.

The lack of e m i s s i o n s from t h e w e s t s l o p e coulci be d u e t o

s e v e r a l factors. F i r s t l y , the waste under the west s l o p e is

sorne o f the oldest waste and iç l i k e l y l ong p a s t i t s time o f

p e a k gas g e n e r a t i o n . I n addition, b e c a u s e the waste is

o l d e r , it may con ta in a higher percentage o f rubble than

o t h e r areas due t o d i f f e r e n t landfilling practices i n t h e

past. Additionally, because rnost o f t h e r o a d s around t h e

Landfill originate on the west slope, it is highly compacted

rnaking gas emission on that slope very d i f f i c u l t . Any gas

t h a t is generated under the west slope may be forced to

migrate away from there to other locations for emission.

T h e low l e v e l of emissions frorn the top of the landfill is

believed to be primarily due to the d i f f i c u l t y faced by

l a n d f i l l gas migrating through numerous l ayers of cover

material and w a s t e . Also, the large amount of heavy traffic

on t h e surface of the landfill compacts the surface and

restricts gas emissions .

7 . 6 Emission Rates

The emissions from the Regina Fleet Street Landfill,

3,711,525 L/hour, were greater in total t h a n the Saskatoon

emissions, 1,577,069 L/hour. This is d u e to t h e much l a r g e r

amount of waste present in the Regina study area, 7 million

tonnes, versus 2 million tonnes in the Saskatoon study area.

If an emission rate per unit of waste is examined, the

Regina Fleet Street Landfill was actually emitting less gas

per unit of waste than the Saskatoon Landfill: 4 - 6 5

m3/ tonnedyea r as compared to 6.6 m'/t~nnes/~ear. However,

there is a large amount of rubble, which does not generate

landfill gas, in t h e Regina Fleet Street Landfill. If

r u b b l e , assumed at 30% by volume, were excluded from the

Regina waste totals, t h e n the emission per unit of waste at

the Regina Fleet Street Landfill was 6 -65 m3/tonnes/year.

Since only two landfill gas surveys have been completed in

Saskatchewan, it is difficult to determine the validity of

the data collected from either landfill. In order to

determine if the results of these studies are valid, a

comparison must be made with the results from other landfill

gas studies. The majority of landfill studies state landfill

gas generation in terms of a rate per unit of waste per

year, which allows comparisons to be made between landfills

of differing sizes.

Cornparisons were made between the Regina Fleet Street and 1

Saskatoon Landfill emissions, and generation rate estimates

from other studies. A report by the U.S. EPA stated that

landfill gas emissions varied from 1 to 8 m%~nnes/~ear

(Pohland and Harper, 1987) at observed landfills. Another

report stated that gas emissions at studied landfills have

varied from 3 to 40 m3/tonnes/year (Environment Canada,

1 9 9 5 ) . One source stated gas emission variance £rom numerous

literature sources of 0.059 to 400 ~n~/tonnes/~ear (McBean et

al., 1995). F i v e landfills in Canada and the United States

had landfill gas emission in the range of 2.6 to 9

m)/t~nnes/~ear (Gardner and Probert, 1992) . An additional study observed emissions of 0.34 to 68 m3/tonnedyear

(Barlaz et al,, 1990) a t a large number of landfills in the

United S t a t e s .

The emissions in Regina are in the low to middle range based

on literature data. In addition to the pxesence of large

amounts of rubble, fower emission rates from the Regina

Fleet Street Landfill are to be expected when severa l

factors are taken into account. The temperatures and

moisture contents in the landfill waste samples were far

below what is necessary for optimal landfill gas generation.

The Saskatoon Landfill also f a l l s in the lower to middle

range of recorded emissions. It can be assumed that the

landfill conditions in the Saskatoon Landfill are similar to

the conditions in the Regina Fleet Street Landfill.

7 . 7 LandfiII Gas ControI Considerations

There currently exists no legislation in the province of

Saskatchewan specifically addressing landfill gas emissions,

and their control or utilization. British Columbia has

legislation primarily based on the U.S. €PA guidelines for

L a n d f i l l gas e m i s s i o n s . O n t a r i o a n d Quebec also have more

general regulations addressing l a n d f i l l gas e m i s s i o n s .

The U.S. EPA g u i d e l i n e s on landfill gas emissions are based

on two f a c t o r s : landfill size and Non-Methane Organic Carbon

(NMOC) emissions. If both of these f a c t o r s are met, control

measures are r e q u i r e d . Control measure are only required for

landfills exceeding 2.5 million tonnes in final s i z e which

are emitting 50 t o n n e d y e a r or more of NMOCs. The

r e g u l a t i o n s in British Columbia require c o n t r o l measures at

landfills exceeding 100,000 tonnes of c a p a c i t y and emitting

1 5 0 t o n n e s / y e a r of NMOCs.

With a current s i z e of close t o 7 m i l l i o n tonnes and

e s t i m a t e d NMOC e m i s s i o n s from LAEEM s i m u l a t i o n s ranging from

181 to 4 8 0 t o n n e d y e a r , t h e Regina Fleet S t r e e t Landfill

would be required t o control l a n d f i l l gas emissions i f it

were located i n e i t h e r o f those jurisdictions. The U.S. EPA

and t h e B r i t i s h Columbia government l e a v e the method of

c o n t r o l up t o t h e r e s p e c t i v e l a n d f i l l operator but e n c o u r a g e

landfil1 gas u t i l i z a t i o n if possible.

While the Regina Fleet Street L a n d f i l l may have sufficient

size t o g e n e r a t e usable quantities of gas, the less than

o p t i m a l conditions, p a r t i c u l a r l y low m o i s t u r e content, would

lower generation rates. Because of this, f l a r i n g to control

both methane emissions and VOC emissions may be the b e s t

option.

8.0 Summary, Conclusions and Reconimendations

8.1 Summary and Conclusions

Field investigations and modeling studies were completed for

two semi-axid landfills in Saskatchewan. This research

sesulted in information on the level and pattern of

ernissions, and the landfill gas generation potential and

r i s k s at the studied sites.

Interna1 landfill conditions at the Regina Fleet Street

Landfill suggest that landfill gas generation is occurring,

but at a lower rate than optimal. The pH level found in the

waste was very close to the optimum for landfill gas

generation and shouid not hinder landfill gas generation.

The carbonhitrogen ratio was lower than what would be

required for optimal landfill gas generation but not

significantly lower. Microbial activity was indicated

throughout all layers of the landfill, suggesting that even

though l a n d f i l l conditions rnay not be optimal waste

deconposition is still taking place.

The f a c t o r s that would tend to have the greatest impact on

l a n d f i l l gas generation are temperature and moisture

content. The moisture content in the Regina Fleet Street

Landfill was significantly lower, up to 6O%, than what would

be required for optimal landfill gas generation. The

temperature readings were significantly lower, up to lg°C

lower, than what is deemed optimal for landfill gas

generation. In addition to affecting the amount of landfill

gas generated, interna1 temperatures would also affect the

validity of the estimate made for the total yearly landfill

gas emissions, A summer emission rate estimate was used as

the basis for a yearly rate. A c t u a l l a n d f i l l gas production

and emissions would be expected to be lower than the field

study estirnate.

The field investigations provided an indication of the

suitability of various landfill gas field measuring

equipment. The FID study indicated a high degree of

combustible vapour on t h e south and east s l o p e s of the

l a n d f i l l . The detailed flux chamber study l a t e r confirmed

high emissions on the east slope but did not find high

emissions over the south slope. The FID study also f a i l e d to

àetect t h e h i g h emissions later found on the north slope,

The east slope had a higher amount of methane ernitted than

the north slope. Since methane is a combustible vapour, its

presence in higher quantities could e x p l a i n FID emissions

being found on the east slope and not the north slope. The

FID study did prove very u s e f u l in defining areas that

should be more closely studied. Some of the errors that

occurred with the FID study could be minimized if a greater

nurnber of samples were taken, which is reasonable due to the

s p e e d and ease by which a FID study can be conducted. The

shallow gas wells used to collect trace gas sampks proved

to be both easy to use and highly effective f o r this study.

The field work prov ided useful information with respect to

spatial variability in emissions. A t both landfills, the

emissions showed v e r y high spatial variability and higher

omissions alonq the slopes. Higher ernissions on the slopes

could be due to t h e channeling of landfill gas from other

areas to the slopes caused by the higher degree of

compaction and the greater t h i ckness of cover on the top.

The emissions along the slopes could indicate problems with

the i n t e g r i t y of the interim cover at those locations.

Emission levels found at the Regina Fleet Street Landfill

corresponded very well t o the ages of waste in various

locations. In areas over older waste, the south and west

slopes, lower landfill gas emissions were measured. Areas

over medium aged waste, the east slope, showed a higher

ratio of methane t o carbon dioxide, which is to be expected

in l a t e s stages of decomposition. The north slope, that sits

over very young waste, showed high gas emissions with a high

ratio of c a r b o n dioxide t o methane which would also be

expected.

Sorne level of concern was indicated b y t h e VOC

concentrations. The VOC results from the shallow gas wells

were extremely variable between sampling locations a t b o t h

the Regina F l e e t Street Landfill and the Saskatoon L a n d f i l l .

BTEX and v i n y l chloride concentrations were in t h e low t o

medium r a n g e when compared t o l a n d f i l l s in Ontario. The

f r e o n levels were h i g h for one of the gas wells at both

landfills. I t is d i f f i c u l t to make any definitive

c o n c l u s i o n s about trace gas ernissions at either landfill

because of the l i m i t e d number of samples t h a t were t a k e n .

Based on t h e limited VOC data that was collected, high freon

levels w a r r a n t ccntinued scrutiny i n any f u r t h e r studies,

Additionally, vinyl chloxide and benzene emissions, both

known carcinogens, were found in some wells to be i n excess

of OHSA lirnits. A larger number of sarnples need to be taken

at a larger number of locations at each site.

A U.S. EPA Landfill gas mode1 proved to be a u s e f u l tool in

v a l i d a t i n g the field data. The LAEEM mode1 provided

reasonable results considering t h e limited nature of the

available input data. T h e d e f a u l t parameters that most

closely modeled t h e Regina Fleet Street L a n d f i l l w e r e the

CAA defaults for arid conditions, which gave methane

emisçions of 11,170 tonnes/year and carbon dioxide emissions

of 30,065 tonnedyear. These predictions came within 21% of

field estimates for carbon dioxide and within 10% for

methane. This level of error is comparable to other modeled

landfills with comparable input data. Some of the error will

be due to errors in the field data collection and generation

rate estimation procedure, and not solely due to limitations

of the model. The use of a summer emission rate as the basis

for a yearly estimate may explain why the field emissions

are on the high side of the predictions from the LAEEM. The

Environment Canada default values did not model the Regina

Fleet Street Landfill effectively, due to the very low value

of k that was suggested. The use of the LAEEM defaults for

arid conditions appears suitable for simulating this

landf ill.

Based on both the field studies and the modeling results the

Regina Fleet Street Landfill was emitting approximately

10,000 tonnedyear of methane and 32,500 tonnedyear of

carbon dioxide. Based solely on field studies, the Saskatoon

Landfill was emitting approximately 3200 tonnedyear of

methane and 15,000 tonnedyear O£ carbon dioxide. A higher

total emission rate was measured in Regina, 3,711,525

L/hour, as compared to Saskatoon, 1,577,069 L/hour. The

higher ernission rate is pcimarily due to the much g r e a t e r

quantity of waste present in the Regina study area. When an

emission rate per unit of waste is determined, the Regina

Fleet S t r e e t Landfill actually emitted less gas per unit of

waste, 4.65 m'/t~nnes/~ear, than the Saskatoon Landfill, 6.6

m3/tonnes/year. If rubble is not included in the waste from

the Regina Fleet Street Landfill, the emission per unit of

waste at the Regina Fleet Street Landfill changes to 6.65

m3/tonnes/year. The emissions from bath Saskatchewan

landfills fell in the low to medium range of landfill gas

generation estimates from other studies.

The emissions from the Regina Fleet Street Landfill appear

consistent with what would be expected £rom a semi-arid

landfill with interna1 landfill conditions and landfill

generation potential as found at this landfill. The

emissions from the Saskatoon Landfill are also consistent

with expectations assuming conditions are similar to those

at t h e Regina Fleet Street Landfill.

Based on landfill gas emission regulations from both the

U.S. EPA and the government of British Columbia, the Regina

Fleet Street Landfill would be required to control landfill

gas emissions. Because landfill gas generation conditions

are not optimal and therefore landfill gas generation is

hindered, landfill gas utilization may not be feasible and

flaring would be requixed f o r the control of methane and VOC

emissions.

A number of important factors remain to be i n v e s t i g a t e d a t

the Regina Fleet Street Landfill, or any other semi-arid

landfill. Factors remaining to be s t u d i e d are:

1. T e m p o r a l variations in landfill gas e r n i s s i o n s ove r t h e

course of an entire year should be studied through

longer term testing.

2. Additional studies of interna1 landfill conditions and

landfill gas generation are recommended to provide a

b e t t e r i n t e r p r e t a t i o n of emissions a t serni-arid

landfills.

3. Atmospheric conditions, such as barometric pressure and

temperature, should be examined for their impact on

landfill gas g e n e r a t i o n and emissions.

4 . I t i s a d v i s a b l e to conduct more extensive VOC testing at

landfill sites to determine if dangerous levels of VOCs

are being emitted.

5. More intrusive and expensive landfill gas testing may be

warranted in order to validate t h e results from the flux

chamber study and to determine the suitability of

landfill gas collection and utilization,

6 , Site specific va lues of k and L, should be determined so

that they could be used in future landfill gas modeling

a t semi-arid p r a i r i e l a n d f i l l s . T h e s e va lues cou ld be

based on t h e r e s u l t s from t h i s and additional studies.

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Appendix A

Regina F l e e t S t r e e t Landfill FID R e s u l t s .

.I

,

El 4' El 5' El 6' El 7' E l 8' E l 9' B O ' E21 E22 E23

2.8 6 ?O 1.8 0.5 0.4 0.4 0.3 O O

7/8/97 7/8/97 7/8/97 7/8/97 7/8/97 7/8/97 7/8/97 7/8/97

-

7/8/97 7/8/97

PM PM PM PM PM PM PM PM -

PM- PM

0 7 0 8 09"

O1 O* O1 1* 012 013 014 015 016 017 018 019 020 021 022

7.6 40 NA 2

3.1 3.2 62 2.8 3.4 6.4

L

P l O* P l2 Pl3 Pl4 PIS Pl6

7/9/97 7/9/97 7/9/97 7/9/97 719197 7/9/97

6.3 6.8 17 34 28 23

7/9/97 7/9/97 7/9/97 7/9/97 7/9/97 7/9/97 7/9/97 7/9/97 7/9/97 7/9/97

Area not surveyed Area not surveyed Areanotsurveyed

023 024' 025" 026' Pl P2 P3 P4

PM PM PM PM PM PM PM PM PM PM

PM PM PM PM PM PM

9.8 84 14 5.8 5 5

9.4 NA NA NA 52 9.4 13 8.2

I

PM PM PM PM PM PM 1

7/9/97 7/9/97 7\9/97 7/9/97 7/9/97 7/9/97

1

7/9/97 7/9/97 '

7/9/97 7/9/97 7/9/97 7/9/97 7/9/97 7/9/97

PM PM PM PM PM PM PM PM

P23 P24* P25* P26' QI

Q23 Q24' Q25' (226' RI R2 R3 R4 R5 R6 R7 R8 R9

R I O R I i RI2

I

R13

7/9/97 7/9/97 7/9/97 7/9/97 7/9/97

71 NA NA NA 27

19 NA NA NA 44 50 8 2.5 2.8 2 4 2.8 2.4 2.6 2.4 3.8 32 2- 1 1

PM PM PM PM PM

Area not surveyed Area not surveyed Area not surveyed

7/9/97 7/9/97 7/9/97 7/9/97

711 5/97 711 5197 711 5/97 711 5/97 711 5/97 7/15/97 7/15/97 711 5/97 7/15/97 711 5/97 711 5197 711 5/97 7/15/97

PM PM PM PM

AMIPM AMJPM AMIPM AM/PM AMIPM AMIPM AMIPM AM/PM AWPM AMIPM AMIPM AMIPM AMIPM

Area not surveyed Area not sunreyed Area not surveyed

L

R20 O 7/15/97 AMIPM R21' NA 711 5197 AM/PM R22' NA 711 5/97 AM/PM R23' NA 711 5/97 AMtPM R24' NA 7/15/97 AMIPM R25' NA 711 5/97 AMIPM R26* NA 711 5197 AMIPM SI 26 7/15/97 AWPM S2 980 71 1 5197 AM/PM S3 7.6 711 5/97 AMIPM

AM/PM AMIPM AMIPM AM/PM AMIPM

S4 7.6 711 5/97 AMIPM S5 7.5 7/15/97 AWPM S6 7.2 7/35/97 AMIPM S7 7.4 711 5/97 AM/ PM S8 8.3 7/15/97 AWPM

711 5/97 71 1 5/97 711 5197 711 5197 711 5/97

R I 4 R15 RI6 R I 7 RI8

Area not surveved

1.3 0.8 2.1 0.6 0.8

Area not surveved Area not suweyed Area not surveyed Area not surveved Area not suweved

C

S9 S I O S I 1 S I 2 S I 3 S14

. S?6 S i 7 S I 8 SI9 S20'

T l 14 711 5197 AMIPM 4

T2 16 711 5197 AM/PM T3 9 7/15/97 AMPM T4 8.8 7115197 AMIPM

9.1 8.8 15 30 9

8.8

S21* S22* S23'

7/15/97 711 5197 7/15/97 7/15/97 711 5/97 711 5/97

8.3 8.5 8.6 8.4 NA NA NA NA

r

AMIPM AMIPM AMIPM AMJPM W P M

711 5/97 711 5/97 711 5/97 7/15/97 7/15/97

524' S25'

E

AMfPM AMIPM AWPM AWPM AM/PM AM/PM

Area not surveved Area not suweyed Area not surveyed Area not sunreyed

711 5/97 711 5/97 711 5/97

T5 T6 T7 T8

Z

,

AWPM AMfPM AMlPM

8.9 8.4 8.9 1 -6

1

711 5/97 7/15/97

T9 T l O T l 1

*

711 5/97 7/15/97 7/35/97

Area not surveyed Area not surveved

AMIPM AMIPM

3 3-6 34

AMIPM AMPM AMIPM

AMIPM AMIPM

NA NA

711 5/97 711 5/97

711 5/97 711 5/97

AMIPM AMIPM

1 T l 2 1 3.4 1 7/15/97 1 AMlPM 1 1 T l 3 2.8 711 5/97 AMIPM Tl4 10.5 711 5/97 AMIPM T l 5 2.2 711 5/97 AMIPM I

T l 6 2 711 5/97 AMIPM T l 7 1.9 7/15/97 AWPM T l 8 1.4 711 5/97 AMlPM T l 9 1.2 7/15/97 AWPM T20t T21 T22' T23* T24" T25* T26' U1 U2 U3 U4

NA NA NA NA

U5 14 U6 9 U7 2.7 U8 1.9

NA NA NA 66 9.6 9

- 11

U9 U10

711 5/97 7/15/97 7/15/97 711 5/97

71 1 5/97 717 5/97 711 5/97 711 5/97

U12 U13 U14 U15

711 5/97 711 5/97 711 5/97 7/l5/97 711 5/97 711 5/97 711 5/97

AMIPM AM/PM AM/PM AM/PM

2 3

U16 U17 U18' U19' UZO*

AMlPM AMIPM AMIPM AMIPM

U?? 1 NA NA NA NA NA

B

Area not surveyed Area not suweyed Area not sunreyed Area not suweved

AMlPM AMlPM AMIPM AMIPM AMIPM AMIPM AMIPM

711 51 97 7/15/97 .

3.4 2.8 NA NA NA

V3 V4 V5

Area not surveyed Area not surveyed Area not sunreyed

AM/PM AMIPM

711 5197 711 5/97 711 5/97 711 5/97 711 5197

U21' NA

7/15/97 711 5197 711 5/97 7/15/97 7/15/97

U22' U23* U24' U25' U26' V1

8.6 8.9 8.5

AMIPM AM/PM AMIPM M P M AWPM

Active Area Active Area Active Area Active Area Active Area

AMlPM 1

NA NA NA NA NA i 1

7/15/97 711 5/97 711 5/97

AMJPM AMIPM AMIPM AMIPM

V2 8.2 AWPM AWPM AM/PM

Area not surveyed Area not suweyed Area not suweyed

711 5/97 711 5/97 711 5/97 711 5197 711 5/97 7/15/97 7/15/97 AiWPM

AWPM AM/PM AM/PM W P M AWPM AWPM

Area not suweyed Area not sunreyed Area not surveyed Area not suweyed Area not surveyed

I

V16' V17 VI 8' V I 9' V20'

AM/PM AMIPM AMIPM AM/PM AWPM AM/PM AMlPM

V24* V25" V26' W1

711 5/97 711 5/97 7/15/97 7/15/97 711 5/97 711 5/97 711 5/97

V9 V i O* V? l * V12* V13' V I 4* V15'

V Z * NA 711 5/97 AM/PM Area not sunreyed V23* NA 7/15/97 AM/PM Area not surveved

3.1 2.8 NA NA NA

I m

2.6 3.4 4 3.2 2.6 1.9 2

NA NA NA 8.4

L

W W8 W9

W7 O* W1 l *

711 5/97 7/15/97 7/1 5/97 711 5/97 7/15/97

AWPM

711 5/97 711 5/97 711 5/97 711 5/97

7/15/97 W3

I

AM/PM AWPM AM/PM AM/PM AM/PM

I 7.1

W12* W13* W14' W15*

J

Area not surveyed Area not surveved

W? 6* W17' W18'

X2 5.2 7/15/97 AMIPM X3 5 7/15/97 AMPM , X4 5.1 7/95/97 W M

Area not suweyed Area not suweyed Area not surveyed

AMIPM AMPM AM/PM AM/PM

AMlPM AMIPM AM/PM AMIPM AMIPM

II 40 7.8 10 44 7.4 7.2 8.3 7.3

711 5/97 7/15/97 711 5/97 7/15/97

W19' MO* W21"

B

Area not surveyed , Area not sunreyed Area not surveyed

AMIPM AM/PM M P M

7/15/97 7/75/97 711 5/97 711 5/97 711 5/97

AMIPM AM/PM AMIPM AMIPM

7.4 NA NA NA NA NA

W24' W25' W26*

711 5/97 711 5/97 7/15/97

W4 W5 W6

W22' W23*

Area not surveyed Area not surveyed Area not surveyed

711 5/97 7/15/97 711 5/97

6.2 6.4 150

711 5/97 711 5/97 711 5/97

- AMIPM AM/PM AMIPM

AMJPM AM/PM AMIPM

Area not surveyed Area not suweyed Area not surveved

NA NA NA

Area not surveyed Area not surveved

AM/PM AMIPM

NA NA

7/15/97 7/15/97 7/15/97

7/1 5/97 7/15/97

AM/PM AWPM AMIPM

X6 4.7 - X7 4.6 X8 4,2 X9 4.3

>(?O 4.5 *

X I 1 4.2 -

711 5197 7/15/97 711 5/97 711 5197 7/15/97 711 5/97

- Area not surveyed Area not surveyed Area not surveyed Area not surveyed Area not surveyed

AMIPM W P M AMlPM AM/PM AM1PM AM/PM AMlPM AMIPM AWPM AMIPM AWPM AM/PM AMIPM AMIPM AMIPM AMIPM

X12 4.2 7/15/97 X I 3 4 711 5/97 X I 4 X I 5 X I 6 X i 7' XI 8' X19* - =O* X21* X22' X23' X24' X25' X26'

3.9 3.7 3.4 -

NA NA NA

NA CI-

NA 7

h

Y1 Y2

7/15/97 711 5/97 7/15/97 711 5/97 711 5/97 7/15/97 711 5/97 711 5/97

13-

NA NA NA NA NA

AMIPM AMIPM AMIPM

711 5/97 711 5/97 711 5/97 711 5/97 711 5/97

Area not surveyed Area not surveyed Area not surveyed

O -

O

AWPM 711 5/97 711 5/97

Area not surveyed

Y3 O CI

Y26' NA 7/15/97 M P M Area not surveyed _I

Taken with the use of a Flame Ionaation Detector Notes: Sampling accurred at 30 meter intewals unless otherwise stated

7/15/97 7/15/97 7/15/97 711 5/97 711 5/97 711 5/97 7/15/97 7115197 7/15/97 7/15/97 7/15/97 711 5/97 7/15/97 711 5/97 7/15/97 7/ 15/97 7/15/97 711 5/97 711 5/97 711 5197 7/1 5/97 711 5/97

Y4 Y5 Y6 Y7 Y8 Y9

YI0 Y1 1 Y12 Y13 Y14 Y15 Y16 Y17* Y18* Y19' Y20' Y21' Y 22' Y23* Y 24"

AMIPM AM/ PM

O O. 1 0.2 0.8 0.3 0.4 0.2 0.3 O

0.9 O O

0.2 NA NA NA NA NA NA NA NA

I

AM/PM AMIPM AMIPM AMIPM AM/PM AMlPM AM/PM AMIPM AWPM M M AMIPM

r - C r i *

AMIPM AMIPM AM/PM AMIPM AM/PM AM/PM AMIPM AMPM AMIPM AMIPM AWPM

1

-

s

Areanotsurveyed -

Area not surveyed Area not surveyed Area not surveyed Area not surveyeâ Area not surveyed

I

Area not sutveyed Area not sunreyed

= indicates that the grid stake at that point could not be found so the location was estimated

NIA = That a sample could not be taken due to location of sampling point (Le. location was on a steep slope or else in an area that was being actively worked)

Appendix B

Regina F l e e t Street L a n d f i l l VOC Results.

Propane 25422 25433 O

Freon22 4445 4595 9

1 -Butene/2-Methylpmpene

1 ,%Butadiene Butane

t-2-Butene 2,2-Dimethylpmpane

Bromomethane f

1-Butyne

c-2-Butene

Chloroethane

2-Methylbutane

Freon 1 1

1 -Pentene

2-Methyt-1-Butene

Pentane

24703

4579

1 026

O

104

11411

616

Freonl2

Propyne

Chloromethane

lsobutane (2-Methyipropane) Freonll4

lsoprene (2-Methyl-t .3-Bu tadiene) Ethy lbromide

t-2-Pentene

1.1 -Dichloroethene

e2-Pentene

DichIoromethane 2-Methyl-2-Butene

Freonll3

2.2-Dimethylbutane

Cyciopentene t-4.2-DichIomethene

4-Methyi-1 -Pentene

3-Methyl-1 -Pentene

1 ,l-Dichloroethane

6103

O

14827

810

O

O

O

679

129

14831

O

O

O

10995

23924 4536 ---- 922

O

33 10252

599

Vinvlchloride (ChIometthenel

915

O

11 1

10380

574

O

O

O

O

O

201

1272

24

467

3

1

10

68

10

3 3-

948

6076

O

13538

526

O

O O

527 121

1 3470

O

O

O

1 0873

-1 963

807

O

59

l m 6

579

O

O

292

6

259

188

1 342

1 O

457

- 12

47

3 -1

O

9

35

22

6

9

1014

6 I -

-6

59 2

37

286

O

106

38

-5 1 942

6723

O

15256

683

O

O

O

61 3

1 62

15528

O

O

O

-22

-5

-1 0

4

45

300

O

116

37

1 1 121 77

O

O

220

O

1 74

454

6131

O 1 3654

408

O

O

O 404

149 13733

6

O

O

9

11

40

34

8

12

1 0940

O

O

304

O

273

6 I

4

I

22i

01

47

279

O

158

n

1 O

-38

-57

45

240

O

1 23

nl

2

n 5

1349

17

475

393

1310

7

449

13

I

Cyclopentane -

2.3-Dirnethylbutane L

t4Mettryl-2-Pentene

2-Methylpentane c4Met hyl-ZPentene

SMethylpentane 1 -HexeneM-Methyl-1 -?entene

c-l,2-Dichloroethene

Hexane Chloroform I

t-2-Hexene 2-Ethyl-1-Sutene t-3Methyî-2-Pentene

c-2-Hexene ~Wethyl-2-Pentene

2.2-Dimthylpentane - 1,2-Oichloroethane

Methylcyclapentane

2.4-Dimethylpentane -

1,1,1 -~richloroethane- -

2.23-Trimethyfbutane

1 -Methylcyclopentene -

Benxene I - Carbontetrachloride

Cyclo hexane 24ethylherane

2.3-Dimethylpentane

Cyclohexene

3-Methylhwane Oibromornethane

1.2-Dichloropropane Brornodichlommethane

Trich loroethene

1 -Heptene 2,2,&Trimethylpentane

t-3-Heptene c-3-Heptene

Heptane

t-2-Heptene c-2-Heptene

1147

1121

O

5765

175

3921 O

249 5566

O

139 112

O

O

O

O

O

3943

700 O

O

1 38

4637

O

2402

541 5

2456

7 1

7224

O

O

O

1 32

O

1959

O

O

10447

O

O

2.2-Dimethylhexane 625 703 Methylcyclo hexane 9928 8627

2.5Dimethylhexane 1775 1715 1 - _ 2.4Dirnethylhexane 2242 2223 -_ c/t-1.3-Dichlompmpene O O

1.1.2-Trichloraethane O O

Brornotnchlommethane O O

2,3,4-Trimethylpentane 1266 1214

-1 3

13

3 1

4

1142

1 on O

6058 195

3576

O

250 5329

O

1 84

145

O

4

-5

-1 2 9

-1 4

-32

-29

O

9058

1731 21 56

O

O

O

1280

1 O

11

12

-3 6

I

-3 S

-14

3

12

- -

3 9

-2

2

3 2 9 8

5

-11

11

12

1261

1185

O

6546

205 3934

O

270 5909

O

159

1 54

O

O

O

O

O

4490

739 .

36

O

150

4749

O

2904 5173

2574 84

71 93

O

O

O

1 53 O

21 29 O

O

1 0969 O

O

1136

1051 O

W68

21 1 3710

O

279

5596 O

1 82 1 50

O

O

O

O

O

3961

718 - - - - -

33 O

152

4673 O

2813

5082

2339

78

6842 O

O

O

1 70

O

1903

O

O

9705 O

O

O

133 O

205

O

3904

71 1

14

O

148 4582

O

2666

4987

2384

76

6859

O

O

O

1 57 O

1958

O

O

10038

O

O

8668

1664

21 77

O O

O

117 9

1

1

-1

-7

1

-1 1

8

3

-7

5

-1 9

O

4 m

4

4

-1

8

O

Toluene

2Methyl heptane

4Methylheptane 1

1 -MethylcycJohexene

Dibrornochloromethane

SMethylheptane

c-1.3-Dirnethylcyciohexane

t-1,4-Dimethylcyclohexane

EDB (1,2-Dibromoethane)

2,2,5-Trirnethylhexane

1 -Octene

Octane

t-1,2-Dimethylcyclohexane t-2-Ode ne

Tetrachloroethene

cl ,4/t-1,3-Dimethylcyclohexane

c-2-Octene

c-1.2-Dimethylcydohexane Chlorobenzene

Ethylbenxene

mipxylene

Bromoform

l&Dichlorobutane

Styrene

1.1.2,2-Tetrachloroethane

3.6-Dirnethyloctane

n-Propylbenzene

3-Ethyltoluene

4Ethyltoluene

1 -3.5-Trimethylbenzene

ZEthyltoluene

1 -0eœne

tert-Butylbenzene

1.24-Trimethylbenzene

Decane

Benzyl chloride

13-Dichlombentene

1 .CDichlorobenzene

iso-Butylbenzene

sec-Butylbenzene

1 2.3-Trïmethyibenzene

f l ~ e n e 1.2-Dichlorobanzene

lndane

~1.3-Diethylbenzene

2354 9295

11154

403

O

1 0585

4973

2401

O

O

O

7884

4205

1711

162

1466

O

1040

1088

54731

41 259

O

O

O

O

O

3140

7329

O

5450

4325

O

O

2091 4

31 047

O

O

548

SO

1197

7064

1 9539

O

967

1214

2300

8404

3325

420

O

10561

4507

O

2401

4864

1384

41 54

3238

O

O

14083

20765

O

3

478

448

923

4763

1 1 927

O

793

2584

9555

3701

381

O

11170

4865

2 1 O

70 -4

O

9

2747

O

O

O

7512

4050

1 847 1 73

1428

O

1014

1179

4691 3

37466

O

O

O

O

2539

8090

2783

435

O

9894

4555

1 O

2

15

25 , -1 4

11

6

2774

O

O

O

7295

3938

1847

204

1 394

1428

993

1 058 46990

39480

O

O

O

O

863

O

2436

4794

1334

4065

321 3

O

O

14353

21 562

O

O

494

475

937

4758

1 1 202

O

799

24

34

24

25

33

33

13

21

23

33

39

18

832 1 3 1

-31

12

4

-2

3

2

11

12

3

-14

5 4

-8

-7

3

3 -8

14

9

16

20

16

22

22

26

24

9

29

20

26

27

I

17

2910

601 1

1586

521 8 41 38

O

O

19281

28229

O

O

544

667

1170

6393

15301

O

956

O

21 22 O

O

8327

41 10

O

201

1430

O

1 O1 7

1189

53206

40889

O

O

O

O

Naphthalene 332 248 25 392 253 36 Dodecane 2467 1 657 33 231 5 1 784 23 Hexachlarbutadiene O O O O

Appendix C

Environment Canada k & Lo Values fot the LAEEM.

Environment Canada Default Values for k (Environment Canada, 1997a)

Province - - - - - -

British Columbia O. 028

Alberta 0.006

Manitoba 1 0.006

Saskatchewan 0.006

Quebec 1 0.024

O n t a r i o

N e w Brunswick

- --

0.024

P r i n c e Edwatci Island 1 0 -011

Nova Scotia 1 O.Oi1

Newf oundland

Northwest Territories

0.011

O. 003

Yukon 0.003

Environment Canada Defaul t values fox Lo (Environment Canada, 1997a)

Year Lo (m' of CH4/tonne of w a s t e )

Appendix D

Saskatoon Landfil1 Gas EMssions.

Sampling and Emissions Data for the Spadina MSW Landfill

Saskatoon, Saskatchewan

Sample Location Sampling Tem Emiss ions (~hrlm'). CO2 1 CH4

SEPTEMBER 3(

Sampling and Emissions Data for the Spadina MSW Landfill

Saskatoon. Saskatchewan

L

Sampling and Ernissions Data for the Spadina MSW Landfill

Saskatoon. Saskatchewan L r

Sample Location Sarnpling Temperature (OC) Concentration' (ppm) Emiuions (uhrlm2)' # North East Time ground sample Co2 CH4 Co2 CH4

t m

68 380 425 11:fSAM 17.5 20.0 150 32 2.7 0.6

69 405 460 11:ISAM 18.5 17.0 66 26 1.2 0.5

Sampling and Ernissions Data for the Spadina MSW Landfill

Saskatoon. Saskatchewan

4

Ssmple Location Sampling Temperature CC) , Emlssions (uhrirn2~ # North East l ime ground sample - Co2 CH4 coz CH4

--

102 335 254 9:SO AM 15.0 19.0 280 153 5.1 2.8

Sampling and Emissions Data for the Spadina MSW Landfill

Saskatoon, Saskatchewan

-

Sampling and Emissions Data -

for the Spadina MSW Landfill 1 Saskatoon, Saskatchewan 1

L

Sampling and Emissions Data for the Spadina MSW LandfiIl

Saskatoon. Saskatchewan

1 OCTOBER 5

' Note: Concentrations compensated for zero and span values

* Note: Emissions conected to 25oC

Appendix E.

R e g i n a F l e e t Street Landfil1 Detailed Gas Results.