This document discusses a research study investigating the long-term use of tire-derived aggregate (TDA) in landfill leachate collection and drainage systems (LCDS). Over 294,000 tons of TDA have been used in Alberta's LCDS since 1996. The research aims to test the long-term hydraulic conductivity of TDA compared to gravel through lysimeter experiments. Preliminary findings show that Alberta leachate chemistry varies significantly between landfills. TDA has higher porosity and compressibility than gravel but lower density. Future work will further examine TDA properties and short and long-term permeability of LCDS to provide data supporting continued TDA use.

1. Use of tire-derived aggregate (TDA)
for landfill leachate collection and
drainage systems
Marclus Mwai, Kristine Wichuk & Dr. Daryl
McCartney
University of Alberta
April 2010
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2. Background
 Albertans discard 5 million tires per year.
 Recycling of used tire carried out under
Alberta’s Tire Recycling Program.
 Products available currently produced:
• Pour-in-place rubber surfacing for playgrounds, floor
and roofing tiles, and TDA for drainage purposes.
 Other uses include blending crumb with
asphalt for road construction.
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3. Leachate Collection and Drainage System
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4. Types of TDA produced in Alberta
Four types:
• Medium truck tire shred (MTT).
• Off-the-road tire shred (OTR).
• Passenger and light truck tire shred (PLTT).
• Also mixtures of types, e.g. PLTT and OTR.
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5. Use of TDA in LCDS
 TDA used in LCDS since 1996.
 Useful product in offsetting need for natural
aggregate, e.g. gravel, in LCDS.
 TDA has high permeability, hence the
continued application in LCDS
 Over 294,000 tonnes (t) used to 2008:
• 213,450 t - PLTT
• 62,510 t - MTT
• 18,040 t - OTR 5

6. TDA use in Leachate Collection & Drainage System
(LCDS) of Alberta landfills
Class Type of landfill No. Landfills With TDA
I Hazardous Waste 2 0
Municipal Sanitary
32 22
(>10,000 t/yr)
Municipal Sanitary
II 100 7
(<10,000 t/y)
Industrial Waste 26 2
III Dry Waste 6 1
TOTAL 180 32
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7. Design & Operating Standards for
All Types of LCDS Materials
 Main feature of a drainage layer:
• Ensure efficient drainage and collection of leachate.
 Design standards require less than 300 mm
leachate mounding (Alberta Environment 2010).
 Need high hydraulic conductivity:
• e.g. ≥ 0.01 cm per second.
 Clogging can lower hydraulic conductivity, key
mechanisms are:
• Sedimentation, biofilm formation, adsorption.
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8. Need for Investigation
 Investigation of long-term performance of
LCDS using gravel or TDA:
• No record of LCDS failures in Alberta.
• Few laboratory studies of LCDS anywhere.
• Ontario study (Rowe & McIsaac 2005):
 Suggested the potential for long-term (30 to 50 years)
clogging of both gravel and TDA.
 Based on their work, TDA may clog faster than gravel.
 Leachate quality and quantity, and TDA properties are
different than those used in Alberta.
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9. Need for Investigation
 Limited investigation of long-term performance
of LCDS:
• Testing specific to Alberta situation needed.
• It is necessary to quantify mechanisms and to
identify required design specifications.
• Specifications to cover TDA types available in AB.
• Specifications to ensure high quality performance of
TDA in LCDS.
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10. Today’s Objective
Introduce you to the on-going
research activities.
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11. Research Program & Status
1. Overview of research activities.
2. Some preliminary findings:
a. Alberta leachate characteristics.
b. TDA physical properties.
3. Future activities & expected outcome.
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12. 1. Overview of the research
 Main objective of research: to test long-term
hydraulic conductivity of TDA and gravel.
 Main factors to consider: leachate chemistry;
compressibility and type of TDA.
 Lysimeter apparatus will be used to simulate
LCDS
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13. Complete apparatus
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14. 2a. Alberta Leachate characteristics
• Leachate chemistry very variable between
and within landfills.
• Chemistry depends on age of landfill, waste
composition, seasons.
• Results consistent with information available
in the literature.
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15. 2a. Alberta Leachate Characteristics
Leachate Quality Trends
0 10 20 30
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16. 2b. Tire shred properties
Gravel (as reported
Property TDA
in literature)
Specific gravity (ratio) 1.18-1.38 2.67-2.72
Dry density loose
385-469 1370
(kg/m3)
Initial porosity (%) 62-72 46
Water absorption (%) 2-4 1-3
Compressibility (%) 40-50 Not compressible
Hydraulic conductivity
4.9-59.3 0.78
(cm/sec), uncompacted
Particle size distribution
25-300 50-80
(mm)
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17. 2b. TDA Properties
Compressibility of tire shreds
1.2
1.0 PLTT
OTR
Depth (m)
0.8 MTT
0.6
0.4
0.2
0.0
0 50 100 150 200 250 300 350
Overburden Pressure (kPa)
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18. 3. Future activities
 To complete TDA physical testing.
 To investigate short and long-term
permeability of LCDS.
 To provide data that facilitates the use of
TDA in LCDS.
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19. 3. Expected Outcome
 Research expected to provide information/
data that facilitates the use of TDA in LCDS.
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20. Summary
 There is a need to investigate factors affecting
LCDS
 Leachate chemistry variable over space and
time:
 Within and between landfills.
 Physical properties of TDA to be determined.
 Long-term tests being conducted to compare
hydraulic conductivity of TDA and gravel
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21. Acknowledgements
• Alberta Recycling and Management Authority for
commissioning the research and providing
financial and logistical support.
• Edmonton Waste Management Centre of
Excellence for housing the lysimeter apparatus
and technical support.
• City of Edmonton for technical support and
supplying the leachate for the experiment.
• Alberta Research Council for the design,
fabrication and commissioning of lysimeters.
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22. Thank you
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