Manoj Singh Ph.D., P.Eng. Stantec Consulting Ltd.
Designing Dumps/Landfills – How Critical and Crucial it is?
Air & Waste Management Association Canadian Prairie & Northern Section
Edmonton Luncheon Session November 7, 2014
Few Major Documented Landfill Failures
• Bandung landfill, Indonesia (2005) • Garfield Heights,Ohio (2004) • Athens,Greece (2003) • Payatas Landfill, Philippines (2000) - 200 casualties • Bulbul drive landfill, South Africa (1997) • Dona Juana, Columbia (1997) • Taopu,Shanghai,China (1997) • Rumpke sanitary landfill, Cincinnatti, Ohio (1996), • Istanbul, Turkey (1993) – 27 casualties • Maine ,USA (1989)
Cincinatti, Ohio, USA (1996)
Payatas Landfill, Philippines (2000)
(Source - Kolsch and Ziehmann, 2004)
Bandung Landfill, Indonesia ( Feb’2005)
Istanbul, Turkey (1993)
(Source-Kocasoy and Curi 1995)
Contd ……Istanbul, Turkey (1993)
Progressive Failures
Hiriya Landfill Slope Failure, Israel (1997)
(Source – USEPA Bioreactor workshop 2003)
Failed Embankment
Contd …Hiriya Landfill Slope Failure,
(Source – USEPA Bioreactor workshop 2003)
Progressive Failure
Brock West Landfill – Toe Failure (1999)
Source: Dixon Hydrogeology Ltd.
Distorted gas lateral – possibly a result of lateral movement in the waste mass???
Historically landfills failures have typically involved failure of one or more of the following components:
• waste mass, or • liner system, or • final cover system, or • Subgrade or • A combination of any of the above
Components Involved in Landfill Failures
(a) Excess pore pressures/ undesirable leachate head above the liner.
(b) Interface shear strength in composite liner systems -wetting between the Geomembrane and CCL
(c) Toe drain construction - failure
(d) Strength incompatibility with subgrade Foundation and bearing capacity (i.e. cut and fill slopes, cell base)
Factors known to trigger slope instabilities
• Vertical expansion • Piggyback expansion - Particularly, the liner systems of the vertical
piggyback expansions must not suffer damage due to settlement of the underlying existing waste material or due to side slope instability.
• Leachate recirculation - enhancing waste degradation / leachate
treatment • Major Construction activity near the toe of the landfill • Liner tie-up with existing landfill
• Failure of final /interim cover slope due to ongoing construction
activities at the landfill not considered in the design.
Typical situations where structural integrity may become crucial:
Waste Mechanics Waste mechanics is best understood using the fundamental principles of Soil mechanics and it continues to evolve as more research data becomes available Challenge –
• Geotechnical properties of waste e.g. unit weight and shear strength changes over time due to waste decomposition.
• Uncertainties in waste compositions and therefore its bulk properties
MSW Shear strength - function of waste type, composition, compaction, daily cover, moisture conditions, age, decomposition, overburden pressure, etc.
Reference: Singh, M. K., Sharma, J. S. and Fleming, I. (2009). A design chart for estimation of horizontal displacement in municipal landfills. Waste Management, 29(5), 1577-1587.
Three Random variables: • Proportion of the individual
constituent group • Position of individual
constituent group within the MSW matrix
• Properties (Elastic &
Strength parameters) of the individual constituent group
Stochastic Numerical Modeling
Frame height 6’-0”
Airjack (rated pressure 250 psi) Cable extension
transducer
Load cell (45 kN)
Gas outlet port Pore pressure transducer
Strain gauges
Biogas collection system
Leachate injection ports
Peristaltic pump for leachate recirculation
Compression cell (ID 17-1/4”, Ht. 2’-0”
Reference: Singh, M. K. and Fleming, I. R. (2011). Application of hyperbolic model to Municipal Solid Waste. Geotechnique, 61, No. 7, 533-547.
MSW Hyperbolic Model
Reference : Singh, M.K., Sharma, J.S. and Fleming, I. R. (2009). A design chart for estimation of horizontal displacement in municipal landfills, Waste Management 29, 1577-1587
Reference : Singh, M.K., Fleming, I. and Dewaele, P.J. (2005). Slope Stability Analysis of Brock West Landfill, 58th Canadian Geotechnical Conference, Canadian Geotechnical Society.
Brockwest Landfill, Ontario – Toe Failure and Distorted Gas laterals
25.0
27.0
29.0
31.0
33.0
35.0
37.01 10 100 1000 10000 100000
Time (minutes)
Axi
al s
train
(%)
Vertical stress = 84 kPa
Slope (Cαe) =0.104
Initial compression (first 24 hours)
Delayed / secondary compression (Day 62- 90 days)
Collapse of voids, developed as a result of long-term degradation
''a''b
25.0
27.0
29.0
31.0
33.0
35.0
37.01 10 100 1000 10000 100000
Time (minutes)
Axi
al s
train
(%)
Vertical stress = 84 kPa
Slope (Cαe) =0.104
Initial compression (first 24 hours)
Delayed / secondary compression (Day 62- 90 days)
Collapse of voids, developed as a result of long-term degradation
''a''b
9.0
12.0
15.0
18.0
21.0
24.0
27.01 10 100 1000 10000 100000
Time(minutes)
Axia
l stra
in (%
)
Vertical stress = 42 kPa
Slope (Cαe) =0.15
Initial compression (first 24 hours)
Delayed / secondary compression (Day 32- 60 days)
Collapse of voids, developed as a result of long-term degradation
''a ''b
9.0
12.0
15.0
18.0
21.0
24.0
27.01 10 100 1000 10000 100000
Time(minutes)
Axia
l stra
in (%
)
Vertical stress = 42 kPa
Slope (Cαe) =0.15
Initial compression (first 24 hours)
Delayed / secondary compression (Day 32- 60 days)
Collapse of voids, developed as a result of long-term degradation
''a ''b
35.0
37.0
39.0
41.0
43.0
45.01 10 100 1000 10000 100000
Time (minutes)
Axia
l stra
in (%
)
Vertical stress = 180 kPa
Slope (Cαe) =0.131
Initial compression (first 24 hours)
Delayed / secondary compression (Day 92-150 days)
Collapse of voids developed as a result of degradation
35.0
37.0
39.0
41.0
43.0
45.01 10 100 1000 10000 100000
Time (minutes)
Axia
l stra
in (%
)
Vertical stress = 180 kPa
Slope (Cαe) =0.131
Initial compression (first 24 hours)
Delayed / secondary compression (Day 92-150 days)
Collapse of voids developed as a result of degradation
8.5
8.7
8.9
9.1
9.3
9.51 10 100 1000 10000 100000
Time(minutes)
Axi
al s
train
(%)
Initial compression (first 24 hours)
Delayed / secondary compression (Day 2-30 days)
Vertical stress = 22 kPa
Slope (Cαe) =0.0005
8.5
8.7
8.9
9.1
9.3
9.51 10 100 1000 10000 100000
Time(minutes)
Axi
al s
train
(%)
Initial compression (first 24 hours)
Delayed / secondary compression (Day 2-30 days)
Vertical stress = 22 kPa
Slope (Cαe) =0.0005
Mechanism of secondary compression in MSW
Reference - Singh, M.K. and Fleming, I. R. – unpublished article
Singh, M. K., Sharma, J. S. and Fleming, I. R. (2009). Shear strength testing of intact and recompacted samples of municipal solid waste, Canadian Geotechnical Journal, 46(10), 1133-1145.
Summary
• Understanding of waste mechanical behaviour is crucial to designing above ground medium to large landfills.
• Design must consider stability both within and between elements
of the lining system, within the waste mass , interaction with the sub-grade, mobilization of strengths (of special note is geosynthetic elements and interface friction angles )
• Engineering of Landfill is not much different from engineering of the any other infrastructure.
• Having an appropriate Liner design is as important as having a sound design for the infrastructure foundation since there is little you can do once it gets buried.
• Site specific parameters must be evaluated specially when designing vertical / piggyback expansions and leachate injection into the waste.
• Landfill operation must align with the approved design
Thank You Very Much !