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 !