2993
Technical Committee 215 /
Comité technique 215
Thermal cycles were found to severely suppress the moisture
uptake of the GCL to as low as 15% of the moisture content
observed under isothermal conditions. Seasonal cooling was
shown to not guarantee sustainable hydration of the GCL
provided that the GCL is subsequently exposed to daily thermal
cycles. The authors suggest that the construction of a leachate
collection system could provide the sufficient normal stress (2-5
kPa) for an adequately high rate of hydration as well as degree
of hydration.
Monteiro et al
., present the results of ramp and direct shear
tests conducted on different geomembrane products (PVC and
smooth and textured HDPE) in contact with a sandy soil
prepared at various degrees of saturation. The results presented
show that the interface friction angle between soil and
geomembranes was insensitive to the variation of the soil
degree of saturation. A progressive interface failure mechanism
was observed in the tests with PVC geomembrane due to the
more extensible nature of this type of geomembrane. The largest
values of interface friction angles were obtained as expected
with the textured HDPE geomembrane, whereas similar lower
values were obtained with the smooth PVC and HDPE
geomembranes.
3 MUNICIPAL SOLID WASTE AND OTHER TYPES OF
WASTE GEOTECHNICAL PROPERTIES
Chen et al.
propose a Bio-Hydro-Mechanical (BHM)
coupled model to investigate solid-liquid-gas interaction
behaviour in landfills containing municipal soils waste (MSW)
with high organic content. The model also takes into account
the release of moisture caused by the MSW biodegradation
process. The development of the model is based on laboratory
and in-situ investigations conducted on MSW to assess their
hydraulic conductivity, gas permeability, and compressive and
shear strength characteristics. The model was applied to
hypothetical waste samples 5 m thick with properties similar to
MSW from Qizishan landfill, China and Orchard Hills landfill,
USA, to predict leachate production, gas pressure and
settlement. Key problems relevant to waste management are
also discussed in particular slope stability issues which can be
caused by the presence of high organic content and
consequently high water content and entrapment of gas
pressures. Figure 4 shows that a mixture of leachate and landfill
gas being ejected to a height of up to 5 m when drilling vertical
extraction wells in Xiaping landfill, China. It indicates that the
presence of very high pore and gas pressures may exist in the
waste body if not managed properly and can be detrimental to
the slope stability of a landfill.
Figure 4 . Ejection of leachate/gas (Chen et al., 2013)
Singh
reports on the shear strength properties of municipal
solid waste (MSW) and indicates that a factor which has not
been paid much attention to is the highly compressible nature of
MSW. It is suggested that due to the large compressibility of
MSW at high normal stresses, a single Mohr Coulomb shear
envelope for a landfill may not be applicable. A new approach
based upon the use of ‘Strength versus Depth’ plot has been
proposed. It is argued that the use of strength versus depth plot
is more appropriate for characterizing shear strength of MSW,
especially for high landfills.
Cañizal et al.
discuss the importance of determining the
mechanical properties of MSW and their implication on landfill
design. The paper highlights the difficulties in measuring these
properties due to the nature of the material tested. The lack of
samples representativeness for laboratory work and difficulties
in interpreting field tests based on the experience gathered with
conventional geotechnical materials have been cited as being
major hurdles in obtaining reliable assessment of MSW
mechanical properties. Back-analysis of failures was suggested
as another possible approach to gather further information.
However uncertainties still exist with this approach since failure
cases are not frequent; and in the few cases which have
occurred, it was difficult to detect the failure surface. A
compilation of strength parameters obtained from laboratory
and in situ tests and from failures (Figure 5) was presented.
Figure 5. MSW strength parameters (
Cañizal
et al., 2013)
Lavoie and Sinclair
discuss the properties of a waste sludge
which comprises primarily clay and iron-sands/grit originating
from iron sands mining and in relation to its disposal in cells .
This wet sludge waste is landfilled in cells to heights up to 25m.
This paper shows that the characteristics of the sludge in situ are
governed both by the nature of the material and the operation
procedures. Key to the process is the limited height of each lift,
together with the period of desiccation between lifts. To
investigate the properties of the sludge for design input,
boreholes and CPT’s were put down through completed landfill
cells of different ages. Field tests (boreholes and CPT’s) on
completed landfill cells of different ages showed that the in situ
sludge experiences significant strength increase with time and
depth, with pore pressures well below hydrostatic conditions.
The sludge was assessed to be non-liquefiable based CPT data
and Atterberg Limits gathered for this project.
0
20
40
60
80
100
0
10
20
30
40
50
60
Back analyses (by 2009)
Strain levels (Stark et al., 2009)
Stark et al. (2009)
Possible new proposal
5%
10%
20%
Friction angle,
(
o
)
Cohesion, c (kPa)
4 SOIL AND GROUNDWATER REMEDIATION
Fronczyk and Garbulewski
present a study on the influence
of MSW landfill leachate on the hydraulic conductivity of
zeolite-sand mixtures (with 50% and 20% content of zeolite).
Results of the study indicate that the hydraulic conductivity of
the reactive material has changed almost by two orders of
magnitude (from 9.25x10
-5
to 1.25 x10
-5
m/s). This change is
believed to have been caused by the reduction of the effective
porosity due to pore clogging. Analysis of calcium carbonate
content showed no significant increase of carbonates in the
samples, while scanning electron microscope study showed
increased calcium content and formation of crystals of calcium
Thermal cycles were found to severely suppress the moisture
uptake of the GCL to as low as 15% of the moisture content
observed under isothermal conditions. Seasonal cooling was
s own to not guarantee sustainabl hydration of the GCL
provided that the GCL is subsequently exposed t daily thermal
cycles. The authors suggest that the construction of a leachate
collection system could provide the sufficient normal str ss (2-5
kPa) for an adequately high rate of hydration as well as degree
of hydration.
Monteiro et al
., present the results of ramp and direct shear
tests conducted on different geomembrane products (PVC and
smooth and textured HDPE) in contact with a sandy soil
prepared at various d grees of sat rati n. The results presented
show that the interfac friction angl between soil a
ge membranes was insensitive to the variation of the soil
degree of saturation. A progressive interface failure mecha ism
was observed in th tests with PVC geomembrane due to the
m re extensible nature of this type of g omembra e. The largest
valu s of interface friction angles were obtained as expected
ith the textured HDPE geomembrane, whereas similar lower
values were obtain d with the smooth PVC and HDPE
geomembran s.
3 MUNICIPAL SOLID WASTE AND OTHER TYPES OF
WASTE GEOTECHNICAL PROPERTIES
Chen et al.
propose a Bio-Hydro-Mechanical (BHM)
coupled model to investigate solid-liquid-gas interaction
behaviour in landfills containing municipal soils waste (MSW)
with high organic c ntent. The model also takes into account
the r lease of moisture caused by the MSW biodegradation
process. The development of the model is based on laboratory
and in-situ investigations conducte on MSW to assess their
ydraulic conductivity, gas p rmeability, and compressive and
shear strength charact ristics. The model was applied to
hypothetical waste samples 5 m thick with properties similar to
MSW from Qizishan landfill, China and Orchard Hills landfill,
USA, to predict leachate production, gas pressure and
settlement. Key problems relevant to waste management are
also discussed in particular slope stability issues which can be
caused by the pr sence of high organic content a
consequently high water content and entrapment of gas
pressures. Figure 4 shows that a mixture of leachate and landfill
gas being ejected to a height f up to 5 m when drilling vertical
extraction wells in Xi ping la dfill, China. It indicates that the
presence of very high pore nd gas pr ssur s may exist in the
waste body if not managed properly and can be detrimental to
the slope stability of a landfill.
Figure 4 . Ejection of leachate/gas (Chen et al., 2013)
Singh
reports on the shear strength properties of municipal
solid waste (MSW) and indicates that a factor which has not
been paid much attention to is the highly compressible nature of
MSW. It is suggested that due to the large compressibility of
MSW at high normal stresses, a single Mohr Coulomb shear
envelope for a l ndfill may not be applicable. A new approach
based upon the use of ‘Strength versus Depth’ plot has been
proposed. It is argued that the use of strength versus depth plot
is more appropriate for characterizing shear strength of MSW,
especially for high landfills.
Cañizal et al.
discuss the importance of determining the
mechanical properties of MSW and their implication on landfill
design. The paper highlights the difficulties in measuring these
properties due to the nature of the material test d. The lack of
samples representativeness for laboratory work and difficulties
in interpreting field tests based on the experience gathered with
conventional geotech ical materials have been cited as being
major hurdles in obtaining reliable assessment of MSW
mechanical properties. Back-analysis of failures w s suggested
as another possible approach to gather further information.
However uncertainties still exist with this approach since failure
cases are not frequent; and in the few cases which have
occurred, it was difficult to detect the failure surface. A
c mpilatio of strength parameters obtained from laboratory
and in situ tests and from failures (Figur 5) was presented.
Figure 5. MSW strength parameters (
Cañizal
et al., 2013)
Lavoie and Sinclair
discuss the properties of a waste sludge
which comprises primarily clay and iron-sands/grit originating
from iron sands mining and in relation to its disposal in cells .
This wet sludge waste is landfilled in cells to heights up to 25m.
This paper shows that the characteristics of the sludge in situ are
governed both by the nature of the material and the operation
procedures. K y to the process is the limited height of each lift,
together with the period of desiccation between lifts. To
investigate the properties of the sludge for design input,
boreholes and CPT’s were put down through completed landfill
cells of different ages. Field tests (boreholes and CPT’s) on
completed landfill cells of different ages showed that the i situ
sludge xperiences significant stre gth increase with time and
depth, with pore pressures well below hydrostatic conditions.
The sludge was ass ssed to b non-liquefiabl based CPT data
an Atterb rg Limit athered for this project.
0
20
40
60
80
100
0
10
20
30
40
50
60
Back analys s (by 2009)
Strain levels (Stark et al., 2009)
Stark et al. (2009)
Possible new proposal
5%
10%
20%
Friction angle,
(
o
)
Cohesion, c (kPa)
4 SOIL AND GROUNDWATER REMEDIATION
Fronczyk and Garbulewski
present a study on the influence
of MSW landfill leachate on the hydraulic conductivity of
zeolite-sand mixtures (with 50% and 20% content of zeolite).
Results of the study indicate that the hydraulic conductivity of
the reactive material s changed almost by two orders f
magnitude (from 9.25x10
-5
to 1.25 x1
-5
m/s). This change is
believed to have been caus d by t reduction of the effective
porosity due to pore clogging. Analysis of calcium carbonate
content showed no significant increase of carbonates in the
samples, while scanning electron microscope study showed
increased calcium content a d formation f crystals of calcium
Thermal cycle were found to severely suppress the moisture
uptake of the GCL to as low as 15% of the moisture content
observed under isothermal conditions. Seasonal cooling was
sh wn to ot guarantee sustainable hydration of the GCL
provided that the GCL is subsequently exposed to daily thermal
cycles. The authors suggest that the construction of a leachate
collection system could provide the sufficient normal stress (2-5
kPa) for an adequately high rate of hydration as well as degree
of hydration.
Monteiro et al
., present the r sults of ramp and direct shear
tests c nducted on different geomembrane products (PVC and
smooth and textured HDPE) in contact with a sandy soil
pr pared at various degrees of saturation. The results presented
sh w that the interface friction angle betwee soil and
geomembranes was insensitive to the variation of the soil
deg ee of saturation. A progressive interface failure mechanism
was observed in the tests with PVC geomembrane due to the
more extensible nature of this type of geomembrane. The largest
values of interface friction angles were obtained as expected
with the textured HDPE geomembrane, whereas similar lower
values were obtained with the smooth PVC and HDPE
ge membranes.
3 MUNICIPAL SOLID WASTE AND OTHER TYPES OF
WASTE GEOTECHNICAL PROPERTIES
Chen et al.
propose a Bio-Hydro-Mechanical (BHM)
coupled model to investigate solid-liquid-gas interaction
behaviour in landfills containing municipal soils waste (MSW)
with high organic content. The model also takes into account
the release of moisture caused by the MSW biodegradation
process. The development of the model is based on laboratory
and in-situ investigations conducted on MSW to assess their
hydraulic conductivity, gas permeability, and compressive and
shear strength characteristics. The model was applied to
hypothetical waste samples 5 m thick with properties similar to
MSW from Qizishan landfill, China and Orchard Hills landfill,
USA, to predict leachate production, gas pressure and
settlement. Key problems relevant to waste management are
also discussed i particular slope stability issues which can be
caused by the presence of high organic content and
consequently high water content and entrapment of gas
pressures. Figure 4 shows that a mixture of leachate and landfill
gas being ejected to a height of up to 5 m when drilling vertical
extraction wells in Xiaping landfill, China. It indicates that the
presence of very high pore and gas pressures may exist in the
waste body if not managed properly and can be detrimental to
the slope stability of a landfill.
based upon the use of ‘Strengt ve sus D pth’ plot has been
proposed. It is argued that the use of str ngth versus depth plot
is more appropriate for characterizing shear strength of MSW,
especially for high landfills.
Cañizal et al.
discuss the importance of determining the
mechanical properties of MSW and their implication on landfill
design. The paper highlights the difficulties in measuring these
properties due to the nature of the material tested. The lack of
samples representativeness for laboratory work and difficulties
in interpreting field tests based on the experience gathered with
conventional geotechnical materials have been cited as being
major hurdles in obtaining reliable assessment of MSW
mechanical properties. Back-analysis of failures was suggested
as another possible approach to gather further information.
However uncertainties still exist with this approach since failure
cases are not frequent; and in the few cases which have
occurred, it was difficult to detect the failure surface. A
compilation of strength parameters obtained from laboratory
and in situ tests and from failures (Figure 5) was presented.
Figure 5. MSW strength parameters (
Cañizal
et al., 2013)
Lavoie and Sinclair
discuss the properties of a waste sludge
which comprises primarily clay and iron-sands/grit originating
from iron sands mining and in relation to its disposal in cells .
This wet sludge waste is landfilled in cells to heights up to 25m
This paper s ows that the characteristics of the sludge in situ are
governed both by the n ture of the material and the perati n
proced res. Key to the process is the limited height of e ch lift,
togeth r with the period of desiccation between li ts. To
inve tigate the roperties of the sludge for design input,
borehole and CPT’s were put down through ompleted landfill
cells of differ nt ges. Field tests (boreholes and CPT’s) on
completed landfill ells of different ges showed that the in situ
sludge experiences significant strength increase with time and
depth, with pore pressures well below hydrostatic conditions.
The sludge was assessed to be non-liquefiable based CPT data
0
20
40
60
80
100
0
10
20
30
40
50
60
Back analyses (by 2009)
Strain levels (Stark et al., 2009)
Stark et al. (2009)
Possible new proposal
5%
10%
20%
Friction angle,
(
o
)
Cohesion, c (kPa)
Thermal cycles were found to severely suppress the moisture
uptake of the GCL to as low as 15% of the moisture content
observed under isothermal conditions. Seasonal cooling was
shown to not guarantee sustainable hydration of the GCL
provided that the GCL is subsequently exposed to daily thermal
cycles. The authors suggest that the construction of a leachate
collection system could provide the sufficient normal stress (2-5
kPa) for an adequately high rate of hydration as well as degree
of hydration.
Monteiro et al
., present the results of ramp and direct shear
tests conducted on different geomembrane products (PVC and
smooth and textured HDPE) in contact with a sandy soil
prepared at various degrees of saturation. The results present
show that the interface friction angle between soil and
geomembranes was insensitive to the variation of the soil
degree of saturation. A progressive interface failure mechanism
was observed in the tests with PVC geomembrane due to the
more extensible nature of this type of geomembrane. The largest
values of interface friction angles were obtained as expected
with the textured HDPE geomembrane, whereas si ilar lower
values were obtained with the s ooth PVC and HDPE
geomembranes.
3 MUNICIPAL SOLID WASTE AND OTHER TYPES OF
WASTE GEOTECHNICAL PROPERTIES
Chen et al.
propose a Bio-Hydro-Mechanical (BHM)
coupled model to investigate solid-liquid-gas interaction
behaviour in landfills containing municipal soils waste (MSW)
with high organic content. The model also takes into account
the release of moisture caused by the MSW biodegradation
process. The development of the model is based on laboratory
and in-situ investigations conducted on MSW to assess their
hydraulic conductivity, gas permeability, and compressive and
shear strength characteristics. The model was applied to
hypothetical waste samples 5 m thick with properties similar to
MSW from Qizishan landfill, China and Orchard Hills landfill,
USA, to predict leachate production, gas pressure and
settlement. Key problems relevant to waste management are
also discussed in particular slope stability issues which can be
caused by the presence of high organic content and
consequently high water content and entrapment of gas
pressures. Figure 4 shows that a mixture of leachate and landfill
gas ei g ejected to a height of up to 5 m when drilling vertical
extractio wells in Xiaping landfill, China. It indicates that the
presence of very high pore and gas pressures may exist in the
wast body if not managed properly and can be d tr m nt l to
the slope stability of a landfill.
based upon the use of ‘Strength versus Depth’ plot has been
proposed. It is argued that the use of strength versus depth plot
is more appropriate for characterizing shear strength of MSW,
especially for high landfills.
Cañizal et al.
discuss the importance of determining the
mechanical properties of MSW and their implication on landfill
design. The paper highlights the difficulties in measuring these
properties due to the nature of the material tested. The lack of
samples representativeness for laboratory work and difficulties
in interpreting field tests based on the experience gathered with
conventional geotechnical materials have been cited as being
major hurdles in obtaining reliable assessment of MSW
mechanical properties. Back-analysis of failures was suggested
as another possible approach to gather further information.
However uncertainties still exist with this approach since failure
cases are not frequent; and in the few cases which have
occurred, it was difficult to detect the failure surface. A
compilation of strength parameters obtained from laboratory
and in situ tests and from failures (Figure 5) was presented.
Figure 5. MSW strength parameters (
Cañizal
et al., 2013)
Lavoie and Sinclair
discuss the properties of a waste sludge
which comprises primarily clay and iron-sands/grit originating
from iron sands mining and in relation to its disposal in cells .
This wet sludge waste is landfilled in cells to heights up to 25m.
This paper shows that the characteristics of the sludge in situ are
governed both by the nature of the material and the operation
procedures. Key to the process is the limited height of each lift,
together with the period of desiccation between lifts. To
investigate the properties of the sludge for design input,
boreholes and CPT’s were put down through completed landfill
cells of different ages. Field tests (boreholes and CPT’s) on
completed landfill cells of different ages showed that the in situ
sludge experiences significant strength increase with time and
depth, with pore pressures well below hydrostatic conditions.
The sludge was assessed to be non-liquefiable based CPT data
0
20
40
60
80
100
0
10
20
30
40
50
60
Back analyses (by 2009)
Str in l vels (Stark et al., 2009)
Stark et al. (2009)
Possible new proposal
5%
10%
20%
Friction angle,
(
o
)
Cohesion, c (kPa)
