Settlement Analysis | Foundation Engineering - Civil Engineering (CE) PDF Download

 Page 1


Evaluating waste and foundation
settlement whenever a separatory
liner will be used between old and
new waste is important for
determining tensile strain on
components.  For purposes of this
policy, all references to a separatory
liner will include any newly
constructed separatory liner system
or any previously placed cap system
that will be converted to a separatory
liner system.
SETTLEMENT ANALYSES
This chapter provides information to use when analyzing the potential for failure due to settlement at an
Ohio waste containment facility.  It is important to account for settlement in the design of a waste
containment facility because:
! overall settlement can result in changes to liquid drainage flow paths for leachate, surface water, or
waste water, and can cause damage to pipes, destruction of geonets, and reduction or reversal of
grades; and
! differential settlement can result in damage or failure of liner systems, piping, containment berms,
and other engineered components.
Overall settlement and differential settlement should be analyzed
for all of the following soil materials including, but not limited to:
in situ soils, mine spoil, added geologic material, structural fill,
recompacted soil liners, and waste materials.  Differential
settlement analyses should focus on areas where changes in
foundation materials warrant evaluation, such as areas with high
walls, separatory liner over waste, changes in soil stratigraphy
laterally or vertically, and where significant abrupt changes in
loading occur.
The vertical and lateral variability of settlement characteristics
across a site, and the changes in the increase in vertical stress
created by the geometry of the waste containment facility will
cause each location of a facility to settle different amounts.  The facility must be designed to account for
the stresses and strains that result from settlement occurring in the foundation and waste mass. 
REPORTING
This section describes the information that should be
submitted to demonstrate that a facility is not susceptible to
damage from settlement.  Ohio EPA recommends that the
following information be included in its own section of a
geotechnical and stability analyses report.  At a minimum,
Any drawings or cross sections referred to
in this policy that are already present in
another part of the geotechnical and stability
analyses report can be referenced rather than
duplicated in each section.  It is helpful if
the responsible party ensures the referenced
items are easy to locate and marked to show
the appropriate information.
Page 2


Evaluating waste and foundation
settlement whenever a separatory
liner will be used between old and
new waste is important for
determining tensile strain on
components.  For purposes of this
policy, all references to a separatory
liner will include any newly
constructed separatory liner system
or any previously placed cap system
that will be converted to a separatory
liner system.
SETTLEMENT ANALYSES
This chapter provides information to use when analyzing the potential for failure due to settlement at an
Ohio waste containment facility.  It is important to account for settlement in the design of a waste
containment facility because:
! overall settlement can result in changes to liquid drainage flow paths for leachate, surface water, or
waste water, and can cause damage to pipes, destruction of geonets, and reduction or reversal of
grades; and
! differential settlement can result in damage or failure of liner systems, piping, containment berms,
and other engineered components.
Overall settlement and differential settlement should be analyzed
for all of the following soil materials including, but not limited to:
in situ soils, mine spoil, added geologic material, structural fill,
recompacted soil liners, and waste materials.  Differential
settlement analyses should focus on areas where changes in
foundation materials warrant evaluation, such as areas with high
walls, separatory liner over waste, changes in soil stratigraphy
laterally or vertically, and where significant abrupt changes in
loading occur.
The vertical and lateral variability of settlement characteristics
across a site, and the changes in the increase in vertical stress
created by the geometry of the waste containment facility will
cause each location of a facility to settle different amounts.  The facility must be designed to account for
the stresses and strains that result from settlement occurring in the foundation and waste mass. 
REPORTING
This section describes the information that should be
submitted to demonstrate that a facility is not susceptible to
damage from settlement.  Ohio EPA recommends that the
following information be included in its own section of a
geotechnical and stability analyses report.  At a minimum,
Any drawings or cross sections referred to
in this policy that are already present in
another part of the geotechnical and stability
analyses report can be referenced rather than
duplicated in each section.  It is helpful if
the responsible party ensures the referenced
items are easy to locate and marked to show
the appropriate information.
the following information about an overall settlement and differential settlement analysis should be
reported to Ohio EPA:
! A narrative and tabular summary of the results of the settlement analyses,
! A summary and a detailed discussion of the results of the subsurface investigation that apply to the
settlement analyses and how they are used in the analyses,
! A summary of the approach, methodologies, and equations used to model settlement of the facility,
! If any of the settlement parameters were interpolated by using random generation or another
method, then information must be provided to explain in detail, the equations and methodology, and
how the settlement parameters were generated,
! Plan view maps showing the top of the liner system, the liquid containment and collection system,
the location of the points where settlement is calculated, the expected settlement associated with
each point, and the limits of the waste containment unit(s).
Drawings showing the critical cross sections analyzed.  The cross sections should include the:
! Soil stratigraphy,
! Temporal high phreatic surfaces,
! The range of the tested settlement parameters of each layer,
! Depth of excavation,
! Location of engineered components of the facility that may be adversely affected by
settlement,
! The amount of settlement calculated at each point chosen along the cross section,
! The detailed settlement calculations of the engineering components,
! Any figures, drawings, or references relied upon during the analysis marked to show how they relate
to the facility, and
! The detailed tensile strain analysis.
! If vertical sump risers are included in the facility design,
then include:
! A narrative and tabular summary of the results of
the bearing capacity analysis,
Ohio EPA discourages the use of vertical
sump risers in solid waste containment
units and hazardous waste containment
units.  This is due to the inherent
difficulties they present during filling
operations, and the potential they create for
damaging liner systems.
Page 3


Evaluating waste and foundation
settlement whenever a separatory
liner will be used between old and
new waste is important for
determining tensile strain on
components.  For purposes of this
policy, all references to a separatory
liner will include any newly
constructed separatory liner system
or any previously placed cap system
that will be converted to a separatory
liner system.
SETTLEMENT ANALYSES
This chapter provides information to use when analyzing the potential for failure due to settlement at an
Ohio waste containment facility.  It is important to account for settlement in the design of a waste
containment facility because:
! overall settlement can result in changes to liquid drainage flow paths for leachate, surface water, or
waste water, and can cause damage to pipes, destruction of geonets, and reduction or reversal of
grades; and
! differential settlement can result in damage or failure of liner systems, piping, containment berms,
and other engineered components.
Overall settlement and differential settlement should be analyzed
for all of the following soil materials including, but not limited to:
in situ soils, mine spoil, added geologic material, structural fill,
recompacted soil liners, and waste materials.  Differential
settlement analyses should focus on areas where changes in
foundation materials warrant evaluation, such as areas with high
walls, separatory liner over waste, changes in soil stratigraphy
laterally or vertically, and where significant abrupt changes in
loading occur.
The vertical and lateral variability of settlement characteristics
across a site, and the changes in the increase in vertical stress
created by the geometry of the waste containment facility will
cause each location of a facility to settle different amounts.  The facility must be designed to account for
the stresses and strains that result from settlement occurring in the foundation and waste mass. 
REPORTING
This section describes the information that should be
submitted to demonstrate that a facility is not susceptible to
damage from settlement.  Ohio EPA recommends that the
following information be included in its own section of a
geotechnical and stability analyses report.  At a minimum,
Any drawings or cross sections referred to
in this policy that are already present in
another part of the geotechnical and stability
analyses report can be referenced rather than
duplicated in each section.  It is helpful if
the responsible party ensures the referenced
items are easy to locate and marked to show
the appropriate information.
the following information about an overall settlement and differential settlement analysis should be
reported to Ohio EPA:
! A narrative and tabular summary of the results of the settlement analyses,
! A summary and a detailed discussion of the results of the subsurface investigation that apply to the
settlement analyses and how they are used in the analyses,
! A summary of the approach, methodologies, and equations used to model settlement of the facility,
! If any of the settlement parameters were interpolated by using random generation or another
method, then information must be provided to explain in detail, the equations and methodology, and
how the settlement parameters were generated,
! Plan view maps showing the top of the liner system, the liquid containment and collection system,
the location of the points where settlement is calculated, the expected settlement associated with
each point, and the limits of the waste containment unit(s).
Drawings showing the critical cross sections analyzed.  The cross sections should include the:
! Soil stratigraphy,
! Temporal high phreatic surfaces,
! The range of the tested settlement parameters of each layer,
! Depth of excavation,
! Location of engineered components of the facility that may be adversely affected by
settlement,
! The amount of settlement calculated at each point chosen along the cross section,
! The detailed settlement calculations of the engineering components,
! Any figures, drawings, or references relied upon during the analysis marked to show how they relate
to the facility, and
! The detailed tensile strain analysis.
! If vertical sump risers are included in the facility design,
then include:
! A narrative and tabular summary of the results of
the bearing capacity analysis,
Ohio EPA discourages the use of vertical
sump risers in solid waste containment
units and hazardous waste containment
units.  This is due to the inherent
difficulties they present during filling
operations, and the potential they create for
damaging liner systems.
! A summary and a detailed discussion of the results of the subsurface investigation that apply
to the bearing capacity and how they were used in the analyses,
! A summary of the approach, methodologies, and equations used to model the bearing
capacity of the facility.
DESIGN CRITERIA
Ohio EPA does not specify or recommend a factor of safety to use during settlement analysis.  Instead,
facilities must be designed so they satisfy applicable minimum regulatory design requirements at the
time they are ready to receive waste and continue to satisfy applicable minimum design requirements
after settlement is complete (at least 100% of primary settlement plus the secondary settlement expected
using a time-frame of 100 years or another time-frame acceptable to Ohio EPA).  This also applies to
any increases in weight of the facility (e.g., vertical or horizontal expansions, increases in containment
berm height).  Therefore, it is important for responsible parties and designers to consider the possibility
for increasing the weight of the facility and account for the additional settlement during the initial
design.  Failure to do so is likely to result in a facility being prevented from vertically expanding because
to do so would cause the waste containment system or the liquid removal systems to become
compromised.  Applicable minimum regulatory design requirements, include, but are not limited to:
! Maintaining the minimum slopes of liners and pipes, 
! Maintaining the integrity of soil berms, liners, barrier layers, and other engineered components,
! Maintaining the integrity of geosynthetics,
! Ensuring that all piping will be in working order, and
! Showing that liquids in the liquid control and collection systems will be below maximum levels
allowed and otherwise meet performance standards.
Ohio EPA requires that the tensile strength of geosynthetics
are ignored when evaluating the slope stability of a facility
design.  This is because plastic materials creep under stress,
and over time, the thickness of the geosynthetics will
decrease under constant stress.  Geosynthetics may crack
under constant stress, and for geonets, constant stress may
cause the collapse of the drainage pathways rendering the
material useless.  Tensile strain may occur in geosynthetics
when placing the materials with too little slack, dragging
subsequent layers of geosynthetic across previously placed layers during installation, placing materials
such as soil, drainage material, waste, or waste water on top of the geosynthetics, and during settlement.
When tensile strain is unavoidable, the facility should be designed to minimize tensile strain in
geotextiles, geomembranes, geosynthetic clay liners, geocomposite drainage layers, leachate collection
piping, and waste water piping.  Generally, it is recommended that strain not exceed the manufacturer’s
One notable exception to the requirement for
designing geosynthetic systems without
accounting for tensile strength of the
materials is when a slip layer of geosynthetic
above an FML is purposefully included in a
design (see Chapter 9 for more information).
Page 4


Evaluating waste and foundation
settlement whenever a separatory
liner will be used between old and
new waste is important for
determining tensile strain on
components.  For purposes of this
policy, all references to a separatory
liner will include any newly
constructed separatory liner system
or any previously placed cap system
that will be converted to a separatory
liner system.
SETTLEMENT ANALYSES
This chapter provides information to use when analyzing the potential for failure due to settlement at an
Ohio waste containment facility.  It is important to account for settlement in the design of a waste
containment facility because:
! overall settlement can result in changes to liquid drainage flow paths for leachate, surface water, or
waste water, and can cause damage to pipes, destruction of geonets, and reduction or reversal of
grades; and
! differential settlement can result in damage or failure of liner systems, piping, containment berms,
and other engineered components.
Overall settlement and differential settlement should be analyzed
for all of the following soil materials including, but not limited to:
in situ soils, mine spoil, added geologic material, structural fill,
recompacted soil liners, and waste materials.  Differential
settlement analyses should focus on areas where changes in
foundation materials warrant evaluation, such as areas with high
walls, separatory liner over waste, changes in soil stratigraphy
laterally or vertically, and where significant abrupt changes in
loading occur.
The vertical and lateral variability of settlement characteristics
across a site, and the changes in the increase in vertical stress
created by the geometry of the waste containment facility will
cause each location of a facility to settle different amounts.  The facility must be designed to account for
the stresses and strains that result from settlement occurring in the foundation and waste mass. 
REPORTING
This section describes the information that should be
submitted to demonstrate that a facility is not susceptible to
damage from settlement.  Ohio EPA recommends that the
following information be included in its own section of a
geotechnical and stability analyses report.  At a minimum,
Any drawings or cross sections referred to
in this policy that are already present in
another part of the geotechnical and stability
analyses report can be referenced rather than
duplicated in each section.  It is helpful if
the responsible party ensures the referenced
items are easy to locate and marked to show
the appropriate information.
the following information about an overall settlement and differential settlement analysis should be
reported to Ohio EPA:
! A narrative and tabular summary of the results of the settlement analyses,
! A summary and a detailed discussion of the results of the subsurface investigation that apply to the
settlement analyses and how they are used in the analyses,
! A summary of the approach, methodologies, and equations used to model settlement of the facility,
! If any of the settlement parameters were interpolated by using random generation or another
method, then information must be provided to explain in detail, the equations and methodology, and
how the settlement parameters were generated,
! Plan view maps showing the top of the liner system, the liquid containment and collection system,
the location of the points where settlement is calculated, the expected settlement associated with
each point, and the limits of the waste containment unit(s).
Drawings showing the critical cross sections analyzed.  The cross sections should include the:
! Soil stratigraphy,
! Temporal high phreatic surfaces,
! The range of the tested settlement parameters of each layer,
! Depth of excavation,
! Location of engineered components of the facility that may be adversely affected by
settlement,
! The amount of settlement calculated at each point chosen along the cross section,
! The detailed settlement calculations of the engineering components,
! Any figures, drawings, or references relied upon during the analysis marked to show how they relate
to the facility, and
! The detailed tensile strain analysis.
! If vertical sump risers are included in the facility design,
then include:
! A narrative and tabular summary of the results of
the bearing capacity analysis,
Ohio EPA discourages the use of vertical
sump risers in solid waste containment
units and hazardous waste containment
units.  This is due to the inherent
difficulties they present during filling
operations, and the potential they create for
damaging liner systems.
! A summary and a detailed discussion of the results of the subsurface investigation that apply
to the bearing capacity and how they were used in the analyses,
! A summary of the approach, methodologies, and equations used to model the bearing
capacity of the facility.
DESIGN CRITERIA
Ohio EPA does not specify or recommend a factor of safety to use during settlement analysis.  Instead,
facilities must be designed so they satisfy applicable minimum regulatory design requirements at the
time they are ready to receive waste and continue to satisfy applicable minimum design requirements
after settlement is complete (at least 100% of primary settlement plus the secondary settlement expected
using a time-frame of 100 years or another time-frame acceptable to Ohio EPA).  This also applies to
any increases in weight of the facility (e.g., vertical or horizontal expansions, increases in containment
berm height).  Therefore, it is important for responsible parties and designers to consider the possibility
for increasing the weight of the facility and account for the additional settlement during the initial
design.  Failure to do so is likely to result in a facility being prevented from vertically expanding because
to do so would cause the waste containment system or the liquid removal systems to become
compromised.  Applicable minimum regulatory design requirements, include, but are not limited to:
! Maintaining the minimum slopes of liners and pipes, 
! Maintaining the integrity of soil berms, liners, barrier layers, and other engineered components,
! Maintaining the integrity of geosynthetics,
! Ensuring that all piping will be in working order, and
! Showing that liquids in the liquid control and collection systems will be below maximum levels
allowed and otherwise meet performance standards.
Ohio EPA requires that the tensile strength of geosynthetics
are ignored when evaluating the slope stability of a facility
design.  This is because plastic materials creep under stress,
and over time, the thickness of the geosynthetics will
decrease under constant stress.  Geosynthetics may crack
under constant stress, and for geonets, constant stress may
cause the collapse of the drainage pathways rendering the
material useless.  Tensile strain may occur in geosynthetics
when placing the materials with too little slack, dragging
subsequent layers of geosynthetic across previously placed layers during installation, placing materials
such as soil, drainage material, waste, or waste water on top of the geosynthetics, and during settlement.
When tensile strain is unavoidable, the facility should be designed to minimize tensile strain in
geotextiles, geomembranes, geosynthetic clay liners, geocomposite drainage layers, leachate collection
piping, and waste water piping.  Generally, it is recommended that strain not exceed the manufacturer’s
One notable exception to the requirement for
designing geosynthetic systems without
accounting for tensile strength of the
materials is when a slip layer of geosynthetic
above an FML is purposefully included in a
design (see Chapter 9 for more information).
recommendations for the aforementioned components.  Any design that results in geosynthetics being in
strain must be accompanied with documentation and test results showing that the proposed materials
will maintain the integrity of the systems of which they are a part under the calculated strain.  The testing
will need to represent the stress history that will be caused by the loading conditions experienced by the
materials at the time of installation through final loading with waste or waste water.
The above criteria to be applied during settlement analysis are appropriate if the design assumptions are
conservative; site-specific, higher quality data are used; and the calculation methods chosen are
demonstrated to be valid and appropriate for the facility.  The use of a design that is more robust than
regulatory requirements may be warranted whenever:
! A failure would have a catastrophic effect upon human health or the environment,
! Uncertainty exists regarding the accuracy, consistency, or validity of data, and no opportunity exists
to conduct additional testing to improve or verify the quality of the data.
The responsible party should ensure that the design and specifications in all authorizing documents and
the QA/QC plans clearly require that the assumptions and specifications used in the settlement analyses
for the facility will be followed during construction, operations, and closure.  If the responsible party
does not do this, it is likely that Ohio EPA will require the assumptions and specifications from the
settlement analyses to be used during construction, operations, and closure of a facility through such
means as are appropriate (e.g., regulatory compliance requirements, approval conditions, orders,
administrative consent agreements).
From time to time, changes to the facility design may be needed that will alter the assumptions and
specifications used in the settlement analysis.  If this occurs, a request to change the facility design is
required to be submitted for Ohio EPA approval in
accordance with applicable rules.  The request to change the
facility design must include a new settlement analysis that
uses assumptions and specifications appropriate for the
change request or contain a justification for why a new
analysis is not necessary.
SETTLEMENT ANALYSIS
A settlement analysis includes the overall settlement of a
facility to ensure that pipes will remain intact and any liquid
drainage flow paths for leachate, surface water, or waste
water will satisfy design requirements after settlement is
complete.  Settlement analyses also include any differential
settlement across a facility to ensure that engineered
components will not be damaged, liquid drainage paths will
be maintained, and the facility will satisfy design
requirements, not only at the time of construction,
In most cases, immediate settlement will not
be a concern because the immediate
settlement will occur during construction. 
However, immediate settlement must be
taken into account at some facilities.  This is
especially true for facilities where
construction is staged to build several
phases.  For example, one year, three berms
and a liner system are constructed. Then the
following year a large berm is constructed
along the remaining upslope edge of the
liner.  In this instance, immediate settlement
from the placement of the last berm may
cause a portion of the liner to settle into a
grade that does not meet design criteria. 
This could result in improper leachate flow
or improper drainage of lagoons and ponds. 
Methods for analyzing immediate settlement
can be found in most geotechnical and
foundation textbooks (e.g., McCarthy, 2002;
Holtz and Kovacs, 1981, etc).
Page 5


Evaluating waste and foundation
settlement whenever a separatory
liner will be used between old and
new waste is important for
determining tensile strain on
components.  For purposes of this
policy, all references to a separatory
liner will include any newly
constructed separatory liner system
or any previously placed cap system
that will be converted to a separatory
liner system.
SETTLEMENT ANALYSES
This chapter provides information to use when analyzing the potential for failure due to settlement at an
Ohio waste containment facility.  It is important to account for settlement in the design of a waste
containment facility because:
! overall settlement can result in changes to liquid drainage flow paths for leachate, surface water, or
waste water, and can cause damage to pipes, destruction of geonets, and reduction or reversal of
grades; and
! differential settlement can result in damage or failure of liner systems, piping, containment berms,
and other engineered components.
Overall settlement and differential settlement should be analyzed
for all of the following soil materials including, but not limited to:
in situ soils, mine spoil, added geologic material, structural fill,
recompacted soil liners, and waste materials.  Differential
settlement analyses should focus on areas where changes in
foundation materials warrant evaluation, such as areas with high
walls, separatory liner over waste, changes in soil stratigraphy
laterally or vertically, and where significant abrupt changes in
loading occur.
The vertical and lateral variability of settlement characteristics
across a site, and the changes in the increase in vertical stress
created by the geometry of the waste containment facility will
cause each location of a facility to settle different amounts.  The facility must be designed to account for
the stresses and strains that result from settlement occurring in the foundation and waste mass. 
REPORTING
This section describes the information that should be
submitted to demonstrate that a facility is not susceptible to
damage from settlement.  Ohio EPA recommends that the
following information be included in its own section of a
geotechnical and stability analyses report.  At a minimum,
Any drawings or cross sections referred to
in this policy that are already present in
another part of the geotechnical and stability
analyses report can be referenced rather than
duplicated in each section.  It is helpful if
the responsible party ensures the referenced
items are easy to locate and marked to show
the appropriate information.
the following information about an overall settlement and differential settlement analysis should be
reported to Ohio EPA:
! A narrative and tabular summary of the results of the settlement analyses,
! A summary and a detailed discussion of the results of the subsurface investigation that apply to the
settlement analyses and how they are used in the analyses,
! A summary of the approach, methodologies, and equations used to model settlement of the facility,
! If any of the settlement parameters were interpolated by using random generation or another
method, then information must be provided to explain in detail, the equations and methodology, and
how the settlement parameters were generated,
! Plan view maps showing the top of the liner system, the liquid containment and collection system,
the location of the points where settlement is calculated, the expected settlement associated with
each point, and the limits of the waste containment unit(s).
Drawings showing the critical cross sections analyzed.  The cross sections should include the:
! Soil stratigraphy,
! Temporal high phreatic surfaces,
! The range of the tested settlement parameters of each layer,
! Depth of excavation,
! Location of engineered components of the facility that may be adversely affected by
settlement,
! The amount of settlement calculated at each point chosen along the cross section,
! The detailed settlement calculations of the engineering components,
! Any figures, drawings, or references relied upon during the analysis marked to show how they relate
to the facility, and
! The detailed tensile strain analysis.
! If vertical sump risers are included in the facility design,
then include:
! A narrative and tabular summary of the results of
the bearing capacity analysis,
Ohio EPA discourages the use of vertical
sump risers in solid waste containment
units and hazardous waste containment
units.  This is due to the inherent
difficulties they present during filling
operations, and the potential they create for
damaging liner systems.
! A summary and a detailed discussion of the results of the subsurface investigation that apply
to the bearing capacity and how they were used in the analyses,
! A summary of the approach, methodologies, and equations used to model the bearing
capacity of the facility.
DESIGN CRITERIA
Ohio EPA does not specify or recommend a factor of safety to use during settlement analysis.  Instead,
facilities must be designed so they satisfy applicable minimum regulatory design requirements at the
time they are ready to receive waste and continue to satisfy applicable minimum design requirements
after settlement is complete (at least 100% of primary settlement plus the secondary settlement expected
using a time-frame of 100 years or another time-frame acceptable to Ohio EPA).  This also applies to
any increases in weight of the facility (e.g., vertical or horizontal expansions, increases in containment
berm height).  Therefore, it is important for responsible parties and designers to consider the possibility
for increasing the weight of the facility and account for the additional settlement during the initial
design.  Failure to do so is likely to result in a facility being prevented from vertically expanding because
to do so would cause the waste containment system or the liquid removal systems to become
compromised.  Applicable minimum regulatory design requirements, include, but are not limited to:
! Maintaining the minimum slopes of liners and pipes, 
! Maintaining the integrity of soil berms, liners, barrier layers, and other engineered components,
! Maintaining the integrity of geosynthetics,
! Ensuring that all piping will be in working order, and
! Showing that liquids in the liquid control and collection systems will be below maximum levels
allowed and otherwise meet performance standards.
Ohio EPA requires that the tensile strength of geosynthetics
are ignored when evaluating the slope stability of a facility
design.  This is because plastic materials creep under stress,
and over time, the thickness of the geosynthetics will
decrease under constant stress.  Geosynthetics may crack
under constant stress, and for geonets, constant stress may
cause the collapse of the drainage pathways rendering the
material useless.  Tensile strain may occur in geosynthetics
when placing the materials with too little slack, dragging
subsequent layers of geosynthetic across previously placed layers during installation, placing materials
such as soil, drainage material, waste, or waste water on top of the geosynthetics, and during settlement.
When tensile strain is unavoidable, the facility should be designed to minimize tensile strain in
geotextiles, geomembranes, geosynthetic clay liners, geocomposite drainage layers, leachate collection
piping, and waste water piping.  Generally, it is recommended that strain not exceed the manufacturer’s
One notable exception to the requirement for
designing geosynthetic systems without
accounting for tensile strength of the
materials is when a slip layer of geosynthetic
above an FML is purposefully included in a
design (see Chapter 9 for more information).
recommendations for the aforementioned components.  Any design that results in geosynthetics being in
strain must be accompanied with documentation and test results showing that the proposed materials
will maintain the integrity of the systems of which they are a part under the calculated strain.  The testing
will need to represent the stress history that will be caused by the loading conditions experienced by the
materials at the time of installation through final loading with waste or waste water.
The above criteria to be applied during settlement analysis are appropriate if the design assumptions are
conservative; site-specific, higher quality data are used; and the calculation methods chosen are
demonstrated to be valid and appropriate for the facility.  The use of a design that is more robust than
regulatory requirements may be warranted whenever:
! A failure would have a catastrophic effect upon human health or the environment,
! Uncertainty exists regarding the accuracy, consistency, or validity of data, and no opportunity exists
to conduct additional testing to improve or verify the quality of the data.
The responsible party should ensure that the design and specifications in all authorizing documents and
the QA/QC plans clearly require that the assumptions and specifications used in the settlement analyses
for the facility will be followed during construction, operations, and closure.  If the responsible party
does not do this, it is likely that Ohio EPA will require the assumptions and specifications from the
settlement analyses to be used during construction, operations, and closure of a facility through such
means as are appropriate (e.g., regulatory compliance requirements, approval conditions, orders,
administrative consent agreements).
From time to time, changes to the facility design may be needed that will alter the assumptions and
specifications used in the settlement analysis.  If this occurs, a request to change the facility design is
required to be submitted for Ohio EPA approval in
accordance with applicable rules.  The request to change the
facility design must include a new settlement analysis that
uses assumptions and specifications appropriate for the
change request or contain a justification for why a new
analysis is not necessary.
SETTLEMENT ANALYSIS
A settlement analysis includes the overall settlement of a
facility to ensure that pipes will remain intact and any liquid
drainage flow paths for leachate, surface water, or waste
water will satisfy design requirements after settlement is
complete.  Settlement analyses also include any differential
settlement across a facility to ensure that engineered
components will not be damaged, liquid drainage paths will
be maintained, and the facility will satisfy design
requirements, not only at the time of construction,
In most cases, immediate settlement will not
be a concern because the immediate
settlement will occur during construction. 
However, immediate settlement must be
taken into account at some facilities.  This is
especially true for facilities where
construction is staged to build several
phases.  For example, one year, three berms
and a liner system are constructed. Then the
following year a large berm is constructed
along the remaining upslope edge of the
liner.  In this instance, immediate settlement
from the placement of the last berm may
cause a portion of the liner to settle into a
grade that does not meet design criteria. 
This could result in improper leachate flow
or improper drainage of lagoons and ponds. 
Methods for analyzing immediate settlement
can be found in most geotechnical and
foundation textbooks (e.g., McCarthy, 2002;
Holtz and Kovacs, 1981, etc).
but also after differential settlement is complete.  At least two components of settlement are required to
be evaluated: primary settlement and secondary settlement.  The strain on engineered components
created by differential settlement should also be calculated.  Settlement is considered completed when at
least 100% of primary settlement and the secondary settlement expected using a time-frame of 100 years
or another time-frame acceptable to Ohio EPA is taken into account.
Due to the natural variability in soils and changes in the vertical stress across a facility, settlement
characteristics and the amount of settlement are likely to be different from one point to another both
vertically and laterally across a site.  The variability of settlement characteristics and the changes in
vertical stress due to the geometry of the waste containment unit(s) across a site should be discussed in
detail in the summary of the subsurface investigation submitted with the settlement calculations.  This
discussion should describe each compressible layer found at the site, indicate if these layers exist under
all or just part of the site, and discuss the extent of the variability of these layers throughout their
distribution.
The vertical and lateral variability of settlement characteristics across a site and the significant damage
that settlement can cause to engineered components emphasize the need for thorough and careful
subsurface investigation. To facilitate a settlement analysis, it is recommended that several points be
chosen along the critical cross sections of the facility and that the location of these points be spaced at a
distance that would best characterize the facility depending on its size, geometry, and the variability of
the soil materials at the site.
Responsible parties of waste containment facilities often want to expand existing facilities.  This
requires that a settlement analysis take into account the settlement of such things as natural foundation
materials, structural fill, and waste.  Estimating the settlement of structural fill, waste, and some soil
units that are extremely variable can be difficult.  This is especially true of municipal solid waste (MSW)
because of the diverse mechanics occurring in the waste such as biodegradation, mechanical
compression (bending, crushing, reorientation of waste caused by applied stress), and raveling
(movement of fine materials into waste voids by seepage, vibration, or decomposition) (Sowers 1968,
1973).  Settlement of MSW requires specialized analysis, is not well understood, and is beyond the
scope of this manual.  Some publications (e.g., Ling et al, 1998; Spikula, 1996; Wall and Zeiss, 1995)
discuss the estimation of MSW settlement.  They have been referenced at the end of this chapter.
For greenfield sites, the area within the entire footprint of each proposed waste containment unit must be
adequately sampled (see Chapter 3). The characterization of each compressible layer, both vertically and
laterally, is then used to calculate the expected settlement at points along any flow line or for any portion
of the facility.
When a settlement analysis is being conducted for an existing waste containment facility where borings
cannot be placed within the limits of waste placement, the variability in the soil profile of the
compressible layers under the existing facility can be estimated by using the settlement characteristics
from adjacent borings outside the limits of waste placement or borings performed prior to the existing
waste placement.
For MSW landfills, when a separatory liner system is placed between existing waste and new waste, it
must be placed at a minimum ten percent slope in all areas except along flow lines augmented by