3 lnnwood Circle Suite 220 Little Rock AR 72211-middot2449 (ti11) 225~7779 Fax (501) 225-673B

AFIND- ~~5ampJ10 Mr Bryan Leamons PE Pmtgmiddot 0 Vie -5 (- R4 s Engineering Supervisor RECO Solid Waste Management Division If M~Y 0 5ZDfO ~ Arkansas Department of Environmental Quality 530 I Northshore Drive Doc JPif 5~ D North Little Rock AR 72218-5317 ToiLL 7

RE Request to Use Geosynthetic Clay Liner in Composite Liner System

WCA Union County Class I Landfill Solid Waste Permit No 0248-S I-R4 FTN Project No 6533-052

Dear Mr Leamons

On behalf of Waste Corporation of Arkansas (WCA) FTN Associates Ltd (FTN) is submitting this request to use a geosynthetic clay liner (GCL) at their Union County Class I Landfill The proposed use ofllie GCL is to replace the compacted clay portion of the composite liner system that will be constructed over older waste This submittal includes a description of the proposed design the purpose for the use of the GCL liner in place of the compacted clay and engineering calculations demonstrating the slope and settlement stability of the GCL liner

WCA has recently hired an earthwork contractor to begin the construction of Waste Cell 12 at the Union County Landfill The proposed use of the GCL will be part of this construction project and your attention to this request would he greatly appreciated

If you have any questions or comments please feel free to contact me or Jason Ghidotti PE at (50 I) 225-7779

Respectfully Submitted FTN ASSOCIATES LTD ()

~~ ul Crawford PE PG MAY - 4 2010

Senior Project Manager

Enclosures

PWClrml

Cc Nick Marotta Regional Engineer Waste Corporation of America Mike Howell Landfil Manager WCA Union County Landfill

RIWP JILES16533-Ol2ICORRESPONDENCEIL-B LEAMONS Ol-Ol-iOIL-B LEAMONS 05-0l-iODOCX

Regional Offices FayettevIlle AR Baton Rouge LA and Jackson MS bull WVIIWftn-assoccom bull ftnftn~assoc_com

SUMMARY OF PROPOSED USE OF GEOSYNTHETIC CLAY LINER WCA Union County Landfill

Waste Cell 12 Construction Project BACKGROUND WCA owns and operates the Union County Class 1 Landfill (Solid Waste Permit No 0248‐S1‐R4) located near El Dorado AR The facility has been in operation since 1988 and the facility permit has been modified four times The initial four disposal cells (Cells 1 2 3 and 4) were constructed prior to current solid waste regulations and do not include composite liner systems (Figure 1 presents the layout of the facility) When the facility modified its permit in 1997 for a horizontal and vertical expansion the Arkansas Department Environmental Quality (ADEQ) required that the southern slopes between these older waste cells and the proposed expansion area be lined with a composite liner system prior to placement of new waste A review of the permit records indicates that the liner system was to be 18‐inches of compacted clay a 60‐mil HDPE geomembrane and a 2‐foot thick protective cover soil layer When WCA constructed the bottom liner system over Cells 1 2 3 and the eastern portion of Cell 4 in 2003 the contractor had considerable difficulty meeting compaction requirements for the compacted clay liner material in the proposed composite liner system In total the contractor installed approximately 4 feet of clay instead of the required 18‐inches due to the highly compressible waste beneath the slope The placement of the extra soil cost WCA additional expense and valuable clay liner material Only the western portion of Cell 4 (about one acre) remains to be lined WCA intends to construct the liner system during the construction of the newly re‐configured Cell 12 (Figure 1) in May 2010 WCA proposes to use a geosynthetic clay liner (GCL) in place of the 18‐inches of compacted clay for this remaining portion of the slope The reasons for this proposal are

1 As presented in the attached documents the reinforced GCL will provide additional stability against potential settlement of the liner system (see Appendix A)

2 The GCL will allow easier installation of the liner system particularly in the vicinity of the existing landfill gas extraction system components in Cells VB and 4

3 As shown in Appendix B the GCL will not compromise the stability of the slope for either static or dynamic conditions

4 GCLs have been used as an alternative to compacted clay liners for many years and in many cases are more appropriate for the given application

The proposed design for the remaining portion of Cell 4 is shown as Figure 2 The proposed cross‐section is

bull Six inches of a prepared subgrade consisting of compacted clayey soil bull Reinforced GCL

bull 60‐mil textured HDPE geomembrane liner bull Two feet of protective cover soil

ENGINEERING ANALYSES GCLs have numerous benefits for use in engineering applications including landfill liner systems There is substantial research and literature demonstrating the equivalency of GCLs to compacted clay liners (CCLs) Two areas that the ADEQ Solid Waste staff has expressed concern relate to slope stability and settlement stability To address these concerns FTN has performed a stability analysis of the proposed design and assessed potential settlement issues of GCLs Each of these issues is summarized below Settlement Stability There have been numerous studies on settlement stability of GCLs versus CCLs The major concern of settlement of any lining system is the ability to withstand large amounts of tensile strain caused by settlement of the underlying waste mass Two studies performed in the 1990s are included in Appendix A and highlight the ability of GCLs to withstand a much higher amount of strain compared to CCLs As summarized in the two articles the GCLs exhibit better resistance to the tensile strains caused by settlement due to the higher elasticity of the synthetic materials and the additional reinforcement that connects the two layers of geotextiles together In comparison CCLs are more susceptible to cracking and deformation at far less settlement which increases the permeability of the layer and compromises the integrity of the liner system This fact is highlighted in the first article (LaGatta 1997) where GCLs maintained low permeabilities through a range of strains that CCLs failed in tension cracking (01 ndash 4) and beyond up to 10 tensile strain Slope Stability FTN analyzed the stability of the proposed bottom liner system to be installed over the western slope of Cell 4 The analysis included an assessment of the slope for both static and dynamic loading conditions for both circular and veneer failure conditions Based on the results of the analysis the proposed design is stable for both conditions A summary of the analysis is presented in Appendix B

APPENDIX A GCL Settlement Articles

APPENDIX B Slope Stability Analysis

Page 1 of 3 532010

SUMMARY OF SLOPE STABILITY ANALYSIS WCA Union County Class 1 Landfill

Technical Approach The purpose of the stability analysis is to determine if the proposed design of the landfill is stable under both static and dynamic (earthquake) conditions Specifically the stability of a section of existing waste lined with a geosynthetic clay liner (GCL) then filled to a significant height with waste is evaluated Figure B1 presents the location of the most critical slope section of the Class 1 landfill which was used in the stability analysis This section corresponds with an area of maximum GCL-lined waste length and significant waste fill height Based on a review of existing documents for the landfill facility the following cross-section was developed for the analysis bull The existing Class 1 waste is filled to elevations ranging from 215 to 243 NGVD bull 18 inches of intermediate cover soil is in place over the existing Class 1 waste bull A portion of the existing waste (approximately 185 linear feet) in this cross-section will be

lined with the following materials (bottom to top) bull Six (6) inches of compacted soil to act as a foundation layer bull A geosynthetic clay liner (GCL) bull A 60-mil textured HDPE geomembrane bull Two (2) feet of protective cover soil

bull Class 1 waste will be filled to design grades with a layer of interim cover installed as a foundation layer for the construction of the final cap

bull An 18-inch thick compacted clay liner will be installed on top of the interim cover layer bull A 40-mil LDPE geomembrane liner will be installed on top of the compacted clay liner bull A geocomposite drainage layer will be installed over the geomembrane bull 12 inches of protective cover soil will be placed on top of the geocomposite bull A six (6)-inch vegetative soil layer will be installed on top of the protective cover bull The upper slope of the landfill is approximately 5 and the maximum side slope is 25

(41) bull The maximum elevation of the proposed modified final cover for the landfill is

approximately 283 NGVD at this cross-section Figure B2 is a typical cross section of the landfill slope that was used in the analysis Table B1 presents the strength parameters used in the analysis The values were taken from published data for the materials considered in the analysis For the earthquake load a horizontal acceleration of 02 g was used based on published data by the United States Geological Survey for the El Dorado Arkansas area (01 second surface acceleration 2 exceedance in 50 years 2008)

Page 2 of 3 532010

Table B1 Strength Parameters for Slope Stability Analysis

LayerSoil

Saturated Unit

Weight (pcf)

Internal Friction Angle

(degrees)

Cohesion (psf)

Interface Friction Angle

(degrees)

Interface Adhesion

(psf)

Vegetative Cover (1) 140 25 200

Compacted Clay (1) 120 25 500

Existing Intermediate Cover (1) 120 20 500

Geocomposite (2) 59 28 50

Geomembrane Liner (2) 57 25 0

Geosynthetic Clay Liner (3) 50 17 0

Protective Cover Soil (1) 100 30 0

Compacted Soil ldquoFoundationrdquo Layer (1)

100 23 500

Class 1 Waste (4) 70 36 300

Notes (1) Civil Engineering Reference Manual Sixth Edition Lindeburg MR Foundation

Engineering Handbook Second Edition Fang H-Y (2) GSE material data sheets (3) CETCO material data sheets (4) Bray et al (2009) ldquoShear Strength of Municipal Solid Wasterdquo Journal of Geotechnical and

Geoenvironmental Engineering June p 709-722 Summary of Analysis The GEO-SLOPE SlopeW 2007 computer program was used in the stability analysis Slope stability was assessed for both static and dynamic conditions The Ordinary and Modified Bishop Ordinary and Modified Janbu and Morgenstern-Price methods were used in determining stability A circular failure was analyzed for the sitersquos critical slope profile The minimum static and dynamic factors of safety were selected to represent the worst-case failure conditions for circular slope failure Table B2 presents a summary of the factor of safety (FS) against failure for both static and dynamic conditions for the circular failure mode

Page 3 of 3 532010

The minimum recommended FS against slope failure for static loading is 15 The minimum static FS of 48 occurred for a circular failure through the edge of the GCL liner system The minimum recommended FS against slope failure for dynamic loading is 10 The minimum dynamic FS of 23 occurred for a circular failure through the edge of the GCL liner system Based on the assessment the site design is stable with respect to circular failure in both static and dynamic conditions Figures B3 and B4 present the slope stability failure surface outputs

Table B2 Summary of Factor of Safety Values

Cover AlternativeFailure Mode Static Condition FS Dynamic Condition FS

Circular Failure 23 48

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

bull 60‐mil textured HDPE geomembrane liner bull Two feet of protective cover soil

ENGINEERING ANALYSES GCLs have numerous benefits for use in engineering applications including landfill liner systems There is substantial research and literature demonstrating the equivalency of GCLs to compacted clay liners (CCLs) Two areas that the ADEQ Solid Waste staff has expressed concern relate to slope stability and settlement stability To address these concerns FTN has performed a stability analysis of the proposed design and assessed potential settlement issues of GCLs Each of these issues is summarized below Settlement Stability There have been numerous studies on settlement stability of GCLs versus CCLs The major concern of settlement of any lining system is the ability to withstand large amounts of tensile strain caused by settlement of the underlying waste mass Two studies performed in the 1990s are included in Appendix A and highlight the ability of GCLs to withstand a much higher amount of strain compared to CCLs As summarized in the two articles the GCLs exhibit better resistance to the tensile strains caused by settlement due to the higher elasticity of the synthetic materials and the additional reinforcement that connects the two layers of geotextiles together In comparison CCLs are more susceptible to cracking and deformation at far less settlement which increases the permeability of the layer and compromises the integrity of the liner system This fact is highlighted in the first article (LaGatta 1997) where GCLs maintained low permeabilities through a range of strains that CCLs failed in tension cracking (01 ndash 4) and beyond up to 10 tensile strain Slope Stability FTN analyzed the stability of the proposed bottom liner system to be installed over the western slope of Cell 4 The analysis included an assessment of the slope for both static and dynamic loading conditions for both circular and veneer failure conditions Based on the results of the analysis the proposed design is stable for both conditions A summary of the analysis is presented in Appendix B

APPENDIX A GCL Settlement Articles

APPENDIX B Slope Stability Analysis

Page 1 of 3 532010

SUMMARY OF SLOPE STABILITY ANALYSIS WCA Union County Class 1 Landfill

Technical Approach The purpose of the stability analysis is to determine if the proposed design of the landfill is stable under both static and dynamic (earthquake) conditions Specifically the stability of a section of existing waste lined with a geosynthetic clay liner (GCL) then filled to a significant height with waste is evaluated Figure B1 presents the location of the most critical slope section of the Class 1 landfill which was used in the stability analysis This section corresponds with an area of maximum GCL-lined waste length and significant waste fill height Based on a review of existing documents for the landfill facility the following cross-section was developed for the analysis bull The existing Class 1 waste is filled to elevations ranging from 215 to 243 NGVD bull 18 inches of intermediate cover soil is in place over the existing Class 1 waste bull A portion of the existing waste (approximately 185 linear feet) in this cross-section will be

lined with the following materials (bottom to top) bull Six (6) inches of compacted soil to act as a foundation layer bull A geosynthetic clay liner (GCL) bull A 60-mil textured HDPE geomembrane bull Two (2) feet of protective cover soil

bull Class 1 waste will be filled to design grades with a layer of interim cover installed as a foundation layer for the construction of the final cap

bull An 18-inch thick compacted clay liner will be installed on top of the interim cover layer bull A 40-mil LDPE geomembrane liner will be installed on top of the compacted clay liner bull A geocomposite drainage layer will be installed over the geomembrane bull 12 inches of protective cover soil will be placed on top of the geocomposite bull A six (6)-inch vegetative soil layer will be installed on top of the protective cover bull The upper slope of the landfill is approximately 5 and the maximum side slope is 25

(41) bull The maximum elevation of the proposed modified final cover for the landfill is

approximately 283 NGVD at this cross-section Figure B2 is a typical cross section of the landfill slope that was used in the analysis Table B1 presents the strength parameters used in the analysis The values were taken from published data for the materials considered in the analysis For the earthquake load a horizontal acceleration of 02 g was used based on published data by the United States Geological Survey for the El Dorado Arkansas area (01 second surface acceleration 2 exceedance in 50 years 2008)

Page 2 of 3 532010

Table B1 Strength Parameters for Slope Stability Analysis

LayerSoil

Saturated Unit

Weight (pcf)

Internal Friction Angle

(degrees)

Cohesion (psf)

Interface Friction Angle

(degrees)

Interface Adhesion

(psf)

Vegetative Cover (1) 140 25 200

Compacted Clay (1) 120 25 500

Existing Intermediate Cover (1) 120 20 500

Geocomposite (2) 59 28 50

Geomembrane Liner (2) 57 25 0

Geosynthetic Clay Liner (3) 50 17 0

Protective Cover Soil (1) 100 30 0

Compacted Soil ldquoFoundationrdquo Layer (1)

100 23 500

Class 1 Waste (4) 70 36 300

Notes (1) Civil Engineering Reference Manual Sixth Edition Lindeburg MR Foundation

Engineering Handbook Second Edition Fang H-Y (2) GSE material data sheets (3) CETCO material data sheets (4) Bray et al (2009) ldquoShear Strength of Municipal Solid Wasterdquo Journal of Geotechnical and

Geoenvironmental Engineering June p 709-722 Summary of Analysis The GEO-SLOPE SlopeW 2007 computer program was used in the stability analysis Slope stability was assessed for both static and dynamic conditions The Ordinary and Modified Bishop Ordinary and Modified Janbu and Morgenstern-Price methods were used in determining stability A circular failure was analyzed for the sitersquos critical slope profile The minimum static and dynamic factors of safety were selected to represent the worst-case failure conditions for circular slope failure Table B2 presents a summary of the factor of safety (FS) against failure for both static and dynamic conditions for the circular failure mode

Page 3 of 3 532010

The minimum recommended FS against slope failure for static loading is 15 The minimum static FS of 48 occurred for a circular failure through the edge of the GCL liner system The minimum recommended FS against slope failure for dynamic loading is 10 The minimum dynamic FS of 23 occurred for a circular failure through the edge of the GCL liner system Based on the assessment the site design is stable with respect to circular failure in both static and dynamic conditions Figures B3 and B4 present the slope stability failure surface outputs

Table B2 Summary of Factor of Safety Values

Cover AlternativeFailure Mode Static Condition FS Dynamic Condition FS

Circular Failure 23 48

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

APPENDIX A GCL Settlement Articles

APPENDIX B Slope Stability Analysis

Page 1 of 3 532010

SUMMARY OF SLOPE STABILITY ANALYSIS WCA Union County Class 1 Landfill

Technical Approach The purpose of the stability analysis is to determine if the proposed design of the landfill is stable under both static and dynamic (earthquake) conditions Specifically the stability of a section of existing waste lined with a geosynthetic clay liner (GCL) then filled to a significant height with waste is evaluated Figure B1 presents the location of the most critical slope section of the Class 1 landfill which was used in the stability analysis This section corresponds with an area of maximum GCL-lined waste length and significant waste fill height Based on a review of existing documents for the landfill facility the following cross-section was developed for the analysis bull The existing Class 1 waste is filled to elevations ranging from 215 to 243 NGVD bull 18 inches of intermediate cover soil is in place over the existing Class 1 waste bull A portion of the existing waste (approximately 185 linear feet) in this cross-section will be

lined with the following materials (bottom to top) bull Six (6) inches of compacted soil to act as a foundation layer bull A geosynthetic clay liner (GCL) bull A 60-mil textured HDPE geomembrane bull Two (2) feet of protective cover soil

bull Class 1 waste will be filled to design grades with a layer of interim cover installed as a foundation layer for the construction of the final cap

bull An 18-inch thick compacted clay liner will be installed on top of the interim cover layer bull A 40-mil LDPE geomembrane liner will be installed on top of the compacted clay liner bull A geocomposite drainage layer will be installed over the geomembrane bull 12 inches of protective cover soil will be placed on top of the geocomposite bull A six (6)-inch vegetative soil layer will be installed on top of the protective cover bull The upper slope of the landfill is approximately 5 and the maximum side slope is 25

(41) bull The maximum elevation of the proposed modified final cover for the landfill is

approximately 283 NGVD at this cross-section Figure B2 is a typical cross section of the landfill slope that was used in the analysis Table B1 presents the strength parameters used in the analysis The values were taken from published data for the materials considered in the analysis For the earthquake load a horizontal acceleration of 02 g was used based on published data by the United States Geological Survey for the El Dorado Arkansas area (01 second surface acceleration 2 exceedance in 50 years 2008)

Page 2 of 3 532010

Table B1 Strength Parameters for Slope Stability Analysis

LayerSoil

Saturated Unit

Weight (pcf)

Internal Friction Angle

(degrees)

Cohesion (psf)

Interface Friction Angle

(degrees)

Interface Adhesion

(psf)

Vegetative Cover (1) 140 25 200

Compacted Clay (1) 120 25 500

Existing Intermediate Cover (1) 120 20 500

Geocomposite (2) 59 28 50

Geomembrane Liner (2) 57 25 0

Geosynthetic Clay Liner (3) 50 17 0

Protective Cover Soil (1) 100 30 0

Compacted Soil ldquoFoundationrdquo Layer (1)

100 23 500

Class 1 Waste (4) 70 36 300

Notes (1) Civil Engineering Reference Manual Sixth Edition Lindeburg MR Foundation

Engineering Handbook Second Edition Fang H-Y (2) GSE material data sheets (3) CETCO material data sheets (4) Bray et al (2009) ldquoShear Strength of Municipal Solid Wasterdquo Journal of Geotechnical and

Geoenvironmental Engineering June p 709-722 Summary of Analysis The GEO-SLOPE SlopeW 2007 computer program was used in the stability analysis Slope stability was assessed for both static and dynamic conditions The Ordinary and Modified Bishop Ordinary and Modified Janbu and Morgenstern-Price methods were used in determining stability A circular failure was analyzed for the sitersquos critical slope profile The minimum static and dynamic factors of safety were selected to represent the worst-case failure conditions for circular slope failure Table B2 presents a summary of the factor of safety (FS) against failure for both static and dynamic conditions for the circular failure mode

Page 3 of 3 532010

The minimum recommended FS against slope failure for static loading is 15 The minimum static FS of 48 occurred for a circular failure through the edge of the GCL liner system The minimum recommended FS against slope failure for dynamic loading is 10 The minimum dynamic FS of 23 occurred for a circular failure through the edge of the GCL liner system Based on the assessment the site design is stable with respect to circular failure in both static and dynamic conditions Figures B3 and B4 present the slope stability failure surface outputs

Table B2 Summary of Factor of Safety Values

Cover AlternativeFailure Mode Static Condition FS Dynamic Condition FS

Circular Failure 23 48

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

APPENDIX B Slope Stability Analysis

Page 1 of 3 532010

SUMMARY OF SLOPE STABILITY ANALYSIS WCA Union County Class 1 Landfill

Technical Approach The purpose of the stability analysis is to determine if the proposed design of the landfill is stable under both static and dynamic (earthquake) conditions Specifically the stability of a section of existing waste lined with a geosynthetic clay liner (GCL) then filled to a significant height with waste is evaluated Figure B1 presents the location of the most critical slope section of the Class 1 landfill which was used in the stability analysis This section corresponds with an area of maximum GCL-lined waste length and significant waste fill height Based on a review of existing documents for the landfill facility the following cross-section was developed for the analysis bull The existing Class 1 waste is filled to elevations ranging from 215 to 243 NGVD bull 18 inches of intermediate cover soil is in place over the existing Class 1 waste bull A portion of the existing waste (approximately 185 linear feet) in this cross-section will be

lined with the following materials (bottom to top) bull Six (6) inches of compacted soil to act as a foundation layer bull A geosynthetic clay liner (GCL) bull A 60-mil textured HDPE geomembrane bull Two (2) feet of protective cover soil

bull Class 1 waste will be filled to design grades with a layer of interim cover installed as a foundation layer for the construction of the final cap

bull An 18-inch thick compacted clay liner will be installed on top of the interim cover layer bull A 40-mil LDPE geomembrane liner will be installed on top of the compacted clay liner bull A geocomposite drainage layer will be installed over the geomembrane bull 12 inches of protective cover soil will be placed on top of the geocomposite bull A six (6)-inch vegetative soil layer will be installed on top of the protective cover bull The upper slope of the landfill is approximately 5 and the maximum side slope is 25

(41) bull The maximum elevation of the proposed modified final cover for the landfill is

approximately 283 NGVD at this cross-section Figure B2 is a typical cross section of the landfill slope that was used in the analysis Table B1 presents the strength parameters used in the analysis The values were taken from published data for the materials considered in the analysis For the earthquake load a horizontal acceleration of 02 g was used based on published data by the United States Geological Survey for the El Dorado Arkansas area (01 second surface acceleration 2 exceedance in 50 years 2008)

Page 2 of 3 532010

Table B1 Strength Parameters for Slope Stability Analysis

LayerSoil

Saturated Unit

Weight (pcf)

Internal Friction Angle

(degrees)

Cohesion (psf)

Interface Friction Angle

(degrees)

Interface Adhesion

(psf)

Vegetative Cover (1) 140 25 200

Compacted Clay (1) 120 25 500

Existing Intermediate Cover (1) 120 20 500

Geocomposite (2) 59 28 50

Geomembrane Liner (2) 57 25 0

Geosynthetic Clay Liner (3) 50 17 0

Protective Cover Soil (1) 100 30 0

Compacted Soil ldquoFoundationrdquo Layer (1)

100 23 500

Class 1 Waste (4) 70 36 300

Notes (1) Civil Engineering Reference Manual Sixth Edition Lindeburg MR Foundation

Engineering Handbook Second Edition Fang H-Y (2) GSE material data sheets (3) CETCO material data sheets (4) Bray et al (2009) ldquoShear Strength of Municipal Solid Wasterdquo Journal of Geotechnical and

Geoenvironmental Engineering June p 709-722 Summary of Analysis The GEO-SLOPE SlopeW 2007 computer program was used in the stability analysis Slope stability was assessed for both static and dynamic conditions The Ordinary and Modified Bishop Ordinary and Modified Janbu and Morgenstern-Price methods were used in determining stability A circular failure was analyzed for the sitersquos critical slope profile The minimum static and dynamic factors of safety were selected to represent the worst-case failure conditions for circular slope failure Table B2 presents a summary of the factor of safety (FS) against failure for both static and dynamic conditions for the circular failure mode

Page 3 of 3 532010

The minimum recommended FS against slope failure for static loading is 15 The minimum static FS of 48 occurred for a circular failure through the edge of the GCL liner system The minimum recommended FS against slope failure for dynamic loading is 10 The minimum dynamic FS of 23 occurred for a circular failure through the edge of the GCL liner system Based on the assessment the site design is stable with respect to circular failure in both static and dynamic conditions Figures B3 and B4 present the slope stability failure surface outputs

Table B2 Summary of Factor of Safety Values

Cover AlternativeFailure Mode Static Condition FS Dynamic Condition FS

Circular Failure 23 48

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

Page 1 of 3 532010

SUMMARY OF SLOPE STABILITY ANALYSIS WCA Union County Class 1 Landfill

Technical Approach The purpose of the stability analysis is to determine if the proposed design of the landfill is stable under both static and dynamic (earthquake) conditions Specifically the stability of a section of existing waste lined with a geosynthetic clay liner (GCL) then filled to a significant height with waste is evaluated Figure B1 presents the location of the most critical slope section of the Class 1 landfill which was used in the stability analysis This section corresponds with an area of maximum GCL-lined waste length and significant waste fill height Based on a review of existing documents for the landfill facility the following cross-section was developed for the analysis bull The existing Class 1 waste is filled to elevations ranging from 215 to 243 NGVD bull 18 inches of intermediate cover soil is in place over the existing Class 1 waste bull A portion of the existing waste (approximately 185 linear feet) in this cross-section will be

lined with the following materials (bottom to top) bull Six (6) inches of compacted soil to act as a foundation layer bull A geosynthetic clay liner (GCL) bull A 60-mil textured HDPE geomembrane bull Two (2) feet of protective cover soil

bull Class 1 waste will be filled to design grades with a layer of interim cover installed as a foundation layer for the construction of the final cap

bull An 18-inch thick compacted clay liner will be installed on top of the interim cover layer bull A 40-mil LDPE geomembrane liner will be installed on top of the compacted clay liner bull A geocomposite drainage layer will be installed over the geomembrane bull 12 inches of protective cover soil will be placed on top of the geocomposite bull A six (6)-inch vegetative soil layer will be installed on top of the protective cover bull The upper slope of the landfill is approximately 5 and the maximum side slope is 25

(41) bull The maximum elevation of the proposed modified final cover for the landfill is

approximately 283 NGVD at this cross-section Figure B2 is a typical cross section of the landfill slope that was used in the analysis Table B1 presents the strength parameters used in the analysis The values were taken from published data for the materials considered in the analysis For the earthquake load a horizontal acceleration of 02 g was used based on published data by the United States Geological Survey for the El Dorado Arkansas area (01 second surface acceleration 2 exceedance in 50 years 2008)

Page 2 of 3 532010

Table B1 Strength Parameters for Slope Stability Analysis

LayerSoil

Saturated Unit

Weight (pcf)

Internal Friction Angle

(degrees)

Cohesion (psf)

Interface Friction Angle

(degrees)

Interface Adhesion

(psf)

Vegetative Cover (1) 140 25 200

Compacted Clay (1) 120 25 500

Existing Intermediate Cover (1) 120 20 500

Geocomposite (2) 59 28 50

Geomembrane Liner (2) 57 25 0

Geosynthetic Clay Liner (3) 50 17 0

Protective Cover Soil (1) 100 30 0

Compacted Soil ldquoFoundationrdquo Layer (1)

100 23 500

Class 1 Waste (4) 70 36 300

Notes (1) Civil Engineering Reference Manual Sixth Edition Lindeburg MR Foundation

Engineering Handbook Second Edition Fang H-Y (2) GSE material data sheets (3) CETCO material data sheets (4) Bray et al (2009) ldquoShear Strength of Municipal Solid Wasterdquo Journal of Geotechnical and

Geoenvironmental Engineering June p 709-722 Summary of Analysis The GEO-SLOPE SlopeW 2007 computer program was used in the stability analysis Slope stability was assessed for both static and dynamic conditions The Ordinary and Modified Bishop Ordinary and Modified Janbu and Morgenstern-Price methods were used in determining stability A circular failure was analyzed for the sitersquos critical slope profile The minimum static and dynamic factors of safety were selected to represent the worst-case failure conditions for circular slope failure Table B2 presents a summary of the factor of safety (FS) against failure for both static and dynamic conditions for the circular failure mode

Page 3 of 3 532010

The minimum recommended FS against slope failure for static loading is 15 The minimum static FS of 48 occurred for a circular failure through the edge of the GCL liner system The minimum recommended FS against slope failure for dynamic loading is 10 The minimum dynamic FS of 23 occurred for a circular failure through the edge of the GCL liner system Based on the assessment the site design is stable with respect to circular failure in both static and dynamic conditions Figures B3 and B4 present the slope stability failure surface outputs

Table B2 Summary of Factor of Safety Values

Cover AlternativeFailure Mode Static Condition FS Dynamic Condition FS

Circular Failure 23 48

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

Page 2 of 3 532010

Table B1 Strength Parameters for Slope Stability Analysis

LayerSoil

Saturated Unit

Weight (pcf)

Internal Friction Angle

(degrees)

Cohesion (psf)

Interface Friction Angle

(degrees)

Interface Adhesion

(psf)

Vegetative Cover (1) 140 25 200

Compacted Clay (1) 120 25 500

Existing Intermediate Cover (1) 120 20 500

Geocomposite (2) 59 28 50

Geomembrane Liner (2) 57 25 0

Geosynthetic Clay Liner (3) 50 17 0

Protective Cover Soil (1) 100 30 0

Compacted Soil ldquoFoundationrdquo Layer (1)

100 23 500

Class 1 Waste (4) 70 36 300

Notes (1) Civil Engineering Reference Manual Sixth Edition Lindeburg MR Foundation

Engineering Handbook Second Edition Fang H-Y (2) GSE material data sheets (3) CETCO material data sheets (4) Bray et al (2009) ldquoShear Strength of Municipal Solid Wasterdquo Journal of Geotechnical and

Geoenvironmental Engineering June p 709-722 Summary of Analysis The GEO-SLOPE SlopeW 2007 computer program was used in the stability analysis Slope stability was assessed for both static and dynamic conditions The Ordinary and Modified Bishop Ordinary and Modified Janbu and Morgenstern-Price methods were used in determining stability A circular failure was analyzed for the sitersquos critical slope profile The minimum static and dynamic factors of safety were selected to represent the worst-case failure conditions for circular slope failure Table B2 presents a summary of the factor of safety (FS) against failure for both static and dynamic conditions for the circular failure mode

Page 3 of 3 532010

The minimum recommended FS against slope failure for static loading is 15 The minimum static FS of 48 occurred for a circular failure through the edge of the GCL liner system The minimum recommended FS against slope failure for dynamic loading is 10 The minimum dynamic FS of 23 occurred for a circular failure through the edge of the GCL liner system Based on the assessment the site design is stable with respect to circular failure in both static and dynamic conditions Figures B3 and B4 present the slope stability failure surface outputs

Table B2 Summary of Factor of Safety Values

Cover AlternativeFailure Mode Static Condition FS Dynamic Condition FS

Circular Failure 23 48

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

Page 3 of 3 532010

The minimum recommended FS against slope failure for static loading is 15 The minimum static FS of 48 occurred for a circular failure through the edge of the GCL liner system The minimum recommended FS against slope failure for dynamic loading is 10 The minimum dynamic FS of 23 occurred for a circular failure through the edge of the GCL liner system Based on the assessment the site design is stable with respect to circular failure in both static and dynamic conditions Figures B3 and B4 present the slope stability failure surface outputs

Table B2 Summary of Factor of Safety Values

Cover AlternativeFailure Mode Static Condition FS Dynamic Condition FS

Circular Failure 23 48

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

WCA Union County Class 1 Landfill Slope Stability Typical Cross Section

Figure B2

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

4804Description WCA Union County Class 1 Landfill Comments Circular Failure - StaticAnalysis Method Janbu

Figure B3

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02

2315Description WCA Union County Class 1 Landfill Comments Circular Failure - DynamicAnalysis Method Janbu

Figure B4

Compacted Clay Cap

Compacted Soil Layer

Class 1 Waste

Geomembrane

Geomembrane

Vegetative and Protective Cover

Protective Cover

Geosynthetic Clay Liner

Existing Intermediate Cover

Existing Class 1 Waste

Geocomposite

Distance feet

0 50 100 150 200 250 300 350 400 450 500 550

Ele

vatio

n fe

et

170

180

190

200

210

220

230

240

250

260

270

280

290

• WCA Union County Cell 12 GCL Summarypdf
• • WCA Union County Slope Stability 5-3-10pdf
  • • 1 Summary of Stability Analysis
    • 2 Fig 1 - Section Location
    • 3 Fig 2 - Union County Slope Cross Section
    • 4 Fig 3 - Union County Circular Static
    • 5 Fig 4 - Union County Circular Dynamic
    • • 6533-052-FG01pdf
      • • 6533-052-FG01
        • • 6533-052-FG02pdf
          • • 6533-052-FG02