Boyd Ramsey, GSE Chief Engineer

Geomembrane, Geosynthetic Clay 

Liner and Composite Liners for Coal 

Ash Waste Containment 

18 October, 2012 Chantilly, VA

Global Footprint 

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Products 

Geomembranes 

Geomembranes are the most 

widely used products for solid 

waste containment (such as 

landfill liners), mining, and water 

containment applications. 

GeoSynthetic 

Clay Liners 

Geosynthetic clay liners (GCLs) combine 

geosynthetics with sodium bentonite clay 

to form a highly impermeable barrier that 

often replaces thick layers of expensive 

compacted clay. 

Geonets and 

Geocomposites 

GSE offers a broad range of quality 

geonet and geocomposite drainage 

liners designed to complement or 

replace sand, stone and gravel. 

Geotextiles 

GSE produces the most uniform, 

consistent and versatile nonwoven 

geotextile products on the market. 

Our products are available in many 

weights and thicknesses to meet your 

specific project requirements. 

Concrete Protection 

Protect your investments 

with GSE StudLiner, a line of high 

density polyethylene (HDPE) concrete 

protection products with studs on one 

side that lock the liner into the surface to 

prolong the life of the concrete. 

Specialty Products 

GSE has developed specialty products 

to provide for unique solutions. Whether 

it is for environmental, aquaculture, civil, 

tunnel or other demanding applications, 

GSE products are easy to install and 

built to last. 

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About Us 

Success is always a collaborative effort 

• GSE offers the largest capacity and widest selection of 

smooth or textured polyethylene geomembranes in the 

industry. 

• No other manufacturer offers a broader line of specialty 

products to meet unique needs. 

• Several of our product lines were launched as a direct 

result of collaboration with our customers to help them 

solve complex problems. 

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Geosynthetic Barrier Materials and Regulations 

needed. 

In December 2008 a 

levee containing coal 

ash failed at a TVA 

facility in Kingston TN. 

Subsequent clean-up 

costs are in excess of 

1.4 billion US dollars. 

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Geosynthetic Barrier Materials Well-Recognized 

On 31 October 2011 a bluff on 

the We Energies Oak Creek 

power plant site collapsed, 

spilling coal ash into Lake 

Michigan 

On 1 March 2012 WDNR 

issued NOV 

“Lack of lining in pond blamed in 

bluff collapse at We Energies site” .. 

Milwaukee Journal Sentinel 

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USEPA documented groundwater contamination 

sites (coal ash storage) 

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Subtitle D liner system 

Leachate Removal System 

(i.e. perforated pipe network) 

≥ 12” 

≥ 24” 

Solid Waste 

Filter Layer 

Permeability ≥1x10 -2 cm/sec 

Permeability ≤1x10 -7 cm/sec 

Soil Subgrade 

EPA Minimum 

Technical Guidance 

Leachate Collection 

Geomembrane ≥ 30 mils 

if HDPE then ≥ 60 mils 

Compacted Clay Liner (CCL) 

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Subtitle D cover system 

≥ 6” 

≥ 18” 

Top Soil 

Permeability 

k ≤ bottom liner ≤ 1x10 -5 cm/sec 

Gas Vent (if necessary) 

Solid Waste 

Geomembrane ≥ 20 mils 

if HDPE, ≥ 40 mils is most common 

Compacted Clay Liner (CCL) 

EPA Minimum 

Technical Guidance 

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Geosynthetic Clay Liners (GCLs) 

GM 

GM/CCL 

GM/GCL 

“Leak detection system flow rates attributable to 

leakage through GM/CCL and GM/GCL/CCL primary 

liners constructed with CQA are probably similar to 

those for GM/GCL primary liners constructed with 

CQA.”

HIGH 

PERFORMANCE 

GEOMEMBRANE

Differentiation 

Best 

Better 

Good 

High Performance 

Industry Standard 

Products 

Purpose-driven 

Products 

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What must a High Performance geomembrane do? 

Last longer 

More durable 

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What must a High Performance geomembrane do? 

Break Elongation 

Multi-axial Break Resistance 

High Pressure Oxidative Induction Time (HPOIT) 

HPOIT Retention 

UV Resilience 

Environmental Stress Crack Resistance 

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How? 

Raw material selection 

Resin 

Additives 

Carbon Black 

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Selecting the Right Resin 

Break Elongation 

Multi-axial Resistance 

Stress Crack Resistance 

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HPOIT (minutes) 

Selecting the Right Additives 

High Density: 

Linear Low Density: 

+100% +38% 

HPOIT (minutes) 

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Oven Aging 

High Density: 

+100% 


+83% 

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UV Aging 

High Density: 

+220% 


+214% 

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Multi-axial Performance 

True performance test 

Differential settlement causes at 

least 20% 

Defects and flaws can cause 

poor performance 

Structured geomembranes 

struggle 

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High Pressure Oxidative Induction Time 

Measures additives active at 

field conditions 

Why? 

The test operates at a lower 

temperature 

A temperature where the 

additives are active 

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What is Leak Location Geomembrane Liner? 

• Co-extrusion Process – allows for variety of surface layers 

– Textured or Smooth 

– Black, White, Green, and Conductive: 

Example: 1.5 mm GSE Conductive White Geomembrane 

White ≈ 0.13 mm 

Standard Black ≈ 1.32 mm 

Conductive ≈ .08 mm 

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SKB Lansing Landfill Project 

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APPLICATIONS 

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Landfill Closures 

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Mining 

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Exposed Applications 

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Hazardous Waste 

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Tunnels 

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Harsh Conditions 

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GSE COAL ASH 

RESISTANT GCL

Coal Ash Leak Location Liner System 

GSE Coal Ash Drain Geocomposite 

(Reduces or replaces aggregate leachate 

collection layer and graded filter) 

GSE Leak Location Liner 

(Spark testable geomembrane) 

GSE Coal Ash Resistant GCL 

(Polymer enhanced geosynthetic clay liner)


• Consistent Low Permeability 

Hydraulic Barrier 

• Superior Performance Alternative 

to Compacted Clay Liner 

• Protects Geomembrane from 

Puncture 

• Reduced Installation Cost and 

Time 

• Saves Airspace 

• Self-Sealing Properties 

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GCL Hydraulic Conductivity 

• Unlike compacted clays, GCL 

permeability varies with effective stress. 

• The greater the effective stress (load) 

the lower the GCL’s permeability. 

• Can vary as much as 10X in landfill 

bottom liners, i.e. as constructed to final 

fill. 

• Hydraulic Conductivity 

‒ ASTM D5887 

‒ Effective Confining Stress is 5 psi 

‒ Typical Value is 3 x 10 -9 cm/sec 

* Petrov, R.J. et al (1997) “Equations for Calculating the Rate of Liquid Migration Through Composite Liners Due to Geomembrane Defects”. 

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Compacted Clay Liners (CCLs) 

75 Feet 

1 x 10 -5 cm/s = 4% of area and 50.3% of flow 



• 10,000x range of permeability values. 

30 

Feet 


• Much of the test area failed to meet 1 x 10 -7 cm/sec requirement. 

Rogowski, 1990 

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“Assessment and Recommendations for 

Improving the Performance of Waste 

Containment Systems”, 

R. Bonaparte, D.E. Daniel, and R.M. Koerner, 

EPA/600/R-02/099, 

http://www.epa.gov/nrmrl/pubs/600r02099.pdf 

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Compacted Clay Liners - Objectives 

• Measure in-situ Performance 

• Focus – Hydraulic Conductivity 

• Design & Construction Variables – 

Determine impacts 

• Meeting Regulatory Requirements? 

• Meeting Design Objectives? 

• Cover Applications 

• Document Performance 

• Survivability 

• Settlement Impact 

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Compacted Clay Liners - Findings 

• 89 CCL Sites 

• Specified – 1 x 10E-7 cm/s 

• 25% Failed. 

• Why? – Failure to compact within 

the specified moisture zone and 

dry density. 

• Cover Failure – Desiccation 

occurs without GM liner and low 

Hydraulic Conductivity is lost 

within a few years of placement. 

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GM 

GM/CCL 

GM/GCL 

“Leak detection system flow rates attributable to 

leakage through GM/CCL and GM/GCL/CCL primary 

liners constructed with CQA are probably similar to 

those for GM/GCL primary liners constructed with 

CQA.”

Geosynthetic Clay Liners – Advantages 

• Self-healing Properties 

• Superior Hydraulic Conductivity to CCLs 

• Low Material & Installation Costs 

• Quick & Easy Installation 

• Low Volume Occupied Relative to CCLs 

• Withstand Differential Settlement 

• Self-heal After Desiccation 

• Resistance to Damaging Freeze/Thaw 

Effects 

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Geosynthetic Clay Liners – Disadvantages 

• Bentonite Chemical Alterations – 

• Free available Calcium & Magnesium 

• Low Overburden Stresses 

• Final Cover Systems 

• Slope Stability When Hydrated 

• Low Bentonite Hydrated Shear Strength 

• Internal reinforcement 

• Peel Strength 

• Thickness 

• ~10 mm Thick 

• Vulnerable to puncture 

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GCL Product Types 

Sodium bentonite 


GSE BentoLiner - Fabric Encased GCL 

Nonwoven geotextile 

Woven or nonwoven 

geotextile 

GSE GundSeal - Geomembrane Supported GCL 

Geomembrane 

Giroud Leakage Equation and Contact Factor-C: 

Q GM = C [1 + 0.1(h w / t) 0.95 ] a 0.1 h w 0.9 ks 0.74 

Where C varies from 0.01 (excellent) to 1.15 (poor contact) 

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Geomembrane Supported GCL 

• Provides swelling and sealing of bentonite clay with the chemical resistance and 

impermeability of HDPE geomembrane 

• 15 mil to 80 mil smooth or textured geomembrane 

• Installed in a single composite mode or encapsulated mode 

Geomembrane 

Sodium Bentonite 

Spunbonded Geotextile

Contact Factor 

Geotextile Encased GCL: Relative Good Hydraulic Contact 

GSE GundSeal: Bentonite Side Down, Excellent Hydraulic Contact 

Giroud Leakage Equation and Contact Factor-C: 

Q GM = C [1 + 0.1(h w / t) 0.95 ] a 0.1 h w 0.9 ks 0.74 

Where C varies from 0.01 (excellent) to 1.15 (poor contact)

Encapsulated Mode 

• Two product installation 

• Accepted U.S. and International liner system since 1991 

• Improved leakage performance over geomembrane/CCL liner 

• Improved slope performance 

• Prevents bentonite prehydration

GCL Product Types 



GSE BentoLiner - Fabric Encased GCL 



geotextile 

GSE GundSeal - Geomembrane Supported GCL 

Geomembrane 

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GSE BentoLiner 

Fabric Encased GCL

Fabric Encased GCL 




geotextile 

GSE BentoLiner Geosynthetic Clay Liner Product Options 

1. EC – woven & 3 oz/SY non-woven 

2. NSL – woven & 6 oz non-woven geotextiles 

3. CNSL – nominal 5 mil thick PP-coated NSL 

4. LNSL – 3 mil HD geo-film laminated onto NSL 

5. NWLL – 3 oz scrim non-woven & 6 oz woven geotextiles 

6. NWL – one 6 oz non-woven and one 6 oz scrim nonwoven geotextile 

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BentoLiner Fabric Encased GCL 

• High Quality Wyoming Sodium Bentonite 

‒ High Free Swell 

‒ Low Fluid Loss 

• Manufacturing 

• Integral Scrim Reinforced – Inhibits panel shrinkage 

and seam separation 

• “Needle Free” Product 

• Shipping – High square footage per truck/container 

(~39,525 SF, 3,850 SM)

Coal Ash Resistant GCL 

GSE Polymer Enhanced Coal Ash Resistant GCL 

• High Quality Wyoming Sodium Bentonite 

‒ High Free Swell 

‒ Low Fluid Loss 

• Blended with Proprietary Long Chain Polymers 

‒ Expanding of the polymers reduces the space for water to travel 

around the sodium bentonite platelets 

‒ The polymers absorb components responsible for cation 

exchange, allowing fresh water to hydrate the sodium bentonite 

‒ Polymers are currently used in NSF Certified applications

Leachate Analysis with High Ionic Strength 

Acid Mine 

Drainage 

Solution 1 

Coal Ash 

Leachate 

Solution 2 

Cations mg/L mg/L 

Gypsum 

Leachate 

Solution 3 

Fly Ash/ 

FGD 

Leachate 

Solution 4 

Fly Ash/ 

Gypsum 

Leachate 

Solution 5 

mg/L mg/L mg/L 

Calcium 660 820 580 740 480 

Magnesium 4,000 340 220 6 530 

Potassium 660 30 14 410 93 

Sodium 670 82 78 240 2200 

Anions 

Chloride 8,600 1,300 250 1,200 980 

Sulfate 10,000 1,900 2,200 1,600 7600 

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Solution 1 – Acid Mine Drainage 

Hydraulic Conductivity (cm/sec) 

1.00E-06 

1.00E-07 

1.00E-08 

1.00E-09 

1.00E-10 

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136 141 146 151 156 161 166 171 

≈ 8 Pore Volumes (Standard Bentonite) 

≈ 7 Pore Volumes 

(CAR GCL) 

Days 


(CAR GCL) 

Solution 1 (10% Moisture) Solution 1 (50% Moisture) Solution 1 (std. bentonite) 

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Solution 2 – Coal Ash Landfill 


1.00E-06 

1.00E-07 

1.00E-08 

1.00E-09 

1 6 11 16 21 26 

Days 

Solution 2 (50% Moisture) 


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Solution 3 – Gypsum Leachate 


1.00E-06 

1.00E-07 

1.00E-08 

1.00E-09 

Days 

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 

≈ 1.21E-07 cm/sec 



Solution 3 BentoLiner CAR (10% Moisture) Solution 3 BentoLiner Std (10% Moisture) 

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Solution 4 – Fly Ash/FGD Leachate 


1.00E-06 

1.00E-07 

1.00E-08 

1.00E-09 

1.00E-10 

Days 

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 



Solution 4 BentoLiner Std (10% Moisture) Solution 4 BentoLiner CAR (10% Moisture) 

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Solution 5 – Fly Ash/Gypsum Leachate 


1.00E-06 

1.00E-07 

1.00E-08 

1.00E-09 

1.00E-10 

Days 

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 



Solution 5 BentoLiner Std (10% Moisture) Solution 5 BentoLiner CAR (10% Moisture) 

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Resources 

Depending on soil size and 

overburden loads, many products 

offered by GSE can be selected 

for geomembrane use and 

protection. 

A step-by-step design method is 

provided in this GSE Design 

Manual. 

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Resources 

Product selection for GSE’s GCL 

product lines with step-by-step 

design method is provided in this 

GSE GCL Design Manual. 

A section on GCL/CCL 

equivalency is included. 

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Resources 

Product selection for 

GSE’s Drainage product 

lines with step-by-step 

design methods and 

performance calculations 

is provided. 

Also available on line for iterative design work. 

www.gseworld.com 

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Boyd Ramsey, GSE Chief Engineer

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