&EPA
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati OH 45268
Technology Transfer
CERI-88-33
Requirements for
Hazardous Waste
Landfill Design,
Construction and
Closure
Presentations
June 20-21, 1988
San Francisco, CA
June 23-24, 1988
Seattle, WA
July 12-13, 1988
Dallas, TX
July 14-15, 1988
Chicago, IL
August 23-24, 1988
Denver, CO
August 25-26, 1988
Kansas City, MO
August 30-31, 1988
Philadelphia, PA
September 1-2, 1988
Atlanta, GA
September 13-14, 1988
New York, NY
September 15-16, 1988
Boston, MA
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Table of Contents
INTRODUCTION - BIOGRAPHIES
{In order of presentation)
Robert Landreth i
Sarah A. Hokanson ii
David Daniel iii
Gregory N. Richardson iv
Robert M. Koerner v
SESSION I - REGULATORY ASPECTS
Minimum Technology Guidance and Regulations
on Design of Hazardous Waste Landfills
Sarah Hokanson 1-1
SESSION II - LINER DESIGN
Clay Liners
David Daniels II-l
Flexible Membrane Liners
Gregory Richardson 11-31
SESSION III - COLLECTOR DESIGN
Elements in a Collector System
Robert Koerner I II-l
SESSION IV - COMPUTER SOFTWARE SUPPORT
HWERL Computer Programs
Robert Landreth IV-1
FLEX - Flexible Membrane Liner Advisory Expert System IV-5
Robert Landreth
-------
Table of Contents (continued)
SESSION IV - COMPUTER SOFTWARE SUPPORT (continued)
CARDS - Geotechnical Analysis for Review of Dike Stability IV-9
Gregory Richardson
HELP - Hydrologic Evaluation of Landfill Performance Model IV-13
Gregory Richardson
GM - Geosynthetic Design Guidance for Hazardous Waste Landfill
Cells and Surface Impoundments IV-17
Gregory Richardson and Robert Koerner
SOILINER
David Daniel IV-23
SESSION V - CLOSURE DESIGN
Securing a Completed Landfill
Gregory Richardson V-l
SESSION VI - CONSTRUCTION, QUALITY ASSURANCE AND CONTROL
Construction of Clay Liners
David Daniel VI-1
Construction of Flexible Membrane Liners
Gregory Richardson VI-19
SESSION VII - LINER COMPATIBILITY WITH WASTES
Chemical Compatibility
Robert Landreth VII-1
SESSION VIII - LONG-TERM CONSIDERATIONS
Long-Term Considerations and Unknowns
Robert Koerner VIII-1
SESSION IX - LEAK RESPONSE ACTION PLAN
Response Action Plan for Leakage in Hazardous Waste Landfills
Sarah Hokanson IX-1
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Table of Contents (continued)
APPENDIX A
References
APPENDIX B
EPA - Hazardous Waste Management System; Minimum Technology Requirements
APPENDIX C
EPA - Liners and Leak Detection for Hazardous Waste Land Disposal Units;
Notice of Proposed Rulemaking. (Cover page only)
APPENDIX D
Analysis and Fingerprinting of Unexposed and Exposed Polymeric Membrane
Liners
APPENDIX B
Draft RCRA Guidance Document Landfill Design - Final Cover
APPENDIX F
Installation and Operation Instructions for the Sealed-Double Ring
Infiltrometer
APPENDIX G
Earthen Liners for Land Disposal Facilities
APPENDIX H
Laboratory Testing of Geosynthetics and Plastic Pipe For Double-Liner
Systems
APPENDIX I
Method 9090 - Compatibility Test for Wastes and Membrane Liners
APPENDIX J
Method 9100 - Saturated Hydraulic Conductivity, Saturated Leachate
Conductivity, and Intrinsic Permeability
-------
BIOGRAPHIES
-------
ROBERT LANDRETH
Robert Landreth is an Environmental Engineer at the EPA Hazardous Waste
Engineering Research Laboratory. He directs technical and administrative
aspects of extramural research projects on solid and hazardous waste
pollution, including multimedia research to establish disposal guidelines and
standards for flexible membrane liners in waste management facilities.
Mr. Landreth works closely with the land disposal division of EPA's Office
of Solid Waste in developing RCRA guidance. He assembled and guided a team in
developing guidance on use of double liners and developed four technical
resource documents related to RCRA. He holds B.S. and M.S. degrees in Civil
Engineering.
-------
SARAH A. HORANSON
Sarah A. Hokanson is a Project Geologist at The Earth Technology
Corporation in Washington, D.C. She has assisted EPA's Office of Solid Waste
in writing regulations and background and guidance documents for the Double
Liner Rule, the Proposed Leak Detection Rule, and the No Migration Rule. In
the course of this work, she has developed an in-depth understanding of these
and other RCRA regulations and their planned implementation.
In addition to her policy work, Ms. Hokanson has participated in R & D
projects and field studies in the areas of ground-water management, exposure
and risk assessment, and Superfund remedial technologies (stabilization and
soil washing). She has investigated and inspected over 50 hazardous waste
landfills, surface impoundments, and waste piles as part of RCRA facility
assessments, environmental auditing, and Part B permit reviews.
Ms. Hokanson holds a B.A. degree in Geology/Chemistry from Wellesley
College and an M.S. degree in Geology from Brown University.
-------
DAVID DANIEL
David Daniel is an Associate Professor of Civil Engineering at the
University of Texas at Austin. Since 1981 his research has focused on the
hydraulic conductivity and permeability of earth materials, and the use of
earth liners for landfills and impoundments. The research has been sponsored
by the U.S. Environmental Protection Agency, the Chemical Manufacturers
Association, the National Science Foundation, and others.
Professor Daniel has also served as a consultant to various industries and
agencies involving approximately fifteen hazardous waste disposal facilities
in the United States. His honors include the Norman and Croes Medals from
ASCE. He holds B.S., M.S., and Ph.D. degrees in Civil Engineering from the
University of Texas.
-------
GREGORY N. RICHARDSON
Gregory Richardson is a corporate engineer with S&ME, a part of
Westinghouse Environmental Engineering which includes Thermal Technologies,
Hazardous Waste Cleanup, and Full Engineering Service. He works at the
division level to support and audit the technical role of all S&ME units.
Dr. Richardson's areas of specialization include: landfill design,
underground storage tanks, geosynthetics, and earthquake engineering. He
holds a Ph.D. in Geotechnical Engineering from the University of California.
-------
ROBERT N. KOERNER
Robert M. Koerner is an H.L. Bowman Professor of Civil, Engineering at
Drexel University in Philadelphia. He teaches Geotechnical and Geosynthetics
Engineering, concentrates on Geosynthetic research, and is Director of the
Geosynthetic Research Institute. He is the author of numerous publications,
reports, and books focusing on Geotechnical and Geosynthetic systems.
Dr. Koerner holds a Ph.D from Duke University.
-------
SESSION I - REGULATORY ASPECTS
Sarah Hokanson
-------
MINIMUM TECHNOLOGY GUIDANCE AND
REGULATIONS ON DESIGN OF
HAZARDOUS WASTE LANDFILLS
Sarah Hokanson
The Earth Technology Corporation
REGULATORY BACKGROUND
Minimum Technological Requirements
• Provisions set forth in RCRA Section 3004(o), as
amended by HSWA of 1984.
Areas Covered by Minimum Technology Regulations and
Guidance
• Double Liners and Leachate Collection/Removal Systems
• Leak Detection Systems
Additional Areas Covered by Proposed Regulations and
Guidance
• Construction Quality Assurance
• Cover Design
• Response Action Plan for Leakage in Landfills
1-1
-------
ERA'S PHILOSOPHY
Performance Goal for Landfills
• Prevent hazardous constituent migration out of the
landfill (through post-closure care).
EPA's Approach - Liquids Management Strategy
• Minimize leachate generation (through cover design).
• Maximize leachate collection and removal (through liners
and LCRS).
GUIDANCE AND REGULATIONS ISSUED TO DATE
Double Liners and LCRS
• Codification Rule (July 15, 1985)
• Draft Minimum Technology Guidance (May 24, 1985)
• Proposed Rule (March 28, 1986)
• Notice of Availability of Information and Request for
Comments (April 17, 1987)
GUIDANCE AND REGULATIONS ISSUED TO DATE
(continued)
Leak Detection Systems
• Proposed Rule (May 29, 1987)
Construction Quality Assurance
• Proposed Rule (May 29, 1987)
• Technical Guidance Document (October 1986)
Response Action Plan
• Proposed Rule (May 29, 1987)
Cover Design
• Draft Guidance (July 1982)
CURRENT SCHEDULE FOR MINIMUM TECHNOLOGY
GUIDANCE AND REGULATIONS*
• October 1988: Guidance on Cover Design
• June 1989: Final Double Liner Rule
Final Leak Detection Rule
-- Construction Quality Assurance
-- Response Action Plan
* Subject to change, especially in an election year.
1-2
-------
Overview of Existing and Projected Future Regulations
Covering the Four Areas Shown Below:
COVERS
FOUNDATIONS
>CQA
DOUBLE LINERS AND LCRS
LEAK DETECTION SYSTEM
-------
LEACHATE COLLECTION
AND REMOVAL SYSTEM
LEACHATE DETECTION,
COLLECTION, AND
REMOVAL SYSTEM (LOCKS
DOUBLE LINERS AND LEACHATE COLLECTION SYSTEM
Components
PROTECTIVE SOIL OR
COVER (Optional)
— Drain pipe (TypJ
SOLID WASTE
DRAINAGE
MATERIAL Q
DRAINAGE
MATERIAL .p <» * p * a
COMPACTED LOW-PERMEABILITY SOIL
NATIVE SOIL FOUNDATION
TOP LINER (FML)
BOTTOM
COMPOSITE LINER
Upper component
(FML)
Lower component
(compacted soil)
LEACHATE COLLECTION
SYSTEM SUMP
(Monitoring Compliance
Point)
Schematic of a Double Liner and Leachate Collection System for a
Landfill
Source: EMCON, 1987
-------
TYPES OF LINERS
• Flexible Membrane Liner (FML)
• Compacted Low Permeability Soil Liner
• Composite Liner (FML/Compacted Low Permeability Soil
Layer)
FML MINIMUM THICKNESS SPECIFICATIONS
(GUIDANCE)
Top Liner
• Minimum thickness without timely cover: 45 mil
• Minimum thickness with timely cover: 30 mil
Bottom Liner (Composite Liner)
• Minimum thickness: 30 mil & clay
These values, however, are not adequate for all FML
materials.
Most FML materials installed at landfills will range from
60-100 mil.
FML
Other Considerations When Selecting FML Materials
• Chemical Compatibility With Waste Leachate
• Aging/Durability Characteristics (resistance to
environmental stresses)
• Stress/Strain Characteristics
• Ease of Installation (placement, seaming)
• Water Vapor/Chemical Permeation
1-5
-------
COMPACTED LOW PERMEABILITY SOIL LINER
Materials
• Natural Soil Materials (e.g., Clays, Silts, Sands)
Material Selection Criteria
• Thickness Sufficient to Prevent Migration
• Low Hydraulic Conductivity (i.e., 1 x 10~7 cm/sec for
bottom liners)
Other Considerations
Plasticity Index
Atterburg Limits
Grain Sizes
Clay Mineralogy
Attenuation Properties
LEACHATE COLLECTION AND REMOVAL SYSTEMS
LCRS Components
• Drainage Layer
• Filters
• Cushions
• Sump
• Pipes/Appurtenances
LCRS DRAINAGE LAYER
Granular Drainage Materials
• Clean Sand or Gravel
Selection Criteria
• High Hydraulic Conductivity
• Low Capillary Tension
• Physically Compatible With FML (in cases where
in direct contact)
• Physically Compatible With Granular Filters or Cushions
1-6
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HYDRAULIC CONDUCTIVITIES OF GRANULAR MATERIALS
COEFFICIENT OF PERMEABILITY (Hydraulic Conductivity) IN CM/SEC
(Log scale)
io
i.o
ic
1
io~2
io
~3
io
~4
io
"5
icr6
10"
DRAINAGE
POTENTIAL
SOIL
TYPES
1
1 1
Good
Clean gravel
Clean sands, and
clean sand and
gravel mixtures
|
Poor
Almost
imper-
vious
Very fine sands, organic
and inorganic silts, mixtures
of sand, silt and clay, glacial
till, stratified clay deposits,
etc.
Adapted from Terzaghi and Peck (1967)
-------
CAPILLARY RISE AS A FUNCTION OF THE
HYDRAULIC CONDUCTIVITY OF GRANULAR
MATERIALS
Hydraulic Conductivity of
Drainage Medium (k) Capillary Rise (h)
cm/sec
1 x 1CT3
1 x 10~2
1
in
38.6
12.2
1.2
Source: EPA, May 1987
LCRS DRAINAGE LAYER
Synthetic Drainage Materials (Polypropylene, Polyester,
and Polyethylene)
• Nets (160-280 mils)
• Needle-Punched Nonwoven Geotextiles
(80-200 mils)
• Mats (400-800 mils)
• Corrugated, Waffled, or Alveolate Plates
(400-800 mils)
Selection Criteria
• High Hydraulic Transmissivities Under Expected Load
Conditions
• Chemical Compatibility With Waste Leachate
LCRS FILTER MATERIALS AND SPECIFICATIONS
Materials
Granular Filters (used with granular drainage materials)
-- Single granular layer
-- Graded, multiple granular layers
Geotextile Filters (used with both granular and synthetic
drainage material)
-- Nonwoven geotextiles (heat-bonded or needle-
punched) for fine grained soils
-- Woven monofilament geotextiles for sands
-------
Leachate
Subsoil
v = seepage velocity
r
ne = effective porosity
Time of Travel (TOT)
Leachate
Subsoil
.k = i£j
vs *'
L
II-9
-------
Leachate
.Concentration
of Solute = GO
Effluent
Concentration
of Solute = c
0
(torn = ne)
Dispersion
0 1 2
Pore Volumes of Flow
II-10
-------
ERA'S CURRENT POSITION ON DOUBLE LINER DESIGNS
• May delete the option to have a compacted soil bottom
liner in final rule.
• May specify liner designs.
• May allow the following double liner systems:
1. Top Liner: FML
Bottom Liner: Composite Liner
2, Top Liner: Composite Liner
Bottom Liner: Composite Liner
• May add variance from these designs for equivalent or
better liners.
RATIONALE FOR DELETING THE COMPACTED SOIL
BOTTOM LINER
Analytical and Numerical Studies (April 17, 1987)
• Composite bottom liner performs significantly better than
compacted soil bottom liner in:
-- Maximizing leachate collection and removal
-- Minimizing leakage through bottom liner over time.
Specific Performance Criteria
• Leachate Collection Efficiency
• Leak Detection Sensitivity
• Total Leakage Into and Out of the Bottom Liner
1-11
-------
BOTTOM LINER PERFORMANCE
COMPOSITE DESIGN
COMPACTED SOIL DESIGN
Breach in
Top Liner
Bottom Liner
Composite
Breach in
Top Liner
To sump °
0
10 Cf 0 O 0 0
V
0
0
0
°0
STT
o
Bottom Liner-
Compacted Soil
-------
COMPARISON OF LEAK DETECTION SENSITIVITIES
1000
ra
T3
O
a
\
ID
O
oc
UJ
z
0.
O
O
DC
X
UJ
O
CO
o
UJ
H
UJ
Q
I
2
Z
800
600
400
200
860
86
Y///////////A
0.001
Compacted soil
k -1 x 10"7cm/sec
Composite
(intact)
TYPE OF BOTTOM LINER
Comparison of leak detection sensitivity for 3-ft compacted soil and
composite liners (one-dimensional saturated flow calculations).
Source: 52 FR 12570, April 17, 1987
1-13
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COMPARISON OF LEACHATE COLLECTION EFFICIENCIES
100 -
o
z
111
111
z
o
o
111
o
o
HI
h-
<
x
o
Composite with
small FML holo
10 100 1,000 10,000
TOP LINER LEAKAGE RATE (Gal/acr»/day)
Comparison of leachate collection efficiencies for
compacted soil and composite bottom liners.
Source: 52 FR 12572, April 17, 1987
1-14
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CUMULATIVE LEAKAGE INTO THE BOTTOM LINER
200,000
o
ra
- 150,000
-------
LCRS DESIGN REQUIREMENTS
Proposed Rule (March 28, 1986)
• Designed to operate through the end of the
post-closure care period
• Chemically resistant to waste and leachate
• Sufficient strength and thickness to operate
• Function without clogging
• primary LCRS to cover the bottom of the unit
(side-wall coverage optional)
• Secondary LCRS to cover both bottom and side walls
APPLICABLE UNITS
Permit Applications Submitted
Before 11/8/84
New Facilities No
If permit
modified after
11/8/84: Yes
Interim Status
Facilities No
If permit
modified after
11/8/84: Yes
Permitted
Facilities
New units at
previously Interim
Status facilities: No*
After 11/8/84
New Facilities Yes
Interim Status
Facilities
Existing units: No
New units
(operational
after 5/8/85): Yes
Permitted
Facilities
New units at
previously Interim
Status facilities: Yes
" Proposing to require MTR for these units on site-
by-site basis.
PROPOSED MINIMUM DESIGN REQUIREMENTS FOR
LEAK DETECTION SYSTEM (LDCRS)
Drainage Layer
a. Granular:
-- Thickness >1 ft
-- Hydraulic conductivity > 1 cm/sec
b, Synthetic
- Hydraulic transmissivity > 5 x 10"4 rrrVsec
1-16
-------
Optional leachate
collection pipe
PROPOSED LEAK DETECTION SYSTEM
1-ft granular drainage layer—;
Compacted soil—,
,;..2%-m_m:,\'^. ;•;.':. Leak Detection System-.'•••:'•'•:•'2% mm '^_
I— PROTECTIVE SOIL COVER
- LEACHATE COLLECTION AND
REMOVAL SYSTEM (Above top liner)
| TOP LINER (Composite)
_ LEACHATE DETECTION,
COLLECTION, AND REMOVAL SYSTEM
I— BOTTOM LINER (Composite)
L1-ft granular drainage layer
(k > 1 cm/sec)
•3-ft min. compacted soil
(ks 1 x 10'7 cm/sec)
LEGEND
Geotextile
(synthetic fibers-woven, non woven or knit)
Geonet
(plastics formed into an open, netlike
configuration (used here in a redundant manner))
Flexible Membrane Liner (FML)
-------
PROPOSED MINIMUM DESIGN REQUIREMENTS FOR
LDCRS (continued)
Bottom Slope
Minimum of 2 percent
Sump
"Appropriate size" to:
• Meet detection performance criteria
• Allow daily monitoring and measurement
• Minimize head on the bottom liner.
PROPOSED DESIGN PERFORMANCE REQUIREMENTS
Standard Values
Leak Detection Sensitivity: 1 gpad (steady-state)
Detection Time: 1 day (steady-state)
Basis for Standard Values
• Analytical and Numerical Studies for Leakage
Through FMLs
• Field Performance Data From Newly Constructed
Landfills
1-18
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PROPOSED DESIGN PERFORMANCE REQUIREMENTS
(continued)
Demonstration to Meet Design Standards
(Future Guidance)
• For detection sensitivity, calculate flow rates
assuming uniform top liner leakage. (Disregard
stored liquids in LCRS.)
• For detection time, consider drain spacing, drainage
media, bottom slope, top and bottom liners.
Calculate detection time for worst-case scenario
(longest flow path to detection point).
APPLICABLE UNITS
Units
• Landfills
• Surface Impoundments
• Waste Piles
HSWA Section 3004 (0)(4)(B)(ii)
• Units on which construction begins after
promulgation date of final rule (scheduled for
June 1989)
Proposed Effective Date
• 6 Months After Promulgation
GUIDANCE ON FINAL COVER
(July 1982)
1-19
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FINAL COVER
Current Regulations (July 1982)
• Cover designed to minimize precipitation infiltration,
• No more permeable than liner system,
• Must operate with minimum maintenance.
• Designed to accommodate settlement and subsidence.
FINAL COVER (continued)
Existing Guidance (July 1982)
• Final cover should be placed over each cell as it is
completed.
• Cover design should have the following components:
-- Vegetative Cover
-- Drainage Layer
-- Composite Liner (FML/Compacted Soil).
COVER DESIGN
Vegetative Cover
• Thickness > 2 ft
• Minimal erosion and maintenance (e.g., fertilization,
irrigation)
• Vegetative root growth not to extend below 2 ft
• Final top slope between 3 and 5% after settlement or
subsidence. Slopes greater than 5% not to exceed 2,0
tons/acre erosion (USDA Universal Soil Loss Equation)
• Surface drainage system capable of conducting run-off
across-cap without-rills and guHies
1-20
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COVER DESIGN
Drainage Layer Design
• Thickness > 1 ft
• Saturated hydraulic conductivity > 10"3 cm/sec
• Bottom Slope > 2% (after settlement/subsidence)
• Overlain by graded granular or synthetic filter to prevent
clogging
• Allow lateral flow and discharge of liquids
COVER DESIGN
Low Permeability Liner Design
FML Component:
• Thickness > 20 mil
• Final upper slope > 2% (after settlement)
• Located wholly below the average depth of frost
penetration in the area
Soil Component:
• Thickness > 2 ft
• Saturated hydraulic conductivity < 1 x 10~7 cm/sec
• Installed in 6-in lifts
FINAL COVER GUIDANCE
Settlement/Subsidence of Wastes
Not specifically addressed in existing guidance
1-21
-------
CONSTRUCTION QUALITY ASSURANCE
PROGRAM
Proposed Regulations (May 29, 1987)
and Existing Guidance
NEED FOR CQA REGULATIONS AND GUIDANCE
EPA Study (1983)
• Construction-related problems during liner systems
installation were a predominant cause of liner
system failure.
• Rigorous CQA could have identified the
problem.
Another EPA Study (1985) of 27 Landfills and Surface
Impoundments
• A Proper Philosophical Approach
• A Formal QA Program
Basis for CQA Program
• Performance standards proposed in the rule
• CQA guidance
CQA PROGRAM
Program Elements
• CQA Plan Submitted by Owner/operator
• Implementation of CQA Plan by Independent Third Party
• Submission of CQA Reports by Owner/operator
• Review of Selected CQA Reports by EPA
1-22
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CQA PLAN
Plan Elements
• Responsibility and Authority
• CQA Personnel Qualifications
• Monitoring Activities
• Sampling Requirements;
-- Types of sampling activities
-- Types of samples
-- Number and location of samples
- Frequency of testing
-- Data evaluation procedures
-- Data acceptance and rejection criteria
-- Corrective measures sampling plan, if warranted
• Documentation
CQA PLAN
Landfill Components Covered by the CQA Plan
• Foundations
• Liners
• Dikes
• LCRS
• Final Cover
SOIL LINERS CQA
Permeability Testing
• Proposed rule requires construction of a test fill and
field permeability tests.
• Test fill does not preclude use of laboratory permeability
tests.
CQA Report
Documentation includes the following items:
• Summary of all observations, daily
inspection/photo/video logs and reports
• Problem identification/corrective measures report
• Design engineer's acceptance reports (for errors,
inconsistencies)
• Deviations from design and material specifications
(with justifying documentation)
1-23
-------
CQA Report (continued)
• Summary of CQA activities for each landfill component
• Signature of qualified, registered P.E. (or equivalent) in
charge of CQA program. In addition:
-- CQA Officer
-- Owner/Operator
-- Design Engineer.
Review of CQA Reports
By EPA Regional Administrator on selected reports only
SUMMARY OF MINIMUM TECHNOLOGY REGULATIONS
Double Liners and Leachate Collection Systems
> Current Regulations call for FML top liner and
compacted soil bottom liner
• Proposed Rule calls for two design options for the
bottom liner:
1. Composite Liner (FML/3 ft compacted soil)
2. Compacted Soil Liner ( > 3 ft)
1 EPA planning to delete compacted soil bottom liner
option and add option of composite top liner.
SUMMARY OF MINIMUM TECHNOLOGY REGULATIONS
Leak Detection Systems
• Proposed Rule: LCRS between liners to become leak
detection system for landfills (LDCRS).
• Proposed standards for the LDCRS:
-- Minimum bottom slope of 2%
-- Drainage layer hydraulic conductivity of 1 cm/sec and
thickness of 1 ft (for granular materials)
-- Drainage layer hydraulic transmissivity of 5 x 10~4
m2/sec (synthetic materials)
SUMMARY OF REGULATIONS (continued)
• Proposed performance standards for the LDCRS:
- Leak detection sensitivity of 1 gpad
-- Leak detection time of 1 day
1-24
-------
SUMMARY OF MINIMUM TECHNOLOGY GUIDANCE
Final Cover
• Existing guidance calls for multi-layered cap:
-- Vegetative Cover (2 ft)
-- Drainage Layer (1 ft, 10~3 cm/sec)
-- Composite Liner (FML/2 ft compacted soil at 10~7
cm/sec permeability)
• Top slopes should be between 3 and 5%.
• Issue of settlement and waste reinforcement not
addressed in guidance,
• Newer guidance due in October 1988.
SUMMARY OF GUIDANCE AND PROPOSED
REGULATIONS ON CONSTRUCTION QUALITY
ASSURANCE
CQA Program
CQA Plan Submitted by Owner/operator
Implementation of CQA Plan by Independent Third Party
Submission of CQA Report by Owner/operator
Review of Selected CQA Reports by EPA
CQA Plan
Foundations
Liners
Dikes
LCRS
Final Cover
Proposed Requirements for Soil Liners
• Requires test fill for permeability testing.
1-25
-------
SESSION II - LINER DESIGN
David Daniel
and
Gregory Richardson
-------
CLAY LINERS
David Daniels
-------
Clay Liners:
First Part:
- Materials
- Clay Liner vs. Composite Liner
- Darcy's Law, Dispersion, Diffusion
- Hydraulic Conductivity Tests
Laboratory
Field
- Attack by Leachate
Second Part:
- Construction Criteria
- Factors To Be Considered
- Key Construction Criteria
- Excavation and Placement
- Compaction
- Protection
- Quality Assurance
- Test Fill
n-i
-------
Nature of Clay:
1. Definition
A. Grain Size
B. Plasticity
C. Hydraulic Conductivity
2. Composition
3. Importance of Diffuse Double Layer
Grain Size (mm)
ASTM
USDA
Gravel
Sand
Silt
Clay
4.74
(No.4
Sieve)
0.075
(No. 200
Sieve)
None
(Plasticity
Criterion)
0.050
0.002
II-2
-------
A Cloy loam \Silty
30/ — Sandy — \ -^ ---- • -- \ loom
cloy loam
20
loom
Silt loam
Per cent sand
60
H 50
Q.
u
Q 4O
Z
>•
t 30
(J
<
_l
Q.
For classification of fine-grained soils
and fine-grained fraction of coarse-grained
soils.
Equation of A - line
Horizontal at PI-4 to LL=25.5,
then PI = 0.73 (LL-20)
20
MH
10 16 20 30 40 50 60
L IQUID LIMIT (LL)
70
80
90
100
110
II-3
-------
Natural Clay Soils:
0)
-o
c
CD
E
E
o
o
CD
cc
•a
03
i—
'5
cr
a>
CC
Fines Content > 20%
Plasticity Index > 10%
(But High PI a Problem)
Coarse Fragments < 10%
Almost No Particles > 1 in.
-7
["hydraulic Conductivity < 10 cm/s
l_
o
o>
<
E
^o
>-,
'>
o
c
o
o
o
10
-6
10
-7
10
-8
3 10
-9
10
rIO
Upper Bound
'Lower Bound
10 20 30 40 50
Plasticity Index (%)
II-4
60
-------
Blended Soils:
- Sand / Sodium Bentonite
- Sand / Calcium Bentonite
- Sand / Local Clay
- Sand / Other Materials
Amended Soils:
- Clay / Lime
- Clay / Cement
- Clay/Others
4 8 12 16 20 24
Percent Bentonite
-------
Clav Liner
Composite Liner
Leachate
Leachate
FML
A = Area of Entire Area < Area of Entire
Liner Liner
Leachate
Dp.
Leachate
Don't
II-6
-------
Darcv's Law:
Influent
Liquid
L
Soil
q =
q =
k =
rate of flow
hydraulic '
conductivity
H
Vr Effluent
•$%r Liquid
H = head loss
L = length of flow
A = total area
Leachate
Subsoil
H
D
q = kiA
i = Hydraulic Gradient
_ H + D
" D
(Assumes No Suction
Below Soil Liner)
II-7
-------
For a One-Acre Liner:
Hydraulic
Conductivity
(cm/sec)
1 x10-6
1x10-7
1 X10-8
Annual
Leakage
(gallons)
500,000
50,000
5,000
Note: Hydraulic Gradient Assumed to Be 1.5
Advective Transport
Flux
Leachate
Subsoil
i = Hydraulic
H Gradient
H + T
T
(No Suction)
II-8
-------
Leach ate
Subsoil
v = seepage velocity
Li
ru
ne = effective porosity
Time of Travel (TOT)
V,,
Leachate
Subsoil
L Ln,
TOT = 77- =
ki
II-9
-------
Leachate
Effluent
.Concentration
of Solute = c0
Concentration
of Solute = c
0.5
0
No
Dispersion
(torn = ne)
Dispersion
0 1 2
Pore Volumes of Flow
n-io
-------
No Retardation Retardation
0
(n = n
0123
Pore Volumes of Flow
Molecular Diffusion
Leachate
(constant c0)
0
Concentration (c)
u-ii
-------
LABORATORY TESTS FOR
HYDRAULIC CONDUCTIVITY OF
SATURATED SOILS
Important Variables:
• Representativeness of Sample
• Degree of Water Saturation
• Stress Conditions
• Confinement Conditions
• Testing Details
11-12
-------
10~5cm/s
1CT6cm/s
10"7cm/s
10"8cm/s
75ft
30ft
3 Ft
Dyed Water
11-13
-------
Prototype Liner in Houston:
Actual k: 1 x 1CHcm/s
Lab k's:
Location
Sampler k (cm/s)
Lower Lift
3-inTube 4x10-9
Upper Lift
3-inTube 1 x10-9
Lift Interface 3-in Tube 1x10-7
Lower Lift
Block
8x10-5
Upper Lift Block
1x10-8
k
•4— «
o
C
O
O
o
"5
sat
0
0
100
Percent Saturation
11-14
-------
E
o
I x 10
I x 10
-7
40 60 80 100
Backpressure (psi)
-T: 10
E
a
o
3
•a
c
o
o
o
k_
•o
X
-7
-8
-9
(kPa)
50
100
r i
_Sa mple Containing
Desiccation
Cracks
"Sample Containing
No Desiccation
Cracks
10 o 4 8 12 16
Effective Confining Pressure (psi)
-------
Double-Ring Permeameter
Pressure Line
Vent Line
Ring
Inner Effluent Line
Outer
Effluent
Line
Flexible-Wall Permeameter
11-16
-------
Termination Criteria:
1. Equal Inflow and Outflow
2. Hydraulic Conductivity Steady
Status of ASTM Standardization:
• Standard for Flexible-Wall Test
(Water Only) in Final Stages of
Development
• Standard for Fixed-Wall Test
on Hold
11-17
-------
jn Situ Hydraulic Conductivity
Tests for Clay Liners:
1. Borehole Tests:
• Boutwell Permeameter
• Guelph Permeameter
• Other
2. Porous Probes:
• Piezometer
• BAT Device
3. Infiltrometers:
• Air Entry Permeameter
• Single Ring Infiltrometer
• Sealed Double Ring Infiltrometer
Open, Single Ring
Open, Double Ring
Sealed, Single Ring
11-18
Sealed, Double Ring
-------
Sealed Inner Ring
Flexible Bag
Tensiometers
Outer Ring
Primary Issues:
1. Calculation of Hydraulic
Conductivity from Rate of
Infiltration
2. Influence of Overburden Stress
3. Effect of Soil Swelling
4. Termination Criteria / Length
of Test
11-19
-------
Water
Soaked Soil
I = Infiltration Rate
= (Quantity of Flow/Area)/Time
= (Q/A)/t
k = Hydraulic Conductivity
= Q / (i A t) = I / i
Water
|§j^^SE^fflS§S!S
iSoaked Soil"
D
Most Conservative Assumption:
Hp =
11-20
-------
o
o
O
Effective Stress
Swelling Zone
Soil Liner
11-21
-------
>,
>
o
D
o
O
o
"5
Termination of Test
10
-7
Time
Status of ASTM Standardization:
• Existing Standard for Double
Ring Infiltrometer Is Not
Appropriate for Clay Liners
• New Standard for Double Ring
Infiltrometer with Sealed Inner
Ring Is Under Development
11-22
-------
Field Tests:
• A Larger, More Representative
Volume of Soil Is Tested
Laboratory Tests:
• Less Expensive
• Can Saturate the Soil Fully
• Can Vary the Stress
• Can Test with Waste Liquids
Laboratory vs. Field Tests:
• Keele Valley Landfill:
field
Klab
Houston Test Pad:
k.
= 100,000
u
lab
11-23
-------
.Soil-Waste Interactions:
Acids and Bases
- Neutral, Inorganic Compounds
- Neutral, Organic Compounds
- Actual Leachates
Water
pHof
Effluent
7
Hydraulic
Conductivity
Acid
0
10 15
Pore Volumes of Flow
11-24
-------
11-25
03!
O
-------
Flow
Clay
Particle
Double
Layer
Gouv-Chapman Theory:
Thickness
oc
D = Dielectric Constant
n0 = Electrolyte Concentration
v = Cation Valence
11-26
-------
High k Water with Polyvalent
Cations
Tap Water (Note Variation)
Water with Monovalent
Cations
Low k Distilled Water
Water
Organic Chemical
0
1
Pore Volumes of Flow
11-27
-------
Hydraulic Conductivity Not Adversely
Affected If:
1. Solution Contains at Least
50% Water
2. No Separate Phase of Organic
Liquid Is Present
Termination Criteria:
1. Equal Inflow and Outflow
2. Steady Hydraulic Conductivity
3. At Least 2 Pore Volumes of Flow
4. Influent/Effluent Equilibration:
- pH Similar
- Full Breakthrough of Key Ions
- Full Breakthrough of Key Organics
11-28
-------
Stabilization Against Attack:
1. Mechanical
Greater Compaction
Overburden Stress
2. Additives
Lime
Cement
• Sodium Silicate
• Others
10
CLAY STABILIZATION RESEARCH
SOIL: KAOLINITE
STABILIZATION: MODIFIED PROCTOR
ORGANIC CHEMICAL: METH-HEPTANE
Standard Proctor
-2. 00
0. 00
PORE
2.00 4.00 6.
VOLUMES OF FLOW
11-29
8. 00
-------
10
10
-101
CLAY STABILIZATION RESEARCH
SOIL: S1
STABILIZATION: LIME
DRCANTC CHEMICAL: HEPTANE
-2. 00
0.00 2.00 4.00 8.00
PORE VOLUMES Of FLOW
B. oo
10
C/l
o
ie
O 10
O
O
O
o 10
10
| HjO-
-7
,-« ^
,-9 ^
10
.-10
CLAY STABILIZATION RESEARCH
SOIL: S1
STABILIZATION: CEMENT
ORGANIC CHEMICAL: HEPTANE
T
• HEPTANE
T
Unamended
Cement Stabilized
-2.00 0.00 2.00 4.00 6.
PORE VOLUMES OF FLOW
II 30
oo
B. 00
-------
FLEXIBLE MEMBRANE LINERS
Gregory Richardson
11-31
-------
FLEXIBLE MEMBRANE LINERS
SESSION II
EPA SEMINAR
Primary FML
Secondary FML
Native Soil Foundation
(NOT TO SCALE)
Figure 1.2 Synthetic/Composite Double Liner System (EPA, 1985a)
11-32
-------
Mm mum
Thickneit
1
15 cm
3)7 fe cm
# to
-V.V";'.- Solid Waste "-^
Fittn M«dia
o
Hydraulic Conductivity
> 1 X 10-2 cm/iec*
o
aulic Conductivny
) 1 X 10- J c
Hydraulic Conductivity
< 1 X 10-7 em/»«
Unuturated Zone
^^^^
Saturated Zone
ym Saturated Zone WMM&
Primary LCR
• Primary FML
Secondary LCR
•Secondary FML
Clay Liner
Native Soils
Figure 3.1 Profile of MTG Double Liner System
Figure 1.4 Proposed RCRA Cell Cap Profile
11-33
-------
LINER HYDRAULICS
CLAY LINER:
DARCY'S LAW
Q = KIA
SYNTHETIC LINER:
PICK'S FIRST LAW
Q = [ WVT x T ] -APA
FACTORS INFLUENCING
LINER PERFORMANCE
CLAY LINER: HEAD
PERMEABILITY
SYNTHETIC LINER: PENETRATIONS
11-34
-------
Advantage of
COMPOSITE LINER
QCT ~ io Qc
POLYMER TYPES
THERMOPLASTICS - PVC
CRYSTALLINE THERMOPLASTICS
- HOPE, LLDPE
THERMOPLASTIC ELASTOMERS
- CPE, CSPE
ELASTOMERS
- NEOPRENE, EPDM
11-35
-------
Component
Table 1.1 Basic Composition of Polymeric Geomembranea
( after Haxo, 1986 )
Composition of compound type
(parts by weight)
Crosslinked
Polymer or alloy
Oil or plasticizer
Fillers:
Carbon Black
Inorganics
Ant i degr adant a
Crosslinklng system:
Inorganic system
Sulfur system
100
5-40
5-40
5-40
1-2
5-9
5-9
Thermoplastic
100
5-55
5-40
5-40
1-2
Semicrystalline
100
0-10
2-5
_ — —
1
_ — —
_ — •
FIG 4 COMPARISON OF EXOTHERMIC PEAK SHAPES
180°C , 800 psiq
o
UJ
X
28-
24-
20-
16-
12-
8
4
i i r
0 10 20 30 40 50 60 70 80 90 100 110 1ZO
11-36
-------
SHEET PRODUCTION
EXTRUSION - HOPE
CALENDERING - PVC
SPRAYING - URETHANE
TYPICAL MECHANICAL PROPERTIES
HOPE CPE PVC
DENSITY, GM/CM3 >.935 1.3-1.37 1.24-1.3
THERM. 12.5 X 10'5 4 X NT5 3 X 1
-------
Session 54: Tasting
Geosynthetic '87 Conference
New Orleans, USA
TABLE 2. APPROPRIATE OR APPLICABLE TEST METHODS FOR UNEXPOSED POLYMERIC GEOMEMBRANES
Property
Analytical properties
Volati les
Extractables
Ash
Speci f i c gravi ty
Thermal analysis:
Differential scanning
calorimetry (DSC)
Thermogravimetry (TGA)
Physical properties
Thickness total
Coating over fabric
Tensi le properties
Tear resistance
Modulus of elasticity
Hardness
Puncture resistance
Hydrostatic resistance
Seam strength:
In shear
In peel
Ply adhesion
Environmental and
aging effects
Ozone cractcing
Environmental stress-
cracking
Low temperature testing
Tensile properties at
elevated temperature
Dimensional stability
Air-oven aging
Water vapor trans-
mission
Water absorption
Immersion in standard
liquids
Immersion in waste
1 iquids
Soil bun al
Outdoor exposure
Tub test
Mpmbrane
Thermnp las t i c
MTM-ia
MTM-2*
ASTM D297,
Section 34
ASTM 0792, Mtd A
na
yes
ASTH 0638
na
ASTM OR82,
ASTM 0638
ASTM 01004
(mod)
na
ASTM D2240
Duro A or 0
FTMS 101B,
Mtd 2065
na
ASTM 0882,
Mtd A (mod)
ASTM 1)413, Mach
Mtd Type 1 (mod)
na
ASTM 01149
na
ASTM D1790
ASTM 0638 (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM £96, Mtd BW
ASTM 0570
ASTM 0471, 0543
EPA 9090
ASTM 03083
ASTM 04364
b
Liner Without Fabric
Crosslinks
MTM-1<»
MTM-2a
ASTM 0297,
Section 34
ASTM 0297,
Section 15
na
yes
ASTM 0412
na
ASTM 0412
ASTM 0624, Die C
na
ASTM 02240
Ouro A or 0
FTMS 1018,
Mtd 2065
na
ASTM D882,
Mtd A (mod)
ASTM 0413, Mach
Mtd Type 1 (mod)
na
ASTH D1149
na
ASTM 0746
ASTM D412 (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM E96, Mtd BW
ASTH 0471
ASTH 0471
EPA 9090
ASTM 03083
ASTM 04364
b
Rei nf orcement
Semi cryst a Mine
MTH-H
MTM-23
ASTM D297,
Section 34
ASTM 0792, Mtd A
yes
yes
ASTM 0638
na
ASTM 0638 (mod)
ASTM 01004
ASTM 0882, Mtd A
ASTM 02240
Duro A or 0
FTMS 1018,
rttd 2065
ASTM 0751. Mtd A
ASTM D882,
Mtd A (mod)
ASTM 0413, Mach
Mtd Type 1 (mod)
na
na
ASTM H1693
ASTM 01790
ASTM D746
ASTM 0638 (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM E96, Mtd BW
ASTM 0570
ASTM 0543
EPA 9090
ASTM D3083
ASTM 04364
b
Fabric reinforced
MTM-ia
(on selvage and
reinforced sneeting)
(on selvage and rein-
forced sheeting)
ASTM D297,
Section 34
(on selvage)
ASTM D792, Mtd A
(on selvage)
na
yes
ASTM 0751, Section 6
Optical Method
ASTM 0751, Mtd A and B
(ASTM 0638 on selvage)
ASTM 0751, Tongue Mtd
(nodi f i ed )
na
ASTM 02240
Duro A or D
(selvage only)
FTMS 101B,
Mtd 2U31 and 2065
ASTM 0751, Mtd A
ASTM 0751,
Mtd A (mod)
ASTM 0413, Mach
Mtd Type 1 (mod)
ASTM 0413, Mach
Mtd Type 1
ASTM 0751, Sections 39-42
ASTM 01149
na
ASTM D2136
ASTM 0751 Mtd B (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM E96, Mtd BW
ASTM 0570
ASTM 0471, 05-13
EPA 9090
ASTM 03083
ASTM D4364
b
"^e Deference (8).
''See reference (I2J.
"a « Not aoplicable.
11-38
-------
4000
3000
HOPE (Biaxial)
2000
1000
f- /^ PVCXBiaxial)
CPE (Biaxial)
100
200
(KEORNER,RICHARDSON-UNI AXIAL)
(STEFFEN-BIAXIAL)
TO 3860 PSI AT 1180%
300
400
500
STRAIN, %
Figure 6.3 FML Stress-Strain Performance
11-39
-------
FML DESIGN ELEMENTS
MINIMUM TECHNOLOGY GUIDANCE
STRESS CONSIDERATIONS
STRUCTURAL DETAILS
FABRICATION
MINIMUM TECHNOLOGY GUIDANCE
30 MIL THICK FML
45 MIL FML WITH EXPOSURE
DE MINIMIS LEAKAGE
11-40
-------
STRESS CONSIDERATIONS
SELF WEIGHT
COMPOSITE PRIMARY
WASTE SETTLEMEHT
LOCALIZED SETTLEMENT
NORMAL COMPRESSION
SIDESLOPE
BOTTOM
SELF WEIGHT
w
JSION = W
- F
11-41
-------
Cell Component: FLEXI&LE. ME.ME.RAJJE
Consideration: irM*'LE
j EVALUATE
ASlLlTY of FML -ro ^uPPo«T IT-S Ok-JU ^-Itl^HT ow TH£
Required Material Properties
• FML -TO- ice ^ 1>L
FML THKCU.U £•»•-, ,-L
FML
Drill MIC MIMTUH
Range
0 .12- T. 1 .4
lo"T. 46"
JO To 120 HIL
Test
DIRECT
"TeusiLE
Standard
A-sTH Dfcifl
Analysis Procedure:
FML
UH£»E
pML ffeusiue Srnes-s^ G*
G'-T/A-
FML X.
1 - t
Design Ratio:
References:
Example:
C\ v t u '.
• 60 M.I- MOPE.
• FML 5ct<:iFi<;
(Is)
FML TtuiiLt Fo
U)=
.4« TiT ]=C
- 7<7-5 Ib/fT
G" - 13.0/1" i
i'J Lft.00e*.re.BY FML YltLC?
ib/
f=T«
18-0
20
pe. .
[Example No. 5.1
-------
WASTE SETTLEMENT
TENSION =
20
15
10
i-n
o
15'
I I
Circular Trough Model
Triangular
^
u i•- "Mri nn i
(Knipschield,1985)
0 0.1 0.2 0.3
SETTLEMENT RATIO, S/2L
Figure 3.4 Settlement Trough Models
11-43
-------
Cover Soil °cs
jTrrnrFrrTTITTTr
cs
HORIZONTAL ANCHOR
•V ANCHOR
^ Tcosp /Xcover Soil Ks
4 ^TlTT:2^TnTrT"T
Tsin i
CONCRETE ANCHOR
Figure 3.10 Forces and Variables - Anchor Analysis
11-44
-------
Cell Component: FLEXIBLE Mt
Consideration: FML
FML PLACED IU VAPJ i
Y p°a.
-------
Figure 4.1 Geometry of Typical Ramp
18' Typical
FML-
FML-
Figure 4.2 Cross-Section of Typical Access Ramp
11-46
-------
RAMP DESIGN CONSIDERATIONS
SLIDING DUE TO TRAFFIC
ROADWAY
• DRAINAGE
SLIDING DUE TO TRAFFIC
u
11-47
-------
Cell Component: RA.MP
STABLE
F~i T
LOAD.
RAMP -SJB-6A-SE. ' •=>
Required Material Properties
SO.L. -
Dull MIC Miramun
Range
14 - ti'
Test
Standard
Analysis Procedure:
(?E-si*Tiuq
Design Ratio:
P^w.u' 3-0 1-"™
2.. (9 VJ'T
References:
Example:
= 56 T»
31
l»*
-------
ROADWAY
DRAINAGE
.s
CJ- ^
UMtRg. IMCH
11-49
-------
I
Ln
o
Cell Component :
Consideration: NME£L
THAT
F"ML.
Required Material Properties
FML
Drill MIC Mnnun
A
Range
2.6 - mo-
f Ri
Standard
Analysis Procedure:
(O DeF'Mg FIE.LO ^
PR --
(J-.
Design Ratio:
References:
Example:
- 55
2,' .
(,-5
= "7- "7
Example No. 4. 5
-------
Cell Component:
Consideration :
.' VERIFY-THAT
Required Material Properties
Pm.MeA6iL'r»,K j
Dull M1G Miiwiun
Range
-t -
10- (O £»
Test
Standard
Analysis Procedure:
X1 Rw
of Leg
& i
Design Ratio:
References:
Example:
KM £
t 3.1
o - .
X" RA.i_irALL' 3 lU
FLQUJ RATE.
56 I Ul
-s
CALCULATE Pe-i.qu g A^ O
I.Z.
i
-------
STANDPIPE DESIGN
CONSIDERATIONS
DOWNDRAG FORCES
PUNCTURE OF FML
FML
Figure 4.5 Standpipe/Drain - Details
11-52
-------
Cell Component:
Consideration '
Am potv.-1-n.M. DO^
c"oMf*.Re £»A.nM<^i FOB.
Required Material Properties
F,LL
Drill MIC Mmmum
Range
Test
Standard
Analysis Procedure:
(0
nU
Tin
1»*HJi
**Q
LJCXMH
Kill
COMUfTLHCf
0* ««.
Vt*T MT
VX»
utO «i/»
vtirf in"
*urr vy I
WT
HCO 111"
Kt*»
vtWf il^»
OXlJtm.C
0 • JVC
JXI • WO
MO • -000
«W • KH,C4
o • lio
/JO • **0
**o • rig
tw • »»
1)0 • iVX)
0 • JXl
IX) • **0
MO • no
no • no
TO • HO
(?ePU<=Ti"M
6?
Design Ratio:
References:
Example:
STAXIDPIP&
- Boo ?-!f
o.ss
SSS°°°
555
°12.5
\
AVER
AU
,VEHT
\T
i
\
1
/C£ OJff
L PILES
t
SOFTf
rWO)K
\ 4 _
I
s
%,
-AVEWA
\.
M STIFF
STIFT
n*rio OF
CA/C
SECURV1
rre PILE
~— —
VEBT
.ran
TIFF
KX» 15OO 300O 2500 30OO
OOMESIOH C.PSF
Example No.
-------
1.0
c
o
u
2.0
edge
1.0
r/a
1 r
1 T
A) ELASTIC SETTLEMENT CONSTANT
Clay Subgrade
Sand Subgrade
Elastic Subgrade
(after Terzaghi and Peck)
8) DISTRIBUTION OF CONTACT PRESSURES
t= u
'
1
/
t
\
A* "W'T
Method 1 Method 2
C) CALCULATION OF FML STRAIN
Figure 4.7 Standpipe Induced Strain in FML
11-54
-------
Cell Component: STA.MDP.PE
rrrxna:/-!^^!:.,....!- PICTURE or FML -. VtciF-f TVIKT POWJU-P
uonsicieratiOM.
SEITLEMCWT <9I* 'ST^.'ODPiPE UJILL kJoT £TAU
OF UgptRLviu^ LCR.
Required Material Properties Range Test
£TLAY SJft<^«»,Df.
• £eMP*£**l*M TMCEV , Cc £o .^> f.^JIOUOATiovJ
FML (?EXATED*.
• FML/SO.C F»i6TM>u Aw^Lt, S io-ro° p,»e<;r 5wt»n
•FML STWA.M- AT-Y'ttD |o- iflTo
Dull M1G Mnnuti
Analysis Procedure:
"rvr,LjTED
Standard
ASTM 2435
P* A.vS*>- OF JuDtP-l-^iw*;
. > A f ^ -j| ^\>3 l^'Ti^L VOID ftA.Tlo oF C.
^•u "1 X M c'o 1 &£*<-/« » 1 .6. 5's.ip^'
^ E*TiM^T£ STRAILJ- MtTMoc 2. CPiS^'Tc)
DC, ^ ^
LA-C
X
H-M
T-^S jCT///r
f
Design Ratio: References:
iTAMori^e
Example: |^(r r
= n " - ! 1
•StkUDpiPfc PER EXAMPLE. T .^ UM.TC"' L^""' 46*
*i~'-*;^ Stje^nAE^ ii^g^pcp ir^r^1^
. J^^^\:L^ ,T „,. ^- IT^ , I
CO C^JKTt ELA^C SETTLEMEuT ^^Po^MT A
3.ZTO--35-) , P'q>-5/^,^-3.r7«F
A a 1 iO Ao ' '^ — * * ^^ 1 LJCH E ~ boO t 1.8 K SF *• i i"»Jtx> i/^F
(£.)c^L6UcAv"TE ^kJt*LiD
-------
Geotextile
FML
Weld
RIGID 'PENETRATIONS
Geotextile
FML
steel clamp
pipe sleeve
Weld
FLEXIBLE PENETRATIONS
Primary FML
Weld
'Pipe
Secondary FML
Figure 6.4 Rigid-Flexible Penetrations - Details
-------
FML PANEL LAYOUT
• FIELD SEAMS SHOULD RUN UP-AND-DOWN
SLOPE, NOT HORIZONTAL
• MINIMIZE FIELD SEAM LENGTH
NO PENETRATION OF PRIMARY
FML BELOW TOP-OF-WASTE
K @
© \
©
©
©
x"®
^
x
i
@ © i © ® ® ©
i
/C.J 1 L J j 1
©
©
r T ~i T~ T
i
I
1
K
r, ~^
© /
/ ®
©
©
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9\
&
A
A
A
£2A
t2\
K
O PANEL NUMBER
A SEAM NUMBER
Figure 6.1 Panel-Seam Identification Scheme
11-57
-------
SURFACE IMPOUNDMENT CONSIDERATIONS
LONGTERM EXPOSURE OF FML
"TEMPORARY" NATURE OF SI
POTENTIAL FOR GAS IN LCR
FREQUENTLY CONTAIN LIQUIDS
Place Vent Higher than Maximum Liquid Level
at Over-Flow Conditions
— Two-Inch Minimum
Drainage Composite
Openings in Vent to be Higher than
"Top of Berm or Overflow Liquid Level
Liner.
Air/Gas Vent Assembly
—Appro*. Six-Inches
Wind Cowl Detai
Concrete
Bond Skirt of Vent to Liner
Gas Flow
Figure 3.12 Typical Gas Vent Details
11-58
-------
Cell Component: FLEXIBLE MEMBBA.ME LIUIUC,
-i|ir- 2,73^
-173 6,
&UT
BE
1 -O
L-* KjoT •STBEiSED
Example No. 3.16
-------
PANEL ANCHORING
FORCES ACTING ON PANEL
- SELF WEIGHT
- WIND
ANCHOR WITH SAND BAGS
ANCHOR TRENCH FILLED AFTER SEAMING
11-60
-------
Table 6.2 Wind Uplift Forces, PSF (Factory Mutual System.'
Height Above
Ground, (ft)
0-15
30
50
75
Wind Isotach, mph
City .Suburban Areaa,
and Wooded Vreas
70 80 90 100
10"
10
12
14
11
13
15
18
14
17
19
22
17
21
24
27
Towns
110
20
25
29
33
(Figure
6.2)
Flat, Open Country,
Coastal Belt>1500ft
70 80 90 100
14
16
18
20
18
21
24
26
23
27
30
33
29
33
37
40
or Open
from Coast
110 120
35
40
44
49
41
4S
53
58
Uplift Pressures in PSF
(FACTORY MUTUAL SYSTEM)
Figure 6.2 Design Maximum Wind Speeds
11-61
-------
Cell Component : Fi-t*i&<.t ME.M&OAUJE.
Pj^n^irlnr^if inn • Uliup LIFT: £TA.LciiLAJt THt. «E.ffl«Ji^E.D «
LXinsiueration . • ,-.. rr- ,
SPA^I«-"I FOR F^L/FM^. PAKJEL^ DJmu^
Required Material Properties Range Test
Dull M1G Miramun
Analysis Procedure:
('^ DtTeRMiu£ DE*'<;H M*X-IMJH UIMO SPEED V^.
•Use «iT6 SPE^iF'C PATA <^ REF£ftELJ<:;£ Fic^&.Z.
KfcF"£B.£M<^£ lAfrtfc 6.2. W/ V^.MO :p*' P UD
KJoTt " r tflF^^M LiKjeAJi. INJTCf* P^L^Tt-oKJ F*?R PtPTH^ <
(3; ^- AL-4^ dLAT'6 SA.KJQ 3*.^ ^pAk^iwq
• TP.I&UTARY A.R6A,3 Pu,uo/uJi- TA
(4) ^AicJi-AnE DE.IIC.U RATIO
nc TA/r 1
L^r~, — • / Lx'pJAi- FIELD TmBiiTA^y AAt*>J
^L^lMT.
Standard
A5TMDT,.
o FT
Design Ratio: References:
DCM, 'I.I (SM.*T-Ti«"! <^0 F*-^"»^MuT''A'- 'S-^rtM
Example:
• PHILADELPHIA ( PA
• FMLDE.PTH -~z o -*.->io FT
• HEIGHT TO FM • -2oFT OFT -*2oFr
01 PETERMIME DESICLJ MAxiMJi-i UIMO Sec.tot VUIUD
VLlllJD-_8o MPH CReF F^i.z")
(l") DtTERMiME UI'MD LJp-LiFT Pftee-SOaE. R.,llJD
^ — Tw-rt«f«.^T-i-j
^ ^_ ^R£f: TA.6LE.ii.2-)
^^^ 1
1
1
i
..I i
-1.0 -AO -Zo 0 2o 40 to ,0 HEIGHT FT
Dep-iM -2o FT =*• II P5r
° FT •*- 14 Pip
-20 Fr •*" 80|b/|| PlF- 7^5 p-r
-2oFT. =*• ~I.~5/\o.o- o T3 MC
o FT =^ 5-T/io.o = O.57 |JC
Example No. 6?.l
-------
SESSION III - COLLECTOR DESIGN
Robert Koerner
-------
SESSION III - COLLECTOR DESIGN
(by R. M. Koerner)
1.0 Overview
1.1 Types and Purpose
1.2 Drainage Materials
1.3 Filtration Materials
1.4 Design-by-Function Concepts
1.5 Test Methods and Standards
2.0 Leachate Collection System
2.1 Overview
2.2 Granular Soil Drainage Design
2.3 Perforated Collector Pipe Design
2.4 Geonet Drainage Design
2.5 Granular Soil Filter Design
2.6 Geotextile Filter Design
3.0 Leachate Removal System
4.0 Leak Detection Collection Systems
4.1 Granular Drainage Design
4.2 Geonet Drainage Design (between two FML's)
4.3 Composite Primary Liner Considerations (between Gt/clay
primary and FML secondary)
4.4 Response Time
5.0 Leak Detection Removal System
5.1 General Comments
5.2 Sidewall Monitoring
5.3 Gravity Monitoring
6.0 Surface Water Collector System
6.1 Design Quantity
6.2 Types of Drainage Systems
7.0 Closure Gas Collector and Removal System
7.1 Overview and Quantities
7.2 Design of System
7.3 Collector and Vent Details
ni-i
-------
1.0 Overview
1.1 Landfill Collector Systems
1.
2.
3.
Type
leachate
collection
leak
detection
surface water
collection
Location
directly below waste
and above primary
liner
between primary and
secondary liners
above liner system
in cap/closure above
landfill
Fluid Collected
leachate
(large quantity)
leachate
(small quantity)
water
(intermediate
quantity)
Purpose
collect and
remove/treat
leachate
determine if
primary liner leaks
and to what degree
redirect water off
of cover
Anchor Trench
nch
III-2
-------
1.2 Materials used for Leachate Collection Systems
(a) the Drainage Part
Type
Advantages
Disadvantages
pipe
soil (gravel)
geonet
geocomposite
common usage
common design
rapid transmission
common usage
common design
durable
saves vertical space
rapid transmission
not likely clogged
saves vertical space
rapid transmission
not likely clogged
takes vertical space
particulate clogging
biological clogging
creep
takes vertical space
slow transmission
particulate clogging
biological clogging
needs filter soil
moves under load
intrusion
creep
needs geotextile filter
new technology
intrusion
creep
needs geotextile filter
very new technology
III-3
-------
1.3 Materials Used for Leachate Collection Systems
(b) the Filtration part
Type Advantages Disadvantages
soil (sand) common usage takes vertical space
common design paniculate clogging
biological clogging
moves under load
geotextile saves vertical space particulate clogging
easy placement biological clogging
doesn't move installation survivability
new technology
III-4
-------
1.4 Design-by-Function Concepts
(a) For Drainage
DR = qallow/Qreqd
or DR = ea,|OW/ereqd
where
DR = design ratio
q = flow rate per unit width
0 = transmissivity
(b) For filtration
DR = qallow/qreqd
or DR = Vallow/Vreqd
where
DR = design ratio
q = flow rate per unit area (or flux)
\j/ = permittivity
III-5
-------
Definition of Hydraulic Terms
(a) In-Plane Flow
(w x t)
q = k i A
= k
^ = (kt)
w
if 6 = k t
— = 9 (')
w
where
— = flow rate per unit width
w
0 = transmissivity
note that when i = 1.0; (q/w) = 6
otherwise it is not!
(b) Cross-Plane Flow
q =
= k
k i A
Ah
t
q =
Ah A
V = T =
AhA
where
\l/ = permittivity
q/A = flow rate per unit area ("flux")
III-6
-------
1.5 Test Methods and Standards
ASTM Test
Designation
Used to Determine
Material
Value Used For
D2434 Permeability
D2416 Strength
F405, F667 General Spec.
D4716 Transmlssivlty
D4491 Permittivity
D4751 Apparent Opening Size
CW-02215* Gradient Ratio
GRI-GT1** Long Term Flow
Soil
Underdrain Pipe
HOPE Pipe
Geonet, Geocomposite
Geotextile
Geotextile
Geotextile
Geotextile
LCS, LDCS
LCS, LDCS
LCS, LDCS
LCS, LDCS
LCS filter
LCS filter
LCS filter
LCS filter
•Corps of Engineers Test Method
"Geosynthetic Research Institute Test Method
III-7
-------
2.0 Leachate Collection System
2.1 Overview
• Location is above primary liner directly accepting leachate
from waste
• 1985 MTG Regs require:
• 30 cm (12") thick
• 0.01 cm/sec (0.02 ft/min)
• > 2% slope
• includes perforated pipe
• includes filter soil above it
• must cover bottom and sidewalls
• Many recent designs use geonet for sidewalls, tying into
granular drain at bottom
• Geonet must use geotextile as a filter
• The geotextile often extends over the granular drainage layer
at bottom
III-8
-------
2.2 Granular Soil Drainage Design
(a) Based on MTG values
q = k i A
= (0.02) (0.02) (1 x 1)
= 4 x 10"4 ft3/min
(b) Based on Mound Model (ref. Richardson et al. 1987)
INFLOW
I I i I I I till
DRAINAGE LAYER
L/C
max
2
tan a
.
+ 1
tan a
tan a + c
where
c
k
q
q/k
permeability
inflow rate
Using a maxium allowable head (hmax) of 12", the above equations are
usually solved for the underdrain pipe spacings as the unknown, i.e., "L".
The major variable being the inflow rate which is solved by a "water
balance method".
III-9
-------
Water Balance Method
PERC = P - R/O - ST - AET
where,
PERC = Percolation, i.e. the liquid that permeates the solid
waste (gal/acre/day).
P = Precipitation for which the mean monthly values are
typically used.
R/O = Surface run-off
ST = Soil moisture storage, i.e., moisture retained in the
soil after a given amount of accumulated potential
water loss or gain has occurred
AET = Actual evapotranspiration, i.e. actual amount of
water loss during a given month
Notes
Range of Percolation Rates in USA is
15-36 inches/year, after TRD, 1988
(=1100 to 2700 gal/acre-day)
Computer Model "HELP" - Hydrologic
Evaluation of Landfill Performance, after
Schroeder, et al. 1984
111-10
-------
2.3 Perforated Collection Pipe Design
(a) With known percolation and pipe spacing,
obtain required flow (see Figure 3.1)
(b) Using the required flow and the maximum slope
obtain the required pipe size (see Figure 3.2)
(c) Check the pipe strength and obtain its
deflection (see Figure 3.3) to see if tolerable
in-ii
-------
120
£ 100
6
O
o
O
80
60-
40-
20-
T
4
Percolation, in inche* per month
Where b= width of area contributing
to laachate collection pipe
Figure 3.1 - Required Capacity of Leachate Collection Pipe, after
TRD, 1983
111-12
-------
i
t-1
CO
rrnyt^ ;r;''"
i- 41. *_PIi, 11:1:1.
PIPE- FLOWING FULL
BASED ON MANNING'S EQUATION n = o.oio
50
03 04 0.5 0607060910
20 30 40 506070808010
Slope of pipe in leet per thousand feet
Figure 3.2 - Sizing of Leachate Collection Pipe (Plastic Pipe Institute, 1985), after TRD, 1983
-------
LU
DC
D
CO
CO
LU
QC
CL
DC
LU
12,000
10,000
8,000
~ 6,000
CO
9 4,000
95%
, SOIL
/ DENSITY
2,000 y~^
INITIAL EFFECT OF
RING STIFFNESS
75% SOIL DENSITY
PLOT OF VERTICAL
SOIL STRAINS
0 5 10 15 20 25
RING DEFLECTION. A Y/D(%) = € EXCEPT AS NOTED
Figure 3.3(a) - Vertical Ring Deflection vs Vertical Soil Pressure for
18-inch Corrugated Polyethylene Pipe in High Pressure
Soil Cell. Silty Sand Backfill with Gravel (3/8" -
1/2") Envelope.
10 r^
LU
oc
D
CO
CO
LU
DC
a.
O
co
<
O
H
DC
LU
>
5 10 15 20
RING DEFLECTION , A Y/D (%)
Figure 3.3(b) - The EFfect of B/D on Ring Deflection —(Not Significant
in Loose Soil for B/D^ 2), after ADS, 1988
111-14
-------
2.4 Geonet Drainage Design
• types available are listed in Table 3.1
• they must be chemically compatible with leachate
• they must support the entire weight of the landfill
• the allowable flow rate or transmissivity is evaluated
by ASTM D4716, see data of Figure 3.4
• this value is compared to the required (or design)
flow rate or transmissivity
111-15
-------
Table 3.1 - Types and Physical Properties of Geonels (all are polyethylene)
Manufacturer/Agent
Carthage Mills
Conwed Plastics
Fluid Systems Inc.
• Tex-Net (TN)
• Poly-Net (PN)
Geo-synthetics
Gundle
Low Brothers
Tenax
Tensar
Product Name
FX-2000 Geo-Net
FX-2500 Geo-Net
FX-3000 Geo-Net
XB8110
XB8210
XB8310
XB8410
XB8315CN
TN-1001
TN-3001
TN^OOl
TN-3001CN
PN-1000
PN-2000
PN-3000
PN-4000
GSI Net 100
GSI Net 200
GSI Net 300
GundnetXL-1
GundnctXL-3
LotrakS
Lotrak 30
Lotrak 70
CE 1
CE2
CE3
CE600
DN1-NS1100
DN3-NS1300
-NS1400
Structure
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
foamed, and extruded ribs
extruded ribs
extruded ribs
foamed, and extruded ribs
foamed, and extruded ribs
extruded ribs
exlruded ribs
extruded ribs
extruded ribs
exlruded mesh
extruded mesh
extruded mesh
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
extruded ribs
Roll Size width/length
ft.
7.5/300
7.5/300
7.5/220
6.9/300
6.9/300
6.9/300
6.9/220
6.9/300
7.5/300
7.5/300
7.5/300
7.5/300
6.75/300
6.75/300
6.75/300
6.75/300
-
6.2/100
6.2/100
6.6/164
6.6/164
6.6/164
4.8/66
7.4/82
7.4/82
5.5/100
5.2/98
6.2/98
6.2/98
m.
2.3/91
2.3/91
2.3/67
2.1/91
2.1/91
2.1/91
2.1/67
2.1/91
2.3/91
2.3/91
2.3/91
2.3/91
2.0/91
2.0/91
2.0/91
2.0/91
-
1.9/30
1.9/30
2.0/50
2.0/50
2.0/50
1.5/20
3.8/25
2.2/25
1.67/30.5
1.6/30
1.9/30
1.9/30
Thickness
mils
200
250
300
250
160
200
300
200
250
200
300
200
250
160
200
300
250
160
200
250
200
120
200
290
250
200
160
160
220
150
200
mm
5.1
6.3
7.6
6.3
4.1
5.1
7.6
5.1
6.3
5.1
7.6
5.1
6.3
4.1
5.1
7.6
6.3
4.1
5.1
6.3
5.1
3.0
5.2
7.3
6.3
5.1
4.1
4.1
5.6
3.8
5.1
Approx. Aperture Si/e
in.
0.3 x 0.3
0.35 x 0.35
0.3 x 0.4
0.25 x 0.25
0.3 x 0.3
0.3 x 0.3
0.3 x 0.4
0.35 x 0.35
0.25 x 0.25
0.3 x 0.3
0.3 x 0.3
0.3 x 0.3
1.2 x 1.2
2.8 x 2.8
0.3 x 0.25
0.3 x 0.35
0.3 x 0.25
0.3 x 0.25
0.3 x 0.3
0.3 x 0.3
0.3 x 0.3
mm
8x8
9x9
8x 10
6x6
8x8
8x8
9x9
8x 10
6x6
8x8
8x8
8x9
30x27
70x70
8x6
9x9
8x6
8x6
8x8
8x8
8x8
-------
cr
s
5IJUI
I5UKJ
Normal SIIL-SS (IbS'sq. h)
riDPE-Polynei-HDPE
Normal Siress (JDS/sq h)
HDPE-Poiynei-200 mil GT-Kaolnme Clay
Figure 3.4 - Flow Rate Curves for a 250 mil Geonet
111-17
-------
Various design methods for required flow rate or transmissivity
(a) Geonet must be equivalent to MTG Regs for natural materials
9 > 0.02 ft3/min-ft
(b) based on estimated leachate inflow (Richardson, et al. 1987),
4hmax + 2L Sin
(see example following)
(c) based on surface water inflow
Q =CI A (EPA, 1986)
where
Q = surface water inflow
C = runoff coefficient
I = average runoff intensity
A = surface area
(see example following)
111-18
-------
M
13
co
DO
Cell Component:
Consideration:
VEOIFY T-HAT
Required Material Properties
Dull MIC
Range
~
Test
Standard
Analysis Procedure:
'
io
"5
MAXIMUM MC*.'-I*.L
' PAT*.
k^ - | Fo«T pf HtAP
P'FiUA-L DEPTH CAP r«
^S "UuiT" UJtlC|HT "f TlLl-
FltLD Cj"pADi£ KlTj L
p .1*
Design Ratio:
References:
WONIC (I^
ic.HA.fecH
Example:
MT P ' IZo1
DOIT Ulr.
LtACHATC (wFLow BATC, a, o-o\rt\ovr
L*.t>oCi^-\0f,-( TctAKJiMiy>ivirt' DATA
PeFiuE MIUIMJM
T=
* O'OI
: 1 1 "•!
- ££V----.*::::.T.-.---
";--- 7
: i
: t~~A A a. — t
1 1 1 L __
1 ' ' ;
:
3 0
* ;
i £ '-
i
HCXMAI JTIliS ,
O 100
• iOOO
O 1COO
• 10000
Ji -10 .M 1 00 1 11
HYDtAUlIC f.l AIHINI
.000 M
Example No. 3
-------
Cell Component:
Consideration:TgAU»Hi**i^ iT"x : <2PERA,-noMt> , VEO.IFYTH*T
L-dK WIU_ HAkJDLt :SLj«FA*l!
of THE FACILITY
Required Material Properties
PLAWAC
Dull MIC
Range
1° 1-1*
Test
Standard
Analysis Procedure:
(l") C AL^ JLAtE I?UKJ»FF VoLUME
M
•a
1
w
CO
ME T»
L<::R
q
kJl-lEA,E L » FL^UI LEkJcfH
A l-i > HtA,(7 Lo^-i
UJ »• wjipTH or LcB.
PR'
Design Ratio:
TH*-T fHt
SvSvjT UIILL
References:
Example:
AK.ie.rr
(20
(4)
Rj UOFF VOL Jr-tt
* 2-5 -
e-9uip.£D
AT
p -
-"IT
Example No. 3.2L-
-------
2.5 Granular Soil Filter Design
(a) Design is based on particle size curves
|00
is*
(b) Adequate Flow
(3to5)d15
d.s.
(c) Adequate Retention
d < (3to5)d
15f
(c) Clogging
(by experience)
111-21
-------
2.6 Geotextile Filter Design
(a) Adequate permittivity (see example following)
where
= Permittivity from ASTM Test D4491
maxj
- = inflow rate per unit area
h =12"
max
(b) Retention of particulates in leachate (see example following)
095 < fct. (d50- cu' DR)
where
095 = 95% opening size of geotextile (Corps of Engineers
CW02215)
d50 = 50% finer of sediment in leachate
CU = d6o/d10
DR = relative density
(c) Clogging Potential (see example following)
• Gradient Ratio Test - Corps of Engineers CW 02215
• Long Term Flow Test - Geosynthetic Research Institute
GT-1
111-22
-------
M
"0
Cell Component: LBA^MATE Cou.ef.r-,ofj/R
t~,<~*j-
Consideration: E&p^UH^LDl, VERIFY THAT *
WILL ALLOW
LEAC.HATE 1* FLOW
If.
Required Material Properties
Drill MIC M»«nm
Range
Analysis Procedure:
(ft ^AUJLATt" K t<*a.*tp
HEAD
Design Ratio*.
DR •>
Test
Standard
HEAD
A-*vR.EA of Tt-ST
References:
Example:
0s)
L^ |-le*0 • 1 Pf ( Mri:i
REQUIRED
^fc^fcxTiLE.
8*>
I Cjto~
AAfcA
HE.AD,MM
- H ... -» .
Example No.
-------
Cell Component i
Cou.e\
f\. • it o\
X
\
g
EVALJA.TE fn-re.t3.
.25
2.00
2.7.7
Example No.
-------
H
H
ro
Cell Component: LEACHATE ^oLLe^Tkx-i/^EMovxL
Consideration: FILTER-'
p', EVW.JA.TC THE
t^ OM -THE
of
if A.
Required Material Properties
Dull MIC Miiwrun
Range
Test
Standard
Analysis Procedure:
•M CJRAPI6MT R*.TIoTE6T
lfc»S:
-LAV,,-,
T <1.'FLOM BATt
"-oq -Tt a M FI«UJ "Tt sT
--ra»."»iT.oM TIME.
= 5uJ«c;»,Ti^e ^")
» 4r«<»j-;iy utifxT'** ^ MI
TIME
Design Ratio:
References:
Example:
euT RA.TI
5-77 Zo
'
I.Z4
. '^ttge-.Tii-C MA.Y ^J^f eg.
-------
3.0 Leachate Removal System
FML
FML
FML
Figure 3.5 - Various Sump Details
III-26
-------
4.0 Leak Detection Collection System
4.1 Granular Drainage Design
• select design (required) quantity for leachate leakage
through primimary liner
• take required thickness
• calculate flow rate design ratio
(direct use of Darcy's Law)
• add required pipe network
111-27
-------
4.2 Geonet Between Primary and Secondary FML's
• select design (required) quantity for leachate leakage
through primary liner
• determine laboratory flow rate of candidate geonet
• reduce this value to conform to site specific conditions
• determine flow rate design ratio
(direct use of Darcy's Law)
• no pipe network required
111-28
-------
4.3 Geonet Beneath Geotextile/Clay Primary
design quantity same as before
allowable flow rate of geonet reduced due to
• geotextile intrusion
• geotextile creep
calculations same as before
111-29
-------
4.4 Response Time
calculations based on velocity in geonet and/or
granular soil drainage layer
uses Darcy's Law
must use "true" velocity in granular soil
design example follows
111-30
-------
Cell Component:
SY-STE
M
Consideration: 1^±^^±i^lr_
LAIC THLMIMIMUM!
To BE
THE
Required Material Properties
LCC. p0A.i«jASe
-5ip«^».LL
LCE.
, HfDtUa
D'llt MIG Mrarun
Range
.-> n
Test
UOklE.
Standard
Analysis Procedure:
i)£*J.C.. ~[*llf. flo>J Vtf^i r< IM^TKITHtTk: L£P
T
K]
1 J »AUO
Design Ratio:
References:
j-t^r»a P»rt -j
Example:
filYm-.
• r^go4|-r>f ' <5.S
5j-kl|-> fe^TTOM L^g.
20 FT.
t' .00 \/ -5
(t~) tT»,L<:Juk.Tt 'Taue'
«po' f ,
110
T^
.88 mo"
,(^^2580
Example No. 3l
-------
5.0 Leak Detection Removal System
5.1 General Comments
• requires monitoring, sampling and removal of leachate
• during construction it takes surface water thereafter
leakage through primary liner
• vertical standpipes are passe
• usual method is up sidewall between primary and
secondary liners
111-32
-------
5.2 Sidewall Monitoring
• typically 6" or 10" HOPE pipe
• bottom in sump collection area
• top penetrates through primary liner
(requires "boot" and excellent seal)
• numerous choices of monitoring and retrieval pumps
• depends on quantity (difficult decision)
• see Figure 3.6
111-33
-------
'WASTE
PlQlliC Pipe
=* 100 mm 14.0")
Primary GM
Secondary CM
Submersible Pump
ilhin Pipe
Primary LCR
Side Slope
Figure 3.6 - Leak Detection Removal Details
111-34
-------
5.3 Gravity Monitoring
• requires penetration of secondary composite liner
(both FML and clay)
• requires manhole on opposite side of landfill cell
• see Figure 3.7
111-35
-------
SECONDARY LCR MONITOR
(a) Secondary LCR Monitor - Above Grade Cell, after Richardson, et al
1987
. WANMOLC rKAUC »ND
• ITM VFNTED LID
FldllM CKADt TO iLO"L
AWAT FROM MAMMOLC.
DISCH4XGE. LINE FHOtl LEAK :
COLLtCTlON/DCTECTIOM STSTEM
(SOLID WAU.-6" DIA. O1 LARGER)
-^
m
\
'
1. •' •!'.'• .;, •
. •
•
V
• '
•T
• ;.-
-.•-
1
tx
N
.GRANULAR BACKFILL
:'•';.';:> 4' LD UANHOLE
POINT OF CONTINUOUS OR
MONITOflINC
NOTE: MANHOLE WILL BE EQUIPPED WITH DISCHARGE LINE TO
LEACMATE REMOVAL SYSTEM O»»i7rl DISCMARCC PUMP
(b) Schematic of a monitoring and collection manhole located outside a
unit. (Source: E. C. Jordan, 1984).
Figure 3.7 - Details of Gravity Monitoring System
111-36
-------
«" on LARGER PERFORATED
COLLECTION HEADER
9—
DtAMETER O_LANCXJT MAHHOLt
6' OR LARCER DIAMETER ACCESS UNE
\
/
«' DtAMETE*
/ PERFORATED LATERALS
l~
|
[i
Lkl
C
* m^
2 FLOW DIRECTION
It ' "
t_
/
\
^~
-o
o-
O -
o
j*\
°v
0
— E
— E
c
~>
SITE
f
\
/
Edge of Top Liner
Edge of FML Component
of Bottom Liner
SIDE SLOPE AREA
AUXILL1ART CLEAN OUTS CTTPICAJJ
6 OR LARGER DIAMETER DISCHARGE.
4' DIAMETER MONITORIHC/COLLCCTION MANHOLE
(c) Schematic layout of pipe in a secondary LCS for- a surface
impoundment, (Source: E. C. Jordan, 1984)
Figure 3.7 - Continued
111-37
-------
6.0 Surface Water Collector
i Ml f
M ./ // t/ ,\
i\w-/f\a \ :K/-jno VTV.H i^f va w ;M /, n\\\ AT >
"•
\\ vcctTAT:o:i on
EROSION1 CONTROL HATCRUI.
AND ABOVE SURFACE
30 c,
1
.a •»
''
LO'J PlR.lilAElLITY
LAYER 60cm
SOIL FOR ROOT
cnowrn
CMOVC IXFILTJUTINC \'.iC.-?.
7
INCREASES EFFICIE.'XV Or
DRAZN.-.CE LAVER AN3 MIMV.IZiS
i:;riLTn^Tio:; I::TO 'J::IT
111-38
-------
6.1 Design Quantity
• Computer Code "HELP" will give design (required) flow rate
PRECIPITATION
EV4PO-
TRANSPIRATION
LtochaH collection plpt
TO LEACHATE COLLECTION SUMP
111-39
-------
6.2 Types of Drainage Systems
(a) Granular Soils (designed as before)
(b) Geonets (designed as before)
(c) Geocomposites
• see Table 3.2 for types
• see Figure 3.8 for response
(d) Design example follows
111-40
-------
Table 3.2 - Summary of Gcocomposite Drainage Systems
Manufacturer/Agent
American Wick Drain Corp
BASF Corp
Burcan Industries
Exxon
Geotech Systems
Huesker Synthetic
JDR Enterprises
Mirafi
Monsanto
Nilex
NW Fabrics
Pro Drain Systems
Tensar
Product Name
Amerdrain 480 mat
Enkamat 7010
Enkamat 7020
Enkamat 9010
Enkamat 9120
Hitek 6c
Hitek 20c
Hitek 40c
Tiger Drain
Geotech Drain Board
Ha Te-Drainmatte
J-Drain 100
J-Drain 200
Miradrain 6000
Miradrain 9000
Miradrain 4000
Hydraway Drain
Nudrain A
Nudrain C
Permadrain
PDS20
PDS 40
DC 1100
DC 1200
Core
Structure
Nippled core
Open core
Open core
Open core
Open core
cuspated core
cuspated core
cuspated core
cuspated core
EPS panel
extruded rib
extruded rib
extruded rib
extruded rib
extruded rib
raised cyl. tubes
cuspated
cuspated
cuspated
extruded rib
extruded rib
Core
Polymer
polyethylene
nylon 6
nylon 6
nylon 6
nylon 6
polyethylene
polyethylene
polyethylene
polyethylene
-
polypropylene
polyethylene
polyethylene
polystyrene
polystyrene
polystyrene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
Geolextile
polypropylene
polyester
polyester
polypropylene
polypropylene
polypropylene
polypropylene
-
PES
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
polypropylene
Roll Size (ft)
width/length
4/104
3.2/492
3".2/330
3.0/99
3.0/99
3.0/450
3.6/125
3.5/80
4/100
4.0/4.0
13/328
4/8,25,50
4/8,25,50
4.0/8.0
12,18/400
1.6/49,98
3.6/98
any size
3.7/10-500
3.3/10-250
5.3/100
5.3/100
Thickness
(mils)
375
400
800
400
800
255
785
1575
600
1000
260
250
250
380
380
750
1000
1575
787
-
750
1500
230
240
Crush Strength
(psi)
86
-
69
35
17.5
38
5.5
-
104
125
30
95
18.8
34.7
28
-
-
Flow Rate (gal/min/ft)*
@ 1.45 psi
18
-
26
9.6
22
9
2.3
-
7.2
3
15
15
5
70
28.5
24.1
-
9.6
22
5.5
4
@ 14.5 psi
16
-
2.1
9.6
8
1.25
-
5.8
1.8
-
68
-
-
9.6
22
4.5
3
*The values of flow rate are assumed to be at a hydraulic gradient of 1.0 in which case it is
numerically equal to transmissivity. The values, however, are taken directly from manufacturers
literature where considerable variation in test method, manner of presentation of results,
and concepts involved all might vary.
-------
15
TOO
10
-5 i.c
D
15 2160
20 28BO
0.01
0.10 1.0
Hydraulic gradient
la]
f 10
700
600
500
10.0
OOC
0.0 0.1 0.2 0.3 0.4 0.5 O.C 0.7 O.fc
Thickness of mat, d(in.|
l» I ; I 1 I
0 2b
50 75
Residual thickness, n(r,J
(b)
100
Figure 3.8 -
Flow rate behavior of selected geocomposite drainage systems. (a) Miradrain 6000 at
hydraulic gradients of 0.01 to 1.0; (b) Enkadrain at hydraulic gradient of 1.0; (c)
Enkadrain at hydraulic gradients of 0.006 to O.lO; (d) flow rate behavior of various
commercial drainage geoeomposites; (e) design guide for drainage composites.
-------
Cell Component: Siii^f^e. U*-re« £~<»LLECTU»M / REMOVAL. Sv-»r£M
Consideration '.
T^WSMi-S-ilV.TY,**,^^
TSMA^.M |-FrW6A.o W,rH ^
Required Material Properties
P\AMAfli p~C o InJ <— A,PA<^ITV
DJ^M '"-i '^v 'T1" OAT*
— — ^mm u
T Vl
? ,Zi .So -14
tj RA.TIO
r^ 1 LC fl
1 ^ i qUt n io
•XtPiPtsPviiu^ ]
•]
tt-0
JuiT UJiJCjHT OF" F'LL
(&/f., „)
References:
• \O.O UIOMCj (d ? 7 )
Example:
• C°*tt.o, S.iL^ei^HT, D-4'
• UU'T Uj li^kfr eF ^iv£B Soil J" IZo PcF
• SPAOUC »F ^oLLt«T»« P iPtS" 'to FT
} 6 ' '
( i ] t^ £pip£ p*i i uiuJf-i J p?1 AyiJi^r^ii V i"T Y
— .— ^O^^.l o, -5
|- - 36.5 t-r /f A^X - 4-1*^ MlAt£
1 4- £.p ^,,1 fl '
G' =IZov^» 4So P-SF
(?>") O&TXiM SUJCP. T^^J^^'SSivlTY FR&M L*.& P>^A Tr «
! ^ '5iJ^
r' ' ; 1 1 I | 1 ~ HOtMAt ST«tSS ,f Sf
I ~_ 0 200
• 2000
•- 0 1000
kO I - - • 10100
e - -
^' r a. * A. 1 1 irfX) i ^- ^ o 1 1 *•< 8
> t" "^"-" """-•>>- A JOOOO ^\KJO)fc M~T L" (La/ f{*\
3 (' •o — _ "^ r^ 2 o l / ^^ ^ /
1 ••!-. ° "~° L = -i ,^
1 " ~~I - . ooc>^ 5 M /^>
r,,,o,,, A'^"""t""^ 1
,, 10 .11 i no i»
(
(4s) d*,L<: JLA.TK P^tii^u RA.TIO
T,«« .0004.5
P^ TM<| - 4.tlo-» ^ -^
Example No. 5.\
-------
7.0 Closure Gas Collector and Removal System
7.1 Overview and Quantities
• Types of gases to be removed
• methane (CH4)
• carbon dioxide (CO2)
other (carbon monoxide, ammonia, hydrogen, sulfide,
water vapor)
York, et al. recommend design of 15 to 30 ft3/hr per
1000 ft2 of area based on 23' deep municipal landfill
in Elizabeth, NJ
very site specific
111-44
-------
7.2 Design of System
• Design can use a needle-punched nonwoven geotextile directly
beneath clay
• Gas compatibility (mainly methane) should allow for most types
of geotextile polymers (e.g., PET, PP, PE)
• Design should be based on air transmissivity tests,
i.e. DR = 6aI|OW/ereqd, see Figure 3.9 following
• Alternatively, one could look directly at permeability coefficients
where geotextile air flow is orders of magnitude greater than the
MTG required values, see Figure 3.9 following
111-45
-------
4.0 -
Ua 3.5psi
0 500 1000 1500 2000 2500
STRESS (pif)
(a) Air transmissivity versus applied normal stress for one layer of
Fibretex 600R.
25C-
20C-
150-
100
I I I I
0 5OO IOOO IS.OO 2OOO 25OO
STRESS (ps()
(b) In-plane coefficient of air permeability versus applied normal stress
for one layer of Fibretex 600R.
Figure 3.9 - Air Transmissivity and Permeability of a 12 02/yd Needle
Punched Nonwoven Geotextile
111-46
-------
7.3 Collector and Vent Details
STEEL CLAMP ;
WELDS -x ,„
/ Vi
S»-. V"«'""*
......«** l»V«........
\
./vViSTIC
/
a
CA. „
BOOT SEAL AT FMC
CASKET
\-
VENT TO ATMOSPHERE /V^.\
FILTER
FMC
FbfNCt St>0. AT
OPERATIONAL COVEK
-Air/Ci!
Place Vent Higher than Maximum Liquid Level
at Over-Flow Conditions
Two-Inch Minimum
L Ceotexnle or
Dniruge Composite
Openings in Vent to be Higher thjn
~Top of Berm or Overflow Liquid Level
Air/Cis Vent Assen-fcly
Line
1 Approx. Six-Inches
Wind Cowl
ITI ||| .s Geomembrjne
^^p^^qErrr fi^^ss,
^^^b^^^-^^l^^
Concrete
Bond Skid of Vent to Liner
C« Flow
111-47
-------
SESSION IV - COMPUTER SOFTWARE SUPPORT
Robert Landreth, Gregory Richardson,
Robert Koerner, and David Daniel
-------
HWERL COMPUTER PROGRAMS
Robert Landreth
IV-1
-------
HWERL computer programs
SOILINER Model
Documentation and User's Guide for Version 1, EPA 530/SW-86-006a
Software on one 5-1/4 inch, DS/DD disk for IBM XT.AT or IBM compatible PCs
The SOILINER computer model is a finite-difference approximation
of the highly nonlinear, governing equation for one-dimensional flow in the
vertical dimension. The program simulates the dynamics of infiltration
through a compacted soil liner beneath impounded liquid for a variety of
scenarios. Output of the program is presented through Lotus 123.
Geotechnical Analysis for Review of Dike Stability (CARDS)
Technical Manual, EPA 600/2-86-109b\
Software on four 5-1/4 inch, DS/DD disk for IBM XT.AT or IBM compatible PCs
(with a hard disk, a math co-processor chip, and a color or graphics monitor).
The GARDS computer program is a user friendly software package
for the geotechnical analysis of dikes at hazardous waste sites. The
program was designed for use by regulatory personnel to evaluate existing
and planned earth dike structures at hazardous waste facilities. The
program's main features include slope stability analysis, settlement
analysis, and liquefaction potential for various hydraulic conditions.
Hydrologic Evaluation of Landfill Performance (HELP) Model
Volume I - User's Guide for Version I, EPA/530-SW-84-009
Volume II - Documentation for Version I, EPA/530-sw-84-010
Software on five 5-1/4 inch, DS/DD disk for IBM XT.AT or IBM compatible PCs
(with a hard disk, at least 384k bytes of main memory (RAM), a math co-
processor chip, and a color or graphics monitor).
The Hydrologic Evaluation of Landfill Performance (HELP) program
facilitates the rapid economical estimation of the amount of surface runoff,
subsurface drainage, and leachate that may be expected to result from the
operation of a wide variety of possible landfill designs. The program
models the effects of hydrologic processes including precipitation, surface
storage, runoff, infiltration, percolation, evaptranspiration, soil moisture
storage, and lateral drainage using a quasi-two-dimensional approach.
Version 2.0 of the HELP model is currently being evaluated through a select
program testing group. The model is anticipated to be released to the general
public along with documentation in late summer 1988.
IV-2
-------
EXPERT SYSTEMS CURRENTLY DEVELOPED OR UNDER DEVELOPMENT
AT THE CENTER HILL RESEARCH FACILITY
FLEX - Flexible Membrane Liner Advisory Expert System -
Evaluates EPA Method 9090 data to determine FML
compatibility with leachate. Status: preliminary
version has been demonstrated; final version due by
6/1/88.
Software on two 5-1/4 inch, DS/DD disk for IBM XT.AT or IBM compatible PCs
(with a hard disk, 640KB RAM, and a color or graphics monitor).
GM - Geosynthetic Modelling System -
Automates engineering design problems for various
geosynthetic materials applications related to
hazardous waste containment. Status: final version
ready for distribution.
Software on one 5-1/4 inch, DS/DD disk for IBM XT.AT or IBM compatible PCs
(with a hard disk, 640 KB of RAM, and a color or graphics monitor).
WAPRA - Waste Analysis Plan Review Aid -
Assists in the review of waste analysis plans for
RCRA Part B permit applications. Incorporates rules
for determining compatibility of wastes processed in
the same waste stream and feasibility of sampling
methods. Also includes report generation functions.
Status: preliminary version has been demonstrated;
work has begun identifying shortcomings and refining
the system.
Software on two 5-1/4 inch, DS/DD disk for IBM XT,AT or IBM compatible PCs
(with a hard disk, 640KB of RAM, and a color or graphics monitor).
TECHSCRN - Cleanup Technology Screening System -
Determines the feasibility of various cleanup
technologies at uncontrolled hazardous waste
sites based upon contaminant and site
characteristics. Status: prototype has been
demonstrated; further development pending Agency
requirements determination.
Software on one 5-1/4 inch, DS/DD disk for IBM XT,AT or IBM compatible PCs
(with a hard disk, 640 KB of RAM, and a color or graphics monitor).
IV-3
-------
DIKE - Dike Stability System -
Evaluates the stability of surface impoundments
based on geotechnical design parameters. Status:
final version is ready for distribution however due
to software licensing restrictions each copy costs
the Agency approximately $250.
Software on four 5-1/4 inch, DS/DD disk for IBM XT,AT or IBM compatible PCs
(with two double sided disk drives or one disk drive and a hard disk,
recommended is a 640KB-hard disk configuration, and a color or graphics
monitor). The DIKE(2.0) system was developed using INSIGHT II + as the expert
system shell and the INSIGHT II + package is therefore required to execute the
program. INSIGHT II + is no longer available and has since been replaced by the
L5 shell.
EXP-CES - Closure Plan Evaluation Expert System -
Assists in the review of hazardous waste facility
closure plans. This system is comprised of three
modules which evaluate the vegetative cover,
final cover, and leachate collection and removal
system of a RCRA facility scheduled for closure.
Status: preliminary versions have been
demonstrated; final version due by 6/1/88.
Software on four 5-1/4 inch, DS/DD disk for IBM XT.AT or IBM compatible PCs
(with a hard disk, 640KB of RAM, and a color or graphics monitor).
IV-4
-------
FLEX
FLEXIBLE MEMBRANE LINER ADVISORY EXPERT SYSTEM
Robert Landreth
IV-5
-------
FLEX
Flexible Membrane Liner Advisory
Expert System
Expert System
A system designed to provide advice
concerning specific issues.
Series of "if....then" statements.
IV-6
-------
Why do we need expert systems?
- consistency
^ documents the bases or criteria
L. latest research/regulations
A training tool
A time
Flex can be used for:
A PVC
A CSPE
A HDPE
IV-7
-------
What does it do?
provides a report as system runs
lists any inconsistencies
lists any values indicating
the liner substandard or incompatible
What won't the system do?
- replace the permit writer/reviewer
^ to be used as a guide
Status
Field tested with experts
Now in selected beta testing
IV-8
-------
CARDS
GEOTECHNICAL ANALYSIS FOR
FOR REVIEW OP DIKE STABILITY
Gregory Richardson
IV-9
-------
SEMINAR - Requirements for Hazardous Waste
Landfill Design, Construction and Closure
PROGRAM - CARDS: Geotechnical Analysis for
Review of Dike Stability
AUTHOR - A. Bodocsi, Associate Professor
Department of Civil Engineering
University of Cincinnati
Cincinnati, Ohio 45220
SOURCE - University of Cincinnati
Center Hill Laboratory
5995 Center Hill Road
Cincinnati, Ohio 45224
$35.00 for 160 pg manual and 4 diskettes
HARDWARE - IBM PC/XT or compatible
2M hard disk space
IBM color graphics adapter
APPLICATION - CARDS is an interactive program developed for the
analysis of dikes. The program allows the user to create one data
file describing the geometry and material properties of the soils
forming the dike and then perform the following analyses:
1) steady state seepage through the dike to determine both
the steady state piezometric surface and the quantity of
discharge through the dike,
2) slope stability of the dike using both circular and wedge
failure surfaces, and incorporating the piezometric
surface calculated in 1),
3) settlement analysis to compute total and differential
settlements beneath the dike, and
4) a liquefaction analysis to determine the zones having the
greatest potential for liquefaction during an earthquake.
The program provides for data input, editing, and both graphical
and printed verification. The graphics requires a standard ISM
color graphics adapter only. The input block allows the following
options: data entry with full text explaination of input (slow),
data entry without text explanation (fast), and entry using an
existing data file.
CARDS produces a summary table of the four analyses indicating
actual design factors-of-safety vs minimum recommended values.
IV-10
-------
THEORIES - Each of the four analytical blocks is based on conventional
Geotechnical theories and, in two cases, actual sofware programs.
Hydraulics: The hydraulics analysis uses the finite element
program SEEP. This program was developed by Jim Duncan at
Virginia Tech and incorporates an algorithm that automatically
searches for the correct phratic surface. The algorithm was first
used by Shlomo Neuman at University of Arizona. The CARDS program
automatically generates the SEEP input file so the user does not
have to generate the finite element mesh nor be familiar with the
many options available with the SEEP program.
Slope Stability: The slope stability block uses the phreatic
surface defined by the hydraulics block and performs either a
circular slip analysis (Modified Bishop) using the REAME code by
Yang Huang at University of Kentucky or wedge analysis using the
method in NAVFAC Manual 7.1. Both circular and wedge programs
search for the surface having the lowest factor-of-safety against
sliding.
Settlement Analysis: The settlement analysis block calculate the
consolidation of foundation soils caused by the weight of the
dike. The analysis uses Boussinesq's theory to calculate stresses
within the subgrade and then uses Terzaghi's one-dimensional
consolidation theory to calculate settlements. Soil properties
required included initial void ratio, compression and
recompression indexes, and the overconsolidation ratio.
Liquefaction Analysis: The liquefaction analysis is performed
using the empirical relationships developed by Harry Seed of the
University of California at Berkeley and applies only to those
sites having sand or silty sand deposits below the groundwater
level. The average Standard Penetration Resistance, N, oust be
input for each layer in question.
CASE m ™PLE 1 file: BASE2EX1
Hydraulic Condition 2! Shallow Static Ground Water Table
Unconsolidated Undrained Soil Parsneters
Factor of Safety : 1,24, Failure Center: ( 539 , 150 ), Radius: 110
\
\
\
\
\
\
X
IV-11
-------
SHALLOW SEEPAGE CASE FOR EXAMPLE i File; BASE2EX1
Hydraulic Condition 2! Shallow Static Ground SJatan1 Tails
llnconsolidated IJndrained Soil Parameters
Factor of Safety : 1,13
( 371 ,-2? ) SCALE,; 1 inch: 33 fset
* *
* GARDSSUMMARY *
* *
* File: BASE2EX1 Date: 01-01-1980 Time: 03:49:27 *
* Project: SHALLOW SEEPAGE CASE FOR EXAMPLE 1 *
* Hydraulic Condition 2: Shallow Seepage *
* *
* *
* Rotational Failure Analysis Safety Factor *
* *
* Unconsolidated Undrained Case 1.24 *
* Consolidated Drained Case Not Run *
* Consolidated Undrained Case Not Run *
* *
* Translational Failure Analysis Safety Factor *
* „ _ *
* Unconsolidated Undrained Case 1.13 *
* Consolidated Drained Case Not Run *
* Consolidated Undrained Case Not Run *
*_.. *
* Settlement Analysis Feet of Settlement *
* *
* Maximum Settlement at the center line 0.54 *
* *
* Maximum Differential Settlement 0.45 *
* from the left toe to the center-line. *
* Maximum Differential Settlement 0.45 *
* from the right toe to the center-line. *
* _ _*
* Liquefaction Analysis Not Run *
IV-12
-------
HELP
HYDROLOGIC EVALUATION OF LANDFILL
PERFORMANCE MODEL
Gregory Richardson
IV-13
-------
SEMINAR - Requirements for Hazardous Waste
Landfill Design, Construction and Closure
PROGRAM - HELP: Hydrologic Evaluation of Landfill
performance Model
AUTHOR - Paul R. Schroeder
WREG, Environmental Lab.
USAE Waterways Experiment Station
P.O. Box 631
Vicksburg, MS 39180
(601) 634 3709
SOURCE - Paul R. Schroeder
No charge, but need to provide 8 formatted 5.25" diskettes
HARDWARE - IBM PC/XT or compatible
384 K RAM
Math Coprocessor
Hard Disk Drive
APPLICATION - The HELP model was developed to assist in estimating the
magnitude of water-balance components and the height of water
saturated soil above the barrier layers. The model is essentially
that of one-dimensional flow. Two dimensional flow is modeled in
a quasi fashion by defining layers having both a vertical and
lateral flow of moisture (e.g. drainage layers). The current HELP
model (Version 2) allows up to 12 layers and and additional 4
barrier soil liners. Three types of layers are provided by H3L?;
vertical percolation, lateral drainage, and barrier soil liner.
HELP is unique in providing a significant amount of
climatological data for 184 cities throughout the country. This
allows the user to use extended evaluation periods without having
to assemble large quantities of data. In addition to these 5 year
climatological data files, HELP also inorporates a syr.thatic
weather generator developed by the Agricultural Research Service.
The synthetic generator produces daily values for precipitation,
minimum and maximum temperature, and solar radiation.
THEORY - The HELP model incorporates a chain of existing models _to
follow the moisture from its arrival as percipitation to its
eventual end as leachate or drainage. The methods for defining
the amount and history of rainfall have been previously covered.
Once the rain reaches the ground, the Soil Conservation Service
(SCS) method is used to partion incoming rain between runoff and
infiltration. Infiltration is the difference between the daily
precipitation and SCS runoff, less the daily surface evaporation.
If the daily temperature is below 0° C, the precipitation is
stored as snow and does not contribute to the infiltration of
runnoff until the temperature rises above 0 C.
IV-14
-------
Evapotranspiration is a function of energy available, vegetation,
soil evaporation coefficient, and soil moisture content. The
potential evapotranspiration is modeled using a modified Penman
method that includes variables for the slope of the saturation
vapor pressure and the net daily solar radiation.
Moisture is routed vertically through the layers by a
simultaneous solution of Darcy's law and the equation of
continuity. Unsaturated hydraulic conductivity is modeled as a
function of soil moisture by a form of the Brooks-Corey equation
that relates the conductivity to a dimensionless soil moisture
raised to a power.
The lateral drainage layers can incorporate drainage lengths up
to 2000 ft and slopes up to 30 %. The soil barrier layers can
include a membrane barrier (e.g. composite liner) but a % leakage
value must be assigned to the FML. No criteria exists for
defining the true value for such leakage.
Extensive default values are provided for all input variables!!
PRECIPITATION
EVAPOTRANSPIRATION
VEGETATION j RUNOFF
t INFILTRATION
CD VEGETATIVE LAYER
o
at
a.
m
(2) LATERAL DRAINAGE LAYER LATERAL DRAINAGE
ifanu COVER) ~ •
!— SLOPE
BARRIER SOIL LAYER
O
o
a.
<
o
PERCOLATION
(FROM BASE OF COVER)
® WASTE LAYER
LATERAL DRAINAGE
LATERAL DRAINAGE LAYER (|rRQM 3AS£ QF LANOFILL)
MAXIMUM DRAINAGE DISTANCE
'ERCCLAT10N (FROM BASE OF
IV-15
-------
SESSION V - CLOSURE DESIGN
Gregory Richardson
-------
SECURING a COMPLETED LANDFILL
SESSION V
EPA SEMINAR
CAP vs LINER DIFFERENCES
o Water not leachate
o Low normal stress
4
o Potential subsidence
o Repair reasonable
MTG MINIMUM CAP PROFILE
o 2 ft vegetated top cover
o 1 ft drainage layer
o Low permeability cap
>20 mil synthetic (option)
>2 ft clay liner
o Gas control layer (optional)
V-l
-------
CLOSURE DESIGN ELEMENTS
o Infiltration rate
o SWCR Design
o Gas collection
o Biotic layer
o Erosion control
HYDROLOGIC EVALUATION o£ LANDFILL
PERFORMANCE (HELP) MODEL
o Layer types
vertical percolation
lateral drainage
waste
barrier
o 12 layer capacity
o Actual & synthetic weather data
V-2
-------
o
cr
a.
oa
en
PRECIPITATION EVAPOTRANSPIRATION
[-VEGETATION j RUNOFF
D VEGETATIVE LAYER
LATERAL DRAINAGE LAYER
BARRIER SOIL LAYER
WASTE LAYER
LATERAL DRAINAGE
(FROM COVER)
L-SLOPE
PERCOLATION
(FROM BASE OF COVER),
cc
LLJ
o
Q_
<
0
o
IT
Q.
03
LATERAL DRAINAGE LAYER
LATERAL DRAINAGE
(FROM BASE OF LANDFILL)
BARRIER SOIL LAYER
MAXIMUM DRAINAGE DISTANCE
(E
LJ
T
PERCOLATION (FROM BASE OF LANDFILL)
Figure 2. Typical landfill profile.
V-3
-------
LEGEND
HELP SIMULATION
'FIELD MEASUREMENT
JAN
1977
FIG. 3. Cumulative Comparison of HELP Simulation and Field Measurements
University of Wisconsin-Madison Uncovered Cell
Tvo verification studies of the HELP model have been completed and
published by the USEPA. The first is entitled -Verification of the Lateral
Drainage Component of the HELP Model Using Physical Models' and has a
document number of EPA 600/2-87-049. The second is entitled -Verification^
of the HELP Model Using Field Data' and has a document number of EPA 600/2-
87-050. Their NTIS accession numbers are PB87-227104 and PB87-227518,
respectively.
V-4
-------
SURFACE WATER COLLECTION/REMOVAL
(SWCR) DESIGN
o Cover stability
o Puncture resistance
o Impact of settlement
strains
hydraulics
o Cover stability
o Impact of settlement
o Puncture resistance
INTURIOR B1.ARMS
V-5
-------
• OCKXMUI •oininurw
eammiw
ra.fi.
wt.fi.
6 osy Ceotextile
12 osy Geotextile
18 osy Ceotextile
(KOERNER.1986)
n.n*
wt.n
mt.T>m ai.fi. nc.fi. nn.fi.
a. PUNCTURE RESISTANCE
cn.n» nc.n*
1 J = .738 ft-lb
b. IMPACT RESISTANCE
Figure 3.8 Survivability of Common FMLs
V-6
-------
Cell Component: ^)unf^e W*jeTfl£'S'^ A,0o-J£
( _ — «>.
•r""J]L"lI(L
M I- °*J ^
PR " ^
. CoUEcTioM/^EMoVAJ- 5Y"3TE.M
EvALL/ATE •SLIOitoc; SrAftlLlTY oF
DfSiqu RiTio A<^Aiiujr SHEAR
Range
k>- U»o ">/)U^
/2 -,
/> 'li
~"2
iJfiS »'
s»
Test
Uie6 U'PTH
oP£ of Co\li
W<^R sy x 144
Example No. 5-2.
-------
I
00
Cell Component: SURFACE UA.TEB: Coi\.tc-r«*j j REMOVAL SVSTEM
Consideration:
ABILITY <,F
IkJ 5*4 £ A, H
-------
Cell Component: FLEXIBLE MLMBR^B
Consideration' SETTL
: V
ERIFY
r° *L»WI
Onli MIG Mmnin
Range
Test
WIDEUlOffl
Standard
Analysis Procedure:
(1^ E»PMA.TE.
• DEPTH
»eiTLt
lM ^7. )
l^'IM U s-1
x. uA,-»re
~ DtpTM
IM FK»H pig 3/j
M
z
<
at
o
AT
O(ul*( TtcmiCh McxM
yK-
^T
o.» o.l o.J
SETTLEMENT RATIO, S/2L
Design Ratio:
References:
KMIP-^H IE.LD
Example:
IV6
- 50 FT
tTe°ne.Tay or SETTIE. MEMT FeAirua £
PEPrM^ 5% x 50' -
SEE Fi
-------
CONDENSATE DRAIN TO COLLECTOR
Gas Flow
-Gas Well
CONDENSATE DRAIN TO WELL
Gas Flow
Water Flow
MOISTURE CONTROL
(after Rovers, et al)
Figure 5.6 Water Traps in Vapor Collector Systems
*
The gas collection system for a controlled hazardous waste facility
differs from that typically designed for a sanitary facility in that the
use of wells, pumps, etc. to accelerate the collection or generation of
gases is not advisable due to the possible presence of hazardous vapors and
V-10
-------
100%
0.6 0.8 1.0
NORMAUZfD PRESSURE RATIO
Figure 5.6 Air and Water Transmissivity in a Needled Nonwoven Geotextile
STEEL CLAMP JJ
BOOT SEAL AT FMC
CASKET
FILTER
1 — FMC
FLANGE SE>U AT FMC
OPERATIONAL COVER
Figure 5.7 Gas Vent Pipes - Details
V-ll
-------
BIOTIC BARRIER
o Prevent intrusion of burrowing
animals (gophers, mice..)
o Danger of entrance from below facility
o Rigid FML give good resistance
o Gravel/rock system acts as collector
FUNCTIONS of_ VEGETATIVE LAYER
o Prevent wind & water erosion
o Minimize percolation to waste
o Maximize evapotranspiration
o Enhance aestetics
o Self sustaining ecosystem
WATER LOSS
(UNIVERSAL SOIL LOSS EQUATION)
X = RKSLP
X = soil loss
R = rainfall erosion index
K = soil erodibility factor
S = slope gradient factor
L = slope length factor
C = crop management factor
P = erosion control practice
V-12
-------
VEGETATION
TOPSOIL
(60 CM)
GRAVEL FILTER
(30 CM)
Bionc
BARRIER
COBBLESTONE
(70 CM)
PROTECTIVE LAYER
FMB
COMPACTED SOIL
(90 CM)
GAS VENT
(30 CM)
WASTE
OPTIONAL BIOT1C BARRIER LAYER.
V-13
-------
TABLE 5. APPROXIMATE VALUES OF FACTOR K FOR
USDA TEXTURAL CLASSES
11
Texture class
Sand
Fine sand
Very fine sand
Loamy sand
Loamy fine sand
Loamy very fine sand
Sandy loam
Fine sandy loam
Very fine sandy loam
Loam
Silt loam
Silt
Sandy clay loam
Clay loam
Silty clay loam
Sandy clay
Silty clay
Clay
Organic
0.55*
K
0.05
.16
.1*2
.12
.21*
.1*1*
.27
.35
.»*7
.38
.1*8
.60
.27
.28
.37
.114
.25
matter
2%
K
0.03
.11*
.36
.10
.20
.38
.2k
.30
.1*1
.31*
.1*2
.52
.25
.25
-32
.13
.23
0.13-0.
content
k%
K
0.02
.10
.28
.08
.16
.30
.19
.21*
.33
.29
.33
.1*2
.21
.21
.26
.12
.19
29
The values shown are estimated averages of broad
ranges of specific-soil values. When a texture is
near the borderline of two texture classes, use
the average of the two K values.
o
-------
WIND EROSION
X' = I'K'C'L'V
X' = annual wind erosion
I' = field roughness factor
K' = soil erodibility index
C' = climate factor
L' = field length factor
V' = vegetative cover factor
SURFACE VEGETATIVE LAYER
o Local agricultural extension agent or
DOT provide good recommendations
o Verify impact of SWCR in arid and
semi-arid regions
o Generally use native grasses
ADDITIONAL CONSIDERATIONS
o Filter layers
o Freeze-thaw
o Cap-Liner connection
V-15
-------
FROST DEPTH
Figure 12. Regional depth of frost penetration in inches.
11
V-16
-------
___ L^-«-
| U,
'—Secondary Anchoi
1—Cap Anchor Trench
A) Geosynthetic RCRA Cell Profile
Extruiion W«(
X
FMC
B) "Sealed" Geosynthetic Cell Profile
Figure 5.1 Geosynthetics in RCRA Double FML Cell Profile
V-17
-------
SESSION VI - CONSTRUCTION,
QUALITY ASSURANCE AND CONTROL
David Daniel
and
Gregory Richardson
-------
CONSTRUCTION OP CLAY LINERS
David Daniel
VI-1
-------
Second Part:
- Construction Criteria
- Factors To Be Considered
- Key Construction Criteria
- Excavation and Placement
- Compaction
- Protection
- Quality Assurance
- Test Fill
Important Compaction Variables:
• Soil Water Content
• Type of Compaction
Compactive Effort
• Size of Clods
• Bonding Between Lifts
VI-2
-------
Hydraulic
Conductivity
Dry Unit
Weight
Molding Water Content
Kev Factor:
Fate of Clods and
Inter-Clod Pores
VI-3
-------
10
-5
10
(A
\
E
u
io
7
10
-8
Optimum w —
Static
Compaction
Kneading Compaction
15 19 23 27
Molding w (%)
12
16 20
Molding Water Content (%)
VI-4
-------
O)
I
^J_
><
;>
'o
c
o
O
o
"5
to
10
15
20
25
Molding Water Content (%)
Q
0.2-in. Clods
0.75-in. Clods
10 15 20 25
Molding Water Content (%)
VI-5
-------
Influence of Clod Size:
Hydraulic Conductivity (cm/s)
Molding
W.C. (%} 0.2-in. Clods 0.75-in. Clods
12 2x10-8 4x10-4
16 2x10-9 1x10-3
18 1x10-9 8x10-10
20 2x10-9 7x10-10
Need to Bond Lifts
VI-6
-------
Fully-Penetrating Feet;
CJ
Loose Lift
of Soil
Compacted Lift
Partly-Penetrating Feet:
Loose Lift
of Soil
.
Compacted Lift
/ t ' t S
Parallel Lifts
VI-7
-------
Parallel Lifts
Horizontal Lifts
Sandy Soil
Construction of Clay Liners:
1. Remoldability of Clods
- Water Content
- Undrained Shear Strength
2. Remolding Capability of
Compaction Equipment
- Type of Roller
- Weight of Roller
- Lift Thickness
- Number of Passes
VI-8
-------
Construction:
1. Location of Borrow Source
- Boreholes, Test Pits
- Laboratory Tests
2. Excavation of Borrow Soil
3. Preliminary Moisture Adjustment;
Amendments; Pulverization
4. Stockpile; Hydration; Other
5. Transport to Construction Area;
Surface Preparation
6. Spreading in Lifts; Breakdown
of Clods
7. Final Moisture Adjustment;
Mixing; Hydration
8. Compaction; Smoothing of
Surface
9. CQA Testing
10. Further Compaction, If Necessary
VI-9
-------
Soil - Bentonite Liners:
1. Determine Amount of Bentonite
Needed Using Laboratory Tests
2. Increase Amount to Account for
Construction Irregularities
3. Mix Bentonite with Soil
A. Spread Bentonite on
Loose Lift of Soil and
Mix with Disc (Multiple
Passes in Opposite
Directions); Adjust the
Moisture Content
B. Mix in Pugmill; Spread in
Thin Lifts; Adjust Moisture
Content, If Necessary
4. Compact the Mixture
VI-10
-------
Case Histories
Cfl
0>
CO
O
»•—
o
(5
I
3
Z
In Situ Hydraulic Conductivity, cm/s
Protection of Liner:
1. During Construction
- Desiccation Control
- Proof Rolling for Erosion
Control
- Protection from Freezing
2. After Construction
- Protection from Desiccation
- Protection from Freezing
VI-ll
-------
Construction Quality Assurance:
1. An Effective CQA Plan
2. Knowledgeable and Experienced
Inspectors/Supervisors
3. Appropriate Construction Quality
Control Testing (CQC)
Construction Quality Control Tests:
Atterberg Limits
Grain Size Distribution
Compaction Curve
Hydraulic Conductivity of
Lab-Compacted Soil
Material
Tests
Moisture Content
Dry Density
Hydraulic Conductivity of
"Undisturbed" Sample
Tests on
Prepared and
Compacted
Soil
VI-12
-------
TABLE 5-9. RECOMMENDATIONS FOR CONSTRUCTION DOCUMENTATION OF CLAY-LINED
LANDFILLS BY THE WISCONSIN DEPARTMENT OF NATURAL RESOURCES
1.
Item
Clay borrow source
testing
Testing
Grain size
Moisture content
Atterberg limits
Frequency
1,000 yd3
1,000 yd3
5,000 yd3
2. Clay liner testing
during construction
3. Granular drainage
blanket testing
(1iquid 1imit and
plasticity index)
Moisture-density curve
Lab permeability
(remolded samples)
Density
(nuclear or sand cone)
Moisture content
Undisturbed permeability
Dry density
(undisturbed sample)
Moisture content
(undisturbed sample)
Atterberg limits
(liquid 1imit and
plasticity index)
Grain size
(to the 2-micron
particle size)
Moisture-density curve
(as per clay borrow
requirements)
Grain size
(to the No. 200 sieve)
Permeabi1ity
5,000 yd3 and all
changes in material
10,000 yd3
5 tests/acre/lift
(250 yd3)
5 tests/acre/lift
(250 yd3)
1 test/acre/lift
(1,500 yd3)
1 test/acre/lift
(1,500 yd3)
1 test/acre/lift
(1,500 yd3)
1 test/acre/lift
(1,500 yd3)
1 test/acre/lift
(1,500 yd3)
5,000 yd3 and all
changes in material
1,500 yd3
3,000 yd3
Source: Gordon et al., 1984.
VI-13
-------
0.95 (Y.)
a max
Zero Air Voids
Acceptable
Range
w
opt
w
CO
c
0)
Q
Acceptable
Range
Molding Water Content
VI-14
-------
Important Details:
• Sampling Pattern
• Bias in Some Tests
Outliers
Random Sampling:
1
13
25
37
49
2
14
26
38
50
3
15
27
39
51
4
16
28
40
52
5
17
29
41
53
6
18
30
42
54
7
19
31
43
55
8
20
32
44
56
9
21
33
45
57
10
22
34
46
58
11
23
35
47
59
12
24
36
48
60
Bias in Tests:
• Nuclear Density Tests
• Nuclear Moisture Content Tests
• "Quick" Moisture Content Tests
• Clay Content Tests
• Hydraulic Conductivity of
"Undisturbed" Samples
VI-15
-------
CO
c
g
'-co
CO
_Q
O
(D
_Q
E
Standard
Deviation
(cK
Mean
Value of Parameter
Minimum
CO
c
g
'-i— >
03
0)
CO
.a
O
CD
JD
E
Standard
Deviation
Mean
Dry Density
VI-16
-------
x/q Percent Outliers
0 50
1 16
2 2.3
3 0.1
Test Fills:
- Dimensions:
- At Least 2-3 Roller Widths
Wide
- Length Usually about Twice
the Width
- Thickness Usually 2 or 3 ft
- Materials and Construction
Practices the Same as those
Proposed for Full-Sized Liner
- In-Situ Hydraulic Conductivity
Testing Is Required to Confirm
that Materials and Construction
Practices Are Appropriate
VI-17
-------
I
M
00
Collection
Pit
Gravel to Load Clay
to Evaluate Effect of
Overburden Stress
Compacted
Clay
Sealed
Infiltrometer
Collection Pan Lysimeter
Underdrain
Geomembrane
-------
CONSTRUCTION OF FLEXIBLE MEMBRANE LINERS
Gregory Richardson
VI-19
-------
CONSTRUCTION QA/QC
FLEXIBLE MEMBRANE LINERS
Gregory Richardson
S&ME
ELEMENTS of_ CQA PROGRAM
o resposibility and authority
o CQA personnel qualifications
o Inspection Activities
o Sampling Strategies
o Documentation
FML - INDIVIDUAL RESPONSIBILITIES
o Engineer-design of component
o Engineer-prep, specifications
o Manf/Installer-fabrication
o Installer / Contract .-installation
o Manufact./Installer-QC of FML
o Owner/Engineer-QA of FML
VI-20
-------
Construction Quality Control
(CQC)
A planned system of inspections performed
by the contractor to control the quality
of construction
CONSTRUCTION QUALITY ASSURANCE
(CQA)
A planned system of activities performed
by the owner to assure that the facility
is constructed as specified in the design
INSTALLER QUALIFICATIONS
o Company - supply/install at least
10M sqft similiar FML
o Supervisor - responsible charge of at
least 2M sqft same FML
VI-21
-------
CQA OFFICER
Qualifications: PE or equivalent with
"sufficient" practical, technical
and managerial experience
KEY TRD RECOMMENDATIONS
o Checklist to assure all facility
requirements are met
o Specific plan to be used during construction
for observation, inspection, and testing
o A qualified auditor should review output of
CQA program
GENERAL SPECIFICATIONS
o Document control
o Raw polymer
o Manufactured sheet
o Delivery/Storage
o Installation
o Sampling
VI-22
-------
PRECONSTRUCTION CQA MEETING
o Review specs and CQA plan
o Verify qualifications
o Define acceptance
o Agree on repair method
RAW POLYMER SPECIFICATIONS
o Density (ASTM D-1505)
o Melt Index (ASTM D-1238)
o % Carbon Black (ASTM D-1603)
o TGA or DSC
"fingerprint"
MANUFACTURED SHEET SPECIFICATIONS
o Thickness (ASTM D-1593)
o Tensile Properties (ASTM D-638)
o Tear Resistance (ASTM D-1004)
o Carbon Black Cont. (ASTM D-1603)
o Carbon Black Disp. (ASTM D-3015)
o Dimensional Stability (ASTM D-1204)
o Stress Crack Resistance (ASTM D-1693)
VI-23
-------
SHIPPING CONSIDERATIONS
o High crystaline FML not folded
o Folded FML placed on pallets
o ALL FML protected with covering
Shipping Roll Identification
1-name of manufact./fabricator
2-product type
3-product thickness
4-manuf. batch code
5-date of manufacture
6-physical dimensions
7-panel number
8-direction for unrolling
STORAGE CONSIDERATIONS
o Secure Area
-man or animal
-dirt, dust, water
-extreme heat
o Prevent
-blocking
-loss of plasticizer
-curing
VI-24
-------
FML BEDDING CONSIDERATIONS
o Adequate Compaction
90% modified Proctor
95% standard Proctor
o Surface free of rocks, roots, water
o Smooth roll subgrade
o No desication cracks
o Chemically compatible herbicide
FML PANEL PLACEMENT
o Unfold/roll per delivery ticket
o Minimize 'sliding' of FML
o Limit to 1 days seaming
o Confirm panel overlap
o Inspect for defects
FML SEAMING
o Clean membrane
o Acceptable weather
o Firm foundation
o Qualified seamer
o Seam testing
VI-25
-------
LAP SEAM
LAP SEAM WITH GUM TAPE
TONGUE and GROOVE SPLICE
factory
EXTRUSION WELD LAP SEAM
FILLET WELD LAP SEAM
DOUBLE HOT AIR or WEDGE SEAM
adhesive
gum tape
vulcanized \P^^5SJ/_t3S
Figure 3.6 Configurations of Field Geomembrane Seaias
SHEAP TEST
1
I
>!
|
I
PEEL TEST
Figure 3.7 Seam Strength Tests
VI-26
-------
SAMPLING CRITERIA
o 100%
o Judgemental
o Statistical
CONTINUOUS (100%) TESTING
o Visual
o NDT
o DT on all startup seams
NDT SEAM TESTS
o Air lance
o Vacuum box
o Pressurized dual seam
o Mechanical point stress
o Electronic
JUDGEMENTAL TESTING
o Dirt/debris evident
o Excessive grinding
o Moisture
VI-27
-------
PANEL PLACEMENT LOG
Pan«l Number
Weather:
Date/Time
Temperature.
Wind-
Subgrade Conditions i
Line & Grade: ^___
Surface Compaction.
Protrusions
Ponded Water
Dessication
Panel Conditions :
Transport Equipment; _ ,
visual Panel Inspection:
Temporary Load ing :
Temp. WeIds/Donds:
Temperature
Damages:
-Seam Detoils-
Scaaiing Crews :
Seam Crew Testing:
Figure 6.5 Panel Placement Log
Table 6.3 Overview of Nondestructive Geomembrane Seam Tests
after Koerner and Richardson(1987)
Nondes t ruct ive
Test Method
1. air lance
2. mechanical
point
(pick)
stress
3. vacuum
chamber
(negative
pressure)
**. dual seam
(posit ive
pressure)
5. ultrasonic
pulse echo
6. ultrasonic
impedance
7. ultrasonic
shadow
Pr narv User
yes
yes
yes
yes
Engr.
yes
yes
yes
yes
yes
Pjrty
yes
yes
yes
Cost of
Equipment
5200
nil
5 1000
5200
55000
57000
55000
Speed
of
Tests
fast
fast
s low
fast
mod .
mod .
mod.
Cost
of
Tests
nil
nil
v. high
mod .
hi,,,
high
high
Type of
Result
yes-no
yes-no
ye:, n.i
es-no.
' '
yus-nu
qua 1 it Jt ive
.
Record in^
Method
mjnud 1
UI.UIUJ 1
manmrl
ju L uin.it l e
jutunut i^
Oper.il.oi-
v. liiKh
lii^l,
Ini'.l'
low
unknown
K
-------
GEOMEMBRANE SEAM TEST LOG
SCAM
No.
SEAM
LENGTH
CONTINUOUS TE5TIN6 DESTRUCTIVE TEST
VISUAL
INSPECT
AIR
TEW.
TEST
METHOO
PRESSURE
INIT/FINAL
PEEL
TEST
SHEAR
TEST
LOCATION
1
1
DATE
TESTED
9V
Figure 6.6 Geomembrane Seam Test Log
GEOMEMBRANE REPAIR LOG
DATE
SEAM
PANELS
LOCATION
MATERIAL
TVPE
DESCRIPTION of DAMAGE
TVPE Of
PEPAIS
REPAIR TEST
TYPE
TESTED
B»
Figure 6.7 Geomembrane Seam Repair Log
VI-29
-------
STATISTICAL TESTING (DT)
o Minimum 1/500 ft seam
o Minimum I/seam
o Minimum 1/shift
o No outlier criteria
SAMPLE IDENTIFICATION/DISTRIBUTION
o Identification - seam ft plus location
along seam
o Distribution of samples
-DT in field
-Owners files
-Installers files
SEAM REPAIR CRITERIA
o Minimum Length: repair must be bounded
by successful seam tests
o Repair Methods
-Capstrip
-Grind/re weld
o Post testing of repair
VI-30
-------
WEATHER - SEAM CRITERIA
o No Rain
o No Dust
o Minimum 50o
o No excessive wind
ANCHORAGE - SEAM CRITERIA
o Anchor trench left open until
seam is completed
o Anchor trench filled in morning
to reduce bridging of FML
RECORD (As-Built) DRAWING
o True panel dimensions
o Location of repairs
o location of penetrations
ADDITIONAL POLYMER COMPONENTS
o Geotextiles
o Geonets
o Geogrids
o Pipe
VI-31
-------
SESSION VII - LINER COMPATIBILITY WITH WASTES
Robert Landreth
-------
GEOSYNTHETIC CHEMICAL RESISTANCE
TO
WASTES AND LEACHATES
GEOSYNTHETICS
OTHER
Flexible Membrane Uners
Geonets
- Geotextlles
- Plastic Pip*
Sands, Gravel, Clay
OBJECTIVE:
To ensure that the containment materials that
potentially come In contact with the waste*
or leachate are chemically resistant.
VII-l
-------
AREAS OF CONCERN:
* EXPOSURE CHAMBER
* REPRESENTATIVE LEACHATE
* TESTING OF COMPONENTS
* BLANKET APPROVAL
EXPOSURE CHAMBER
Representative Leachate
• Existing Facilities
• New Facilities
VII-2
-------
Representative Leachate
• Permit Applicants Guidance Manual
for LT, S, D Facilities
Chapter 5 pp. 15-17
Chapter 6 pp. 18-21
Chapter 8 pp. 13-16
METHOD 9090:
* LISTED IN SW-846 (9/86)
* GEOSYNTHET1C IMMERSED IN CHEMICAL
ENVIRONMENT FOR AT LEAST 120 DAYS
* TWO TEMPERATURES
* COMPARISON OF PHYSICAL PROPERTES AT
30 DAY INTERVALS
TESTS TO BE PERFORMED:
FML
HARDNESS
MELT INDEX
EXTRACTIBLES
VOLAmE LOSS
PEEL ADHESION
TEAR RESISTANCE
SPECIFIC GRAVITY
LOW TEMPERATURE
WATER ABSORPTION
PUNCTURE RESISTANCE
VII-3
-------
TESTS TO BE PERFORMED : (cont'd)
FML
DIMENSIONAL STABILITY
MODULUS OF ELASTICITY
BONDED SEAM STRENGTH
HYDROSTATIC RESISTANCE
CARBON BLACK DISPERSION
THICKNESS, LENGTH, WIDTH
TENSILE AT YIELD & BREAK
ENVIRONMENTAL STRESS CRACK
ELONGATION AT YIELD A BREAK
TESTS TO BE PERFORMED:
PIPING
STRENGTH TEST ASTM D2412, PARAGRAPH 6-9
REPORT AS PER ASTM D2412, PARAGRAPH 2
INCLUDING SECTION 11.1.7 AND 11.1.9
TEST TO BE PERFORMED
GEOTEXTILES/GEONETS
PUNCTURE
THICKNESS
PERMITTIVITY
TRANSMissivrnr
MASS/UNIT AREA
BURST STRENGTH
ABRASIVE RESISTANT
PERCENT OPEN AREA
ULTRAVIOLET RESISTIVITY
GRAB TENSILE/ELONGATION
VI I-4
-------
TEST TO BE PERFORMED: (cont'd)
GEOTEXTJLES/GEONETS
EQUIVALENT OPENING SIZE
HYDROSTATIC BURSTING STRENGTH
TEARING STRENGTH (TRAPEZOIDAL)
COMPRESSION BEHAVIOR/CRUSH STRENGTH
NOTE; ASTM-D35 COMMITTEE HAS BEEN DEVELOPING
PROCEDURES. THEY SHOULD BE CONSULTED
FOR LATEST INFORMATION.
IN PLACE TRANSMITT1VITY:
Geotextiles/Geonets
A 1.5x Maximum expected overburden
(Recommend 2-3x for creep, intrusion)
A Test apparatus similar to field conditions
A Age in leachate, test with water
A Test minimum of 100 hours
DRAINAGE MATERIAL (NATURAL):
* DEMONSTRATE NON-OISSOLVNQ OR FORM A
PRECIPITANT THAT WOULD CLOQ THE SYSTEM
* PERMEABILITY ASTM D2434
it BEARING RATIO ASTM D18S3
VII-5
-------
BLANKET APPROVALS
DATA ANALYSIS:
* REVIEWING FOR RATE OF CHANGE
* NEED EXPERT FOR REVIEW
* FLEX
VII-6
-------
SESSION VIII - LONG-TERM CONSIDERATIONS
Robert Koerner
-------
Session VIII - Long Term Considerations and Unknowns
(by R. M. Koerner)
1.0 Overview
1.1 Site Specific Conditions
1.2 Time Frames Required
1.3 Long Term Concerns
2.0 Flexible Membrane Liners (FML's)
2.1 Polymer Aging (Kinetics)
2.2 Degradation Processes (Physical/Chemical)
2.2.1 Oxidation
2.2.2 Ultraviolet
2.2.3 High Energy Radiation
2.2.4 Chemical - pH Effects
2.2.5 Chemical - Leachate Effects
2.2.6 Biological
2.2.7 Others
2.3 Stress Induced Mechanisms (Mechanical)
2.3.1 Creep and Stress Relaxation
2.3.2 Environmental Stress Crack
2.3.3 Environmental Stress Rupture - Sheet
2.3.4 Environmental Stress Rupture-Seams
2.4 Summary
3.0 Clay Liners
4.0 Leachate Collection Systems
4.1 Overview of Location and Types
4.2 Chemical Degradation
4.3 Leachate Withdrawal Frequency
4.4 Precipitate or Solids Clogging
4.5 Biological Clogging
4.5.1 Types
4.5.2 Likelihood of Occurrence
4.5.3 Avoidance/Remediation
4.6 Extrusion and Intrusion into LDR System
5.0 Cap/Closure System
5.1 Disturbance Concerns
5.2 Asthetics
VIII-l
-------
1.1 Site Specific Conditions
• geology/stratigraphy
• seismicity
• groundwater location
• groundwater quality
• population density
• size of facility
• leachate quantity and
quality (with time)
• nontechnical considerations
(social, political, economic)
1.2 Time Frames Required
heap leach pads 1 - 5 years
waste piles 5 -10 years
surface impoundments 5 - 25 years
solid waste landfills 30 -100 years
radioactive waste landfills... 100 -10,000 years
VIII-2
-------
1.3 Long-Term Concerns (Y = yes; N = no)
Mechanism
1. Movement of Subsoil
2. Subsidence of V\(aste
3. Aging
4. Degradation
5. Clogging
6. Disturbance
Cap
FML
N
Y
Y
Y
N
Y
Clay
N
Y
Y
N
N
Y
Cap - SWCR
Nat.
N
Y
Y
N
Y
Y
SYN
N
Y
Y
Y
Y
Y
P-FML
Y
N
Y
Y
N
N
LCR
Nat.
N
N
Y
N
Y
N
SYN
N
N
Y
Y
Y
N
Sec. Liner
FML
Y
N
Y
Y
N
N
Clay
Y
N
N
N
N
N
LDCR
Nat.
N
N
N
N
Y
N
SYN
N
N
Y
Y
Y
N
where:
FML = geomembrane liner
LCR = leachate collection and removal system
SWCR r surface water collection and removal system
Nat. = made from natural soil materials
Syn. '= made from synthetic polymeric materials
-------
2.1 Polymer Aging (Kinetics)
• equilibrium molecular structure exists for all
polymers when in isolation
• at this state there should be negligible aging
• best indicators are density "p" or perhaps
glass transition temperature "Tg"
• long term response is based on lab tests and
accelerated by high temperature
• we are not "in isolation", and degradation can
bring on aging
2.2 Various Degradation Processes (Physical/Chemical)
• separate phenomena
• no particular order
• interaction (synergism) not considered
• all involve chain scission
2.2.1 Oxidation Degradation
• major consideration
• occurs rapidly at temperatures » 200°F
• leads to loss of mechanical properties and embrittlement
• mechanism is understood
• heat liberates free radicals
• oxygen uptake occurs
• accelerated by hydroperoxides
• subsequent bond scission occurs
• hydrogens attached to tertiary carbons are most
vulnerable
• questionable (certainly very slow) at ambient
temperature
VIII-4
-------
2.2.2 Ultraviolet Degradation
• all polymers degrade (photooxidation) when exposed
to UV light
• most severe wavelength UV-B (315-380 nm)
• ASTM D4355 - Xenon Arc apparatus for assessment
• requires blocking agent, e.g., carbon black
• this only slows degradation
• avoid by covering with soil or waste
• approximate time frames to cover
FML's — 6 to 8 weeks
geonets — 3 to 6 weeks
geotextiles — 1 to 3 weeks
2.2.3 High Energy Radiation
• Radioactive waste only
• Gives off products of disintegration
• High energy levels which break molecular chains
• Serious concern for hi-level and transuranic waste
' Nominal concern for low level
(e.g., hospital waste, some industrial waste)
• Effect of long term (> 100 years) low level
exposure not known
2.2.4 Chemical (pH effects) Degradation
• all polymers swell in association with water (ph = 7)
• PVC =10%
1 PA 4 to 4.5%
• PP =3%
0.5 to 2.0%
0.4 to 0.8%
in very acid environments (pH < 3)
• PA is of concern
in very alkaline environments (pH > 12)
• PET is of concern
high temperatures accelerate the process
VIII-5
-------
2.2.5 Chemical (Leachate) Degradation
• EPA 9090 for FML incubation and test methods
• Assessment of subtile changes is difficult
• Very controversial topic; FLEX helps
• EPA 9090 generally stopped after 120 days
Field verification is helpful
• Butyl - 30 years
• PVC - 26 years
• CSPE - 20 years
• HDPE-10 years
But failures are generally not published
2.2.6 Biological Degradation
• microorganism must attach itself to polymer
• must find chain endings
• not likely for high molecular weight polymers
• plastlcizers and processing aides unknown
• laboratory tests cannot degrade resins
• field studies show no bio-degradation
• higher biological forms (termites, moles, etc.)
might be problem by scratching holes
• most FML's are quite tough
2.2.7 Other Degradation Processes
• thermal (requires very high temperatures)
• ozone (covering avoids)
• extraction via diffusion (plasticizers mainly)
• delamination (rarely a problem)
VIII-6
-------
2.3 Stress Induced Mechanisms (Mechanical)
• freeze-thaw (bury sufficiently deep)
• abrasion (not likely)
• creep (to be discussed)
• ESC (to be discussed)
2.3.1 Creep and Stress Relaxation (Mechanical)
• Requires FML to be stressed
o
cU
Can occur at anchor trenches, sumps, protrusions,
settlement locations, subsidence locations, folds,
creases, etc.
Key is to keep DR's high i.e.,
aact " °yfor semi-crystalline FML's
aact " °b for scrim reinforced FML's
aact " aallow tor nonreinforced thermoplastic FML's
2.3.2 Environmental Stress Crack
• only a potential problem with semicrystalline FML's
• ASTM D1693 - "Bent Strip Test" (over)
• A constant strain test stress which depends on
material, thickness, etc.
• Notched specimens immersed in surface
active reagent at 50°C (122°F)
• Proportion of total number that crack in a
given time are observed
• Most HOPE sheet is good in this test
VIU-7
-------
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SPECIMEN HOLDER
(B)
TEST
ASSE.-OLY
(C)
Details of ASTM D 1693 on "Environmental Stress-Cracking of Ethylene
Plastics"
VIII-8
-------
2.3.3 Environmental Stress Rupture - Sheet
• only a potential problem with semicrystalline FML's
• ASTM D2552 - "ESR Under Tensile Load"
• dogbone specimens under load, immersed in
surface active reagent at 50°C (122°F)
• results in elastic, plastic or cracked states
• commercial sheet is generally elastic
for a < 0.50 CTy and plastic for a > 0.50 crv
PINION ARRANGEMENT
2.3.4 Environmental Stress Rupture - Seams
• only a potential problem for semicrystalline FML's
• ASTM D2552 (mod) - "ESft Under Tensile Load"
• long dogbone specimens with constant width
cross section in narrow seamed region
• other conditions as noted before
• behavior should be as good as parent sheet
material
\
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u
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lo
V.
VIII-9
-------
2.4 Summary of Aging and Degradation Phenomena
• Current polymers are very stable
• EPA 9090 is good indicator of chemical behavior
• Underground environment eliminates most
degradation processes
• Biological degradation no problem
• High DR's avoid creep problems
• ESC resistance of sheet is very good
• ESC resistance of field seams is of concern
3.0 Clay Liners
• long history as liner material
• 10 year* data with leachate is available
and generally satisfactory
• full concentration organic solvents is of concern
• volume change and dessication may be of
concern (site specific)
• freeze-thaw is of concern if insufficient cover (cap only)
4.0 Leachate Collection Systems
4.1 Overview of Locations and Types
LCR on bottom - gravel plus pipe
• LCR on sides - geonet or geocomposite
• LDCR on bottom and sides - geonet
• Filter for LCR on sides -geotextile
• Filter for LCR on bottom - sand and/or geotexti.e
VIII-10
-------
4.2 Chemical Degradation
• Gravel and sands OK
• Concern for freshly crushed limestone
• EPA 9090 protocol for incubation of geosynthetics
• Test methods are not yet developed
• Recommended methods for testing
Test Type
thickness
mass/unit area
grab tensile
wide width tensile
puncture (pin)
puncture (CBR)
trapezoidal tear
burst
Geotextile
Y
Y
Y
Y
N
Y
Y
Y
Geonet
Y
Y
N
Y
N
Y
N
N
Geocomposite
Y
Y
N
N
N
Y
N
N
4.3 Leachate Withdrawal Frequency
• during filling - continuous removal depending
on rainfall/snowmelt
• after closure, see following
• very site specific
4.4 Precipitate or Solids Clogging
• Leachate composition (18 landfills)
• Total solids 0-59,200 mg/l
• Total dissolved solids 584 - 44,900 mg/l
• Total suspended solids 10 -700 mg/l
• Salts precipitating from high pH leachate
• Iron ocher (see biological clogging)
• Sulfides (see biological clogging)
• Carbonates (see biological clogging)
VIII-11
-------
4.5 Biological Clogging
4.5.1 Types
slime and sheath formation
• biomass formation
• ochering
• sulfide deposition
• carbonate deposition
4.5.2 Likelihood of Occurrence
• geocomposites least likely
• geonets 1 I
• gravel
• geotextile and sand most likely
4.5.3 Avoidance/Remediation
• high pressure water flush
• biocide flush
• time release surface biocide
• time release internal biocide
• must be considered in design stage
4.6 Extrusion and Intrusion into LDR System
• Clay extrusion through geotextile into geonet
(from composite primary liner)
• FML intrusion into geonet
(elastic and creep)
• Geotextile intrusion into geonet from composite
primary liner (elastic and creep)
• Key is to use high DR's on strength of all
geosynthetics
5.0 Cap/Closure System
5.1 Disturbance Concerns
• Erosion
rain, hail, snow, freere-thaw, wind
• Vegetation
grasses, shrubs, trees
• Burrowing or Soil Dwelling Animals
animals, reptiles, insects
• Sunlight
ultraviolet, ozone
• Human Activities
accidental, intentional
VI11-12
-------
5.2 Asthetics
Trash Mountain, or
New Jersey Meadowlands Concept
VIII-13
-------
SESSION IX - LEAK RESPONSE ACTION PLAN
Sarah Hokanson
-------
RESPONSE ACTION PLAN
FOR LEAKAGE IN
HAZARDOUS WASTE LANDFILLS
Sarah Hokanson
The Earth Technology Corporation
RESPONSE ACTION PLAN (RAP)
Need for RAP
• Even with good CQA, FMLs can leak:
-- Permeation (Intact FML)
-- Pinholes
-- A small tear, 1 per acre.
• Leakage rates through FMLs vary from <1 to >300
gpad
• If unchecked, leakage could increase and cause
increased hydraulic head over bottom liner.
RESPONSE ACTION PLAN
Proposed Rule for RAPs: May 29, 1987*
• Established triggers for RAPs.
- Action Leakage Rate (ALR)
- Rapid and Large Leakage (RLL)
• Defined the elements of a RAP
• Gave example of a RAP.
• Discussed the submittal/review process.
* Guidance on RAPs will be developed in 1989 or 1990,
RESPONSE ACTION PLAN
Discussion Topics
* Action Leakage Rate (ALR)
• Rapid and Large Leakage (RLL)
• RAP Submittal/Review Procedures
IX-l
-------
CALCULATED LEAKAGE RATES THROUGH
FML AND COMPOSITE LINERS
FML ALONE
Hydraulic Head, ft
0,1 1 10
Leakage Mechanism Leakage Rate, gpad
Permeation 0.001 0,1 10
Small Hole 30 100 300
Standard Hole 300 1,000 3,000
COMPOSITE LINER (GOOD CONTACT)
Hydraulic Head, ft
0.1 1 10
Leakage Mechanism Leakage Rate, gpad
Permeation 0.001 0.1 10
Small Hole 0.01 0.1 2
Standard Hole 0.01 0.2 3
Source: EPA, 1987
IX-2
-------
ACTION LEAKAGE RATE (ALR)
Concept of an ALR Trigger
• ALR triggers interaction between owner/operator
and EPA.
• ALR based primarily on leakage rate rather than
ieachate quality, because:
- Faster processing of data
-- Changes in leakage rate more indicative of
progressive changes in top liner condition
-- More indicative of severity of breach in FML.
Basis for the ALR
• Calculated leakage through a small FML defect
(1-2 mm dia.), assuming hydraulic head of 0.1 ft.
ACTION LEAKAGE RATE
EPA Proposed Rule
• ALR of 5 to 20 gpad
• Owner/operator allowed to use site-specific ALR value.
Determination of Whether ALR Has Been Exceeded
• Daily leakage rates can vary 10 to 20 percent or more,
even without precipitation.
• Much higher leakage rates may be recorded over short
periods after rainfall.
• Thus, EPA proposed the following procedure to
determine if ALR has been exceeded:
-- If daily leakage rates •< 50 gpad,
average the readings over 30 days.
RAPID AND LARGE LEAKAGE (RLL)
Definition of RLL
• RLL > maximum design leakage (i.e., fluid head >
thickness of the LCRS drainage medium)
Significance of Leakages Exceeding RLL
• Leakage rates > RLL significantly increase potential
for bottom liner failure.
• Such leakage can lead to catastrophic failure of the
double liner system.
IX-3
-------
RAPID AND LARGE LEAKAGE
Proposed Rule
• EPA requires owner/operators to calculate RLL
value, based on the design of the LCRS.
• EPA requires owner/operators to submit a RAP for
such leakage prior to receipt of wastes,
RAPID AND LARGE LEAKAGE
Calculating RLL
Assuming uniform flow:
h = (Qd/B)/(kdtanp) (1)
where:
h = hydraulic head (m)
0^ = flow rate in drainage layer (m3/s)
B = width of drainage layer perpendicular to flow (m)
k^ = hydraulic conductivity of drainage layer (m/s)
P = slope of drainage layer.
Source: EPA, 1987
RAPID AND LARGE LEAKAGE
Calculation of RLL (continued)
However, lor RLL leakage rates, the width of (low (wetted area) is not
equal to B. but some unknown width b.
;- Leak
Flow
Direction
High Edge
(upgradient)
Lower Edge
(downgradient)
Collector
Pipe
Plan view of a leak detection system with a
large leak flowing over a width b.
Source: EPA. 1987
IX-4
-------
RAPID AND LARGE LEAKAGE (continued)
Calculating RLL
If N is frequency of leaks:
q = NQ (2)
where:
q = leakage rate per unit area (m/s)
N = leak frequency (rrr2)
Q = leakage rate for one leak (m3/s)
Combining Equations 1 and 2, substituting b for B,
h = [q/(Nb)]/(kdtan(3)
h = q/(Nbkdtanp) (3)
Source: EPA, 1987
RAPID AND LARGE LEAKAGE (continued)
Calculating RLL
Typical design case of 1 hole per 1 acre (under good
CQA): N = 1/4,000 m2.
Substituting this value into
equation 3:
h = 4,000 q/(bkdtan(3) (4)
or
h = 4.6 x 10-8q/(bkdtan(3) (5)
where q has units of Ltd.
For 2% slope, tanp = 0,02, and kd = 10~2 m/s, Equation 5
becomes:
h = 2.3 x 10-" q/b (6)
for h(m), q(Ltd), and b(m).
RANGES OF RLL VALUES AS A FUNCTION OF
HYDRAULIC HEAD AND WIDTHS (b)
Leakage Rate, gpad
100 1,000 2,000 10,000
Width (b), ft Hydraulic Head on Bottom Liner, ft
3.3
5
6.6
0.08
0.05
0.03
0.75
0.5
0.3
1.5
1
0.7
7,5
5
3.6
RAPID AND LARGE LEAKAGE
Summary
• Therefore, RLL for granular drainage materials is
approx. 2,000 gpad. although value is highly
dependent on leak size.
• Future guidance will address this issue.
IX-5
-------
RESPONSE ACTION PLANS (RAP)
Elements of RAP
• General description of unit
• Description of waste constituents
• Description of all events that may cause leakage
• Discussion of factors affecting amounts of leakage
entering LCRS
• Design and operational mechanisms to prevent leakage
of hazardous constituents
• Assessment of effectiveness of possible response
actions
RESPONSE ACTION PLAN
Sources of Information for the RAP
• Part B Permit Application
• Operational Records and Practices
• Leachate Analysis
• CQA Report
RESPONSE ACTION PLAN
Sources of Liquids Other Than Leachate
• Rainwater trapped in the leak detection drainage layer
during construction
• Moisture from compacted soil components of composite
top liner
• Groundwater permeation through bottom liner
RESPONSE ACTION PLAN
Development of RAPs
• RAPs must be developed for two basic ranges:
1. Leakage rates > RLL
2, ALR < leakage rate < RLL.
• RAP 1 must be submitted prior to receipt of wastes.
• RAP 2 may be submitted with RAP 1, or after ALR is
exceeded.
IX-6
-------
RESPONSE ACTION PLAN
Response Actions for Leakage Rates > RLL
• Stop receiving wastes and close unit (or part of unit).
• Repair the leak(s) (or retrofit top liner).
• Institute operational changes to reduce leakage to
< RLL,
RESPONSE ACTION PLAN
Response Actions for Leakage Rate < RLL
• Develop leakage bands.
• More specific response actions from assessment of
source of liquids
• Leachate quality analysis (currently required in proposed
rule)
• Response actions for RLL leakage may also apply.
SAMPLE RAP FOR LEAKAGE < RLL
ALR = 20 gpad and RLL = 2,500 gpad:
Leakage
Band Generic Response Action
20 Notify RA and identify sources of
liquids.
20-250 Increase pumping and analyze liquids
in sump.
250-2,500 Implement operational changes,
RESPONSE ACTION PLAN
RAP Submittal Requirements (Proposed)
Permitted
• For newly permitted, RAP for RLL submitted along with
Part B.
• For existing, RAP for RLL submitted as a request for
permit modification,
Interim Status
• RAP for RLL submitted 120 days prior to receipt of
waste.
IX-7
-------
RESPONSE ACTION PLAN
RAP Submittal Requirements (Proposed)
• If RAP for > ALR not submitted prior to waste receipt,
submit RAP within 90 days of determination that ALR
has been exceeded.
• The RA's approval is required before RAP can be
implemented.
RESPONSE ACTION PLAN
Reporting Requirement (Proposed)
Owner/operator must notify the RA within 7 days when ALR
has been exceeded and must:
• Implement RAP (if submitted)
• Collect and remove liquids from sump
• Sample liquids for leachate quality parameters.
RESPONSE ACTION PLAN (continued)
Reporting Requirement (Proposed)
For RLL leakages, owner/operator must notify the RA within
7 days of detecting the leakage and must:
• Immediately implement the RAP
• Sample liquids for leachate quality parameters.
Owner/operator must report progress of RAP within 60
days of implementation. Significant increase in leakage rate
must also be reported.
SUMMARY OF PROPOSED REGULATIONS ON RAPS
ALR
• Proposed ALR between 5 and 20 gpad
• EPA will allow a site-specific ALR.
RLL
• To be determined based on design
IX-8
-------
SUMMARY OF PROPOSED REGULATIONS ON RAPS
RAP
• Elements include description of:
- Unit
-- Waste
-- Possible causes of leakage
-- Design and operational factors affecting leakage
into LCRS
-- Mechanisms to prevent hazardous constituent
migration
-- Effectiveness/feasibility of response action,
• Consider other sources of liquids.
SUMMARY OF PROPOSED REGULATIONS ON RAPS
(continued)
RAP
• Upon exceeding the ALR on RLL, owner/operator
must:
- Notify RA
-- Implement RAP (if approved)
-- Submit RAP (if not submitted)
-- Collect and remove liquids
-- Sample for leachate quality indicators,
• Response Actions can range from termination of
operations and closure (large leakages) to increased
pumping and monitoring (small leakages).
IX-9
-------
APPENDIX A
-------
REFERENCES
Acar, Y.B., and A. Ghosn. 1986. Role of Activity in Hydraulic Conductivity
of Compacted Soils Permeated with Acetone. Proceedings, International
Symposium on Environmental Geotechnology, Allentown, Pennsylvania, pp.
403-412.
Acar, Y.B., Hamidon, A., Field, S.D., and L. Scott. 1986. The Effect of
Organic Fluids on Hydraulic Conductivity of Compacted Kaolinite. ASTM STP
874, pp. 171-187.
Addy, S., and G.N. Richardson. 1988. Upgrading Industrial UST Systems.
Twentieth Mid-Atlantic Industrial Waste Conference, Howard University.
Ainsworth, J.B., and A.O. Ojeshina. 1984. Specify Containment Liners.
Hydrocarbon Processing.
Anderson, D.C. 1982. Does Landfill Leachate Make Clay Liners More Permeable?
Civil Engineering, Vol. 52, No. 9, pp. 66-69.
Auvinet, G., and J. Espinosa. 1981. Impermeabilities of a 300-Hectare Cooling
Pond. ASTM STP 746, pp. 151-167.
Bass, J. 1986. Avoiding Failure of Leachate Collection and Cap Drainage
Systems. U.S. EPA, Hazardous Waste Engineering Research Laboratory,
Cincinnati, Ohio.
Bass, J.M. et al. 1984. Assessment of Synthetic Membrane Successes and
Failures at Waste Storage and Disposal Sites. U.S. EPA, Cincinnati, Ohio.
Bouwer, H. 1966. Rapid Field Measurement of Air Entry Value and Hydraulic
Conductivity of Soil as Significant Parameters in Flow System Analysis.
Water Resources Research, Vol. 2, No.4, pp. 729-738.
Bowders, J.J. 1985. The Influence of Various Concentrations of Organic
Liquids on the Hydraulic Conductivity of Compacted Clay. Dissertation,
University of Texas at Austin, 219 pp.
Bowders, J.J., Daniel, D.E., Broderick, G.P., and H.M. Liljestrand. 1986.
Methods for Testing the Compatibility of Clay Liners with Landfill
Leachate. ASTM STP 886, pp. 233-250.
Boynton, S.S., and D.E. Daniel. 1985. Hydraulic Conductivity Tests on
Compacted Clay. Journal of Geotechnical Engineering, Vol. 11, 1 No.4, pp.
465-478.
Brown, K.W., Green, J.W., and J.C. Thomas. 1983. The Influence of Selected
Organic Liquids on the Permeability of Clay Liners. EPA 600/9-83-018, pp.
114-125.
A-l
-------
Calhoun, C.C., Jr. 1972. Development of Design Criteria and Acceptance
Specifications for Plastic Filter Cloth. Technical Report F-72-7. U.S.
Army Engineer Waterways Experiment Station, vicksburg, Mississippi.
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A-2
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A-4
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A-5
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Schatch, J.R. 1981. Improved Analytical Methods for the Design of Leachate
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tion of Landfill Performance (HELP) Model: Vol. II, Documentation for
Verison I. EPA/530/SW-84-010, Municipal Environmental Research
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Hydrologic Evaluation of Landfill Performance (HELP) Model: Vol. I,
User's Guide for Version I. EPA/530-84-009, Municipal Environmental
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Landfills and Surface Impoundments. Municipal Environmental Research
Laboratory, U.S. EPA, Cincinnati, Ohio.
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International Conference on Geomembranes, Denver, Colorado.
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Construction of Disposal Facilities. EPA-600/2-84-040, 181 pp.
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Geomembranes With and Without Friction. Proceeding of International
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Water Monitoring Review. Vol. 4, No. 4, pp. 131-138.
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625/6-82-006, U.S. EPA, Cincinnati, Ohio.
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of Solid Waste and Emergency Response, Washington, DC, SW-870.
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85/002. U.S. EPA, Cincinnati, Ohio.
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U.S. EPA. 1985c. Draft Minimum Technology Guidance on Double Liner Systems
for Landfills and Surface Impoundments — Design, Construction, and
Operation. EPA/530-SW-84-014.
U.S. EPA. 1985d. Guidance on implementation of the Minimum Technological
'Requirements of HSWA of 1984, Respecting Liners, and Leachate Collection
Systems. EPA/530-SW-85-012.
U.S. EPA. 1985e. Hazardous Waste Management Systems; Proposed Codification
Rule. Federal Register, Vol. 50, No. 135, 28702-28755.
U.S. EPA. 1985f. Minimum Technology Guidance in Double-Liner Systems for
Landfills and Surface Impoundments - Design, Construction, and Operation.
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Disposal Facilities. EPA-530-SW-85-021, U.S. EPA, Cincinnati, Ohio.
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2-85/-002, Hazardous, U.S. EPA, Cincinnati, Ohio.
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at Hazardous Waste Sites. Hazardous Waste Engineering Research
Laboratory, Cincinnati, Ohio, EPA/600/2-86/085.
U.S. EPA. 1986d. Hazardous Waste Management Systems; Proposed Codification
Rule. Federal Register, Vol. 51, No. 60, 10706-10723.
U.S. EPA. 1986e. Hazardous Waste Surface impoundments (Draft). Prepared by
K.W. Brown and Associates for U.S. EPA, Cincinnati, Ohio.
U.S. EPA. 1986f. Technical Guidance Document: Construction Quality Assurance
for Hazardous Waste Land Disposal Facilities. EPA/530-SW-86-031.
U.S. EPA. 1987a. Background Document on Bottom Liner Performance in Double-
Lined Landfills and Surface Impoundments. EPA/530-SW-87-013.
U.S. EPA. 1987b. Guidance Manual for Prediction and Mitigation of
Settlement Damage to Covers of Hazardous Waste Landfills (Draft). U.S.
EPA, Cincinnati, Ohio.
U.S. EPA. 1987c. Hazardous Waste Management Systems; Minimum Technology
Requirements: Notice of Availability of information and Request for
Comments. Federal Register, Vol. 52, No. 74, 12566—12575.
U.S. EPA. 1987d. Background Document on Proposed Liner and Leak Detection
Rule. EPA/530-SW-87-015.
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Disposal Units: Notice of Proposed Rulemaking. Federal Register, Vol.
52, No. 103, 20218-20311.
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U S. EPA. 1988. Design, Construction, and Evaluation of Clay Liners for
'waste Management Facilities. EPA/530-SW-86-007f. Available Late Summe
1988.
0259T
A-ll
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APPENDIX B
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Federal Register / Vol. 52. No. 74 / Friday, April 17, 1987 / Proposed R.
York's monthly vacuum-based leak
check procedure did not satisfy the
statutory criterion of being in
accordance with good engineering
practices and was not equivalent to the
quality control procedures specified in
§ 85.2217. However, New York agreed
that these error rates were undesirable
and has changed its procedures to
include weekly probe/port comparison
leak checks, effective June 3,1985. This
change is consistent with the procedure
specified in 5 85,2217(d).
D. EPA'* Preliminary Determination
The quality control procedures in
§ 85.2217 of the warranty short test
regulations have been determined by the
Administrator to meet the statutory
criteria of being readily available, in
accordance with good engineering
practices, and resulting in the short testa
being reasonably capable of being
correlated with the FTP (see 45 FR
34802). In the case of New York's
alternative quality control procedures,
since they are currently being used, it is
clear that thes
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Federal Register / Vol. 52. No. 74 / Friday, April 17. 1987 / Proposed Rules
12567
address and telephone number Listed
below:
Draft Minimum Technology Guidance
on Single Liner Systems for Landfills,
Surface Impoundments, and Waste
Piles—Design. Construction, and
Operation (EPA/530-SW-65-013);
Draft Minimum Technology Guidance
on Double Liner Systems for Landfills
and Surface Impoundments—Design,
Construction, and Operation (EPA/
530-SW-85-OH); and
Background Document on Bottom liner
Performance in Double-Lined
Landfills and Surface Impoundments
(EPA/530-SW-87-013).
In addition, copies of the background
document are available for review in the
Office of Solid Waste (OSW) docket
room.
FOR FURTHER INFOfUUTtOM COHTACT:
For general information, call the RCRA
Hotline, at (800) 424-9346 (toll free] or
(202) 382-3000. For technical
information, contact Kenneth Skahn.
Office of Solid Waste (WH-565E). U,&
Environmental Protection Agency, 401 M
Sreeet. SW. Washington, DC 20460. (202)
382-1654.
SUPPLEMENT AMY IMFOftMATtOM:
Background
The Hazardous and Solid Waste
Amendments (HSWA) of 1984. require
that certain landfills and surface
impoundments must have two or more
liners and a leachate collection system.
Specifically, section 3004(o){l)(A) of
RCRA. as amended by HSWA, requires
new landfills or surface impoundments,
each new landfill or surface
impoundment unit at existing facilities,
and each lateral expansion or
replacement of a landfill or surface
impoundment unit at existing facilities
(for which a permit is received after
November a 1984) to have at least two
liners and a leachate collection system
above (for landfills) and between such
liners (i.e., double-liner minimum
technology requirements). Section
30l5(b) of RCRA extends the double-
liner and leachata coUectioB system
requirements of 30M(o)(l)(A) to new
units, replacement unit* and lateral
expansion of existing units at Interim
status landfills and surface
impoundments that are within the waste
management area identified in the permit
application with respect to wastes
received beginning May 8,1985.
Therefore, certain landfills or surface
impoundments must meet the double-
liner minimum technological
requirements of section 3004(o)(l)(A).
unless they qualify for an exemption
under sections 3004(o), 3005(j). Under
section 3004(o)(5)(A), EPA is required to
issue regulations or technical guidance
by November 8,1986, implementing the
requirements of section 3004(o)(l)(A).
In additioa section 3015(a) of RCRA
requires new units, replacements and
lateral expansions of interim status
waste piles to comply with the single
liner and leachate collection and
removal system requirements with
respect to waste received beginning
May 8,1985. The requirements for waste
pile units in 40 CFR 264.251(a) and
265.254 and the draft technical guidance
for single liners cited above, provide
standards and guidelines for design.
construction, and operation of these
single-lined units.
Until EPA issues new regulations or
guidance on liners and leachate
collection systems in accordance with
section 3004(o)(5). double liner systems
may be designed, constructed, and
installed according to the interim
statutory provisions of RCRA, section
3004(o)(5)(B), that were codified on July
15,1985 (50 FR 28702), in 40 CFR
264.221(c), 264.301(c), 265.221(a). and
265.301(a). These interim standards
require that the top and bottom liners be
designed, operated, and constructed of
materials to prevent hazardous
constituent migration during the active
life and postdosure care period for the
unit. In the preamble to the July 15,1985,
regulation (50 FR 28702), the Agency
states that the top liner standard can be
met by a flexible membrane liner (FML).
According to RCRA section
3004(o)(5)(B), the bottom Lmer must be
constructed of at least three feet of
recompacted soil or other natural
materials with a permeability of no
more than 1 x 10"' on/sec
In addition to double liner and
leachate collection system requirements.
the minimum technological requirements
under section 3004(o)(4) of RCRA, as
amended by HSWA, call for the
utilization of an approved leak detection
system (LDS) for new landfills, surface
impoundments, waste piles,
underground tanks, and land treatment
units. This LDS must be able to detect
leakage of hazardous constituents at the
earliest practicable time. Section
3004(o)(4){A) requires EPA to
promulgate standards for the LDS no
later than May a 1987.
On March 28,1986, EPA proposed
amendments to the interim statutory
provisions for double Liners under the
authority of section 3004{o)(5)(A). This
proposal set forth alternative
performance standards for double liner
systems (51 FR 10707-10711).
Under the first alternative, the
proposal requires a liner system to
include both top and bottom liners
designed, operated, and constructed of
materials to prevent hazardous
constituent migration during the active
life and post-closure care period (40 CFR
Part 264^21(c)). To meet this standard,
the top liner must be an FML (51 FR
10709). The proposal provides that the
bottom liner performance standard may
be met by a liner constructed of at least
a 3 foot layer of compacted soil or other
natural materials with a maximum
hydraulic conductivity of no more than 1
x ID"' cm/sec (40 CFR 264.221(c)).
Under the second alternative
proposed on March 28.1986, the liner
system must include a top liner meeting
the same performance standard that is
described for the first alternative. The
bottom liner must consist of two
components that are intended to
function as one liner. The upper
component of the composite liner must
be designed, operated, and constructed
of materials to prevent hazardous
constituent migration into this
component during the active life and
post-closure care period. In the
preamble to the proposal, we state that
the top liner must be an FML (51 FR
10709). The lower component must be
designed, operated, and constructed of
materials to minimize hazardous
constituent migration through the upper
component if a breach in the upper
component occurs before the end of the
post-closure care period. The lower
component must be constructed of
compacted soil material with a
hydraulic conductivity of no more than 1
x 10~7 cm/sec. In the preamble, we note
that the composite liner should consist
of a FML and a compacted soil
component at least 3 feet (90 cm) thick
(51 FR 10710).
Based on date available at the time of
the proposal, EPA believed that both
these systems could meet the overall
double liner system goal of preventing
hazardous constituent migration out of
the unit during the active life and post-
closure care period for the facility.
However, in the preamble EPA
expressed some concern about the long-
term performance of the compacted soil
bottom liner (51 FR 10709), noting that if
leachate migrates through a breach in
the top FML liner, the leachate may be
trapped in the compacted low
permeability soil liner rather than be
collected and removed in the leachate
collection system between the liners.
EPA will soon be proposing
regulations for an approved leak
detection system (LDS) at newly
constructed units to meet the statutory
provisions in section 3004(o)(4)(A).
EPA's current position is that the
leachate collection and removal system
(LCRS) proposed on March 28, 1986
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12568
Federal Register / Vol. 52, No. 74 / Friday, April 17, 1987 / Proposed F .s
(with some technical modifications) will
serve as the LDS for newly constructed
landfill and surface impoundment units.
On March 28,1986. the Agency proposed
to require the LCRS between the liners
to be designed, constructed, maintained,
and operated to detect, collect and
remove liquids that leak through any
area of the top liner during the active
life and post-closure care period (40 CFR
Part 264.221(c)). EPA plans to propose
LDS regulations in the near future.
These regulations will modify the
proposed LCRS by proposing additional
specific design standards requiring a
minimum bottom slope, a minimum
drainage layer hydraulic conductivity
and transmissivity, and a sump of
appropriate size to collect and remove
liquids efficiently. Additionally, under
the imminent LDS proposal the leachate
detection, collection, and removal
system (LDCRS) between the liners must
meet specified performance standards
for leak detection. It must be able to
detect a specified leakage within a
certain time period and to collect and
remove the liquids rapidly to minimize
the hydraulic head on the bottom liner.
In the course of developing these
proposed regulations we have collected
new data. As discussed more fully
below, this data indicates that
compacted soil bottom liners will not
detect and collect leaks as efficiently as
composite bottom liners.
EPA continues to believe that liners
are best used to facilitate the collection
and removal of leachate. This view of
liners is consistent with one of the
fundamental elements of the liquids
management strategy—to maximize the
collection and removal of leachate from
landfills, surface impoundments, and
waste piles. The overall objective of
EPA's liquids management strategy is
for hazardous waste management units
to be designed both to minimize the
amount of leachate generated and to
maximize the amount of leachate
collected and removed from the unit. As
landfills and surface impoundments
cannot currently be designed,
constructed, or operated to completely
prevent leachate generation, emphasis
must be placed on maximizing the
collection and removal of the leachate
from the unit. Therefore, the extent to
which the proposed botton liner systems
enhance or detract from the leachate
detection, collection, and removal
capabilities of the LDCRS was studied
by EPA.
A'eiv Data
The Agency is reviewing data that are
currently available from modeling
efforts, actual performance and
technical engineering analyses that
compare the performance of these two
bottom liners with respect to the
following parameters:
• Leachate collection efficiency;
• Leak detection capability; and
• Leakage, both into and out of, the
bottom liner.
EPA believes that any one of these
factors will significantly influence the
performance of the bottom liner and,
therefore, may influence EPA's final
decision concerning the composition of
the bottom liner.
Today, EPA is making this
information available for public
comment. The data are presented and
discussed in detail in a background
document for this notice and will be
considered along with other relevant
information provided by the public in
the development of the final double liner
rule. The background document is
entitled, "Background Document on
Bottom Liner Performance in Double-
Lined Landfills and Surface
Impoundments."
1. Background
Compacted soil liners have long been
used as barriers and foundations in
traditional civil engineering structures,
such as dams, canals, and highways.
They, therefore, have a long record of
strength and durability that allows them
to be used in these ways. However, as
porous and disaggregated materials,
soils are not impervious. In the case of
double-lined waste management units,
gravitational and capillary forces
present in an unsarurated. low
permeability soil liner will allow some
leakage through the top liner to be
absorbed into the bottom liner before it
can be detected, collected, and removed
by the LDCRS between the liners. Once
trapped in the liner, the hazardous
waste leachate will most likely migrate
through the liner and into the
environment.
Filed compacted, low permeability
soils are subject to nonuniform
hydraulic properties across and through
the linter, even with extensive
compactive and mixing effort and
moisture monitoring. Accordingly, a
compacted soil liner may contain
defects that increase the local effective
hydraulic conductivity and, hence,
detrimentally affect the liner's
performance.
In a compacted soil liner the thickness
will affect the time that liquids will
break through the bottom of the liner
and enter the surrounding environment,
but it will not affect leachate collection
and removal efficiency, leak detection
sensitivity, and total leakage out of the
unit. These parameters are mainly
controlled by the effective hydraulic
conductivity of the liner system.
Therefore, while thicker liners may be
able to satisfy the "prevent migration"
clause through the post-closure care
period, they will not perform as
effectively as a more impervious liner
system, such as a FML, with respect to
the three factors cited above.
The use of a flexible membrane as a
liner significantly improves the leachate
collection efficiency and leak detection
sensitivity of the system. FML's consist
of interlocking synthetic polymers and
thus are significantly more watertight
than granular materials, such as soils.
There is still an element of vapor
diffusion, or permeation, that allows
liquid to migrate though a perfectly
intact FML Nevertheless, the amount of
fluid migration through the liner is
extremely small and is estimated to be
comparable to that produced by a
porous materials with a hydraulic
conductivity in the range of 1 x 10"12
cm/sec. This factor alone implies a far
greater performance capability of FML's
with respect to leachate collection
efficiency, as well as leak detection
sensitivity.
However, even with good construction
quality assurance, a FML may contain
defects that increase the local effective
hydraulic conductivity and, hence, have
a detrimental affect on the liner's
performance. Even under a good
construction quality assurance program,
FML's may have up to 1 or 2 small holes
per acre of liner, based on engineering
analysis of the current technology.
On the other hand, a composite liner
consisting of a FML upper component
and compacted low permeability soil
lower component has several
advantages and combines the strengths
and capabilities of both materials to
maximize leachate detection, collection,
and removal from the unit. The FML
upper component greatly improves
leachate collection and removal
efficiency and leak detection sensitivity
of the LDCRS. In addition, the soil
component minimizes the migration of
liquids that leak through holes in the
FML and provide some attenuation of
leakage. As discussed more specifically
below, EPA's analysis shows that the
composite bottom liner system would
provide better leak detection sensitivity
and leachate collection and removal
efficiency than a compacted low
permeability soil. It would also
significantly reduce the amount of
leakage into the bottom liner and out of
the unit over time as a result of
increased leachate collection and
removal efficiency. Therefore, a well
constructed, installed, and operated
composite liner is expected to minimise
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Federal Register / Vol. 52, No. 74 / Friday, April 17, 1987 / Proposed Rules
12569
hazardous constituent migration out of
the unit by maximizing leachate
collection and removal.
2. Engineering Analysis of Performance
Data
In order to analyze the performance
capabilities of the two bottom liner
systems, the Agency reviewed available
performance data for compacted soil
and flexible membrane liners from
actual landfills and surface
impoundments. (Actual performance
data on composite bottom lines does not
exist at this time.) The review of such
data indicates that as a general matter,
compacted soil liners do not have
uniform hydraulic properties across and
through the liner. FMLs, on the other
hand, possess uniform hydraulic
properties. The range of actual
performance data for compacted soil
and flexible membrane liners was used
in the Agency's modeling analysis to
provide an understanding of the leak
detection sensitivity and leachate
collection efficiency of the bottom liners.
(See section 3 below.) The background
document more fully addresses the
performance capabilities of the two
bottom liner systems.
In addition, EPA recently conducted a
review of applications submitted for
RCRA hazardous waste facility permits
since November 8,19B4, to determine
the type bottom liner selected fnr
installation at new landfills and surface
impoundments. Of some 183 units for
which permit applications were
submitted as of February 1987, only
seven units were to b« constructed with
compacted low permeability soil bottom
liners. The vast majority of owners or
operators selected the composite bottom
liner rather than a compacted low-
permeability soil liner. Many owners or
operators have also indicated that they
plan to use a composite liner for the top
liner as well.
3. Analytical Data
Because only limited field data exist,
analytical and numerical modeling
approaches have been developed and
used by EPA to evaluate the
performance capabilities of the two
bottom liners at a typical landfill or
surface impoundment unit.
Three modeling approaches were used
to evaluate leachate collection
efficiency, leak detection sensitivity,
and leakage into and out of the bottom
liner:
• steady-state, saturated, 1-
dimensional flow;
• transient, unsaturated, 1-
dimensional flow; and
• transient, unsaturated, 2-
dimensional flow.
These approaches reflect three
different levels of analysis for
evaluating the performance of the
bottom liner. The results from each
analysis were compared and in some
cases aggregated in order to determine
the representative values for leachate
collection efficiency, leak detection
sensitivity and migration into and out of
the bottom liner. A detailed discussion
of each modeling effort is presented in
the background document. Figures
presented in this notice are derived from
the modeling efforts described in the
background document. Today's notice
does not contain a complete discussion
of the applications of each approach to
each performance parameter, such
discussion is. however, set forth in the
background document.
The detection sensitivity is the
smallest leakage rate through the top
FML that can be detected in the LDCRS
sump. For the compacted low
permeability soil liner at 1 x 10"' cm/
sec, the smallest leakage rate detected is
about 80-100 gallons per acre per day
(gpad) with a uniformly leaking FML top
liner, based on the 1-dimensional
saturated flow calculations (Figure 1).
The actual capability of a compacted
soil liner is site-specific and will depend
on many factors (e.g., location of the
leak, effective hydraulic conductivity of
the liner, and the design of the LDCRS
between the liners). However, as a
general matter a bottom liner of
compacted soil with a hydraulic
conductivity value of 1 x 10"'cm/sec
will perform significantly worse. For a
composite liner, the LDCRS can detect
leakage rates several orders of
magnitude smaller than 80 gpad, i.e.. 1
gpad. Even with a few holes in the FML
component, the composite liner still
performs much better than compacted
soil liners with respect to leak detection
senstitivity.
BIUJNO CODE (MO-50-M
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12570
Federal Register / Vol. 52. No. 74 / Friday, April 17, 1987 / Proposed Rules
LEAK DETECTION SENSITIVITY
1,000
Minimum Detectable
Leakage Rate
Through Top Liner
(GaUAcre/Day)
Compacted Soil
K • 1x1 (Hem/sec
TYPE OF BOTTOM LINER
Figure 1. Comparison of leak detection sensitivity for compacted soil and composite bottom liners.
•IUINC CODE (MO-50-C
B-5
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Federal Register / Vol. 52. No. 74 / Friday, April 17. 1987 / Proposed Rules
12371
The leachate collection efficiency is
the maximum possible leakage that can
be collected in the LDCRS sump divided
by the total leakage entering the LDCRS
through the liner. Figure 2 illustrates the
relative collection efficiencies of the
composite and compacted low
permeability soil liner systems assuming
uniform top liner leakage and steady-
state. 1-dimensional flow. Both systems
have greater than 90 percent collection
efficiency at very large leakage rates
(greater than 1000 gpad); at smaller
leakage rates that EPA believes are
more representative of current
technology and operating practices at
landfills and surface impoundments
(e.g., 10-100 gpad), the compacted low
permeability soil liners have near zero
percent efficiencies while the composite
liner has near 100% efficiency. Figure 2
also demonstrates the siginh'cant
reduction in collection efficiency with
an increase in hydraulic conductivity for
the compacted low permeability soil
liner. Increasing the number of defects
(holes) the FML component of the
composite liner reduces the collection
efficiency only slightly. Calculated
cumulative leachate collection
efficiencies over 10 years at a constant
leakage rate of 100 gpad (e.g., rates that
can be expected to be observed in
surface impoundment failures given the
large volume and depth of liquid
present) indicate that (1) composite
liners achieve a much greater leakage
collection efficiency than compacted
soil bottom liners, and (2) for compacted
soil bottom liners an increase in
hydraulic conductivity of the soils (to l
x 10'* cm/sec) produces a significant
decrease in collection efficiency.
MUJNO COOC M40-SO-*
B-6
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12S72
Federal Register / Vol. 52. No. 74 / Friday. April 17, 1987 / Proposed Rule*
LEACHATE COLLECTION EFFICIENCY
Composite (intact)
LEACHATE
COLLECTION
EFFICIENCY
100
50
Composite with
Small FML hole
Compacted Soil
K • 1x10-7 cm/sec
I
Compacted Soil
K • 1 x10-« cm/sec
I
1 10 100 1,000 10,000
TOP UNER LEAKAGE RATE (Gal./Acre/Day)
Figure 2. Comparison of leachate collection efficiencies for compacted soil and composite
bottom liners.
BILLING COM ISM-M-C
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Federal Register / Vol. 52. No. 74 / Friday, April 17, 1987 / Proposed Rules 12Z73
Leakage out of the unit refers to 1 x 10'' cm/sec, as opposed to Based on these data, the difference ,=.
leakage that passes into and through the composite liners as shown in Figure 3. performance is significant. The other
bottom liner. As illustrated in Figure 3, Calculated results from the computer important trend noted in evaluating the
composite liners have a much lower simulations indicate that the composite data is that compacted low permeabihiy
potential to allow leachate to migrate bottom liner performs conistently better soil lines with effective hydraulic
into the bottom liner. On a cumulative than compacted low permeability soils conductivities greater than 1 x 10"7
basis over 10 years, leakage into the with respect to maximizing leachate cm/sec perform significantly worse.
bottom liner is higher for compacted detection, collection, and removal and SILUNG cooc IMO-M-M
soils with a hydraulic conductivity of minimizing migration out of the unit.
B-8
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12574
Federal Register / VoL 52, No. 74 / Friday, April 17, 1987 / Proposed Rules
CUMULATIVE LEAKAGE INTO THE BOTTOM LINER
OVER TEN YEARS
200,000
150,000
CUMULATIVE
1EAKAGE INTO THE
BOTTOM UNER 100,000
(Cal./Acre)
50,000
160.000
Compacted Soil
K • 1x10-f cm/sec
Composite
large tear (10 ft.)
70
TYPE OF BOTTOM LINER
figure J. Cumulative leakage into the bottom liner over 10 years for a side wall top liner leak at SO
gal ./acre/day.
1IUINO COM fMO-M-C
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Federal Register / Vol. 52, No. 74 / Friday, April 17. 1987 / Proposed Rules
12575
4. Conclusions Based on New Data
The information collected and
included in the background document
argues strongly that the composite
bottom liner with the FML upper
component and compacted low-
permeability soil lower component will
significantly enhance the leachate
collection and removal efficiency and
the leakage detection capability of the
LDCRS. The composite liner best meets
the goals of preventing migration out of
the unit and detecting the leak at the
earlist practicable time. It is also more
effective in meeting the goal of the
liquids management strategy for
maximizing leachate collection and
removal.
Minimum Technology Guidance
The draft technical guidance
documents noticed today are second
drafts resulting from comments
submitted on the first drafts that were
sent to state agencies, environmental
groups, trade associations and the
regulated community. These second
drafts are significantly different from the
original drafts as a result of the
comments received. EPA solicits
comments from the general public on
these revised drafts of technical
guidance for single and double-liner
systems.
The draft double liner guidance, EPA/
530-SW-85-014, applies to new units
and lateral expansions and
replacements of existing units at
hazardous waste landfills and surface
impoundments. The two double liner
syserms discussed are those proposed in
the March 28,1986, preamble to the (51
FR 10707-10711} double liner and
leachate colleciton system rule. The
draft technical guidance document
discusses each liner system with respect
to design, construction, installation, and
operations.
The draft single liner guidance, EPA/
530-SW-85-013, is intended to provide
guidance on design in accordance with
section 3015(a) of RCRA for interim
status waste pilet and for certain
surface impoundments and landfills (40
CFR Part 264.221 and 264.301,
respectively). The new requirements for
interim status waste piles apply to new
units, and replacements and lateral
expansions of existing units. Other
applicable hazardous waste
management units include new landfills
and surface impoundments and lateral
expansions or replacements of existing
landfills and surface impoundments that
have been permitted before November 8,
1964. In addition, the existing single liner
standards of 40 CFR 264.221(a) for
surface impoundments, and 40 CFR
264.301(a) for landfills, are still
applicable to portions of existing units
that are not covered by waste at the
time of permit issuance. Therefore, the
draft single liner guidance is intended to
provide guidance for land disposal
facility owners or operators and EPA
and State regulatory personnel on
designs that the Agency believes meet
the single liner performance standards
of 40 CFR 264.221(a), 264.251(a), and
264.301(a). This document identifies
design, construction, and operation
specifications that can be used by
owners or operators in order to comply
wth the requirements of those lections
of the EPA rules.
Dated: April 13.1987.
J.W. McGraw.
Acting Assistant Administrator for Solid.
[FR Doc. 87-8678 Filed 4-16-87; 8:45 am]
MJJW COM M40-50-M
DEPARTMENT OF COMMERCE
50 CFR Part 652
National Oceanic and Atmospheric
Administration
Atlantic Surf Clam and Ocean Ouahog
Fisheries
AGENCY: National Marine Fisheries
Service (NMFS), NOAA, Commerce.
ACTION: Notice of availability of a
fishery management plan amendment
and request for comments.
SUMMARY: NOAA issues this notice that
the Mid-AUantic Fishery Management
Council has submitted Amendment 7 to
the Fishery Management Plan for the
Atlantic Surf Clam and Ocean Quahog
Fisheries (FMP) for review by the
Secretary of Commerce. Comments are
invited from the public on the
amendment and associated documents,
DATE Comments will be accepted until
June 11,1987.
ADOBES* Send comments to Richard
Schaefer, Acting Regional Director,
Northeast Regional Office, National
Marine Fisheries Service, 14 Elm Street,
Gloucester. MA 01930. Mark "Comments
on Atlantic surf clam and ocean quahog
plan" on the envelope.
Copies of the amendment and its
associated documents are available
from John C. Brysoa Executive Director,
Mid-Atlantic Fishery Management
Council, Room 2115, Federal Building,
300 South New Street, Dover, DE19901-
6790.
FOR FURTHER INFORMATION CONTACT:
Bruce Nichols (plan coordinator), 817-
2B1-3600, ext. 232.
SUPPLEMENTARY INFORMATION: The FMP
and this amendment were prepared
under the Magnuson Fishery
Conservation and ManagemenLAct.
This amendment proposes measures
to (1) change the quarterly quota
allocation for the Georges Bank area
from 10%—40%—40%—10% to 25% for
each quarter, (2) remove for all areas the
5,000 bushel threshold for transfer of
unharvested quota from one quarter to
the next, (3) add the provision that any
unharvested quota in the Nantucket
Shoals and Georges Bank areas be
distributed proportionally among the
remaining quarters of the year, (4)
remove the 10% limit on carryover of
unharvested quota from one year to the
next, (5) require annual renewal of
vessel permits, and (6) change the
regulations to enhance prosecution and
enforcement.
Proposed regulations for this
amendment will be published within 15
days.
(16 U.S.C. 1891 etseq.)
Dated: April 14.1987.
Richard B. Roe,
Director, Office of Fisheries Management,
National Marine Fisheries Service.
[FR Doc. 87-8721 Filed 4-14-87, 5:05 pm]
WLUNO cooc
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APPENDIX C
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Friday
May 29, 1987
Part II
Environmental
Protection Agency
40 CFR Parts 260, 264, 265, 270, and 271
Liners and Leak Detection for Hazardous
Waste Land Disposal Units; Notice of
Proposed Rulemaking
This document is 95 pages
in length. Please order from
your public library.
c-i
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APPENDIX D
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ANALYSIS AND FINGERPRINTING OF UNEXPOSED AND EXPOSED
POLYMERIC MEMBRANE LINERS
Henry E. Haxo, Jr.
Matrecon, Inc.
Oakland, California 94623
ABSTRACT
A- plan is presented for analyzing polymeric mer,,brane liners for waste storage and
disposal Impoundments before and after laboratory or pilot-scale exposure and field ser-
vice. These analyses can be used to fingerprint a material and to follow the changes
that take place in a polymeric membrane Uner during exposure to waste. They can also be
used to determine components of a waste liquid that are absorbed and are aggressive to
polymeric liners.
This analysis plan includes determination of volatiles, extractables, specific
gravity, ash and crystal Unity of polymeric liners. The plan also includes gas chroma-
tography and Infrared analysis of the extractables (and possibly of the organic volatiles)
and thermogravimetrlc analysis of the liner. Also suggested is the use of pyrolysls gas
chromatography, wtiich can be performed directly on unexposed and exposed liner materials.
Typical analytical results for unexposed and exposed liners are presented.
INTRODUCTION
Because of the wide range of composi-
tions and constructions of flexible poly-
meric membrane liners that are currently
available and being developed for lining
waste impoundments, analysis and finger-
printing of the membranes 1s needed for a
number of purposes. For example, a I1°°r
manufacturer needs to test his sheeting as
new polymers are used and as new compounds
and constructions are developed. He also
needs tests to control the composition of
the Uner being manufactured.
The analysis of a polymeric membrane
liner at tne time of placement can be used
for three purposes: first, as a means of
characterizing and Identifying the specific
sheeting; second, as a baseline for moni-
toring the effects of exposure on the Uner;
and third, to assess the aggreslve Ingredi-
ents in the waste liquid to determine
chemical compatibility.
During exposure to waste liquids,
polymeric liners may change in composi-
tion in various ways that may affect their
performance and result 1n actual failures.
Polymeric materials may absorb water,
organic solvents and chemicals, organo-
metallic materials, and possibly some inor-
ganics 1f the liners become highly swollen.
On the other hand, the extractable materials
1n the original Uner compound may be
leacneu out and result in stiffening and
even brlttleness on the part of the Uner
membrane. The solid constituents of a
polymeric compound (which Include carbon
black, Inorganic fillers, and some of the
curing agents) will be retained 1n the Uner
compound, as will tne polymer of which the
Uner 1s made (particularly 1f the polymer
1s crossllnked). If organic materials are
similar to tne liner in solubility and
hydrogen bonding characteristics, the Uner
may swell excessively. Some thermoplastic
D-l
-------
lining materials may even dissolve, when 1n
contact with some solvents.
The objective of this paper Is to
present an analytical methodology that can
be used to fingerprint and Identify Uner
materials and to give a baseline for
assessing the changes 1n composition of
these materials when they are under test or
1n service. Also presented are the analy-.
tlcal procedures for testing exposed liner
materials to determine these changes. Data
on representative liner materials, before
and after waste exposure, are presented.
POLYMERS USED IN MEMBRANE LINER MANUFACTURE
Polymers used in the manufacture of
lining materials include rubbers and
plastics differing in polarity, chemical
resistance, basic composition, etc.,
and can be classified Into four types:
- Rubbers (elastomers) that are gen-
erally crosslinked (vulcanized),
Plastics that are generally urwul-
canized (such as PVC),
Plastics that have a relatively
hlgn crystalline content (such as
the polyoleflns), and
Thermoplastic elastomers
need to be vulcanized.
that do not
Table 1 lists the various types of
polymers that are used and indicates whether
they are used 1n vulcanized or nonvulcanlzed
form and whether they are reinforced with
fabric. The polymeric materials most fre-
quently used in liners are polyvinyl chlo-
ride (PVC), chlorosulfonated polyethylene
(CSPE), chlorinated polyethylene (CPE),
butyl rubber (IIR), ethylene propylene
rubber (EPDM), neoprene (CR), and high-den-
sity polyethylene (HOPE). The thickness of
polymeric membranes for liners ranges from
20 to 120 mils, with most in tne 20 to 60-
mi 1 range.
TABLE 1.POLYMERIC MATERIALS USED IN LINERS
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elastlcized polyolefln
Use
Thermo-
plastic
No
Yes
Yes
Yes
in liners
Fabric
reinforcement
Vulcanized
Yes
Yes
Yes
No
With
Yes
Yes
Yes
No
W/0
Yes
Yes
Yes
Yes
(partially crystalline)
Elastlcized polyvinyl chloride Yes
Epichlorohydrin rubber Yes
Ethylene propylene rubber Yes
Neoprene (chloroprene rubber) No
Nltrile rubber Yes
Polyethylene (partially crystal-
line) Yes
.Polyvinyl chloride Yes
No
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
D-2
-------
Most polymeric lining materials are
based on single polymers, but blends of two
or more polymers (e.g., plastic-rubber
alloys) are being developed and used in
liners. Consequently, it is difficult to
make generic classifications based on
individual polymers in the liners, even
though one polymer may predominate. Blend-
ing of polymers introduces the long-range
possibility of the need for performance
specifications, but long-term liner per-
formance in the field cannot presently be
completely defined by current laboratory
tests.
The basic compositions of the different
types of compounds are shown in Table 2.
The crosslinked rubber compositions are
usually the most complex because they con-
tain a crosslinking system that requires
more ingredients (e.g., the sulfur system).
Thermoplastics, except for CSPE compounds,
contain no curatives. Although supplied as
thermoplastic membranes, CSPE liners con-
tain inorganic crosslinking chemicals that
allow the compound to crosslink slowly over
time during service. Crystalline materials
have the simplest composition and generally
consist of polymer, a small amount of carbon
black for ultra-violet protection, and
antidegradants.
Of the various liner components (except
for the polymer), the following are poten-
tial extractables:
- Small amounts in the original polymer
(I.e., stabilizers and antidegrad-
ants)
- 011s and plastldzers
- Antidegradants added to the compound.
- Organic constituents of the sulfur
crosslinking system (e.g., vulcaniza-
tion accelerators and activators).
These ingredients are extracted in the de-
termination of extractables.
Host of the polymeric membrane liners
currently manufactured are based on unvul-
canized or uncrosslinked compounds and thus
are thermoplastic. Even if the polymer in
the vulcanized form 1s more chemically
resistant (such as CPE and CSPE), it is
generally supplied unvulcanized because it
is easier to obtain reliable seams and to
make repairs in the field. Thermoplastic
polymers can be heat-sealed or seamed with
a solvent or bodied solvent (a solvent con-
taining dissolved polymer to increase the
viscosity and reduce the rate of evapora-
tion). Crystalline sheetings, which are
also thermoplastic, are seamed by thermal
welding or fusion methods. Information on
individual polymers and liners is presented
in the EPA Technical Resource Document on
liners (Matrecon, 1982).
TABLE 2.BASIC COMPOSITIONS OF POLYMERIC MEMBRANE LINER COMPOUNDS
Type of polymeric compound
Component
Crosslinked Thermoplastic Crystalline
Polymer or blends (alloys)
Oil or plasticizer
Fillers:
Carbon black
Inorganics
Antidegradants
Crossllnking system:
Inorganic system
Sulfur system
100
5-40
5-40
5-40
1-2
5-9
5-9
100
5-40
5-40
5-40
1-2
(*}
100
0-10
2-5
1
*An inorganic curing system that crosslinks over time is incorporated
in CSPE Uner compounds.
D-3
-------
ANALYSIS AND FINGERPRINTING OF UNEXPOSED
POLYMERIC LINING MATERIALS
Analyses of liners run before and after
exposure to different environments include:
- Volatiles
- Ash
- Extractables
- Gas chromatography
- Thermogravimetric analysis
- Differential scanning caloMmetry
if liner material is crystalline
- Specific gravity
The following subsections describe the
tests performed on unexposed polymeric
linings.
Volatiles
The volatile fraction is represented by
the weight lost by an unexposed specimen of
the Uner on heating in a circulating air
oven at 105°C for 2 hr. Polymeric compo-
sitions generally contain a small amount of
volatiles (<1.0t), usually moisture. The
recommended specimen 1s a disk cut from the
membrane.
The volatiles test can also be used to
determine the direction of the grain that
has been introduced in the membrane during
manufacture. By identifying the orientation
of the 2-in. disk specimen with respect to
the sheeting at the time the specimen was
died out, the grain direction can be Iden-
tified. The grain direction must be known
so that tensile and tear properties can be
determined in machine (grain) and transverse
directions. Upon h«ating 1n the oven at
105°C, sheeting with a grain will shrink
more in the grain direction than 1n the
transverse direction (Figure 1).
Volatiles need to be removed before
determining ash, extractables, and spec-
ific gravity. Ash and extractables are
reported on a dry basis (db). Volatiles
contents of representative membrane liners
are presented 1n Table 3. Monomeric plas-
tldzers that are generally used 1n PVC
compositions have a limited volatility and
can slowly volatilize at 105°C. Thus the
air oven test must be limited to 2 hr.
As received
After air oven heating
2 hr. at 105°C
Figure 1.Machine direction determinations.
A standard test for the volatility of
plasticizers in PVC compounds is performed
1n accordance with ASTM D1203. In this
test, activated charcoal is used to absorb
volatilized plasticizer.
Ash
The ash content of a liner material is
the inorganic fraction that remains after a
devolatilized sample is thoroughly burned at
550°±2bJC. The ash consists of (1) the
Inorganic materials that have been used as
fillers and curatives 1n the polymeric
coating compound, and (2) ash residues In
the polymer. Different Uner manufacturers
formulate their compounds differently, and
determining the asn content can be a way to
"fingerprint" a polymeric liner compound.
The residue obtained by ashing can be
retained for other analyses (such as metals
content) needed for further Identification
and for providing a reference point to
determine trace metals that may have been
absorbed by the liner. The test method
D-4
-------
described 1n ASTM 0297, Section 34, 1s
generally followed 1n performing this
analysis. Ash contents of representative
membrane liners are presented 1n Table 3.
Extractables
The extractable content of a polymeric
sheeting 1s the fraction of the compound
that can be extracted from a devolatiHzed
sample of the Uner with a solvent that
neither decomposes nor dissolves the poly-
mer. Extractables consist of plastldzers,
oils, or other solvent-soluble constituents
that Impart or help maintain specific
properties such as flexibility and proces-
sabillty. A measurement of extractable
content and an analytical study of the
extract can be used as part of the finger-
printing of a sheeting.
During exposure to a waste, the ex-
tractable constituents 1n a Uner may be
removed and result 1n property changes. At
the same time during exposure, the Uner
might absorb nonvolatlHzable constituents
from a waste. Measuring the extractable
content of unexposed lining materials 1s
therefore useful for monitoring the effects
of exposure. The extract and the extracted
Uner obtained by this procedure can be used
for further analytical testing (e.g., gas
chromatography, Infrared spectroscopy, ash,
thermogravlmetry, etc.) and fingerprinting
of the Uner.
The procedure for extraction generally
follows ASTM D3421, "Extraction and Analysis
of Plastldzer Mixtures from Vinyl Chloride
Plastics". Also see ASTM 0297. "Rubber
Products-Chemical Analysis", paragraphs
16-18.
Because of the wide differences among
the polymers used in liner manufacture, a
variety of extracting media must be used.
TABLE 3. ANALYSIS OF UNEXPOSED POLYMERIC HEM8RANE LINERS*-*
Base polywer,
, Polymer specific grivtty
Butyl rubber
Chlorinated polyetnylene
Cnlorosulfonated poly-
etnylene
Elastlclzed polyolefln
Ep1chloronydr1n rubber
Etnylene propylene rubber
Neoprene
Polybutylene
Polyester elastomer
Polyetnylene (low density)
Polyetnylene (nigh density)
Polyetnylene (high density)
«Uoy
Polyvlnyl uilorlde
0.92
1.16-1.26
1.11
0.92
1.27-1.36
0.86
1.25
0.91
1.17-1.25
0.92
0.96
0.9S
1.40
Compound
Specific
gravity
1.206
1.170
1.360
1.362
1.377
1.433
1.343
0.938
1.490
1.173
1.122
1.199
1.503
1.480
1.390
0.915
1.236
0.921
0.961
0.949
1.275
1.264
1.231
1.280
1.308
Volatlles,
X
0.45
0.46
0.10
0.00
0.05
0.84
0.51
0.15
0.63
0.38
0.50
0.31
0.76
0.19
0.37
0.12
0.26
0.18
0.12
0.11
0.11
0.09
0.05
0.31
0.03
Extractables,
I
10.96
11.79
7.47
9.13
1.49
3.77
5.50
7.27
23.41
31.77
18.16
10.15
13.43
21.46
...
2.74
2.07
0.49
2.09
33.90
37.25
38.91
35.86
25.17
, Asn,
1
5.25
4.28
14.40
12.56
17.37
33.95
3.28
0.90
4.49
6.78
5.42
0.32
12.98
13.43
4.67
0.08
0.38
0.13
0.46
0.32
6.20
5.81
3.65
6.94
5.67
•Source of some of the data
figure* represent
Haxo «t al. (1982).
•atirlals fro* different manufacturers.
D-5
-------
Table 4 lists the recommended solvents for
extraction of membrane liners of each
polymer type.
Typical values for the extractables 1n
polymeric membranes are given 1n Table 3.
Gas Chromatography
Gas Chromatography can be used to find
the level of the plastlclzer (e.g., dlethyl-
hexyl phthalate (DEHP), a dloctyl phthalate)
compounded Into a PVC Uner material. Fig-
ure 2 shows the quantification of DEHP 1n
the solvent extract of a PVC Uner material.
The weight percent of the DEHP 1n the Uner
can then be calculated, assuming the extrac-
tion to be 100X efficient. A typical
procedure 1s summarized below.
A weighed sample of liner is extracted
with an appropriate solvent. The extract is
evaporated to dryness over a steam bath.
The dry residue is redissolved in solvent
and brought to an accurately known volume.
Following the development of appropriate
chromatographic conditions, injection of
this solution into the instrument will
separate it into chemically pure components
characterized by different retention times.
An injection of a DEHP standard solution
will identify the retention time of the DEHP
component. Comparison of the peak height
>
r
0.2
O Snodirdl
+ Sonple
0 I 3 3 « 5 « 7 a 9 10 II
PEAK HEIGHT IN CM
Figure 2.Gas chromatograph determination
of the diethylhexyl phthalate
content in an extract of a PVC
membrane. Column: 6'xl/8" 3% 0V
101 on Chromosorb WHP. Tempera-
ture: 200°-300°C at 8°C/min. He
carrier gas: at 30cc/min.
(area) data obtained from the injection of
equal volumes of the extract solution and
from quantitatively prepared standard
solutions allows the Interpolation of the
DEHP concentration 1n the extract solution
(Figure 2).
TABLE 4. SOLVENTS FOR EXTRACTION OF HULYhtRIC MEMBRANES*
Polymer type
Extraction solvent
Butyl rubber (IIR)
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyolefin
Eplchlorhydrin rubber (CO and ECO)
Ethylene propylene rubber (EPDM)
Neoprene
NHrile rubber (vulcanized)
Nitrlle-modified polyvlnyl chloride
Polyester elastomer
High-density polyethylene (HOPE)
Polyvlnyl chloride (PVC)
Thermoplastic oleflnlc elastomer
Methyl ethyl ketone
n-Heptane
Acetone
Methyl ethyl ketone
Methyl ethyl ketone or acetone
Methyl ethyl ketone
Acetone
Acetone
2:1 blend of carbon tetrachlo-
ride and methyl alcohol
Methyl ethyl ketone
Methyl ethyl ketone
2:1 blend of carbon tetrachlo-
Mde and methyl alcohol
Methyl ethyl ketone
^Because lining materials can be sheetings based on polymeric aloys mar-
keted under a trade name or under the name of only one of polymers, this
11st can only be taken as a guideline for choosing a suitable solvent for
determining the extractables. Once a suitable solvent has been found, 1t
1s Important that the same solvent be used for determining the extract-
ables across the range of exposure periods.
D-6
-------
Pyrolysis gas chromatography
Pyrolysis gas chromatography 1s an
alternative method for measuring a plas-
tlclzer 1n Uner materials. In this tech-
nique, a small, weighed sample of Uner 1s
heated very rapidly to a temperature suf-
ficient to volatilize all of Its organic
components. The plastldzer and other
lower-molecular weight organlcs will be
driven off as chemically unchanged vapors.
The polymer will undergo pyrolysis, or high
temperature decomposition, and will vola-
tilize as lower-molecular-weight organic
compounds. The resulting volatlles may be
separated and quantified by gas chroma-
tography as previously described, and the
plasticizer content of the liner may be
calculated.
This method has the strong advantage of
not requiring extraction of the liner
sample, but it may not be as reliable a
means of quantification because of the very
small sample size and the large number of
components that must be separated by the gas
chromatograph.
Thermogravimetric analysis (TGA)
TGA is a thermal technique for asses-
sing the composition of a material by Its
loss in weight on heating at a controlled
rate 1n an Inert or oxidizing atmosphere.
For example, when a material is heated in an
inert atmosphere from room teirperature to
600°C at a controlled rate, it will vola-
tilize at different temperatures until only
carbon, char and ash remain. The intro-
duction of oxygen Into the system will burn
off the char and carbon black. Thus from
the weight-time curve which can be related
to weight and temperature, the amounts of
volatlles, plasticizer, polymer, carbon
black, and ash can be calculated. In some
cases, thermogravimetric analysis can
replace measurements of the volatlles, ash,
and extractables contents discussed above.
The TGA curve and the derivative of the TGA
curve can thus be used as part of a finger-
print of a polymeric composition. This
technique is described by Reich and Levi
(1971).
A Perkln-Elmer TGS-2 thermogravi-
metric system, consisting of an analyzer
unit, balance control unit, heater control
unit, and first derivative computer, 1s used
1n our laboratory. Temperature control 1s
supplied by the temperature controller on
the Perkln-Elmer DSC-2 (Differential Scan-
ning Calorimeter). A double side-arm fur-
nace tube was used to allow rapid changing
of the atmosphere from Inert (N2) to ox1-
datlve (N2/02 mixture). For the oxida-
tive atmosphere, N2 purge is maintained
through the analyzer unit head, and 02
1s Introduced at the upper side arm where
1t mixes with the N2 to burn the carbon
black and any carbonaceous residue that
forms during the pyrolysis of the polymer.
Use of the double side-arm furnace tube
shortens the turnaround time because 1t
eliminates the need to flush the analyzer
head completely to remove 0? between runs,
as would be necessary if 02 were Intro-
duced through the head. A dual pen recorder
Perkln-Elmer Model 56 allows a simultaneous
display of thermocouple temperature 1n the
furnacfe and the change 1n weight of the
specimen or the first derivative of the
change in weight.
An example of the TGA procedure for the
analysis of a polymeric liner is described
below.
A 5-mg specimen of the liner was placed
in the balance pan and weighed 1n a nitrogen
flow of 40 cc/min. The Instrument was
adjusted to give a 100% full-scale deflec-
tion for the weight of the sample, so the
percent of weight change can be read
directly from the chart.
The specimen was heated to 110°C and
held there for 5 min to determine whether
measurable volatlles were present; it was
then heated from 110° to 650°C at a rate of
20°C/min in a nitrogen atmosphere. The
specimen was held at 650°C until no more
weight loss occurred, usually 2 to 3 min,
after which 1t was cooled to 500°C and 02
was Introduced at a rate of 10 cc/min with
an N2 flow rate of 30 cc/min.
Typical thermograms for HOPE and EPDM
appear in Figures 3 and 4, respectively.
Analyses of a variety of polymeric membrane
liners are presented 1n Table 5.
Differential Scanning Calorimetry (DSC)
DSC 1s a thermal technique for measur-
ing the melting point and the amount
of crystalllnlty 1n partially crystalline
polymers such as the polyolefins polyethy-
lene, polypropylene, and polybutylene.
This technique measures the heat of fu-
sion of a crystalline structure; 1t can
also give an Indication of the modification
of crystalline sheeting with other polymers
D-7
-------
V--H
4 i 12 \i 5 S a n » « *•
TIME. MINUTES
Figure 3.TGA of an unexposed black HOPE liner. The plots of sample weight and temperature
as a function of time are shown. Under an fy atmosphere, the black HOPE sample
lost approximately 95.5X of its mass as hydrocarbons were evolved. The carbon
black added as an ultraviolet light absorber remained as a carbonaceous residue
and was not volatilized until 1t was oxidized when oxygen was allowed Into the
system.
U M
TIME. MINUTES
Figure 4.Thermograv1metr1c analysis of an unexposed EPDM liner membrane. Tne dotted line
shows the temperature program and the solid line shows the percent of the original
specimen weight. At 46 minutes the atmosphere was changed from nitrogen to air
to burn the carbon black.
D-8
-------
TABLE 5.THERMOGRAVIMETR1C ANALYSIS OF POLYMERIC MEMBRANE LINERS
Polymer type
Butyl rubber
Chlorinated
polyethylene
Chlorosulfonated
polyethylene
Volatile*,
I
0
0
0
0.4
1.0
0.9
0.1
Polymer,
%
45.0
72.2
71.3
53.9
49.3
47.7
58.1
U1I or plas-
tldzer, %
12.2
7.6
9.1
13.9
1.5
3.2
5.5
Carbon
black, X
37.1
5.3
6.5
21.0
45.6
45.2
9.8
Ash,
%
5.7
14.9
13.1
10.8
2.6
3.0
26.5
Elasticized
polyolefin
Ep1chlorhydr1n
rubber
Ethylene propylene
93.1
49.3
1.7
8.2
4.0
37.7
1.2
4.8
rubber
Neoprene
Polyethylene (high
density)
Polyvinyl chloride
0.1
0.2
1.0
0
0
0
0
0
0
0
30.8
33.5
42.3
44.0
97.9
95.6
97.0
48.7
46.0
51.0
32.9
23.2
10.7
10.7
U
0
0
38.2
42.1
35.0
30.9
35.5
34.9
33.8
2.1
4.2
1.8
6.2
7.8
7.0
5.3
7.6
11.1
11.5
• • •
0.2
1.2
6.9
4.1
7.0
by alloying. Thus this type of analysis can
be used as a means of fingerprinting crys-
talline polymeric liner materials (partic-
ularly high-density polyethylene) and
assessing the effects of aging and exposure
to wastes. This technique 1s described by
Boyer (1977) and Ke (1966).
The differential scanning calorimeter
used 1n this work was the Perkin-Elmer
Model OSC-2C, equipped with an Intracooler I
subamblent temperature accessory to provide
an operating temperature range of -40 to
The equipment Is used to characterize
the thermal transitions of materials
such as melting, boiling, and changes 1n
crystal structure. A sample and reference
cell are provided. A weighed sample 1s
placed 1n the sample holder; the reference
cell 1s generally run empty to provide an
absence of thermal transitions. The two
cells are simultaneously heated or cooled so
that the average cell temperature follows a
preset program. When the sample undergoes
a thermal transition, an endothermic or
exothermic reaction will occur. The
change 1n power required to maintain the
sample cell at the same temperature as the
reference cell 1s recorded as a deflection
of the recorder pen. The recorder plots the
temperature (°C) versus the differential
energy flow (meal/sec) required to maintain
the sample cell temperature. An endothermic
transition such as melting is shown as a
positive peak; an exothermic reaction such
as crystallization 1s shown as a negative
peak. The magnitudes of these peaks and the
temperatures at which they occur are charac-
teristic of the material analyzed.
An example of the use of the DSC to
determine the polyethylene crystal Unity 1n
an HOPE Uner Is shown 1n Figure 5.
D-9
-------
<
UJ
Endotherm
396 K • Melting Point
" Exotherm
370 330 390 400 410
TEMPERATURE. KELVIN
Figure 5. DSC determination of the poly-
ethylene crystal 1inity in an
HOPE liner. The x-axis 1s the
temperature which was raised at
5°C/min. The y-axis 1s cali-
brated in meal/sec, or rate of
energy flow. A positive deflec-
tion of the plot Indicates that
the sample is absorbing energy
(e.g., during melting). The
amount of energy absorbed during
the melting process may be
determined by calculating the
peak area and relating 1t to the
peak area resulting from the
melting of an Indium standard of
known weight. The energy absorb-
ed is termed the "heat of fusion"
( Hf). Assuming that Hf for
the fully crystalline polymer is
known, the degree of crystal Un-
ity of the sample can be deter-
mined as a simple ratio.
Specific gravity
Specific gravity 1s an Important
characteristic of a material and 1s gen-
erally easy to determine. Because of dif-
ferences 1n the specific gravities of the
base polymers, specific gravity of the Uner
compound can give an Indication of the com-
position and Identification of the polymer.
Specific gravities of base polymers and of
different Uner compounds based on them
are presented 1n Table 3. They show the
the differences among polymers and the
variations 1n compounds from one manu-
facturer to another.
ASTM Method 0792. Method A-l, and D297.
Section 15.1.2, Hydrostatic Method, are
generally used 1n performing this test.
ANALYSIS AND FINGERPRINTING OF EXPOSED
POLYMERIC MEMBRANE LINERS
During service, several processes can
take place to change the composition of a
liner and thus affect physical properties
and possioly performance. First, the Uner
can absorb waste liquids Including water,
various organics, and possibly some Inor-
ganic substances. The composition of the
absorbed chemicals will probably reflect
that of the waste liquid, but It will vary
depending on the relative solution charac-
teristics and the waste liquid constituents.
The absorbed organics can be both volatile
and nonvolatile. The total amount generally
softens the liner, resulting 1n possible
loss of tensile strength and other mechan-
ical properties, loss of elongation, and
increased permeability. While the organic
constituents are being absorbed, some of the
extractables such as plastlcizer and oils
may migrate out of the compound, either by
evaporation, dissolution in waste liquid, or
biodegradatlon. Severe loss of plastldzer
could result in stiffening and loss in
mechanical properties. Losses 1n properties
can occur also through UV degradation and
oxidation of the polymer if the liner is
exposed to the weather. Figure 6 schemati-
cally represents the compositions of a
polymeric liner before and after exposure
and after extractions.
In assessing the long-term effects of
exposure to wastes and the other conditions
in a disposal facility, 1t 1s necessary to
know which waste constituents have affected
the lining material and what degradation may
have taken place. An analysis of exposed
liners 1s most useful to determine these
factors. Figure 7 Illustrates a proposed
plan of analysis that we have used 1n our
analyses of exposed materials, recovered
from the laboratory or the field.
The various tests that are performed on
exposed membranes are the same as those
discussed 1n the previous section for
unexposed lining materials, with mod-
ifications and special precautions required
In each test for the exposed materials.
These Individual tests are described 1nthe
following subsections.
D-10
-------
T
I
~^"^. ^"
^. -•
PLASTICIZEH
FILLER .
POLYMER
XLOflTT
ORIGINAL
LINER
EXfOStO
LINER
WEIGHT INCREASE
. WASTE . .
, ' LIQUID
PLASTICIiER
fILLER
POLYMER
t
1
' • WASTE . '
• LKXJIO .
PLASTIC1ZER
FILLER
POLYUER
. VOLATILE:
VOUATILES
REMOVED
%VOl_ATILES
• MonTvrt
• Orgwuci
~~__^- •• JXTRACTAtLtS
PLASTICHER
. FILLER
VOLATILES
AND
EXTRACT A«LES
* EXTRACTA«LES
Figure 6.Schematic presentation of changes 1n composition of a polymeric liner compound on
exposure to a waste liquid, on removal of volatiles, and on extraction with
an appropriate solvent.
TGA • ttMrmooravwn«vic BAalyi*
GC • t» difonuioftghr
IR • inlririd wKtiotcopy
AAS • itonx •bie'piion icwct'oicopv
CHONS • cvbon, hvdro9tn. nrtro9*n, oiyotn, *
ujllur d«tt rmtntnton
Figure 7.Plan for the analysis of exposed polymeric lining materials.
D-ll
-------
VolatHes
The initial analytical test generally
performed 1s a determination of the vola-
tile* content, which gives an Indication of
the amount of waste liquid that has been ab-
sorbed by the Uner. As an approximation,
the weight Increase can be calculated by
dividing the percent of volatlles by the
percent of nonvolatlles. For example, 1f
the volatlles are 15X. and the nonvolatlles
are 85X, the percent Increase 1n weight
based on the original Hner would be 17.6%.
Inasmuch as the volatlles contain
both water and organic components, 1t
1s desirable to separate these two. A
study was made to dehydrate the speci-
mens of the exposed Hner to remove the
water. A series of deslccants was stud-
led at room temperature and 50°C. Four
days of exposure of the exposed Hner at
50°C 1n a small Individual desiccator
containing calcium chloride removed the
moisture from the 2-in. disk specimen
without removing organic constituents.
After removal of the water, a 2-hr heating
of the specimen 1n a circulating air oven
removed the remaining organic volatlles.
Collection of the organic volatlles and
determination of composition by gas
chromatography would be desirable but
has not been attempted to date. The
water and the organic volatlles equal
the volatlles obtained 1n bypassing the
desiccator exposure. Such a bypass removes
the moisture by exposure at room temperature
for 1 week 1n moving air followed by heating
in a circulating air oven for 20 hr at 50°C
and 2 hr at 105°C. We have found, however,
that the highly swollen CPE Hner may take
up to 6 days at 50°C to come to constant
weight. The time required to remove
volatlles depends on the thickness and
permeability of the liner and the care taken
to avoid the "skin" tnat forms on the
surface of the specimen when using too high
an initial temperature to devolatil1ze.
After the volatlles are removed, the
exposed materials can be subjected to
the other tests, Including specific gravity,
extractables, ashing, etc.
Total volatlles can also be determined
through the use of TGA which 1s discussed
below.
Extractables
Extractables of
will probably differ
exposed materials
from the original
values because of the loss to the waste
liquid and absorption of nonvolatile
organlcs (e.g., oils). After the vol-
atiles have been re»oved from the liner,
the extractables are determined by the same
method used on the unexposed Hner materi-
als. Examples of extractable contents after
exposure are given 1n Table 6. If the Hner
has been in contact with wastes containing
nonvolatile constituents, the extractables
recovered may be greater than the original
values. Analysis of tne extractables by gas
chromatography and Infrared analysis may
give an indication of the nonvolatile
organlcs that were absorbed. The analysis of
the extractables will give an Indication of
the constituents of the waste that are
aggressive to the Uner, as they are the
constituents that have been absorbed. They
may show up in minor amounts in a waste
analysis, but because of their chemical
characteristics such as solubility parame-
ters and hydrogen bonding, they may be
scavenged by the polymeric liner.
Ash
Thp ash content of an exposed membrane
Hner 1s determined after the volatlles have
been removed from the specimen. As in the
case of the unexposed oembrane, the exposed
Hner is ashed in a muffle furnace at
550°C. The ash value usually differs from
that of the unexposed material, depending on
how many nonvolatile organlcs were lost or
gained during the exposure period. If plas-
tlcizer is lost, the value will increase
because of the nonash content of the plasti-
cizer. Also, 1f any organic metal compounds
are absorbed by the liner, they will show as
an Increased ash content. A comparison of
the elemental analysis of the ash with that
of the original Hner will determine whether
any absorption of netal species occurred
during the exposure. Ho such absorption has
been observed, but aetal organlcs might be
absorbed by a liner. In general, the In-
organics that make up the ash are retained
in the liner and maintain a constant ratio
with respect to the polymer content, as
polymer 1s generally not dissolved by the
waste liquid.
Thermograv1metr1c analysis
The TGA analysis can be used to give a
quick analysis of the composition of an
exposed polymeric neobrane liner. The test
1s run similarly to that of the unexposed
material, except that care must be taken 1h
handling the small specimens of exposed
D-12
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TABLE 6.EXTRACTABLES OF DIFFERENT POLYMERIC MEMBRANE LINERS
BEFORE AND AFTER VARIOUS EXPOSURES
Polymer
Butyl rubber
Un exposed
11.79
Type of exposure
by waste
Aromatic oil
Spent caustic
Oil 104
Extractables
after exposure
27.23
10.87
40.34
Chlorinated
polyethylene 9.13
Chlorosulfonated
polyethylene 4.08
Elastlcized
polyolefln 5.50
Ethylene prop-
ylene rubber 23.64
Neoprene 21.46
Polyvlnyl
chloride 33.90
011 104
Roof exposure
Aromatic oil
011 104
Slop water
011 104
Aromatic oil
Slop water
Aromatic oil
011 104
Spent caustic
Aromatic oil
011 104
Slop water
Aromatic oil
Roof exposure
Pesticide
011 104
17.00
5.99
59.81
15.92
3.70
20.74
23.37
2.96
38.35
43.45
22.89
58.47
23.85
17.63
40.55
26.27
35.38
17.95
liners that contain the volatlles. These
volatlles can be easily lost. Figure 8 1s a
thermogram of an exposed PVC membrane liner
that had absorbed more than 7X of the waste
liquid, which was predominantly water. The
results are shown on the figure, but the
losses show the effect of the char formation
of the PVC when 1t 1s heated in a nitrogen
atmosphere. Chlorinated polymers lose HC1
and leave a char for which correction must
be made in the calculations of the polymer
content. These calculations have been made
on the figure, and the results compare fa-
vorably with those obtained by direct analy-
sis of the volatiles, extractables, and ash.
Specific gravity
The specific gravity of exposed mem-
brane liners is also determined after the
membrane specimen has been thoroughly de-
volatilized. Three steps must be taken to
avoid the formation of bubbles in the liner
mass during a direct devolatilizing process
(which would affect the specific gravity
results). First, the specimens must be
allowed to "dry" at room temperature in an
air stream in a hood until constant weight
is achieved, which could take several days.
Second, they must be placed 1n an oven at
70°C for 16 hr; and third, they must be
heated at 105°C for 2 hr.
The specific gravity of an exposed
membrane can differ from that before ex-
posure, depending on how much of the origi-
nal extractable material was lost and how
much material from the waste was absorbed
during exposure. The procedure followed was
ASTM D297 using the hydrostatic method.
D-13
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1000
so ao
TIME. MINUTES
140
180
Figure 8. TGA of an exposed polymeric PVC liner.
Weight loss A
Height loss B
Weight loss C
Weight loss 0
Residue weight E
7.0% volatiles - moisture + possible organics.
60.21 = plasticizer + HC1 from the polymer (PVC).
16.OS * residual polymer.
10.01 « carbonaceous polymer residue + carbon black
6.8% = ash.
Composition of the exposed liner as received calculated from above data.
Values by direct analysis are shown in parentheses.
Volatiles 7.0% (7.9)a
Polymer (PVC) 44.7%
Plasticizer 34.1% (32.2% as extractables)a
Carbon black 7.4%
Ash 6.8% (6.4)a
aBy direct analysis.
SUMMARY AND CONCLUSIONS
A protocol 1s presented for the analysis
of polymeric membrane lining materials
before and after exposure to waste .liquid.
The results of the analysis can be used
as a fingerprint of the unexposed Hner and
as a baseline for assessing the changes that
occurred during exposure to a waste liquid.
The analysis of an exposed liner
furnishes Information regarding the change
in the composition of the membrane and the
chemical materials that are actually absorb-
ed during exposure. This latter Information
Indicates the constituents of the waste that
are aggressive to the lining material.
Thermal analysis and gas chromatography
are particularly useful 1n the analysis
and fingerprinting of polymeric membranes.
The use of gas chromatography coupled
with mass spectroscopy needs to be investi-
gated to determine the specific chemicals
that are absorbed by a polymeric Uner.
The use of this analysis may lead to
techniques which will better predict the
service life of a flexible membrane Hner.
ACKNOWLEDGEMENTS
work reported 1n this paper was
performed under Contracts 68-03-2134
("Evaluation of Liner Materials Exposed to
Leachate"), 68-03-2173 ("Evaluation of Liner
Materials Exposed to Hazardous and Toxic
Wastes"), and 68-03-2969 ("Long-term Testing
of Liner Materials") with the Municipal En-
vironmental Research Laboratory of the U. S.
Environmental Protection Agency, Cincinnati,
Ohio.
D-14
-------
The author wishes to thank Robert E.
Landreth, Project Officer, for his support
and guidance 1n these projects.
REFERENCES
ASTM Standards, American Society for Testing
and Materials, Philadelphia, PA.
0297-81, Rubber Products - Chemical
Analyses: Section 15, Density (Hydro-
static Method); Section 34, Fillers,
Referee Ash Method
D792-66, Specific Gravity and Density of
Plastics by Displacement; Method A-l
for Testing Solid Plastics 1n Water,
Sections 6-12.
01203-67, Volatile Loss from Plastics
Using Activated Carbon Methods.
03421-75, Extraction and Analysis of
Plastlcizers from Vinyl Chloride
Plastics
Boyer, R. F. 1977. Transitions and Relaxa-
tions. In: Encycl. Polymer. Sc1.
Technol. Supplement, Vol. 2. pp
745-839.
Haxo, H. E. 1983. Liner Materials Exposed
to Hazardous and Toxic Wastes. Final
Report. Contract 68-02-2173. U. S.
Environmental Protection Agency,
Cincinnati, OH. In preparation.
Haxo, H. E., R. M. White, P. D. Haxo, and M.
H. Fong. 1982. Liner Materials
Exposed to Municipal Solid Waste
Leachate. Final Report. Contract
68-03-2134. U. S. Environmental
Protection Agency, Cincinnati, OH. In
press.
Ke, B. 1971. Differential Thermal Analy-
sis. In: Encycl. Polymer. Sc1.
Technol. Vol 5, pp 37-65.
Matrecon, Inc. 1982. Lining of Waste
Impoundment and Disposal Facilities.
SW-870, Second Edition. U.S. Environ-
mental Protection Agency. Washington,
DC. In press.
Reich, L., and D.
gravimetric
Polymer Sci,
1-41.
W. Lev1.
Analysis.
Technol.
1971.
In:
Vol
Thermo-
Encycl.
14. pp
D-15
-------
APPENDIX E
-------
DRAFT
RCRA GUIDANCE DOCUMENT
LANDFILL DESIGN
FINAL COVER
-------
E. Cap ;?inal rover) resign
1. The Regulation
The cap or final cover must be resigned to .T.ir.i.-izs infil-
tration of precipitation into the landfill after closure. I"
must be no r.ore permeable than the liner system. It -ust
operate with minimum maintenance and promote drainage from its
surface while minimislr.g erosion. It must also oe designed so
that settling and sucsidence are accommodated to minimize tne
potential for disruption of continuity and function of tne final
cover.
2. Guidance
4
(a) The cap or f-inai cover should be placed over each
cell as it is completed. In cases where landfills are operated
with multiple lifts (ceils placed vertically on top of each
other), final cover cannot, of course, be placed until the final
lift is completed, although interim cover should be added to
each cell as it is completed to minimize precipitation inflow.
Where possible, when large cells are used, final cover should
be placed as filling progresses. This is often possible with
trench operations, where filling progresses from one end of
the trench to tne other.
(b) The cap (final cover) should consist of tne following
as a minimum:
(1) A vegetated top cover, as described in paragrapn (c)
of this section;
:2) A middle drainage layer, as described in paragraph
(d) of this section; and
E-l
-------
; 3) A lew permeability borrcm layer as described in
paragraph (e) of "his section.
(c) The vegetated top cover should:
'!) 3e at least 60 centimeters (24 ir.cnes) tnic.<;
(2) Support vegetation that will effectively minimize
erosion witnout need for continuing application of fertilizers,
irrigation, or other .-nan-applied materials to ensure viability
and persistence. fertilizers, water, and other materials may
be applied during the closure or post-closure period if necessary
to establish vegetation or to repair damage.);
(3) Be planted wi~n persistent species that will effect-
ively minimize erosion, and that do not have a root system
that will penetrate, beyond the vegetative and drainage layer;
(4) Have a final top slope, after allowance for settling
and subsidence, of between three and five percent, unless the
owner or operator x:nows that an alternate slope will effectively
promote drainage and not suoject the closed facility to erosion.
f
For slopes exceeding five percent, the maximum erosion rate
should not exceed 2.0 tons/acre per year using the USDA Universal
Soil Loss Equation (USLS); and
(5) Have a surface drainage system capable of conducting
run-off across the cap without forming erosion rills and gullies.
(d) The drainage layer should:
(1) 3e at least 30 centimeters (12 inches) thicic with a sat-
urated hydraulic conductivity not less than 1 X 10~3 cm/sec;
(2) Have a final bottom slope of at least two percent,
E-2
-------
after allowance for settling and subsiiep.ee;
(3) To prevent clogging, be overlain by a graded granular
or synthetic fabric filter that meets tne specifications of
section C. 2. b. of this guidance; and
(4) 3e designed so tnat discharge flows freely in ~ne
lateral direction to minimize head on and flow througn rhe low
permeability layer.
"X
(e) The low permeability layers-should have two components:
' 1) The upp~eT~~componon1r^fhould :
(A) Consist of at least a 20 mil synthetic-membrane;
(3) 3e protected from damage below and above the membrane
*
by at least 15 centimeters '6 inches) of bedding material no
coarser than Unified Soil Classification System (USCS) sand (SP)
and which is free of rocx., fractured stone, debris, cobbles,
rubbish, roots, and sudden changes in grade (slope). The drain-
age layer and lower soil (clay) component may serve as bedding
materials when in direct contact with synthetic caps if they
meet the specifications contained herein;
(C) Have a final upper slope 'in contact witn tne bedding
material) of at least two percent after allowance for settling;
and
(D) Be located wholly below the average depth of frost
penetration in the area.
(2) The lower component snould:
(A) Include at least 60 centimeters (24 inches) of soil
recompacted to a saturated hydraulic conductivity of not more
than 1 X 10~7 cm/sec;
E-3
-------
,3) Have tr.e soil emplaced in lifts not exceeding lo
centimeters (6 ir.cnes) before compaction to maximize the
effectiveness of compaction; ,,
'f; In designing tne final cover, owners and operators
should estimate and accommodate the amount of settling and
subsidence expected as a result of:
(1) The incorporation of containerized liquids prior to
the can imposed March 22, 1932 (U7 ?R 12316); and
(2) Degradation and long-term consolidation of waste.
3. Discussion
The guidance calls for placing the final cover at closure
of each cell or, preferably, as filling of the cell progresse
In some cases, such as when operations are conducted in multiple
lifts, final cover cannot be applied .intil the top cell is filled.
Less substantial, interim cover should be applied to other cells
in multiple lift landfills.
The Agency believes that a three layer final cover (cap)
will adequately minimize infiltration of precipitation, which is
the primary purpose of the final cover. The final cover acts to
minimize infiltration by causing precipitation to run off through
use of slopes, drainage layers, and impermeable and slightly
permeable barriers. 3y minimizing infiltration, the generation
of leachate will also be minimized, thereby reducing long-term
discharge of pollutants to the ground water to a bare minimum.
To prevent the "bathtub effect,1' i.e., to prevent the landfill*
from filling with leachate after closure when the leachate
collection system ceases to function, the final cover must be no
E-4
-------
more permeable tnan "he rr.cst i~perr.eacle 3c~.pcr.er.1: of zc.e _lr.er
system (or of the underlying soils;, in this way, r.c r.cre pre-
cipitation is allowed to infiltrate tne ceil than can escape
tr.rcugh the bottom liner- Prevention of ^he ''batntub effect"
is important to eliminate tne possibility of surface overflew or
migration through porous surface strata. The latter phenomenon
is largely tne cause of the problems at _ove Canal in .Hew Yor-c.
Cther functions of tne fina_ cover include crevention of
contamination o£> surface run-off, prevention of wind dispersal
of hazardous wastes, and prevention of direct contact with
hazardous wastes oy people and animals straying onto the site.
#
The top layer should nave at least two feet of soil capable
of sustaining plant species which will effectively minimize
erosion. Two feet was chosen because it will accommodate
the root systems of most nonwoody cover plantings and is typical
practice within the waste management industry today.
Species planted should not require continuing man-made appli-
cations of water or fertilizers to sustain growth since such
applications cannot be guaranteed in tne long term. Application
of water and fertilizer is, of course, acceptable during the
early stages of the post-closure care period as the plant growth
is being established. The plant species chosen should also
not ha've'-root systems which can be expected to penetrate beyond
the vegetated and drainage layers. If they penetrate deeper,
they can damage the integrity of the low permeability layer.
After allowance for settling and subsidence, the final slope
should be at least three percent to prevent pooling due to irreg-.
E-5
-------
iarities of tne surface and vegetation, cue
cent: to prevent: excessive erosion. The Agency recognizes tr.at
for some landfills operated with multiple vertical lifts or
operated as piles, limiting final slope to five percent may
not oe practical. Owners and operators using different final
slopes should determine that an alternate slope will not be
beset with erosion problems and that it will promote efficient
drainage. The U.S. Department of Agriculture universal Soil
Loss Equation (U*5LE) is recommended as a tool for use in eval-
uating erosion potential. The LISLE predicts average annual soil
loss as the product of six quantifiable factors. The equation is
A = RKE3CP
where A = average annual soil loss, in tons/acre
R = rainfall and run-off erosivity
X = soil erodi'oiiity. factor, tons/acre
L = slope-length factor
3 = slope-steepness factor
C = cover/management factor
P = practice factor
The data necessary as input to this equation is described
in Evaluating Cover Systems for Solid and Hazardous Waste
(SW-S67) September 1980, U.S. EPA. The maximum annual rate of
erosion for any part, of the cover should not exceed 2.0 tons/acre
in order to minimize the potential for gully development and
future maintenance. 'The agricultural data base indicates that
rates as low as 1/3 ton/acre are achievable for a silt-loam
soil, sloped 4 percent witn a blue grass vegetative cover.
The Agency believes that 2 tons/acre can be more readily achieved
E-6
-------
and does not significantly increase cover maintenance. The
top layer should also have some means of conducting run-off
(e.g., swales or conduits) to .safely pass run-off velocities
and volume without eroding the cover.
The second layer or drainage layer is analogous in function
to the ieachate collection system over the liner. It should be
at least 12 inches thicK to provide capacity to handle water
from major sustained storm events, and should be constructed of
porous materials* (at least 1 X 10~3 cm/sec hydraulic conduc-
tivity). Drainage tiles or other collection devices are not
necessary. The Agency-believes that the combination of very
«
porous media, a final-minimum two percent slope after settling,
and the impermeable" nature of the layer beneath will effectively
conduct precipitation infiltrating the vegetative layer off of
the landfill. As with the ieachate collection system, the
drainage layer should be overlain with a graduated granular
or synthetic fabric filter to prevent plugging of the porous
media with fine earth particles carried down from the vegetated
layer. To' prevent fluid from backing up into the drainage
layer, the discharge at the side should flow freely.
The function of the low permeability layer is to reject
fluid transmission, thereby causing infiltrating precipitation
to exit through the drainage layer. It should consist of
at least two components. The upper component should be at
least a 20 mil thicic synthetic membrane. While the regulations
do not specify that the final cover prevent infiltration, the
requirement that it be no more permeable than the bottom
E-7
-------
liner, as a practical matter, necessitates the use of a synthetic
membrane. This is so because the regulatory requirement Tor
the liner system does specify that leachate be contained and
this will be translated, in most cases, into a very nearly
impermeable synthetic membrane liner-
The minimum thickness recommended for the synthetic component:
of the cap (20 mil) is less than that specified for the liner
(30 mil) because '!) the cap is not expected to come in contact
with chemical leachates which might hasten failure, and (2)
once placed, the potential for damage is small as compared to
the potential for bottom liner- damage where waste is placed on
the liner througnout the operating life of the cell. While
intact (30 -t- years in the absence of damage), the synthetic
component will essentially prevent transfer of precipitation
through it and ieachate production should be very nearly zero-
As with liners, synthetic caps should be protected from
punture and tears by at least six inches of bedding materials
In most cases, the drainage layer media above the synthetic
cap, together with the soil (clay) liner under it, can effectively
function as the bedding material.
Even with protection from damage, the synthetic cap will
not las.t forever. At some point in the future, the synthetic
membrane will degrade. At that time, the function of minimizing
infiltration will fall to the second component, a 2-foot minimum
clay soil cap with a maximum hydraulic conductivity of 1 X
10~? cm/sec. Although some small amount of precipitation
will seep through this secondary cap, the amount of leachate
E-8
-------
generated will oe quite small and escape to ground water snculd
be minimal. Unless damaged or affected oy differential settlement,
the secondary soil layer should remain intact and effective
into the distant future. One source of damage that can disrupt
the 'continuity of the impermeable layers is frost heaving.
For this reason, the impermeable layer should be wholly oelow
the average depth of frost penetration in the area. In some
parts of the country meeting this requirement will necessitate
a thicker cap than would otherwise be necessary.
One of the more difficult problems associated with de-
signing final cover for landfills is how to allow for settlement
^
especially differential settlement. Settlement occurs as "a
result of natural compaction and consolidation and biological
degradation of organics. It can to be uniformly distributed
and can occur before or shortly after closure. Differential
\S
settlement ^unevenly distributed and can cause disruption in
continuity of the final cover- One cause of differential
settlement is the collapse of drums which have released liquids.
Settlement from this source may not occur for a number of
years following closure. For new landfills and for new cells
not located over existing cells, subsidence due to drum collapse
should not be a problem. As of March 27, 1982, liquids in con-
tainers .have been essentially banned from landfills (47 PR 12316).
EPA intends to develop specific design requirements which
will ensure adequate allowance for settlement. As of this
writing, however, the Agency iacKs sufficient information to
judge the effectiveness of various design options. 'Therefore,
E-9
-------
tnis guidance suggests si.r.ply that owners and operators estimate
the amount of suosidence and allow for it in the final 3over desig:
as best they can. The final result should be a minimum three
percent final slope after settling and subsidence. luring the
post-closure period, the regulations require that disruption
of the continuity and slope of the final cover be repaired.
The owner or operator must allow for subsidence and settling in
the facility design. As the Agency evaluates alternative
methods of designing final cover to effectively allow for
settling and subsidence, it will issue further guidance or
perhaps even regulations covering the subject.
One suggestion which owners and operators may consider as
a means of at least, partially accomodating settling and
subsidence, is to stage final closure and the placement of the
final cover. Field data indicates to EPA to that most settlment
problems occur soon after closure. It may be preferable
delay placement of the final cover for six months or more in
those cases where substantial subsidence or settlement are
expected. By so doing, expensive repairs to the final cover
may be avoided. This would require an extension in the 180
day limit to the closure period imposed in Subpart G. In
deciding whether to grant such an extension in accordance with
the rules 'oT Subpart G, the permitting official will normally
require installation of an expendable interim cover, capable
of minimizing precipitation migration into the landfill, unless *
E-10
-------
j.c is clear "hat; the liner and leachate collection
systems are functioning and are expected to continue to function
during the extended closure period. The Agency solicits infor-
mation on the effectiveness of this and other approaches to
dealing with the settling/subsidence problem.
E-ll
-------
APPENDIX F
-------
INSTALLATION AND OPERATING INSTRUCTIONS FOR THE
SEALED-DOUBLE RING INFILTROMETER
INTRODUCTION
The Sealed-Double Ring Infiltrometer (SDRI) can be used to measure
the vertical, one-dimensional infiltration rate of water through soil. A schematic
of the set-up is shown in Fig. 1. The infiltrometer consists of an outer and an
inner ring. The rings are embedded in the soil, the outer ring to a depth of 14
in. to 18 in., the inner ring to a depth of 4 in. to 6 in., centered within the outer
ring. The outer ring is open. The inner ring is shorter than the outer ring and
has a top. Both rings are filled with water. The outer ring is filled to a depth of
approximately 12 in., submerging the inner ring. The top on the inner ring seals
the water within it from the atmosphere.
Measurement of flow is made by connecting a flexible bag, filled with a
'known weight of water, to a port on the inner ring. As water infiltrates the
ground and leaves the sealed inner ring, it is replaced with an equal amount of
water drawn in from the flexible bag. After a known interval of time, the flexible
bag is removed and weighed. The weight loss, converted to a volume, is equal
to the amount of water that has infiltrated the ground. An infiltration rate,
usually expressed in cm/sec, is then determined using this volume of water, the
area of the inner ring, and the interval of time that the bag was connected to the
inner ring. This process is repeated and a plot of infiltration versus time is
constructed. The test is continued until the infiltration rate becomes steady or
until it becomes equals to or less than a specified value.
The advantage of the SDRI over other infiltrometers is the capability to
measure low infiltration rates. This is accomplished by measuring the actual
quantity of flow rather than a drop of elevation in the water level and by
eliminating evaporation from the ring where measurements are made.
(12/87)
-------
CHECK PARTS
First check to see that the following parts were included with the Sealed
Double Ring Infiltrometer:
a. 4 - aluminum panels approximately 12' x 38"
b. 1-fiberglass inner ring approximately 5'x 5'
c. 36 - of each of the following: 3/8" round head bolts and nuts
d. 2 - flexible bags
e. 2 - brass valves with barbed connectors on each end
f. 1 -1/2" NPT pipe plug
g. 1 - 1/2" NPT fitting with straight-barbed connector
h. 1 -1/2" NPT fitting with elbow -barbed connector
i. 1-15' length of 3/8"od x 1/4Mid clear plastic tubing
j. 1 - 1/4" brass plug fitting for sealing end of plastic tubing
k. 1 - tee fitting
I. 4 - rubber gasket strips
m. length of cable to keep outer ring from bowing
In addition to the list above, the following items will be needed to
assemble and install the SORI:
a. 1 - flat bladed screw driver for assembling the outer ring
b. 1 - 9/16" wrench for assembling the outer ring
c. 1 - brick hammer for excavating trench for the inner ring
d. 1 - adjustable wrench for installing fittings on inner ring
e. 1 - knife or scissors for cutting tubing
f. 1 - trenching machine for excavating outer ring trench
g. 5 - 5 gal. buckets to mix grout and place on inner ring
h. water supply - approximately 1200 gallons is needed to fill rings
i. bentonite grout to place in trenches
j. sheet of opaque plastic or tarp to cover outer ring
k. 1 - thermometer to monitor temperature in outer ring
I. sheets of polystyrene foam to float on water in outer ring if the
temperature of the water
changes significantly
m. 1 - scale to measure the depth of the water in the outer ring.
n. grout mixer, shovels, and wheelbarrows for preparing grout.
o. cinder blocks to stand on when connecting fittings to inner ring
and also to support
flexible bag.
p. trowel
(12/87)
F-2
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ASSEMBLY OF OUTER RING
1. Carefully uncrate the aluminum panels. Save the crate for
future shipping and also for use during the test.
2. Carefully tilt up two adjacent panels so that their edges line
up and the 3/8" bolts can be inserted through the holes.
Support the panels on both ends so that they are not
accidentally bent.
3. Wipe off the edges of the panels around the bolts holes and
also wipe off one of the rubber gasket strips.
4. Insert the rubber gasket between the two edges and align it
with the bolt holes. The edge with the 900 bend should be
on the outside (Fig. 2).
5. Install nuts and bolts along the edge of the panel.
6. Tilt up the remaining two panels, one at a time, and bolt the
edges together as described above. Be sure to support the
panels during the assembly process.
(12/87)
F-3
-------
EXCAVATION OF TRENCHES
The soil to be tested should not be allowed to dry between the time of
construction and the time of the test. An easy method of protecting the area to
be tested is to cover it with sheets of plastic. Plastic sheets, 20* x 100', are
readily available at most building supply stores. Spreading a thin layer of soil
over the plastic will prevent it from blowing away. When excavating the
trenches, rather than removing a whole sheet, cut strips out of the plastic sheets
where necessary. This will keep most of the soil protected. Water should be
sprayed on any soil that is exposed for long periods of time to prevent
dessication.
The area to be tested should be relatively level with a slope no greater
than 4" over 12'. Slopes of this magnitude are difficult to detect by eye, so a
surveyor's level should be used to check elevations. If the area is not level, be
sure to compensate for this when excavating the trenches. The trenches will
have to be dug deeper in the high areas.
The procedure for excavating the trenches is described below.
OUTER RING
1. Set the outer ring on the area to be tested.
2. Use the lower edge of the ring as a guide and scribe a mark
on the ground where the trench is to be excavated.
3. Note the orientation of the ring and place it aside while the
trench is being excavated.
4. Extend the scribe marks approximately 5' beyond each
corner in order to assist in keeping trencing machine
aligned.
5. Use a trenching machine to excavate the trench. Select a
trenching machine that makes as narrow a trench as
possible, no more than 4" - 6" in width. Tha depth of the
trench should be between 14 and 18 inches. As noted
before, compensate for the test area not being level by
excavating deeper in high spots so that the ring will be
level. Also, since the trenching machine digs at an angle, it
can not cut a verticle corner at the end of each trench.
Rather than going beyond the corner and over excavating,
dig the corner out by hand. Be sure to keep the trench
moist to prevent dessication.
6. Once the trench has been excavated, carefully place the
outer ring in the trench to check that it fits. Check that the
(12/87)
F-4
-------
ring is level (±1"). Set the ring aside and cover the trench to
keep the soil from drying until the grout is prepared.
INNER RING
1. Center the fiberglass inner ring in the area encompassed
by the outer ring. Use the edge of the ring as a guide and
scribe a line in the soil to mark where the trench is to be
excavated.
2. Note the orientation of the ring and set it aside.
3. Use the brick hammer to excavate a narrow trench. The
trench should be approximately 2" wide and 6" deep. When
using the brick hammer, it is best to start by digging down
several inches in one spot and then advancing the trench
foward by chopping down on the soil. Try not to pry the soil
up as this tends to lift up large wedges of soil, open cracks,
and causes the trench to be oversized .
4. Place the inner ring in the trench to check the fit. Excavate
any areas where the ring does not fit. Use a surveyor's
level to check the elevation of the corners of the ring. The
inner ring needs to be level or tilted so that the low end is
slightly below horizontal. If the low end of the ring is above
horizontal, air may be trapped when the ring is filled with
water.
5. Set the ring aside and cover the trenches.
(12/87)
F-5
-------
INSTALLATION OF THE RINGS
PREPARATION OF GROUT
A product sold by American Colloid called "Volclay Grout" works well for
sealing the rings. Between 15 to 20 bags of Volclay Grout are needed for 4"
wide by 18" deep trench. If this product is used, add between 15-20 gallons of
water per 50 pound bag. The most convenient way of mixing the grout is to use
a 4 bag grout mixer. Two bags of grout can be prepared at a time. First add 15
gallons of water to the mixer and then slowly add the grout. Adding the grout to
quickly will result in a mixture with large clumps. Add 15 more gallons of water
and then add the second bag. Add additional water as needed until the grout
flows easily.
OUTER RING
1. Prepare enough grout to fill the outer ring.
2. Remove the cover from the outer ring trenches and clean all
loose dirt out of the trench.
3. Use a wheelbarrow to place grout in the outer ring trench.
Use a sheet of plywood from the outer ring crate as a splash
board to guide grout into trench and from getting on ground
inside the trenches
4. With one person at each corner of the outer ring, lift it and
center it over the trench. Slowly push the ring in place
while keeping it level. Once in place, use a trowel to push
the grout against both the inside and the outside of the ring ,
particularly at the corners, to obtain a good seal.
5. Connect the cable to the top of the outer ring in order to
keep it from bowing when it is filled with water. Thread the
cable, in one long piece and in a diamond shaped
pattern(Fig. 3), from the center hole in the top of one panel
to the center hole in an adjacent panel and so on until the
cable is back to the starting point. Remove the slack from
the cable, twist it to fasten it in place. Do not overtighten the
cable such that the panels are bowed in.
6. Pile loose soil (12") all around the outside edge of the
outer ring (Fig. 4). This will prevent the ring from bowing
and also keep the grout from being pushed out of the trench
when the ring is filled with water.
INNER RING
(12/87)
F-6
-------
1. Prepare a thicker mix of grout for the inner ring trench.
2. Remove the cover from the inner ring trench and clean all
the loose dirt out of the trench. Also clean off the surface of
the area surrounded by the inner ring trench.
3. Fill the trench to within 3/4" of the top. Rod the grout to
remove any air pockets.
4. Lift the inner ring and center it over the trench. Lower it into
the trench and push it down into place. Use a surveyor's
level to check the elevation of the corners of the ring. Make
sure that the lower end of the ring is not tilted or raised
above horizontal as discussed before.
5. Use a trowel to press the grout against the outside wall of
the ring in order to obtain a good seal.
6. Cover the grout to prevent dessication
(12/87)
F-7
-------
FILLING THE RINGS
It is best to fill the rings slowly so that the seal can be checked for leaks.
It is much easier to repair a leak when the water level is low than when it is high.
When filling the inner ring, it is important to realize that water causes an
uplift force to act on the ring. If the ring is filled to too high a level, the uplift
forces can lift the ring out of the ground. For this reason buckets of water are
placed on the inner ring before water is is added to it.
The general procedure for filling the rings is as follows. First, the inner
ring is partially filled and let to sit to check its seal. Next, the outer ring filled.
The ports on the inner ring are left open so it will fill as the water level in the
outer ring rises.
The fittings are attached to the inner ring after the outer ring is filled. The
cinder blocks are used to provide a place to stand when attaching the fittings.
Place several cinder blocks on the ground in the vicinity of ports on the inner
ring. Also place several cinder blocks on the ground just inside the outer ring to
provide a place to lay the flexible bag during the test.
Detailed instructions for filling the rings are given below.
INNER RING
1. Fill two buckets with water and place one on each corners
of the low edge of the inner ring. Make sure that the
buckets are placed on the edge of the ring and not in the
center of the ring as this may cause the fiberglass to crack.
Try not to spill any water around the inner ring as it will
make it difficult to check for leaks around the seal later on.
2. Invert one bucket on the ground near the ports on the inner
ring. Fill a second bucket with water and place it on the
inverted bucket.
3. Cut a length of the flexible tubing long enough to reach
from the bucket to the top port. Use this tube to siphon the
water from the bucket to the inner ring. Siphon a total of
three buckets (15 gallons) of water into the inner ring.
4. Let the water in the inner ring stand for at least two hours.
Check for leaks in the inner ring seal and repair any that are
found.
OUTER RING
1. Place a peice of plywood from the outer ring crate on the
ground between the inner and outer ring. Place a bucket
(12/87)
F-8
-------
on the plywood. Put the end of the hose that is to used to fill
the rings into the bucket.
2. Slowly fill the rings at a rate of approximately 10 gpm.
3. Should a leak occur, repair it by pushing down on the grout
on the inside edge of the outer ring first, then pressing down
on the grout along the outer edge.
5. When the water level is above the top port on the inner ring,
use a board or shovel handle to gently tap the inner ring to
dislodge air bubbles that are trapped inside. Continue
tapping on the inner ring until bubbles cease to emerge
from the top port.
6. Fill the outer ring until the water level is approximately four
inches above the top port on the inner ring (to a depth of
approximately 12").
7. Remove the buckets from the top of the inner ring.
(12/87)
F-9
-------
INSTALLATION OF FITTINGS
Before installing any fittings into the ports of the inner ring, check that all
the threads are wrapped with teflon tape. Screw fittings in slowly at first and
check that they are not cross-threaded. The threads in the fiberglass can be
stripped easily. Also, do not overtighten the fittings as this may crack the
fiberglass.
Detailed instructions for installing the fittings are given below.
1. Find the plug fitting and install it in one of the lower ports.
2. Find the two fittings with the barbed hose connectors. The
straight fitting goes in the lower port and the elbow fitting
goes into the top port. Saturate the fittings before
connecting them to the inner ring.
3. Cut two lengths of tubing, one 3' long and the other 6' long
4. Place the two pieces of tubing under water to saturate them.
Be sure that all the air is removed from the tubing before
connecting it to the inner ring. Any air remaining in the tube
will be drawn into the inner ring.
5. Push one end of the long peice of tubing onto the top port
fitting. Find the small brass plug fitting and insert it into the
other end of the tubing. This tube is the flush tube and is
used to purge air that has become trapped in the inner ring.
6. Connect the short peice of tubing to the lower port fitting.
This is the inlet tube through which flow measurements are
made. Fix the open end of the tube to one of the cinder
blocks near the wall of the outer ring. Be sure the end of the
tube does not float to the surface and suck in air or fall to the
bottom and suck in mud.
(12/87)
F-10
-------
COVERING THE RINGS
The rings should be covered with a tarp throughout the test. The
primary purpose of the cover is to minimize temperature changes of the water in
the rings caused by wind blowing over the water surface. It also minimizes the
growth of algae by blocking out sunlight. A "Poly Tarp" or an opaque sheet of
plastic can serve as a cover. Place the crate for the outer ring on the top of the
outer ring to support the tarp.
F-ll
-------
OPERATING INSTRUCTIONS
DATA COLLECTION
The data collected during the test includes flow measurements,
temperature, and water level measurements. A sample data sheet is attached
to these instructions. The procedures used to collect these measurements are
discussed below.
FLOW MEASUREMENTS
Measurement of flow during an SDRI test is made using a flexible bag.
The bag is filled water, weighed, connected to a port on the inner ring, and
submerged in the water of the outer ring. Any water that flows out of the inner
ring into the ground will be replaced by an equal amount of water from the bag.
Periodically, the bag is removed and weighed to determine the amount of water
that was lost.
Besides convenience and simplicity, a key feature of using a flexible bag
to measure flow is that a constant pressure difference is maintained across the
wall of the inner ring. Consequently, the inner ring does not expand or contract
when the water level changes in the outer ring.
The flow measurement data is used to construct a plot of infiltration
versus time. For unsaturated soils such as compacted clay liners and covers,
infiltration decreases with time at first, changing rapidly at the beginning of the
test, and then eventually becoming constant with time as the soil becomes
saturated. Consequently, more frequent readings are needed at the beginning
of the test and less frequent readings are need as the flow rate becomes steady.
Typically, flow rates at the beginning of the test (Y three weeks) range
from 1000cc to SOOOcc per day. One reading per day has been found to be
sufficient during this time. When infiltration starts to level out (three to four
weeks) one reading in several days is all that is necessary.
Temperature changes of the water in the inner ring can introduce
significant error in the flow measurements. A 10C change in water temperature
can result in a flow of >*50cc due to volume change of the water in the inner ring
as well as in the inner ring itself. To avoid this problem, the bag should be
disconnected from the inner ring when the water temperature is within +10C of
the water temperature when the bag was connected. This is particularly
important if the flow rate is less than 500 cc/day.
Experience has shown that if the rings are covered and a layer a
polystyrene is used for insulation on the water surface, the temperature of the
water from one morning to the next does not vary by more than 1oC. More
consistent readings are obtained if they are taken on a 24 hour basis and the
(12/87)
F-12
-------
bag is connected and disconnected between 7am and 9am. It should be noted
that the water temperature may change by several degrees during the day but
that these cyclic variatons are only a problem if readings are made at different
temperatures. Allowing the bag to remain connected until at least 1000cc of
flow has occurred also helps to minimize the effect of temperature changes on
the measurement of infiltration rate.
The bag should never be allowed to empty when connected to the inner
ring. When the bag empties, a suction will develop in the inner ring and it may
jepoardize the seal. The most likely time that the bag will empty is at the
beginning of the test when flow rates are not known. For this reason, the bag
should be checked often when first connected. An initial reading should be
made after several hours so that a flow rate can be calculated and an estimate
of when the bag will empty can be made.
It should be noted that it is not necessary to have the bag connected to
the inner ring continuously. If the flow rates are high, (>3000 cc/day) it may be
more convenient to connect the bag up to the inner ring for several hours a day
and let the inlet tube open in the outer ring for the remainder of the time.
Whether the inlet tube is connected to the bag or open to the outer ring does not
affect the infiltration rate. Just be sure if the tube is left open that it is propped in
such a way that it does no suck in air or soil. If it is desired to measure flows
greater than 3000 cc/day, a tee fitting has been provided so that two bags can
be connected to the inlet tube at once.
Detailed instructions for using the bag given below.
Filling the bag.
1. Fill a bucket or a 5 gallon water jug with water and allow to
stand for 24 hours to degas.
2. Cut a peice of flexible tubing long enough to reach from the
bottom of the jug or bucket to a flexible bag laying next to it.
3. Connect the tube to the valve on the bag and siphon water
from the jug into the bag until it is filled.
4. Lift the bag above the water surface in the jug. Hold the
bag with the inlet port at the top and squeeze it to remove
all the air. Squeeze the bag long enough to force the air
out of the tube and then lower the bag so that water will flow
back into it. Repeat this process until all the air is removed.
5. Once all the air is removed, fill the bag slightly less than full
and shut the valve. Avoid completely filling the bag so that
the water in it is under peressure.
(12/87)
F-13
-------
6. Dry the bag and valve thoroughly. If small amounts of flow
are expected (20 cc or less) then be sure that the tube
connector remains full of water.
7. Weigh and record the initial weight of the bag to the nearest
gram.
Connecting the ha? to the inner ring.
1. Connect the bag to the inlet tube as follows. Lower the bag
into the water of the outer ring. Orient the valve so that the
tube connector is pointed up. Flick the tube connector so
that any entrapped air bubbles will be removed from it. It is
important that no air bubbles are present in the tube
connector or bag as they will be drawn into the inner ring or
may even block the flow of water from the bag to the inner
ring. With the bag completely submerged push the tube
connector into the inlet tube. Lay the bag flat on the cinder
blocks. Be sure to position the valve so that it is not folded
back onto the bag and possibly pinching off the flow path.
2. Start flow measurments immediately as follows. Use the
attached data sheet and record the date and time next to
the initial weight of the bag. Carefully open the valve and
allow flow to occur.
3. Periodically determine the amount of flow that has occurred
as follows. Carefully close the valve and disconnect it from
the inlet tube. Be sure to close the valve before handling
the bag. Also, be sure to prop up the open end of the inlet
tube for the reasons mentioned previously. Record the date
and time that the valve was closed . Remove the bag from
the inner ring, dry it thoroughly, and record its weight. As
before, make sure that the tube connector is filled with water
to be consistent. Subtract the final weight from the initial
weight to obtain the amount of flow that has occured.
4. Refill and reweigh the bag if necessary and connect it to
the inner ring. Always check to see that the valve on the
bag or the inlet tubing has not become clogged. With time,
algae may grow in the tube. If this is the case then the tube
should be cleaned or replaced.
Two bags have been supplied. If flow rates are greater than 3000 cc/day,
both bags can be connected to the inner ring at the same time by using the tee
fitting(Fig. 5) that has been supplied. If the flow rate is less than 3000 cc/day,
the extra bag can be filled and weighed in advance so that it can be connected
(12/87)
F-14
-------
to the inlet tube when the other is removed. By doing this, only one trip to the
ring is needed to take a reading.
When connecting a bag to the inner ring, be sure that the valve is closed.
If the bag is accidentally lifted out of the water with the valve open, it is possible
to lift the inner ring out of the ground or rupture the seal. Each inch of head of
water produces an uplift force of about 125 pounds on the inner ring, so holding
the bag several inches above the water level with the valve opened can easily
lift the inner ring out of the ground.
WATER LEVEL
The infiltration rate varies with the depth of the water level in the outer
ring. For this reason, the water level should be recorded each time a flow
measurement is made. Water should be added to the outer ring occasionally in
order to keep the water level to within ±1 inch of the initial level. A scale taped
to the inside wall of the outer ring makes it convenient to monitor the water level.
TEMPERATURE
The temperature of the water in the rings should be monitored closely for
reasons discussed previously. If low flow rates are anticipated (<25 cc/day) and
large temperatue changes expected, it is recommended that a thermistor be
installed in the inner ring.
If temperature is monitored with a thermometer, then measurments need
to be made as close to the inner ring as possible. The recommended
procedure is to put the thermometer in a soda can and then place the can on
the ground next to the inner ring. Remove both the can and the thermometer to
take a reading. The water in the can should remain at the same temperature as
the water near the inner ring long enough to take a reading.
12/87)
' F-15
-------
PURGING AIR FROM INNER RING
During the test, it is possible that air may rise out of the soil and become
trapped in the inner ring. This air should be purged from the inner ring and an
estimate of its volume made. If the volume is significant (>20% of flow since the
last time the ring was purged) the infiltration rate should be corrected to account
for it.
The procedure for purging the inner ring of air is described below.
1. Disconnect bag inlet tube. Use a board or shovel handle
and gently tap on the inner ring to get the air bubbles to rise
to the flush port.
2. Lift the flush tube out of outer ring and lay end of tube on
the ground. The end of the tube needs to be below the
water level so that water can be siphoned out of inner ring.
3. Remove plug from end of flush tube. Water and air if
present will start to flow out of inner ring. If air completely
fills the tube, the syphon effect will be lost. If this happens,
submerge end of tube in water of outer ring and work air out
of tube. Once the tube is saturated, place plug in end of
tube, lift tube out of ring and place on ground. Remove the
plug and allow water to flow from end of tube, (if
tensiometers are being used, the hand pump can be used
instead to restart the siphon)
4. Allow water to flow from end of tube until air ceases to
emerge from inner ring. Replace plug in end of flush tube
and place tube back into outer ring.
found.
5. Wait at least 30 min. before taking any flow measurements.
Purge the inner ring on a weekly basis until no significant amount of air is
(12/87)
F-16
-------
DATA REDUCTION
INFILTRATION
Infiltration (I) can be determined as follows:
I = Q/(At)
where:
I = infiltration (cm/sec)
Q = volume of flow (cm3)
A = area of flow (cm2)
t = time interval in which Q was determined
(sec)
HYDRAULIC CONDUCTIVITY
Hydraulic conductivity (k) in the saturated zone can be determined as
follows:
k = Q/(iAt)
where:
(sec)
Q = volume of flow (cm3)
A = area of flow (cm2)
t = time interval in which Q was determined
i = gradient
meausured
Ah = head loss
AS = length of flow path for which 4 h is
since-
then:
I = Q/(At)
k = l/i
Therefore, if the gradient is known, k can be determined. A suggested
method for determining i and k in the saturated zone beneath the infiltrometer is
illustrated in Fig. 6. The head loss between two points in the saturated zone is
defined as the difference in water levels of piezometers installed at those
points. If piezometers are installed at the ground surface and at the wetting
front, the difference in water levels would be:
Ah = H + D
F-17
-------
where:
H = depth of water in outer ring
D = depth to the wetting
The pore pressure is assummed to be zero at the wetting front. The
length of the flow path is D, and i becomes:
i = (H+D)/D
The position of the wetting front can be determined using one of the
following methods. The simplest is the rod method. This method makes use of
the fact that the soil softens as the wetting front moves through it. The position of
the wetting front is located then by pushing a small diameter rod into the ground
between the inner and outer ring and noting when there is an increase in
resistance. The resistance will increase when the tip of the rod starts to
penetrate the soil just beneath the wetting front. This method works well when
there is a distinct difference in the strength of the saturated soil compared to the
unsaturated soil.
A second method for determining the position of the wetting front is to
use tensiometers. A schematic of a tensiometer is shown in Figure 7. It
consists of a sealed plastic tube with a porous tip on one end and a vacuum
gage on the other. The tube is filled with water and then sealed. Installation
involves first augering a hole in the test pad, slightly less in diameter than the
tube, and then pushing the tensiometer into the hole. If the soil is unsaturated
and there is good contact between the tip and the surrounding soil, water will be
drawn out of the tube and the gage will register a suction. As the wetting front
passes the the tip, the suction will decrease and water will reenter the
tensiometer until the suction goes to zero.
It is recommended that nine tensiometers be used, three at each depth of
6", 12", and 18". A suggested layout for the tensiometers is shown in Fig 8.
Augering a hole and pushing the tensiometer in place is preffered to forming a
hole by driving a pipe into the ground. Driving a pipe may crack the soil and
open up flow channels. A schematic of an augering device is shown in Fig. 9.
The tensiometers should be filled and saturated after they have been installed.
(12/87)
F-18
-------
tensiomete
grout
inner ring f|ush
V. \ port
inlet
port
:test jaad
Figure 1. Schematic Of A Sealed-Double Ring Infiltrometer Installed On
Test Pad
Figure 2. Orientation Of Panels For Assembly Outer Ring.
F-19
-------
Figure 3. Top View Of SDRI Showing Cable Pattern
outer ring
berm of loose soil
Figure 4. Berm Of Soil On Outside Of Outer Ring
F-20
-------
inner ring
tubing
bag
iULi
cinder block
valve' /
tubing
)
tee fitting
Figure 5. Arrangement Of Two Bags Connected To Inner Ring
H + D
vKwv. X^ •> X-
Figure 6. Diagram With Parameters Needed To Calculate Gradient
F-21
-------
cap
water_
column
porous
tip
•vacuum
gage
plastic
tube
Figure 7. Schematic Of A Tensiometer
Figure 8. Top View Of SDRI Showing Layout Of Tensiometers
F-22
-------
electric drill
3/8" rod
tripod
Figure 9. Set-up For Installing Tensiometer
F-23
-------
Page of
D.
Pro]
Innei
Oute
Linei
Datfi
ATA FORM FOR SDRI TEST
cct • i •
r ring in!
r ring in
• thicknes
Initial
lime
(cjppj
fo:
fo:
>s (cm) :
Final
Time
(«?pp)
t
Interval of
Time
(<;pr)
Initial
Wt. of Bag
(gram<;)
1 =
Q =
t = i
A = i
Final Wt.
of Bag
(arams)
1 - Q/(At)
infiltration (cm/sec)
quantity of flow (ml)
nterval of time (sec)
area of inner ring (cm
Q
Quan. of
Flow
(ml)
1
Infiltra-
tion
(cm/sec)
?)
Temp.
(C)
Water
Depth
(in)
NOTES:
-------
Page of
DATE
TIME
PRO
TENSIOMETER
TENSIOMETER READING - CENTIBARS
DEPTH - 6"
GROUP 1
GROUP 2
GROUPS
AVG.
DEPTH - 12"
GROUP1
.IFHTr
TYPE-
GROUP 2
GROUPS
AVG.
DEPTH -18"
GROUP 1
GROUP 2
NOTES:
GROUP 3
AVG.
i
to
-------
APPENDIX G
-------
Preprint: Proceedings, GEOTECHNICAL PRACTICE FOR WASTE DISPOSAL, ASCE
Specialty Conference, University of Michigan, Ann Arbor,
Michigan, June 15-17, 1987.
Earthen Liners for Land Disposal Facilities
David E. Daniel, M. ASCE*
Abstract
Proper construction of compacted earthen liners requires
special attention to construction details and quality assurance.
Moisture content and weight of roller are probably the two most
important construction variables. Attack of liners by chemicals is a
major concern only for relatively concentrated chemicals. With good
practice, clay liners can function successfully.
Introduction
The purpose of this paper is to identify the current state of
knowledge and engineering practice for design, construction, and
testing of earthen liners. The paper is divided into discussions of
types of liners, materials, construction of compacted liners,
verification of in-situ properties, degradation of liners, case
histories, and conclusions.
Types of Liners
Earthen liners may be man-made or naturally occurring. Man-
made liners may consist of a horizontal liner, an inclined liner, or
a cover over a landfill (Fig. 1) . Man-made liner systems are
typically composed of hydraulic barriers and drains (Fig. 1). It is
not uncommon to employ a mix of materials, including clayey soils and
geomembranes for barriers, and sand, gravel, or geosynthetics for
drains. Natural earthen liners are formed by aquitards or
aquicludes. Wastes may be buried wholly within a natural earthen
liner (Fig. 2a), partially within a natural liner (Fig. 2b), or above
but not within a natural liner (Fig. 2c).
Materials
Man-Made Liners
Because the main purpose of a liner is to minimize leakage of
liquid through the liner, the hydraulic conductivity (k) of the liner
is its most important characteristic. The plasticity index and clay
content of a soil are often regarded as key index properties. The
author has assembled data from his files on 15 soils compacted in the
laboratory following ASTM Standard D698, Method A. All materials
were compacted 0 to 2% wet of optimum and then permeated with water
in University of Texas laboratories. The k's of the test specimens
"Associate Professor, Dept. of Civil Engineering, The University of
Texas, Austin, Texas 78712.
G-l
Daniel
-------
Compocted
Sidewoll
Liner
(Horizontal
Lifts)
Compacted
Cover
Compacted
Bottom Liner
Leachote Collection Zone-" ..•':•.
Primary Line r~=
Leak Detection ^~--^' • ••-•'•'•'
Secondary Liner'
Compacted
Sldewall Liner
(Lifts Parallel
to Slope)
Figure 1. Types of Compacted Liners
>L^ Compacted
.'••'• !•.' Liner •'.
^--Cutoff wail.; ..' :;.••.
Figure 2. Examples of Natural Liners
G-2
Daniel
-------
are plotted as a function of plasticity index (Pi) in Fig. 3. While
there is a trend for decreasing k with increasing PI, the trend is
weak, especially for Pi's below 40%.
Clay content can be important, but only for soils with less
than about 20% clay by weight. The sensitivity of k to clay content
is illustrated in Fig. 4, which shows that one need only add a small
amount of bentonite to silty sand to achieve low k.
There are practical reasons to prefer a soil of low plasticity
over a highly plastic clay. Soils with low plasticity are often
easier to mix, hydrate, and homogenize in the field and tend to be
less susceptible to desiccation cracking.
Natural Liners
For natural liners, the continuity, overall hydraulic
conductivity, and long-term integrity of the materials are critical.
Attention should be focused on looking for hydraulic defects, such as
sand seams, cracks, or fissures. Thick sequences of unweathered,
unfissured, unfractured clayey soil have the highest probability of
forming continuous liners of low hydraulic conductivity.
Construction of Compacted Clay Liners
Objectives
Mitchell, Hooper, and Campanella (1965) showed in the
laboratory that compaction water content, method of compaction, and
compactive effort have major influences on k of compacted clay (Fig.
5) . Numerous laboratory studies have subsequently verified that in
order to achieve low k, the soil should be compacted wet of optimum
water content using a high level of kneading-type compactive effort.
There are two schools of thought about why compaction wet of
optimum produces low k. One, described by Lambe (1958) among others,
suggests that soil particles are arranged in a flocculated pattern
when the soil is compacted dry of optimum and in a dispersed pattern
for wet-side compaction. A dispersed arrangement of particles leads
to low k, according to this theory. The second school of thought,
pioneered by Olsen (1962), is that the uncompacted soil consists of
aggregates of soil particles, which Olsen called clusters but which
others have called peds or clods. According to this theory, after
the soil is compacted, a few inter-clod voids or macro-pores will
exist such that most of the permeating liquid flows around rather
than through the remnant clods. Wet-side compaction produces low k,
according to this theory, because the soft (wet) clods are remolded
during compaction and the volume and continuity of inter-clod pores
are minimized.
There may be a certain degree of validity to both theories.
However, in the author's experience, the fate of inter-clod pore
spaces is critical for achieving low k. If the size and continuity
.of inter-clod pores are minimized, low k will result (Garcia-
Bengochea, Lovell, and Altschaeffl, 1981; and Daniel, 1984). The
ideal situation is small, soft, weak clods of clay that are easily
remolded, and compaction with a heavy roller that effectively remolds
and melds the clods together.
G~3 Daniel
-------
- 10
o
0)
\
^o
>s
*-
'>
tj
c
o
(J
o
"5
o
T3
I
10 20 30 40 50 60
Plasticity Index (%)
Figure 3. Effect of Plasticity Index on the Hydraulic
Conductivity of Laboratory-Compacted Soils
04 8 12 16 20 24
Percent Bentonite
Figure 4. Effect of Bentonite on Hydraulic Conductivity
of Compacted Silty Sand
G-4
Daniel
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NCREASMB
COMPACTIVE
EFFORT
OPTIMUM
\MOTER
CONTENT
INCREASMG COMP*CTTVE EFFORT
ill i i i i i i
12
16 • 20
MOLDKO VHCTEB CONTENT (%)
Figure 5. Influence of Molding Water Content and Compactive
Effort on Compacted Silty Clay (from Mitchell,
Hooper, and Campanella, 1965)
Construction Practices
It is logical to expect that compaction equipment that is most
capable of eliminating inter-clod voids is best. Heavy, footed
rollers, with fully-penetrating feet (Fig. 6), passed over tolerably
thin lifts of soil with a sufficient number of passes, are ideal.
However, with extremely soft clods of soil, a heavy roller with
fully-penetrating feet will likely become bogged down, and a roller
with shorter feet would be better. Also, fully-penetrating feet with
a small contact area may not work well for sand-bentonite mixtures
because the "holes" left by the feet may not be properly sealed. In
several instances in which light-weight, footed rollers were used,
high k was observed (Day and Daniel, 1985a; and Rogowski, 1986) . The
only case history in the literature known to the author in which low
k (2 x 10~8 cm/sec) was demonstrated by in-situ measurements involved
clay that was compacted by extremely heavy (more than 66,000 Ibs or
293 kN) footed rollers (Reades et al., 1986). Tests indicated that
lighter footed rollers would not produce such low k's. The engineer
who simply specifies a "sheepsfoot roller" without paying attention
to the weight of the roller is asking for trouble.
G-5
Daniel
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Fully-Penetrating Feet =
CJ
Loose Lift
of Soil
Compacted Lift
/ / x / / /
Partly-Penetrating Feet:
Loose Lift
of Sol!
Compacted Lift
Figure 6. Examples of Fully- and Partly-Penetrating
Feet on Footed Rollers
Homogenization and hydration of the soil are also critical;
thorough mixing is essential. If water is to be added to the clay,
time must be allowed for the soil to absorb the water and hydrate
fully; otherwise, the clods will be wet on the outside but dry and
hard on the inside. The size of clods should be minimized by disking
or pulverizing the soil prior to compaction.
Construction Quality Assurance
Construction quality assurance (CQA) for compacted clay liners
is discussed by Gordon et al. (1984), Spigolon and Kelley (1984), and
EPA (1985) . The importance of thorough CQA by qualified people
cannot be overemphasized. However, many CQA programs place too much
emphasis on dry density and too little emphasis on moisture content,
compactive effort, and the elimination of inter-clod voids. While
density is a key indicator of stiffness and strength for select
fills, it is not a very good indicator of hydraulic conductivity for
clay liners. The application of more compactive effort to a soil that
is wet of optimum can significantly reduce k without changing the
density measurably (Mitchell et al., 1965). The destruction of
inter-clod voids may require a great deal of compactive effort and
remolding of the soil, but the corresponding reduction in density can
G-6
Daniel
-------
be subtle. The degree of saturation is a good indicator of the
compactive effort for soils compacted wet of optimum.
Some engineers rely greatly upon laboratory hydraulic
conductivity tests performed on "undisturced" samples obtained from
completed lifts of compacted clay. Laboratory k tests can produce
misleading results because: (1) the process of pushing a sampling
tube into the soil may compress air-filled macro-pores and cause
large reductions in k; (2) the impermeable sidewalls of the
laboratory permeameter may cut off certain avenues of flow
(horizontal seepage) that could be significant in the field; and (3)
the soil sample may be too small to account properly for inter-clod
pores or other secondary features. However, laboratory k tests are
useful for many purposes, e.g., as one of many tools in a
comprehensive CQA program, for defining the influence of overburden
stress on k, for determining the relationship between k and degree of
saturation, and for studies of waste/soil interactions.
Test Pads
The construction of a test pad prior to building a full-sized
liner has many advantages. By constructing a test pad, one can
experiment with compaction water content, construction equipment,
number of passes of the equipment, lift thickness, etc. Most
importantly, though, one can conduct extensive testing, including CQA
testing and in-situ hydraulic conductivity testing, on the test pad.
It is crucial that construction criteria and CQA tests be related to
in-situ hydraulic conductivity.
It is recommended that the test pad have a width of at least 3
construction vehicles, and an equal or greater length. The pad
should ideally be the same thickness as the full-sized liner, but the
trial pad may be thinner than the full-sized liner. (The full-
thickness liner should perform at least as well as, and probably
better than, a thinner test section because defects in any one lift
become less important as the number of lifts increases). The in-situ
k may be determined in many ways, although direct ponding with an
underdrain system, supplemented by surface infiltration tests, is the
recommended technique (Daniel and Trautwein, 1986). The pad may be
covered with gravel over a limited area to aid in establishing the
relationship between k and overburden stress (Fig. 7).
Verification of In-Situ Hydraulic Conductivity
Compacted Clay Liners
There are several options for verifying k of compacted clay
liners. One is to extract relatively undisturbed samples of soil
from the liner and to measure k in the laboratory. Daniel (1984) and
Day and Daniel (1985a) found that laboratory tests yielded k's that
were much too low. Reades et al. (1986) found good agreement between
lab k's and field performance, but extraordinary care was taken in
establishing construction criteria. For homogeneous soils, one would
expect lab k's to be the same as field k's, but for liners containing
hydraulic defects (cracks, fissures, macro-pores, zones of variable
material, etc.), small samples are unlikely to be representative of
in-situ conditions.
G_7 Daniel
-------
Collection
Pit
Gravel to Load Clay
to Evaluate Effect of
Overburden Stress-
Compacted
Clay
Sealed
Infiltrometor
'JToColectlor,
3' Pit
Collection Pan Lysimeter
Underdraln
Geomembrane
Figure 7. Hydraulic Conductivity Tests on Test Pad of Compacted
Clay Involving Sealed Infiltrometer, Pan Lysimeters,
and a Full Underdrain
Daniel and Trautwein (1986) described the options for in-situ k
testing of compacted earthen liners. The available techniques are a
borehole method developed by Boutwell (unpublished), porous probes
such as the one described by Torstensson (1984), the air-entry
permeameter (Bouwer, 1966), lysimeter pans (Reades et al., 1986),
underdrains beneath liners with water ponded on the liner (Day and
Daniel, 1985a), single-ring infiltrometers (Nolan, 1983; and Day and
Daniel, 1985b), double-ring infiltrometers (Day and Daniel, 1985b),
and sealed double-ring infiltrometers (Daniel and Trautwein, 1986).
All testing techniques have advantages and disadvantages. However,
in the author's view, testing a large volume of soil is the most
important consideration, and ring infiltrometers, pan lysimeters, and
underdrains do this best.
Natural Linera
In-situ hydraulic conductivity of natural liners is best
evaluated by a combination of geochemical measurements, hydrogeologic
analyses, and in-situ k tests. An excellent example of a
comprehensive study of k of a natural stratum of clay was presented
by Keller, van der Kamp, and Cherry (1986). More information on in-
situ k tests for natural clays may also be found in Daniel and Olson
(1981), and Electric Power Research Institute (1985).
Modes of Degradation of Liners
Attack of Soil by Waste
Waste liquids may attack and effectively destroy earthen
liners. It is convenient to consider acids and bases, neutral
inorganic liquids, neutral organic liquids, and leachates separately.
Testing protocols have been described by Bowders et al. (1986).
Acid.q and Baaea . Strong acids and bases can dissolve solid
material in the soil, form channels, and increase k. Some acids,
e.g., hydroflouric and phosphoric acid, are particularly aggressive
G-8
Daniel
-------
and dissolve soil readily. Concentration of acid, duration of
reaction, liquid-solid ratio, type of clay, and temperature are also
important variables (Grim, 1953).
When concentrated acid is passed through clayey soil, the
results depicted in Fig. 8 are commonly observed. Initially, there
is a drop in k that is caused by precipitation of solid matter from
the permeating liquid as the acid is neutralized by the dissolved
soil. The precipitates plug the pores a short distance into the
specimen. With continued permeation, fresh acid enters the soil,
redissolves the precipitates and eventually causes an increase in k.
Soils have a high capacity to buffer acid; many pore volumes of flow
are usually needed before the full effect of the acid is observed.
Examples include Nasiatka et al. (1981), Bowders (1985), and Peterson
and Gee (1986) . Soils that are composed primarily of sand, with a
small amount of bentonite, are particularly susceptible to attack by
acids because the small mass of bentonite is readily dissolved
(Nasiatka et al., 1981) . Strong bases may also dissolve soil, but
data are lacking.
Pore Volumes of Flow
Figure 8. Typical Variation in Hydraulic Conductivity
for Sample of Compacted Clay Permeated with
Concentrated Acid
G-9
Daniel
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Ngutralr Tnorygp-ic Liquids. The effects of neutral, inorganic
liquids may be evaluated with the Gouy-Chapman theory (Mitchell,
1976), which states that the thickness (T) of the diffuse double
layer varies with the dielectric constant of the pore fluid (D), the
electrolyte concentration (n0), and the cation valence (v) as
follows:
T a [o/(n0 v2) ] i/2 (1)
For solutions containing mainly water, the dielectric constant of the
liquid is relatively constant, and thus the main parameters are n0
and v. As the diffuse double layer of adsorbed water and cations
expands, k decreases because flow channels become constricted.
Attempts to validate quantitatively the effect of D, n0, and v on k
have generally failed. Qualitatively, however, the Gouy-Chapman
theory explains the observed patterns. Aqueous solutions with few
electrolytes, e.g., distilled water, tend to expand the double layer
and to produce low k. Solutions with monovalent cations, e.g., Na+,
tend to produce lower k than solutions with polyvalent cations, e.g.,
Ca++. A strong (high n0) solution containing polyvalent cations
tends to produce the largest k. Further details and supporting data
are reported by Fireman (1944), Quirk and Schofield (1955), McNeal
and Coleman (1966), and Dunn and Mitchell (1984) .
Neutral. Organic Liquids. Most organic chemicals have lower
dielectric constants than water. Low D tends to cause low T (Eq. 1)
and thus high k. In addition, low-dielectric-constant liquids cause
clay particles to flocculate (Bowders, 1985) and cause the soil to
shrink and to crack (Anderson, 1983; and Quigley and Fernandez,
1985) . This phenomenon is called "syneresis" and the cracks
"syneresis cracks." Numerous studies have shown that organic
chemicals can cause large increases in k (Anderson, 1982; Acar et
al., 1985; Fernandez and Quigley, 1985; Foreman and Daniel, 1986;
and others).
Stress significantly affects interactions between soil and
organic solvents. High compressive stress causes the soil to compact
when a solvent passes through the soil rather than to crack. Thus,
clays perform much better at high compressive stress than low stress
(Fig. 9) when they are permeated with organic liquids.
Clays with high negative charge and high activity are more
susceptible to attack by organic chemicals than clays with low
negative charge (Acar and Ghosn, 1986) . Sodium bentonite is
particularly susceptible to attack.
Dilute organic liquids do not tend to alter k significantly.
If a small amount of low-dielectric-constant liquid, e.g.,
trichlorethylene (D=3), is mixed with water, the dielectric constant
of the mixture is only slightly less than that of water (80). Tests
have indicated that the dielectric constant must be less than 30 to
50 for k to increase. Experience indicates that k of clay soils is
not likely to be adversely affected by an organic liquid if (1) the
solution consists of at least 50% water, and (2) there is no
separation of phases, i.e., all of the organic liquid is dissolved in
the water and none exists as a separate phase.
G-10 Daniel
-------
«
e
o
c
o
o
o
10
-5°
Vertical Effective Stress (kPa)
20 40 60 80 100 120
„
io'6r
10
-7
10
-8
10
-9
Figure 9. Influence of Effective Stress on Compacted Clay
Permeated with Methanol in a Consolidation-
Cell Permeameter
Actual Landfill Leachates. Griffin and Shimp (1978) report
data for municipal solid waste while Daniel and Liljestrand (1984)
tested leachate from hazardous industrial waste. Both investigators
found steady or decreasing k with time. Dilute liquids appear to be
incapable of increasing k of most soils.
Desiccation
Desiccation can crack clays and increase k. Boynton and Daniel
(1985) found that desiccated clays undergo some self-healing upon
wetting but the self-healing is not complete unless significant
compressive stress is applied to close the cracks. Boynton and
Daniel also found that cracks can penetrate several inches into
compacted clay in less than 24 hours. Kleppe and Olson (1985) found
that -the susceptibility of compacted clay to desiccation cracking
increases with increasing compaction water content, increasing
plasticity index, and increasing clay content, but that dry density
has little effect. Daniel and Trautwein (1986) performed in-situ k
tests on two sections of a landfill cover. The section that had been
exposed to dry weather for several days had a ten-fold larger k than
the section that was soaked by rain immediately after construction.
G-ll
Daniel
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There is no doubt that desiccation can damage liners. Accordingly,
liners should be protected during and after construction by frequent
moistening or by a protective covering.
Frost Action
Compacting frozen soil for clay liners is bad practice because
inter-clod pores cannot be eliminated with hard, frozen clods. Not
much is known about the effects of freezing on a completed lift or a
completed liner, but prudence would dictate that freezing of a liner
be avoided because the soil might shrink and crack.
Case Histories
Compacted Liners
A number of cases in which the actual k of compacted clay
liners has been greater than 1 x 10~7 cm/sec have been reported
(Table 1) . To the author's knowledge, only one case (the Keele
Valley Landfill, Reades .et al., 1986) of in-situ k less than 1 x 10~7
cm/s has been reported. At Keele Valley, several trial pads were
built. When an extremely heavy, footed roller was used, low k was
achieved. Keele Valley provides several important lessons: (1)
extraordinary care and CQA may be needed to achieve a liner with low
k; (2) test pads are extremely useful in establishing construction
practices; (3) very heavy compaction equipment is desirable; and (4)
performance monitoring which shows how well a liner is working is
extremely useful.
There are few case histories of chemical attack. Brown, Green,
and Thomas (1983) found very high k in prototype liners exposed to
organic solvents.
Natural Liners
There are only a few case histories of performance of natural
liners (Table 2) . The sites in Texas and in Wilsonville, Illinois,
were designed based on laboratory k tests; in-situ k tests showed
that the liners were much more permeable than expected. Thick,
unfractured tills near Sarnia, Ontario, seem to have low k and to be
working well. The main lesson from the case histories is to exercise
great care in evaluating k of natural liners.
Conclusions
Compacted clay liners with low hydraulic conductivity can be
constructed, but great care must be taken in thoroughly mixing and
homogenizing the soil. Time should be allowed for the soil to
hydrate or dehydrate evenly if water is added or removed. The clods
of clay should be sufficiently small and soft to be remolded during
compaction. The compaction equipment should compress voids between
clods and destroy the continuity of inter-clod voids by remolding the
soil. Emphasis should be given to using heavy rollers; simply
specifying a sheepsfoot roller may not ensure that an adequate roller
has been used. Lifts of compacted clay should be bonded together
properly. Construction quality assurance is critical, but
specifications with heavy emphasis on dry density may be ineffective.
Lifts of compacted clay, and the completed liner, should not be
allowed to freeze or to desiccate significantly.
G-12 Daniel
-------
TABLE 1. CASE HISTORIES OF COMPACTED CLAY LINERS
Location of Site
Central Texas
Northern Texas
Nature of Liner
2-acre (0.8 ha) Liner for
Impoundment; l-ft-(30-cm)
Thick Liner Built of Local
Clay Soil
25-acre (10 ha) Liner for
Impoundment; 8-in-(20-cm)
Thick Liner Built from
Sand/Bentonite Mixture
Actual
Field k
(cm/sec)
4 x 10"5
(originally)
5 x 10~6
(Reconstructed)
3 x
10~6
Reference and Comments
Daniel (1984). Original liner may have
desiccated somewhat. Reconstructed
liner not subjected to desiccation. Poor
CQA. Liner retained fresh water.
Daniel (1984). Virtually no CQA.
retained slightly saline water.
Liner
I
I—I
U)
Southern Texas
Northern Mexico
1-acre (0.4 ha) Liner for 1 x 10~5
Impoundment; Liner was 2-ft-
(30-cm) Thick and Built
with Local Clay Soil
Test Liner 50x50x0.5m Ix 10~6
and Built with Local Clay
Soil
Daniel (1984). Liner retained brine
solution. Little CQA.
Auvinet and Espinosa (1981) and Daniel
(1984). Good CQA. Liner tested with fresh
water.
o
fu
Texas A&M
University
University of
Texas at Austin
Prototype Liners; Each Proto-
type Measured 1.5 x 1.5 x
0.15 m; Soils Consisted of
Kaolinite, Mica, and
Bentonite Blended with Sand
Two Prototype Liners; Each
Liner Measured 20 x 20 x
0.5 ft (6x6x0.15m) and
Was Built of Local Clay Soil
1 x 10~6
to
1 x 10~5
4 x 10~6
and
9 x 10~6
Brown, Green, and Thomas (1983). Good CQA.
Soil compacted with hand-operated equipment
Liquids were xylene and acetone wastes.
Day and Daniel (1985a). Good CQA , although
moisture content varied more than desired.
Soil compacted with hand-operated equipment.
-------
TABLE 1. CASE HISTORIES OF COMPACTED CLAY LINERS (Continued)
Location of Site
Confidential
Midwestern U.S.
Western U.S.
I
I-"
*>.
a
PI
H-
(D
Western U.S.
Northeastern U.S.
Toronto, Ontario,
Canada
Actual
Field k
(cm/sec)
2 x 1CT6
2 x 1CT7
Nature of Liner
100-acre (40 ha) Pond for
Wastewater; 1-ft- (30-cm)
Thick Liner Built of Local
Sandy Clay
5-acre (2 ha) Pond for Waste-
water; 5-ft- (1.5-m) Thick
Liner Built of Local Clayey
Soil
3 Impoundments; 5-ft- (1.5-m) Not
Thick Liners Built of Local Documented
Clayey Soil
6 Impoundments, 3-ft- (90-cm) 1 x 10 7
Thick Liners Built from Local to
Clay Stone 4 x 10"7
2 Landfills, 1.5- to 2-ft Not
(46 to 60 cm) Thick Liners Documented
16-acre (4 ha) Municipal 2 x 10~8
Waste Landfill; 1.2-m
Thick Liner Built of Local
Clayey Soil
Reference and Comments
Unpublished case history from author's
files. Extensive CQA.
Unpublished case history from author's
files. Extensive CQA. Possible effects from
organic solvents.
RTI (1986). Good CQA. After 4 yrs of
service, no waste in leak detection zone
beneath 2 liners. Waste appeared in leak
detection zone beneath one of the liners
after 3 mos of service, but this liner had
been left exposed and unprotected for 6 mos.
RTI (1986). Field performance determined
from volume of liquid collected in leak
collection zones beneath the liners.
RTI (1986). Within one year of operation,
leachate was detected in leak detection
zone beath the liner.
Reades et al. (1986). Keele Valley Landfill.
Performance determined by underdrains, each
15 x 15 m. Excellent CQA. Test pads used
to establish construction criteria.
-------
TABLE 2. CASE HISTORIES OF NATURAL CLAY LINERS
Location of Site
Nature of Liner
Actual
Field k
(cm/sect
Reference and Comments
Sarnia, Ontario
Canada
Wilsonville,
Illinois
Northern Texas
41-m (135-ft) Thick Unfissured,
Medium, Gray, Silty Clay Till;
Two Municipal Waste Landfills
Unknown
130-acre (52 ha) Hazardous
Waste Landfill; Disposal Pit
Underlain by 15 ft (4.5 cm)
of Weathered Till and 20 ft
(6 m) of Unweathered Till
48-acre (19 ha) Impoundment;
Alluvial Clay 50-ft (15-m)
Thick
1 x 10~5
to
2 x 1CT6
(Weathered
Till)
8 x 1CT8
to
9 x ICT7
(Unweathered
Till)
8 x 1CT5
to
1 x 1CT4
Goodall and Quigley (1977). After 6 yrs of
operation, pollutants extended to a depth
of 30 cm (1 ft) in one landfill and 80 cm
(2.6 ft) at a second landfill.
Griffin et al. (1985). Contaminants leaked
from disposal pits via fractures.
Organic solvents may have affected
hydraulic conductivity.
Daniel, Trautwein, and McMurtry (1985).
Massive ground water contamination
developed over 2 decades.
o
(D
H-
(D
-------
Construction criteria for compacted clay are best established
with test pads. The construction criteria can be related to
performance via in-situ measurements of hydraulic conductivity. The
critical quality assurance tests can also be related to performance
on the test pads. The advantages of test pads are so compelling that
the author recommends them for all important projects where the
consequences of an excessively leaky liner are serious.
With natural clay liners, a variety of geochemical,
geohydrological, and engineering tools are available for
investigating the hydraulic integrity of the liner. The literature
shows that in-situ hydraulic conductivity tests are much more
accurate than laboratory tests.
Much is known about the tendency for wastes to attack soil.
Dilute liquids are generally of little concern, but concentrated salt
solutions, organic solvents, acids, and bases can attack clay. Clays
subjected to large compressive stress are much less susceptible to
attack than clays subjected to small stress. Overburden stress also
helps to close macro-pores and to produce low hydraulic conductivity
even if there is no chemical attack.
Clay liners have been maligned by many, perhaps unfairly. The
fact is that some clay liners are performing well. For those that
are not performing well, the cause of poor performance is generally
known and can be traced back to inadequate construction practices or
inaccurate determinations of hydraulic conductivity. With good
practice, mistakes of the past need not be repeated.
REFERENCES
1. Acar, Y. B., and A. Ghosn (1986), "Role of Activity in Hydraulic
Conductivity of Compacted Soils Permeated with Acetone," Proceedings.
International Symposium on Environmental Geotechnology, Allentown,
Pennsylvania, pp. 403-412.
2. Acar, Y. B., Hamidon, A., Field, S. D., and L. Scott (1986),
"The Effect of Organic Fluids on Hydraulic Conductivity of Compacted
Kaolinite," ASTM STP 874, pp. 171-187.
3. Anderson, D. C. (1982), "Does Landfill Leachate Make Clay Liners
More Permeable?", Civil Engineering. Vol. 52, No. 9, pp. 66-69.
4. Auvinet, G., and J. Espinosa (1981), "Impermeabilities of a 300-
Hectare Cooling Pond," ASTM STP 746, pp. 151-167.
5. Bouwer, H. (1966), "Rapid Field Measurement of Air Entry Value
and Hydraulic Conductivity of Soil as Significant Parameters in Flow
System Analysis," Water Resources Research. Vol. 2, No. 4, pp. 729-
738.
6. Bowders, J. J. (1985), "The Influence of Various Concentrations
of Organic Liquids on the Hydraulic Conductivity of Compacted Clay,"
Dissertation, University of Texas at Austin, 219 p.
G-16 Daniel
-------
7. Bowders, J. J., Daniel, D. E., Broderick, G. P., and :-:. M.
Liljestrand (1986)r "Methods for Testing the Compatibility of Clay
Liners with Landfill Leachate,n ASTM STP 886, pp. 233-250.
8. Boynton, S. S.r and D. E. Daniel (1985), "Hydraulic Conductivity
Tests on Compacted Clay," Journal of Geotechnical Engineering, Vol.
11,1 No. 4, pp. 465-478.
9. Brown, K. W., Green, J. W., and J. C. Thomas (1983), "The
Influence of Selected Organic Liquids on the Permeabilicv of Clay
Liners," EPA-6GO/9-83-013, pp. 114-125.
10. Daniel, D. E. (1984), "Predicting Hydraulic Conductivity of Clay
Liners," Journal of Geotechnical Engineering, Vol. 110, No. 2, pp.
285-300.
11. Daniel, D. E., Anderson, D. C,, and S. S. Boynton (1985),
"Fixed-Wall vs. Flexible-Wall Permeameters," ASTM STP 874, pp. 107-
126.
12. Daniel, D. E., and' H. M. Liljestrand (1984), "Effects of
Landfill Leachates on Natural Liner Systems," Report to. Chemical
Manufacturers Association, University of Texas, Geotechnical
Engineering Center, Austin, Texas.
13. Daniel, D. E., and S. J. Trautwein (1986), "Field Permeability
Test for Earthen Liners," Use of In Situ Tests in Geotechnical
Engineering. ASCE, S. P. Clemence (Ed,), pp. 146-160.
14. Daniel, D. E., Trautwein, S. J., Boynton, S. S., and D. E.
Foreman (1984), "Permeability Testing with Flexible-Wall
Permeameters," Geotechnical Testing Journal. Vol. 7, No. 3, pp. 113-
122.
15. Daniel, D. E., Trautwein, S. J., and D. McMurtry (1985), "A Case
History of Leakage from a Surface Impoundment," Proceedings, Seepage
and Leakage from Dams and Impoundments, ASCE, pp. 220-235.
16. Day, S. R., and D. E. Daniel (1985a), "Hydraulic conductivity of
Two Prototype Clay Liners," Journal of Geotechnical Engineering, Vol.
Ill, No. 8, pp. 957-970.
17. Day, S. R., and D. E. Daniel (1985b), "Field Permeability Test
for Clay Liners," ASTM STP 874, pp. 276-288.
18. Dunn, R. J., and J. K. Mitchell (1984), "Fluid Conductivity
Testing of Fine—Grained SOils," Journal of Geotechnical Engineering.
Vol. 110, No. 11, pp. 1648-1665.
19. Electric Power Research Institute (1985), "Field Measurement
Methods for Hydrogeologic Investigations: A Critical Review of the
Literature," EPRI EA-4301, Palo Alto, California.
20. Evans, J. C., and H-Y Fang (1986), "Triaxial Equipment for
Permeability Testing with Hazardous and Toxic Permeants,"
Geotechnical Testing Journal. Vol. 9, No. 3, pp. 126-132.
G-17 Daniel
-------
21. Fernandez, F., and R. M. Quigley (1985), "Hydraulic Conductivity
of Natural Clays Permeated with Simple Hydrocarbons," Canadian
Geot.echnieal Journal. Vol. 22, No. 2, pp. 205-214.
22. Fireman, M. (1944), "Permeability Measurements on Disturbed Soil
Sample," Soil Science. Vol. 58, pp. 337-355.
23. Foreman, D. E., and D. E. Daniel (1986), "Permeation of
•Compacted Clay with Organic Chemicals," Journal o_f Gee-technical
Engineering. Vol. 112, No. 7, pp. 669-681.
24. Garcia-Bengochea, I., Lovell, C. W., and A. G. Altschaeffl
(1979), "Pore Distribution and Permeability of Silty Clays," Journal
of the Geotechnical Engineering Division. ASCE, Vol. 105, No. GT7,
pp. 839-856.
25. Goodall, D. C., and R. M. Quigley (1977), "Pollutant Migration
from Two Sanitary Landfill Sites near Sarnia, Ontario," Canadian
Geotechnical Journal. Vol. 14, No. 2, pp. 223-236.
26. Gordon, M. E., Huebner, p. M., and P. Kmet (1984), "An
Evaluation of the Performance of Four Clay-Lined Landfills in
Wisconsin," Proceedings. Seventh Annual Madison Waste Conference, pp.
399-460.
27. Griffin, R. A., et al. (1985), "Mechanisms of Contaminant
Migration through a Clay Barrier, Case Study, Wilsonville, Illinois,"
U.S. EPA/600-9-85-013, pp. 27-38.
28. Griffin, R. A., and N. F. Shimp (1978), "Attenuation of
Pollutants in Municipal Landfill Leachates by Clay Minerals," U. S.
EPA, Report EPA-600/2-78-157.
29. Grim, R. E. (1953), Clay Mineralogy. McGraw-Hill, New York, 384
P-
30. Keller, C. K., van der Kamp, G., and J. A. Cherry (1986),
"Fracture Permeability and Groundwater Flow in Clayey Till near
Saskatoon, Saskatchewan," Canadian Geotechnical Journal. Vol. 23, pp.
229-240.
31. Kleppe, J. H., and R. E. Olson (1985), "Desiccation Cracking of
Soil Barriers," ASTM STP 874, pp. 263-275.
32. Lambe, T. W. (1958), "The Structure of Compacted Clay," Journal
of the Soil Mechanics and Foundations Division,. ASCE, Vol. 84, No.
SM2, pp. 1-34.
33. McNeal, B. L., and N. T. Coleman (1966), "The Effect of Solution
on Soil Hydraulic Conductivity," Soil Science Society of America
Proceedings. Vol. 30, No. 3, pp. 308-312.
34. Mitchell, J. K. (1976), Fundamentals of Soil Behavior. John
Wiley & Sons, New York, 422 p.
35. Mitchell, J. K., Hooper, D. R., and R. G. Campanella (1965),
"Permeability of Compacted Clay," Journal of the Soil Mechanics and
Foundations Pi vi .si on r ASCE, Vol. 91, No. SM4, pp. 41-65.
G-18 Daniel
-------
36. Nasiatka, D. M., Shepherd, T. A., and J. D. Nelson (1981), "Clay
Liner Permeability in Low pH Environments," Proceeding.q. Symposium on
Uranium Mill Tailings Management, Colorado State University, Fort
Collins, Colorado, pp. 627-645.
37. Nolan, T. W. (1983), "Evaluation of the Single-Ring
Infiltrometer for Measuring Hydraulic Conductivity of Clay Liners,"
M.S. Thesis, Syracuse University, 94 p.
38. Olsen, H. W. (1962), "Hydraulic Flow through Saturated Clays,"
Clays and Clay Minerals. Vol. 9, pp. 131-161.
39. Olson, R. E., and D. E. Daniel (1981), "Measurement of the
Hydraulic Conductivity of Fine-Grained Soils," ASTM STP 746, pp. 18-
64.
40. Peterson, S. R., and G. W. Gee (1986), "Interactions between
Acidic Solutions and Clay Liners: Permeability and Neutralization,"
ASTM STP 874, pp. 229-245.
41. Quirk, J. P., and R. K. Schofield (1955), "The Effect of
Electrolyte Concentration on Soil Permeability," Journal of Soil
Science. Vol. 6, No. 2, pp. 163-178.
42. Reades, D. W, Poland, R. J., Kelly, G., and S. King (1986),
Discussion, Journal of Geotechnical Engineering, in press.
43. Research Triangle Institute (1986), "Design, Construction, and
Evaluation of Clay Liners for Hazardous Waste Facilities," Draft
Technical Resource Document, EPA-530/SW-86-007.
44. Rogowski, A. S. (1986), "Hydraulic Conductivity of Compacted
Clay Soils," P roceedings . Land Disposal, Remedial Action,
Incineration, and Treatment of Hazardous Waste, U. S. EPA,
Cincinnati, Ohio, in press.
45. Spigolon, S. J., and M. F. Kelley (1984), "Geotechnical Quality
Assurance of Construction of Disposal Facilities," EPA-600/2-84-
040, 181 p.
46. Torstensson, B. A. (1984), "A New System for Ground Water
Monitoring," Ground Water Monitoring Review. Vol. 4, No. 4, pp. 131-
138.
47. U.S. EPA (1985), "Construction Quality Assurance for Hazardous
Waste Land Disposal Facilities," Public Comment Draft, EPA/530-SW-85-
021.
G-19
-------
APPENDIX H
-------
LABORATORY TESTING OF GEOSYNTHETICS AND PLASTIC PIPE
FOR DOUBLE-LINER SYSTEMS
by
Henry E. Haxo, Jr.
Muriel J. Waller
Matrecon, Inc.
Oakland, CA 94623, U.S.A.
to be
presented
at the
Geosynthetics '87 Conference
New Orleans, Louisiana
February 24-26, 1987
H-I
-------
INTRODUCTION
The use of polymeric products in civil-engineering .applications has increased
dramatically over the past decade, particularly in the design and construction of
waste management facilities. These products include various rubber and plastic
membranes that have very low permeability, woven and nonwoven textiles that have
various degrees of permeability, special open constructions designed for high
permeability and liquid flow, and plastic pipes (_1). Except for plastic pipe,
these products are called geosynthetics.
Of particular importance is the wide range of functions that polymeric products
perform in double-liner systems for hazardous waste disposal facilities. These
products are based on a wide range of polymers including rubbers (elastomers),
plastics, fibers, and resins. With this great diversity in materials and products,
an array of laboratory tests are being performed on the materials and the products
to assess their quality and ability to perform in a specific application. Even for
hazardous waste containment applications when a single type of material is the
material fof choice, thorough testing and Devaluation of candidate materials are
necessary due to the differences in polymers and additives used in both geosyn-
thetics and plastic pipe.
This paper reviews some of the basic characteristics of the polymeric materials and
products that are used in the construction of double-liner systems and indicates
the effects of these characteristics on field performance and laboratory testing of
these products. Emphasis is placed on the testing of polymeric geomembranes and
compatibility testing.
POLYMERIC PRODUCTS IN A DOUBLE-LINER SYSTEM
Each construction material in a double-liner system requires testing and evaluation
in terms of the specific facility and condition in which it 1s designed to,perform.
Thus, if a material will probably be exposed to a waste liquid or Its vapors, it
must be compatible with that particular waste stream and be able to maintain its
properties over extended periods of time. Similarly, 1f the material is to be
subjected to loads and to elevated temperatures, it must be able to function as
required without failure.
H-2
-------
The following polymeric materials of construction are being used or being 2
suggested for use in double-liner systems (2):
Geomembranes—To provide a barrier between hazardous substances and mobile
polluting substances and the groundwater; in the closing of landfills to
provide a low-permeability cover barrier to prevent intrusion of rain
water.
Geotextiles—To provide separation between solid wastes and drainage
material and the leachate collection. system or between the membrane and
cover or embankment soils; to reinforce the membrane against puncture
from the subgrade; to provide drainage, such as in leachate collection
and leak-detection systems; to provide filtration around drainage pipes.
Drainage Nets—To provide drainage above and between liners; to provide
reinforcement for side slopes and embankments.
Plastic Pipe—To provide drainage in leachate collection and leak-detec-
tion systems. -Pip« is also used in the construction of monitoring ports,
manholes, and system cleanouts.
Figure 1 presents a schematic of a double-liner system with indications of poten-
tial failure modes for the polymeric components used in the subsystems.
BASIC CHARACTERISTICS OF POLYMERIC MATERIALS
All of the geosynthetic materials, as well as plastic pipe, discussed in this paper
are based on polymers, which are products of the chemical, plastics, rubber, and
fiber industries. From the viewpoint of composition, an almost infinite range of
polymeric materials can be produced. The polymeric materials used in the manufac-
ture of geosynthetics and pipe are given in Table 1. Polymers within a type can
vary according to grade and manufacturing process. In addition, considerable
variation among compositions based on the same polymer is introduced by the product
-manufacturer through -compounding with .ingredients..designed to enhance or develop
specific characteristics. Knowledge of the composition of each geosynthetic and
pipe can be important when dealing with waste liquids containing orgamcs.
Four general types of polymeric materials are used in geosynthetics:
- Thermoplastics and resins, such as PVC and EVA.
- Crosslinked elastomers, such as neoprene and EPDM.
- Semi crystalline plastics, such as polyethylenes.
- Highly crystalline, oriented polymers, such as polypropylene and
polyester fibers.
As all of these materials are polymeric, they have characteristics in common and
require a broad array of tests to characterize them (3). In designing containment
facilities and designing the tests needed to assess important design properties,
recognition must be given to basic characteristics of polymers. Some of the
implant characteristics of the polymers used in products for the construction of
double-liner systems are briefly discussed.
H-3
-------
Protective
Soil or Cover
(optional)
Fitter Mediura
(eg oeotextila)
Top Uner
(polymeric
geomcmbrm*)
Bottom -Compoira
Primary Lt*cKrcr
Collection and
Removal Syiwm
Secondary Leachau
Collection and
Removal Syram
Upper Component
(polymeric oeomembrjr*)
Lonrer Component
(compacad nil)
(not to salt)
Figure 1. Schematic of a polymeric geomembrane/composite double-liner system for
a landfill (2) and potential failure modes of the different components.
Potential failure modes of geomembranes:
1. Puncture due to settlement of components in leacnate collection
system or from irregularities in the subgrade.
2. Environmental stress-cracking of liner at bends and creases.
3. Bridging caused by localized subsidence in the subgrade.
4. Sloughing of protective soil cover due to low coefficient of
friction between membrane and soils.
5. Tensile stress under load.
6. Thermal cycling.
7. Loss of properties due to waste incompatibility.
Potential failure modes of geotextiles:
8. Loss of properties due to waste incompatibility leading to
reduced fluid flow.
9. Clogging or blinding of filter material by particles in the waste.
10. Tensile stress under load.
Potential failure modes of drainage nets:
11. Intrusion of membrane into the net, leading to clogging.
12. Loss of properties, leading to reduced fluid flow.
13. Collapse of the materials under waste load.
Potential failure modes of plastic pipe:
14. Collapse of pipe under load, particularly if incompatible with
wastes.
H-4
-------
TABLE 1. POLYMERS USED IN THE MANUFACTURE OF MAJOR PRODUCTS FOR
THE CONSTRUCTION OF WASTE MANAGEMENT FACILITIES
Polymer
Acrylonitri le butadiene styrene
Chlorinated polyethylene
Chlorosulfonated polyethylene
Ethylene propylene rubber
Ethylene vinyl acetate
Neoprene (chloroprene rubber)
Polyamide (nylon)
Polybutylene
Polyester
Polyester elastomer
Polyethylene:
Linear low-density
High-density
Polypropylene
Polyurethane
Polyvinyl chloride
Plasticized
Unplasticized
Type
Resin
Rubber
Rubber
Rubber
Resin
Rubber
Fiber /res in
Resin
Fiber/resin
Resin/rubber
Resin
Resin
Resin
Resin/rubber
Resin
Resin
Product
Geogrids
Geomem- Geo- and drain-
branes textiles age nets Pipes
••• ... ... X
x
... ... ...
X
«•• ... ...
x
... ... ...
x
... ... ...
x
... ... ...
*a x
* ... ... x
*a x x
x
" ••• ••• •••
Y
" • • • ••• •••
X ... XX
• •• A A •••
x
" ••• •*• •••
x
" ••• ••• •••
••• ••* ••• A
aUsed as reinforcing fabric in geomembranes.
Polymers Vary in Modulus and in Elongation at Break
Polymeric materials range from soft foam-like materials to high modulus structural
materials. Polymeric materials that are used in waste management facilities are
intermediate in modulus or stiffness. However, their elongation at break ranges
from 15% to as much as 1000%. Both properties are ..important considerations in
designing geosynthetics and plastic pipe.
Polymers are Sensitive to Organic Liquids and Vapors
As the polymeric compositions used in double-liner systems are organic in nature,
they are sensitive to organic liquids; they can absorb organics from waste liquids
and vapors and swell or can be leached and shrink. In either case, several prop-
erties of the composition can simultaneously change and their performance charac-
teristics can be altered. This sensitivity to organics shows the need for compati-
bility testing.
Polymers are Viscoelastlc and Sensitive to Temperature and Rate of Deformation
All polymeric materials are viscoelastic, that 1s, when undergoing a deformation
in varying degrees, both viscous and elastic behavior. The elastic
they show,
component behaves like a spring and is independent of rate of deformation. The
viscous component behaves like a dashpot and 1s highly dependent upon the rate
of deformation and upon temperature. Rubbers, such as natural rubber and some
H-5
-------
polyurethanes, tend to have highly elastic components, whereas many of the 5
plastics have highly viscous components. In performing tests in extension
or compression, the temperature and rate of deformation become important.
Most of the polymers used in geosynthetics and pipe vary greatly in properties with
temperature, even within the temperature range in which waste containment facil-
ities operate. At low temperatures some become glassy and brittle, and at high
temperatures the thermoplastic polymers become soft and plastic. These character-
istics will greatly affect the applications in which a polymeric material can be
used.
Due to the viscous component of polymeric compositions, the speed at which they are
deformed greatly affects the magnitude of the values that are obtained, e.g., ten-
sile or tear values. At high test speeds, modulus values generally are consider-
ably higher; the effect on-tensile strength and elongation at break values varies
with the polymer. In the case of semicrystalline materials, such as HOPE, high-
speed testing will not allow time for crystals to align themselves during the test,
thus resulting in lower tensile at break values than those obtained at lower
speeds. In service environments deformation rates can range from rapid impacts to
slow creep.
Polymers Tend to Creep and Relax in Stress
Polymeric materials have a relatively high tendency to creep, that is, to increase
in length or change dimensions under load or to relax in stress when placed in
constant strain. This characteristic is important to long-term exposure such as
would be encountered in a double-liner system. For example, in-place drainage nets
and pipes are under constant load and a geomembrane placed over a protrusion is
under constant stress. The absorption of organics can aggravate this tendency.
High Coefficient of Thermal Expansion
All polymeric materials have thermal coefficients approximately 10 times greater
than those of metals and concrete. For soft geomembranes, this is not a major
problem; however, for stiff membranes, such as the polyethylenes, changes in
temperature can cause considerable deformation and flexing of a liner when exposed
to normal weather and high stress in the liner when exposed to cold weather.
Importance of Thermal and Strain History
Polymeric materials tend to have "memory," that is, the deformation during process-
ing and forming into sheets leaves residual strain 1n many polymers, which is why
tensile and tear testing should be performed in both machine and transverse direc-
tions. Residual strain can cause shrinkage in the machine direction and expansion
in the transverse direction when the sheeting is warmed.
Elongation Under Biaxial Straining
Most of the tensile and tear testing for specification purposes is performed uni-
axially, which can yield high elongations. Performing the tests biaxially, that
is, deforming the materials simultaneously in machine and transverse directions,
yields considerably lower elongation values. This can show up 1n the testing of
puncture and hydrostatic resistances and in actual service.
H-6
-------
Broad Range of Permeability 6
The permeability of the polymeric compositions to various gases and vapors can vary
over several orders of magnitude. Generally, the presence of plasticizers in-
creases permeability and the presence of crystalline structure reduces permea-
bility. Also of importance is the relationship between the solubility character-
istics of the permeant and the polymer; the more soluble the permeant is in the
geomembrane, the higher the probability of permeation.
Stress-Cracking and Static Fatigue
Polymeric materials, as with other types of materials, are subject to fracture
after being under stress and strain for extended periods of time. A material under
constant stress loses tensile strength and elongation at break. Semicrystal1ine
polymeric compositions, when placed under stress in environments that affect the
surface of the material, can crack or craze. This phenomenon occurs with some
grades of polyethylene and polyester elastomers. The stress-cracking resistance of
semicrystalline polymers that might be used in contact with waste liquids over long
periods of time should be.assessed.
Amorphous and Crystalline Phases in Semicrystalline Polymers
Semicrystalline polymers, such as polyethylene, contain two basic phases: 1) an
amorphous phase in which the molecular structure is random, such as in a rubber;
and 2) a crystalline phase in which the molecular structure is highly ordered. The
crystalline phase imparts stiffness to the polymer and resists the absorption of
organic species, and the amorphous phase can absorb and transmit organics. Deform-
ation of a semicrystalline polymer results over time in molecular rearrangement in
the crystalline phase. Excessive deformation results in yielding and orientation
of the crystalline phase and subsequent loss in strength in the direction perpen-
dicular to the deformation.
Highly Resistant to Degradation
With proper- protection :through the use of stabilizers and antidegradants, poly-
mers used in the manufacture of geosynthetics and pipe can be highly resistant to
degradation, that is, with no adverse changes in molecular structure. Polymeric
compositions are still subject to loss in properties due to swelling, but polymer
molecular structure remains essentially undamaged.
Polymers in polymeric compositions are also highly resistant to biodegradation;
however, some compounding ingredients, such as plasticizers, may be biodegradable.
Biodegradation in such cases may result in adverse changes in the properties.
Combinations of Properties in Polymeric Compositions
A given polymer will tend to have a distinct pattern of properties which can be
modified somewhat by compounding. Assessing materials based upon a single pro-
perty, such as tensile strength, can lead to an incorrect selection of materials
because of inadequate values for other important properties, such as chemical
compatibility. For this reason, a group of tests are usually performed on a
material and the resulting test values are assessed as a group before a selection
should be made.
H-7
-------
PURPOSE AND TYPES OF LABORATORY TESTS
A double-lined waste management facility 1s a complex system, each component of
which must meet performance criteria for the service life of the facility. Failure
of a single component could lead to failure of the system. Due to the inaccessi-
bility of components of double-liner systems, rational selection and evaluation of
each component is of critical importance to the long-term functioning of the
facility. Rigorous testing programs designed to assess the properties of these
materials are an indispensable part of the design process.
Laboratory tests are performed for the following reasons:
- To assess the ability of certain materials to perform in specific field
envi ronments.
- To aid in the selection of materials for the construction of a specific
facility.
- To assess durability under some extreme conditions.
-To develop data useful in the designing of containment facilities.
- To ascertain for quality assurance purposes that the materials of con-
struction placed in the field meet design specifications.
- To identify the materials and follow changes in composition during
service.
- To monitor the properties of the liner during service.
Laboratory tests designed to -assess the ability of these polymeric construction
materials to perform as required in the design and to meet the challenges of the
field environment are needed.
The types -of tests-used .±0 assess the attributes of polymeric construction mate-
rials fall into several categories. Tests of mechanical properties are most
commonly used to assess the characteristics of these materials. The test values
are then used in the material specifications that are incorporated into the de-
sign documents. "At the present state of liner technology, the relationships
between mechanical properties of particular geosynthetics as measured in the
laboratory and their field performance have not been well defined. Thus, when only
laboratory test data on mechanical properties are available, the designer will
often rely upon his experience in the field as the basis for design judgment.
Performance tests are designed to assess the ability of one or more materials
to perform under a specific set of conditions that simulate those that exist in the
field. Performance tests are generally complex, usually involve many steps, and
need considerable control. Such tests are beginning to evolve for geosynthetics
and plastic pipe in double-liner systems. EPA Test Method 9090 for liner compati-
bility with a waste liquid is a performance type of test because an actual waste
liquid is used as the immersion medium (£).
*
A major difficulty in designing performance tests of the various materials under
conditions encountered in double-liner systems is the necessity of reproducing in
H-8
-------
the tests the field conditions in which the liner system will perform. For 8
example, they might need to include identical soils, at the correct"mois-
ture contents, wastes, and construction materials that will be used. Tests that
have been used and which relate to some aspects of field peformance include:
- Permeability of geomembranes, e.g., pouch test (_5).
- Fractional properties at the soil, membrane, and geotextile interface.
- Strength and elongation of geomembranes tested biaxially, e.g.,
hydrostatic resistance.
- Transmissivity, permittivity, and filter properties of geotextile,
soil, and geogrid systems.
Most performance tests of geosynthetics and plastic pipe in waste containment
applications as they exist today are in the early stages of development and
require additional research in order to understand and control the test variables
and to interpret, .the .test results. At present, field verification data and long
histories of use of these construction materials in waste liquid environments are
meager.
Analytical tests are used to determine the composition of materials and to evaluate
changes in composition over time under waste and environmental exposures (_6). They
include analyses for volatiles, ash content, analysis of the ash for trace" metals,
extractables (amount and composition), gas chromatography of extractables and by
pyroprobe, differential scanning calorimetry of semicrystalline compositions,
thermogravimetric analysis, and specific gravity. These tests can be used to
"fingerprint" a polymeric material for quality control purposes.
The testing of the various polymeric components used or potentially used in double-
liner systems are discussed in the following sections.
TESTING OF GEOMEMBRANES
The basic requirements of a geomembrane liner are low permeability to waste con-
stituents, compatibility with the waste liquid to be contained, durability for the
lifetime of the facility, and ease of construction and installation. Labora-
tory tests of these materials need to be selected or designed to assess these
attributes. It is also desirable to be able to identify each geomembrane in order
to be certain that an approved membrane is used in the final construction and to
follow the effect of an exposure on a geomembrane through testing samples of the
exposed liner. Table 2 presents a list of test methods that are being used in
assessing the various types of polymeric geomembranes. The testing of geomembranes
for use 1n the lining of waste disposal facilities has been discussed by Haxo
(7) and 1n the an EPA Technical Resource Document (8). Specific test methods,
including the modification of some ASTM methods, have been adopted by the National
Sanitation Foundation (9).
Permeability
As the primary function of a liner is to prevent the flow of mobile liquids and
other chemical species, permeability of the geomembrane to these species must
H-9
-------
TABLE Z. ATOOmATE 08 APfUCWLE TtST METHODS FOB UKEXPOSED POLPOIC CCONCMBXAICS
Property
Analytical properties
Volatile*
Ertractables
Ash
Specific gravity
Thermal analysis:
Differential sinning
calorl«etry (DSC)
Ther«ogravlBetry (T6A)
Physical properties
Thlctrvess - total
Costing OT«r fabric
Tensile properties
Tear resistance
Modulus of elasticity
Hardness
Puncture resistance
Hydrostatic resistance
Sea> strength:
In shear
In pee)
Ply adhesion
Environmental and
aglnq effects
Ozont cracilng
Environmental *tre*s-
cracklng
Low tenperature testing
Tensile properties at
elevated temperature
Dimensional stability
Air-oven aging
Hater vapor trans-
mission
Hater absorption
lawn Ion 1i standard
liquids
(•version In waste
liquid*
Soil burial
Outdoor ezpmarc
Tuk test
he-bran*
Thermoplastic
MTM-1*
MTN-2*
AS™ 0297.
Section 34
ASTM D792. Htd A
na
yes
AST* 0638
na
AST>1 0882.
ASTM 0638
ASTM 01004
(•od)
na
•ASTM 02240
Duro A or D
FTMS 101B.
Mtd 206S
na
ASTM 0882.
Mtd A (•od)
ASTM 04 13. Mach
Mtd Type 1 (BOd)
M
ASTM 0114g
na
ASTM 01790
ASTM 0638 (wad)
ASTN 01204
ASTM DS73 («od)
ASTM £96. Mtd BU
ASTM OS70
ASTM 0471, DS43
EPA 9090
ASTM D30S3
ASTM 04344
b
Liner Without Fabric
Cross linked
MTM-1^
MTM-2*
ASTM 0297,
Section 34
ASTM 0297,
Section IS
na
yes
ASTM 0412
na
ASTM 0412
ASTM D624. Die C
na
ASTM 02240
Duro A or D
FTMS 101B.
Mtd 206S
na
ASTM 0882.
Mtd A (mod)
ASTH 0413. Mach
Mtd Type 1 (Bod)
na
ASTM D1149
na
ASTM 0746
ASTM 0412 (ml)
ASTN D1204
ASTM 0573 (mi)
ASTM E96, Rtd BU
ASTH 0471
ASTM 0471
EPA 9090
ASTM 03O83
ASTM 04364
b
lelnf ore event'
Setrlcrj-italllne
MTM-1*
MTM-2*
ASTM 0297.
Section 34
ASTM 0792, Mtd A
yes
yes
ASTM D638
na
ASTM 0638 (xxl)
ASTM 01004
ASTM OR82. Mtd A
ASTM 02240
Duro A or 0
FTMS 1018.
Rtd 206S
ASTM 0751. Mtd A
ASTM 0882.
Mtd A («Dd)
ASTM 0413. Mich
Mtd Type 1 («od)
na
na
ASTM D1693
ASTM 01790
ASTM D746
ASTM 0638 (iod)
ASTM 01204
ASTN OS71 (mo4)
ASTM £96. Kid BU
ASTH DS70
ASTH 0543
EPA 9090
ASTM 03003
ASTH 04364
ta
Fabric reinforced
MTM.1I
(on seltraoe and
reinforced sheeting)
MTM-J*
(on selvage and rein-
forced sheeting)
ASTM 0297.
Section 34
(on selvage)
ASTM 0732, Hid A
(on selvage)
na
yes
ASTM 07S1. Section £
Optical Method
ASTM 07S1, Mtd A and B
(ASTM DOB on itlvage)
ASTM 0751, Tongue Mtd
(•Ddtfleri)
na
ASTM 02240
Dum A or D
(selvage only)
FTMS 101B.
Mtd 2U31 and 2065
ASTH 0751, Mtd A
ASTM 0751.
Mtd A (mot)
ASTM 04 13, Mach
Mtd Type 1 («od)
ASTM 0413. Mach
Mtd Type 1
ASTM 0751. Sections 39-42
ASTM 01149
na
ASTM 02136
ASTM 0731 Mtd B (ind)
ASTM DI204
ASTM DS73 (•*)
ASTM 196, Mtd BU
ASTM DS70
ASTN 0471. DM3
EPA 9090
ASTM 03083
ASTM D4JM
»
•See reference (8).
*S«« reference (TZl.
na • lot applicable.
H-10
-------
be assessed. Transport through a geomembrane occurs on a molecular 10
level and depends on the solubility of the permeating species and Us dif-
fus1b1lity in the membrane. ...A concentration or partial pressure gradient across
the membrane is the driving force for the direction and rate of transport. The
species migrates through the membrane from higher to lower concentration; at a
small difference in concentration, the transmission can approach zero for sp'ecific
species. In contrast, soils and clays are porous and the driving force for per-
meation is the hydraulic head. Test methods that are available and have been used
to assess the permeability of polymeric geomembranes include:
- ASTM D814, for determining organic vapor transmission.
- ASTM D1434, for determining gas transmission (10).
- ASTM E96, for determining moisture, vapor, and modified- for organic
vapor transmission (10).
- Pouch test, for determining transmission of organics in dilute solu-
tions (_5).
The permeability of geomembranes to different species can vary by orders of mag-
nitude, depending on the composition and solubility of the migrating species in the
geomembrane (10, 11).. The permeation of a given species is also affected by such
factors as crystallinity. filler content, density, crosslink density of the poly-
mer, thickness of the geomembrane, temperature, and the driving force across the
membrane. Also, swelling of a geomembrane during service can significantly in-
crease its permeability to some species.
Compatibility with Wastes
The selection of a geomembrane depends on whether it is .compatible with the
liquid to be contained (12). A liner is compatible with a liquid if, on long
exposure, its properties, e.g., permeability and mechanical properties, do not
change more than reasonable amounts depending on the type of membrane. In the
absence of criteria for determining the success or failure of materials under
exposure to specific wastes, experience is required in interpreting changes or
trends that develop over time.
EPA Test Method 9090 was designed to assess the compatibility of geomembranes and
waste liquids by simulating some of the conditions a geomembrane would encounter as
an unstretched coupon in representative samples of the waste liquids or leachates
to be contained (4J. In this test, liner samples 1n slab form are immersed for up
to four months at" 23 and 50°C in the waste liquid. Testing-is performed on the
unexposed membranes for baseline data and on samples exposed to the waste liquids
for 30, 60, 90, and 120 days to assess the effects of immersion. Testing required
by the method includes determination of tensile properties, tear resistance,
puncture resistance, and hardness. In addition, the weight and dimensions of the
individual test slabs before and after exposure are measured.
A major challenge in conducting the 9090 test is maintaining, as closely as pos-
sible, the composition of the waste liquid 1n the test cells for the duration
of the tests as it would be encountered in the "real world." Changes in the
concentration of dissolved constituents in a waste liquid can occur because of loss
H-ll
-------
11
of volatiles from the immersion cell or absorption by the geomembrane under
test. Consequently, if the leachate contains volatile organics, it is
necessary to seal the cells in which samples are immersed and to test the samples
promptly after removal. Also, though not required by the 9090 test method, it may
be necessary to change the liquid monthly at the time the sample 1s removed in
order to maintain a constant concentration of the organics. Table 3 illustrates
partitioning of organics between water and HOPE and the degree that organics are
absorbed by the HOPE sample immersed in an aqueous solution of 10 organics in a
9090-type test. The acetone and methyl ethyl ketone preferentially partitioned to
water, whereas the other 8 organics partitioned to the HOPE.
TABLE 3. PARTITIONING OF ORGANIC SOLVENTS BETWEEN WATER AND
AN HOPE MEMBRANE AFTER 30 DAYS OF EXPOSURE IN A 23°C AQUEOUS
SOLUTION SPIKED WITH TEN ORGANICS
Organic in spike
Acetone
Methyl ethyl ketone
Trichloroethane
Benzene
Trichloroethylene
Toluene
m-Xylene
o-Xylene
Tri butyl phosphate
Di (ethyl hexyl ) phthalate
Initial
spike3
(mg/g)
0.198
0.201
0.335
0.220
0.366
0.217
0.072
0.073
0.243
0.247
Concentration
in water at
30 daysb
(mg/g)
e
0.201
0.000
0.018
0.032
0.031
0.0089
0.0034
0.016
0.0057
Concentration
in HOPE membrane
at 30 daysc
(mg/g)
0.000
0.000
1.42
0.46
1.58
2.63
1.46
1.17
0.32
0.11
Ratiod
CPE/CW
• • •
<0.002
>1400
26
49
85
164
344
20
19
aBased upon the solubility of individual organic in water.
^Concentration determined by gas chromatography.
cConcentration determined by headspace gas chromatography.
dRatio of concentration of the organic in the HOPE membrane divided by the
concentration in water.
eNot detectable by the gas chromatograph.
Partial results of a 9090 test of an 80-mil HOPE geomembrane in a waste liquid
containing organics are presented in Table 4. The test was conducted in a manner
to prevent loss of volatiles and to maintain concentration of the organic con-
stituents in the waste liquid. Determination of the volatiles and extractables of
the exposed sample Improves the interpretation of the results. The current EPA
Test Method 9090 does not include testing of seams and the effect of strain on a
geomembrane (4_). Inclusion of such testing would enhance the method and make
conclusions regarding compatibility more reliable.
Durability
A polymeric geomembrane used to line a hazardous waste storage and disposal
facility must maintain Its integrity and performance characteristics over the
designed life of the facility. Liners must resist physical damage during in-
stallation and service; the integrity of the seams must be maintained so that
cracks, breaks, tears, and other holes do not develop in the liner system. Fabric
H-12
-------
reinforcement is used with CSPE, CPE, and other polymers to increase 12
durability, particularly during Installation. Ultimately, the service life
of a given liner will depend on the intrinsic durability of the material and on
the conditions under which 1t is exposed during service (13).
TABLE 4. PARTIAL RESULTS OF COMPATIBILITY TESTING OF AN
80-MIL HOPE GEOMEMBRANE ON IMMERSION IN A LEACHATE3 AT 23°C
Original Values of Properties and Percent Retention of Values after One,
Two, Three, and Four Months of Immersion at 23°C
Property
Analytical properties
Volatile*, %
Extractables, I
Dimensional properties
Weightc
Physical properties
Tensile at yield
Tensile at break
"
Elongation at break
Stress at 100%
elongation
Modulus of elasticity0"
Tear strength
Direction
of test
Initial
values
0.1
SO. 6
Exposure time, months
1
2.64
0.90
2
Test
2.89
1.43
3
values
3.26
1.40
4
3.13
b
Percent chanae
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
• • •
18.5 MPa
18.8 MPa
29.9 MPa
30.7 MPa
835i
83 OS
13.0 MPa
12.7 MPa
855 MPa
811 MPa
148 kN/m
148 kN/m
+5.5
90
90
89
91
98
100
90
91
73
75
89
86
+6.0
Percent
88
92
91
82
99
93
89
93
e
69
93
91
+6.0
retention
89
90
102
97
105
96
90
92
60
63
89
89
+5.9
89
91
93
83
98
93
90
91
62
61
88
88
Puncture resistance
Maximum stress, normalized
for 100-mil sheeting, N
Retention of stress for
Test values
717
725
669
657
672
100-mil sheeting, "%
Elongation at puncture, mm
Harrlnoc^ Hum D nnln^^
5-second reading
100
15.5
63
101
19.3
-8
93
18.0
Change
-8
92
17.0
in points
-9
94
18.3
-7
jM-eachate was changed monthly.
"Not measured.
cWeight gain may be due to swell and/or encrustation of sample.
Measured using 12.7 mm x 203-mm strip specimens with an initial jaw separation
of 10 mra and an initial strain rate of 0.1 mm/mm min. Using a specimen with a
250-mm gage length, recommended as standard in ASTM D882-83, would result in
somewhat higher values.
Unreliable result.
H-13
-------
Laboratory tests for assessing the durability of geomembranes under dif- 13
ferent environmental conditions range from chemical analyses to tests of
mechanical properties (e.g., tensile properties, tear resistance, puncture re-
sistance, and impact resistance) under various exposures in aggressive environ-
ments, such as exposure to high and low temperatures, to ozone while under strain,
to ultraviolet light, to stress and strain for extended periods of time, and to
the combined effects of chemicals and stress. Specific tests to assess these
properties are listed in Table 2 for different types of geomembranes.
Important in long-term service of a polymeric geomembrane liner is its ability to
resist the effects of creep and biaxial strain that will occur when it is under
load and rests on a nonplanar or irregular surface, such as exists at the bottom of
a containment facility. Cracks and breaks can occur in a polymeric geomembrane
at significantly lower stress values than are encountered in the simple uniaxial
tensile test.
As with compatibility testing, maximum changes in properties that can take place
without affecting overall performance have not been established. Nevertheless,
laboratory testing of several properties can yield data indicative of durability.
Seamability and Quality of Seams
In constructing a large continuous leakproof liner from prefabricated sheeting,
pieces of sheeting must be seamed. Sheetings of a roll width less than 1.8 m
are seamed together in a factory to form panels which are brought to the field and
seamed. Sheeting of a roll width greater than 6 m is brought to the field in
rolls which are then seamed. In either case, the geomembrane must be seamable and
yield reliable seams that are mechanically sound and can withstand exposure to
waste liquids for extended periods of time. Thermoplastic materials which can melt
or which can be dissolved in a solvent yield seams that can be monolithic and/or
homogeneous, i.e., the interface between the layers has been eliminated. This
contrasts to sheetings which are seamed with adhesives of a composition different
from the parent material. Seams are tested in both peel and shear modes in
accordance with methods given in Table 2. In addition, static tests can be run in
peel and 'shear by dead-weight loading. All of these tests can be performed at
elevated temperatures, after various aging periods, and after immersion in solvents
or in waste liquids as part of EPA Test Method 9090.
Various measurements and observations can be made to assess the quality of the
seams. In making an assessment, it is important not only to know the force re-
quired to break seams, but also to know the durability of the seam and the manner
in which a test specimen of the seam breaks. The quality of a seam can be assessed
by the following observations:
- Locus of break—a break in the parent material is desirable, such as a
"film tearing bond." Failure at the interface between bonded surfaces
is undesirable as 1t may be indicative of inadequate retention of
adhesion on long exposure.
- Time to break when tested under tensile load in the static mode.
- Effects of temperature and other exposures on the magnitude or locus
of break. »
H-14
-------
These observations can be used in setting specifications for seam quality. 14
Laboratory tests should be performed on samples of seams cut from liners
installed in the field as part of quality assurance.
Fingerprinting of Geomembranes
Because of the wide range of polymeric geomembranes that may be encountered,
analysis and fingerprinting can be useful. For example, the analysis and finger-
printing of a polymeric geomembrane liner that has been tested for compatibility
with, a given waste liquid in accordance with EPA Test Method 9090 can be used at
the time of liner installation for the following purposes:
- As a means of characterizing and identifying the specific sheeting.
- As a baseline for monitoring the effects of exposure on the liner.
- To determine which constituents of the waste liquid were absorbed
during the 9090 test and thus could affect the chemical compatibility
of the waste and liner in service.
Specific analyses that may be used for fingerprinting are suggested by Haxo (6).
Table 2 lists specific test methods for many of these .analyses. ~~
TESTING OF GEOTEXTILES
The tests for characterizing geotextiles that have not been exposed to wastes are
fully described by Koerner (14). Also, ASTH Committee D35 is developing specific
test methods which can characterize the properties associated with the respective
functions. Currently used test methods are:
Property Test method number
Thickness ASTH 01777*
Mass/unit area ASTH D3776-84
Percent open area CWO 22125-86
Permittivity ASTH 04491
Equivalent opening size CWO 02215
Puncture A5TH D3787 (modified)
Burst strength ASTM 03786
Grab tensile/elongation (wide-width strip) ASTH D1682b
Ultraviolet resistance ASTH D4355C
Transmissivity ASTM 035 Committee Draft,
Designation 03.84.02
a2 kPa loading.
^Section 16 (Grab test G) using 100 mm x 200-mn sample, 75-mm gauge length,
25-mm wide x 50-mm long grip, strain rate 305 mm/minute, using a constant
rate of extension tester.
C500 hours.
For assessing geotextiles for use in waste containment applications, exposure to
waste liquid for four months under EPA Test Method 9090 conditions is suggested.
The laboratory performance testing of geotextiles in waste liquids under load poses
a problem due to the size of the test specimens and the handling of large amounts
H-15
-------
of waste liquids. In our laboratory we have performed compatibility ^
testing of 75 mm x 150-mm geotextile specimens 1n accordance with ASTM D751
by the grab method. Wet specimens were tested throughout. The unexposed speci-
mens were first immersed in water and then tested. The exposed specimens were
"dewatnred with a roller and then wrapped in a thin polyethylene film and tested.
As the elongation properties of the film exceeded that of the fabric, it did not
break; thus, the waste liquid was contained.
Performance testing of geotextile/soi1 systems to determine filter characteristics
are reported (_15_, _16_). Martin et al, also performed tests on drainage material/
soil systems to study the effects of overburden pressures .on. transmissivity of
geotextiles (17). Raumann conducted similar tests on geogrids (_18). Performance
tests have also been conducted on geomembrane/geotextile/soil systems to evaluate
the fractional coefficient rt the material interfaces (_!£).
TESTING OF DRAINAGE NETS
This group of geosynthetics, which includes geogrids, geonets, and a variety of
open constructions, are based primarily on polyethylenes and polypropylenes. As
.such, some of their attributes are similar to those of polyethylene geomembranes.
Geonets that are used for drainage in double-liner systems must maintain their
drainage capability over extended periods of time. As these materials are poly-
meric, they are subject to creep and compression under loads, which will tend to
reduce their transmissivity. The polymeric geogrid probably will absorb organic
constituents from the waste liquid, which will cause it to soften and lose compres-
sive strength and result in greater creep and further loss of transmissivity. If
the lateral mechanical stability decreases, the three-dimensional structure of the
net could collapse and lose drainage capacity.
A test that would be indicative of the performance of the geogrid as a drainage
medium is to place the geogrid between two stiff liners or plates while in contact
with the waste liquid and under load, during which time the transmis-sivity is
measured. It would be expected that the geonet would compress and creep with time.
Reduction in transmissivity would be expected, but the magnitude would vary with
the material, temperature, load, and chemical absorption; however, no test of this
type has yet been developed.
A modified test procedure would involve testing samples of geonet for transmis-
sivity after they have been exposed to a waste liquid. A load that corresponds in
magnitude to service conditions would be applied and the transmissivity determined.
This procedure would require that the load be applied for a sufficient length of
time to allow for creep and compression of the tested sample. If water instead of
waste liquid is used to determine transmissivity, some of the organics in the
geogrid may leach out and cause changes in the properties of the geonet.
An alternate test procedure which we have followed to measure compatibility of
geonets with waste liquids is to immerse samples of geonets for up to four months
in a manner similar to that used for geomembranes, and measure such properties as
tensile and compression modulus as a function of exposure time. Weight changes,
volatiles, and extractables are also measured. Test results are treated similarly
to those obtained on geomembranes.
H-16
-------
TESTING OF PLASTIC PIPE 16
A wide variety of test methods for characterizing plastic pipe has been published
by ASTM, the Plastic Pipe Institute, the Gas Research Institute, and the National
Sanitation Foundation. Due to their good chemical resistance, plastic pipes have
found considerable use in the handling of chemicals. However, the resistance can
vary considerably from polymer to polymer. In waste containment facilities, PVC
and HOPE pipes are used predominately. Nevertheless, pipes have collapsed due to
organic solvent absorption and softening of the pipe.
Inasmuch as the leachate collection and leak-detection systems of double liner
systems must function for extended periods of time, it is desirable to assess the
compatibility of the pipe with the waste liquid. This can be done by exposing
sections of pipe in waste liquid under conditions similar to those used in the EPA
9090 test and testing the sections after exposure in accordance with a method
selected from ASTM D2412. The size of the pipe, e.g., 150 mm in diameter, and the
need for replication may require large tanks and a considerable amount of waste
liquid. The relatively large mass of the pipe could absorb considerable portions
of the organic constituents in the liquid, resulting in a reduction of their
concentrations and the need to replace the waste liquid.
In an alternate procedure which we have conducted, the pipe is tested for tensile
properties parallel to the length of the pipe and for compressive modulus of a ring
cut through the cross section. In this procedure, two types of specimens cut from
the pipe are exposed and tested: cross-sectional rings 25 mm in length and longi-
tudinal strips cut radially and machined to the proper thickness. The strips are
tested for weight change, extractables and volatiles, tensile strength, elongation,
and modulus of elasticity before and after immersion as in EPA Test Method 9090.
The rings are tested in compression before and after exposure to the waste liquid
to measure changes in modulus. Also measured are weight and hardness to determine
changes in these properties.
DISCUSSION
As yet, maximum changes in properties which correlate with serviceability limits
have not been established. Inasmuch as the effects of environmental exposures vary
with the polymer, each material would have a separate set of maxima. Expert sys-
tems are being evolved by the U.S. Environmental Protection Agency to aid in asses-
sing compatibility of liners and waste liquids (19). However, feedback from the
field performance of liners and from testing liners that have been in service is
needed to established correlation between field performance and laboratory testing.
ACKNOWLEDGMENTS
The major portion of the work reported in this paper was performed under Contract
68-03-2173, "Evaluation of Liner Materials Exposed to Hazardous and Toxic Wastes,"
Contract 68-03-2969, "Long-term Testing of Liner Materials," and Contract 68-03-
3213, "Use of Cohesive Energy Determinations for Predicting Membrane/Waste Chemical
Compatibility and Service Life Estimates," with the Hazardous Waste Engineering
Research Laboratory of the U.S. Environmental Protection Agency, Cincinnati, Ohio.
H-17
-------
REFERENCES 17
1. Giroud, J. P. 1984. Geotextiles and Geomembranes. Geotextiles and Geomem-
branes, Vol. 1, pp. 5-40.
2. EPA/OSW. 1985. Minimum Technology Guidance on Double Liner Systems for
Landfills and Surface Impoundments. EPA 530-SW-85-014, Hay 24, 1985. U.S.
Environmental Protection Agency. Washington, D.C.
3. Mark, H. F, N. G. Gaylord, and N. M. Bikales. 1965-76. Encyclopedia of
Polymer Science and Technology—Plastics, Resins, Rubbers, Fibers. Inter-
science, New York, NY.
4. EPA/OSW. 1984. Method 9090, Compatibility Test for Wastes and Membrane
Liners. Noticed in the Federal Register, October 1, 1984, Vol. 49, No. 191,
pp. 38792-93.
5. Haxo, H. E., and N. A. Nelson. 1984. Permeability Characteristics of
Flexible Membrane Liners Measured in Pouch Tests. In: Proceedings of the
Tenth Annual Research Symposium: Land Disposal of Hazardous Waste. EPA-
600/9-84-007. U.S. EPA, Cincinnati, Ohio. pp. 230-251.
6. Haxo, H. E. 1983. Analysis and Fingerprinting of Unexposed and Exposed
Polymeric Membrane Liners. In: Proceedings of the Ninth Annual Research
Symposium: Land Disposal, Incineration, and Treatment of Hazardous Waste.
EPA-600/9-83-018. U.S. EPA, Cincinnati, Ohio. pp. 157-171.
7. Haxo, H. E. 1981. Testing of Materials for Use in Lining Waste Disposal
Facilities. In: Hazardous Solid Waste Testing, First Conference, eds.,
R. A. Conway and B. C. Malloy. 'ASTM Special Technical Publication 760.-
ASTM, Philadelphia, Pennsylvania, pp. 269-292.
8. Matrecon, Inc. 1983. Lining of Waste Impoundment and Disposal Facilities.
SW-870 Revised. U.S. EPA, Washington, D.C. 448 pp. GPO #055-00000231-2.
9. National Sanitation Foundation. 1983. Standard Number 54, Flexible Membrane
Liners. National Sanitation Foundation, Ann Arbor, MI.
10. Haxo, H. E., J. A. Miedema, and N. A. Nelson. 1984. Permeability of Poly-
meric Lining Materials for Waste Management Facilities. In: Migration of
Gases, Liquids, and Solids in Elastomers. Education Symposium. Fall Meeting
- Denver, Colorado. Rubber Division, American Chemical Society. The John H.
Gifford Memorial Library A Information Center, The University of Akron, Akron,
Ohio.
11. August, H., and R. Tatzky. 1984. Permeabilities of Commercially Available
Polymeric Liners for Hazardous Landfill Leachate Organic Constituents. In:
Proceeding of the International Conference on Geomembranes, June 20-24,
1984, Denver, Colorado. Industrial Fabrics Association International, St.
Paul, MN. pp. 163-168.
H-18
-------
12.
13.
14.
15
16.
17
Haxo, H. E., R. S.
Dakesslan. 1985.
and Toxic Wastes.
Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S. 13
Final Report: Liner Materials Exposed to Hazardous
EPA-600/2-84-169. U.S. EPA, Cincinnati, Ohio. 256 pp.
Haxo, H. E., and N. A. Nelson. 1984. Factors in the Durability of Polymeric
Membrane Liners. In: Proceedings of the International Conference on Geomem-
branes, Denver, Colorado. Volume II. Industrial Fabrics Association In-
ternational, St. Paul, Minnesota, pp. 287-292.
.Koerner, R. M.
wood Cliffs, NJ.
1986. Designing with
424 pp.
Geosynthetics. Prentice-Hall, Engle-
Koerner, R. M, and F. K. Ko. 1982. Laboratory Studies on Long-Term Drainage
Capability of Geotextiles. In: Proceedings of the Second International
Conference on Geotextiles, Las Vegas, NV. Volume I. Industrial Fabrics
Association International, St. Paul, Minnesota, pp. 91-96.
Koerner, R. M., and J. E. Sankey. 1982. Transmissivity of Geotextiles and
Geotextile/Soil Systems. In: Proceedings of the Second International Con-
ference on Geotextiles, Las Vegas, NV. Volume I. Industrial Fabrics As-
sociation International, St. Paul, Minnesota, pp. 173-76.
Martin, J. P., Koerner, R. M., and J. E Whitty. 1984. Experimental Friction
Evaluation of Slippage Between Geomembranes, Geotextiles, and Soils. In:
Proceedings of the International Conference on Geomembranes, Denver, CO.
Volume I. Industrial Fabrics Association International, St. Paul, Minnesota.
pp. 191-196.
In-plane Permeability of Compressed
18. Raumann, G. 1982.
Proceedings of the Second International Conference on Geotextiles,
NV. Volume I. Industrial Fabrics Association International,
Minnesota, pp. 55-60.
Geotextiles. In:
Las Vegas,
St. Paul,
19. Rossman, Lewis A., and H. E. Haxo. 1985. A Rule-Based Inference system for
Liner/Waste Compatibility. In: Proceedings of the 1985 Speciality Conference
of the American Society of Civil Engineers. ASCE, New York. pp. 583-590.
H-19
-------
APPENDIX I
-------
METHOD 9090
COMPATIBILITY TEST FOR WASTES AND HEHBRANF
1.0 SCOPE AND APPLICATION
1.1 Method 9090 Is Intended for use 1n determining the effects
chemicals 1n a surface Impoundment, waste pile, or landfill on the physici
properties of flexible membrane Uner (FWL) materials Intended to cental
them. Data from these tests will assist 1n deciding whether a given liner
material 1s acceptable for the Intended application.
2.0 SUMMARY OF METHOD
2.1 In order to estimate waste/liner compatibility, the Hner material
1s Immersed 1n the chemical environment for minimum periods of 120 days at
room temperature (23 + 2*C) and at 50 + 2*C. In cases where the FML will be
used 1n a chemical environment at elevated ten^eratures, the 1nners1on.testing
shall be run at the elevated temperatures 1f they are expected to be higher
than 50*C. Whenever possible, the use of longer exposure times 1s
recommended. Cooparison of measurements of the membrane's physical
properties, taken periodically before and after contact with the waste fluid,
1s used to estimate the compatibility of the Hner with the waste over time.
3.0 INTERFERENCES (Not Applicable)
4.0 APPARATUS AND MATERIALS
NOTE: In general, the following definitions will be.used 1n this method:
1. Sample — * representative piece of the Hner material proposed for
use that 1s of sufficient size to allow for the removal of
all necessary specimens.
2. Specimen — a piece of material, cut from a sample, appropriately
shaped and prepared so that It 1s ready to use for a test.
4.1 Exposure tank: Of a size sufficient to contain the samples, with
provisions for supporting the samples so that they do not touch the bottom or
sides of the tank or each other, and for stirring the liquid 1n the tank. The
tank should be coapatlble with the waste fluid and Impermeable to any of the
constituents they art Intended to contain. The tank shall be equipped with a
means for maintaining the solution at room temperature (23 + 2' C) and 50 +
2*C and for preventing evaporation of the solution (e.g., use a cover equipped
with a reflux condenser, or seal the tank with a Teflon gasket and use an
airtight cover). Both sides of the Hner material shall be exposed to the
chemical environment. The pressure Inside the tank must be the same as that
outside the tank. If the Hner has a side that (1) is not exposed to the
9090 - 1
Revision 0
Date September 1986
1-1
-------
waste 1n actual use and (2) 1s not designed to withstand exposure to the
chemical environment, then such a Uner may be treated with only the barrier
surface exposed.
4.2 Stress-strain machine suitable for measuring elongation, tensile
strength, tear resistance, puncture resistance, modulus of elasticity, and ply
adhesion.
4.3 Jlji for testing puncture resistance for use with FTMS 101C, Method
2065.
4.4 Liner sample labels and holders made of materials known to be
resistant to the specific wastes.
4.5 Oven at 105 + 2*C.
4.6 Dial alcrometer.
4.7 Analytical balance.
4.8 Apparatus for determining extractable content of Uner materials.
NOTE: A minimum quantity of representative waste fluid necessary to
conduct this test has not been specified 1n this method because
the amount will vary depending upon the waste compostlon and the
type of Uner material. For example, certain organic waste
constituents, 1f present 1n the representative waste fluid, can be
absorbed by the Uner material, thereby changing the concentration
of the chemicals 1n the waste. This change In waste coaposltlon
may require the waste fluid to be replaced at least monthly In
order to maintain representative conditions 1n the waste fluid.
The amount of waste fluid necessary to maintain representative
waste conditions will depend on factors such as the volume of
constituents absorbed by the specific Uner material and the
concentration of the chemical constituents 1n the waste.
5.0 REAGENTS (Not Applicable)
6.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING
6.1 For Information on what constitutes a representative sample of the
waste fluid, refer to the following guidance document:
Permit Applicants' Guidance Manual for Hazardous Waste Land Treatment,
Storage, and Disposal Facilities; Final Draft; Chap. 5, pp. 15-17;
Chap. 6, pp. 18-21; and Chap. 8, pp. 13-16, May 1984.
9090 - 2
1-2
Revision 0
Date Scptencer 1986
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7.0 PROCEDURE
7.1 Obtain a representative sample of the waste fluid. If a waste
sample 1s received 1n more than one container, blend thoroughly. Mote any
signs of stratification. If stratification exists, Uner samples Bust be
placed 1n each of the phases. In cases where the waste fluid Is expected to
stratify and the phases cannot be separated, the number of 1»*ened samples
per exposure period can be Increased (e.g., 1f the waste fluid has two phases,
then 2 samples per exposure period are needed) so that test samples exposed at
each level of the waste can b« tested. If the waste to be contained 1n the
land disposal unit 1s 1n solid form, generate a synthetic leachate (See Step
7.9.1).
7.2 Perform the following tests on unexoosed samples of the polymeric
membrane Uner material at 23 + 2*C and 50 + 2'C (see Steps 7.9.2 and 7.9.3
below for additional tests suggested for specific circumstances). Tests for
tear resistance and tensile properties are to be performed according to the
protocols referenced 1n Table 1. See Figure 1 for cutting patterns for
nonreinforced liners, Figure 2 for cutting patterns for reinforced liners, and
Figure 3 for cutting patterns for semi crystal line liners. (Table 2,.at the end
of this method, gives characteristics of various polyweric liner materials.)
1. Tear resistance, machine and transverse directions, three specimens
each direction for nonreinforced Uner materials only. See Table 1
for appropriate test method, the recommended test speed, and the
values to be reported.
2. Puncture resistance, two specimens, FTMS 101C, Method 2065. See
Figure 1, 2, or 3, as applicable, for sample cutting patterns.
3. Tensile properties, machine and transverse directions, three tensile
specimens 1n each direction. See Table 1 for appropriate test
method, the recomended test speed, and the values to b« reported.
See Figure 4 for tensile dumbbell cutting pattern dimensions for
nonrelnforced Uner samples.
4. Hardness, three specimens, Duro A (Duro D 1f Ouro A reading 1s
greater than 80), ASTM D2240. The hardness specimen thickness for
Duro A 1s 1/4 In., and for Duro D 1t 1s 1/8 1n. The specimen
dimensions are 1 1n. by 1 1n.
5. Elongation at break. This test 1s to be performed only on membrane
materials that do not have a fabric or other nonelastooeric support
as part of the liner.
6. Modulus of elasticity, machine and transverse directions, two
specimens each direction for semi crystalline liner materials only,
ASTM D8S2 modified Method A (see Table 1).
7. Volatile* content, SV 870, Appendix III-O.
8. Extractables content, SV 870, Appendix III-E.
9090 - 3
Revision 0
Date September 1986
1-3
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Table 1. Physical testing of eMposed Mbrants In liner-wast* llcfjld onpatlblllty Uit
> n
r* <
n -••
i/i o
n a
o
T>pe of uapuund and
comtrucllon
Cross!Inked or vulcanized
Thermoplastic
Sealcrystatllne
Fabr Ic-relnforced*
Tensile properties Method
Type of 9>ectawn
ASTM0412
tU*bellb
ASTH 0618 ASTM 0638
Dt*fabe1lb D.«ttMllb
ASTM 0751. Method B
l-ln. wtda strip and 2-1n. Jjw
Hater of specimens
Speed of test
Values to be reported
Of elasticity MtlKMl
of jp*c1»em
!peed oT test
Values reported
Tear resistance Mttod
Type or
Hurtwr of speclwns
Speed of test
Values reported
reslstinte •elhod
T)pe or
H(4>er or
Spred or test
Vjilues reported
3 In «»di direction
n IP-
Tensile strength, psl
Elorastlon »t break, t
Tensile set «rter break. 1
Stress at 100 and 200K
elongation, psl
ASTMDW4
PleC
] In each direction
20 IP*
Stress, ppl
FTHS IOIC. Method 2065
2 In. scfiare
2
20 lp«
Cage, all
Stress. lb
Elongation. In.
3 In each direction
20 (pa
Tensile strength, psl
Elongation at break, 1
Tensile set afler break, f
Stress at 100 and 2001
elongation, psl
ASTHIOM
3 In each direction
20 Ipi
Stress, ppl
FTH5 IOIC. Method 2065
2 In. square
20 lp«
Cage. •!!
Stress. lb
riorqatlon. In.
3 In each direction
2 Ip*
Tensile strength at yield, psl
Elongation at yield. 1
Tensile stt at break, psl
Elongation at break, psl
Tensile set afler break, t
Stress at 100 and 2001
elongation, psl
AS1M 0082, Method A
Strip: 0.5 In. Mid* and 6. In long
at a 2 In. Jax separation
2 In each direction
0.2 IP*
Greatest slope of Initial stress -
strain curve, psl
ASTHDI004
2 In each direction
2 1p*
Haxliui stress, ppl
FTHS IOIC. Method 2055
2 In.
20 1p*
Cage. •!!
Stress lb
Elanr>itlon, In.
separation
3 In each direction
12 IP*
Tensile at fabric break, ppl
Elomatlon at fabric break. 1
Tensile at ultlMte brmk. ppl
Elongation at ultlnle break, ppl
Tensile set after brink. 1
Stress at ion nnd TOnt
elongation, psl
FTHS IOIC. Method 20T.5
2 In. sojMre
2
20 Ip*
Gage. •«!
Stress, lb
Elongation. In.
*Can be themplasttc. crossl Inked, or vulcanized motoranc.
Figure 4.
performed on this aaterlal.
tear resistance test Is ruajeatufcd for fabric-reinforced sheetings In the
as ASIH 0674. Die C.
slon study.
-------
Ij^^f^^^^^
Puncture test specimens
Teir test speciucns
Yol«t11es test spectet
Tensile test specimens
fct 10
Figure 1 . Suggested ptttem for cutting test sp«c1t«ns froa
nonr«1nforce
-------
Yolatn« t«st sptdccn
Puncturt test sptcinens
i^SV.-^^f^&?^~^.-
1^S^^^^'>^^^^^^
^•C^-.**- ^U^-^^-^^^T^fc *^ A-fc^ "-^Tt^m.'T^^%.^^L^ -'^-J*"^^"^^
j^]^^ Ply adhesion test specimens^
^^ri^TtSi^r^^l-.^v/Ir^^-^^""
test specimens.^" "V'-^J
•''
Hot CO »dle
Figure 2 . Suggested pattern for cutting test
fabric rtlnforced Innened Hner i«nples. Mote: To
tvold t
-------
Modulus of tUstldty
last ipedntns
Tens 11« t*st
Volatile* t«st specimen
Puncture test specimens
ts^-rSaT^ri
&*<«*«»•£?
S53«&3sS^Ssr
Te»r ttst sptdBcra
fet to »cil«
Figure 3 . Suggested pattern for cutting test .speclMns frco
semi crystalline Inmersed Uner samples. Note: To
avoid edge effects, cut specimens 1/8 - 1/4 Inch
1n from edge of 1tn«rsed sample.
9090 - 7
Revision 0
Date Scotcmoer 1986
1-7
-------
t
1
WO
1
1
N
_^/
1
1
w
t
1
n ...
LO
s
V
W • Widlh 0< njrrow «ction
L • L*ngrh o< narrow wciion
WO • W*Jin ovtrjll
LO • L*"5iri ovtr»ll
G • G*qe length
D • Duijnce beiwtf. y.Q\
0.25 in
US
0.625 inches
3.50 inches
1.00 i
2.00 i
Figure 4. Die for tensile dumbbell (nonreinforced liners! having the following
dimensions.
9090 - 8
Septemoer 1986
1-8
-------
9. Specific gravity, three specimens, ASTM 0792 Method A.
10. Ply adhesion, machine and transverse directions, two specimens each
direction for fabric reinforced liner materials only, ASTM D413
Machine Method, Type A — 180 degree peel.
11. Hydrostatic resistance test, ASTM 0751 Method A, Procedure 1.
7.3 For each test condition, cut five pieces of the lining material of a
size to fit the sample holder, or at least 8 1n. by 10 1n. The fifth sample
1s an extra sample. Inspect all samples for flaws and discard unsatisfactory
ones. Uner materials with fabric reinforcement require close Inspection to
ensure that threads of the samples are evenly spaced and straight at 90*.
Samples containing a fiber scrim support may be flood-coated along the exposed
edges with a solution recommended by the Hner manufacturer, or another
procedure should be used to prevent the scrim froo being directly exposed.
The flood-coating solution will typically contain 5-151 solids dissolved in a
solvent. The solids content can be the liner fonaula or the base polymer.
Measure the following:
1. Gauge thickness, in. — average of the four comers.
2. Mass, Ib. — to one-hundredth of a Ib.
*
3. Length, in. — average of the lengths of the two sides plus the
length measured through the liner center.
4. Width, 1n. — average of the widths of the two ends plus the width
measured through the Uner center.
NOTE: Do not cut these Uner samples Into the test specimen shapes shown
1n Figure 1, 2, or 3 at this time. Test specimens will be cut as
specified 1n 7.7, after exposure to the waste fluid.
7.4 Label the liner samples (e.g., notch or use uetal staples to
identify the sample) and hang 1n the waste fluid by a wire hanger or a weight.
Different Hner materials • should be Immersed 1n separate tanks to avoid
exchange of plastlclzers and soluble constituents when plastlcized uembranes
are being tested. Expose the liner samples to the stirred waste fluid held at
room temperature and at 50 + 2*C.
7.5 At the end of 30, 60, 90, and 120 days of exposure, remove one liner
sample from each test condition to determine the membrane's physical
properties (see Steps 7.6 and 7.7). Allow the Hner sample to cool in the
waste fluid until the waste fluid has a stable rooa teaperature. Wipe off as
much waste as possible and rinse briefly with water. Place wet sample 1n a
labeled polyethylene bag or aluminum' foil to prevent the sample from drying
out. The Hner sample should be tested as soon as possible after removal from
the waste fluid at room temperature, but 1n no case later than 24 hr after
removal.
9090 - 9
Revision 0
Date September 1986
1-9
-------
7,6 To test the Immersed sample, wipe off «ny remaining waste and rinse
with delonlzed water. Blot sample dry and measure the following as 1n Step
1. Gauge thickness, 1n.
2. Mass, Ib.
3. Length, In.
4. Width, 1n.
7.7 Perform the following tests on the exposed samples ( ee Steps 7.9 2
and 7.9.3 below for additional tests suggested for specific circumstancesj.
Tests for tear resistance and tensile properties ar* to be performed according
to the protocols referenced 1n Table 1. de-cut test specimens following
suggested cutting patterns. See Figure 1 for cutting patterns for
nonrelnforced liners, Figure 2 for cutting patterns for reinforced liners and
Figure 3 for semlcrystall1ne liners. '
1. Tear resistance, machine and transverse directions, three specimens
each direction for materials without fabric reinforcement. See Table 1 for
appropriate test method, the rtcomended test sped»en and speed of test and
the values to be reported. '
2. Puncture resistance, two specimens, FTKS 101C, Method 2065 See
Figure 1, 2, or 3, as applicable, for sample cutting patterns.
3. Tensile properties, eachlne and transverse directions three
specimens each direction. See Table 1 for appropriate test eethod the
recoimended test specimen and speed of test, and the values to be reported
See Figure 4 for tensile dumbbell cutting pattern dimensions for nonrelnforced
Uner sajnples.
4. Hardness, three specimens, Ouro A (Duro D 1f Duro A readinq 1s
greater than 80) AST* 2240. The hardness spedwn thickness for Duro A 1
1/4 in., and for Ouro 0 1s 1/8 In. The specimen dimensions are 1 in. by 1 1n.
5. Elongation at brtak. This test 1s to be performed only on wmbrane
the^lner that do not nav« * fabric or other nonelastomerlc support as part of
6. Modulus of elasticity, machine and transverse dictions two
edVe^'Hree0^ ^IcrystalHne Uner materials only, ASTH 0832
7. Volatlles content, SV 870, Appendix III-O.
8. Extractables content, SV 870, Appendix III-E.
9090 - 10
Revision p
Date Seotemoer 1986
1-10
-------
9. Ply adhesion, machine and transverse directions, two specimens each
direction for fabric rtlnforced liner materials only, AST* D413 Machine
Method, Type A — 180 degree peel.
10. Hydrostatic resistance test, AST* 0751 Method A, Procedure 1.
7.8 Results and reporting:
7.8.1 Plot the curve for each property over the t1»e period 0 to
120 days and display the sprtad 1n data points.
7.8.2 Report all raw, tabulated, and plotted data. Recommended
methods for collecting and presenting Information are described 1n the
documents listed under Step 6.1 and 1n related agency guidance manuals.
7.8.3 Summarize the raw test results as follows:
1. Percent change 1n thickness.
2. Percent change 1n mass.
3. Percent change 1n area (provide length and width dimensions).
4. Percent retention of physical properties.
5. Change, 1n points, of hardness reading.
6. The modulus of elasticity calculated 1n pounds-force per
square Inch.
7. Percent volatHes of unexposed and exposed liner material.
8. Percent extractables of unexposed and exposed Uner material.
9. The adhesion value, determined 1n accordance with ASTM 0413,
Section 12.2.
10. The pressure and time elapsed at the first appearance of
water through the flexible uembrane liner for the hydrostatic
resistance test.
7.9 The following additional procedures are suggested 1n specific
situations:
7.9.1 For the generation of a synthetic leachate, the Agency
suggests the use of the Toxldty Characteristic Leaching Procedure (TCLP)
that was proposed In the Federal Register on June 13, 1986, Vol. 51, No.
114, p. 21685.
7.9.2 For semi crystalline membrane liners, the Agency suggests the
determination of the potential for environmental stress cracking. The
9090 - 11
Revision
Date Septemoer 1986
1-11
-------
test that can be used to make this determination 1s either ASTH 01693 or
the National Bureau of Standards Constant Tensile Load. The evaluation
of the results should be provided by an expert 1n this field.
7.9.3 For field seams, the Agency suggests the determination of
seam strength 1n shear and peel •odes. To determine seam strength In
peel Bode, the test ASTM D413 can b« used. To determine seam strength 1n
shear node for nonrtlnforced FHLs, the test ASTH 03083 can be used, and
for reinforced FHLs, the test ASTH 0751, Grab Method, can be used at a
speed of 12 1n. per u1n. The evaluation of the results should be
provided by an expert In this field.
8.0 QUALITY CONTROL
8.1 Determine the mechanical properties of Identical nonlmmersed and
Immersed Hner samples 1n accordance with the standard methods for the
specific physical property test. Conduct mechanical property tests on
nonlmmersed and Immersed Hner samples prepared from the same sample or lot of
material 1n the same manner and run under Identical conditions. Test Hner
samples Immediately after they are rtaoved from the room temperature test
solution.
9.0 METHOD PERFORMANCE
9.1 No data provided.
10.0 REFERENCES
10.1 None required.
9090 - 12
Revision
Date September 1986
1-12
-------
TABLE 2. POLYMERS USED IN FLEXIBLE MEMBRANE LINERS
Thermoplastic Materials (TP)
CPE (Chlorinated polyethylene)*
A family of polymers produced by a chemical reaction of chlorine on
polyethylene. The resulting thermoplastic elastomers contain 25 to 451
chlorine by weight and 0 to 251 crystal Unity.
CSPE (Chlorosulfonated polyethylene)*
A family of polymers that art produced by the reaction of polyethylene
with chlorine and sulfur dioxide, usually containing 25 to 431 chlorine
and 1.0 to 1.41 sulfur. Chlorosulfonated polyethylene 1s also known as
hypalon.
E1A (Ethylene Interpolytner alloy)*
A blend of EVA and polyvinyl chloride resulting 1n a thermoplastic
elastomer.
PVC (Polyvlnyl chloride)*
A synthetic thermoplastic polymer Bade by polymerizing vinyl chloride
monomer or vinyl chloride/vinyl acetate monomers. Normally rigicf and
containing 501 of plastldzers.
PVC-CPE (Polyvlnyl chloride - chlorinated polyethylene alloy)*
A blend of polyvlnyl chloride and chlorinated polyethylene.
TN-PVC (Thermoplastic n1tr1le-oolyv1nyl cholorlde)*
An alloy of thermoplastic unvulcanlzed nltrlle rubber and polyvinyl
chloride.
Vulcanized Materials (XL)
Butyl rubber*
A synthetic rubber based on Isobutylene and a small amount of Isoprene to
provide sites for vulcanization.
*Also supplied reinforced with fabric.
9090 - 13
Revision
Date Septemoer 1986
1-13
-------
TABLE 2. (Continued)
EPOM (Ethylene propylene dlene nonomer)O
A synthetic elastomer based on ethylene, propylene, and a small amount of
nonconjugated dlene to provide sites for vulcanization.
CM (Cross-linked chlorinated polyethylene)
No definition available by EPA.
CO, ECO (Ep1cHlorohydr1n poly»ers)a
Synthetic rubber, Including two eplchlorohydrln-based elastomer? that are
saturated, h1gh-molecular-we1ght aliphatic polyethers with chloromethyl
side chains. The two types Include hoaopolymer (CO) and a copolymer of
eplchlorohydrln and ethylene oxide (ECO).
CR (Polych1oroprene)a
Generic name for a synthetic rubber based primarily on chlorobutadlene.
Polychloroprene 1s also known as neoprene.
Semi crystalline Materials (CX)
HOPE - (High-density polyethylene)
A polymer prepared by the low-pressure polymerization of ethylene as
the principal oonomer.
HOPE - A (High-density polyethylene/rubber alloy)
A blend of high-density polyethylene and rubber.
LLDPE (Liner low-density polyethylene)
A low-density polyethylene-produced by the copolymerlzatlon of ethylene
with various alpha oleflns 1n the presence of suitable catalysts.
PEL (Polyester elastomer)
A segmented thermoplastic copolyester elastooer containing recurring
long-chain ester units derived from dUarboxyllc adds and long-chain
glycols and short-chain ester units derived froa dlcarboxyHc adds and
low-nolecular-welght dlols.
*Also supplied reinforced with fabric.
bAlso supplied as a thermoplastic.
9090 - 14
Revision 0
Date September 1986
1-14
-------
TABLE 2. (Continued)
PE-EP-A (Polyethylene ethylene/propylene alloy)
A blend of polyethylene and ethylene and propylene polymer resulting 1n a
thermoplastic elastomer.
T-EPCH (Thermoplastic EPW)
An ethylene-propylene dlene nonoaer blend resulting 1n a thermoplastic
elastomer.
9090 - 15
Revision
Date September 1986
1-15
-------
KTHOO tO*0
CO»»»TII1WITT TCIT PO* •AITCS
/. 1
OBtsln ••«ol«
or •«»t«
7.2
form
•••ale* or
lln«r
7.3
Cut
ol«c«« of
lining ••t«ri«l
for ««cn t««t
condition
7.-
L«o«l
«o«el»«"«
«»oo««
to w««t« fluio
O
7.3
praoortl«t
3O a.y
7.6 To t««t
•mooaca
giugc
lingtn.
7.7
tl«t«
on «aeo««a
•••o!•*
••oort ana
O
( Stoo }
9090 - 16
Revision
September 1986
1-16
-------
APPENDIX J
-------
METHOD 9100
SATURATED HYDRAULIC CONDUCTIVITY.
SATURATED LEACMTECONDUCTiyiTYTlWD
INTRINSIC PERMEABILITY
1.0 INTRODUCTION
1.1 Scope and Application; This section presents methods available to
hydrogeologlsts and and geotechnlcal engineers for determining the saturated
hydraulic conductivity of earth materials and conductivity of soil liners to
leachate, as outlined by the Part 264 permitting rules for hazardous-waste
disposal facilities. In addition, a general technique to determine Intrinsic
permeability 1s provided. A cross reference between the applicable part of
the RCRA Guidance Documents and associated Part 264 Standards and these test
methods 1s provided by Table A.
1.1.1 Part 264 Subpart F establishes standards for ground water
quality monitoring and environmental performance. To demonstrate
compliance with these standards, a permit applicant must have knowledge
of certain aspects of the hydrogeology at the disposal facility, such as
hydraulic conductivity, 1n order to determine the compliance point and
monitoring well locations and 1n order to develop remedial action plans
when necessary.
1.1.2 In this report, the laboratory and field methods that are
considered the most appropriate to meeting the requirements of Part 264
are given 1n sufficient detail to provide an experienced hydrogeologlst
or geotechnlcal engineer with the methodology required to conduct the
tests. Additional laboratory and field methods that may be applicable
under certain conditions are Included by providing references to standard
texts and scientific journals.
1.1.3 Included 1n this report are descriptions of field methods
considered appropriate for estimating saturated hydraulic conductivity by
single well or borehole tests. The determination of hydraulic
conductivity by pumping or Injection tests 1s not Included because the
latter are considered appropriate for well field design purposes but may
not be appropriate for economically evaluating hydraulic conductivity for
the purposes set forth 1n Part 264 Subpart F.
1.1.4 EPA 1s not Including methods for determining unsaturated
hydraulic conductivity at this time because the Part 264 permitting
standards do not require such determinations.
1.2 Definitions; This section provides definitions of terms used 1n
the remainder of this report. These definitions are taken from U.S.
Government publications when possible.
9100 - 1
Revision
Date Septemoer 1986
j-l
-------
TABLE A
HYDRAULIC AND LINER CONDUCTIVITY DETERMINATION
METHODS FOR SURFACE IMPOUNDMENT,
WASTE PILE, AND LANDFILL COMPONENTS, AS CITED
IN RCRA GUIDANCE DOCUMENTS AND DESCRIBED IN SV-846
Guidance Cite1 Corresponding
Surface Impoundments Associated Regulation SW-84C Section
Soil liner hydraulic Guidance section D(2)(b)(l) 2.0
conductivity and D(2)(c)(l)/Sect1on
264.221(a),(b)
Soil liner leachate Guidance section D(2)(b)(2) 2.11
conductivity and D(2)(c)(2)
Leak detection Guidance section C(2)(a)/ 2.0
Section 264.222
Final cover drain Guidance section E(2)(d)(l) 2.0
layer Section 264.228
Final cover low Guidance section E(2)(e)(2)(A)/ 2.0
permeability layer Section 264.228
General hydrogeologlc 264 subpart F 3.0
site Investigation
1 RCRA Guidance Document: Surface Impoundments, Liner Systems, Final Cover,
and Freeboard Control. Issued July, 1982.
(continued on next page)
Revision 0
Date September 1986
-------
TABLE A (continued)
Waste Piles
Guidance Cite2
Associated Regulation
Corresponding
SW-846 Section
Soil Uner hydraulic
conductivity
Soil liner leachate
conductl v1 ty
Leak detection
system
Leachate collection
and renewal system
General hydrogeologlc
site Investigation
Guidance section D(2)(b)(1)
and D(2)(c)(1)/
Section 264.251(a)(1)
Guidance section 0(2)(b)(11)
and 0(2) (c) (11)
Guidance section C(2)(a)/
Section 264.252(a)
Guidance section C(2)(a)/
Section 264.251(a)(2)
264 subpart F
2.0
2.11
2.0
2.0
3.0
2 RCRA Guidance Document: Waste Pile Design, Liner Systems.
Issued July, 1982.
(continued on next page)
Revision 0
Date September 1986
J-3
-------
TABLE A (continued)
Landf111s
Guidance Cite3
Associated Regulation
Corresponding
SV-846 Section
Soil Uner hydraulic
conductivity
Soil Uner leachate
conductivity
Leak detection
systea
Leachate collection and
removal system
Final cover drain
layer
Final cover low
permeability layer
General hydrogeologlc
Guidance section D(2)(b)(l)/
Section 264. 301 (a) (1)
Guidance section 0(2)(b)(2)
Guidance section C(2)(a)/
Section 264.302(a)(3)
Guidance section C(2)(a)/
Section 264. 301 (a) (2)
Guidance section E(2)(d)(l)/
Section 264.310(a)(b)
Guidance section E(2)(e) (2) (A)
Section 264.310(a)(b)
264 subpart F
2.0
2.11
2.0
2.0
2.0
2.0
3.0
site Investigation
3 RCRA Guidance Document:
Issued July, 1982.
Landfill Design, Liner Systems and Final Cover.
J-4
Revision o
Date September 1986
-------
1.2.1 Units: This report uses consistent units 1n all equations.
The symbols used are:
Length • L,
Mass • H, and
Time • T.
1.2.2 Fluid potential or head (h): A Measure of the potential
energy required to move fluid from a point 1n the porous medium to a
reference point. For virtually all situations expected to be found 1n
disposal sites and 1n ground water systems, h 1s defined by the following
equation:
h • hp + hz (1)
where:
h 1s the total fluid potential, expressed as a height of
fluid above a reference datum, L;
hp, the pressure potential caused by the weight of fluid
above the point 1n question, L, 1s defined by hp » P/pg,
where:
P 1s the fluid pressure at the point In question, ML"1^2,
f 1s the fluid density at the prevailing temperature, ML'3,
and
g 1s the acceleration of gravity, LT*2; and
hz 1s the height of the point In question above the reference
datum, L.
By knowing hp and hz at two points along a flow path and by knowing
the distance between these points, the fluid potential gradient can be
determined.
1.2.3 Hydraulic potential or head: The fluid potential when water
1s the fluid.
1.2.4 Hydraulic conductivity: The fluid potential when water 1s
the fluid. The generic term, fluid conductivity, 1s discussed below in
1.2.5.
1.2.5 Fluid conductivity (K): Defined as the volume of fluid at
the prevailing density and dynamic viscosity .that w-111 move 1n a unit
time under a unit fluid potential gradient through a unit area measured
at right angles to the direction of flow. It 1s a property of both the
fluid and the porous medium as shown by the following equation:
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1C - ** i (2)
where:
K 1s the fluid conductivity, LT~1;
k 1$ the Intrinsic permeability, a property of the porous medium
alone, l>; and
u 1s the dynamic viscosity of the fluid at the prevailing
temperature, ML'* T"*.
The fluid conductivity of a porous material 1s also defined by Darcy's
law, which states that the fluid flux (q) through a porous medium 1s
proportional to the first power of the fluid potential across the unit
area:
q • $ • -« (3)
where:
q • the specific fluid flux, LT'l,
Q 1s the volumetric fluid flux, L3T'l,
A 1s the cross-sectional area, L2, and
I 1s the fluid potential gradient, L°.
Darcy's law provides the basis for all methods used to determine
hydraulic conductivity 1n this report. The range of validity of Darcy's
law 1s discussed 1n Section 1.5 (Lohman, 1972).
1.2.6 Leachate conductivity: The fluid conductivity when leachate
1s the fluid.
1.2.7 Aquifer: A geologic formation, group of formations, or part
of a formation capable of yielding a significant amount of ground water
to wells or springs (40 CFR 260.10).
1.2.8 Confining layer: By strict definition, a body of Impermeable
material strati graphically adjacent to one or more aquifers. In nature,
however, Its hydraulic conductivity may range from nearly zero to some
value distinctly lower than that of the aquifer. Its conductivity
relative to that of the aquifer 1t confines should be specified or
Indicated by a suitable modifier, such as 'slightly permeable" or
"moderately permeable* (Lohman, 1972).
1.2.9 Trans»1ss1v1ty, T [L2, T'l]: The rate at which water of the
prevailing kinematic viscosity 1s transmitted through a unit width of the
aquifer under a unit hydraulic gradient. Although spoken of as a
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property of the aquifer, the term also Includes the saturated thickness
of the aquifer and the properties of the fluid. It 1s equal to an
Integration of the hydraulic conductivities across the saturated part of
the aquifer perpendicular to the flow paths (Lohman, 1972).
1.3 Temperature and viscosity corrections; By using Equation (2),
corrections to conditions different from those prevailing during the test can
be Made. Two types of corrections can commonly be nude: a correction for a
temperature that varies from the test temperature, and a correction for fluids
other than that used for the test. The temperature correction 1s defined by:
(4)
where:
the subscript f refers to field conditions, and
the subscript t refers to test conditions.
Most temperature corrections are necessary because of the dependence of
viscosity on temperature. Fluid density variations caused by temperature
changes are usually very small for most liquids. The temperature correction
for water can be significant. Equation (4) can also be used to determine
hydraulic conductivity 1f fluids other than water are used. It 1s assumed,
however, when using Equation (4) that the fluids used do not alter the
Intrinsic permeability of the porous medium during the test. Experimental
evidence shows that this alteration does occur with a wide range of organic
solvents (Anderson and Brown, 1981). Consequently, 1t 1s recommended that
tests be run using fluids, such as leachates, that might occur at each
particular site. Special considerations for using non-aqueous fluids are
given 1n Section 3.3 of this report.
1.4 Intrinsic permeability (k): Rearrangement
a definition of Intrinsic permeability:
of Equation 2 results 1n
(5)
r*
Since this 1s a property of the medium alone, 1f fluid properties change, the
fluid conductivity must also change to keep the Intrinsic permeability a
constant. By using measured fluid conductivity, and values of viscosity and
density for the fluid at the test temperature, Intrinsic permeability can be
determined.
1.5 Range of validity of
Oarcy's law; Determination of fluid
conductivities using both laboratoryand field methods requires assuming the
validity of Darcy's law. Experimental evidence has shown that deviations from
the linear dependence of fluid flux on potential gradient exist for both
extremely low and extremely high gradients (HUlel, 1971; Freeze and Cherry,
1979). The lower limits are the result of the existence of threshold
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gradients required to Initiate flow (Swartzendruber, 1962). The upper limits
to the validity of Darcy's law can be estimated by the requirements that the
Reynolds number, Re, 1n most cases be kept below 10 (Bear, 1972). The
Reynolds number 1s defined by:
Re - * (6)
where:
d 1s some characteristic dimension of the system, often represented
by the median grain size diameter, OSQ, (Bouwer, 1978), and
q 1s the fluid flux per unit area, U-l.
For most field situations, the Reynolds number 1s less than one, and Darcy's
law 1s valid. However, for laboratory tests 1t may be possible to exceed the
range of validity by the Imposition of high potential gradients. A rough
check on acceptable gradients can be made by substituting Darcy's law 1n
Equation (6) and using an upper limit of 10 for Re:
where:
K 1s the approximate value of fluid conductivity determined at
gradient I.
A more correct check on the validity of Darcy's law or the range of gradients
used to determine fluid conductivity 1s performed by measuring the conduc-
tivity at three different gradients. If a plot of fluid flux versus gradient
1s linear, Darcy's law can be considered to be valid for the test conditions.
1.6 Method Classification; This report classifies methods of
determining fluidconductivityInto two divisions: laboratory and field
methods. Ideally, and whenever possible, compliance with Part 264 disposal
facility requirements should be evaluated by using field methods that test the
materials under 1n-$1tu conditions. Field methods can usually provide more
representative values than laboratory methods because they test a larger
volume of material, thus Integrating the effects of macrostructure and
heterogeneities. However, field methods presently available to determine the
conductivity of compacted fine-grained materials 1n reasonable times require
the tested Interval to be below a water table or to be fairly thick, or
require excavation of the material to be tested at some point 1n the test.
The Integrity of liners and covers should not be compromised by the
Installation of boreholes or piezometers required for the tests. These
restrictions generally lead to the requirement that the fluid conductivity of
Uner and cover materials must be determined 1n the laboratory. The transfer
value of laboratory data to field conditions can be maximized for liners and
covers because 1t 1s possible to reconstruct relatively accurately the desired
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field conditions 1n the laboratory. However, field conditions that would
alter the values determined 1n the laboratory need to be addressed 1n permit
applications. These conditions Include those that would Increase conductivity
by the formation of mlcrocracks and channels by repeated wetting and drying,
and by the penetration of roots.
1.6.1 Laboratory methods are categorized 1n Section 2.0 by the
methods used to apply the fluid potential gradient across the sample.
The discussion of the theory, measurement, and computations for tests run
under constant and falling-head conditions 1s followed by a detailed
discussion of tests using specific types of laboratory apparatus and the
applicability of these tests to remolded compacted, fine-grained
unconpacted, and coarse-grained porous media. Section 2.3 provides a
discussion of the special considerations for conducting laboratory tests
using non-aqueous penneants. Section 2.10 gives a discussion of the
sources of error and guidance for establishing the precision of
laboratory tests. Laboratory methods may be necessary to measure
vertical fluid conductivity. Values from field tests reflect effects of
horizontal and vertical conductivity.
1.6.2 Field methods are discussed 1n Section 3.0 and are limited to
those requiring a single bore hole or p1ezo«eter. Methods requiring
multiple bore holes or piezometers and areal methods are Included by
reference. Because of the difficulties 1n determining fluid conductivity
of 1n-place Uner and cap materials under field conditions without
damaging their Integrity, the use of field methods for fine-grained
materials will be generally restricted to naturally occurring materials
that may serve as a barrier to fluid movement. Additional field methods
are referenced that allow determination of saturated hydraulic
conductivity of the unsaturated materials above the shallowest water
table. General methods for fractured media are given 1n Section 3.8. A
discussion of the Important considerations 1n well Installation,
construction, and development 1s Included as an Introduction to Section
3.0.
2.0 LABORATORY METHODS
2.1 Sample collection for laboratory method; To assure that a
reasonable assessment 1s made of fieldconditionsit a disposal site, a site
Investigation plan should be developed to direct sampling and analysis. This
plan generally requ1res$the professional judgement of an experienced
hydrogeologlst or geotechnlcal engineer. General guidance Is provided for
plan development 1n the Guidance Manual for Preparation of a Part 264 land
Disposal Facility Permit Application (EPA. 1n press).The points listed below
should be followed:
o The hydraulic conductivity of a soil Uner should be determined either
from samples that are processed to simulate the actual Uner, or from an
undisturbed sample of the complete Uner.
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o To obtain undisturbed samples, the thin-walled tube sampling method (ASTM
Method * 01587-74) or a similar method may be used. Samples
representative of each 11ft of the Uner should be obtained, and used In
the analyses. If actual undisturbed samples are not used, the soil used
1n Uner construction «ust be processed to represent accurately the
liner's Initial water content and bulk density. The method described 1n
Section 2.7.3 or ASTM Method #0698-70 (ASTM, 1978) can be used for this
purpose.
o For purpose of the general site Investigation, the general techniques
presented In ASTM method #0420-69 (ASTM, 1978) should be followed. This
reference establishes practices for soil and rock Investigation and
sampling, and Incorporates various detailed ASTM procedures for
Investigation, sampling, and material classification.
2.2 Constant-head methods; The constant-head method 1s the simplest
method of determining hydraulic conductivity of saturated soil samples. The
concept of the constant-head method 1s schematically Illustrated In Figure 1.
The Inflow of fluid 1s maintained at a constant head (h) above a datum and
outflow (Q) 1s measured as a function of time (t). Using Carey's law, the
hydraulic conductivity can be determined using the following equation after
the outflow rate has become constant:
K • QL/hA, (8)
where:
K • hydraulic conductivity, LT'l;
I • length of sample, I;
A « cross-sectional area of sample, t2;
Q • outflow rate, L3T'l; and
h » fluid head difference across the sample, L.
Constant-head methods should be restricted to tests on media having high fluid
conductivity.
2.3 Falling-head methods; A schematic diagram of the apparatus for the
falling-head method 1s shown 1n Figure 2. The head of Inflow fluid decreases
from Jij to h£ as a function of time (t) 1n a standplpe directly connected to
the specimen. The fluid head at the outflow Is maintained constant. The
quantity of outflow can be measured as well as the quantity of Inflow. For
the setup shown In Figure 2a, the hydraulic conductivity can be determined
using the following equation:
0
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Date September 1986
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ov m* to w
TO MAINTAIN
CONSTANT M t A 0
OMAOUATfe
e Y LIN o i m
Figure 1.—Principle of the constant head method
j-ll
1
Revision 0
Date September
1986
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OV«*ftO*
i-4fii
to)
-»<^)3
OVUMLOtt
-Z-
to)
Figure 2.—Principle of the falling head method
using a small (a) and large (b) standpipe
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Revision p
Date September l$6g
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where:
a • the cross-sectional area of the standplpe, L2;
A • the cross-sectional area of the specimen, L2;
L • the length of the specimen, L; and
t • elapsed time from tj to tj, T.
For the setup 1n Figure 2b, the term a/A 1n Equation (9) 1s replaced by 1.0.
Generally, falling-head methods are applicable to fine-grained soils because
the testing time can be accelerated.
2.4 General test considerations;
2.4.1 Fluid supplies to be used: For determining hydraulic
conductivity and leachate conductivity, the supplies of permeant fluid
used should be de-a1red. A1r coming out of solution 1n the sample can
significantly reduce the measured fluid conductivity. Deal ring can be
achieved by boiling the water supply under a vacuum, bubbling helium gas
through the supply, or both.
2.4.1.1 Significant reductions In hydraulic conductivity can
also occur 1n the growth and multiplication of microorganisms
present 1n the sample. If 1t 1s desirable to prevent such growth, a
bacterldde or fungicide, such as 2000 ppm formaldehyde or 1000 ppm
phenol (Olsen and Daniel, 1981), can be added to the fluid supply.
2.4.1.1 Fluid used for determining hydraulic conductivity 1n
the laboratory should never be distilled water. Native ground water
from the aquifer underlying the sampled area or water prepared to
simulate the native ground water chemistry should be used.
2.4.2 Pressure and Fluid Potential Measurement: The equations 1n
this report are all dimensionally correct; that 1s, any consistent set of
units may be used for length, mass, and time. Consequently, measurements
of pressure and/or fluid potential using pressure gages and manometers
must be reduced to the consistent units used before applying either
Equation 8 or 9. Pressures or potentials should be measured to within a
few tenths of one percent of the gradient applied across the sample.
2.5 Constant-head test with conventional permeameter;
2.5.1 Applicability: This method covers the determination of the
hydraulic conductivity of soils by a constant-head method using a
conventional permeameter. This method 1s recommended for disturbed
coarse-grained soils. If this method 1s to be used for fine-grained
soils, the testing time may be prohibitively long. This method was taken
from the Engineering and Design, Laboratory Soils Testing Manual (U.S.
Army, 1980). It parallels ASTM Method D2434-68 (ASTM.1978). The ASTM
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Date September 1986
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method gives extensive discussion of sample preparation and applicability
and should be reviewed before conducting constant-head tests. Larabe
(1951) provides additional Information on sample preparation and
equipment procedures.
2.5.2 Apparatus: The apparatus 1s shown schematically 1n Figure 3.
It consists of the following:
1. A permeaaeter cylinder having a diameter at least 8 times the
diameter of the largest particle of the material to be tested;
2. Constant-head filter tank;
3. Perforated metal disks and circular wire to support the sample;
4. Filter materials such as Ottawa sand, coarse sand, and gravel of
various gradations;
5. Manometers connected to the top and bottom of the sample;
6. Graduated cylinder, 100-mL capacity;
7. Thermometer;
8. Stop watch;
9. Deal red water;
10. Balance sensitive to 0.1 gram; and
11. Drying oven.
2.5.3 Sample preparation:
1. Oven-dry the sample. Allow 1t to cool, and weigh to the nearest
0.1 g. Record the oven-dry weight of material. The amount of
material should be sufficient to provide a specimen 1n the
permeameter having a minimum length of about one to two times
the diameter of the specimen.
2. Place a wire screen, with openings small enough to retain the
specimen, over a perforated disk near the bottom of the
permeameter above the Inlet. The screen opening should be
approximately equal to the 10 percent size of the specimen.
3. Allow deal red water to enter the water Inlet of the permearaeter
to a height of about 1/2 1n. above the bottom of the screen,
taking care that no air bubbles are trapped under the screen.
J 14 Revision
Date September 1986
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0* • Atr««
C*niitf
N«»« Teak
fc, hj
I
}
=
m
V •!••
Ah
^1
• t»n
i
fi
z
•
• »
i i
••
~
1
I*
-
•
t\
M t
••MM
S*r*»n.
<
V •!••
H •
O ucn «r|t
(a)
constant head
W •*!•
(b)
falling head
Figure 3.— Apparatus setup for the constant head (a)
and falling head (b) methods.
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Revision 0
Date September 1986
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*. Mix the material thoroughly and place 1n the permeameter to
avoid segregation. The material should be dropped Just at the
water surface, keeping the water surface about 1/2 1n. above the
top of the soil during placement. A funnel or a spoon 1s
convenient for this purpose.
5. The placement procedure outlined above will result 1n a
saturated spedsen of uniform density although 1n a relatively
loose condition. To produce a higher density In the specimen,
the sides of the permeaaeter containing the soil sample are
tapped uniformly along Us c1rcumference and length with a
rubber mallet to produce an Increase 1n density; however,
extreme caution should be exercised so that fines are not put
Into suspension and segregated within the sample. As an
alternative to this procedure, the specimen may be placed using
an appropriate sized funnel or spoon. Compacting the specimen
1n layers 1s not recommended, as a film of dust which might
affect the permeability results may be formed at the surface of
the compacted layer. After placement, apply a vacuum to the top
of the specimen and permit water to enter the evacuated specimen
through the base of the permeameter.
6. After the specimen has been placed, weigh the excess material,
1f any, and the container. The specimen weight 1s the
difference between the original weight of sample and the weight
of the excess material. Care must be taken so that no material
1s lost during placement of the specimen. If there 1s evidence
that material has been lost, oven-dry the specimen and weigh
after the test as a check.
7. Level the top of the specimen, cover with a wire screen similar
to that used at the base, and fill the remainder of the
permeameter with a filter material.
8. Measure the length of the specimen, Inside diameter of the
permeameter, and distance between the centers of the manometer
tubes (L) where they enter the permeameter.
2.5.4 Test procedure:
1. Adjust the height of the constant-head tank to obtain the
desired hydraulic gradient. The hydraulic gradient should be
selected so that the flow through the specimen 1s laminar.
Hydraulic gradients ranging from 0.2 to 0.5 are recommended.
Too high a hydraulic gradient may cause turbulent flow and also
result In piping of soils. In general, coarser soils require
lower hydraulic gradients. See Section 1.5 for further
discussion of excessive gradients.
2. Open valve A (see Figure 3a) and record the Initial piezometer
readings after the flow has become stable. Exercise care 1n
building up heads 1n the permeameter so that the specimen 1s not
disturbed.
6
•J-16 Revision 0
Date September 1986
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3. After allowing a few minutes for equilibrium conditions to be
reached, measure by means of a graduated cylinder the quantity
of discharge corresponding to a given time Interval. Measure
the plezonetrlc heads (hi and h£) and the water temperature 1n
the pemeaneter.
4. Record the quantity of flow, piezometer readings, water
temperature, and the time Interval during which the quantity of
flow was measured.
2.5.5 Calculations: By plotting the accumulated quantity of
outflow versus time on rectangular coordinate paper, the slope of the
linear portion of the curve can be determined, and the hydraulic
conductivity can be calculated using Equation (8). The value of h 1n
Equation (8) 1s the difference between hj and h£.
2.6 Falling-head test with conventional permeameter;
2.6.1 Applicability: The falling-head test can be used for all
soil types, but 1s usually most widely applicable to materials having low
permeability. Compacted, remolded, fine-grained soils can be tested with
this method. This method presented 1s taken from the Engineering and
Design, Laboratory Soils Testing Manual (U.S. Army, 1980).
2.6.2 Apparatus: The schematic diagram of the falling-head
permeaneter 1s shown 1n Figure 3b. The permeameter consists of the
following equipment:
1. Penneameter cylinder, a transparent acrylic cylinder having a
diameter at least 8 times the diameter of the largest particles;
2. Porous disk;
3. Wire screen;
4. Filter materials;
5. Manometer;
6. Timing device; and
2.6.3 Sample Preparation: Sample preparation for coarse-grained
soils 1s similar to that described previously 1n Section 2.4.3. For
fine-grained soils, samples are compacted to the desired density using
methods described In ASTM Method 0698-70.
2.6.4 Test Procedure:
1. Measure and record the height of the specimen, L, and the cross-
sectional area of the specimen, A.
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Date September 1986
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2. With valve B open (see Figure 3b), crack valve A, and slowly
bring the water level up to the discharge level of the
perneaaeter.
3. Raise the head of water In the standplpe above the discharge
level of the permeameter. The difference 1n head should not
result 1n an excessively high hydraulic gradient during the
tist. Close valves A and B.
4. Begin the test by opening valve B. Start the timer. As the
water flows through the specimen, measure and record the height
of water In the standplpe above the discharge level, hi, at time
ti, and the height of water above the discharge level, hj at
time t2.
2.6.5 Calculations: From the test data, plot the logarithm of head
versus time on rectangular coordinate paper, or use semi-log paper. The
slope of the linear part of the curve 1s used to determine
Iogio(hi/h2)/t. Calculate the hydraulic conductivity using Equation (9).
2.7 Modified compaction perraeameter method;
2.7.1 Applicability: This method can be used to determine the
hydraulic conductivity of a wide range of materials. The method 1s
generally used for remolded fine-grained soils. The method 1s generally
used under constant-head conditions. The method was taken from Anderson
and Brown, 1981, and EPA (1980). It should be noted that this method.
method of Section 2.9.
2.7.2 Apparatus: The apparatus 1s shown 1n Figure 4 and consists
of equipment and accessories as follows:
1. Soil chamber, a compaction mold having a diameter 8 times larger
than the diameter of the largest particles (typically, ASTM
standard mold, Number CN405, 1s used);
2. Fluid chamber, a compaction mold sleeve having the same diameter
as the soil chamber;
3. 2-kg hammer;
4. Rubber rings used for sealing purposes;
5. A coarse porous stone having higher permeability than the tested
sample;
6. Regulated source of compressed air; and
7. Pressure gage or manometer to determine the pressure on the
fluid chamber.
J-18
Revision
Date September 1986
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TO REGULATED PRESSURE SOURCE AND
PRESSURE CAGE OR MANOMETER USED TO
MEASURE H
A
-U4
'"]—— PRESSURE RELEASE VALVE
TOP PLATE
t
i
s
§
1
b
^
\^
FLUID CHAMBER
•• •- :••• •• ..••..• • • - .4
-./. ••..••••;--••. -:-..-
•.';-.;-;'.-:-v-':.;.--V: '
. . • SOIL CHAMBER ''.
•'„'. ''.'.•*••••.''•'"• '* -
h
t *
^
|
1
X
,\
0
f
d
s^
— 1
*
'•
.
•
^H
-.
M
o
5
OH/
RUBBER "0' RING SEALS
EASE PLATE
L— POROUS STONE
OUTFLOW TO VOLUMETRIC MEASURING DEVICE.
PRESSURE SHOULD IE ATMOSPHERIC OR ZERO
GAGE PRESSURE
Figure 4.—
Modified compaction ptnn«a»*ttr.
Not*: h in Equation 8 is the difference
between the regulated inflow pressure
and the outflow pressure. Source:
Anderson and Brown, 1981.
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Date September 1986
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2.7.3 Staple preparation:
1. Obtain sufficient representative soil sample. A1r dry the
sample at room temperature. Do not oven dry.
2. Thoroughly i1x the selected representative sample with water to
obtain a desired Moisture content.
3. Compact the sample to the desired density within the mold using
the method described as part of ASTM Method 0698-70.
4. Level the surface of the compacted sample with straight edge,
weigh and determine the density of the sample.
5. Measure the length and diameter of the sample.
6. Assemble the apparatus, make sure that there are no leaks, and
then connect the pressure line to the apparatus.
2.7.4 Test procedure:
1. Place sufficient volume of water 1n the fluid chamber above the
soil chamber.
2. Apply air pressure gradually to flush water through the sample
until no air bubblesTnthe outflow are observed. For fine-
grained soils, the saturation may take several hours to several
days, depending on the applied pressure.
3. After the sample 1s saturated, measure and record the quantity
of outflow versus time.
4. Record the pressure reading (h) on the top of the fluid chamber
when each reading 1s made.
5. Plot the accumulated quantity of outflow versus time on
rectangular coordinate paper.
6. Stop taking readings as soon as the linear position of the curve
1s defined.
2.7.5 Calculations: The hydraulic conductivity can be calculated
using Equation (8).
2.8 Tr1axial-cell method with back pressure;
2.8.1 Applicability: This method 1s applicable for all soil types,
but especially for fine-grained, compacted, cohesive soils 1n which full
fluid saturation of the sample Is difficult to achieve. Normally, the
test 1s run under constant-head conditions.
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Date September 1986
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2.8.2 Apparatus: The apparatus 1s similar to conventional trlaxlal
apparatus. The schematic diagram of this apparatus 1s shown 1n Figure 5.
2.8.3 Sample preparation: Disturbed or undisturbed samples can be
tested. Undisturbed samples oust be trlnmed to the diameter of the top
cap and base of the trlaxlal cell. Disturbed samples should be prepared
1n the mold using either kneading compaction for fine-grained soils, or
by the pouring and vibrating method for coarse-grained soils, as
discussed 1n Section 2.5.3.
2.8.4 Test procedure:
1. Measure the dimensions and weight of the prepared sample.
2. Place one of the prepared specimens on the base.
3. Place a rubber membrane 1n a membrane stretcher, turn both ends
of the membrane over the ends of the stretcher, and apply a
vacuum to the stretcher. Carefully lower the stretcher and
membrane over the specimen. Place the specimen and release the
vacuum on the membrane stretcher. Turn the ends of the membrane
down around the base and up around the specimen cap and fasten
the ends with 0-r1ngs.
4. Assemble the trlaxlal chamber and place 1t In position 1n the
loading device. Connect the tube from the pressure reservoir to
the base of the trlaxlal chamber. With valve C (see Figure 5)
on the pressure reservoir closed and valves A and B open,
Increase the pressure Inside the reservoir, and allow the
pressure fluid to fill the trlaxlal chamber. Allow a few drops
of the pressure fluid to escape through the vent valve (valve 8)
to Insure complete filling of the chamber with fluid. Close
valve A and the vent valve.
5. Place saturated filter paper disks having the same diameter as
that of the specimen between the specimen and the base and cap;
these disks will also facilitate removal of the specimen after
the test. The drainage lines and the porous Inserts should be
completely saturated with deal red water. The drainage lines
should be as short as possible and made of thick-walled, small-
bore tubing to Insure minimum elastic changes 1n volume due to
changes 1n pressure. Valves 1n the drainage lines (valves E, F,
and 6 In Figure 5) should preferably be of a type which will
cause no discernible change of Internal volume when operated.
While mounting the specimen 1n the compression chamber, care
should be exercised to avoid entrapping any air beneath the
membrane or between the specimen and the base and cap.
J 21 Revision
Date Septemoer 1986
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•mt.it*
Figure 5.—Schematic diagram of typical triaxial compression
apparatus for hydraulic conductivity tests with
back pressure.
Source: D.S. Army Corps of Engineers, 1970
J-22
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Date September 1986
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6. For ease and uniformity of saturation, as well as to allow
volume changes during consolidation to be neasured with the
burette, specimens should be completely saturated before any
appreciable consolidation 1s permitted; therefore, the
difference between the chamber pressure and the back pressure
should not exceed 5 ps1 during the saturation phase. To Insure
that a specimen 1s not prestressed during the saturation phase,
the back pressure must be applied 1n small Increments, with
adequate time between Increments to permit equalization of pore
water pressure throughout the specimen.
7. With all valves closed, adjust the pressure regulators to a
chamber pressure of about 7 ps1 and a back pressure of about 2
ps1. Now open valve A to apply the preset pressure to the
chamber fluid and simultaneously open valve F to apply the back
pressure through the specimen cap. Immediately open valve G and
read and record the pore pressure at the specimen base. When
the measured pore pressure becomes essentially constant, close
valves F and G and record the burette reading.
8. Using the technique described 1n Step 3, Increase the chamber
pressure and the back pressure 1n Increments, maintaining the
back pressure at about 5 ps1 less than the chamber pressure.
The size of each Increment might be 5, 10, or even 20 ps1,
depending on the compressibility of the soil specimen and the
magnitude of the desired consolidation pressure. Open valve G
and measure the pore pressure at the base Immediately upon
application of each Increment of back pressure and observe the
pore pressure until 1t becomes essentially constant. The time
required for stabilization of the pore pressure may range from a
few minutes to several hours depending on the permeability of
the soil. Continue adding Increments of chamber pressure and
back pressure until, under any Increment, the pore pressure
reading equals the applied back pressure Immediately upon
opening valve G.
9. Verify the completeness of saturation by closing valve F and
Increasing the chamber pressure by about 5 ps1. The specimen
shall not be considered completely saturated unless the Increase
1n pore pressure Immediately equals the Increase 1n chamber
pressure.
10. When the specimen 1s completely saturated, Increase the chamber
pressure with the drainage valves closed to attain the desired
effective consolidation pressure (chamber pressure minus back
pressure). At zero elapsed time, open valves E and F.
11. Record time, dial Indicator reading, and burette reading at
elapsed times of 0, 15, and 30 sec, 1, 2, 4, 8, and 15 m1n, and
1, 2, 4, and 8 hr, etc. Plot the dial Indicator readings and
J-23 Revision 0
Date September 1986
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burette readings on an arithmetic scale versus elapsed time on a
log scale. When the consolidation curves Indicate that primary
consolidation 1s complete, close valves E and F.
12. Apply a pressure to burette B greater than that 1n burette A.
The difference between the pressures 1n burettes B and A 1s
equal to the head loss (h); h divided by the height of the
specimen after consolidation (L) Is the hydraulic gradient. The
difference between the two pressures should be kept as small as
practicable, consistent with the requirement that the rate of
flow be large enough to make accurate measurements of the
quantity of flow within a reasonable period of time. Because
the difference 1n the two pressures may be very small 1n
comparison to the pressures at the ends of the specimen, and
because the head loss must be maintained constant throughout the
test, the difference between the pressures within the burettes
must be measured accurately; a differential pressure gage 1s
very useful for this purpose. The difference between the
elevations of the water within the burettes should also be
considered (1 1n. of water • 0.036 ps1 of pressure).
13. Open valves D and F. Record the burette readings at any zero
elapsed time. Make readings of burettes A and B and of
temperature at various elapsed times (the Interval between
successive readings depends upon the permeability of the soil
and the dimensions of the specimen). Plot arithmetically the
change 1n readings of both burettes versus time. Continue
making readings until the two curves become parallel and
straight over a sufficient length of time to determine
accurately the rate of flow as Indicated by the slope of the
curves.
2.8.5 Calculations: The hydraulic conductivity can be calculated
using Equation (8).
2.9 Pressure-chamber permeameter method;
2.9.1 Applicability: This method can be used to determine
hydraulic conductivity of a wide range of soils. Undisturbed and
disturbed samples can be tested under falling-head conditions using this
method. This method 1s also applicable to both coarse- and fine-grained
soils, Including remolded, fine-grained materials.
2.9.2 Apparatus: The apparatus, shown 1n Figure 6, consists of
1. Pressure chamber;
2. Standplpe;
3. Specimen cap and base; and
4. Coarse porous plates.
J~24 Revision 0
Date September 1986
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Figure 6.—
Pressure chamber for hydraulic
conductivity.
Source: U.S. Amy Corps of Engineers,
1980.
J-25
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Date September 1986
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The apparatus 1s capable of applying confining pressure to simulate field
stress conditions.
2.9.3 Sample preparation: The sample preparation of disturbed and
undisturbed conditions can be prepared 1n the chamber and enclosed within
the rubber membrane, as discussed 1n Section 2.8.4.
2.9.4 Test procedure:
1. By adjusting the leveling bulb, a confining pressure 1s applied
to the sample such that the stress conditions represent field
conditions. For higher confining pressure, compressed air may
be used.
2. Allow the sample to consolidate under the applied stress until
the end of primary consolidation.
3. Flush water through the sample until no Indication of air
bubbles 1s observed. For higher head of water, compressed air
may be used.
4. Adjust the head of water to attain a desired hydraulic gradient.
5. Measure and record the head drop 1n the standplpe along with
elapsed time until the plot of logarithm of head versus time 1s
linear for more than three consecutive readings.
2.9.5 Calculations: The hydraulic conductivity can be determined
using Equation (9).
2.10 Sources of error for laboratory test for hydraulic conductivity;
There are numerouspotentialsourcesoferror1n laboratorytests for
hydraulic conductivity. 'Fixed-wall permeameters may have problems with
sldewall leakage, causing higher values of hydraulic conductivity. Flexlble-
menfcrane permeameters may yield m1slead1ngly low values for hydraulic
conductivity when testing with a leachate that causes contraction and
shrinkage cracks 1n the sample because the membrane shrinks with the sample.
Table B summarizes sooe potential errors that can occur. 01 sen and Daniel
(1981) provide a more detailed explanation of sources of these errors and
methods to minimize them. If the hydraulic conductivity does not fall within
the expected range for the soil type, as given 1n Table C, the measurement
should be repeated after checking the source of error 1n Table B.
J-26
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Date September 1986
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TABLE B
SUMMARY OF PUBLISHED DATA ON POTENTIAL ERRORS
IN USING DATA FROM
LABORATORY PERMEABILITY TESTS ON SATURATED SOILS
Measured K
Source of Error (References)
Too Low or Too High?
1. Voids formed 1n sample preparation
(01 sen and Daniel, 1981).
2. Smear zone formed during trInning
(01 sen and Daniel, 1981).
3. Use of distilled water as a
penneant (Fireman, 1944; and
Wilkinson, 1969).
4. A1r 1n sample (Johnson, 1954)
5. Growth of micro-organisms
(Allison, 1947).
6. Use of excessive hydraulic
gradient (Schwartiendruber, 1968;
and Mitchell and Younger, 1967).
7. Use of temperature other than the
test temperature.
8. Ignoring volume change due to
stress change, with no confining
pressure used.
9. Performing laboratory rather
than 1n-s1tu tests (01 sen and
Daniel, 1981).
10. Impedance caused by the test
apparatus, Including the
resistance of the screen or
porous stone used to support
the sample.
High
Low
Low
Low
Low
Low or High
Varies
High
Usually Low
Low
J-27
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TABLE C
HYDRAULIC CONDUCTIVITIES ESTIMATED FROM GRAIN-SIZE DESCRIPTIONS
(In Feet Per Day)
Grain-Size Class or Range
From Sample Description
Degree of Sorting
Poor Moderate Well
Silt Content
Slight Moderate High
Fine-Grained Materials
Clay
S1lt, clayey
S1U, slightly sandy
S1lt, moderately sandy
S1lt, very sandy
Sandy silt
S1Hy sand
Sands and gravels(*)
Less than .001
1 - 4
5
7 - 8
9-11
11
13
Very fine sand
Very fine to fine sand
Very fine to medium sand
Very fine to coarse sand
Very fine to very coarse sand
Very fine sand to fine gravel
Very fine sand to medium gravel
Very fine sand to coarse gravel
Fine sand
Fine to medium sand
Fine to coarse sand
Fine to very coarse sand
Fine sand to fine gravel
Fine sand to medium gravel
Fine sand to coarse gravel
Medium sand
Medium to coarse sand
Medium to very coarse sand
Medium sand to fine gravel
Medium sand to medium gravel
Medium sand to coarse gravel
Coarse sand
Coarse to very coarse sand
Coarse sand to fine gravel
Coarse sand to medium gravel
Coarse sand to coarse gravel
13
27
36
48
59
76
99
128
27
53
57
70
88
114
145
67
74
84
103
131
164
80
94
116
147
184
20
27
41-47
-
-
-
-
-
40
67
65-72
.
-
-
-
80
94
98-111
-
•
-
107
134
136-156
-
*
27
-
•
-
•
-
-
-
53
.
.
«>
-
-
94
«B
.
-
•
-
134
.
.
•>
-
23
24
32
40
51
67
80
107
33
48
53
60
74
94
107
64
72
71
84
114
134
94
94
107
114
134
19
20
27
31
40
52
66
86
27
39
43
47
59
75
87
51
57
61
68
82
108
74
75
88
94
100
13
13
21
24
29
38
49
64
20
30
32
35
44
57
72
40
42
49
52
66
82
53
57
68
74
92
Reduce by 10 percent 1f grains are subangular.
Source: Lappala (1978).
(continued)
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Date September 1986
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14
A
•nd
C
12
10
10
90 IOO
900 1000
-u-Jj JO
9000
Figure 10. —Curves defining coefficients A, B,
and C in equations 13 and 14 as
a function of the ratio L/rv.
Source: Bower and Rice, 1976.
J-29
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Date September1555
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where rc, r-, l», t, Y, and K have been previously defined or are
defined 1n Figure 8a. Y0 1s the value of Y Immediately after
withdrawal of the slug of water. The tern I 1s an effective radius
for wells that do not fully penetrate the aquifer that 1s computed
using the following equation given by Bouwer and R1ce (1976):
If the quantity (Ho-l^/r*) 1s larger than 6, a value of 6 should be
used.
For wells that completely penetrate the aquifer, the following
equation 1s used:
(Bouwer, 1976). The values of the constants A, B, and C are given
by Figure 10 (Bouwer and R1ce, 1976).
For both cases, straight-! 1ne portions of plots of the logarithm of
Y or Y0/Y against time should be used to determine the slope,
(In Y0/Y)/t.
Additional methods for tests under unconflned conditions are
summarized by Bower (1976) on pages 117-122. These Methods are
modifications of the cased-well method described above that apply
either to an uncased borehole or to a well or piezometer 1n which
the diameter of the casing and the borehole are the same (Figures 9b
and 9c.)
3.4.3.4 Sources of error; The method assumes that flow of
water from above 1s negligible. If this assumption cannot be met,
the conductivities may be 1n error. Sufficient flow from the
unsaturated zone by drainage would result 1n a high conductivity
value. Errors caused by measuring water levels and recording time
are similar to those discussed 1n Sections 3.4.1.4 and 3.4.2.4.
3.5 Multiple well tests; Hydraulic conductivity can also be determined
by conventional pumping tests 1n which water 1s continuously withdrawn or
Injected using one well, and the water-level response 1s measured over time 1n
or near more observation wells. The observation wells must be screened 1n the
same strata as the Injection or pumping well. These methods generally test
larger portions of aquifers than the single well tests discussed 1n Section
3.4. For some circumstances these tests may be appropriate 1n obtaining data
to use 1n satisfying requirements of Part 264 Subpart F. However, the large
possibility for non-uniqueness In Interpretation, problems Involved 1n pumping
contaminated fluids, and the expense of conducting such tests generally
J~30 Revision 0
Date September 1985
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WtU. CASINO
k»
I
•il_
I
nrJ
OMAVEU ^ACK
^
ITATIC WATCH
LfVCL
to) CASIO WITM SCftlEN
(bl CASf 0. NO SCMIN. NO
CAVITY KNCAACIMCNT
tet O^EN SOKlMOLf
Figur* 9.—Variable dcfiAitions for slug tests in
unconfin«d materials. Cased wells are
open at the bottom.
J-31
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Date September 1986
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If the compresslve storage 1$ altered by changing the volume of the
packed-off cavity (V), then the combined compressibility of the
water and the expansion of the cavity (Co) 1s used. CQ 1s computed
by measuring the volume of water Injected during pressurlration (AV)
and the pressure change (AP) for the pressurlzatlon:
(Neuzll, p. 440 (1982)). Use of Co requires an accurate method of
metering the volume of water Injected and the volume of the cavity.
3.4.2.4 Sources of error; The types of errors 1n this method
are the same as those for th"e conventional slug test. Errors may
also arise by Inaccurate determination of the cavity volume and
volume of water Injected. An additional assumption that 1s required
for this method 1s that the hydraulic properties of the Interval
tested remain constant throughout the test. This assumption can
best be satisfied by limiting the Initial pressure change to a value
only sufficiently large enough to be measured (Bredehoeft and
Papadopulos, 1980).
3.4.3 Methods for moderately permeable materials under unconflned
conditions:
3.4.3.1 Applicability; This method 1s applicable to wells
that fully or partiallypenetrate the Interval of Interest (Figure
9). The hydraulic conductivity determined will be principally the
value 1n the horizontal direction (Bouwer and R1ce, 1976).
3.4.3.2 Procedures; A general method for testing cased wells
that partly or fully penetrate aquifers that have a water table as
the upper boundary of the zone to be tested was developed by Bouwer
and R1ce (1976). The geometry and dimensions that are required to
be known for the method are shown 1n Figure 9. The test 1s
accomplished by effecting a sudden change 1n fluid potential 1n the
well by withdrawal of either a bailer or submerged float as
discussed 1n Section 3.4.1.2. Water-level changes can be monitored
with either a pressure transducer and recorder, a wetted steel tape,
or an electric water-level sounder. For highly permeable
formations, a rapid-response transducer and recorder system Is
required. The resolution of the transducer should be about 0.01 m.
3.4.3.3 Calculations; The hydraulic conductivity 1s
calculated using the following equation from Bouwer and R1ce (1976),
1n the notation of this report:
rr2 In R/r Yft
* ' C2Let ln F (12)
J"32 Revision
Date September 1986
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VlUt
Pnuuri Gagt
Svsttn* Filled
with Wattr ^
^Citing
Pump
Land Surfae»
Initial Head
•in Tettt
Inttrvtl
;-»»»j H-I-C-I-I-I-
Ttittd :^-
Tiflht
. Formation*
itturt Gagtf/\
•d
Sytttm Filled
with Wjttr
^^pen Holt
"VP»cktr-~V_
"Inttrvjl t&~~—
"bt Ttittd ^-
Pump
(a)
(b)
Figur* 8. —Schematic diagram for pressurized slug
test method in unconsolidated (a) and
consolidated (b) materials. Source:
Papadopulos and Bredehoeft, 1980.
J-33
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Date September 1986
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3.4.2 Methods for extremely tight formations under confined
conditions:
3.4.2.1 Applicability; This test 1s applicable to materials
that have low to extremely low permeability such as silts, clays,
shales, and Indurated Hthologlc units. The test has been used to
determine hydraulic conductivities of shales of as low as 10'10
cm/sec.
3.4.2.2 Procedures; The test described by Bredehoeft and
Papadopulos (1980) and modified by Neuzll (1982) 1s conducted by
suddenly pressurizing a packed-off zone 1n a portion of a borehole
or well. The test 1s conducted using a system such as shown 1n
Figure 8. The system 1s filled with water to a level assumed to be
equal to the prevailing water level. (This step 1s required 1f
sufficiently large times have not elapsed since the drilling of the
well to allow full recovery of water levels.) A pressure transducer
and recorder are used to monitor pressure changes 1n the system for
a period prior to the test to obtain pressure trends preceding the
test. The system Is pressurized by addition of a known volume of
water with a high-pressure pump. The valve 1s shut and the pressure
decay 1s monitored. Neuzll 's modification uses two packers with a
pressure transducer below the bottom packer to measure the pressure
change 1n the cavity and one between the two packers to monitor any
pressure change caused by leakage around the bottom packer.
3.4.2.3 Calculations; The modified slug test as developed by
Bredehoeft and Papadopulos (1980) considered compresslve storage of
water 1n the borehole. These authors considered that the volume of
the packed-off borehole did not change during the test and that all
compresslve storage resulted 1n compression of water under the
pressure pulse. Neuzll (1980) demonstrated that under some test
conditions this 1s not a valid assumption. The computational from
either lohman, Plate 2 (1972) or plotted from data given 1n Appendix
A as described 1n Section 3.4.1.3. The values of time (t) and
dimenslonless time (fl) are determined 1n the same manner as for the
conventional tests. If compression of water only 1s considered,
transm1ss1v1ty 1s computed by replacing rc by the quantity
1n Equation 10:
T • UO,
where:
Vy 1s the volume of water 1n the packed-off cavity, L3;
Cy 1s the compressibility of water, LT^-l;
p 1s the density of water, ML~3; and
g 1s the acceleration of gravity, LT*2.
J-34 Revision p
Date September 1986
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The type curves plotted using data 1n Appendix A are not to be
confused with those commonly referred to as "Thels Curves' which
are used for pumping tests 1n confined aquifers (Lohman, 1972).
The type curve Method 1s a general technique of determining
aquifer parameters when the solution to the descriptive flow
equation Involves more than one unknown parameter. Although
both the storage coefficient and trans«1ss1v1ty of the tested
Interval can be determined with the type curve method for slug
tests, determination of storage coefficients 1s beyond the scope
of this report. See Section 3.4.1.4 for further discussion of
the storage coefficient.
If the data 1n Appendix A are used, a type curve for each
value of a 1s prepared by plotting F(a,4) on the arithmetic
scale and dlmenslonless time (/) on the logarithmic scale of
semi-log paper.
2. Determine the hydraulic conductivity by dividing the
transmlsslvlty (T) calculated above by the thickness of the
tested zone.
3.4.1.4 Sources of error; The errors that can arise 1n
conducting slug tests can beof three types: those resulting from
the well or borehole construction; measurement errors; and data
analysis error.
Well construction and development errors; This method assumes that
the entire thickness of the zoneof Interest 1s open to the well
screen or boreholes and that flow 1s principally radial. If this 1s
not the case, the computed hydraulic conductivity may be too high.
If the well 1s not properly developed, the computed conductivity
will be too low.
Measurement errors; Determining or recording the fluid level 1n the
borehole an3 tKe time of measurement Incorrectly can cause
measurement errors. Water levels should be measured to an accuracy
of at least 1 percent of the Initial water-level change. For
moderately permeable materials, time should be measured with an
accuracy of fractions of minutes, and, for more permeable materials,
the time should be measured In terms of seconds or fractions of
seconds. The latter may require the use of a rapid-response
pressure transducer and recorder system.
Data analysis errors; The type curve procedure requires matching
the data tooneo? a family of type curves, described by the
parameter , which 1s a measure of the storage 1n the well bore and
aquifer. Papadopulos and others (1973) show that an error of two
orders of magnitude 1n the selection of would result 1n an error
of less than 30 percent 1n the value of transmlsslvlty determined.
Assuming no error 1n determining the thickness of the zone tested,
this 1s equivalent to a 30 percent error 1n the hydraulic
conductivity.
J~35 Revision 0
Date September 1986
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3.4.1.2 Procedures; The slug test 1s run by utilizing some
method of removing or Adding a known volume of water from the wen
bore 1n a very short time period and measuring the recovery of the
water level 1n the well. The procedures are the same for both
unconflned and confined aquifers. Water 1s most effectively removed
by using a bailer that has been allowed to fill and stand 1n the
well for a sufficiently long p«r1od of t1»e so that any water-level
disturbance caused by the Insertion of the bailer will have reached
equilibrium. In permeable materials, this recovery time may be as
little as a few minutes. An alternate method of effecting a sudden
change 1n water level 1s the withdrawal of a w«1ghted float. The
volume of water displaced can be computed using the known submersed
volume of the float and Archimedes' principle (Lehman, 1972).
Water-level changes are recorded using either a pressure
transducer and a strip chart recorder, a weighted steel tape, or an
electric water-level probe. For testing permeable materials that
approach or exceed 70 cmvsec, a rapid- response transducer/recorder
system 1s usually used because essentially full recovery may occur
1n a few minutes. Because the rate of water-level response decays
with time, water-level or pressure changes should be taken at
Increments that are approximately equally spaced 1n the logarithm of
the time since fluid withdrawal. The test should be continued until
the water level 1n the well has recovered to at least 85 percent of
the Initial pre-test value.
3.4.1.3 Calculations; Calculations for determining hydraulic
•conductivity Tor moderately permeable formations under confined
conditions can be made using the following procedure:
1. Determine the transm1ss1v1ty of the tested zone by plotting the
ratio h/h0 on an arithmetic scale against time since removal of
water (t) on a logarithmic scale. The observed fluid potential
1n the well during the test as measured by water level or
pressure 1s h, and the fluid potential before the Instant of
fluid withdrawal 1s h0. The data plot 1s superimposed on type
curves, such as those given by Lohman (1972), Plate 2, or
plotted from Appendix A, with the h/h<, and time axes coincident.
The data plot 1s moved horizontally until the data fits one of
the type curves. A value of time on the data plot corresponding
to a d1mens1onless time (f) on the type curve plot 1s chosen,
and the transm1s$1v1ty 1s computed from the following:
T C
T • — r do)
where:
rc 1s the radius of the casing (Lohman, p. 29 (1972)).
J-36 '
Revision p
Date September 1986
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I ,
WELL CASING
CONFINING LAYER Xx /'
WELL SCREEN
'xx
.- CONFINING LAYER /X///
//xxxxT-vxxx^
Figure 7.—Geometry and variable definition for
•lug tests in confined aquifers.
J-37
Revision o
Date September 1986
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pumping can be very similar. Consequently, 1t 1s not considered
acceptable practice to obtain data from a hydraulic conductivity test and
Interpret the type of hydraulic system present without supporting
geologic evidence.
3.3.3 The primary use of hydraulic conductivity data from tests
described subsequently will usually be to aid 1n siting monitoring wells
for facility design as well as for compliance with Subpart F of Part 264.
As such, the methods are abbreviated to provide guidance 1n determining
hydraulic conductivity only. Additional analyses that may be possible
with some methods to define the storage properties of the aquifer are not
Included. The U.S. EPA TEGO has an expanded discussion on the
relationship between K tests and siting design (Chapter 1) and should be
consulted.
3.3.4 The well test methods are discussed under the following two
categories: 1) methods applicable to coarse-grained materials and tight
to extremely tight materials under confined conditions; and 2) methods
applicable to unconflned materials of moderate permeability. The single
well tests Integrate the effects of heterogeneity and anlsotropy. The
effects of boundaries such as streams or less permeable materials usually
are not detectable with these methods because of the small portion of the
geologic unit that 1s tested.
3.4 Single well tests; The tests for determining hydraulic conductivity
with a single well are BTscussed below based on methods for confined and
unconflned conditions. The methods are usually called slug tests because the
test Involves removing a slug of water Instantaneously from a well and
measuring the recovery of water 1n the well. The method was first developed
by Hvorslev (1951), whose analysis did not consider the effect of fluid stored
1n the well. Cooper and others (1967) developed a method that considers well
bore storage. However, their method only applied to wells that are open to
the entire zone to be tested and that tap confined aquifers. Because of the
rapid water-level response 1n coarse materials, the tests are generally
limited to zones with a transm1ss1v1ty of less than about 70 cm^/sec (Lohman,
1972). The method has been extended to allow testing of extremely tight
formations by Bredehoeft and Papadopulos (1980). Bouwer and R1ce (1976)
developed a method for analyzing slug tests for unconflned aquifers.
3.4.1 Method for moderately permeable formations under confined
conditions:
3.4.1.1 Applicability; This method 1s applicable for testing
zones to which the entire zone 1s open to the well screen or open
borehole. The method usually 1s used 1n materials of moderate
hydraulic conductivity which allow measurement of water-level
response over a period of a hour to a few days. More permeable
zones can be tested with rapid response water-level recording
equipment. The method assumes that the tested zone 1s uniform In
all radial directions from the test well. Figure 7 Illustrates the
test geometry for this method.
J-38
Revision 0
Date September 1986
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3.1.3 Wells not requiring well screens: If the zone to be tested
Is sufficiently Indurated that a well screen and casing are not required
to prevent caving 1n, 1t 1s preferable to use a borehole open to the zone
to be tested. These materials generally are those having low to
extremely low hydraulic conductivities. Consolidated rocks having high
conductivity because of the presence of fractures and solution openings
nay also be completed without the use of a screen and gravel pack.
Uncased wells may penetrate several zones for which hydraulic
conductivity tests are to be run. In these cases, the zones of Interest
can be Isolated by the use of Inflatable packers.
3.2 Well development; For wells that are constructed with well screens
and gravel packs, and for all wells 1n which drilling fluids have been used
that nay have penetrated the materials to be tested, adequate developaent of
the well 1s required to remove these fluids and to remove the fine-grained
materials from the zone around the well screen. Development 1s carried out by
methods such as Intermittent pumping, jetting with water, surging, and
balling. Adequate development 1s required to assure maximum communication
between fluids 1n the borehole and the zone to be tested. Results from tests
run 1n wells that are Inadequately developed will Include an error caused by
loss of fluid potential across the undeveloped zone, and computed hydraulic
conductivities will be lower than the actual value. Bouwer (1978) and Johnson
(1975) give further details on well development Including methods to determine
when adequate development has occurred. The U.S. EPA TEGO should also be
consulted.
3.3 Data Interpretation and test selection considerations; Hydraulic
conductivity may be determined 1n wells that are either cased or uncased as
described 1n Section 3.1. The tests all Involve disturbing the existing fluid
potential 1n the tested zone by withdrawal from or Injection of fluid Into a
well, either as a slug over an extremely short period of time, or by
continuous withdrawal or Injection of fluid. The hydraulic conductivity 1s
determined by measuring the response of the water level or pressure 1n the
well as a function of time since the start of the test. Many excellent
references are available that give the derivation and use of the methods that
are outlined below, Including Bouwer (1978), Walton (1969), and Lohman (1972).
3.3.1 The selection of a particular test method and data analysis
technique requires the consideration of the purposes of the test, and the
geologic framework 1n which the test 1s to be run. Knowledge of the
stratlgraphlc relationships of the zone to be tested and both overlying
and underlying materials should always be used to select appropriate test
design and data Interpretation methods.
3.3.2 The equations given for all computational methods given here
and 1n the above references are based on Idealized models comprising
layers of materials of different hydraulic conductivities. The water-
level response caused by disturbing the system by the addition or removal
of water can be similar for quite different systems. For example, the
response of a water-table aquifer and a leaky, confined aquifer to
Revision 0
Date September 1986
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1. Hollow-stem auger;
2. Cable tool;
3. A1r rotary;
4. Rotary drilling with non-organic drilling fluids;
5. A1r foam rotary; and
6. Rotary with organic-based drilling fluids.
Although the hollow stem-auger method 1s usually preferred for the
Installation of most shallow wells (less than 100 feet), care mist be
taken 1f the tested zone 1s very fine. Smearing of the borehole walls by
drilling action can effectively seal off the borehole from the adjacent
formation. Scarification can be used to remedy this.
3.1.2 Wells requiring well screens: Well screens placed opposite
the Interval to be tested should be constructed of materials that are
compatible with the fluids to be encountered. Generally an Inert plastic
such as PVC 1s preferred for ground water contamination studies. The
screen slot size should be determined to minimize the Inflow of fine-
grained material to the well during development and testing. Bouwer
(1978) and Johnson (1972) give a summary of guidelines for sizing well
screens.
3.1.2.1 The annul us between the well screen and the borehole
should be filled with an artificial gravel pack or sand filter.
Guidelines for sizing these materials are given by Johnson (1972).
For very coarse materials, 1t may be acceptable to allow the
materials from the tested zone to collapse around the screen forming
a natural gravel pack.
3.1.2.2 The screened Interval should be Isolated from
overlying and underlying zones by materials of low hydraulic
conductivity. Generally, a short bentonlte plug 1s placed on top of
the material surrounding the screen, and cement grout 1s placed 1n
the borehole to the next higher screened Interval (In the case of
multiple screen wells), or to the land surface for single screen
wells.
3.1.2.3 Although considerations for sampling may dictate
minimum casing and screen diameters, the recommended guideline 1s
that wells to be tested by pumping, balling, or Injection 1n coarse-
grained materials should be at least 4-1nches Inside diameter.
Wells to be used for testing materials of low hydraulic conductivity
by sudden removal or Injection of a known volume of fluid should be
constructed with as small a casing diameter as possible to maximize
measurement resolution of fluid level changes. Casing sizes of 1.25
to 1.50 Inches usually allow this resolution while enabling the
efficient sudden withdrawal of water for these tests.
J-40 '
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Date September 1986
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Investigation. The person responsible for such selections should be a
qualified hydrogeologlst or geotechnlcal engineer who 1s experienced 1n the
application of established principles of contaminant hydrogeology and ground
water hydraulics. The following are given as general guidelines.
1. The bottom of the screened Interval should be below the lowest
expected water level.
2. Wells should be screened 1n the Hthologlc units that have the
highest probability of either receiving contaalnants or
conveying then down gradient.
3. Wells up gradient and down gradient of sites should be screened
1n the sane Hthologlc unit.
Standard reference texts on ground water hydraulics and contaminant
hydrogeology that should be consulted Include: Bear (1972), Bouwer (1978),
Freeze and Cherry (1979), Stallnan (1971), and Walton (1970).
The success of field methods 1n determining hydraulic conductivity 1s
often determined by the design, construction, and development of the well or
borehole used for the tests. Details of these methods are beyond the scope of
this report; however, Important considerations are given 1n Sections 3.1 and
3.2. Detailed discussions of well Installation, construction, and development
methods are given by Bouwer, pp. 160-180 (1978), Acker (1974), and Johnson
(1972).
The methods for field determination of hydraulic conductivity are
restricted to well or piezometer type tests applicable below existing water
tables. Determinations of travel times of leachate and dissolved solutes
above the water table usually require the application of unsaturated flow
theory and methods which are beyond the scope of this report.
3.1 Well-construction considerations; The purpose of using properly
constructed wells for hydraulicconductivity testing 1s to assure that test
results reflect conditions 1n the materials being tested, rather than
conditions caused by well construction. In all cases, diagrams showing all
details of the actual well or borehole constructed for the test should be
made. Chapter 3 of the U.S. EPA, RCRA Ground Water Monitoring Technical
Enforcement Guidance Document (TEGD) should be consulted.
3.1.1 Veil Installation methods: Well Installation methods are
listed below 1n order of preference for ground water testing and
monitoring. The order was determined by the need to minimize side-wall
plugging by drilling fluids and to maximize the accurate detection of
saturated zones. This order should be used as a guide, combined with the
Judgment of an experienced hydrogeologlst In selecting a drilling method.
The combined uses of wells for hydraulic conductivity testing, water-
level monitoring, and water-quality sampling for organic contaminants
were considered 1n arriving at the ranking.
J-41*
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Date September 1986
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conductivity (Anderson and Brown, 1981). This procedure maintains fluid
saturation of the sample, and allows a comparison of the leachate and
hydraulic conductivities under the same test conditions. This procedure
requires modifications of test operations as described below.
2.11.5 Apparatus: In addition to a supply reservoir for water as
shown 1n Figures 3 through 6, a supply reservoir for leachate 1s
required. Changing the Inflow to the test cell.fFOB water to leachate
can be accomplished by providing a three-way valve 1n the Inflow line
that 1s connected to each of the reservoirs.
2.11.6 Measurements: Measureaents of fluid potential and outflow
rates are the same for leachate conductivity and hydraulic conductivity.
If the leachate does not alter the Intrinsic permeability of the sample,
the criteria for the time required to take measurements 1s the same for
leachate conductivity tests as for hydraulic conductivity tests.
However, 1f significant changes occur 1n the sample by the passage of
leachate, measurements should be taken until either the shape of a curve
of conductivity versus pore volume can be defined, or until the leachate
conductivity exceeds the applicable design value for hydraulic
conductivity.
2.11.7 Calculations: If the leachate conductivity approaches a
constant value, Equations (8) and (9) can be used. If the conductivity
changes continuously because of the action of the leachate, the following
modifications should be made. For constant-head tests, the conductivity
should be determined by continuing a plot of outflow volume versus time
for the constant rate part of the test conducted with water. For
falling-head tests, the slope of the logarithm of head versus time should
be continued.
2.11.7.1 If the slope of either curve continues to change
after the flow of leachate begins, the leachate 1s altering the
Intrinsic permeability of the sample. The leachate conductivity 1n
this case 1s not a constant. In this case, values of the slope of
the outflow curve to use 1n Equation (8) or (9) must be taken as the
tangent to the appropriate outflow curve at the times of
measurement.
3.0 FIELD METHODS
This section discusses methods available for the determination of fluid
conductivity under field conditions. As most of these tests will use water as
the testing fluid, either natural formation water or water added to a borehole
or piezometer, the term hydraulic conductivity will be used for tht remainder
of this section. However, 1f field tests are run with leachate or other
fluids, the methods are equally applicable.
The .location of wells, selection of screened Intervals, and the
appropriate tests that are to be conducted depend upon the specific site under
J-42
Revision Q
Date September 1986
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2.11 Leachate conductivity using laboratory methods; Many primary and
secondary leachates foundat disposalsites nayBenonaqueous liquids or
aqueous fluids of high 1on1c strength. These fluids may significantly alter
the Intrinsic permeability of the porous medium. For example, Anderson and
Brown (1981) have demonstrated Increases 1n hydraulic conductivity of
compacted clays of as much as two orders of magnitude after the passage of a
few pore volumes of a wide range of organic liquids. Consequently, the
effects of leachate on these materials should be evaluated by laboratory
testing. The preceding laboratory methods can all be used to determine
leachate conductivity by using the following guidelines.
2.11.1 Applicability: The determination of leachate conductivity
may be required for both fine-grained and coarse-grained materials.
Leachates may either Increase or decrease the hydraulic conductivity.
Increases are of concern for compacted clay liners, and decreases are of
concern for drain materials. The applicability sections of the preceding
methods should be used for selecting an appropriate test for leachate
conductivity. The use of the modified compaction method (Section 2.7)
for determining leachate conductivity 1s discussed extensively 1n EPA
Publication SV870 (EPA 1980).
2.11.2 Leachate used: A supply of leachate must be obtained that
1s as close 1n chemical and physical properties to the anticipated
leachate at the disposal site as possible. Methods for obtaining such
leachate are beyond the scope of this report. However, recent
publications by EPA (1979) and Conway and Malloy (1981) give
methodologies for simulating the leaching environment to obtain such
leachate. Procedures for deal ring the leachate supply are given 1n
Section 2.4. The Importance of preventing bacterial growth In leachate
tests will depend on the expected conditions at the disposal site. The
chemical and physical properties that may result 1n corrosion,
dissolution, or encrustation of laboratory hydraulic conductivity
apparatus should be determined prior to conducting a leachate
conductivity test. Properties of particular Importance are the pH and
the vapor pressure of the leachate. Both extremely addle and basic
leachates may corrode materials. In general, apparatus for leachate
conductivity tests should be constructed of Inert materials, such as
acrylic plastic, nylon, or Teflon. Metal parts that might come 1n
contact with the leachate should be avoided. Leachates with high vapor
pressures may require special treatment. Closed systems for fluid supply
and pressure measurement, such as those 1n the modified trlaxial-cell
methods, should be used.
2.11.3 Safety: Tests Involving the use of leachates should be
conducted under a vented hood, and persons conducting the tests should
wear appropriate protective clothing and eye protection. Standard
laboratory safety procedures such as those as given by Manufacturing
Chemists Association (1971) should be followed.
2.11.4 Procedures: The determination of leachate conductivity
should be conducted Immediately following the determination of hydraulic
J-43
Revision 0
Date September 1986
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TABLE C (Continued)
Grain-Size Class or Range
From Sample Description
Degree of Sorting
Poor Moderate Well
Silt Content
Slight Moderate High
Sands and Gravel$(*)
Very coarse sand
Very coarse sand to fine gravel
Very coarse sand to Medium gravel
Very coarse sand to coarse gravel
Fine gravel
Fine to medium gravel
Fine to coarse gravel
Medium gravel
Medium to coarse gravel
Coarse gravel
107
134
1270
207
160
201
245
241
294
334
147
214
199-227
-
214
334
289-334
231
468
468
187
-
-
-
267
.
-
401
-
602
114
120
147
160
227
201
234
241
294
334
94
104
123
132
140
167
189
201
243
284
74
87
99
104
107
134
144
160
191
234
(1) Reduce by 10 percent 1f grains are subangular.
Source: Lappala (1978).
J-44
Revision 0
Date September 1986
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preclude their use 1n problems of contaminant hydrogeology. The following
references give excellent discussions of the design and Interpretation of
these tests: Lohman (1972), Stallnan (1971), and Walton (1970).
3.6 Estimates of hydraulic conductivity for coarse-grained materials:
The characterization of ground waterfTowsystemsto satisfy the Intent of
Part 264 Subpart F 1s preferably done with flow nets based on borehole
measurements rather than relying on Interpolation from grain-size analyses.
An empirical approach that has been used by the U.S. Geological Survey
(Lappala, 1978) 1n several studies relates conductivity determined by aquifer
testing to grain-size, degree of sorting and silt content. Table C provides
the estimates of hydraulic conductivity.
Although estimates of K from analysis of grain-size and degree of sorting
do provide a rough check on test values of K, repeated slug tests provide a
better check on the accuracy of results.
3.7 Consolidation tests; As originally defined by Terzagl (Terzaghl and
Peck, 1967}th"ecoefficient of consolidation (Cv) of a saturated,
compressible, porous medium 1s related to the hydraulic conductivity by:
C • —— (15)
• PQfi »*•*/
where:
K Is the hydraulic conductivity, LT~;
f 1s the fluid density, ML'3;
g 1s the gravitational constant, IT'2; and
a 1s the soil's compressibility,
The compressibility can be determined 1n the laboratory with several types of
consolldometers, and 1s a function of the applied stress and the previous
loading history. Lambe (1951) describes the testing procedure.
3.7.1 The transfer value of results from this testing procedure 1s
Influenced by the extent to which the laboratory loading simulates field
conditions and by the consolidation rate. The laboratory loadings will
probably be less than the stress that remolded clay Uner will
experience; therefore, the use of an already remolded sample 1n the
consolldometer will probably produce no measurable results. This
suggests that the test 1$ of little utility 1n determining the hydraulic
conductivity of remolded or compacted, fine-grained soils. Second, the
consolidation rate determines the length of the testing period. For
granular soils, this rate 1s fairly rapid. For fine-grained soils, the
rate may be sufficiently slow that the previously described methods,
J"45 Revision 0
Date September 1986
-------
which give faster results, will be preferable. Cohesive soils (clays)
must be trimmed from undisturbed samples to fit the mold, while
cohesion! ess sands can be tested using disturbed, repacked samples
(Freeze and Cherry, 1979).
3.7.2 In general, EPA believes that consolidation tests can provide
useful Information for some situations, but prefers the previously
described methods because they are direct measurements of hydraulic
conductivity. Hydraulic conductivity values determined using
consolidation tests are not to be used 1n permit applications.
3.8 Fractured media; Determining the hydraulic properties of fractured
media 1s always a difficult process. Unlike the case with porous media,
Darcy's Law 1s not strictly applicable to flow through fractures, although 1t
often can be applied empirically to large bodies of fractured rock that
Incorporate many fractures. Describing local flow conditions 1n fractured
rock often poses considerable difficulty. Sowers (1981) discusses
determinations of hydraulic conductivity of rock. This reference should be
consulted for guidance 1n analyzing flow through fractured media.
3.8.1 Fine-grained sediments, such as glacial tills, are commonly
fractured 1n both saturated and unsaturated settings. These fractures
may be sufficiently Interconnected to have a significant Influence on
ground water flow, or they may be of very limited connection and be of
little practical significance.
3.8.2 Frequently, a laboratory test of a small sample of clay will
determine hydraulic conductivity to be on the order of 10"* on/sec. A
piezometer test of the same geologic unit over an Interval containing
fractures may determine a hydraulic conductivity on the order of perhaps
10-5 or 10-6 cm/sec. To assess the extent of fracture Interconnection,
and hence the overall hydraulic conductivity of the unit, several
procedures can be used. Closely spaced piezometers can be Installed; one
can be used as an observation well while water 1s added to or withdrawn
from the other. Alternately, a tracer might be added to one piezometer,
and the second could be monitored. These and other techniques are
discussed by Sowers (1981).
3.8.3 For situations that may Involve flow through fractured media,
1t Is Important to note 1n permit applications that an apparent hydraulic
conductivity determined by tests on wells that Intersect a small number
of fractures may be several orders others of magnitude lower or higher
than the value required to describe flow through parts of the ground
water system that Involve different fractures and different stress
conditions from those used during the test.
4.0 CONCLUSION
4.1 By following laboratory and field methods discussed or referenced 1n
this report, the user should be able to determine the fluid conductivity of
materials used for liners, caps, and drains at waste-disposal facilities, as
J-46
Revision 0
Date September 1986
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well as materials composing the local ground water flow system. If fluid-
conductivity tests are conducted and Interpreted properly, the results
obtained should provide the level of Information necessary to satisfy
applicable requirements under Part 264.
5.0 REFERENCES
1. Acker, W. L., Ill, Basic Procedures for Soil Sampling and Core Drilling,
Acker Drill Co., 246 p., 1974.
2. Allison, I.E., Effect of Microorganisms on Permeability of Soil under
Prolonged Submergence, Soil Science, 63, pp. 439-450 (1947).
3. American Society for Testing and Materials (ASTM), Annual Book of ASTM
Standards, Part 19, 1978.
4. Anderson, 0., and K. W. Brown, Organic Leachate Effects on the
Permeability of Clay Liners, 1n Proceedings of Solid Waste Symposium, U.S.
EPA, p. 119-130, 1981.
5. Bear, J., Dynamics of Fluids 1n Porous Media, American Elsevler, 764 p.,
1972.
6. Bouwer, H., and R. C. Rice, A Slug Test for Determining Hydraulic
Conductivity of Unconflned Aquifers with Completely or Partially Penetrating
Wells, Water Resources Research, 12, p. 423-428 (1976).
7. Bredehoeft, J. D., and S. S. Papadopulos, A Method for Determining the
Hydraulic Properties of Tight Formations, Water Resources Research, 1£, p.233-
238 (1980).
8. Conway, R. A., and B. C. Malloy, eds., Hazardous Solid Waste Testing:
First conference, ASTM Special Technical Publication 760, 1981.
9. Cooper, H. H., J. D. Bredehoeft, and I. S. Papadopulos, Response of a
Finite Diameter Well to an Instantaneous Charge of Water, Water Resources
Research, 3, p. 263-269 (1967).
10. Dakesslan, S., et al., Lining of Waste Impoundment and Disposal
Facilities, Municipal Environment Research Laboratory, U.S. EPA, Cincinnati.
OH, EPA-530/SW-870C, pp. 264-269, 1980.
11. Fireman, M., Permeability Measurements on Disturbed Soil Samples, Soil
Science, 58, pp. 337-355 (1944).
12. Freeze, R. A., and J. A. Cherry, Ground Water, Prentice Hall, 604 p.,
1979.
7
J~47 Revision
Date September 1986
-------
13. Gordon, B.B., and M. Forrest, Permeability of Soil Using Contaminated
Permeant, 1n Permeability and Ground Water Contaminant Transport, ed. T. F.
Z1nro1e and~C. 0. R1ggs, ASTM Special Technical Publication 746, p. 101-120,
1981.
14. Hlllel, 0., Soil and Water, Academic Press, 288 p., 1971.
15. Hvorslev, M. J., T1«e Lag and Soil Permeability 1n Ground Water
Observations, U.S. Army Corps of Engineers Waterways Experiment Station Bull.
36, 1951.
16. Johnson, A. I., Symposium on Soil Permeability, ASTM STP 163, American
Society of Testing and Materials, Philadelphia, pp. 98-114, 1954.
17. Johnson, E. E., Inc., Ground Water and Wells, Johnson Division, UOP,
440 p., 1975.
18. Lappala, E. 6., Quantitative Hydrogeology of the Upper Republican Natural
Resources District, Southwest Nebraska, U.S. Geological Survey Water Resources
Investigations 78-38.
19. Lambe, T. W., Soil Testing for Engineers, John Wiley, N.Y., 1951.
20. Lohman, S. W., Ground Water Hydraulics, U.S. Geological Survey
Professional Paper 708, 70 p., 1972.
21. Lohman, S. W., et al., Definitions of Selected Ground Water Terms -
Revisions and Conceptual Refinements, U.S. Geological Survey Water Supply
Paper 1988, 1972.
22. Manufacturing Chemists Association, Guide for Safety 1n the Chemical
Laboratory, Van Nostrand, Relnhold Co, N.Y., 1971.
23. Mitchell, A.K., and J. S. Younger, Permeability and Capillarity of Soils,
ASTM STP 417, American Society for Testing and Materials, Philadelphia,
pp.106-139, 1967.
24. Neuzll, C. E., On Conducting the Modified 'Slug' Test 1n Tight
Formations, Water Resources Research, 18(2). pp. 439-441 (1982).
25. Olsen, R. E., and D. E. Daniel, Measurement of the Hydraulic Conductivity
of Fine-Grained Soils, 1n Permeability and Ground Water Transport, ed. T.F.
Z1mm1e and C. 0. R1ggs,~7fcTM Special Publication 746, p. 18-64, 1981.
26. Papadopulos, S. S., J. D. Bredehoeft, and H. H. Cooper, Jr., On the
Analysis of 'Slug Test1 Data, Water Resources Research, 9, p. 1087-1089
(1973).
27. Schwartzendruber, D., The Applicability of Darcy's Law, Soil Science
Society of America Proceedings. 32(1). pp. 11-18 (1968).
J-48
Revision 0
Date September 1986
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28. Sowers, 6. F., Rock Permeability or Hydraulic Conductivity — An
Overview, 1n Permeability and Ground Water Transport, ed. T. F- 21nn>1e and Co.
0. R1ggs, A3TM Special Technical Publication 746, 1981.
29. Stall nan, R. W., Aquifer-Test Design, Observation and Data Analysis,
TWRI, Chap. Bl, Book 3, U.S. Geological Survey, U.S. Govt. Printing Office,
Washington, D.C., 1971.
30. Terzaghl, K., and R. B. Peck, Soil Mechanics 1n Engineering Practice, 2nd
ed., John Wiley & Sons, N.Y., 729 p., 1967.
31. Walton, W. C., Ground Water Resource Evaluation, McGraw H111, 664 p.,
1970.
32. Wilkinson, W. B., In S1tu Investigation 1n Soils and Rocks, British and
Geotechnlcal Society, Institution of C1v1l Engineers, London, pp. 311-313,
1969.
33. U.S. Army Corps of Engineers, Laboratory Soil Testing, Waterways
Experiment Station, Vlcksburg, Mississippi, Publication EM 1110-2-2-1906,
1970.
34. U.S. Environmental Protection Agency, Hazardous Waste Guidelines and
Regulations (proposed), Federal Register, Part IV, Dec. 18, 1978.
35. U.S. Environmental Protection Agency, RCRA Ground Water Monitoring
Technical Enforcement Guidance Document, Draft Final.
J-49
Revision
Date Seotemoer 1986
-------
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J-53
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J-55
Revision 0
Date September 1986
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J-56
Revision 0
Date Septemoer 1986
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