From June 1999 through October
2001, GSE in conjunction with industry design and academic professionals
developed the industry’s first GCL design guidance document, the GSE
GundSeal Design Manual. This comprehensive 370 page design manual features
design methodologies and procedures for utilizing the GSE GundSeal
geomembrane supported GCLs in a wide range of composite liner (geomembrane-clay)
applications. It presents state-of-the-practice design principles related to
hydraulic performance evaluation, slope stability analysis, construction
issues, and durability issues in utilizing GSE GundSeal and GCLs in bottom
liner systems, caps, ponds, and secondary containment lining applications.
The design methodologies developed and data presented are based on the input
and expertise of industry professionals, including Richard Thiel (Thiel
Engineering), David Daniel (University of Illinois at Urbana), Richard
Erickson (GSE Lining Technology), Ed Kavazanjian (GeoSyntec Consultants) and
J.P. Giroud (J.P. Giroud, Inc.). GSE would like to acknowledge the
co-authors for their support and creativity in preparing this
state-of-the-practice design guidance document.
A general overview of the manual is presented below with implications in
making a design utilizing GSE GundSeal and GCLs simpler, quicker, and more
effective.
Manual Overview
The GSE GundSeal Design Manual
is organized into three parts, (1) General Principles, (2) Applications, and
(3) Appendices.
Part I: General Principles presents the general applications of GSE GundSeal,
which include use as a one product composite liner or, alternatively, in an
encapsulated mode (geomembrane/bentonite/geomembrane) for improved hydraulic
and slope performance. This is followed by a compilation and analysis of
over 12 years of research and GCL performance data related to hydraulic
performance and slope stability of GCLs and, specifically, the GSE GundSeal
GCL.
Part II: Applications chapters present an overview of current installation,
durability, and construction quality assurance (CQA) issues followed by
specific applications design. Applications include the use of composite
liners and GSE GundSeal in (1) bottom liners, (2) caps, (3) ponds, and (4)
secondary containment applications. Each design chapter initially presents
an overview of composite liner systems, general regulations, and procedures
for performing an equivalency demonstration between compacted clay vs. GCL
composite liner systems. This is followed by a GSE GundSeal design
‘check-list’ summarizing relevant design considerations with corresponding
cross-references within the manual.
For example, related to bottom liner systems, the design check-list (Design
Manual Table 5.1) presents the following design criteria with manual section
references:
Table 5.1 GSE GundSeal Design
Considerations for Bottom Liners.
Category
Criterion for Evaluation
HYDRAULIC ISSUES
Hydraulic conductivity
(Sec. 2.2.3)
Leakage rates through
defects in geomembranes (Sec.2.3)
Leakage through overlapped
seams (Sec. 2.4)
Leakage through
encapsulated GundSeal (Sec. 2.5)
Chemical attenuation,
absorption, & diffusion (Sec. 2.7.1)
Construction quality control (CQC)
& quality assurance (CQA) (Sec. 4.6)
The application check-lists are
followed by step-by-step procedures for evaluating composite liner
performance related to hydraulic performance (e.g., leakage). The hydraulic
evaluation presents sample design calculations for GSE GundSeal composite
lining systems along with corresponding leakage through a conventional
prescriptive geomembrane/compacted clay composite lining systems.
The next section in each design chapter focuses on slope stability.
State-of-the-practice slope stability analyses and design methodologies for
veneer and bottom liner systems are presented with example calculations and
evaluation for typical GCL composite liner applications. Both static and
seismic stability analyses are based on an extensive direct shear test
program and historical test data defining the shear strength properties of
the dry and hydrated bentonite component of GSE GundSeal.
Each design chapter also includes a discussion of all related durability
issues and construction issues for each application and presents criteria
related to effective construction quality assurance (CQA).
Part III: The appendices section of the manual includes a total of 11
Appendices as support documentation to the principles and design sections of
the manual. Highlights include (a) hydraulic analysis of bentonite hydration
between geomembranes and at overlapped seams (for future publication, Giroud
et al.), (b) example PCSTABL5 computer software slope stability analysis,
(c) generic landfill seismic stability analysis, (d) direct shear testing
program establishing the shear strength properties of bentonite and GSE
GundSeal, (e) electrical defect detection survey of composite liner systems,
(f) sample composite liner HELP Model leakage analysis, and (g) sample GSE
GundSeal drop-in project specifications with relevant CQA issues and
procedures.
Summary
The state-of-the-practice design methodologies
developed and data presented in the GSE GundSeal Design Manual are based on
the input and expertise of industry design and academic professionals,
including Richard Thiel (Thiel Engineering), David Daniel (University of
Illinois at Urbana), Richard Erickson (GSE Lining Technology), Ed
Kavazanjian (GeoSyntec Consultants), and J.P. Giroud (J.P. Giroud, Inc.).
GSE and the co-authors hope the manual will become an easy to use guide in
designing and constructing more effective and cost efficient composite
lining systems that incorporate GSE GundSeal and GCLs.
Landfill bottom liner System with Overlapped GSE GundSeal Composite Liner
GSE and other marks used herein are trademarks and
service marks of GSE Lining Technology, Inc., certain of which are registered
in the U.S.A. and other countries.
