Dedicated to advancing the use of fabricated geomembranes through education, research, and technology transfer.

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Factory fabrication reduces field welding, reduces installation time and costs, allows modular construction and provides consistent seam and liner quality.

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Clarifying the Nomenclature of Elvaloy-Based Geomembranes: EIA, EIP or KEEClarifying the Nomenclature of Elvaloy-Based Geomembranes: EIA, EIP or KEE
E. Silva and T. D. Stark
Geosynthetics Magazine
Since the first flexible membrane liner (FML) was used as part of an environmental liner system, the geomembrane industry has always looked for innovative solutions for chemical containment applications. Although there have been many innovations over the last 50 years, one of the most significant is the introduction of ketone ethylene ester (KEE), which is a solid plasticizer. KEE is available under the Elvaloy trade or product name and is used to plasticize polyvinyl chloride (PVC) geomembranes, as discussed in detail in this article.
FGI expands Summer Internship ProgramFGI expands Summer Internship Program
Timothy D. Stark, University of Illinois at Urbana-Champaign, Jennifer Miller, University of Illinois at Urbana-Champaign, Billy Hernawan, University of Illinois at Urbana-Champaign, Raymond Pu, University of Illinois at Urbana-Champaign, & Abdou Diouff, University of Illinois at Urbana-Champaign
Geosyntheticsmagazine.com November, 2017
The Fabricated Geomembrane Institute (FGI) at the University of Illinois at Urbana-Champaign (UIUC) expanded its student internship program to three companies and six interns during the summer of 2017. The first year of the internship program in 2016, one intern worked for Colorado Lining International (CLI) at various sites in the United States. The main objectives of the program are to introduce future civil engineers to the field of geosynthetics field, civil engineering construction, and provide a connection between possible future employers and the many undergraduate (~2,400) and graduate students (~1,200) at the UIUC.
APPLICATIONS OF GEOSYNTHETICS TO IRRIGATION, DRAINAGE AND AGRICULTUREAPPLICATIONS OF GEOSYNTHETICS TO IRRIGATION, DRAINAGE AND AGRICULTURE
E. BLOND, S. BOYLE, M. FERRARA, B HERLIN, H. PLUSQUELLEC, P. RIMOLDI* and T.D STARK, Ph. D, P.E
23rd International Congress of the ICID in Mexico City
The authors gave an overview of how geosynthetic products are designed and tested to ensure they will fulfil their intended function, focusing on applications to irrigation, drainage and agriculture. A few key considerations were identified as being critical to ensure proper performance of geosynthetic materials, in geotechnical projects in general and in agriculture in particular. The
Protecting Geomembranes from Animal DamageProtecting Geomembranes from Animal Damage
Timothy Stark, University of Illnois, Andrew Mills, Layfield
Geosynthetics Magazine, June/July 2017
Resisting animal and insect attacks of geomembranes is an interesting problem. Geomembrane installers and manufacturers have had numerous geomembranes damaged by bears, deer, coyotes, birds, beavers and ground squirrels. In most cases, the damage is incidental to something else the animal is seeking. Deer damage the liner with their hooves trying to climb out. Bears dig through the liner to try and find something on the other side (organic matter left under a liner in a retrofit). Coyotes burrow under the liner on the slope to create a den that doesn’t freeze.
Soil/Geosynthetic Interface Strengths from Torsional Ring Shear TestsSoil/Geosynthetic Interface Strengths from Torsional Ring Shear Tests
T.D. Stark and R.F. Santoyo
Geotechnical Frontiers 2017 GSP 280
Torsional ring shear tests were conducted to investigate Soil/Geosynthetic Interface Strengths of various geomembranes. The effect of texturing and material properties on shear strength and soil interaction are presented in this paper and compared with existing interface strength values.
Morro Reservoir Rehabilitation ProjectMorro Reservoir Rehabilitation Project
Timothy D. Stark, Ph.D., P.E., D.GE, F.ASCE; Douglas Hilts, S.E. & Jennifer Miller, M.S.
Land and Water, January/February 2017
The Fabricated Geomembrane Institute (FGI) at the University of Illinois at Urbana-Champaign, presented its inaugural Fabricated Geomembrane Engineering Innovation Award to Hilts Consulting Group of Yorba Linda, California, on 11 May, 2016 during its annual membership meeting in Miami Beach, Florida during Geo-Americas 2016. The Fabricated Geomembrane Engineering Innovation Award provides recognition for engineers who have creatively used fabricated geomembranes to successfully fulfill a client’s need including technical requirements, scheduling, and budget. Hilts Consulting Group was selected as the recipient for the award based on their Morro Reservoir Project in Fallbrook, California.
FGI Initiates Summer Internship ProgramFGI Initiates Summer Internship Program
Jennifer Millers, M.S., and Timothy D. Stark, PhD.
geosyntheticsmagazine.com
The Fabricated Geomembrane Institute (FGI), based at the University of Illinois at Urbana-Champaign (UIUC) has concluded its first student internship program. The main objectives of the program are to introduce future civil engineers to the field on geosynthetics and to provide a connection between possible employers and the many undergraduate and graduate students at the UIUC.
Minnesota Geomembrane Durability Study Minnesota Geomembrane Durability Study
T.D. Stark, Ph. D, P.E
Geosynthetis Magazine August 2016
The founders of the Fabricated Geomembrane Institute determined to test materials in field use and partnered with the Minnesota Department of Natural Resources. This project is investigating 30 year durability of PVC geomembrane at a reclamation site near Hibbing, MN.
Tight Timeline + Extreme Specs = A Notable RPE Geomembrane InstallTight Timeline + Extreme Specs = A Notable RPE Geomembrane Install
Bruce Wright
Geosynthetics October/November 2015
Northeastern British Columbia could, by most definitions, be considered the middle of nowhere. Tumbler Ridge (pop. 2,710), a district municipality in the foothills of the Canadian Rockies bordering Alberta, is and was from its inception in 1981 all about coal. And like many a town with a single major industry, it waxes and wanes on the strength of that industry.
Strength Envelopes from Single and Multi Geosynthetic Interface TestsStrength Envelopes from Single and Multi Geosynthetic Interface Tests
T.D Stark, F.S. Niazi and T.C. Keuscher
Geotech Geol Eng (2015)
This paper presents a comparison of single- and multi-interface strength tests for a proposed landfill liner system configuration. The test results are also used to illustrate the effect of different soil types and GCL hydration on the peak and large displacement strength envelopes.
Avoiding Surprises in Slope StabilityAvoiding Surprises in Slope Stability
Timothy D. Stark, Ph.D., P.E., D.GE, F.ASCE, Brian H. Queen, and Hangseok Choi, Ph.D., P.E.
Geo-Strata / www.asce.org/geo
The ability to analyze and compute factors of safety for slopes has increased greatly in the last decade. This ability has increased to the point that factors of safety can be computed using even complex limit equilibrium methods, such as Morgenstern and Price (1960), which used to be too computationally intensive for microcomputers; the finite-difference method, such as FLAC/Slope; and the finite-element method, such as PLAXIS.
Geosynthetics in New Transportation ApplicationsGeosynthetics in New Transportation Applications
Timothy D. Stark and Davik Paiko
Geosynthetics April/May 2014
Geosynthetics are useful and versatile materials that have found a range of applications in transportation projects (Berg and Suits, 2000). Geosynthetic materials can decrease project costs and project time; increase design life, stability, and range of acceptable borrrow material; and improve performance - important given the large backlog of infrasturcture projects and limited funding.
Sustainable geomembrane recycling and downcyclingSustainable geomembrane recycling and downcycling
Timothy D. Stark, Jennifer Miller, David LaFiura, and Scott Fought
Geosynthetics June July 2013
Pennsylvania’s Department of Environmental Protection (DEP) and Department of Community and Economic Development (DCED) officials have welcomed the recent emersion of companies that collect and reprocess geomembranes used in various aspects of Marcellus Shale oil and gas drilling, development, and production. The geomembrane uses include well pad liners, above ground impoundments, secondary containment, and floating covers. Well pad liners are placed over a large area (usually 200ft × 200ft) around the drill well to contain drilling fluids, provide an antislip surface for drill workers, and contain oil and gas products.
Rehabilitation of Raw Water Reservoir for Franklin WTPRehabilitation of Raw Water Reservoir for Franklin WTP
Bill Shehane, P.E.
Land and Water
During the summer of 2007, the city of Franklin, Tennessee and its surroundings were experiencing a severe drought. Due to the high heat and low flows in the Harpeth River, Franklin struggled to meet water supply demands in the area. The city’s raw water reservoir, which can hold 85 million gallons, was completely dry for several months. As a result, the 2.0 MGD Franklin water treatment plant was inoperable for periods of time. Water is normally pumped from the Harpeth River into the raw water reservoir, where it is later treated before consumption.
Air-channel testing of thermally bonded flexible polypropylene geomembrane seamsAir-channel testing of thermally bonded flexible polypropylene geomembrane seams
Timothy 0. Stark, Richard W. Thomas, and Thomas J. Dehlin
Geosynthetics April/May 2013
For more than a decade, thermal welding has proven to be an efficient and costeffective procedure for field-seaming geomembranes. Thermal welding of polyvinyl chloride (PVC) geomembranes has allowed use of air-channel tests in lieu of destructive peel tests to verify field seams meet specified seam peel strength (Thomas and Stark, 2003).
COMPARISON OF SINGLE AND MULTI GEOSYNTHETIC AND SOIL INTERFACE TESTSCOMPARISON OF SINGLE AND MULTI GEOSYNTHETIC AND SOIL INTERFACE TESTS
F. Niazi, K. Keuscher, T.D Stark, Ph. D, P.E
ASTM Geotechnical Testing Journal
This paper presents a comparison of single- and multi-interface strength tests for two possible landfill liner system configurations.
Benefits and Cost Advantages of Fabricated GeomembranesBenefits and Cost Advantages of Fabricated Geomembranes
Timothy D. Stark, Gary Kolbasuk, Stanford Slifer, Duff Simbeck, and Jeremiah Boorsma
Land and Water July/August 2011
Some geomembranes are flexible enough that they can be factory seamed into large panels, folded, transported, unfolded without creasing or damage, and field seamed and tested as necessary. These geomembranes are relatively thin, flexible, and are mainly produced by calendaring, lamination, and extrusion manufacturing processes. In short, calendaring uses a series of hard pressure rollers to form a thin sheet of plastic material, e.g., a geomembrane. Lamination involves constructing a geomembrane by uniting two or more layers of material, e.g., two plastic sheets with a fabric or scrim in the middle. Extrusion manufacturing is a process used to create a thin plastic sheet by forcing heated plastic through a die of the desired thickness.
High-temperature air channel testing of thermally bonded PVC geomembrane seamsHigh-temperature air channel testing of thermally bonded PVC geomembrane seams
T. D. Stark and L. F. Pazmino
Geosynthetics International 2011, 18 No. 2
The objective of this paper is to present a procedure for high sheet temperature air channel testing of dual-track thermal seams for 0.75 mm thick polyvinyl chloride (PVC) geomembranes. The proposed relationship and equation allow the seam peel strength to be verified by field air channel testing without conducting destructive tests.
Underground Stormwater Detention SystemsUnderground Stormwater Detention Systems
Terence Sheridan and Timothy D. Stark
Land and Water May/June 2010
Roosevelt Manor sits in the heart of Camden, New Jersey’s Centerville neighborhood across the Delaware River from Philadelphia. Built in the early 1950’s via authorization of President Harry Truman and under the direction of the Camden Housing Authority, Roosevelt Manor broke new ground as an integrated public housing development. Unfortunately, Camden, like many other urban cities, struggled over the last half of the century. Just over 50 years after opening its doors the four acre development was demolished and with HopeVI funding from the U.S. Department of Housing and Urban Development, Roosevelt Manor was rebuilt.
Design questions and answers for geomembranesDesign questions and answers for geomembranes
T.D. Stark, Ph. D, P.E
Geosynthetics June July 2009
This paper provides answers to design questions for geomembrane including design strength, maximum slope angle ad strength parameters.
Ten-year PVC geomembrane DurabilityTen-year PVC geomembrane Durability
E. J. Newman and T. D. Stark
Geosynthetics International, 2009, 16, No. 2
The 10-year results of an ongoing study on the long-term performance of a PVC geomembrane in Northern Minnesota are presented.
Puncture Resistance of PVC Geomembranes using the truncated cone testPuncture Resistance of PVC Geomembranes using the truncated cone test
T.D Stark, Ph.D, P.E. , T.R. Boerman and C.J Connor
Geosynthetic International 2008, 15 No. 6
This paper presents an experimental study to develop a design procedure for the puncture behavior of PVC geomembranes. After comparison, it was concluded that PVC geomembranes have higher puncture resistance than polyethylene geomembranes despite the PVC membranes being thinner.
Puncture Protection of PVC Geomembranes Puncture Protection of PVC Geomembranes
T.D Stark, Ph. D, P.E and L.F Pazmino
Geosynthetics International, 16
This paper presents a design procedure for the puncture protection of PVC geomembranes. Additionally, a new modification factor for critical cone height, MFCCH, was developed to reflect the puncture resistance of flexible PVC geomembranes.
Massive Mining Evaporation Ponds Constructed in Chilean DesertMassive Mining Evaporation Ponds Constructed in Chilean Desert
Dominic Berube, Patrick Diebel, Andre Rollin, and Timothy D. Stark
Geosynthetics Magazine
The Salar de Atacama in Chile is the site of the largest PVC geomembrane installation in the world - more than 16 million sf. utilized in mining operations since 1996.
Saving Prospect Lake Saving Prospect Lake
Geosynthetics Magazine Volume 24, No. 1
The use of PVC geomembrane facilitates the saving of Prospect Lake since problematic lakebed soils did not have to be disturbed to accommodate the liner. This is the largest US PVC geomembrane installation to date and is a great example of a PVC geomembrane success.
Air-channel testing landfill geomembrane seamsAir-channel testing landfill geomembrane seams
T.D. Stark, Ph.D, P.E, J. Heap, S. Lange, D. McLaury, S. Slifer
GRF March 2005 volume 23 number 2
An extreme test Year 10 An extreme test Year 10
F. Konvalinka
GFR 2005 Volume 23, Number 8
10 years ago, the founders of the PVC geomembrane institute were determined to test materials in field use. They partnered with the Minnesota Department of Natural Resources
Influence of plasticizer molecular weight on plasticizer retention in PVC geomembranesInfluence of plasticizer molecular weight on plasticizer retention in PVC geomembranes
T. D. Stark, H. Choi and P. W. Diebel
Plasticizers can migrate from PVC geomembranes over time because of contact with air, liquid, and/or an absorbent solid material. Plasticizer migration can reduce the flexibility of PVC geomembranes, resulting in brittle behavior. This paper discusses the three mechanisms of plasticizer migration and the factors influencing these mechanisms, such as plasticizer molecular weight and linearity of the plasticizer.
PERFORMANCE OF 30 MIL PVC GEOMEMBRANE EXPOSED TO SYNTHETIC MSW LEACHATEPERFORMANCE OF 30 MIL PVC GEOMEMBRANE EXPOSED TO SYNTHETIC MSW LEACHATE
T.D. Stark, Ph. D, P.E, H. Choi and P.W Diebel
57TH CANADIAN GEOTECHNICAL CONFERENCE
This paper describes laboratory test results that evaluate the chemical compatibility of a 0.76 mm (30 mil) thick flexible PVC geomembrane exposed to a synthetic municipal solid waste (MSW) leachate using ASTM D 5322. It is concluded that this PVC geomembrane is not adversely affected by the synthetic MSW leachate.
PLASTICIZER MOLECULAR WEIGHT AND PLASTICIZER RETENTION IN PVC GEOMEMBRANESPLASTICIZER MOLECULAR WEIGHT AND PLASTICIZER RETENTION IN PVC GEOMEMBRANES
T. D. Stark, Ph. D, P.E, H. Choi and P.W Diebel
57TH CANADIAN GEOTECHNICAL CONFERENCE
This paper discusses the three mechanisms of plasticizer migration and the factors influencing these mechanisms, such as plasticizer molecular weight and linearity of plasticizers. The paper recommends that a minimum average plasticizer molecular weight of 400 be used to ensure long-term plasticizer retention in the field.
Methane gas migration through geomembranesMethane gas migration through geomembranes
T. D. Stark, Ph. D., P.E and H. Choi
Geosynthetics International
This technical note reviews gas transport mechanisms through flexible geomembranes by measuring methane gas transmission rates, permeance and permeability coefficient of PVC, LLDPE and HDPE geomembranes. A field design chart for estimating methane gas transmission rates for different geomembrane thickness and material is shown that can be used by landfill designers.
State-of-the-art report: GCL shear strength and its measurementState-of-the-art report: GCL shear strength and its measurement
P. J. Fox and T. D. Stark
Geosynthetics International, 2004 11 No. 3
This paper provides information on shear strength and shear strength testing of geosynthetic clay liners. Additionally, the paper provides recommendations for the selection of design failure envelopes and information on GCL shear testing programs as well as improvements and future research needs.
Low-temperature air channel testing of thermally bonded PVC geomembrane seamsLow-temperature air channel testing of thermally bonded PVC geomembrane seams
T. D. Stark, H. Choi and R. W. Thomas
Geosynthetics International, 2004, 11, No. 6
The objective of this paper is to develop a procedure for air channel testing of dualtrack thermal seams at low sheet temperatures and recommendations for reducing destructive testing of field PVC geomembrane seams. Thus the proposed relationship and equation allow the seam peel strength to be determined from the field air channel testing without conducting destructive tests.
Occurrence and effect of bentonite migration in geosynthetic clay linersOccurrence and effect of bentonite migration in geosynthetic clay liners
T. D. Stark Ph. D, P.E., H. Choi and R. Akhtarshad
Geosynthetics International 2004 11, No. 4
Since the introduction of geosynthetic clay liners (GCLs) to waste containment facilities, one of the major concerns about their use has been the hydraulic equivalence to a compacted clay liner as required by regulations. This paper presents field case histories that confirm the laboratory observations of bentonite migration and the effect of bentonite migration on hydraulic equivalence and contaminant transport through a GCL
Reduction of destructive tests for PVC seamsReduction of destructive tests for PVC seams
Richard W. Thomas and Timothy D. Stark
GFR, March 2003
One of the current research topics being pursued by the PYC Geomembrane Institute (PGI) is the thermal welding and subsequent air channel testing of PYC geomembrane seams, which is the focus of this article. Other active research projects include the long-term performance ofPYC geomembranes using field case histories, shear behavior of PYC geomembrane interfaces, puncture characteristics of PYC geomembranes, and the chemical resistance ofPYC geomembranes. These projects will be discussed in future articles.
Laboratory Measurement of GLC Shear Strength Laboratory Measurement of GLC Shear Strength
P.J. Fox, T.D Stark and R.H Swan
This paper is about laboratory measurement of internal and interface shear strengths of geosynthetic clay liners. Test apparatus, gripping/clamping, hydration, consolidation, shear displacement and post-test measurement are also addressed.
MUNICIPAL SOLID WASTE SLOPE FAILURE. I: WASTE AND FOUNDATION SOIL PROPERTIESMUNICIPAL SOLID WASTE SLOPE FAILURE. I: WASTE AND FOUNDATION SOIL PROPERTIES
H. T. Eid, T. D. Stark, W. D. Evans, and P. E. Sherry
JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING / MAY 2000
This paper describes a slope failure in a municipal solid waste landfill, with lateral and vertical displacements of up to 275 and 61 m, respectively. To facilitate the analyses, this paper investigates shear strength of municipal solid waste using field and laboratory test results and back-analysis of failed waste slopes.
Flexible geomembrane interface strengthsFlexible geomembrane interface strengths
T.D. Stark Ph. D, P.E and G.N Richardson, Ph. D, P.E
Geotechnical Fabrics Report April 2000
This article briefly describes the shear behavior of flexible geomembrane/nonwoven geotextile interfaces. In addition, a database of PVC, HOPE and VFPE geomembrane/ nonwoven geotextile interface strengths is presented that can be used for comparison purposes.
Shear Behavior of an Unreinforced Geosynthetic Clay Liner Shear Behavior of an Unreinforced Geosynthetic Clay Liner
H.T. Eid and T.D. Stark
Geosynthetics International 1997 Vol. 4 No. 6
Dry and hydrated specimens of unreinforced geomembrane backed geosynthetic clay liners were sheared against a textured geomembrane to study shear behavior of the geomembrane encapsulated bentonite and results were discussed in this paper.
Fabricated Geomembranes: Advantages and UsesFabricated Geomembranes: Advantages and Uses
Timothy D. Stark, Luis F. Pazmino, Stanford Slifer, and Duff Simbeck
In general, geomembranes come in two distinct types. The first type is flexible enough for folding, transport to a job-site in large panels, unfolding, and seaming to other panels for field testing. The other type cannot be safely folded and instead ships as rolled goods.
Temperature Curtain Improves Salmon HabitatTemperature Curtain Improves Salmon Habitat
By Bob Gee, Bureau of Reclamation, Greg Morris, Bureau of Reclamation & Stanford Slifer, Watersaver CO.
A temperature curtain reaching depths of 100 feet recently replaced curtains originally installed in both the upper and lower reaches of Whiskeytown Reservoir in the early 1990’s. Located at the Whiskeytown Reservoir approximately 10 miles west of the city of Redding, in Shasta County Cali- fornia, the purpose of the replacement curtain is to lower the temperature of the Sacramento River for fish spawning which would restore the Chinook salmon runs to this part of the Sacramento River.
PVC aquaculture liners stand the test of time PVC aquaculture liners stand the test of time
E. Newman, F. P. Rohe and T.D Stark Ph. D, P.E
This paper analyses the successful performance of exhumed geomembrane liners over more than 29 years.