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| August September 2009 | Volume 27 Number 4
Geosynthetics in biofilter ensure water quality
Subscribe at www.geosyntheticsmagazine.com
Landfill cover + solar strips = new energy source
Researchers examine seismic performance
Geosynthetics in China—Part I
No matter how you measure performance—best technical support, cost-eff ectiveness, product quality, ease of installation, proven reliability or environmental “green” solutions, Strata delivers.
Get started by visiting www.geogrid.com or calling us today at 800-680-7750 or 770-888-6688.Youʼll gain access to Strataʼs experience-based answers for all your steep slope, retaining wall, andembankment challenges.
www.geogrid.com Con dence runs deep with Strata.
www.geosyntheticsmagazine.com | Geosynthetics 3
| On Site |
36 |8 |
| August September 2009 |Volume 27 Number 4
24 | On the coverThis subsurface biofilter cell system in Southern California was designed and built using a host of geosynthetic materials.
Project Showcase 8 Landfill cover helps promote new energy source
16 Erosion-control mix rebuilds Clyde’s creekbed
24 Geosynthetics in the construction of a Southern California subsurface biofilter cell system By Ronald S. Johnson, Sang-Sik Yeo, and Randy Sundberg
The benefits of geosynthetic materials are perfectly matched for this project.
36 History, development, and future prospects for geosynthetics industries in China Part 1 of 2 By Jingkui Chi
An introduction to China’s geosynthetics production, applications, research, and market supply and demand.
46 Seismic performance of various geocell earth-retention systems By Dov Leshchinsky
Research and innovation: A guide for product development
4 Geosynthetics | August September 2009
| In Situ | | Final Inspection |
Geosynthetics ISSN #0882 4983, Vol. 27, Number 4 is published bimonthly by Industrial Fabrics Association International, 1801 County Road B W, Roseville, MN 55113-4061. Periodicals Postage Paid at Minneapolis, MN and at additional mailing offices. Postmaster: send address changes to Geosynthetics, County Road B W, Roseville, MN 55113-4061. Return Undeliverable Canadian Addresses to Station A, PO Box 54, Windsor, ON N9A 6J5. Orders and changes contact: A Lo, Circulation Coordinator, Geosynthetics , 1801 County Road B W, Roseville, MN 55113-4061 Phone 800 225 4324 or +1 651 222 2508, fax +1 651 631 9334 e-mail: [email protected]. 1-year USA $59, Canada and Mexico $69, all other countries $99, payable in U.S. funds (includes air mail postage). Reprints: call 800 385 9402, [email protected]. Back Issues: call 800 225 4324, www.ifaibookstore.com.
Coming Next Issue | Geotextiles in pavements | Bioreactor cover | “Focus on History” | China
64 |
60 |58 |
6 Editorial Go to this website every day
56 Panorama Geo news and notes from around the world
57 Letters to the editor Comments and a question for the GMA Techline doctor
58 Geosynthetic Institute 30-year anniversary for the first hardcover book on geosynthetics By Bob Koerner
60 Geosynthetic Materials Association GMA helps organize pre-Expo green roof workshop in San Diego By Andrew Aho
61 Calendar
63 Ad Index
64 Administering a certified welding technician course, Romanian style By Ian Peggs
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Strata Systems is now offering a range of cellular con nement geocell products to meet the demands of the U.S. market for slope protection, channel linings, retaining walls and the support of paved and unpaved roads built on soft soils. PRS, the manufacturer of Neoweb™, is the recognized worldwide leader in production of geocells.
Let Strata’s national team of sales managers and distributors show you how Neoweb can solve problems associated with dif cult soils and steep side slopes. isit www.geogrid.com or call us today at 800-680-7750 or 770-888-6688.
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6 Geosynthetics | August September 2009
| Editorial |
| Geosynthetics encourages your contributions of case histories, photos, and field tips. For submittal guidelines, contact Ron Bygness at 800 225 4324 or +1 651 225 6988; e-mail: [email protected]; www.geosyntheticsmagazine.com
Geosynthetics is an international, bimonthly publication for civil engineers, contractors and government agencies in need of expert information on geosynthetic engineering solutions. Geosynthetics presents articles from field professionals for innovative, exemplary practice.
EDITORIAL ADVISORY COMMITTEE*
Melody A. AdamsVista Consultants LLC, USA
Andrew AhoGMA, USA
Sam R. AllenTRI/Environmental, USA
Richard J. BathurstRoyal Military College, Canada
Witty BindraPermathene Pty. Ltd., Australia
David A. CarsonU.S. EPA, USA
Daniele A. CazzuffiCESI S.p.A., Italy
Oscar R. CouttolencGMA, Mexico
Ronald K. FrobelR.K. Frobel & Associates, USA
Stephan M. GaleGale-Tec Engineering Inc., USA
Han-Yong JeonINHA University, Korea
Robert M. KoernerThe Geosynthetic Institute, USA
Robert E. MackeyS2L Inc., USA
Kent von MaubeugeNAUE GmbH, Germany
Jacek MlynarekSAGEOS, Canada
Dhani NarejoCaro Engineering LLC, USA
Roy J. NelsenErosionControlBlanket.com Inc., USA
Jim OlstaCETCO, USA
Ian D. PeggsI-Corp International, USA
Greg N. RichardsonRSG & Associates Inc., USA
Marco A. SánchezML Ingeniería, Mexico
Mark E. SmithVector Engineering, Peru
L. David SuitsNAGS, USA
Gary L. WillibeyESP/SKAPS Industries, USA
Aigen ZhaoTenax Corp., USA
*The Editorial Advisory Committee reviews selected papers, case histories, and technical editorial copy in its areas of expertise. Individual advisors do not review every submission. Statements of fact and opinion are the author’s responsibility alone, and do not imply the viewpoints of Geosynthetics, its Editorial Advisory Committee, editors, or the association.
| Ron Bygness, Editor+1 651 225 [email protected]
Get to this website now … and every day !www.geosyntheticsmagazine.com—the brand new website for Geosynthetics magazine!
Search current and back issues, and find information, projects, and other news not found in the magazine. Source products, applications, services, and markets for your business. Link to advertisers to get what you need now— information, materials, specs, you name it. Content is updated weekly.
And last, but not least, you can read “The Ron & Andrew Blog” featuring far-and-wide commentary from the editor of Geosynthetics magazine and the managing director of the Geosynthetic Materials Association (GMA).
Be Prepared: The 2010 Specifier’s Guide forms are coming to you in SeptemberWho is the person responsible for updating your company’s information in the annual Specifier’s Guide? Let us know, especially if this person has changed, and these electronic forms will land in their e-mail the week after Labor Day … due back by the end of September.
Don’t miss your appearance in the 2010 Specifier’s Guide.
Save this date for this event: GeoFrontiers–2011 March 13–16, 2011, at the Sheraton Hotel in downtown Dallas, TexasGeoFrontiers returns to Texas, as the Industrial Fabrics Association International (IFAI) and GMA team with the GEO-Institute of ASCE and the North American Geosynthetics Society (NAGS) for the best show of the year. The Geosynthetics Research Institute’s annual conference, GRI–24/2011, will also be held at the Geo-Frontiers event in Dallas.
See you there!
Ron BygnessEditor, Geosynthetics magazine
www.geosyntheticsmagazine.com | Geosynthetics 7
PUBLISHERMary Hennessy
EDITORIAL DIRECTORSusan R. Niemi
EDITORRon Bygness
ART DIRECTORMarti Naughton
GRAPHIC DESIGNERHeidi Hanson
NEW BUSINESS DEVELOPMENTSarah Hyland
[email protected] 800 319 3349
ADVERTISING SALESJane Anthone, Terry Brodsky,
Vivian Cowan, Julia Heath, Katie Lang, Mary Mullowney, Sandy Tapp, Elizabeth Welsh
ADVERTISING ACCOUNT COORDINATOR
Shelly Arman [email protected]
CIRCULATION MANAGERMary Moore
CIRCULATION COORDINATORA Lo
INDUSTRIAL FABRICS ASSOCIATION INTERNATIONAL
1801 County Road B W., Roseville, MN 55113-4061, USA +1 651 222 2508, 800 225 4324
(U.S. and Canada only), fax +1 651 631 9334, Web site www.ifai.com.
© 2009 Industrial Fabrics Association International all rights reserved
The official publication of the Geosynthetic Materials Association
The official publication of the North American Geosynthetics Society
}{ Two great companies, one innovative solution.
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To learn more about geomembrane solutions from Firestone Specialty Products800-428-4442 | [email protected] | www.firestonesp.com/ifai5
To learn more about the EPIC System from RESI 763-784-0614 | [email protected] | www.resisolutions.com
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8 Geosynthetics | August September 2009
Project Showcase
Landfill cover promotes new energy source
Project HighlightsTessman Road Landfill Energy Park ProjectLocation: San Antonio, Texas, USAOwner: Republic Services Inc., PhoenixGeomembrane cap: Firestone Specialty Products, Indianapolis Solar strips: United Solar Ovonic LLC, Rochester Hills, Mich.
Photo 1| In San Antonio, Republic Services Inc. is taking energy re-covery to a new level, installing a geomembrane landfill cover with flexible solar technology that will help power a sustainable energy park at the Tessman Road Landfill. Flexible, laminate-type photovol-taic solar collection strips are configured on the geomembrane cap to maximize hours of sunlight throughout the year.
Photo pp 8–9 couresy of CPS Energy. All other photos courtesy of Republic Services Inc.
Energy and waste-disposal companies today recognize that landfills aren’t just burial sites for garbage, but reactors
where gases produced by decomposing waste can be used for energy production.
A great example of this technology is at the Tessman Road Landfill in San Antonio, Texas, where Republic Services Inc. is incorporating a biogas-to-energy recovery system into one of its 213 landfills. But the Tessman Road project is taking energy recovery to a new level, including installation of a geomem-brane landfill cover that includes flexible solar technology that will help power a sustainable energy park.
By combining a first-of-its-kind solar technology with an existing biogas-to-energy system, the company is turning its Tessman Road Landfill into a sustainable energy park. This green energy venture covers portions of the closed areas of active landfills with flexible, laminate-type photovoltaic (PV) solar collection strips (Photo 1).
10 Geosynthetics | August September 2009
New energy source
Photo 2 | The flexible solar laminates are adhered directly to the geomembrane.
The flexible solar laminates, which capture the sun’s rays for conversion into electricity, are adhered directly to the synthetic, green-colored geomembrane (Photo 2) used to cover and close landfill cells as they reach capacity. Unlike traditional rigid solar panels, which are bulky and frequently cost-prohibitive to in-stall, this system uses flexible, nonreflective collection strips less than 0.25in. thick. The flexible solar strips can be configured to maximize the hours of sunlight exposure throughout the year, depending upon a landfill’s design and site contours.
For its demonstration project at the Tessman Road Landfill, Republic Services is partnering with CPS Energy, Greater San
Antonio’s electric and natural gas provider, to deploy 5.6 acres of the 680-acre landfill with the solar energy cover, attaching more than 1,000 flexible solar strips to the landfill’s south-facing sideslope. Republic and CPS Energy will study and document the results of this solar demonstration project for use in the deployment of solar energy covers on other landfills throughout the country.
Construction on the Tessman Road project, approved by the Texas Commission on Environmental Quality (TCEQ), began in December 2008 and became fully operational in March 2009.
and separation –Think TenCate.
There are many dangers lurking in our world…Some visible…some hidden…
TenCate Geosynthetics is the innovative provider focused on delivering the right solution for a variety of environmental problems. As the world’s leading source of geosynthetic materials, we will develop, manufacture, and provide specifi c solutions for your project.
One of the most diffi cult challenges engineers worldwide face is the measurement of a product’s separation capacity. Now, TenCate accurately quantifi es separation by calculatingthe Separation Factor.
And, proper separation and reinforcement can now be fulfi lled simultaneously through the use of only one layer of a High-Performance polypropylene geotextile. Mirafi ® HP High-Performance Geotextiles offer an excellent balance of high-tensile strength at low strains for reinforcement, very good hydraulic properties that facilitate fi ltration and drainage, and high Separation Factors. For a detailed copy of the Separation Factor methodology, please check out our “Tech Note” section at www.mirafi .com or email [email protected].
At TenCate Geosynthetics, we fi nd solutions for your soil separation and reinforcement problems, protecting you from the dangers you don’t see…like bad road conditions caused by weak and failing subgrades.
Think TenCate. TenCate Geosynthetics increases performance, reduces costs, and enables your company to achieve what was once unachievable. For more information call 1-800-685-9990, or visit www.mirafi .com.
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12 Geosynthetics | August September 2009
New energy source
| Closed areas of the 680-acre Tessman Road Landfill are covered with a geomembrane cap.
“As the nation’s largest municipally-owned gas and elec-tric company, we’re proud that our customers’ energy bills are among the lowest in the country,” said Milton Lee, CPS’s general manager and CEO. “We are able to do this by provid-ing a diverse mix of fuels and renewable energy sources that combined offer reliable, cost-competitive electric service. Working together with Republic and the Texas Commission of Environmental Quality, we are at the forefront of yet another useful way to tap the energy resources of landfills for the benefit of our customers.”
Republic says it will cover closed landfill cells with the solar collection strips, adhered directly on the geomembrane cap. The solar strips are configured to maximize hours of sunlight through-out the year. The new solar cover will complement the landfill’s existing biogas-to-energy system, in operation since 2002.
The system collects and processes biogas, which is produced naturally at the landfill through the decomposition of waste.
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14 Geosynthetics | August September 2009
New energy source
The solar strips, which have flexible photovoltaic silicon cells that convert sunlight directly into electricity, will complement the amount of renewable energy provided by the landfill.
With more than 300 days of sunlight per year in San An-tonio, Republic estimates that the energy produced by the two fully-operational systems, will continuously create about nine megawatts of power—enough to power 5,500 area homes.
“As part of our commitment to creating cleaner, greener communities, we’re continually researching, developing and implementing innovative technologies to help us preserve and conserve our natural resources,” said Ted Neura, senior director of sustainable business planning and development for Republic Services.
“The solar energy [geomembrane] cover is easier to inspect, maintain, and repair than a traditional clay cap, and is technically superior in terms of odor control and stormwater management,” said Tony Walker, project manager for Republic.
“Geomembrane covers are already in use across the country, but [we are] the first to integrate flexible solar cell technology to create an energy-producing cover system. We look forward
to working with state regulators across the country to capitalize on the opportunities provided by landfills and, specifically, our efforts to further the country’s energy independence move-ment through new sources of solar power,” said Walker.
Republic has 213 operating landfills in 40 states. The com-pany’s research suggests that as much as 2,350 acres could be covered with solar energy geomembrane covers, depending on regulatory approvals. That could translate into enough solar energy to power up to 47,000 homes per year. Combin-ing that with existing biogas-to-energy technology, and there is the potential to generate enough green electricity to power 300,000 homes.
Sources: Republic Services Inc., PRNewswire
| “Geomembrane covers are already in use across the country … but [we are] the first to integrate flexible solar cell technology to create an energy-producing cover system.”
| Seaming the landfill cover: Republic’s research suggests that more than 2,000 closed landfill acres could eventually be covered with solar-energy geomembranes.
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For over 130 years, Maccaferri has been controlling the forces of erosion and retaining the earth’s soil. We’ve learned a lot since 1879 and apply that knowledge to every product and every project. Our range of products for soil reinforcement, erosion control and road improvement are proven to be the most effective in the industry.
Maccaferri strives to provide a cost effective and dependable environmental solution to every project.
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16 Geosynthetics | August September 2009
Photo 1 | This “after” photo shows the restored tributary winding through the small town of Clyde, N.C.
Project Showcase
Erosion-control mix rebuilds Clyde’s creekbank| A North Carolina town used a portfolio of geosynthetic erosion-control and reinforcement materials to restore a local streambank and relieve safety threats.
| Tom Wedegaertner contributed to this article. He is director of cottonseed research and marketing for Cotton Incorporated. Wedegaertner can be reached at +1 919 678 2369 or by e-mail at [email protected].
Photos courtesy of McGill Associates P.A.
www.geosyntheticsmagazine.com | Geosynthetics 17
Project HighlightsProject/Location: Streambank restoration in Clyde, N.C.Timeline: Construction, December 2008–February 2009Owner/Client: Town of Clyde, N.C. Engineering/Landscaping: McGill Associates P.A., Asheville, N.C.Geosynthetic Products: HydraCX2 Extreme Slope Matrix,
C125BN, SC150BN, coconut wattlesProduct Developer: Mulch and Seed Innovations LLC, Centre, Ala.;
Cotton Incorporated; USDADistributor: North American Green, Poseyville, Ind.
Introduction
During two weeks in September 2004, the town of Clyde, N.C., was pounded by hurricanes Ivan and Frances, both
delivering destructive amounts of rainfall. The small town recovered, but four years later concerns were growing about a badly eroded tributary that skirted through the Haywood County community.
Located upstream of the Pigeon River, the narrow tributary (see “before” Photos 2, 3 and “after” Photo 1) flows behind the town’s fire station, a local bank, and a Methodist church. Historic farming practices had straightened more than 500ft of the east and west banks of this creek, with streambank slopes steeper than 1:1 and vertical bank heights of 11ft (Photo 2).
Destruction from the hurricanes allowed excessive amounts of runoff to rush through this channel at a high velocity, causing accelerated streambank erosion (Photo 3). If further disturbed during other high-flow storm events, the exposed soil and steep vertical slopes could further erode, threatening the stability of its bordering buildings and pushing even more sediment into the French Broad River Basin.
By 2008, the stream bank restoration project was urgent and compelling work for the town of Clyde, located in far western North Carolina. The fire station, bank, and church,
Photo 2 | This “before” photo shows the artificially straightened tributary with steep banks.
Photo 3 | Post-hurricane runoff accelerated creekbank erosion.
agreed to the project and the town was awarded a state grant appropriated from the Hurricane Recovery Act of 2005 (Sen-ate Bill 7).
The proposed restoration plan called for constructing a meandering stream channel at the existing bed elevation and establishing a new flood plain. The addition of a mechanically stabilized earth (MSE) retaining wall would add strength to unstable slopes and native vegetation would create habitat, slow water flow, and beautify the site (see Photos 4–8).
18 Geosynthetics | August September 2009
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aggregate
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Manufactured from high quality polypropylene, TYPAR is a continuous filament, heat-bonded fabric with superior uniformity that separates, reinforces and filters soil particles while letting water pass through freely.
Characteristics:Lower construction costs from reduced aggregate base thickness.
Reduction in construction time from reliable product quality and eas of installation.
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The planDetermined to adopt a low-impact solu-tion, the town of Clyde hired stormwa-ter specialists, McGill Associates, from nearby Asheville, N.C.
“The goal was to enhance the envi-ronmental habitat of the existing site,” said head project engineer J.P. Johns. “Town officials wanted to establish a natural stream corridor and cause minimal disturbance.” This meant con-servative soil displacement, avoiding chemical-heavy remedies, and using biodegradable materials to preserve the natural landscape.
The plan for the 2-acre site was de-signed to both restore and provide a natural stream setting to an urbanized watershed. “The new stream alignment and bank stabilization plans would en-hance the area by providing access to the new floodplain and allow for natu-ral stream functions consistent with riffle/pool/run sequence throughout the reach,” said Johns.
Specifications and installationIn January 2009, Johns and his team completed the planned restoration of the site, including the relocation of the stream channel, decreasing the stream bank slopes and creating a stable, green retaining wall (see Photos 4–8).
To leave the rejuvenation of the site up to Mother Nature, Johns and his team selected and applied a special mix of sustainable erosion-control solutions, each with its own complement to address challenges posed by this project.
To manage soil stabilization, Johns prescribed biodegradable/bionet ero-sion control blankets (ECBs), installed under the mulch to protect the soil from unwanted weeds, filter urban runoff, and reduce erosion of volatile soil during the stabilization process.
Both ECBs feature layers of coconut fiber stitched with biodegradable thread between biodegradable natural-fiber top and bottom nets; one is constructed with Photos 4 & 5 | The addition of an MSE retaining wall added strength to an unstable slope.
Clyde’s creekbank
aggregate
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GEOTEXT I LES
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An Easy To Install, Economical and Proven AlternativeTo More Expensive and Less Effective Construction Materials and Methods.
aggregate
PavementTYPAR is a long-lasting, durable nonwoven geotextile fabric for paved and unpaved roads and surfaces, drainage, waste handling systems, erosion control and landfills.
Manufactured from high quality polypropylene, TYPAR is a continuous filament, heat-bonded fabric with superior uniformity that separates, reinforces and filters soil particles while letting water pass through freely.
Characteristics:Lower construction costs from reduced aggregate base thickness.
Reduction in construction time from reliable product quality and eas of installation.
Reduction in on-going maintenance cost through Typar’s proven performance, toughness and durability over time.
A variety of widths, lengths, and weights ranging from 1.6 osy to 8 osy.
Typar meets the requirements of AASHTO M288 specifications.
Typar Geotextile Rip-rap
Bedding layer
Anchor trenches
P A V E D R O A D S
D R A I N A G E
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e
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20 Geosynthetics | August September 2009
Clyde’s creekbank
a straw and coconut fiber mix and pro-vides a strong double-net structure.
In addition, coconut wattles were placed on the outer bends of the restored channel reach to intercept and absorb water flow and to collect sediment on-site. A classic degradable rolled erosion-control blanket containing 100% coco-nut fibers, the wattles would eventually decompose into the landscaping.
True to Johns’ commitment to a sustainable restoration plan, biode-gradable eco-stakes were used to hold both the blankets and wattles in place rather than traditional metal stakes that can remain present long after the blankets and wattles have returned to the earth.
Once erosion and sediment control were addressed, the issue of establish-ing vegetation on the streambank re-mained. With proposed new side slopes of 3:1, speedy vegetation was impera-tive because the stream would be quick to swell after the first spring rains and potentially wash away anything that was not snug to the earth.
For quick vegetation establishment, Johns selected a hydraulic erosion-control product that is made with mechanically processed straw fibers, reclaimed cotton plant material, and performance-enhancing tackifiers that form a protective layer that holds soil in place. Mixed with a range of seven different native grass seed varieties, as dictated by the North Carolina De-partment of Environment and Natural Resources, Division of Water Quality, it was applied at a rate of 2,000 to 2,500 pounds per acre to the streambanks and the MSE retaining wall—a “living wall” constructed near the fire station (Photos 6 & 7) to stabilize the bank and designed to eventually blend into the surrounding landscape.
“One of the most important goals of this project was to be sure the native grasses and plants successfully germi-nated,” said Johns. “And even though we
Photos 6 & 7 | A geosynthetically-reinforced MSE slope stabilized the creekbank adjacent to the Clyde Fire Station.
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22 Geosynthetics | August September 2009
Clyde’s creekbank
had taken additional precautions to pre-vent erosion, [this] was an added security blanket because it also prevents erosion.”
ResultsThe new floodplain, adjacent to the stream channel, was graded as flat as pos-sible to maximize flow dispersion during high rain-event, bankfull flows.
“The new stream channel was created taking into account the higher volumet-ric flow rates, velocities, and shear forces associated with an urban watershed, as compared to an undeveloped watershed,” said Johns. “It now allows flood flows to reach the floodplain faster in order to re-duce shear stress in the channel and slow velocities throughout the reach.”
The restoration project, with a blend of native grasses and spot-on biodegrad-able erosion-control materials working on its behalf, was regularly watered by seasonal spring rainfall and began to ger-minate within two weeks. A month later, a healthy stand was apparent, and two months later, 18-24in. grasses covered the Clyde streambank (Photos 1 & 8).
“In February, not even a week after it had been sprayed, we experienced sig-nificant snowfall,” said Johns (Photo 9). “We wondered what effect the freezing temperatures and snowmelt would have on the newly applied product, but there were no adverse effects, no loss of prod-uct, and the vegetation continued to grow healthy and strong.”
Johns insisted that installing this mix of products, each with a specific purpose for this project, created a system that pro-vided excellent erosion prevention while establishing a stand of native vegetation at the same time.
“Equally as important,” he added, “is that none leaves a carbon footprint—only a stable, functional, and safe environment for the town of Clyde.”
Photo 9 | Even after a February snowfall, “there were no adverse effects, no loss of product, and the vegetation continued to grow healthy and strong” (see page 16).
Photo 8 | The stabilized creekbank was designed to eventually blend into the surrounding landscape.
24 Geosynthetics | August September 2009
Photo 1 | Construction procedure of the biofilter cell: geomembrane liner installation for the bottom of the cell (inset photo). Startup placement of geogrids and matrix tank modules (above).
| Ronald S. Johnson, P.E., G.E. ([email protected]) is a geotechnical engineer, and Sang Yeo, Ph.D. ([email protected]) is a senior staff engineer, both with Geosyntec Consultants. Randy Sundberg, P.E., is a project engineer with the Irvine Ranch Water District.
Geosynthetics in the construction of a Southern California subsurface biofilter cell systemBy Ronald S. Johnson, Sang-Sik Yeo, and Randy Sundberg
Photos and figures courtesy of Geosyntec Consultants
www.geosyntheticsmagazine.com | Geosynthetics 25
Introduction
The primary benefits of geosynthetic materials are the flex-ibility to accommodate a variety of configurations and as a
nonreactive barrier for environmental isolation. These benefits are perfectly matched for this project: construction of a subsur-face biofilter cell system for the removal of selenium and nitrate using many types of geosynthetic materials.
For the last 25 years, water quality in San Diego Creek in Southern California has been affected by excessive sediments and nutrient levels. The state of California and U.S. Environ-mental Protection Agency (EPA) regulations required the estab-lishment of limits (i.e., total maximum daily loads—TMDL) on the amount of pollutants that can be discharged into Newport Bay. (San Diego Creek drains approximately 80% of the total area tributary to Newport Bay.)
Photo 2 | Placement of granular media matrix inside of the cell.
Project HighlightsProject: Demonstration of field-scale biofilter cell system Location: Irvine, Calif.Purpose: Verification and evaluation of field-scale effectiveness and
practicality of subsurface biofilter cell system for removal of selenium and nitrate from dry weather flows in Peters Canyon Channel
Clients: Irvine Ranch Water District (www.irwd.com)Engineer/Designer: Construction Quality Assurance (CQA):
Geosyntec Consultants (www.geosyntec.com)Contractor: CDM ConstructionGeosynthetics: • Geomembrane:GSE40-milsmoothgeomembraneand
60-miltexturedgeomembrane • Geotextile:Mirafi1160N • Geogrids:TensarbiaxialgeogridBX1500 • Geonet:GSEHyperNet • Geonetcomposite:GSEFabriNet • Geopipe:PVCperforatedpipe
26 Geosynthetics | August September 2009
Subsurfacebiofilter
To meet this EPA requirement, the Irvine Ranch Water District (IRWD) developed a plan to address regional water quality treat-ment. The plan included the Cienega Filtra-tion Facility adjacent to the Peters Canyon Channel that is specifically for removing selenium from dry weather low flows.
The selenium TMDL is based on meet-ing the chronic California Toxics Rule (CTR) criterion of five parts per billion (ppb) for protection of aquatic health in dry weather flows. Selenium concentra-tions in dry weather flows in the Peters Canyon Channel typically range from about 30–50 ppb, but can be much higher at groundwater seeps and weep holes. The current selenium concentration levels are not harmful to humans but have potential to bio-accumulate.
Concept of biofilter cellThe project was designed to pass dry weather flows that are diverted from Peters Canyon Channel through an organically augmented biofilter cell, which was com-posed of a gravel matrix and constructed using many categories of geosynthetics.
The flows are amended with a carbon source to feed bacteria and create anoxic (oxygen-deficient) conditions in the biofil-ter cell. Under these conditions, common forms of selenium (i.e., selenate and sel-enite) are converted into elemental forms of selenium, which have relatively low toxicity and are encapsulated by bacteria growing on the bed materials (e.g., gravel) in the biofilter cell.
The subsurface natural treatment sys-tem consists of three major systems: • intakeandpretreatmentsystem.• biofiltercell.• finishedwatersystem.
The intake and pretreatment system includes an intake wet well and pump, self-cleaning strainer, bag filter, and elec-tron donor tank. The biofilter cell was created using geosynthetic materials and granular media matrix. The finished water system includes an oxygenation system and finished water pump.
Photos 3–5 | Top—Construction of side walls with geogrid, matrix tank modules, and welded wire form (WWF) and compaction of granular media matrix. Center—Completion of side walls and compaction. Bottom—Encapsulation using geomembrane.
28 Geosynthetics | August September 2009
Subsurfacebiofilter
The biofilter cell is the primary treat-ment component of this project. As sum-marized in the Table 1, the biofilter cell consists of a coarse inert aggregate bed wrapped in an impermeable geosynthetic system. Raw water is pumped from Peters Canyon Channel, amended with electron donor, and injected into the biofilter cell through a piped header system.
Within the biofilter cell, an active biofilm is grown, which attaches to the aggregate. The biological activity helps to create anoxic conditions that are fa-vorable for the conversion of soluble se-lenium compounds to insoluble colloids and precipitates. The insoluble selenium precipitates are adsorbed to the biofilm and sequestered within the biofilter cell. Hydraulic retention time and electron donor feed rate are the variables that can be adjusted to maintain the desired environmental conditions.
Summary of Biofilter Cell Characteristics
Characteristics Summary
Dimensions 200ft(L)x40ft(W)x10ft(H)
Media ¾ minus crushed aggregate
Totalvolumeofbiofiltercell 80,000ft3
Estimatedeffectiveporosity 23%
Estimatedliquidcapacity 18,400ft3(~137,650gallons)
Design flow 0.3cfs(~135gallonsperminute)
Table 1 |
Cover soil
Backfill
Geomembrane
Geotextile
Geomembrane
Geotextile
Geotextile
Geonet
Geocomposite
Subgrade Nottoscale
Geopipe
MatrixTank Modules
Geogrid
Figure 1 | Schematic cross section of biofilter cell
Granular media
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30 Geosynthetics | August September 2009
Subsurfacebiofilter
Summary of biofilter cell characteristics Key geosyntheticsConstruction activities consisted of in-stalling an infiltration gallery in the Peters Canyon Channel, the subsurface biofilter cell, a process area (pump and equipment housing), and a re-oxygenation system. The biofilter cell was constructed using geosynthetics and was covered with 3-4ft of native soil to allow for the develop-ment of a future recreational field. A geosynthetic liner system consists of:• anHDPEgeomembrane,installed
to keep the biofilter cell isolated and impermeable.
• anonwovengeotextile,usedtoprovideboth separation and cushion for protection of the geomembrane.
• ageonet/geonetcomposite–abiplanarHDPE geonet and nonwoven geo- textile–used to collect gas generated by bacteria from the biofilter cell.
• abiaxialpolypropylenegeogrid,usedto allow for the perimeter 10-ft vertical walls and for the biofilter cell to transi-tion into future treatment biofilter cells. The construction sequence is sum-
marized as follows: 1. Subgrade preparation2. Placement of 60-mil textured HDPE
geomembrane for the bottom of the biofilter cell
3. Biofilter cell wall construction using geogrid
4. Compaction of granular media matrix5. Geotextile wrapping the biofilter cell
as the separation between granular media matrix and geomembrane
6. Installation of smooth geomem-brane to encapsulate the biofilter cell
7. Placement of geonet on top of the biofilter cell
8. Placement of geotextile on the side walls of the biofilter cell as the sepa-ration between geomembrane and backfill soil
9. Placement of geonet composite on top of the biofilter cell
10. Piping11. Backfilling and covering
Photos 6–8 | Top—Installation of the geomembrane liner on side walls and corners. Center—Installation of vertical monitoring pipe penetration and CQA testing using spark testing. Bottom—Installation of sidewall pipe penetrations.
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32 Geosynthetics | August September 2009
Subsurfacebiofilter
Photo 9 | Geomembrane installation on the biofilter cell.
Geosynthetics installation significance1. A total of 30 PVC piping penetrations through the liner system of the biofilter cell were constructed: 18 monitoring ports on top of the biofilter cell (i.e., ver-tical pipes) and 12 perforated pipes for inflow, outflow, and gas collection onto the side walls (i.e., horizontal pipes).
Prefabricated HDPE geomembrane boots were fitted over the PVC perforated pipes and extruded to the geomembrane liner. After the extrusion welding, copper wire spark tests were performed for non-
destructive seam testing. A probe with a current was passed above the seam with 25mm (1in.) distance between the probe and the seam, and any sparks indicated that a hole was present.
A neoprene gasket and caulking was inserted between the geomembrane boot and PVC pipe annular space and supported in place with two stainless steel band clamps. The caulking was cured for two to three days after which the stainless steel band clamp was se-cured to the pipe. After the comple-
tion of pipe installation, geotextile was wrapped onto the boot as a cushion material during the backfilling of soil.
2. Geomembrane liner on the side walls was protected by an inside and out-side geotextile layer from granular media matrix and backfill.
The double-track fusion welding was mainly performed for the side wall seaming. The double-track fusion seams were non-destructively tested using the air pressure test as performed on the top and bottom geomembrane liner systems. At the corners
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34 Geosynthetics | August September 2009
Subsurfacebiofilter
Photos 10a & 10b | Backfill and cover after completion of the biofilter cell construction.
of the biofilter cell, the geomembrane liner was folded and extrusion welded.
3. Two different types of HDPE geomembrane (i.e., 40-mil smooth geomembrane and 60-mil textured geomembrane) were welded together using extrusion welding techniques.
Prior to the welding, asperity of the 60-mil textured geomembrane was grinded and removed. The extrusion welds were tested with the vacuum test method. The test results indicated that these two products could be satisfactorily welded using this technique.
ConclusionsDesign and construction of the biofilter cell were successfully implemented using major categories of geosynthetic materi-als due to the flexibility of geosynthetic materials to accommodate a variety of design configurations. Geosynthetics provided a nonreactive barrier for envi-ronmental isolation of the biofilter cell.
Perhaps the greatest challenges with this application of geomembrane were the vertical welding and the abundance of pipe penetrations. To the extent pos-sible, vertical welding should be limited by prefabricating larger portions hori-zontally and assembling them in a man-ner that requires little vertical welding. The abundance and variety of specialized geosynthetics provided the designers with a “toolbox” of materials and, thus, the flex-ibility to develop creative solutions to this challenging environmental issue.
AcknowledgementsThisprojectwasfundedbytheIrvineRanch Water District.
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36 Geosynthetics | August September 2009
| The author is vice president of the Chinese Chapter of IGS and an advisor to the Chinese Technical Association on Geosynthetics. He is president and general manager of Shanghai Hejie Tech & Trading Co. Ltd.
| Part 1 of 2
History, development, and future prospects for geosynthetics industries in ChinaBy Jingkui Chi
| The Hengshan Dam and Reservoir is located in the northernmost part of Shanxi Province in north-central China. It was the first double-curvature arch dam in China.
Photos courtesy of the author
www.geosyntheticsmagazine.com | Geosynthetics 37
Abstract
This article presents an introduction to the development of China’s geosynthetics production, applications, testing,
and research, and discusses the market supply and demand as well as development trends.
1. Introduction1.1 Development of geosynthetics in ChinaThe production and application of geosynthetics in China started in the late 1970s. Those materials used in some small hydraulic engineering projects were mostly made through braiding techniques with narrow widths.
Development was slow through the 1980s. Geosynthetics then were mainly woven fabrics with poor quality and few were considered for engineering applications. By the 1990s, under the development and requirement of national economic construction, geosynthetics witnessed a burgeoning growth. Some advanced equipment and assemblies were imported from Germany, Italy, France, Japan, and Switzerland.
Meanwhile, homemade equipment appeared in the market, which increased product variety, improved product quality, and changed product structure. Braided, woven, nonwoven, synthetic, and composite products appeared and were used in thousands of projects, with an accumulated usage of more than 0.5 billion m².
China suffered severe flooding disasters in 1998, but the adoption of geosynthetics in flood control, dam repair, and other hydraulic engineering projects moved forward.
In 1999, the Ministry of Water Resources selected 50 hy-draulic projects using geosynthetics as models, thus further
pushing forward the application and development of geo-synthetics in China. Moreover, with the improvement and modification of geosynthetic equipment, designs, processes, measurement, regulations, and theoretical research, China’s geosynthetic materials entered a new era in the past decade.
A “geo-textile collaboration network” had been established in 1984andgrewintotheChineseTechnicalAssociation/Geosyn-thetics by 1995. As a first-class national academic organization, this group attracted more than 600 members. After entering the International Geosynthetics Society in 1990, China established its Chinese Chapter (CCIGS) with more than 100 individual members and four group members. CCIGS has organized and participated in international and regional symposiums and ex-hibitions in the United States, Austria, France, Singapore, South Korea, Japan, and other countries. This participation worldwide enhanced the academic communication and market education between China and the rest of the world.
1.2 Classification of geosyntheticsCurrently, there are no unified classification rules and there is no significant difference in the existing classification methods. According to manufacturing methods, geosynthetics can be classified into four categories:
TextilesWovens: braided (plane-braided and round-braided methods), woven (plain and twill woven), knitted (warp knitted and stitch-bonded).
Nonwovens: mechanical reinforcement (needlepunched), chem-ical bonded (adhesive spraying), thermal bonded (hot rolling).
| Left—The Xin’anjiang Dam, Hydropower Station, and Reservoir is located on the Xin’anjiang River in a subtropical area of Zhejiang Province in southern China. The reservoir, one of the largest in Asia, contains 21.6 billion m3 of water. Right—The Baiyunyuan Hydropower Station is located in Tonglu County, Zhejiang Province, in southern China.
38 Geosynthetics | August September 2009
Geosynthetics in China
| Demand for geomembranes is particularly strong for hydraulic engineering and environmental protection projects.
Geomembranes (calendering, blow molding) Polyethylene (PE), polyvinyl chloride (PVC), chlorosulfonated polyethylene (CSPE).
GeosyntheticsComposite geomembranes, composite geotextiles, plastic drainage belts and drainage pipe, prefabricated drainage.
OtherGeotextile bags, geogrids, geocells, geo-technical bands and tubes, geonets, geosyn-thetic clay liners (GCLs), extruded polysty-rene (EPS), drainage and waterproofing.
1.3 Application of geosyntheticsWoven textile productsBraiding and knitting products are widely used in engineering products. In China, braided products have occupied a large proportion, especially in the application of flood control and rush emergency. The use of large sandbags in the construction of embankments, dams, and marine reclamation land is also considerable.
Woven products are used in mattresses as bottom protection, slope protection, geomembrane bags, and other projects that require a relatively high intensity. As newly developed products, knitting products (mainly made of PET filaments and glass fibers) are of good quality that can be used for reinforcement.
The application of braiding products is mainly in the area of hydraulic engi-
neering projects, such as the Shanghai Chen-Hang Reservoir (above, right), deep-water channel regulation projects in Changjiang Estuary, the Shanghai Pu-dong international airport project, the Shanghai Waigaoqiao power plant, the Shidongkou ash dam, Tianjin harbor construction, as well as for marine rec-lamation land and uses for flood control and flood prevention.
Nonwoven productsIn China, needlepunched PET staple fiber products are common, with dozens of large-scale manufacturers. Yet there are more than 10 spunbond PET filament manufacturers, some with imported equipment, others using domestic equip-ment. Therefore, Chinese nonwoven products are mainly of needlepunched staple fibers, with a width of 4m–6m and massof300g/m2to400g/m2. The appli-cations for nonwovens grows every year, especially in hydraulic engineering, but also in highway, railway, environmental protection, airport, coastline, and other engineering projects.
Application of synthetic productsIn China, the manufacturing of synthetic products started relatively late. Until the 1980s, Britain-imported Netlon equip-ment was used to produce geogrids.
At that time, geomembranes were only used in agriculture greenhouse films and had few applications in en-
gineering products. In the late 1990s, the development of products such as geogrids and geomembranes had been promoted to meet the demand of en-gineering construction. Today, with a significant improvement in quality and variety, geogrids are manufac-tured both uniaxial and biaxial.
For geomembranes, the diameter and thickness of blow molding types has increased, and plastic extrusion and cal-endering products have been launched. Other synthetic products such as geo-cells and three-dimensional vegetative netting have also been developed.
The major applications for these synthetic products includes seepage-control materials used in hydraulic engineering and environmental pro-tection, reinforcement of soft slab foundations and retaining walls, and three-dimensional netting for seeding slope stabilization.
Major projects include anti-seepage for the hydro-junction retaining dike in Wangfuzhou, Han River (1.1 million m2
of geomembrane); Shenzhen River har-nessing project (216,000m2 of geomem-brane); dam reinforcement in the Three Gorges project with a geogrid usage of 530,000m2; geocell reinforcement from Lanzhou Airport to Yinjiazhuang Road (58,000m2). Further, geomembranes are widely used in the landfills of large cities such as Beijing, Shanghai, Tian-jin, and Hangzhou. In short, synthetic
| Shanghai Chen-Hang Reservoir
www.geosyntheticsmagazine.com | Geosynthetics 39
products have an extensive application range and a large development poten-tial in China.
Application of composite productsComposite products are processed by com-bining two or more geosynthetic products.
Familiar products include compos-ite geomembranes (one textile with one membrane, two textiles with one mem-brane, and three textiles with two mem-branes) used in anti-seepage projects, and in drainage belts used in reinforce-ment applications. When combined with vacuum pressure to accelerate founda-tion consolidation, construction time is shortened.
Drainage hoses, which have been widely applied in environmental engi-neering and municipal construction, are also common in hydraulic projects to solve the problems of interior drainage. GCLs are primarily used as anti-seepage materials in waste-disposal parks. Com-posite geomembranes are widely used in hydraulic engineering, such as the anti-seepage and bank protection projects on the Yangtze River.
ConclusionAfter some years of stagnation, the Chi-nese geosynthetics industry has recently gained impressive improvements. De-velopment direction of products turns to series type, synthetic type, and com-posite type. Geosynthetic materials enjoy a promising future, with their contribu-tions in geotechnical engineering grow-ing into a new era.
2. Application prospects of geosynthetics in key construction projects2.1 Hydropower constructionAccording to China’s 11th five-year plan (2006–2010), the investment in hydraulic engineering could reach 400 billion yuan ($58.6 billion U.S.).
The basic principle is to vigorously develop hydropower, optimize thermal power, appropriately develop nuclear
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40 Geosynthetics | August September 2009
Geosynthetics in China
power plants, and actively develop new energy sources. Hydropower is regarded as a top priority. The Jinsha River, Ya-long River, and Upper Yellow River hy-dropower bases, as well as the Puluo Ferry and Xiangjia Dam hydropower stations, are scheduled for construction. If necessary, pumped storage power sta-tions will also be built.
As the largest hydraulic project in the world, China’s south-to-north water diversion project has an investment of 535.1 billion yuan ($78.4 billion U.S.), in which 63.4 billion yuan ($9.3 billion U.S.) is designated for the eastern line,
167.7 billion yuan ($24.6 billion U.S.) for the midline and 304 billion yuan ($44.5 billion U.S.) for the western line.
For the eastern line project, the length of the main water conveyance trunk is 1,156km (717mi). At the bottom of the Yellow River, there are two circular tunnels with inside diameters of 9.3m (10.2yd), and the whole length of the tunnel reaches 634m (694yd).
The pollution control project of the eastern line has been divided into two phases. The first phase of the project was recently completed, with the second phase under construction from 2009–
2013. By that time, the number of sewage treatment plants could total 135.
For the midline project, the length of main water conveyance trunk is 1,267km (786mi). Two circular tunnels 7.2km (4.5mi) long with an inside diameter of 8.5m (7.8yd) have 20m (18.3yd) between the two circle centers.
For the western line project, the length of main water conveyance trunk reaches 289km (179mi), with much of this trunk in tunnels. Three import water projects are involved: the Yalong River line, with a length of 131km (81mi); the Tong-tian River line, with a length of 289km
| The Mianhuatan Hydropower Station is located on the Tingjiang River in Yongding County, Fujian Province, in southeastern China.
www.geosyntheticsmagazine.com | Geosynthetics 41
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(179mi); and the Dadu River line, with a length of 30km (18.6mi), all of which are tunnels. This project is scheduled to start in 2010.
Pumping stations use electric power to pump water from downstream to up-stream as storage for the peak periods of electricity consumption. Since the loss of pumped water and anti-seepage con-crete previously used needed frequent repair, the results were relatively poor. Currently, 2mm geomembranes are used to prevent seepage.
Geomembranes indispensable In the construction of some hydrau-lic projects , cof ferdams are bui lt for water closure.
In the past, cofferdam core walls were made of clay. However, some loca-
tions have few clay resources and the selection and processing method of clay core walls needs to be strict, which inevitably stalled construction time-lines. Therefore, geomembranes have been used as substitutes. With the use of geomembranes in the Three Gorges cofferdam, the Fujian Shuikou power station cofferdam, and in other hydro-power stations in China, demand for geomembranes has increased.
China has a large number of con-veyance channels, but there are various problems such as weather aging and poor anti-seepage treatments (e.g., 50% of the transported water lost en route). Recently, geomembranes have been used as anti-seepage materials to solve these issues.
In conclusion, Chinese investment in hydropower construction ranks first
42 Geosynthetics | August September 2009
Geosynthetics in China
in the world. Besides major hydropower projects programmed by the central government, local governments also are investing large sums of money in hy-dropower construction. Hydropower projects remain the biggest market for geosynthetic products, from small, rural plants and reservoirs to large, world-class hydraulic and hydropower projects.
2.2 Applications in environmental engineeringAccording to the 11th five-year plan, China will direct 1,300 billion yuan ($190 billion U.S.) into environmental engi-neering projects.
Along with the rapid development of urban construction, serious problems have been caused by the lack of envi-ronmental protection infrastructures. For instance, garbage has been stacked in open areas or simply buried, while sewage was often discharged directly into urban water systems, causing water quality deterioration and contamination of rivers, lakes, and groundwater. Not solving this problem as soon as possible threatens our living environment.
Geosynthetics have a long history in environmental construction, especially for landfill projects where an anti-seep-age structure has been formed with a variety of geosynthetic products.
Currently, China has more than 800 cities with an urban population total-
ing 450 million, and the number of landfills has exceeded 800. With the fast progress of urbanization, by 2010 there will be 1,200 cities with an urban population totaling 630 million. By that time, every city should have a landfill, which indicates that the use of geo-synthetics would be considerable. The 2010 Expo–Shanghai (May 1–Oct. 31, 2010) should further boost investments in environmental protection.
The largest waste and anaerobic treatment plant has been built in Shang-hai with a total investment of 300 mil-lion yuan ($44 billion U.S.). Covering an area of 66mu (10.9 acres), the plant has an annual garbage treatment capacity of 280,000 tonnes (308,560 tons) and a daily capacity of 800 tonnes (882 tons), including 680 tonnes (750 tons) of do-mestic waste and 120 tonnes (132 tons) of organic waste. Furthermore, through the process of anaerobic fermentation, 4.1 million degrees of electricity could be provided to the east China power grid. The plant was built in 2007 and started trial operation in April 2008. Formal operation began in 2009.
The application of geosynthetics in environmental engineering is compara-tively strict and complicated. Poison-ous solids, liquids, and gases must be regulated. The durability of geosyn-thetics must be considered, including
salinization control, anti-corrosion, anti-microorganism, anti-aging, and other special properties.
In environmental engineering in China, the geosynthetic products are pri-marily geomembranes, geogrids, geotex-tiles, and some GCLs and drainage pipes. For big projects, HDPE geomembranes with a width of more than 4m (4.4yd)and thickness from 2–4mm are generally used. For smaller projects, materials could be designed under the requirement of spe-cific conditions, yet thickness is usually less than 0.5mm. One-sided or double-sided composite geomembranes are used to protect membranes from damage dur-ing the construction process.
2.3 Applications in railway constructionUnder the 11th five-year plan, total in-vestment in railway construction will reach 1,250 billion yuan ($182.8 billion U.S.), with 17,000km (10,540mi) of new railway lines constructed, including 7,000km (4,340mi) of passenger trans-portation lines. By 2010, national rail-way transportation operations will total 90,000km (55,800mi).
The main functions of geosynthet-ics in railway engineering includes anti- filtration, anti-seepage, drainage, protec-tion, and reinforcement. In early stages, needlepunched staple fiber nonwovens were used as filtration for subgrades to
| According to the 11th five-year plan, China will direct $190 billion into environmental engineering projects.
www.geosyntheticsmagazine.com | Geosynthetics 43
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solve the frost boiling and mud pumping problems. As techniques and products improved, there has been an increasing amount of geosynthetics in railway projects, which have effectively conquered many technical problems in railway subgrades.
Besides the application of filtration and drainage for soft subgrades, drainage belts can be inserted as reinforcement, geogrids can be used for reinforcement of subgrades and embankments, and vegetative nets can be used for grass seeding and slope protection. Geomembranes and composite geomembranes are used for anti-seepage applications on embankments, retaining walls, and tunnels. Composite geomem-branes not only control seepage, but also drain water through the composited non-wovens on the membranes.
Currently, railway construction is mainly occurring in the northwest and southwest areas of China, where ap-plications of anti-seepage materials are used. For this application, geomem-branes help produce favorable results. And since it is required that grass be planted on both sides of railway em-bankments, the application of three-dimensional vegetative nets have also expanded in recent years.
2.4 Applications in road constructionChina has invested 1 billion yuan ($146 million U.S.) in the comprehensive re-construction of Qinghai-Tibet Highway, and ll provinces and most cities have also invested large sums of money in highway construction. Both the scale of highway
44 Geosynthetics | August September 2009
Geosynthetics in China
construction and the amount invested are unprecedented.
The applications of geosynthetics in highway engineering is wide. Some ap-plications are similar to railway engineer-ing, but there are also some differences. Generally, geotextiles fit into highway construction for reversed filtration lay-ers, drainage, and to solve the problems of mud and soil pumping and the reflec-tion cracking of asphalt pavements.
Geogrids and geocells are often used in reinforced subgrades and rein-forced retaining walls. Geomembranes and composite geomembranes are mainly used in seepage prevention in tunnels and retaining walls. Bridges, culverts, and retaining walls are the main highway structures and proper geosynthetics selection are required for specific projects.
2.5 Applications at seaports and airportsPort construction includes wharves, port roads, container yards, revetment engineer-ing, and some comprehensive engineering construction such as breakwaters.
If a project is located on soft coastal foundations, reinforcement using geo-synthetic products is needed. Geotex-tiles are used for filtration layers, geo-textile bags for slope protection, and geogrids for foundation reinforcement,
while a geotextile sucking sand pipe bag is used to reclaim land from the sea. A drainage belt is used to drain water and reinforce foundations, and geomem-branes are used as anti-seepage material in buildings and for vacuum preloading sealing material. In short, geosynthetics are absolutely necessary for everything from reclamation of land from the sea to actual port construction.
Airport construction mainly includes aprons, runways, taxiways, buildings in airport terminal areas, and ancil-lary buildings. Most of the airports in southeast China are built on the coast. Some runways can be built only after reclaiming land from the sea. There-fore, airports can involve comprehensive construction requiring the use of many geosynthetic products.
2.6 Applications in mine constructionMine construction requires the building of tailings reservoirs, used to pile waste excreted sand aggregate.
It is necessary to solve any anti-filtra-tion and anti-seepage problems to guaran-tee the security and the stability of the tail-ings dam. For this reason, the selection of geotextiles—instead of sand and stone—as the filtration layer and the use of geomem-branes and composite geomembranes for the anti-seepage material is preferred.
Currently, of the thousands of mines in China, it is estimated that more than 30% use some kind of geosynthetic material.
2.7 Applications in urban constructionUrban construction focuses on traffic and housing construction.
Of course, these projects need to address anti-seepage, especially on the southeast China coast. There the water level is high and the rainy season is long, so the seepage problem becomes even more crucial.
Geomembranes are used to solve the anti-seepage problems for subway tun-nels, underground stations, basements, and underground garages.
It is also a good option to use geo- membrane in city roof greening and tri- dimensional forestation.
2.8 Application in western development constructionChina currently has a strategic decision to make concerning western development.
It is not only an opportunity for the western part of the country, but also an opportunity for further development of the eastern part. Strengthening the cooperation between the two parts of the country is bound to push common development forward.
The total area of the western re-gion of China is about 6,850,000km2
| Geosynthetic materials are necessary for everything from reclamation of land from the sea to actual port construction.
www.geosyntheticsmagazine.com | Geosynthetics 45
Geosynthetics in China
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(2,644,785mi), making up 71.4% of the total land area of China, including 12 provinces, municipalities, and autono-mous regions such as Shaanxi, Gansu, Qinghai, Ningxia, Xinjiang, Sichuan, Chongqing, Yunnan, Guizhou, Tibet, Guangxi, and Inner Mongolia. Every area has its own development advan-tages and development emphasis areas.
The emphasis of the current infra-structure construction is on water con-servancy, railways, highways, airports, and urban construction, as well as pre-serving the ecological environment. All of these require the use of new materials, new processes, and new technologies to ensure the engineering construction quality, increase the construction pace, and reduce project costs.
Currently, China is in the midst of western development and the im-plementation of infrastructure con-struction, with geosynthetics and its application technology the effective and necessary geotechnical engineer-ing material. Geosynthetic materials have been used in tens of thousands of large and small engineering projects in China for many years. They can fully display their excellent characteristics in many applications, such as flood control and emergency, water-saving irrigation by catchment, and environ-mental protection. This geotechnical engineering material and its applica-tion technologies will play a greater role in the western development.
2.9 Major projectsCurrent projects include: South-to-North Water Diversion Project, West-East Gas Transmission, West-to-East Electricity Transmission, and Qinghai-Tibet Railway—four major projects in the 11th five-year plan, all focusing on western development.
China has published the “Implemen-tation Opinion of Policies and Measures about Western Development” to guaran-tee it in policy and law.
Water is the lifeline of economic and social development of China’s western region. There is no shortage of electricity and gas, but the lack of water directly af-fects people’s lives, industrial and agricul-tural production, as well as the need for drinking water for people and animals.
There are solutions to the water prob-lem. One is water diversion and convey-ance. Another is water catchment and storage. Third is water conservation.
It is of utmost importance to solve seepage problems in all construction to ensure that there is no water loss. Using geomembranes is the most economic and effective way, and this has been proven by innumerable construction projects.
Currently, the development of water conservancy construction in western
China focuses on water-saving projects in irrigation districts, water-storage projects in the field, drought resistance and water conservation projects, supplementary ir-rigation, and water supplement projects. All of these projects have to solve the problem of anti-seepage, so the western development needs plenty of geosyn-thetic materials, especially geomem-branes. There is a great market potential here. Other kinds of products should be developed according to the characteris-tics of the western region, as well.
“Geosynthetics in China–Part 2”: October/November issue of Geosynthetics
46 Geosynthetics | August September 2009
| Dov Leshchinsky, Ph.D., is a professor of civil and environmental engineering at the University of Delaware and is a regular contributor to Geosynthetics magazine. His last article, “The case of the percolating water,” appeared in the April/May 2008 issue.
Research and innovation: Seismic performanceof various geocell earth-retention systemsBy Dov Leshchinsky
Introduction
Innovation has always required thinking out of the box. The development of various applications-oriented geosynthetic
products demonstrates this hypothesis. For example, consider geomembranes, geogrids, and geotextiles, and think of landfills, MSE walls, and filters. While geotechnical structures become more cost-effective and have better performance, researchers are rewarded for positively impacting the profession.
An established player in the geocells arena, PRS-Mediter-ranean, envisioned a modification of its standard product to enable new, critical applications. The idea was to develop a new polymeric alloy that combines the desired properties of poly-ethylene and polyester, thus enabling an effective use of geocells as reinforcement for earth retention, load support in pavements and railroads, and more. While exploring the production of such an alloy (called Neoloy®), PRS commissioned research to develop design methodologies. Such research should also imply the desired properties of the new product.
All photos and figures courtesy of the author
This article provides an overview of the research where the use of geocells as an earth-retention structure was explored. The geocell used in the tests was standard, commonly used HDPE and, as such, was not appropriate for long-term reinforcement applica-tions; that is, it was not stiff enough. However, it was adequate for
Editor’s note: Feature articles in Geosynthetics magazine focus on projects and how geosynthetic materials are used in a variety of applications. Very rarely is the focus solely on a specific product, company, or individual. Professor Leshchinsky and I note that this article—particularly the Introduction and Conclusions—departs from this policy in an effort to offer a guideline, an example, of how product development for the geosynthetics industry can be done effectively. We hope these lessons can further advance the geosynthetics industry into the 21st century with much success.—RB
Recorded Peak Ground Acceleration
(PGA) in the Field
Test Number
Applied Peak Acceleration at Base of Shake TableHorizontal Vertical
Loading Stage: Loading Stage:1 2 3 1 2 3
Horizontal: 059gVertical: 0.34g
1 0.46g 0.92g NA 0.21g 0.42g NA
2 0.48g 0.94g NA 0.20g 0.39g NA
3 0.47g 0.95g 1.22g 0.20g 0.37g 0.48g
4 0.41g 0.87g 1.21g 0.18g 0.34g 0.50g
Table 1 |
www.geosyntheticsmagazine.com | Geosynthetics 47
investigation of short-term performance, thus implying the desired long-term prop-erties of a polymer to be used as well as producing the basis for design, especially under severe seismic loading.
The research team included Profes-sor Hoe Ling of Columbia University, Dr. Mohri of the National Research In-stitute of Rural Engineering in Tsukuba City, Japan, and the author. Detailed re-sults were reported by Leshchinsky, et al. (2009) and Ling, et al. (2009).
Ideally, the design of any struc-ture subjected to earthquakes should bebasedontolerablerecoverableand/or permanent displacements. This ap-proach is difficult to implement for rea-sons such as a lack of acceptable criteria for tolerable displacements, highly ran-dom future seismic record, inaccurate identification of in situ soil constitutive behavior, and numerical difficulties in predicting displacements within the ma-trix soil-geosynthetic. The state-of-the-art in seismic slope stability analysis is not yet sufficiently developed to entirely replace the current design practice.
Design of slopes is typically based on limit equilibrium (LE) stability analysis. Pseudostatic slope stability analysis as-sumes an equivalent seismic coefficient, typically in the horizontal direction, which results in additional force components in the limit equilibrium equations, all pro-portional to gravity. Specifying the seismic coefficient as peak ground acceleration (PGA) is likely overly conservative as it considers the maximum seismic forces permanent rather than momentary.
The objective of this study was to quantify a reasonable reduction factor (RF) on the PGA for geocell retention structures. Reduced factors can then be integrated with well-established LE analy-sis to conduct seismic and static design.
Shake table testing programThis shake table is located at the Japan National Research Institute of Agricul-tural Engineering, Tsukuba City, and it
Figure 1a | Test 1: gravity wall with gravel infilled geocell
Figure 1b | Test 2: gravity wall with sand infilled geocell
Figure 1c | Test 3: geocell reinforcement infilled with sand
48 Geosynthetics | August September 2009
Seismicperformance
can excite gross maximum payload of 500kNtoverticaland/orhorizontalac-celeration of 1g; maximum accelerations for lighter payloads can be larger than 1g. The metal testing box containing the geo-cell retention systems was 2m wide, 6m long, and 3m tall. To minimize reflection of waves from the side and rear of the metal box, expanded polystyrene (EPS) boards, 5cm thick, were placed against the testing box walls. To reduce friction with the sidewalls, greased plastic sheet-ing was placed against the EPS.
In all tests, an amplified time record of the 1995 Kobe earthquake was applied to the shake table. The Kobe record used had horizontal PGA of 0.59g and a ver-tical PGA of 0.34g. The peak horizontal and vertical accelerations did not occur simultaneously. Table 1 shows the ap-plied peak accelerations in four differ-ent tests. There were either two or three loading stages.
In the first loading stage, the Kobe re-cord was attenuated in an attempt to verify whether excessive movements occurred. An hour later the second loading stage was applied, amplifying the Kobe record. In Tests 3 and 4, a third excitation was
Figure 1d | Test 4: 5cm-high geocell reinforcement infilled with sand
applied, this time reaching the capacity of the shake table. The third stage nearly doubled the Kobe recorded acceleration. Stage 2 was aimed at developing an active wedge; it was hoped that the third stage would bring about collapse.
In Tests 1-3, the retention system was 2.8m high; in Test 4 it was 2.7m. All re-tention systems were constructed over a 0.2m-thick foundation soil. The geocells, resembling a honeycomb structure, were 0.2m high with internal aperture of ap-proximately 0.21m by 0.21m. The aver-
age face inclination of the systems was 2(v):1(h). The top geocell layer was 2.52m long, much longer than all layers below. This top layer was infilled with compacted gravel. It was assumed that long top layer made of geocell would inhibit crack or even slip surface formation immediately below this layer. Indeed, tests indicated that while numerous small and shallow tension cracks initiated at the crest, none was observed immediately below the long top geocell layer in any of the tests, thus supporting the initial assumption.
Test NumberMaximum Settlement Horizontal Permanent
Displacement of Face [mm]Maximum Settlement
of Crest
1 31 27
2 47 40
3 150 150
4 95 85
Table 2 |
www.geosyntheticsmagazine.com | Geosynthetics 49
Seismicperformance
Figure 1 (a–d) shows the geocell lay-out in each of the four tests. Tests 1-2 represented flexible gravity walls and Tests 3-4 utilized geocell as reinforcement and facing. In terms of economics, the sys-tems in Tests 3 and 4 are about the same. In Test 4 the layout of geocell resembled that of traditional geogrid reinforcement while still acting as 3-D element. Gener-ally, the polyethylene geocell used in the tests cannot be used as reinforcement for sizeable structures since it has low long-term tensile strength. As tested, only suf-ficient short-term properties were needed to resist the seismic loading. However, the lessons should indicate the needed prod-uct improvements in developing Neoweb®, which is made of Neoloy®, as well as pro-duce a simple design methodology. Table 3 |
Test Number Seismic Reduction Factor RFs=a/PGA
1 0.38
2 0.37
3 0.25
4 0.25
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50 Geosynthetics | August September 2009
Seismicperformance
The backfill soil behind the facing and in the 0.2m-thick foundation was fine uniform sand (Median Grain Size = 0.27mm; 0.35% passing sieve #200; Uni-formity Coefficient = 2). The backfill was compacted to 90% of Standard Proctor at a moisture content of 16% yielding a dry unitweightof13.5kN/m3 or moist unit weightof15.6kN/m3. Compaction was done by a handheld vibratory compac-tor. Drained triaxial tests yielded peak strength of ϕ=38 degrees. Unit weight of thecompactedgravelwas19.9kN/m3.
Thin white seams of sand were placed every about 0.4m within the backfill ma-terial. Upon completion of each test, the backfill was carefully excavated to observe dislocations of these seams so that traces of slip surfaces could be identified. In ad-dition, each test was comprehensively in-strumented including pressure transducers, laser displacement gages, accelerometers, and strain gages (Ling et al, 2009).
Results and interpretationAccelerometers embedded within the backfill soil and facing, at several eleva-tions, indicate that magnification of base acceleration was negligibly small. This may not be surprising with flexible re-tention systems as they deform during shaking, dissipating energy and acting as shock absorbers.
Table 2 shows the measured maxi-mum displacements in each one of the tests. Note that displacements were not uniform and, therefore, the term maxi-mum represents a rather narrow zone where it occurs. Also note that for Tests 1 and 2, the maximum applied acceleration was significantly lower than that for Tests 3 and 4 (see Table 1). Overall, considering the severity of the applied seismic excita-tion, the recorded values do not imply a catastrophic failure (e.g., see Figure 2 for typical post-shaking appearance).
Generally, the displacements reflect a well-developed active wedge where the shear strength of the soil is mobi-lized. Sufficient strength and stiffness Figure 3a | Test 2 (applied excitation was 159% of Kobe’s)
Figure 2 | Test 2: Post-earthquake (159% of Kobe’s PGA) frontal view—see excavated section of same wall in Figure 3a (below).
www.geosyntheticsmagazine.com | Geosynthetics 51
Seismicperformance
Figures 3a–c | Post-shaking exhumed sections through backfill and geocell (Note: Dislocations of white sand seams indicate locations where slip surface developed and soil strength was fully mobilized).
of a geocell will enable acceptable struc-tural long-term performance with even smaller displacements.
Post-test exhumation of the retention systems while measuring dislocations of the white sand seams helped in estab-lishing the location of the active wedge surface (e.g., see Figure 3, a–c). This enables complete limit equilibrium (LE) stability analysis where the soil strength is fully mobilized rendering an active wedge, meaning the factor of safety on soil strength, Fs, equals unity.
To find an equivalent seismic coef-ficient for design, it is convenient to defineseismicreductionfactor,RFs=a/PGA, where a is the equivalent pseudo-static seismic coefficient. RFs for each test was determined using the recorded PGA that caused an active wedge to develop without rendering excessively large displacement combined with an adequate LE analysis.
The pseudostatic acceleration in the LE analysis was adjusted to render Fs of unity; i.e., to reflect the existence of an active wedge. The locations of the predicted and observed active wedges were compared and used to assess the predictive value of the analysis. It is
Figure 3b | Test 3 (applied excitation was 205% of Kobe’s) Figure 3b | Test 4 (applied excitation was 205% of Kobe’s; note the sections through the 5cm-high geocell reinforcement.)
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52 Geosynthetics | August September 2009
Seismicperformance
noted that in LE design, one would input a(=RFs PGA) to obtain adequate seis-mic stability where the factor of safety, Fs, under pseudostatic conditions is typically about 1.1. In fact, if one had to design the tested retention systems, use of RF and Fs>1.1 would have produced smaller displacements than those re-ported in Table 2.
LE stability analysis was performed using program ReSSA (www.geopro-grams.com; also see Leshchinsky and Han, 2004). Rotational (Bishop) and translational (Spencer) analyses were conducted to determine the RFs. The safety map feature (Baker and Leshchin-sky, 2001) facilitated the process. (For example, see Figure 4.) While the ob-served slip surface emerged between the second and third geocell facing layer, thenumericallypredictedsurface(ata/PGA=0.35) emerged along the interface between the geocell and the foundation soil. However, the safety map shows that practically this is an insignificant differ-ence, as the safety factors for any pre-dicted slip surface emerging at the lower geocell layers is within about 1–2%. Such an observation affords confidence in the predictions, especially when comparing Figures 3a and 4; i.e., the observed and predicted traces of slip surfaces, respec-tively. Figures 5a and 5b show the pre-dicted active wedges and their respective RFs values; they can be compared with the observed wedges shown in Figures 3b and 3c, respectively.
Apropos Figures 3c and 5b: As can be seen, contrary to a common legend, these figures demonstrate that slip sur-faces can develop through the reinforce-ment. Such “internal” global instabil-ity can occur when the reinforcement is too soft or weak. Clearly, while the HDPE geocell used was adequate to test a design-oriented analysis, it lacks long-term strength to serve as reinforcement. However, it enables one to establish the desired properties in geocells so it can serve as soil reinforcement. Figure 5a | Test 3: predicted active wedge using Bishop Analysis
Figure 4 | Test 2: Safety map rendered by Program ReSSA (3.0) using Spencer Method and pseudostatic analysis.
Rotational (Bishop) and translational (Spencer) analyses were conducted to determine the RFs. The safety map feature (Baker and Leshchinsky, 2001) facilitated the process.
Figures 5a-b | Predicted critical slip surfaces in geocell-reinforced retention systems
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54 Geosynthetics | August September 2009
Seismicperformance
Figure 5b | Test 4: predicted active wedge using Bishop Analysis
Table 3 (page 49) summarizes the re-duction factors that are implied by the testing program when a pseudostatic LE is used. As can be seen, for geocell gravity systems, RFs of about 0.4 are adequate. For geocell-reinforced soil systems, RFs of 0.3 are adequate.
ConclusionsCurrent practice of designing reinforced or unreinforced slopes and walls is to identify the local PGA and use a frac-tion of it in a pseudostatic analysis. This fraction is the reduction factor for pseu-dostatic analysis.
The Kobe earthquake was used as a reference for an excitation to identify this coefficient. It is likely that if another excitation was used, the reduction factor would be different. However, the Kobe earthquake was significant in terms of damage to slopes and walls, thus quali-fying it to serve as a good reference for calibrating this reduction factor and the associated seismic coefficient.
Tests results are compared with a pseudostatic limit equilibrium analysis. The predicted failure mechanisms are similar to those observed in the tested geocell retention systems. The seismic coefficients required to produce failure in the analysis were much smaller than the actual peak value obtained in the tests. For the geocell gravity wall, the seismic reduction factor, RFs, needed to render failure is about 0.4. For geocell reinforced retention systems RFs is about 0.3.
The FHWA (2001) guidelines for reinforced steep slopes allow for RFs of 0.5. Hence, compared with this work, the FHWA recommendation is slightly con-servative. The IITK (2005) recommenda-tion for unreinforced slopes of one-third of the Peak Ground Acceleration is amaz-ingly close to the measured results.
Tests 1 and 2 show that gravity walls made of geocell can perform well under seismic loading. Such gravity systems may be economical for walls up to 3-4m high. Tests 3 and 4 show that a
reinforced system, made entirely of geocell and soil, can be effective and likely economical.
The tests reported herein are rel-evant to short-term performance when considering the utilized HDPE geo-cell. However, without improvement, HDPE geomembranes are not suitable for long-term applications. Problems of durability related to leaching of ad-ditives, oxidation, and to UV exposed facing should be addressed. Large thermal contraction and expansion of outer cells due to daily and seasonal temperature changes combined with high intrinsic thermal coefficient of the geocell material could lead to progres-sive failure initiating at the outer cells. Stress cracking of exposed facing could occur in low temperature. Low stiffness and strength may lead to significant creep having poor long-term dimen-sional stability.
Considering the objectives of this research, PRS-Mediterranean received guidelines for developing the new poly-meric alloy, Neoloy®, and thus improve its Neoweb® system, facilitating its use in retention systems. It also obtained design
tools enabling utilization of the Neoweb® in demanding applications considering long-term performance.
ReferencesBaker,R.,Leshchinsky,D.,2001.“Spatialdistributionsof safety factors,” ASCE Journal of Geotechnical and Geoenvironmental Engineering,127(2),135–145.
FHWA,2001.Mechanically Stabilized Earth Walls and Reinforced Soil Slopes Design and Construction Guidelines, PublicationNo.FHWA-NHI-00–043.Elias,V.,Christopher,B.R.,Berg,R.R.
IITK,2005. IITK-GSDMA Guidelines for Seismic Design of Earth Dams and Embankments, prepared by Roy, Dayal, Jain. IndianInstituteofTechnologyKanpurandGujaratStateDisaster Mitigation Authority.
Leshchinsky,D.,Han,J.,2004.“GeosyntheticReinforcedMultitiered Walls,” ASCE Journal of Geotechnical and Geoenvironmental Engineering,130(12),1225–1235.
Leshchinsky,D.,Ling,H.I.,Wang,J-P,Rosen,A.,Mohri,Y.,“EquivalentSeismicCoefficientinGeocellRetentionSystems,”Geotextiles and Geomembranes,27(1)2009,pp.9-18.
Ling,H.I.,Leshchinsky,D.,Wang,J.P.,Mohri,Y.,Rosen,A.,2009.“Seismicresponseofgeocellretainingwalls:experimentalstudies,”ASCE Journal of Geotechnical and Geoenvironmental Engineering,135(4),515-524.
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56 Geosynthetics | August September 2009
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New Caltrans guide for geotextilesA new design guide for using “subgrade enhancement geotextiles” (SEG) in road construction has been produced by the California Department of Transpor-tation (Caltrans).
The 18-page document is intended to assist pave-ment design engineers in five areas:1. What are SEGs and what functions do they serve.2. How to determine if geotextile materials are
needed for a project.3. How to determine the material’s engineering
properties.4. How to install and how to construct new pave-
ment using geotextiles.5. Calculating cost savings, in the amount of
aggregate, by using geotextiles.For more information and to examine this guide:
www.dot.ca.gov/hq/esc/Translab/ope/Subgrade- Enhancement-Geotextile-Guide.pdf
GEO news and notes from around the world
Abstracts invited for geosynthetic materials workshopAbstracts are invited in support of the workshop Geosynthetic Materials Durability: Field and Laboratory Experiences, sched-uled for Jan. 29, 2010.
This workshop will focus on all types of geosynthetic materi-als durability in both covered and exposed applications. The four-part workshop includes long-term field experiences under various environment conditions: accelerated weathering studies, polymers, and additive packages that constitute the final material’s formulation. Part four is a summary of workshop content by a panel of experts.
Sponsored by ASTM International Committee D35 on Geosynthetics and the Geosynthetic Research Institute (GRI), the workshop will be held in conjunction with the Jan. 27-29 standards development meetings of the ASTM committee. The workshop will focus on all types of geosynthetic materials durability in both covered and exposed applications.
Titles and abstracts for this workshop must be sent to both workshop cochairs by Sept. 30, 2009. Based on their appropri-ateness and acceptance, the formal program will be developed. Titles and extended summaries (2 to 5 pages) will then be required by Nov. 30, 2009. The final abstracts will form the information booklet that will be distributed to all participants at the workshop. All oral presentations will be on PowerPoint with a time allocation of 15-25 minutes, depending on the response to this solicitation.
Additional information is available at www.astm.org/d35work110.htm or by contacting workshop cochairs Sam R. Allen, TRI/Environmental Inc., Austin, Texas (+1 512 263 2101, [email protected]); or George R. Koerner, Geosynthetic Institute, Folsom, Pa. (+1 610 522 8440, [email protected]).
Infiltrator acquires Ring GroupInfiltrator Systems has acquired Ring Industrial Group, manu-facturer of the EZflow brand of geosynthetic aggregate drain-field systems.
EZflow products are established in the onsite industry with 15 years of installations in more than 30 states and Canadian provinces. The EZflow geosynthetic expanded polystyrene sys-tem is engineered for optimal absorption efficiency. Modular bundled configurations allow installations in septic drainfields and drainage applications.
With the addition of the EZflow product line, Infiltrator, based in Old Saybrook, Conn., is the largest septic products company in the onsite industry with a combined 2.5 million systems installed across North America (www.infiltratorsys-tems.com).
Thrace-Linq commissions nonwovens equipment A new nonwoven production line has been commissioned at the Summerville, S.C., facility of Thrace-Linq.
The company’s advanced production line includes a fiber-opening and blending system, oven and dryer, calender, wind-ing and slitting system, and automated packaging.
For more information: www.thracelinq.com.
www.geosyntheticsmagazine.com | Geosynthetics 57
FGI offers short courseThe Fabricated Geomembrane
Institute (FGI) will offer “Constructing with Fabricated Geo-membranes—Flexibility, Choices, and Superior Performance” Oct. 23 in Denver.
This course is presented by Timothy Stark, Stan Slifer, John Heap, Daren L. Laine, Bill Shehane, Stuart Lange, Andrew Mills, and Gary Kolbasuk, among others. Course participants are eligible for 8 PDHs from the University of Illinois.
Those involved with the design, con-struction, operation and closure of potable water and irrigation ponds, floating cov-ers, canals, landfills, waste water lagoons, secondary containment, golf course ponds, decorative applications, corrective action activities at closed sites are encouraged to attend this course.
The registration fee of $100 includes one day of instruction, short course notes, refreshments, and lunch. Government per-sonnel and students are eligible for dis-counted admission. Advanced registration is required and the registration deadline is Oct. 14, 2009.
For more information: www.fabricated-geomembrane.com, +1 217 333 7394.
TenCate introduces new drainage geosyntheticTenCate Geosynthetics has introduced Mirafi MiraGreen™D for site drainage ap-plications for engineers and architects de-signing environmentally sound projects.
The product is a nonwoven drainage geotextile composed of 30% (LEED calcu-lated) recycled content and it can be used in a wide variety of drainage applications. Its manufacturing process is designed to reduce dependence on virgin petroleum-based resins.
A product description sheet and tech-nical data sheet can be viewed and down-loaded at www.mirafi.com.
| Letters to the editor |
Comments and a question for the GMA Techline doctor| Red or white?
To the editor:I am writing to respond to the April/May issue of Geosynthetics,
specifically to the GMA Techline Q & A (pp. 50-52). The GMA Techline is a valuable element of the magazine, one that I read fervently.
I have several comments and a question for Dr. Koerner.The question from Claudia (p. 50) on the comparison of standard
results from ASTM and ISO methods is a good discussion topic—possibly an article in Geosynthetics describing, in general, the salient differences between the methods would be of assistance to those wrestling with international specifications.
The question from Gabriela (p. 52) asking about references to work done on pH and geogrids in masonry units is a recurring question that both GSI and the FHWA have spent considerable time and effort on. While many in the industry have seen the reports and research, many in the general engineering community simply are not aware of the work done to date on the FHWA guidelines.
Finally, however, I must take issue with the response Dr. Koerner provided to the last question, from John (p. 52), relating to geocom-posite drainage. Specifically, has the good doctor given due consid-eration to red wine as well as white? There are numerous blends and many vintners who produce excellent reds, be they a cabernet, shiraz, merlot, etc. While white wine may be the summer drink of choice for many, nothing beats the delicious taste of a nice glass of chianti after a hard day at the office.
Regards,John Paulson, P.E.REDI Engineering Inc.Alpharetta, Ga.
58 Geosynthetics | August September 2009
| Geosynthetic Institute |
30-year anniversary for the first hardcover book on geosyntheticsBy Bob Koerner, Geosynthetic Institute/Drexel University
In the late 1970s I was in the habit of regularly inviting speakers to make presentations to my geotechnical classes
at Drexel University. Two were very memorable: Bill Ragen of Mirafi and Bill Witherow of Carlisle. Their respective topics were “filter fabrics” and “pond liners” and, in truth, I didn’t associate them with one another within the modern context of geosynthetics that we do today.
Shortly thereafter, and following several small consulting projects, two other events occurred that were meaningful. One was the 1977 conference in Paris, France, entitled International Conference on the Use of Fabrics in Geotechnics, and the other was a chance meeting between an editor of the John Wiley & Sons book company (by the name of Dan Morris) and a good friend, Joe Welsh, of the ground modification firm, Hayward Baker. Dan, who had seen the proceedings of the Paris conference, suggested to Joe that he write a book on construc-tion fabrics and Joe, being too busy, suggested that he and I do it together. It was interesting to me from the per-spective that this was a new field of endeavor and that it would be a hard-cover book.
When I was proceeding through my formal education, all books that we used were hardcover. This con-tinued throughout my university years at Drexel, Columbia, Dela-ware, and Duke. There simply were no softcover books at that time. When softbound books and paperback conference proceedings began to appear, my thoughts (and perhaps those of others) were that they were not quite “finalized.” Many were published by university print departments and updated annually. As an example, many soils laboratory books fell into this category until Lambe’s hardcover manual eventually settled the issue. A hardbound book was felt to be archival and belonged permanently on one’s bookshelf.
At any rate, my initial thought regarding the possibility of a new hardbound book was that the information base was certainly sparse. But upon further reflection (remember the “publish or perish” concept was deeply entrenched in all of academia, including Drexel University, then as it is now), I
started gathering all available publications and manufactur-ers’ literature and formed a table of contents. While the focus was indeed “fabrics,” certainly impermeable fabrics (aka, pond liners) were also considered. As such, the book was written between 1978 and 1979 and published as a 267-page hardcover in 1980 by J. Wiley and Sons Inc., under the title, Construction and Geotechnical Engineering Using Synthetic Fabrics.
The individual chapters were: 1. Overview and Background of Synthetic Fibers, 2. Construction Fabrics, 3. Fabric Use in Separation of Materials, 4. Fabric Use in Reinforcement, 5. Fab-
ric Use in Drainage, 6. Fabric Use in Ero-sion Prevention, 7. Fabric Use as Forms, 8. Impermeable Fabrics, 9. Guidelines and Current Research and Development Activities, 10. Several Appendixes and a “units” conversion table.
There were a few numerical examples, but it was not a complete textbook in that there were no homework problems and the references were obviously lean at this early stage of the technology.
We (Joe Welsh and I) were delighted with the book’s initial reception in that its sales were good and, more importantly, my phone never stopped ringing. Clearly, my subsequent decision to go completely into this newly emerging field was obvi-ous and well beyond all other research interests that I had at the time (e.g., deep foundations, acoustic emissions, ground-penetrating radar, etc.).
The one cloud that arose was a book review by Dr. Alan Haliburton of Oklahoma State University who reviewed the book with the ending comment that the book was, “too much salad and not enough meat and potatoes.” For those of you who remember Alan, you can understand the context of his com-ment. What it did for me, however, was to propel me onward to a “meat and potatoes” book, which emerged six years later as the first edition of Designing With Geosynthetics, published in 1986. Work is now beginning on the sixth edition of this textbook.
Some time after the publication of the first book in 1980, I learned from England’s Peter Rankilor that our Construction and Geotechnical Engineering Using Synthetic Fabrics book was very close to not being the first hardbound geosynthetics book. It seems that he had submitted his own manuscript to the
www.geosyntheticsmagazine.com | Geosynthetics 59
| Geosynthetic Institute |
Wiley office in London about the same time as we submitted ours to Wiley’s New York office. Of course, neither London nor New York knew of the two respective book topics and, more importantly, Wiley in London lost all of Peter’s artwork, photographs, and drawings, forcing him to do everything all over. (Remember that these were the days before computers and an all-electronic publication system.) The delay caused him at least a year, which resulted in his book appearing a year later than ours, in 1981.
At any rate, the Koerner/Welsh hardcover book of 1980 certainly put me on the map and (fortunately) I never looked back. All subsequent research at Drexel University, along with courses, students, and projects, was focused on geosynthetics and it has not stopped to this day. Geosynthetics is a marvelous field of endeavor and a technology that has had, has, and will continue to have, an awesome growth and benefit to society. I am delighted to have been a part of this growth and hope to continue for another 30 (well, maybe not 30!) years.
| Final Inspection |
HDPE. They had three chances on 3m-long strips to make a satisfactory weld from which central samples were cut for peel and shear testing at TRI in Austin, Texas. Each candidate could send only one sample of each type of weld for testing.
Equipment would seemingly work for some people but not for others, but the more experienced welders seemed to have no problems at all. It got very hot and sweaty! Cristina, Valentin’s daughter, had put them all through a dry run of the welding and testing before the actual test, but nerves were still evident. No discussion or help was allowed. Each person did his own “QC” shear and peel testing to assess the quality of the welding,
One of the first welders used all of his allowed material before he was satisfied, putting a large dent in the available time. Extrusion-weld quality varied significantly from constant and smooth to quite rough, depending on the welder’s experience. It averaged about three hours for each person to do all require welding. When machines malfunctioned, the operator made his own repairs or moved to the unused machine. Cutout samples were labeled by the welder and were separately bagged for shipping to TRI. We finished at 23:30 hr. We had dinner in the car park at a McDonalds!
Cristina’s comments: We had one month to prepare for the exam (the theoretical and
the practical parts). During this time, we composed more than 500 possible questions and we ran a couple of tests, the last one a simulation of the actual event! We created the normal Romanian exam conditions. All of the participants passed this test! Ciprian Ciobanu, the leader of the Iridex geosynthetics installer team, prepared them for the practical part. He was changing the equipment settings all the time to make sure that each person was capable of setting the machines correctly. We did our best to pass the IAGI examination! We knew that we would become the first company in Europe welders to receive IAGI certifica-tion, so we welcomed the challenge!
On Monday morning I gave a lecture, translated by Mircea Pascaru and Cristina Feodorov, on “Geomembranes: Successes and Failures” to about 55 people at the Technical University of Bucharest. Some
of the guests came from the Romanian Environmental Ministry. They were very interested in how installations of geomem-branes are done and how they must be checked. Waste management systems are an important topic in Romania right now.
In the afternoon, we first went to an international courier company to send the sealed packages containing the samples and the examination papers to TRI. Then we visited the Hall of the People, really Ceaus-escu’s palace, looking out over the Avenue of the People that was modeled on the Champs Elysées, but it is1m longer and 1m wider! The gall of the man and his separa-tion from the people were unbelievable.
On Tuesday morning, we were delivered back to the Bucharest airport for our flights home via Paris and Atlanta.
All but one person became certified welding technicians after the welds were tested by TRI, where they had to meet the GRI.GM-19 specifications for seam shear strength/elongation and peel strength/separation. Congratulations to Ciprian Ciobanu, Viorel Cotrau, Radu Dinu Cezar, Florin Vlaicu, Cristian Gheorghe, Stan Sterea, Valerica Martin, and Constantin Popescu for successfully becoming IAGI Certified Welding Technicians!
And many thanks to the Feodorovs and to Mircea Pascaru for their excellent hospitality.
Continued from page 64
| Mircea Pascaru and Cristina Feodorov worked on translating the questions for the written CWT test.
60 Geosynthetics | August September 2009
| Geosynthetic Materials Association |
GMA helps organize pre-Expo green roof workshop in San Diego
A pre-show program titled “How to design green roofs and landscapes” will be held
Tuesday, Sept. 22, 5:30–8:30 p.m., at the San Diego Marriott Hotel & Marina, in conjunction with the 2009 IFAI Expo at the San Diego Con-vention Center Sept. 23–25.
This workshop is free to licensed architects (see details below). It will provide insightful in-formation on the use of geosynthetic and textile materials that promote the design of sustainable, energy efficient environments and buildings. The workshop is organized by the Industrial Fabrics Association International (IFAI) and the Geosynthetic Materials Association (GMA).
IFAI members, please note that an additional registration fee applies for this workshop, as it is not included in a Full Business Package to IFAI Expo-’09. (See costs below.)
Benefits of attending this course• 2.0continuingeducationhours(CEHs)• NetworkingreceptiononSept.22• FreeadmissiontotheIFAIExpoTradeShowSept.23–25• Learnhowgeosyntheticmaterialsareproducingsustainable,
energy efficient environments • Examineon-sitegeosyntheticmaterialsandlearnabouttheir
performance characteristics • Learnthestepstoasuccessfullandscapeprojectwithgeo-
synthetic materials • Getnewideasfordesigninglandscapes,greenroofs,and
related building structures• Collectresourcesandcontactstogetstartedonprojectsusing
geosynthetic materials • Enjoyanetworkingreceptionandmeetgeosyntheticsexperts• ReceiveafreesubscriptiontoFabric Architecture and Geo-
sythetics magazines
Costs and Continuing Education Hours This workshop is not included in the Full Business Package to IFAI Expo. Costs: Before Sept. 12—$99 for IFAI members, $149 nonmembers; after Sept. 11—$129 members, $179 nonmem-bers. Students receive a 70% discount; college and government employees get a 40% discount.
The program offers 2.0 CEHs at the conclusion of the pro-gram. Architects must register by contacting Barbara Connett, [email protected] or +1 651 225 6914 with RSVP, contact information, and state license number.
Tentative schedule6–6:30 p.m.: Keynote speaker Glen Schmidt, FASLA,
Schmidt Design Group, “Creative Solutions for Sustainable Environments”
6:30–7 p.m.: Mechanics and Construction of Geosynthetic Technology, Bruce Dvorak, ASLA, Department of Landscape Architecture & Urban Planning, Texas A&M University
7–7:20 p.m.: Examples of Green Roofs and Landscapes using Geosynthetic Technology, Allan Wingfield, AIA, product manager, Colbond Inc.
7:20–7:50 p.m.: Practical Steps for Designing and Installing Green Roofs and Landscapes, Angie Derman, Tecta America
7:50–8 p.m.: Workshop Summary, Boyd Ramsey, GSE Lin-ing Technology Inc.
– Andrew Aho, Managing Director, GMA, [email protected]
| The Chicago City Hall green roof project included a drip-irrigation system, fed partially by water collected from the adjacent penthouse roof.
www.geosyntheticsmagazine.com | Geosynthetics 61
September
2–5 SeptemberGeoAfrica-2009Cape Town, South AfricaThe first African regional conference on geosynthetics is Sept. 2–5, 2009, in Cape Town.
The Geosynthetics Interest Group of South Africa (GIGSA), under the auspices of the International Geosynthetics Society (IGS), will host the first regional conference in Africa on geosynthetics. The theme for the event is “Geosynthetics for Africa.” The conference will include an exhibition for the specification and trade of geosynthetics for users in Africa and for those interested in a business entry into the continent.
For complete information on the conference, including registration information, key dates, technical and social programs, and exhibition and sponsorship options: +27 21 559 4574, fax +27 21 559 4574 086, [email protected].
To register, exhibit, or for more information: www.geoafrica2009.org, www.gigsa.org/GIGSA/index.htm
9–11 SeptemberShoreline Protection: Practical Coastal Engineering Design and PracticeUniversity of Wisconsin–MadisonTopics include: coastal processes, data gathering, and planning; mechanics of wave, water, and wind interactions; design of breakwaters, jetties, groins, seawalls and revetments, armoring, and rock quality.
This course is prepared for: city, county, and state agency officials; regulators, planners, and developers; civil and geotechnical engineers; contractors and construction personnel; geologists and hydraulic engineers.
Participants can earn 21 professional development hours (PDH) and 2.1 Continuing Education Units (CEU).
To reserve a room, call 800 356 8293 or +1 608 257 6000 and indicate that you will be attending this course under group code 6595.
Course location: Pyle Center, 702 Langdon St., Madison, Wis.; course fee: $1,095.
For more information: +1 608 262 0785; www.epdweb.engr.wisc.edu/webK816
23–25 SeptemberRemTech Expo 2008Ferrara, ItalyThe 3rd edition of Remediation Technologies Exhibition will be held at the Ferrara Exhibition and Conference Centre in Ferrara, Italy.
The event is organized by the Ferrara Fiere Congress and by coordinator, Dr. Daniele Cazzuffi.
The expo will feature: remediation technologies; removal and encapsulation of asbestos; characterization, investigation, and instruments for analysis, inspection, and monitoring; brownfields and real estate; management and planning.
To register, exhibit, or for more information: +39 0532 909495, [email protected], www.remtechexpo.com
October
1–2 OctoberLRFD for Geotechnical Engineering FeaturesUniversity of Delaware, Newark CampusLoad and Resistance Factor Design (The Design Platform for the 21st Century), presented by Jerry A. DiMaggio, P.E., and Dov Leshchinsky, Ph.D., and facilitated by UD’s Engineering Outreach.
web: www.engr.udel.edu/outreach/short-courses/LRFDGeoTechFeatures/index.html e-mail: [email protected]
5–9 OctoberSardinia-2009: 12th International Waste Management and Landfill SymposiumSardinia, ItalyFor conference details and more information: Anne Farmer, Eurowaste srl, via Beato Pellegrino 23, I-35137 Padova, Italy; +39 049 8726986; fax +39 049 8726987, [email protected].
For more information: www.sardiniasymposium.it
19–21 OctoberWaterproof Membranes 2009 Düsseldorf, GermanyThis conference provides a forum for manufacturers and users of waterproof membranes, as well as their supply chain and researchers, to discuss the latest trends in markets and technologies.
A small exhibition runs alongside the conference. Waterproof Membranes 2009 aims to cover a range of subjects including: membrane materials and additives, material selection, market trends, applications, legislation, standards and testing, manufacturing technology, and more.
Conference location: Swissôtel Düsseldorf/Neuss, Düsseldorf, Germany, +49 (0) 2131 77 00, [email protected], www.swissotel.com
For more information: Sally Humphreys at Applied Market Information Ltd. (AMI), +44 (0) 117 924 9442, Fax: +44 (0) 117 989 2128 sh@amiplasticscom, www.amiplastics.com
23–25 SeptemberIFAI ExpoSan DiegoAt the San Diego Convention Center, San Diego, Calif., U.S.A. The largest specialty fabrics show in the Americas, offering hundreds of exhibitors and high-impact, cutting-edge symposiums and workshops.
For information, contact show management at [email protected], or visit www.ifaiexpo.com.
| Calendar |
62 Geosynthetics | August September 2009
| Calendar |
19–22 OctoberCitiesAlive 2009TorontoIn partnership with the city of Toronto and the World Green Roof Infrastructure Network, Green Roofs for Healthy Cities has announced the inaugural CitiesAlive World Green Roof Infrastructure Congress, taking place at the Sheraton Centre in downtown Toronto, Canada.
Addressing the theme “Green Roof Infrastructure: A Global Solution to Climate Change,” the objectives of the CitiesAlive Congress are to raise awareness of the benefits of green roof infrastructure and to build capacity of the green roof infrastructure market through an international exchange of information, and via local education, training, and accreditation opportunities.
More than 1,000 participants within the building design, development, construction, and management sectors, as well as policymakers, government officials, NGO representatives, students, and engaged members of the public are expected to participate in the event.
To register, exhibit, or for more information: www.citiesalive.org
20–22 OctoberGeotextile Tubes: Coastal, Structural, and Dewatering Design and ApplicationsUniversity of Delaware, Newark CampusThree course options are offered to meet specific needs, presented by Douglas A. Gaffney, P.E., and Dov Leshchinsky, Ph.D., and facilitated by UD’s Engineering Outreach.1. Coastal and Structural Engineering
Applications (Oct. 20–21).2. Dewatering and Other Environmental
Applications (Oct. 21–22).3. The full geotextile tube course
(Oct. 20, 21, 22).
web: www.engr.udel.edu/outreach/short-courses/GeotextileTubes/index.html e-mail: [email protected]
28 October–1 NovemberSociety of Hispanic Professional EngineersWashington, D.C.The nation’s largest technical conference for Hispanics offers a lineup of educational, technical, networking, and career programs to support college students and professionals.
The conference promises to be particularly popular for job seekers, since more than 300 organizations are projected to attend, hiring in the fields of science, technology, engineering, and math.
Other highlights at the 33rd SHPE events include award presentations, workshops, engineering and design competitions, career fair, and corporate tours.
For registration and more information: www.shpe.org
November
10–11 NovemberGeosynthetics Middle East 2009 Dubai, UAESKZ announces the 2nd International Conference of Geosynthetics Middle East in Dubai, UAE.
This year’s topics include polymer developments; products (geomembranes, geotextiles, geogrids, geocomposites, erosion control products, geopipes); testing, quality assurance, and certification; installation and welding; applications, projects, and case studies; durability and lifetime.
Dr. Helmut Zanzinger will chair the seminar.
Conference site: Radisson SAS Hotel—Dubai, UAE; www.dubai.radissonsas.com
For more information: Irina Bender at SKZ–TeConA GmbH , Friedrich-Bergius-Ring 22 Wuerzburg, 97076 Germany; +49 931 4104-436 [email protected], www.skz.de
11–13 NovemberMSEW & Reinforced Soil SlopesUniversity of Delaware, Newark CampusMechanically stabilized earth walls and reinforced soil slopes—including LRFD and allowable stress wall design sections based on AASHTO–LRFD Specifications, 4th Edition, 2007, presented by Dov Leshchinsky, Ph.D., and James G. Collin, Ph.D., P.E., and facilitated by UD’s Engineering Outreach.
web: www.engr.udel.edu/outreach/short-courses/msew-rss/index.html e-mail: [email protected]
16–18 NovemberNational Tribal Transportation ConferencePhoenix
The 12th annual NTTC is at the Pointe Hilton Tapatio Cliffs Resort in Phoenix this year.
Featured at the November event will be a focus on stimulus funding and the reauthorization of federal highway legislation.
The exhibit hall at this event will be open Monday night, Nov. 16, and all day Nov. 17–18.
For more information about sponsoships, exhibiting, or registration: 800 262 7623, [email protected], www.ttap.colostate.edu
www.geosyntheticsmagazine.com | Geosynthetics 63
✦ GMA indicates advertiser is a member of the Geosynthetic Materials Association, a division of IFAI
| The Geosynthetic Materials Association actively identifies, assesses, analyzes and acts upon market growth opportunities and issue that affect its member companies. The activities of the association are proactive in nature and focus on five areas: Engineering support • Business development • Education • Government relations • Geosynthetic industry promotion
Visit www.gmanow.com, Contact: Andrew Aho [email protected], 800 636 5042.
| For your convenience, a list of advertisers, including hot links to their web sites, is available at www.geosyntheticsmagazine.info. When you contact an advertiser in this issue, please tell them that you saw their ad in Geosynthetics.
| Advertisers Index |
13 Huesker, Inc. ✦ GMA 800 942 9418 www.huesker.com
31 Insulfoam, LLC www.insulfoam.com
43 Invisible Structures Inc. ✦ GMA 800 233 1510 www.invisiblestructures.com
15 Maccaferri Inc. ✦ GMA 800 638 7744 www.maccaferri-usa.com
31 NAUE America Inc. ✦ GMA +1 404 504 6295 www.naue.com
41 Parker Systems Inc. 866 472 7537 www.parkersystemsinc.com
41 Presto Geosystems 800 548 3424 www.prestogeo.com
23 Propex ✦ GMA 800 621 1273 www.geotextile.com
1, 5 Strata Systems Inc. ✦ GMA 800 680 7750 www.geogrid.com
Cv2 Agru America ✦ GMA 800 373 2478 www.agruamerica.com
45 American Wick Drain Corp. 800 242 9425 www.americanwick.com
39 BTL Liners ✦ GMA www.BIGLINERS.com
29 Carlisle SynTec 800 479 6832 www.carlislegeomembranes.com
43 Checkmate Geosynthetics Inc. ✦ GMA +1 604 824 4963 www.checkmategeogrid.com
21 DEMTECH Services Inc. 888 324 9353 www.demtech.com
19 Fiberweb ✦ GMA 800 321 6271 www.TyparGeotextiles.com
7 Firestone Specialty Products ✦ GMA 800 428 4442 www.firestonesp.com/ifai5
2 GSE Lining Technology Inc. ✦ GMA www.gseworld.com
51 Synder Mfg. Inc. ✦ GMA 800 837 4450 www.snyderman.com
Cv4 Tenax Corporation ✦ GMA 800 356 8495 www.tenaxus.com
11 TenCate Geosynthetics ✦ GMA 800 685 9990 www.mirafi.com
27 Thrace-LINQ, Inc. ✦ GMA 800 445 4675 www.thracelinq.com
29 Trelleborg Building Systems AB +46 370 481 00 www.trelleborg.com/waterproofing
39 Vector Engineering Inc. +1 530 272 2448 www.vectoreng.com
| The bolded advertisers are exhibitors at IFAI Expo 2009.Be sure to visit their booths at the show, which will be held at the San Diego Convention Center, San Diego, CA on September 23–25, 2009. For more information on IFAI Expo2009, please visit www.ifaiexpo.com.
www.ifaiexpo.com
64 Geosynthetics | August September 2009
| Final Inspection |
hour time limit; only a couple stayed to the bitter end. Fortunately, we still had time for a late dinner with Valentin’s family.
The driving in Bucharest was interesting, to say the least—either very wide boulevards or narrow old streets; the surroundings of a modern city anywhere in the world but still a distinct aura of Ceausescu’s influence.
The youngsters in Valentin’s family appreciated their free education but were happy to have their own choice of job and the ability to live well without it being taken away. We also heard some fascinating sto-ries from Valentin about leaving to work internationally, making good money, and the difficulties of bringing it back to start his own business at home when Ceaus-escu had gone. Obviously, it has all paid off, since Iridex is one of the largest and most forward-thinking construction companies in the country.
On Saturday morning, after all of the equipment was gathered, we were ready to start the hands-on tests at 09:30 hr. We had two fusion and two extrusion welders, but there was only sufficient power in the rented college workshop to have two running at any time!
The order of testing was pulled out of a hat. Each welder had to double-wedge weld: (1) 1mm smooth HDPE to 1mm smooth HDPE; (2) two different thicknesses of HDPE—one smooth, one 1.5mm tex-tured; and (3) 1mm smooth LLDPE to 1mm smooth LLDPE, starting from scratch—clean wedges, adjust gaps, set nip roll pres-sure, and set temperatures and speeds.
They also had to extrusion weld 1mm smooth LLDPE to 1mm smooth LLDPE and 1mm smooth HDPE to 1mm smooth
| Ian Peggs, P.E., P.Eng., Ph.D., is president of I-CORP International Inc. and is a member of Geosynthetics magazine’s Editorial Advisory Committee.
IAGI certified welding technician course, Romanian styleBy Ian Peggs
When I knew that Lyn and I were going to EuroGeo4 in Edinburgh
(September 2008), we decided to take ad-vantage of the cheap European airfares to spend a few vacation (What a concept!) days in Prague.
Having already proctored an IAGI welder certification course for Permathene in New Zealand during a business trip Down Under, I asked Laurie Honnigford if there was any company in Eastern Europe that might want to run a CWT certification course. Iridex, in Bucharest, Romania, she said immediately.
So we made arrangements with Valen-tin Feodorov, president of both his com-pany, Iridex, and of the Romanian chapter of the International Geosynthetics Society (IGS). We extended our award ticket to Bucharest at a saving of 5,000 miles (How does this work!?), so planned to spend three days in Romania.
We arrived at the Bucharest airport early on a Friday afternoon and were driven di-rectly to the technical college where the multiple-choice written test and hands-on welding tests on high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) were to be held.
I was safely guarding the written test books. The intent was to go straight into the written test. Of course, the written test was in English and most of the welders (nine in all) did not speak or read English! Needless to say, the Spanish version of the test was no help either.
We thought of translating each ques-tion in turn and presenting it verbally in Romanian, then allowing sufficient time so every question would have equal time, but that would not allow backtracking or reviewing previous questions and answers.
| Classroom with participants taking the written certification test (top). In addition to a written test, hands-on welding proficiency was also required (bottom).
Continued on page 59
Another option was to translate three or four questions at a time and to project them on a screen.
In the end, there was only one answer: Since full translation would have to be done anyway, we would make a completely printed translation of the test. This took about four hours, during which time all nine participants waited nervously for the test! We started quite late. There were just a few explanations of the translation required. Most of the guys finished before the two-
Photos courtesy of Ian and Lyn Peggs
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