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| October November 2007 | Volume 25 Number 5

Subscribe at www.geosyntheticsmagazine.info

Defendingthe coastline in Germany

Geomembranes and butterfl ies?

SRW challenges-Part 1

Avalanche protection

in Iceland

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8 | Reinforced roads were required for the construction of wind turbines in New York.

| In Situ |

| On Site |

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Geosynthetics CrosswordBy Myles Mellor

| Final Inspection |

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26 | Developers used design-build expertise to address aesthetic features at this SRW supporting a roadway.

22 | New protection applications are installed on islands off the German coast.

| October November 2007 |Volume 25 | Number 5

16 | On the coverAvalanche protection is the objective with these geosynthetically reinforced barriers above a small town in northern Iceland. Cover design by Missy Schlegel.

Coming Next Issue | The 2008 Specifier’s Guide

EditorialThe Bridge

Guest ColumnNow is the timeBy John Henderson

PanoramaASTM committees propose new standardsPlastics prediction

Geosynthetic InstituteConnecting with the Techline: Dr. Koerner again offers sound advice to letter writers

Calendar

Advertisers Index

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Project ShowcaseReinforced roads for wind farm Geomembranes and butterflies

Avalanche protection in northern IcelandBy Ron BygnessUse of geosynthetics in a reinforced-soil barrier system

Defending the coastline in northwest Germany New PU coating composite applied on Frisian islands

Challenges in building SRWsBy Michael Simac and Blaise FitzpatrickPart 1: How to contract for MSE walls

Testing produces design guidanceBy Michael RobesonFollow this new product through the testing process




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The BridgeI was on that bridge.That bridge … you know the one.I was on the bridge that collapsed …

you know the one … it was on TV.The bridge that collapsed.The Interstate-35W bridge in Minneapolis.I was on that bridge every day.Every day.To and from.At 7 a.m.At 4 p.m.Every day.That bridge collapsed.13 people.13 people died.I didn’t die.I was on that bridge at 4:01 p.m. that day.The day the bridge collapsed.August 1, 2007.4:01 p.m.—I was there … cement slurry splashing on my car.The bridge collapsed at 6:01 p.m.I was alive … at home … safe with my wife … watching it on TV.I was alive to see the TV news.I saw the TV news live.I was alive.They were dead.I was on that bridge.

| Editorial |

| Ron Bygness, Editor+1 651 225 [email protected]


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| 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].

Geosynthetics (formerly GFR) is an international, bi-monthly publica-tion for civil engineers, contractors and government agencies in need ofexpert information on geosynthetic engineering solutions. Geosyntheticspresents articles from field professionals for innovative, exemplary practice.

EDITORIAL ADVISORY COMMITTEE*

Melody A. AdamsKennec Inc., 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.


mailto:[email protected]



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PUBLISHERMary Hennessy

[email protected]

EDITORIAL DIRECTORSusan R. Niemi

[email protected]

EDITORRon Bygness

[email protected]

ART DIRECTORMarti Naughton

PRODUCTION MANAGERRussell Grimes

[email protected]

GRAPHIC DESIGNERMissy Schlegel

PRODUCTION COORDINATOR/GRAPHIC DESIGNER

Kristen Evanson

ADVERTISING DIRECTORSarah Hyland

[email protected] 319 3349

ADVERTISING SALESJane Anthone, Terry Brodsky,Vivian Cowan, Julia Heath,

Karen Lien, Mary Mullowney, Susan Parnell, Elizabeth Welsh

ADVERTISINGACCOUNT COORDINATOR

Shelly [email protected]

CIRCULATION MANAGERMary Moore

[email protected]

ASSISTANTCIRCULATION MANAGER

Susan [email protected]

INDUSTRIAL FABRICSASSOCIATION 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.

© 2007 Industrial Fabrics Association International all rights reserved

GeosyntheticMaterials Association

The official publicationof the GeosyntheticMaterials Association

The official publicationof the North AmericanGeosynthetics Society

Geosynthetics ISSN #0882 4983, Vol. 25, Number 5 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 offi ces. Ridealong enclosed. 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: Sue Smeed, Asst. Circulation Mgr., 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: subscriptions @ifai.com. 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 800 207 0729, [email protected], www.bookstore.ifai.com

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When I was asked to consider becoming Chairman of the GMA Executive Council in January, my im-mediate reaction was: “No way! I already have a full-time job. Why do I need more things to do?”

However, as the next few days passed, a nagging feeling persisted. I began to hear voices (which happens to most people who spend any time in the geosynthetics industry) saying: “If not you, then who? If not now, when?”

My mind was sending me a message that each of us already know about our industry, but often try to ignore: I need to get involved and make a difference. It is easy to sit on the sidelines and complain that the industry has stagnated, that some all-encompassing, ambiguous organization should do a better job of growing our industry, or my industry associa-tion does not care about me.

So, you ask, why am I in this position? Well, I am glad you asked.First, GMA now has a solid strategic plan under the leadership of Andrew Aho, GMA’s Managing Director. An-

drew has a clear vision for the future of the geosynthetics industry and in a short time has focused our efforts on key and effective initiatives—education, government relations, and membership growth. Since Andrew came on board, the

association’s membership has grown by more than 30%, and we now have our first non-manufacturing Executive Council member, TRI/Environmental. Great job, Andrew!

But Andrew and I—and all of the geosynthetics industry—now need your support.

Second, to be a successful industry, there must be an industry voice that provides clear, concise, and accurate information to facilitate the growth of that

industry. Our customers and influencers are longing for an organization that can serve as a clearinghouse for all issues related to geosynthetics. Quite frankly, we have let them down during the past 40 years. We need a strong, dynamic, one-stop shop for our industry. GMA is that organization.

Finally, you need to get involved because you are needed! Your experience, your ideas, your energy—we need it all! Our industry and the future of all of our companies are too important for excuses, past lives, or old issues to stop the dynamic growth of this association. Also, you are missing out by not being involved. The excitement and the momentum currently generated in GMA about the direction of not only our association, but our industry, is contagious.

If you are a member of the geosynthetics industry, then you should be involved in GMA. How? GMA membership is offered on three levels:

Executive Council Membership level is open to companies in the geosynthetic industry. Executive Council members provide the main source of funding and serve as GMA’s board of directors, carrying out the primary activities of the association.General Membership level is open to all members of the geosynthetics in-dustry. General members serve on association committees and help shape the direction of the association.Distributor Membership level is open to all distributors, consultants, and other service providers for the geosynthetics industry. Distributor members serve on association committees and help shape the direction of the association.

Go to the gmanow.com Web site for more details regarding membership.Regardless of your past experiences during the ups and downs of our industry,

now is the time to take action, now is the time to join the momentum. Get on board–it’s going to be a great ride!

•

•

•

| Guest Column |


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Geosynthetic Materials Association

Now is the timeBy John Henderson, P. E.Vice President, Marketing—TenCate GeosyntheticsChairman, GMA Executive Council

…the momentum currently generated in GMA about the direction of not only our association, but our industry, is contagious.

For additional information on GMA, contact:

Andrew AhoManaging DirectorGeosynthetic Materials Association1801 County Road-B WestRoseville, MN 55113-4061Telephone: 1+ 651 225 6907;800 636 5042E-mail: [email protected] site: www.gmanow.com

Geosynthetic

Materials Association




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Project Showcase

| Maple Ridge Wind Farm

Geogrid-reinforced roads aid wind farm’s installation of giant turbines IntroductionDevelopment of the Maple Ridge Wind Farm required stability improvement to the subgrade of 26 miles of ac-cess roads to the locations of the farm’s wind turbines. A successful road design solution resulted following the installation of 463,000yds2 of geogrid.

Project site The Maple Ridge Wind Farm near Lowville in upstate New York is the largest wind farm east of the Mississippi River. With more than 120 wind turbines, the Maple Ridge Wind Farm can produce approximately 240 megawatts (MW) online that provide electricity for about 60,000 residents.

The wind turbines are 260ft tall with rotor blades that are 130ft long.

The American Wind Energy Association estimates that 1 MW of wind generation capacity is the equivalent of 1 mile2 of new forest in terms of offsetting or displacing carbon dioxide from conventional generating sources.

Challenges Development of the Maple Ridge Wind Farm required the subgrade improvement of 26 miles of access roads leading to the wind turbine locations. The access roads needed to withstand constant and heavy traffic from concrete-mixer delivery trucks weighing approximately 50,000lbs., and also trucks hauling 800-ton cranes.

| Bearing capacity analysis determined the usage of geogrids and the proper layer of aggregate to successfully convey vehicles and equipment to the turbine construction locations.

Photos courtesy of C

ontech Earth S

tabilization Solutions Inc.



Project Showcase

Design & Installation First, a design analysis was completed by geotechnical specialist Martin Derby. This analysis contained 2 major components:

• calculating the California Bearing Ratio (CBR) or bearing capacity for each access road.

• determining the amount of aggre-gate material needed for a successful road design.

The CBR calculations required using soil boring information and es-timating the numbers and weights of traffic loads. A 1.4 CBR was deter-mined for an “average” road condition and 0.8 for a “worst case” condition. Once CBRs were calculated, Derby was able to determine the amount of aggregate material needed for both of those road conditions.

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| More than 460,000yds2 of geogrid was installed to stabilize access roads to the wind turbine locations. The turbines (below) are 260ft tall with rotor blades 130ft long. Cranes weighing 800 tons were also brought in on the roads to complete turbine construction.




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Project Showcase

Derby’s analysis and design solution was conducted and presented within 24 hours of his site evaluation. The design solution also included installing geogrid, which required 14in. of NYS-DOT Type 2 aggregate for “average” conditions and 22in. of aggregate for “worst case” conditions with extremely soft soils.

ConstructionAfter a successful test run, the Maple Ridge Wind Farm implemented ap-proximately 463,000yds2 of geogrid for the 26 miles of access roads. The proj-ect also included widening some roads from 16ft to 32ft and installing geogrid under crane platforms. The installation was a successful solution that allowed the site to improve the bearing capac-ity of the soils, reduce the amount of aggregate needed to stabilize the soils underlying the tower access roads, and provide ease of construction.

Similar plans are typically used for roadways, haul roads, rail yards,

runways, construction platforms, and parking lots to increase structural ca-pacity, extend pavement life, and im-prove pavement durability. This system combines geogrid with crushed aggre-gate or granular fill to improve sub-grade and base course performance, all with less undercutting and lower mate-rial costs. The result is more durable and cost-efficient pavement.

Project HighlightsLocation: Maple Ridge Wind

Farm, Tughill Plateau, Lowville, N.Y.

Owner/developer: PPM Energy and Horizon Wind Power Co.

Engineering/design: Contech Construction Products Inc.

Geosynthetic materials: Tensar BX1200 Geogrid

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Project Showcase

Here’s quite a pair:Geomembranes and butterflies| New liner system installed in the Smithsonian’s Butterfly House

Michael Dorsch of Hallaton Inc. and Ron Bygness, editor of Geosynthetics magazine, contributed to this article.


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IntroductionProject title—“Butterflies & Plants: Partners in Evolution”Location: The Smithsonian’s National Museum of Natural History in Washington, D.C.

This immersive exhibit explores the processes and pat-terns of evolution, and provides visitors with a new kind of experience in the National Museum of Natural History (NMNH)—a walk-through living butterfly house.

NMNH will invite visitors to observe the many ways in which butterflies and other animals have evolved, adapted, and diversified together with their plant partners over tens of millions of years.

The specially constructed butterfly pavilion within the exhibit is a walk-though experience featuring hundreds of tropical butterflies in a climate-controlled environment, complete with flower planters and exit vestibules.

Geomembrane lining systemInstallation of a technical geomembrane liner was com-pleted this year during construction of the pavilion at the Smithsonian Institution’s Museum of Natural History Butterfly House in Washington, D.C. The mem-brane was specified in the construction plans in order to develop a series of planters in the pavilion’s enclosed tropical environment.

Photos courtesy of H

allaton Inc.

| An extended view of the geomembrane installations at the planters in the new Butterfly House in Washington, D.C. The planters will offer a simulated natural environment that visitors can walk through.




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The new self-contained exhibit was built on the fourth floor of the NMNH. It offers a simulated natural environ-ment that visitors can walk through and experience without barriers, numerous live, exotic butterfly species and even a pupator that will provide visitors the chance to see new butterflies emerging from their cocoons. The micro-climate necessary to support the various life forms in the Butterfly House incorpo-rates precise temperature and humidity controls. One feature of the climate control system is a series of mist nozzles built into the walls of the structure. The high humidity and moisture provided by these mist nozzles required the in-stallation of a geomembrane liner to contain the moisture within the struc-ture and prevent it from harming any-thing outside of it.

The 45-mil reinforced polypro-pylene membrane was specified by engineers as a containment system and liquid barrier for the Butterfly House’s planters and flooring system.

The sensitive work in relatively close quarters included furnishing and in-stalling the liner system, with heat and extrusion welding of all seams, attach-ing the liner to various structures, and performing field testing and quality control. Upon completion of the in-stallation, the liner system was com-pletely flooded as a final test for any previously undetected leaks.

The geomembrane-lined planter walls were finished with a rock facing treatment and the interiors covered with natural materials such as moss, lava rock and plantings to create a natural environment for the butterflies. The exhibit incorporates entrance and exit vestibules that create an air-lock effect to contain the butterflies within the exhibit. Curved semi-opaque exterior walls of the exhibit allow ample natu-ral light to filter in from the museum’s adjacent exterior windows. The “green-house” style walls also incorporate two clear observation panels that allow visi-tors to view the exhibit without paying a walk-through fee. However, these same curved walls and curved planter struc-tures further complicated the installa-tion process as the membrane was cut and seamed to fit as tight as possible.

The project’s success will ultimately be determined by the performance of the lining system, as it will be protect-ing the floors of the museum beneath the new, enlarged Butterfly House.

The installation was completed by Hallaton Inc. of Towson, Md. Hal-laton president, Todd Harman, said: “The Butterfly House project is very similar to the lining of a landfill or a petroleum tank farm, but instead of protecting groundwater from contami-nation, we are protecting the nation’s treasures from water damage.”

Charging for butterfliesIn a rare move, the Smithsonian an-nounced that it will charge an entry fee to patrons of the walk-through Butterfly Pavilion—an institutional first for a permanent exhibit.

The NMNH’s two-tier look at but-terflies includes a general exhibition that will focus on the evolution of plants and butterflies. It will include a window looking into a special pavil-ion filled with live tropical butterflies. All that will be free. But visitors who want to enter the Butterfly Pavilion, a

| Close-ups of the geomembrane and geomembrane seals and welds as the linersystem was installed this fall.




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Project Showcase

climate-controlled space with about 300 to 400 butterflies floating around, will have to pay a fee.

Butterfly pavilions are expensive ventures because the butterflies and plants have short life spans and need to be replaced frequently. The annual

operating cost is estimated at about $900,000. Construction of the com-plete butterfly exhibition house and pavilion totaled about $3 million.

The butterfly pavilion was designed by Smithsonian staff members to cre-ate a hospitable environment for the

insects. The butterflies will be drawn to light, with lamps substituting for natu-ral light. It is not clear how long each visitor will stay, because the 1,400-ft2 pavilion will be heated to 80 degrees with 80% humidity. Staff members estimate that 30 people at a time will be able to visit the smaller pavilion area, and they predict 200,000 visitors a year.

The Smithsonian is using farms in Latin America, Africa, Asia, and North America to supply the butterfly pupae.

Project Highlights“Butterfl ies & Plants: Partners in Evolution”Location: The Smithsonian

Institution’s National Museum of Natural History in Washington, D.C.

Geomembrane: Stevens Geomembranes

Distributor: Watersaver Co. Inc.

Installation: Hallaton Inc.

| Detail of the freshly poured concrete floor over the liner, and the lined knee-wall of one planter where it meets the wall and the vestibule.



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Using geosynthetics for avalanche protection in northern IcelandOne of the northernmost towns in Iceland, while pictur-esque, sits at the base of avalanche-prone mountainsides.

Tiny Siglufjördur—population about 1,400—has sought to have this situation addressed for years. But a final an-swer—a reinforced-soil avalanche-barrier system—was implemented only recently.

The beginnings of the latest earth-retention system was installed in 2005—a soil-stabilizing solution, and ideally, an avalanche protection barrier. It is the first time that this geocell product has been used for such an application.

Siglufjördur is on the northern coastline of Iceland, about 40km (25 miles) from the Arctic Circle on the Green-land Sea. The town is situated at the head of a fjord of the same name (Sigluffiord), surrounded by the 3,000-plus-ft. towering slopes of the Tröllaskagi mountain range.

Because of the location, Siglufjördur and the nearby mountains receive significant precipitation. Annual snow-falls totaling 40-60in. or more are common. And many years, residents have been evacuated for fear of damage from avalanches during winter months.

| Siglufjördur: The historic architecture, colorful rooftops of the upper town, the harbor, and the awe-inspiring panorama provide a photographic setting.

Photos courtesy of Presto Products Co.

Ron Bygness, editor of Geosynthetics, contributed to this article.

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| An earth-retention system is now in place as an avalanche protector near the municipality of Siglufjördur in northern Iceland. The town rests at the base of steep mountainsides that are covered with snow for much of the year. Five barrier systems, each more than 1 mile long and 15-20ft high, were used to create the avalanche protection barriers.

| Siglufjördur’s dwindling population still depends on the sea for work, and the village enjoys a dramatic setting beside a small fjord at the northern tip of the Tröllaskagi mountain range.


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Historically, avalanches have posed a threat to the people of Iceland. In 1995, 2 avalanches killed 34 people in Sudavik and Flateyri in the north-western Iceland region called West Fjords. Both communities are west of Siglufjördur.

The last deadly avalanche in Si-glufjördur occurred in 1919, when 18 people were killed. Since that time, frequent avalanches have caused ex-tensive property damage to the town. In an effort to ensure the safety of the residents of the village, Icelandic authorities took measures to protect Siglufjördur against the possibility of another deadly natural disaster.

VSO Consulting, an Iceland-based engineering design firm, selected the geocell earth-retention system for the

Installation criteria included: soil conditions, availability of backfill, budget, and aesthetics.



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avalanche barriers. “The plan was to use a concrete retaining wall, but then VSO decided to look for something more environmentally and aestheti-cally suited for the area, since the bar-rier would be located on the slopes facing houses in the village,” said Gary Bach, business unit manager for Presto Products Geosystems. “VSO found the product while searching the Internet … it met the criteria, plus it offers a long-term solution for deflecting snow away from the village.”

Among the key criteria for select-ing this type of installation were: soil conditions at selected sites, availability of suitable backfill materials, project economics, and the desired aesthetics of the completed site.

An initial portion of the avalanche-protection project was completed in December 2005. But additional barrier sets followed, including cur-rent construction that will continue through next year. All told, the proj-

ect involves the installation of 5 bar-rier sets, each more than a mile long and 15-20ft high.

“The system provides a sustainable solution to soil-stabilization prob-lems,” said Dan Senf, an engineer and director of business development for Alcoa Geosystems.

“Manufactured from polyethylene, the system’s outer cells, when filled with site topsoil, provided an ideal environment to support native vegeta-tion. In addition, the material is much faster to install than comparable earth-retention systems, such as concrete,” said Senf, who provided on-site con-struction start-up support.

The multi-layer design of the geo-cell material makes it adaptable and capable of meeting a wide range of ap-plications. The system has proven quite versatile, providing solutions to other earth-retention problems ranging from stabilizing roadway embankments to the construction of retaining walls.

Project HighlightsProtection structures against snow avalanches in northern Iceland

Clients: Icelandic Ministry for the Environment and the town of Siglufjördur

Expected completion: 2008-2009Location: Siglufjördur, IcelandObjective: avalanche protection

for the townConstruction manager: VSO Ltd.

Consulting Engineers, ReykjavikConstruction company:

Sudurverkl Ltd.Landscape architects: Landslag

(Reynir Vilhjalmsson), ReykjavikConsultants:

Thorsteinn Johannesson, Iceland Meteorological Offi ce

Geosynthetic materials: Geoweb by Presto Products Co.

The protection system’s outer walls, when filled with soil provided an environment to support native vegetation.



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New PU composite is expected to extend German North Sea defenses

The next step in a 3,000m2 extension of a North Sea shoreline erosion-control effort on islands off the northwestern coast of Germany included the installa-tion of more than 20 metric tons of a new polyurethane-mixture coating last summer.

The Elastocoast resin system, developed by BASF subsidiary Elastogran, is proceeding with shoreline protection projects in partnership with the Institute of Hydraulic Engineering (IHE), Hamburg-Harburg, Germany.

The most recent deployment was during July 2007 at Hallig Gröde, one of 10 German salt-marsh islands (see sidebar, page 23), part of the Frisian Archipelago that stretches just off the North Sea coastlines of Denmark, Germany, and the Netherlands. The porous, transparent PU coating was previously applied on shores of Hamburger Hallig and the historic island of Sylt (see sidebar, page 25).

Photos courtesy of BASF

| Since autumn 2005 a composite of crushed stones and polyurethanes provide erosion protection for a portion of the imperiled northern end of the island of Sylt. Pilot projects in the north of the island of Sylt: During the past 2 years, polyurethane/aggregate revetment layers have undergone trials at this particularly exposed coastal area, with success.




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“Elastomer revetments utilize the property of poly-urethanes by creating permanent and elastic bonds with stone surfaces,” explains Professor Erik Pasche of the IHE. “This creates sturdy, porous—but at the same time—very resistant revetments.”

Traditional coastal protection has usually used rigid “adhesive” materials such as concrete or asphalt to deflect wind-blown stormwater and erosive waves. But these have proven both costly to install and prone to rupture under severe conditions. This new elastomer system is a mixture of polyurethanes and a rock/stone aggregate laid on top of a stabilizing geomembrane.

The liquid, two-component, plastic polyurethane is stirred on-site, then mixed—for example, in a concrete mixer—with the crushed stone, which it envelops like a thin, transparent film. The finished mix of materials, which remains ready to use for about 20 minutes, can be applied in covering layers about 15-30cm (ca. 6-12in.) thick. The mixture even hardens underwater. Alternatively, it can also be sprayed onto a loose layer of stone ballast using a high-pressure technique.

The result is a highly stable, elastic, open-cell structure in-tended to absorb, rather than deflect, the energy of crashing waves and driving rain. The plastic bonds the broken stones to one another only at certain points, but elastically. In this way, it absorbs the energy of the insurgent volumes of water.

What are Halligs?The Halligs are a bizarre series of tiny islands in the North Sea, the largest of which is inhabited by 200 people. Life is tough on a Hallig—violent storms, gales, and flooding are routine events. The residents live in rustic-style homes, perched on man-made mounds designed to withstand the ele-ments.

The islands were created after the polar ice caps began to melt, causing a massive rise in sea levels all over the world. On the North Frisian coast of Germany, this completely flooded vast areas of mainland, leaving only a few areas above water. Centuries of fierce storms and the continual ebbing of the tides reduced these to mere sediment. But over time, they gradually developed into a series of salt marshes or mudbanks.

Once there were more than 100 islands. Today there are only 10.

| The structure of stone ballast: Reinforcing stone ballast with a porous stone structure (schematic diagram).




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PU composite

Nearly 500m2 of the new breakwa-ter technology, containing almost 7 MT of the elastic covering, has been placed on Hallig Gröde since last year and has proved effective, according to Elastogran.

The PU resin system, which contains 60% renewable, plant-derived polyol, claims to be an ecologically sound so-lution that has no harmful impact on aquatic life. Further, the PU/rock-envel-oped blanket can cut costs because of its relative ease of installation.

The installation process involves contouring the beach, placing a geo-membrane to prevent undermining by sand erosion, then capping with a 15-30cm-thick layer of the PU resin-and-rock combo. The coating begins to harden within 20 minutes, reaching maximum strength after 2 days.

Currently, about 800km of dike systems protect the German North Sea shoreline against the forces of nature. The North Sea coastal states

Schleswig-Holstein and Lower Saxony already invest almost €100 million (ca. $135 million U.S.) every year in coastal protection measures and for flood prevention.

The engineering principle of yield-ing slightly to the thundering volumes of water in order to contain them is the key. The same principle is applied in the construction of modern dike systems, which rise with a very gradual incline on the side facing the sea. This allows the breakers to gradually expend their force without causing damage, instead of explosively releasing their full forces upon immediate impact.

But the dikes also need a protective layer, considering the serious threats of erosion that are reaching dramatic proportions along exposed sections of coastline—as, for example, in Sylt (cited above). And in some cases, it is threat-ening the integrity of entire islands.

These efforts could increase even further in the future, as scientists pre-

dict that global warming will cause a rise in the sea level up to 70cm. Con-jecture regarding a rise in sea levels in coming decades could make effective coastal protection even more impor-tant throughout the world.

ConclusionThe idea of bonding stone ballast together using polyurethane plastics was first realized with successes in railbed stabilization. The stability and durability of these stone ballast embankments is now transferring to a maritime context.

Dike systems, such as those on Sylt or the Hamburger Hallig, are only one of many possible application sites for the polyurethane/crushed stone revet-ments. Along coastlines, they could also protect harbor installations, flood barrages, riverbank promenades, and banks of inland waterways.

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The ‘disappearing’ island of SyltLocated 20km (13 miles) west of the German/Danish border lies the island of Sylt.

The long, narrow island (pronounced Zoolt) is the northernmost point of Germany. Sylt lies in the North Sea off the coasts of Denmark and the German state Schleswig-Holstein. It is the largest island of the Frisian archipelago, which stretches through the North Sea from Denmark to the Netherlands.

Pounding North Sea storms seem to take more and more of the coastline each year. And some think that Sylt will one day disappear into the sea.

A disappearing playgroundScientists have warned that the western coast of

Sylt is one of the most fragile ecosystems in Europe and may one day be reclaimed by the sea. The entire island is little more than a strip, only 550m (1,800ft) wide at its narrowest point, which is composed mostly of sand and very little rock. As such, it presents little resistance—especially after it’s been stripped of its te-nacious salt grasses—to the onslaught of erosion and deterioration.

Although the winter months in general, and storms at any time of the year, are highly destructive, it’s dur-ing strong south winds that most erosion takes place, and on some mornings after violent storms, huge amounts of sand migrate from the beachfront out into the North Sea.

“Look, the wind, the rain, and the sea are taking my island from me,” said one local with a kind of despair. “The crashing tides are claiming our coast.”

If there is an air of desperation about the Germans who love and frolic in this North Sea playground, it may be because they know it won’t be here forever.



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Part 1

Three challenges in building SRWs and other reinforced-soil structuresBy Michael R. Simac, P. E., and Blaise J. Fitzpatrick, P. E.

IntroductionWhile segmental retaining walls (SRWs) have been rou-tinely used for more than 15 years now, there are still three challenging issues facing owners considering their use. What is the best way to procure, design, and then build these structures to minimize short-term problems and ensure long service life?

This three-part series will examine each of those issues, in an attempt to provide guidance for owners, designers and contractors that balances each of their prospective risks and rewards. Although these articles will focus specifically on SRWs, all the other reinforced soil structures (i.e., MSEWs, Reinforced Soil Slopes (RSSs, basket walls, etc.) face these same issues, such that the information presented is equally applicable.

Change-in-grade structures like SRWs have revolu-tionized land development strategies for residential, commercial, and industrial sites as every project attempts to maximize the usable land area. This quest for usable space has led to taller and longer SRWs, making the structures a more significant engineering, construction, and cost component to these projects. An owner’s deci-sions on how to procure, design, and construct SRWs is critical to the overall success of the project, due to the SRW’s importance to the project and, usually, the construction schedule.

The landowners/developers must understand the options and how their decisions on these three key challenges affect the quality, usefulness, and long-term performance of the structure. When the landowner/de-veloper is unaware of these options, it would benefit both the designer and installer to review these options with the owner/developer to agree on the best approach for the project. The objective is to have similar and rea-sonable expectations on SRW performance and how to best achieve it.

Without this discussion before the project, unrealis-tic expectations and/or poor performance can lead to serious disagreements on whose responsibility it was to ensure a better end result. This scenario is occurring often enough that professional liability insurance com-panies have begun red-flagging professionals practicing in retaining wall design.

This series presents our proactive options for addressing these challenges in ways that can benefit all stakeholders.

Part 1: Options for buying the SRW (October/November 2007 issue of Geosynthetics magazine)

Part 2: Options for designing the SRW (February/March 2008, Geosynthetics)

Part 3: Options for building the SRW (April/May 2008, Geosynthetics)

Part 1: How to contract for MSE walls1.1) Do-it-yourself (DIY) projectsUnless the landowner has specialized training and/or experi-ence in designing and constructing SRWs, this approach is usually limited to small homeowner projects. These projects are generally successful only when used for landscape defini-tion walls. SRWs that support driveways, patios, or extend to greater than 3-ft. in height, tend to be problematic. Therefore, in most situations the owner benefits from having professionals involved to design and construct the SRW.

1.2) Contractor-supplied designsThis is the most widely used approach to procure SRWs, allowing the contractor to supply the design (drawings,

calculations, and specifications) for the SRW to be built, based on limited information provided by the owner. This process starts with a general note on a grading plan indi-cating “wall design by others.” Sometimes there are speci-fications for approved wall systems, which rarely includes installation details or typical sections, and usually provides no guidance as to the design methodology or minimum design specifications.

Currently, the owner and site designer select this con-tracting approach in an effort to ensure competition among several proprietary SRW systems. There is significant mar-ketplace momentum from materials suppliers who encour-age and support this method, to foster business alliances with both wall contractors and SRW designers.


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Mike Simac is principal engineer at Earth Improvement Technologies Inc., based in Fort Mill, SC.

Blaise Fitzpatrick, Fitzpatrick Engineering Associates P.C., is based in Lawrenceville, Ga.



The material suppliers provide “preliminary designs” and/or “material quantity estimates” to the contractor for pricing to the owner. After the owner selects the SRW contractor, usually based on cost, the contractor commits to a material supplier, who in turn recommends or retains an SRW designer to produce a “final design” that includes construction drawings using only the material supplier’s products. In most cases, these construction drawings are sealed by a licensed professional, providing everyone some level of confidence.

This approach eliminates direct communication and a contractual relationship between the SRW designer and owner. The SRW designer is working in this method for the contractor, not the owner, and communication between the SRW designer and other design professionals (architect, civil engineer, and geotechnical engineer) is either limited or nonexistent. There is no contractual mechanism or means of communication that can resolve conflicts between various project design elements, and ultimately produce an SRW design that is totally integrated with the other project design elements.

Without owner-provided specifications and qualifica-tions, it is difficult to compare the various SRW contrac-tor proposals, other than price alone. Consequently, the most aggressive SRW design produces the lowest cost SRW to build. This aggressiveness may include: liberal soil strengths, optimistic loading conditions, and favorable groundwater conditions. Additionally, some proprietary design approaches are aggressive by eliminating or altering minimum standards-of-practice (e.g., facing connection, bearing capacity, internal failure surface orientation, and global stability).

This method tends to lead to confusion before, during, and after construction on exactly which party has engineer-ing responsibility (and liability) for important design deci-sions. Foremost among the confusions:

Has the site (civil) designer adequately addressed wall batter and surface water diversion around the SRW in establishing the site grading plan? Has the owner provided sufficient geotechnical informa-tion to perform the design? Who determines sufficiency and/or orders (and pays for) more testing?Has the site (civil) designer adequately addressed global stability for the grades being established? Is the site (civil) designer and owner expecting the SRW designer to per-form global stability?Has the site geotechnical engineer provided specific al-lowable foundation bearing pressures for the proposed SRWs? Without specific foundation recommendations, the SRW designer may just designate the required foun-dation pressure, leading to significant foundation correc-tion procedures that may negate the cost effectiveness of the entire SRW system.Who is responsible for defining the strength properties, locating a suitable borrow source with those properties, and ensuring that the reinforced (infill) soil is properly

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| The Greenville Southern Connector Tollway Authority accepted a contractor and material supplier design for the first-ever pile-supported integral bridge abutment wall constructed with geogrid reinforcement. Geosynthetic reinforcement resists lat-eral pressures from both the retained soil and deformed piles.

| Camp Creek Marketplace in Fulton County, Ga., provided stormwater retention within a 25-ft-high basket-faced MSEW that supported a 22-ft-tall SRW. Designs were produced by FEA using MSEW and ReSSA to account for global stability.


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compacted? Routinely, the SRW designer working for the contractor assigns that responsibility to the owner, a party whom the SRW designer has no authority to obligate, thus creating scenarios when the owner’s quality assurance testing professionals were unaware that those services were even needed.Who is responsible for ensuring that the correct materi-als are installed in a proper manner for the entire struc-ture? SRW installers should be responsible for their own quality control and document it. All too often, the only oversight is the owner’s paid quality assurance testing, which tends to be insufficient in scope. Who is responsible for surface water design above and around the SRW? This is particularly important after SRW construction. But it is also important prior to completion of all storm drainage improvements and final grading, when temporary sediment and erosion control plans can unduly induce surface water intru-sion not contemplated for final design.

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Reinforced soil structures

While the SRW designer is clearly responsible for all subsurface drainage design, the designer is also responsible for ensuring that site surface water does not enter the reinforced soil vol-ume. This is generally handled by a drainage swale, if not already included in the site (civil) drawings.

Alternatively, the site (civil) draw-ings may illustrate alternative means to channel water away from the SRW, such as a diversion berm or conven-tional curb and gutter for roadways or parking areas. In either case, the size and type of surface water di-version needs to be coordinated with

the site (civil) designer to ensure that it is adequate.

Although this method is the most popular, and the path of least resis-tance for the site designer or owner, it can suffer greatly if the SRW is not properly defined. The owner can use standard specifications available through professional organizations or from material suppliers, provided that the following items are defined, which enhance the effectiveness of this method of procurement:

Method of analysisMinimum design safety factors and material reduction factorsDefine the external/live loading conditionsAssign specific design responsibility for global stability and foundation supportA finalized site plan design with good surface water drainage designRequire a quality control testing program by the SRW installation contractorHave an independent third party provide a design review checkThis contractor-supplied method

also places design responsibilities on an SRW installation contractor who is neither equipped technically (by train-ing), legally (by registration), or finan-

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Photo courtesy of Wall Technologies Company

| A steeply sloping site was turned into North Point High School in Fulton County, Ga., using a vegetated face basket wall that negotiated changes in grade ranging in height from 15 to 60 ft. Designs were produced by FEA using MSEW and ReSSA to account for global stability.

| Site grading requirements for Augusta Crossing power center site in Augusta, Maine, called for a 50-ft.-tall SRW design that utilized rock fill crushed on-site and accounted for global stability influenced by a lake below. WallTek Design Build, Inc addressed those and other design issues, even modifying the cross-section to a reinforced soil slope where site geometry allowed.

Photo courtesy of WallTek Design Build Inc.


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cially (by insurance) to accept the risks associated with design liabilities.

The advantage for the SRW con-tractor is a stream of business projects found by material suppliers who appear to be willing to work out all the techni-cal details for little or no cost, in ex-change for a loyalty to their products.

Inevitably, each stakeholder’s desire to expand its business creates further burdens on capacity, eventually leading to both parties looking outside this ex-clusive, loyalty-based relationship. This burden on capacity affects the owner, relative to the effort level, and quality of the SRW installed on the site, par-ticularly regarding the SRW design.

1.3) Design-build approachThis is the method that the owner and site designer usually believe they are getting when option 1.2 (above)—

“Contractor-supplied design”—is specified in the project documents. There are several procedural, con-tractual, and legal criteria necessary in the project specifications to invoke a true “design-build” scenario. The following criteria generally are neces-sary for the owner to ensure that a design-build contract is in place:

• Design and construction is done by the same legal entity, licensed to provide and perform those combined services by the presiding governing authorities.

• Total design/engineering respon-sibilities and control are given con-tractually to the design-build contrac-tor. Responsibility for all aspects of engineering design include, but are not limited to: selection of materials, global stability, bearing capacity, and structural design and performance, including installation tolerances.

• Design-build contractor is respon-sible for all pre-engineering testing, data

collection, and quality control testing throughout the construction phase.

• Design-build contractor is re-sponsible for integration of the SRW design with other project design com-ponents, such as buildings, roadways, and utilities. Conflicts between design elements will be resolved by the de-sign-build contractor.

• The owner and design-build con-tractor agree on what defines the pro-posed SRW (i.e., plan location and change in grade) and the performance criteria for end-of-construction, and at the end of the agreed-upon per-formance period (i.e., 3, 10, 75, 125 years).

This approach is more easily inte-grated into a project when all other components are also procured via a “design-build” contract. However, with some care, it can be specified as a separate component in a conventional contract, with a pre-approved, experi-

| Developers of The Villas of St. Augustine Island, Fla., utilized design-build expertise to address the aesthetic features of the tranquil entrance lake and engineering issues generated by permanent and fluctuating inundation of the SRWs supporting a roadway.

Photo courtesy of Pinnacle Design Build



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That is how we want our company

In manufacturing our productsWith our clients

With the environmentTransparent like water

ence-based bidder’s list. Even with a pre-approved bidder’s list, the qualifi-cations for the design-builder should be listed in the contract documents, incorporating both experience and technical qualifications.

Finding qualified design-build con-tractors to ensure a competitive bid may be difficult. Currently, there are only a handful of companies nation-wide that can provide these services. And there may be only one or two local providers of similar services.

Design-build entities tend to more closely follow standards-of-practice for design and construction because they are equally responsible for both, and thus, are unable to deflect criticisms or deficiencies as the other party’s fault. Consequently, design-build SRW firms with succesful project experience will reveal a company record that can be trusted by owners.

Both the “Design-build” and the “Contractor-supplied design” ap-proaches allow for fair competition among various proprietary systems. Both of these approaches also have the added owner advantage of deferring the design costs to the construction stage.

1.4) Owner-provided designThis is the traditional method for al-most all building and site develop-ment contracts in North America. The SRW design is easily incorporated into the site design drawings. This can aid (and sometimes is required by) the prevailing plan approval process of the local jurisdiction. Routinely, the owner retains a site (civil) designer who establishes site grades, stormwater management, and utilities.

The SRW designer just becomes part of the owner’s design team, usu-ally through a subcontract with the site designer, such as how a structural en-gineer was retained when cast-in-place concrete retaining walls dominated the site development market.

The SRW designer develops design calculations, specifications, and draw-ings through direct communication with other members of the owner’s



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design team (i.e., architect, civil en-gineer, and geotechnical engineer). Issues related to geotechnical concerns and how the SRW is coordinated with the site grading can be addressed up front.

The key advantages of this approach are that the SRW design is integrated into the overall site design early in the site-planning process, providing the most cost-effective design alternatives, by adjusting all site design components to incorporate constraints that are in-terdependent on each other from all components, not just the SRW.

Geotechnical information required for SRW design can be obtained as part of the original site investigation, streamlining the geotechnical costs and design schedule for the SRW. The owner is assured that all retaining wall installation costs are based on the same design, formulated specifically for the site location and exact design requirements. This ensures a true in-stallation cost comparison, based on the same design.

| ECS Ltd. produced for the developer of a power center site in Lowesville, N.C., a reinforced soil (recycled concrete) basket wall and SRW design that eliminated excavation and replacement of 10-12ft of soft alluvial foundation soils, with extensive soil exploration and monitoring during construction. These walls, 10-39 feet tall, experienced large settlements (> 2’) prior to stabilizing and comple-tion of paving above, saving more than a half-million dollars in development costs.

Photo courtesy of ECS Ltd.Reinforced soil structures



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Brockton Equipment/ Spilldam, Inc.

SILTDAM Turbidity Control Curtains;designed, engineered and manufacturedto meet the demanding site requirementsof our customers.

Marine Construction &DemolitionDredging

RemediationErosion Control

Shoreline Revetment

Options include:• 6 in (150mm), 8 in (200mm) and 12 in

(300 mm) Floatation

• Permeable or Impermeable varieties

• Skirt depths from 3 ft (1m) to 75 ft (23m).

Turbidity Barriers Containment Booms

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EnvironmentalProtection Systems

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This can be accomplished by pre-senting the owner-provided design via two methods:Base Contract DesignThe SRW designer prepares a design with one unique set of SRW facing and geosynthetic reinforcement. All contractors are required to bid, install-ing the base contract design included in the project drawings.

A contractor can subsequently propose an alternative design using other SRW facings and geosynthetic reinforcement combinations as a value engineering proposal. The alternate design must be stamped by a differ-ent qualified design professional and approved by the original project SRW designer as an equivalent design.

Generally, equivalency will be based on: similar reinforcement strengths, vertical spacing, and length, particu-larly if global stability is controlling the reinforcement length, provided that all the required design safety factors are met using the same infill soil pa-rameters. This approach ensures that all SRW installation contractors are competing on the same design.

If direct competition on SRW ma-terials (facing and reinforcement) is desired, the owner may direct that a second unique design be placed in the project plans. When this is done, it is recommended that the contractor be required to declare in the bid proposal which system is to be built, so that the owner receives the best pricing at bid time, rather than the contractor obtaining it after the award.

Generic DesignThe SRW designer prepares one de-sign with a unique set of SRW fac-ing and geosynthetic reinforcement properties that are appropriate for a variety of interchangeable materi-als. Contractors are required to bid and install the SRW using any com-bination of the specified materials included in the project drawings.

The owner can select two or three SRW facings with similar overall di-mensions meeting their aesthetic ap-pearance requirements. The SRW designer then selects two or three geo-synthetic reinforcements for which the

design properties are roughly similar. The unique generic SRW design is then based on the lowest performance prop-erty in each category for each of the combinations.

Although this approach fails to obtain the optimized design for each component part, it produces a con-servative, cost-effective installation due to the cost competition created by interchangeable “generic” parts.

AdvantagesIronically, most of the contractor-sup-plied designs reviewed by the authors have been produced from the perspec-tive of the SRW designer working for the owner. Obviously, SRW designers prefer the tighter controls and require-ments that an owner-provided design places on the contractor.

The owner obtains much better con-trol of the finished product by having an SRW design with known risks, by integration with other design disci-plines, and creation of a quality as-surance program that ensures compli-ance of construction to the design. The owner also obtains fair and even cost competition on his design.

The contractor also knows he is competing fairly on the same design, now being judged on his ability to build, without exposing himself to any design liability.

The material suppliers benefit be-cause they can now compete solely on their ability to manufacture products, instead of how efficiently they can design SRWs, and can do so without any design liability.

DiscussionWhen SRWs entered the marketplace some 15-20 years ago, the owner and site (civil) designer were provid-ing retaining wall designs with the project plans, usually cast-in-place, cantilever concrete walls designed by a structural engineer. Owners, quite naturally, did not want to pay for two designs, so SRWs were sold with a contractor/vendor supplied design.

Shortly thereafter, when the eco-nomic advantages of SRWs became so compelling, owners and site designers


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just dropped the cast-in-place concrete wall design completely and specified SRWs, as “Retaining Wall-Design by Others.” This seemed to make sense be-cause the design appeared to be free.

But as we all know, nothing of value is ever really free, as the cost of the design was included in the materials or installation of the SRW. As cost competition moved from SRW vs. concrete wall, to SRW vs. SRW, de-sign costs, material costs, and costs to build a design became significant issues in the bidding competition. The successful low bidder was the one who could reduce those cost components the most.

This cost reduction trend was ini-tially welcomed by owners and devel-opers. However, as time progressed, performance problems with SRW installations have increased, causing concern among some of the largest land developers, leading them to place constraints on SRW use or to enact strict design and construction stan-dards, while still using the contractor-supplied design approach.

Some states, such as North Carolina, have passed building code amendments

| Ground Engineering Solutions produced a generic SRW design for the developer of this multi-use redevelopment site in downtown Greenville, S.C. The SRW design accounted for geotechnical data and global stability, and integrated with all the appurtenant struc-tures and utilities located above the SRW.




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requiring that retaining walls higher than 4ft be designed at the time of zoning/site approval, instead of at the building permit stage. This amendment requires owners to develop the designs up front, at the project planning stage, as was originally done for cast-in-place concrete walls. North Carolina closes the design and construction loop by requiring special inspection of SRWs, with a compliance letter at the end of construction by the SRW designer of record, ensuring that the SRW was built in accordance with the plans and specifications.

While all methods described above are workable and offer certain advan-tages, the owner-provided design rep-resents the best approach for all stake-holders to achieve the best performing SRW, long-term, at the lowest possible design and construction costs. Conse-quently, it appears to be time in the SRW marketplace maturation process for the owner to resume control of the design process. There are several key factors that support that approach:

Design methods are well established, with many qualified designers.There are many proprietary sys-tems, but their principles are the same.The age of the market means that many patents are close to expiration.There are numerous qualified SRW installers.Contractors are less willing to be conduits for design services and their liabilities.Design needs to be done in the owner’s best interest, with integra-tion between the various design disciplines involved.Design control will help to reduce the number of long-term perfor-mance problems.This examination of procurement

options provides owners, and their specifying site designers, with sufficient knowledge to select the approach that best matches their project objectives.

Although the authors believe that an owner-provided design is the best

•

•

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alternative in most situations, there are circumstances when other options are certainly appropriate. Choose wisely, because it affects the outcome of the project and SRW performance, more than you would initially believe.

Good luck.

References:Collin, J., et. al. (1997) “Design Manual

for Segmental Retaining Walls,” Na-tional Concrete Masonry Associa-tion, 2nd edition. Herndon, Va.

Elias, V.E., Christopher, B.R. and Berg, R.R. (2001) “Mechanically Stabi-lized Earth Walls and Reinforced Soil Slopes, Design and Construction Guidelines,” prepared for Federal Highway Administration, National Highway Institute, Contract No.: DTFH61-99-T-25041, 393 p

Elias, V.E. and Christopher, B.R. (1997) “Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, Design and Construction Guidelines,” pre-pared for Federal Highway Admin-istration, Demo 82, Contract No.: DTFH61-93-C-000145, 371 p

North Carolina Building Code 2002 (2002) Sections 1610 “Soil Lateral Load” adding 1610.3 “Defi nition of Retaining Systems” and making Section 1704 “Special Inspectors” mandatory; based on International Building Code 2002.

Part 2: Options for designing the SRW (February/March 2008,Geosynthetics)



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Testing produces design guidance | Follow this new anti-scour mat product through the testing process

By Michael D. Robeson

Michael D. Robeson, P.E., is the former manager of the Colorado State University Hydraulics Laboratory in Fort Collins. He is currently

technical services manager at Profile Products LLC.

AbstractA new product with the application of culvert and storm-water outlet scour protection was tested at Colorado State University. The objective of the testing was to determine the hydraulic and sediment stability threshold conditions. This article presents the engineering design guidance offered as a result.

IntroductionOutlet erosion protection of culverts can be a serious prob-lem due to the increased erosive potential of outlet flows. Determination of the scour potential should be common practice with the design of culverts.

Exit velocity can be considered the main factor in deter-mining the need for erosion protection at a culvert outlet. Culverts channelize flow resulting in outlet velocities that

Table 1 | Test Matrix for the Chamfered Mat

Confi guration Number (No.)

Nominal Description

Test Number (No.)

Driving Head(m / ft)

Discharge(m3/sec / ft3/s)

Culvert Exit Velocity(m/sec / ft/s)

Performance Threshold Exceeded? (Yes/No)

1 Sod/TM 1 0.67 / 2.20 0.56 / 19.7 2.56 / 8.40 No

1 Sod/TM 2 1.28 / 4.20 1.44 / 51.0 3.66 / 12.0 No

1 Sod/TM 3 2.32 / 7.60 2.56 / 90.3 4.88 / 16.0 No

2 HPTRM/TM 4 0.50 / 1.65 0.31 / 11.1 2.23 / 7.30 No

2 HPTRM/TM 5 0.81 / 2.65 0.78 / 27.5 2.80 / 9.2 Yes

2 HPTRM/TM 6 1.22 / 4.00 1.44 / 51.0 3.57 / 11.7 Yes

Table 2 | Test Matrix for the Unchamfered Mat

Confi guration Number (No.)

Nominal Description

Test Number (No.)

Driving Head(m / ft)

Discharge(m3/sec / ft3/s)

Culvert Exit Velocity(m/sec / ft/s)

Performance Threshold Exceeded? (Yes/No)

1 Sod/TM 1 0.67 / 2.20 0.56 / 19.7 2.56 / 8.40 No

1 Sod/TM 2 1.28 / 4.20 1.44 / 51.0 3.66 / 12.0 No

1 Sod/TM 3 2.32 / 7.60 2.56 / 90.3 4.88 / 16.0 No

2 HPTRM/TM 4 0.50 / 1.65 0.31 / 11.1 2.23 / 7.30 No

2 HPTRM/TM 5 0.81 / 2.65 0.78 / 27.5 2.80 / 9.2 No

2 HPTRM/TM 6 1.22 / 4.00 1.44 / 51.0 3.57 / 11.7 Yes

3 HPTRM/2X TM 7 1.25 / 4.10 1.42 / 50.0 3.57 / 11.7 No

3 HPTRM/2X TM 8 1.80 / 5.90 2.01 / 71.0 4.31 / 14.15 n/a

3 HPTRM/2X TM 9 1.81 / 5.95 2.02 / 71.3 4.33 / 14.20 Yes

4Flared End w/ HPTRM/TM 10 0.67 / 2.20 0.56 / 19.7 2.56 / 8.40 Yes

n/a – not available

Figure 1 | Photograph of the tested transition mat




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tions based upon reliable literature regarding permissible velocities of both vegetated and high-performance turf reinforcement mat (HPTRM)-lined channels. As a basis for comparison, Table 4 presents maximum permissible velocities for common materials. The permissible velocity provided for the unvegetated HPTRM was determined from prior CSU performance testing.

The data collected for each configuration were examined by CSU and hydraulic performance limits were determined for the tests conducted under the aforementioned test pro-gram. Subsequently, the data obtained from the vegetated test, Configuration No.1, proved to indicate the critical nature of vegetation with regard to increased performance levels and lower factors of risk. Given that the sod and mat combination had exceeded industry standards for permis-sible velocities, a combination of HPTRM and sod with the mat was not tested; however, the utilization of such

tend to be higher than the natural stream velocity, in which case flow adjustment or energy dissipation could be necessary to mitigate the potential for downstream chan-nel erosion. Culvert performance can be affected by the downstream water surface elevation or tailwater.

For this article, low tailwater conditions will be examined. Low tailwater conditions result when the flow exits at approximately one-third of the culvert (Stevens and Urbonas, 1996).

Two types of scour can occur in the vicin-ity of culvert outlets including local scour and general channel degradation. Local scour can be considered a direct result of the high-velocity flows at the culvert outlet while general channel degradation results from changes to the river regime by natural processes or human activities. This article will focus on the local scour that could occur at culvert outlets.

Test program summaryInformation presented within this article is intended to provide a brief summary of the test program, present an analysis of the data collected during testing, and present design guidance. During the summer of 2005, hy-draulic performance testing was conducted by Colorado State University (CSU) on the selected mat. A total of 10 tests were con-ducted under this program, which consisted of 4 configurations. Figure 1 is a photograph of the transition mat (TM) submitted for testing.

For this testing program, an 83.82cm (33-in.) diameter by 15.24m (50-ft) long culvert at the base of the steep gradient overtopping facility (SGOF) was utilized. An existing water-pipe network was used to deliver flow into a head box by means of an overhead diffuser to control varying levels of driving head at the invert of the culvert.

A test matrix was developed to summarize and present the details of the testing program. Tables 1 and 2 present the test matrices for the chamfered and unchamfered systems, respectively. More detailed information pertaining to the testing program can be found in the testing report (Clopper, Robeson and Thornton, 2005).

AnalysisTable 3 presents a summary matrix of the soil-loss analysis for each of the configurations tested under the described test program.

Data from the hydraulic testing of a full-scale scour coun-termeasure system can be used to determine the hydraulic performance threshold for each of the 4 test configurations since testing was started at reasonable performance projec-

Table 3 | Soil-loss Analysis Summary Matrix

Confi guration

Number

(No.)

Test

Number

(No.)

Average

CSLI

(cm.)

Average

CSLI

(in.)

Maximum

CSLI

(cm.)

Maximum

CSLI

(in.)

1 1 0.18 0.07 1.83 0.72

1 2 0.30 0.12 2.74 1.08

1 3 0.53 0.21 11.89 4.68

2 4 0.15 0.06 3.05 1.20

2 5 0.20 0.08 3.05 1.20

2 6 0.51 0.25 12.50 4.92

3 7 0.23 0.09 1.02 0.40

3 9 0.36 0.14 2.74 1.08

4 10 0.61 0.24 3.05 1.20

Table 4 | Permissible Velocities for Common Channel Materials

Channel Slope(percent) Material

Permissible Velocity(m/s) (ft/s)

0-1 Firm Loam 1.07 3.50

0-1 Kentucky Blue Grass 1.52 5.00

0-1 Bermuda Grass 1.83 6.00

0-1 Unvegetated HPTRM 2.00 5.50

0-1 15.25-cm (6-in.) Riprap* 2.40 8.45

0-1 30.50-cm (12-in.) Riprap* 2.35 10.65

*For the riprap calculations, a critical velocity equation from HEC-18 (Richardson and

Davis, 2001) was used with a representative depth for testing of 0.23m (0.75ft).




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Testing

a further analysis of the erosion that was observed for each configuration were plotted as contours. Based on these contours, the minimum length of protection for each test was deter-mined. Table 6 presents a summary of the results obtained from the contour analysis of the erosion for each test.

Design guidanceDesign guidance for riprap scour pro-tection downstream of a culvert out-let under low tailwater conditions can be found in Urbonas and Stevens, 1996. Subsequent sections provide de-sign guidance for the TM during low tailwater conditions. For culvert pipe outlets, low tailwater can be definedwhen: yt ≤ 3

where: yt = depth of tailwater at design flow (m,ft);

D = the diameter of a circular pipe (m,ft).

The first step in design of scour pro-tection at an outlet of a culvert regard-less of the material used for protection is to find the depth and velocity at the outlet. Pipe-full flow can be found using the Manning equation and the pipe-full velocity can be found using the continuity equation as follows:

where: Qfull = Pipe-full discharge (cms,cfs);

n = Manning roughness coefficient for the pipe-full depth ();

Afull = Cross-sectional area of the pipe (m2,ft2);

Rfull = Hydraulic radius for a pipe flowing full (m,ft);

Sf = Slope of the energy grade line, usually taken as the slope of the pipe (m/m,ft/ft).

Vfull = Qfull / Afull

where: Vfull = Cross-sectional average velocity of pipe-full flow (m/s,ft/s).

For flow conditions other than full-pipe flow, Figure 3 can be used to de-termine the flow depth and velocity. Using a known design discharge, Q, and the calculated pipe-full discharge, Qfull, calculate a discharge percentage as:

%Q = Q/Qfull where: %Q = discharge percentage

(%);

Table 5 | Relative Performance for Each Tested Configuration

Channel Slope

(percent)

Base Material

Confi guration Number

(No.)

Permissible Velocity of Base Material and Transition Mat

Velocity Increase

Ratio(No.)(m/s) (ft/s)0-1 Kentucky Blue Grass 1 4.88 16.0 3.20-1 Unvegetated HPTRM 2 2.80 9.2 1.40-1 Unvegetated HPTRM 3 3.57 11.7 1.80-1 Unvegetated HPTRM 4 3.57 11.7 1.8

Table 6 | Scour Contour Analysis Summary

Test Number(No.)

Confi guration Type

Velocity(m/s)/(ft/s)

Discharge(m3/s)/(ft3/s)

Required Length(m)/(ft)

1 A & B 2.56 / 8.4 0.56 / 19.7 1.22 / 4.02 A & B 3.66 /12.0 1.44 / 51.0 3.35 / 11.03 A & B 4.88 / 16.0 2.56 / 90.3 3.35 / 11.04 C & D 2.23 / 7.30 0.31 / 11.1 1.83 / 6.05 C & D 2.80 / 9.2 0.78 / 27.5 3.96 / 13.06 C & D 3.57 / 11.7 1.44 / 51.0 4.57 / 15.07 C & D 3.57 / 11.7 1.42 / 50.0 4.57 / 15.09 C & D 4.33 / 14.20 2.02 / 71.3 5.49 / 18.0

Figure 2 | Double layer of transition mat at culvert pipe outlet

a HPTRM over the sod should lead to the same, if not increased, perfor-mance levels.

By examining each of the tested configurations, a quantitative value of relative performance can be deter-mined from the information obtained during testing and Table 4. Table 5 presents the relative performance for each of the tested configurations.

By examining the velocity increase ratio from Table 5, it can be concluded that the TM can withstand 3.2 times more velocity than Kentucky bluegrass alone. In addition, for either Configura-tions No. 3 or No. 4, the TM can with-

stand 1.8 times more velocity than the unvegetated HPTRM alone.

It was also noted that Configu-rations No. 1, No. 3, and No. 4, all exceeded the permissible velocity for riprap up to 30.5 cm (12 in.), and Con-figuration No. 2 exceeded the permis-sible velocity for riprap up to 15.25 cm (6 in.). It should be noted that Config-urations No. 2, No. 3, and No. 4 were tested in an unvegetated condition. Once these HPTRM and mat systems become vegetated, an increased perfor-mance threshold can be expected.

To determine the appropriate amount of mat that would be needed for a variety of hydraulic conditions,

D

1.486 (U.S. Customary) or 1 (SI)

n

AfullRfull2/3Sf

1/2Qfull =




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Q = design discharge (cms, cfs).Utilize Figure 3 at the abscissa with

the value of %Q and continue up the chart until the discharge curve is reached. Read across to the ordinate to find depth of flow as a percentage, %D. Calculate the flow depth at the end of the pipe as:

d = D(%D)where: d = flow depth of the

design discharge at the end of the culvert (m,ft);

%D = flow depth percentage (%).Next, utilize Figure 3 at the ordi-

nate with the value of %D, and follow across until the velocity curve is inter-sected. Drop down to the abscissa to determine the velocity as a percentage, %V. Calculate the design discharge flow velocity at the end of the pipe:

v = V(%V)where: v = velocity of the design

flow at the end of the pipe (m/s,ft/s);%V = velocity percentage (%).Once the hydraulic conditions have

been calculated as outlined above, the coverage length of the TM can be determined from Figure 4 using the known exit velocity and type of installation desired. Figure 4 presents the hydraulic performance data for each installation type and conservative design curves which include each data point resulting from testing.

TM can be installed over sod (Type A), over sod covered by a TRM (Type B), over bare soil covered by a TRM (Type C), or over bare soil covered with a HPTRM (Type D)1.

These guidelines provide for the minimum recommended required coverage length to utilize. From the calculated design exit velocity, utilize Figure 4 to obtain the correspond-ing minimum transition mat coverage length (LTM) for installation types A and B or C and D. Then calculate the width of the transition mat:

WTM = 4D where: WTM = width of the transi-

tion mat (m,ft);D = diameter of culvert pipe (m,ft).

1 For installation types C and D, the minimum permissible velocity for the TRM or HPTRM is 1.67m/s (5.5 ft/s) for unvegetated conditions.


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It should be noted that for some in-stallations, a smaller width of TM may be acceptable; please consult with manu-facturers for guidance regarding smaller widths. It is important to note that the design curves presented in Figure 4 are dependent on culvert pipe size. For instal-lation types A and B, the design curve can be considered valid only for a maximum pipe diameter of 152.4cm (60 in.) and a maximum exit velocity of 4.88 m/s (16 ft/s).

For installation types C and D, the de-sign curve is considered valid for a maxi-mum pipe diameter of 152.4cm (60 in.) and a maximum exit velocity of 4.27m/s (14 ft/s), as shown in Table 7 (right). It should be noted that during testing at CSU, an 83.82cm (33-in.), pipe was utilized for most of the testing. During one test, a flared cul-vert pipe end was tested with an exit width of 152.4cm (60 in.). The data obtained from the flared end test provided the basis for al-lowing design up to 152.4cm (60 in.) as long as the velocity limits were maintained.

Additional design considerationsAdditional design considerations are

listed below as well as a design example providing a sample problem and associ-ated calculations as a reference.

• To maintain consistency with the test program it is recommended that the transition mats be placed beginning at the pipe outlet, preferably in contact with the pipe and centered laterally with the pipe, as shown in Figure 1. It is recommended that the transition mat be installed on a smooth and uniform grade.

• During testing, it was observed that an additional layer of TM installed for Types C & D just at the culvert outlet, as shown in Figure 2, improved erosion protection. The double layer was observed to minimize the open area of the system and was placed such that the open area of the second layer was offset from the open area associated with the first layer.

• If applicable, it is recommended that either a type A or B installation be used. If conditions do not permit the efficient establishment of vegetation, a type C or D installation utilizing a TRM which can withstand 1.67 m/s (5.5 ft/s) of velocity in unvegetated conditions should be used.

• The TMs do not dissipate energy. Therefore, it has been concluded that the

Hydraulic Elements of Channel Sections

Figure 3 | Values of hydraulic elements of circular section for various depths of flow

Hydraulic Elements (% of Value for Full Section)

Figure 4 | Coverage Length vs. Exit Velocity for Installation type

Exit Velocity (ft/s)

0 2 4 6 8 10 12 14 16 18

20

18

16

14

12

10

8

6

4

2

0

Types C & DTypes A & BTypes C & D CSUTypes A &B CSU

0 10 20 30 40 50 60 70 80 90 100 110 120

100

90

80

70

60

50

40

30

20

10

0

Wet

ted

Perim

eter

Area

Discharge

Hydraulic Radius

Velocity

Dep

th o

f Flo

w (%

)C

over

age

Leng

th (f

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transition from TM to the existing channel requires further examination and proper design to adequately deal with any remaining velocity and shear forces.

• Testing at Colorado State Univer-sity was conducted for an average angle between the discharge slope and the downstream angle of approximately 180 degrees.

Design exampleGiven: Pipe DiameterD = 81.28 cm (32 in.)LongitudinalPipe Slope S0 = 0.040 m/s (ft/ft)Pipe Manning Roughness n = 0.020

Step 1: Verify that this method is applicable.

D ≤ 152.4 cm (60 in.), Type A, B, C & D: OK

Step 2: Calculate the full-pipe dis-charge.

Qfull = 1.79 cms (63.34 cfs) from the Manning equation.

Step 3: Calculate the full-pipe ve-locity;

Vfull = 3.46 m/s (11.34 ft/s) from the Continuity equation.

Step 4: The highest exit velocities for a circular pipe are associated with a depth of approximately 83% the pipe diameter. This corresponds to an exit velocity of approximately 122% the full-pipe exit velocity. Thus, the design exit velocity is:

Vdesign = 4.22 m/s (13.84 ft/s)

Step 5: Verify that the design velocity from Step 4 is within the ac-ceptable range.

Vdesign ≤ 4.88 m/s (16 ft/s), Type A & B: OK

Vdesign ≤ 4.27 m/s (14 ft/s), Type C & D: OK

Step 6: Determine the necessary transition mat lengths based on in-stallation type.

A&B LTM = 4.88m (16 ft)

C&D LTM = 6.10m (20 ft)

Step 7: Calculate the necessary transition mat width (not a function of installation type).

WTM = 3.66m (12 ft)

ReferencesNorman, Jerome M., Houghtalen,

Robert J., and Johnston, William J. (2001). Hydraulic Design of Highway Culverts. Hydraulic Design Series No. 5 (HDS-5), U.S. Federal High-way Administration, Publication No. FHWA-NHI-01-020.

Norman, Jerome M., Houghtalen, Robert J., and Johnston, William J. (2001). Hydraulic Design of Highway Culverts. Hydraulic Design Series No. 5 (HDS-5), U.S. Federal High-way Administration, Publication No. FHWA-NHI-01-020.

Richardson, E.V., Simons, D.B, and La-gasse, P.F. (2001). River Engineering for Highway Encroachments: High-

ways in the River Environment. Hy-draulic Design Series No. 6 (HDS-6), U.S. Federal Highway Administration, Publication No. FHWA-NHI-01-004.

Richardson, E.V., and Davis, S.R., 2001. “Evaluating Scour at Bridges – Fourth Edition,” Hydraulic Engi-neering Circular No. 18, U.S. Federal Highway Administration, Publication No. FHWA-NHI-01-001

Schall, James D., Richardson, E.V., and Morris, Johnny L. (2001). Introduc-tion to Highway Hydraulics. Hydrau-lic Design Series No. 4 (HDS-4), U.S. Federal Highway Administration, Publication No. FHWA-NHI-01-019.

Stevens, Michael A., and Urbonas, Ben. Design of Low Tailwater Riprap Basins for Storm Sewer Pipe Out-lets. Urban Drainage & Flood Control District. 1996.

Project HighlightsTest subject: ScourStop Transition

Mat™ by Erosion Tech Inc.Testing by: Colorado State

University Hydraulics LaboratoryTesting performed in: 2005

Table 7 | Design curve contraints according to installation type

Installation Type Maximum Pipe Diameter Maximum Exit VelocityA&B 152.4 cm (60 in.) 4.88 m/s (16 ft/s)C&D 152.4 cm (60 in.) 4.27 m/s (14 ft/s)



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GEO news and notes from around the world

ASTM geosynthetics committees developing a host of proposed new standards

Three subcommittees of ASTM International Com-mittee D35 on Geosynthetics are currently developing several proposed new standards. The topics covered in the

following proposed standards are geosynthetic clay liners, geomem-branes, and the development of a mechanistic-empirical design guide for pavements.

Committee D35 will meet Jan. 30-Feb. 1, 2008, at the January

Committee Week in Tampa, Fla. All interested parties are invited to join in the standards developing activi-ties of D35. For membership or meeting information, contact Christine Sierk, manager, Technical Committee Operations, ASTM International (phone: 610 832 9728; [email protected]).Subcommittee D35.04 on Geosynthetic Clay Liners

Responding to shrinkage issues involving geosynthetic clay liners, Subcommittee D35.04 has launched work on a proposed new standard, WK12239, Test Method for Linear Dimensional Changes of Restrained Geosynthetic Clay Liners Under Cyclic Temperature and Hydration Conditions. WK12239 is an index test that covers the measurement of changes in linear dimensions of a geo-synthetic clay liner that result from exposure to changes in temperature and moisture conditions over time.

“The proposed standard will be used to evaluate prod-uct specific and project specific potential shrinkage for GCLs exposed to changes in moisture and temperature conditions,” said Richard Erickson, D35.04 member and senior engineer, Vector Engineering, Inc. “Potential shrinkage can then be utilized by designers and con-struction quality assurance monitors in compensating specified GCL overlaps to allow for anticipated GCL panel shrinkage.”

Erickson said Subcommittee D35.04 would like to expand the circle of participants involved in the develop-ment of WK12239. All interested parties, particularly those from the design and construction quality control/as-surance areas, are invited to join in the ongoing develop-ment of WK12239.

For further technical information, contact Richard Erickson, Vector Engineering, Inc., Grass Valley, Calif. (phone: 530 272 2448; [email protected]).Subcommittee D35.10 on Geomembranes

Subcommittee D35.10 is currently developing two proposed new standards, WK14305, Specification for Non-Reinforced PVC (polyvinyl chloride) Geomembrane

Seams, and WK14311, Guide for the Installation of Non-Reinforced Polyvinyl Chloride (PVC) Geomembranes.

According to Mark Wolschon, engineers, specification writers, users, suppliers, manufacturers, fabricators and installers of PVC geomembranes will be able to work with WK14305 hand-in-hand with D 7176, Specification for Non-Reinforced Polyvinyl Chloride (PVC) Geomem-branes Used in Buried Applications, in the design and construction of commercial, municipal and residential projects. “Typical projects using PVC geomembrane are landfills, wastewater lagoons, retention ponds, and deco-rative ponds,” Wolschon said.

A lack of industry consensus on how geomembrane installations should be done in the field is the impetus behind WK14311. This proposed guide would be used in conjunction with other specifications to offer engineers and contractors a reference regarding the typical condi-tions and minimum standard that they should expect from their PVC geomembrane supplier and installer.

“We would like to see more participation by the rest of the PVC geomembrane industry,” Wolschon said. “We will also need to conduct round robin testing of many of the re-cent specifications, including D 7176, Specification for PVC Geomembrane Material, and D 7177, Specification for Air Channel Testing of PVC Geomembrane Field Seams.”

For further technical information, contact Mark Wolschon, Environmental Protection Inc., Mancelona, Mich. (phone: 800 655 4637; [email protected]).Subcommittee D35.01 on Mechanical Properties

There is currently a national movement to develop a mechanistic-empirical design guide for pavements. This initiative requires that the fundamental material proper-ties for all components of the design be quantified. Sub-committee D35.01 is working toward this goal with the development of two proposed new standards, WK14361, Test Method for Determining Small-Strain Tensile Prop-erties of Geogrids and Geotextiles by In-Air Cyclic Ten-sion Tests, and WK14362, Test Method for Measuring Geosynthetic-Soil Interface Shear Modulus.

“These proposed standards will eventually be used to determine geosynthetic material properties that will be directly utilized in the design of geosynthetic-reinforced pavements when the geosynthetics are used as reinforce-ment of the base layer,” said Eli Cuelho, research engineer with the Western Transportation Institute and a member of D35.01. The most likely users of the proposed stan-dards are commercial testing laboratories that will run the tests for manufacturers and designers.

For further technical information, contact Eli Cuelho, Western Transportation Institute, Montana State Uni-versity, Bozeman, Mont. (phone: 406 994 7886; [email protected]).

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Industry analysts offer plastics predictions for the Middle EastWith relatively inexpensive raw materials at hand,

manufacturers in the Middle East could place themselves among the world’s leading plastics producers within a few years, according to industry analysts.

By the end of the decade, suppliers based in the Middle East could control about 20% of the world’s polyethylene (PE) production (compared to 1% in 1980) and 11% of the world’s polypropylene (PP) output (which wasn’t even a footnote in 1980 stats).

This evaluation was provided by Horst Maack, presi-dent of plastics consultancy MBS (Au, Switzerland), who spoke at the Dubai Plast Pro 2007 conference. Total capacity of Middle Eastern-produced thermoplastics (in-cluding PE, PP, vinyl, polystyrene, and polyester) is 7% today but in three years will reach 11%, he predicted.

One leading plastics supplier, Sabic, based in Riyadh, Saudi Arabia, has had limited competition in the region for years. But it is now facing new, privately financed competitors, including Tasnee/Sahara, Sipchem, APPC, and ventures with both Dow Chemical, and Japan’s Sumitomo and Saudi Aramco, Sabic’s primary supplier. That move did not sit well with Sabic, according to in-dustry sources.

One consultant speculated that despite the current row between the two, both Saudi companies might nonethe-less put their differences aside for a potential merger to protect existing markets. Husain noted that investments that previously—prior to the Sept. 11 attacks and the attempt by Dubai Ports to acquire U.S. harbor inter-ests—would have come from U.S. entities, are now being invested in new, local plastics producing operations.

Several Middle Eastern processors at the conference said the threat of low-cost imports from Asia is forcing them to target more value-added applications. Dubai-based film processor Nova Industries offered a warning about a price drop coming as early as 2008.

Another company that produces 3-layer, 8m-wide blown-film geomembranes said it envisions a big mar-ket for this material, given a growing market for local groundwater reservoir projects, landfills, and mining heaps for the new phosphate, sulfate, and gold industries in Saudi Arabia. Previously, all geomembranes had to be imported. Arno Johansen, an application marketing manager at Austria-based Borealis, a polyolefins and thermosets producer, said geomembrane demand in the region is growing at 6% per year.

Statement of Ownership



To: GMA Techline

Subject: Geotextile for base stability

I am a landscape architect and value your

Geosynthetics publication in my practice.

While reading the June/July issue [and the

article on] roads and housing on wet soils,

a current project challenge of mine came to

light: How to best provide base stability to

a proposed bituminous asphalt tennis court

through the use of geotextiles?

Further, can a geotextile be used to provide

base stability, longevity, and possibly reduce

costs, such as gravel fill?

StevenRhode Island

| Geosynthetic Institute |

GMA Techline Q-and-A

| More questions and answers from the GMA Techline:

AASHTO specs, cushion design, wrinkles, and thickness recommendations


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| Robert M. Koerner,GSI and the GMA Techline

Dear Steve,Geotextiles are regularly used to provide separation, stabilization, and/or reinforcement

to paved surfaces such as asphalt on a stone base course, as in a tennis court. The differences in the three functions that I just cited depend on the quality of the soil subgrade beneath the stone base course.

Separation (using a lightweight geotextile) is used for firm subgrades. Stabilization (using intermediate-weight geotextiles) is used for moderate subgrades. Reinforcement (using heavy geotextiles) is used for weak subgrades.

Fortunately, AASHTO (the organization of state highway departments) has specifications for separation and stabilization. Reinforcement requires a site-specific design.

As for your last question, geotextiles can be used to reduce base coarse thicknesses. There are many design charts available, but the ones I know are for roads … use these charts and be conservative.

GMA Techline

TECHLINE| The Geosynthetic Materials Association (GMA) offers the

GMA Techline, a resource for technical questions about

geosynthetics. E-mail: [email protected] for fast,

free, direct answers to your technical questions. GMA

serves as the central resource for information regarding

geosynthetics and provides a forum for consistent and

accurate information to increase the acceptance, and to

promote the correct use, of geosynthetics.





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Dear Lora,I recommended 600-900mm thickness based on heavy waste transfer trucks going into the landfill and the dynamic loads that they impose. If you can limit the weight (wheel loads) and control the truck drivers somewhat, you could probably use the 600mm value. I don’t see the thickness being less than this value. We have investigated two failures of liner systems being damaged under very thin cover soils over the liner system.

Regarding the use of crushed stone, my thoughts go to the type of leachate collection soil, and we are indeed using crushed stone for this application. If you are using coarse sand or fine gravel, go ahead and use it on the haul road as well, (i.e., match whatever soil you are using in the facility).Lastly, do provide for drainage of water coming down the side slopes. We have also seen two washouts of haul roads in this situation. If you are using gravel, it will probably take care of itself. If you use finer soils, you might even need a pipe in the system.Good luck.

GMA Techline

To: GMA TechlineSubject: Access roads on HDPE liners

I am designing a temporary waste storage facility that will be lined with a 1.5mm HDPE liner.

The facility requires access roads for the life of the facility—18 months. The access roads will be installed directly above the liner (1.5mm HDPE) and protective geotextile.

I’ve looked in “Designing with Geo-synthetics” (R. Koerner), which recom-mends 600-900mm of crushed stone for the road base. Given the life span of the facility (18 months), do you think it would be possible to reduce the depth of stone using other geosyn-thetic materials?

LoraAustralia

To: GMA Techline

Subject: Geomembrane wrinkles during installation

What is the general state of practice for limiting wrinkles

during geomembrane installation? What is the maximum

wrinkle height that should be allowed? Should it be trapped

straight up or allowed to fold over? Thanks.

ErnestNew York

Dear Ernest,Years ago, I thought that small wrin-

kles would flatten out when overbur-den was applied. Unfortunately, they do not. Even wrinkles as small as 14mm do not disappear under very large normal stresses. I’ll post a paper on the subject to you in this regard.

The bottom line is that the geomem-brane must be flat against the subgrade when it is backfilled.

GMA Techline

To: GMA TechlineSubject: Geotextile cushion design

Using the geotextile cushion calculator on landfilldesign.com, and according to your research report, we should be using a factor of safety of 3 for cushion geotextile and the size of the protrusion height at half the height of the largest particle of gravel used for the Linear Containment Remedia-tion System (LCRS).

The one question we are still puzzled about is the MFA for arching of solids. The [report] seems to suggest that arching may not be proportionally more effective for “deep” gravel.

Based on that, we used a shallow MFA of 0.75 rather than a deep MFA of 0.50. The LCRS gravel is 12in. and there are 3ft of operations layer made from sandy material for a total height of aggregate material that could arch 4ft.

The problem is, if we use an MFA of 0.75, then we need a 14.7 oz geotextile for 0.75in. gravel. If we use an MFA of 0.50, then a 10oz geotextile is sufficient for 0.75in. rock

What is the correct MFA for 4ft of aggregate above a geo-textile cushion?

MarkCalifornia

Dear Mark,Thanks for the question, however it is really beyond the lab experiments that we performed. That is, the extension from the truncated cones that were used to real soils/gravels are best-esti-mate values. I have done work on angularity and thought those MFs were OK. But the arching MF values are not as well-founded.

In the end, you seem to be in a decision between a 10osy and a 14.7osy nonwoven geotextile. The difference in cost is so small that I would use the larger value, and then you would have to specify a 16osy geotextile, which is the closest value typi-cally manufacturedGMA Techline




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Hi Dimitris,

Thanks for your question. To my knowledge, poly-

propylene is extremely resistant to the entire range

of pH-values, from acidic to alkaline. Thus, cement,

concrete, and shotcrete (with high values of pH) pose

no detrimental challenge to PP-geotextiles.

This cannot be said for polyester (PET) geotextiles,

but there are very few of these fabrics in current use.

I do not know the details of the LSO method that

you cite, but any immersion under high temperature

can be configured to develop a testing method.

GMA Techline

To: GMA TechlineSubject: Effects of temperature on geomembrane strength

I am working on the design for some lined res-ervoirs where the liner may be exposed for some time during the summer, with the temperatures possibly approaching 120°F. We plan to use a 60-mil HDPE geomembrane.

Giroud et al. advises that summer and winter temperature effects should be considered in the anchorage design. However, I have been unable to find data regarding changes of strength with temperature.

Can you direct me to where I might obtain this information, or perhaps advise on how these fac-tors are normally considered during design?

Also, do you know if the strength of white geomembrane is less affected by heat than that of black geomembrane?

GregCalifornia

Hi Greg,There have been undocumented studies on the temperature

dependence of HDPE GMs insofar as their stress vs. strain

response is concerned. In general, the higher the temperature,

the longer the elongation at break and the lower the strength.

The yield point, however, is relatively unaffected.

This is important in your question since we generally de-

sign HDPE on the basis of its yield properties. This being the

case, I do not know how it would affect an anchorage design.

At least in my example in “Designing with Geosynthetics,” it

would have no effect.

Thanks for the question and good luck.

GMA Techline

Geo08_FP.indd 1 7/27/07 10:56:52 AM

Ingrid,Technically, each polymer has advantages

and disadvantages. In the past, there was a great

deal of controversy on the subject. Currently,

however, polypropylene fibers (hence, geotex-

tiles) have essentially taken over the geotextile

market. One can hardly buy PET geotextiles in

the U.S. today. The reasons are lower resin costs

and lower specific gravity, thus you get greater

coverage per unit area of PP geotextile.

We can provide more technical details, but,

practically, the geotextile market is one of PP-

resin fibers.GMA Techline

To: GMA TechlineSubject: Polymer questionI would like to know if you can tell me which polymer is better to make nonwoven geotextiles, polyester or polypropylene? My problem is that I have to choose between two geotextiles with the same properties but with different polymers.Ingrid

Honduras

To: GMA TechlineSubject: Geotextile compatibilityIs there any lab testing method or norm verifying

the compatibility between polypropylene nonwoven geotextiles and shotcrete or concrete?

Is ISO 12960 relevant?My question derives from my need to prove

compatibility between this geotextile and material in contact in this project, such as shotcrete and a PVC membrane, and also with lean concrete and the PVC membrane.

DimitrisGreece



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To: GMA TechlineSubject: HDPE weldsFor HDPE geomembranes,

I am looking for information on what effect there might be, if any, on the integrity of a fu-sion weld when an extrusion weld is placed directly on top of it. This condition exists when completing patches at T-inter-sections, but there may be an occasion when an additional section of liner has to be welded directly on top of a fusion weld for greater distance.

Does the reheating of the fu-sion seam area caused by the extrusion weld cause any dete-rioration in the fusion weld? If so, to what extent?

BradCanada

To: GMA Techline

Subject: Landfill liner installation inspections

I was hoping that maybe you would have information on

training or certification on the inspection of installations of

geomembrane liners for landfills.

Thanks,DanielNew York

Dear Daniel,We have the exact program you are look-

ing for. It is called the Inspectors Certi-fication Program, and it is administered through our Geosynthetics Certification Institute. The acronym is GCI-ICP. You can look it up on our Web site: www.geosyn-thetic-institute.org. Please ask if you have more questions.

GMA Techline

Hi Brad and a very nice

question,

The concern is that the ad-

ditional heating by the extru-

sion welding would decrease

the molecular weight and have

a degrading effect on the mate-

rial at this sensitive location.

I have data (by Fred Struve)

showing that the molecular

weight curves of a single melt-

ing and a double melting lie

right on top of one another.

Send your fax number to

me and I will send the curves.

That said, there appears to be

no problem in this regard.

GMA Techline



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Geosynthetics O

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ber 2007

TenCate Geosynthetics develops and produces materials

that increase performance, reduce costs, and enable peo-

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TO: GMA TechlineSubject: Gas diffusion coefficients

I am in the process of evaluat-ing the mass flux of a gas moving through a 30-mil PVC geomem-brane. I am working with volatile organic compounds in soils.

What I need are typical values based on unsaturated soil vapors. I have found information on aque-ous liquids but not on unsaturated soil vapors.

Can you provide any assistance in finding typical gas diffusion co-efficients through geomembranes?

DavidIllinois

David,

Henry Haxo of Metrocon

evaluated solvent vapor dif-

fusion—as opposed to water

vapor diffusion— many years

ago. His data is in my book,

“Designing with Geosynthet-

ics.” The test is ASTM E96,

which is difficult to perform

using thick polymer geomem-

branes but is nonetheless do-

able. The French have a more

elaborate “pouch test” but it

is very tedious and expensive

to run.Regarding unsaturated soil

vapors, there is nothing. I sus-

pect that you could commis-

sion a lab to do the tests, but I

have never seen such data.

GMA Techline

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].




http://www.mirafi.com


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| Calendar |

16-18 OctoberWasteCon 2007Reno, Nev.

This three-day show will combine an extensive technical program with sessions about pertinent issues fac-ing the industry, SWANA’s training courses, an expansive exhibition floor, and networking events.

Event location: Reno-Sparks Con-vention Center, Reno, Nev.

Contact information: SWANA, 1100 Wayne Ave., Silver Spring, MD 20910; Phone: 800 467 9262; Fax: 301 589 7068; E-mail: [email protected].

21-24 OctoberOttawaGeo2007:The Diamond Jubilee ConferenceOttawa, Ontario, Canada

The Canadian Geotechnical Society (CGS), and the Canadian National Chapter of the International Associa-tion of Hydrogeologists (IAH-CNC) are the hosts for the 60th Canadian Geotechnical Conference & 8th Joint CGS/CNC Groundwater Conference.

The conference will be held at the Ottawa Westin Hotel Oct. 21-24. The conference theme “Breaking Ground in the Nation’s Capital” reflects this annual conference’s continued tradi-tion of providing a forum for recent research developments and advance-ments in geotechnical engineering and hydrogeology.

In addition to the technical pro-gram and plenary sessions, the con-ference will include local tours, work-shops, and short courses.

Contact information: Gibson Group Association Management, 8828 Pigott Rd., Richmond, BC V7A 2C4, Canada; Phone: 604 241 1297; Fax: 604 241 1399; E-mail: [email protected].

23–24 October10th International ThermoplasticElastomers ConferenceCologne, Germany

TPE-2007 will showcase new mate-rials, performance, and processing. To

register or for more information: +44 0 1939 250383; [email protected].

29 October–2 NovemberPrinceton Groundwater Inc.Remediation CourseOrlando, Fla.

“The Remediation Course” in-cludes topics such as: heterogeneous geohydrology; remediation technolo-gies, strategies, and designs; computer simulation; and aquifer, source, and plume characterization. The empha-sis is on acquiring working knowl-edge of the concepts, principles, and professional engineering practices of groundwater remediation.

Satisfactory completion will allow students to qualify for 3.8 continuing education units (CEUs).

To register or for more information: www.princeton-groundwater.com.

26-28 NovemberWaterproof Membranes 2007Cologne, Germany

Featuring trends and technical developments in the international industry, and organized by Applied Market Information Ltd., this event will be held at the Maritim Hotel in Cologne.

For Waterproof Membranes 2007, the focus is on construction and civil engineering applications such as roofing membranes and geomem-branes. On the first evening there will be registration and a cocktail reception, followed by a 2-day pro-gram of expert presentations

Waterproof Membranes 2007 will provide an international forum for all companies involved in waterproofing membranes to learn about the latest developments in materials, technol-ogy, applications, and market trends.

For further information, please con-tact Matt Wherlock, [email protected]; Tel: +44(0) 117 924 9442.

28-30 November2nd International Geo-ChangshaConference Changsha, China

This conference is focusing on new developments in geotechnical and geoenvironmental engineering, rock mechanics, and engineering geology.

Sponsoring organizations: Central South University (China) and Chinese Society for Rock Mechanics and En-gineering (CSRME).

Organizers: Central South Univer-sity (China), Changsha University of Science & Technology (China), Hunan University (China), and Hunan Uni-versity of Technology (China).

To register or for more information: [email protected]

13-17 JanuaryTransportation Research Board-2008Washington, D.C.

Plan now to attend the TRB’s 87th Annual Meeting, an information-packed program that will attract ap-proximately 10,000 transportation professionals from around the world to Washington, D.C., Jan. 13–17.

The TRB Annual Meeting pro-gram covers all transportation modes, with more than 3,000 presentations in nearly 600 sessions addressing topics of interest to all attendees—policy makers, administrators, practitioners, researchers, and representatives of government, industry, and academic institutions. The spotlight theme for 2008 is “Partnerships for Progress in Transportation.”

To register or for more information: www.TRB.org.

23-26 JanuaryMechanically Stabilized Earth Walls and Reinforced Soil SlopesUniversity of Delaware

This course emphasizes MSE walls and reinforced slopes, now including LRFD and allowable stress wall design sections (based on AASHTO LRFD Specifications, 4th Edition, 2007).





http://www.princeton-groundwater.com





http://www.TRB.org


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Upon completion, 2.8 CEUs or 28 professional development hours are awarded for full participation.

The first two days of the course (Jan. 23-24) provide most of the con-tent formerly covered in the previ-ous MSEW&RSS courses, including hands-on training in the use of ReSSA software. That course has been ex-panded now to incorporate the ma-terial covered over the next 1.5 days (Jan. 25-26), where the concentration will be on ASD and LRFD design of MSE walls, including hands-on train-ing in the use of MSEW software.

If you have already taken the En-gineering Outreach 2.5-day course (“MSEW&RSS”) but need to learn how the new AASHTO LRFD speci-fications apply to mechanically stabi-lized earth walls, you may register for just the LRFD module (Jan. 25-26).

For more information: UD-College of Engineering, 102 DuPont Hall,

Newark, DE, 19716; phone 302 831 2401; fax 302 831 8179; www.engr.udel.edu/outreach/short-courses/msew-rss/index.html.

18-21 FebruaryIECA’s Environmental Connection 2008Orlando

Environmental Connection—the world’s largest soil and water event—will run 18-21 February, with the Expo Feb. 19-21, at the Coronado Springs Resort in Orlando

Environmental Connection, IECA’s annual conference and expo, is your connection to the erosion and sedi-ment control industry, including qual-ity education events and a 3-day expo. The expo floor is a great place to see the latest in erosion and sediment con-trol products and technologies.

EC’08 also includes: • 20 full-day training courses address-

ing topics such as wind erosion, con-struction site management, and NPDES regulations and compliance. PHDs and CEUs are available.

• more than 50 case studies and technical paper presentations pro-viding original research and proven techniques to help you stay ahead in a competitive market.

• attendees to network with for in-creased exposure, business opportuni-ties and resources.

To register, exhibit, or for more in-formation:

• Exhibitor information, contact Kate Nowak at [email protected]; 800 455 4322 ext.15 (+1 970 879 3010 out-side the U.S.)

• To register, please view the con-ference Web pages at www.ieca.org; [email protected]; or call 880 455 4322 (+1 970 879 3010 outside the U.S.).

Is your company serious about the North American marketplace? Join the trade association with the most influence in geosynthetics in North America.

GeosyntheticMaterialsAssociation

For more information please contact us:Phone: +1 651 225 6907 or 800 636 5042 E-mail: [email protected] • Web: www.gmanow.com

GMA is dedicated to our members' success.GMA actively identifies, assesses, analyzes and acts upon market growth opportunities and issues that affect its member companies. The activities of the association are proactive in nature and center on five areas: • Business development

• Education • Government relations • Geosynthetics industry

recognition • Engineering support



http://www.engr


http://www.ieca.org




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| Calendar |

| Marketplace || For more information on classifi ed advertising in IFAI’s Geosynthetics, contact Shelly Arman at IFAI, 1801 County Rd. B W., Roseville, MN 55113-4061 USA Phone: 800 225 4324, fax: +1 651 225 6966 , e-mail: [email protected].

Help Wanted

EXPERIENCED GEOSYNTHETIC SALESPERSON NEEDED

We are a large, well established, nationwide geosynthetic distributor with a broad product line. We are seeking a new addition to our sales staff. You should be experienced in selling specialty geosynthetic materials and engineering solutions to engineers, owners and general contractors. You should have a strong technical background and technical /engineering degree. You should be able to operate independently and have an existing base of contacts. Travel is estimated at 30%, location and territory are negotiable.

All replies and communication will be in the strictest confidence. Please reply with your resume and salary requirements to:

IFAI, 1801 County Road B WBox 436, Roseville, MN 55113Or e-mail [email protected]

9-12 MarchGeoCongress 2008: The Challenge of Sustainability in the GeoenvironmentNew Orleans

The annual Congress of the Geo-In-stitute of the American Society of Civil Engineers (ASCE) will be held at the Sheraton New Orleans March 9-12.

The Congress will be alive with dis-cussions of current trends on the role of geoengineers and geoscientists in protecting and preserving the envi-ronment, and will also highlight the expansive and interdisciplinary nature of geoenvironmental issues.

This conference builds on the very successful 1995 ASCE Geoenvironment conference hosted in the very same city which is now flourishing with new growth and lively renewed spirit.

Practitioners, consultants, regula-tors, policymaker, researchers, educa-tors, and students will have numerous opportunities to learn about innovative and emerging scientific advances and

technologies that are needed to ad-dress a wide range of geoenvironmen-tal issues such as soil and groundwater protection and remediation and the challenges associated with sustainable development and mitigation of natural and man-made hazards.

GeoCongress 2008 will include all of the activities you’ve come to expect from the Geo-Institute’s annual con-ference: dozens of technical sessions, notable plenary lectures, relevant short courses, the Terzaghi, Peck, and Seed Lectures, hands-on workshops in all fields along with exhibits and networking events.

To register, exhibit, or for more in-formation: www.asce.org.

30 March-2 April23rd International Conference on Solid Waste Technology and ManagementPhiladelphia

Participants are expected from more than 40 countries: researchers, educators,

government officials, consultants, man-agers, community leaders, and others with an interest in solid waste are invited to submit papers for oral presentation or poster session at this conference.

Papers related to all aspects of solid-waste technology and management are of interest, including: landfill top-ics, municipal waste sites, mining and mineral wastes, research topics, con-taminated and industrial wastes, case studies, innovative technologies, geo-technical topics, environmental impacts, and liners, caps, gas and leachate.

The deadline for submission of ab-stracts is Oct. 31.

Venue: Radisson Warwick Hotel, Philadelphia; host contact: Widener University (“The Journal of Solid Waste Technology and Management”), Ronald Mersky, 1 University Place, Chester, PA 19013-5792; phone: +1 610 499 4042; fax: +1 610 499 4059; e-mail: [email protected].

Ordering reprints of an article that featured your company in Geosythetics is an excellent way to maximize

your company’s exposure to the marketplace. These inexpensive tools can be used in:

Maximize your company’s exposure!

• Promotional Materials• Sales Literature• Professional Training• Business Development• Media Kits

To order customized article reprints, contact Russell Grimes at

800 385 9402 or +1 651 225 6968 or e-mail [email protected].

Electronic article reprints Ideal to post on your Web site or use as a promotional tool in e-mails.

Hard copy article reprintsCustomized to meet your company’s marketing needs.

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2–5 March 2008 GeoAmericas 2008 Hilton Cancún Golf & Spa Resort Cancún, Mexico

“The first Pan-American Geo-synthetics Conference and Exhibi-tion” will provide a forum for geo-synthetics engineers, practitioners, and academics to explore current and potential applications for geo-synthetics, while concurrently of-fering an active marketplace for the promotion of geosynthetic prod-ucts, applications, and services to users throughout the Americas.

Program highlights Although final program development is still under way

attendees can expect: • more than 300 papers presented during 34 technical

sessions: • special journal sessions • life’s work sessions • 10 1.5-hour Spanish-language training lectures • 12 1.5-hour English-language training lectures • 8 full-day short courses • a closing evening reception with entertainment• for more details: www.geoamericas.info

Hotel highlights • beachfront location on the Caribbean Sea • 4 restaurants and dining clubs • programmed activities for the entire family • 18 hole, par 72 golf course • full-service fitness, salon, and spa • the beauty and splendor of the Yucatan at its doorstep,

including Mayan ruins, the island of Cozumel, tropical lagoons, and more

Exhibits The 3-day exhibition will be held 3–5 March 2008

offering an excellent opportunity for geosynthetics manufacturers and service providers to present new technologies and innovations to regulators, contractors, engineers, specifiers, and other geosynthetics users from both hemispheres of the Americas. Please contact Sarah Hyland, Sales Director: [email protected].

Language English is the official language of the conference.

Technical papers from both hemispheres will be pre-sented in the technical sessions and provisions are in

place to ensure that session leaders will be able to address questions and answers in Spanish and/or Portuguese. In addition, short courses and training lectures may be of-fered in English and/or Spanish.

For your calendar Session Leaders, Authors and Speakers:

1 October 2007: Review of first draft papers due15 November 2007: Final papers due1 December 2007: Final acceptance of papers due

Call for Student Competition Abstracts coming soon.For Organizers of Training Lectures:

15 October 2007: First version of training lecture presentation due

30 November 2007: Organizers notified of comments on first version of presentation

31 January 2008: Final version of Training Lecture Presentation due

For All Attendees:1 December 2007: Early Bird Deadline. Book by 1

December to receive lowest registration ratesTravel and housing information now available. Hotel

rooms are limited, book early.GRI-21

GeoAmericas programs open with a full day of short courses on 2 March, followed by 3 days of technical ses-sions, training lectures, and exhibits. GeoAmericas 2008 will also serve as host for the annual GSI Conference (GRI-21).

Member discounts Members of IGS, IFAI-GMA, and IGS chapters

receive discounts on registration and exhibits.

Conference location Hilton Cancún Golf & Spa Resort, Boulevard Ku-

kulcan Km 17, Zona Hotelera, Cancún, Quintana Roo, Mexico, 77500; Phone +52 998 881 8000; Fax +52 998 881 8080; www.hiltoncancun.com.

Hotel reservations and group room rates at the Hilton Cancún are available now for GeoAmericas 2008: www. geoamericas.info.

Registration information Registration for GeoAmericas 2008 is available now:

www.geoamericas.info.Registration for the full conference includes registra-

tion for GRI-21.

For more information Please contact Beth Wistrcill, Manager of Geo-

synthetics Conferences and Events: +1 651 225 6956; [email protected].





http://www.hiltoncancun.com






Geosynthetics O

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55

| Advertisers Index |

| 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. For advertising rates and

information call Sarah Hyland at 800/319-3349

www.geosyntheticsmagazine.info

| The Geosynthetic Materials Association is directed by the needs of the North American geosynthetics industry. It serves as thecentral resource for information regarding geosynthetics and provides a forum for consistent and accurate information to increase theacceptance and to promote the correct use of geosynthetics. Visit www.gmanow.com, Contact: Andrew Aho [email protected], 800 636 5042.

ACE Geosynthetics Enterprise Co. Ltd.877 522 3436www.geoace.com . . . . . . . . . . . . . . . . . . .5 GMA Member

Agru America800 373 AGRUwww.agruamerica.com . . . . . . . . . . . . Cv2GMA Member

American Wick Drain Corporation800 242 WICKwww.americanwick.com . . . . . . . . . . . . .31

Atarfil S.L.+34 958 43 92 00www.atarfil.com . . . . . . . . . . . . . . . . . . .31

Brockton Equipment/Spilldam Inc.800 699 2374www.spilldam.com . . . . . . . . . . . . . . . . .33

Canadian Road Builders(ASP Testing & Engineering)+1 780 960 1690www.coletanche.com . . . . . . . . . . . . . . .24

CETCO 800 527 9948www.cetco.com . . . . . . . . . . . . . . . . . . . .32GMA Member

Contech Earth Stabilization Solutions, Inc.800 338 1122www.contechess.com . . . . . . . . . . . . . . .15GMA Member

DEMTECH Services Inc888 324 9353www.demtech.com . . . . . . . . . . . . . . . . . 11

Fiberweb, PLC800 321 6271www.typargeotextiles.com . . . . . . . . . . .21GMA Member

Firestone Specialty Products Co.800 428 4442www.firestonesp.com/ifai1 . . . . . . . . . . .48 GMA Member

Huesker, Inc.800 942 9418www.hueskerinc.com . . . . . . . . . . . . . . .19GMA Member

Layfield Geosynthetics888 225 4436www.geosyntheticbarriers.com . . . . . . .35GMA Member

Leister Process Technologies800 694 1472www.leister.com . . . . . . . . . . . . . . . . . . .41

LG Chem America Inc.+1 847 231 6107www.lgchem.com . . . . . . . . . . . . . . . . . . .7GMA Member

Maccaferri Inc.800 638 7744www.maccaferri-usa.com . . . . . . . . . . . .25GMA Member NAUE GmbH & Co. KG+1 49 5743 41-0www.naue.com . . . . . . . . . . . . . . . . . . . .10

Propex800 621 1273www.geotextile.com/ad . . . . . . . . . . . Cv4 GMA Member

Raven Industries Inc800 635 3456www.rufco.com . . . . . . . . . . . . . . . . . . . .29GMA Member

Samyang Co. Ltd.+82 02 740 7784www.samyang.com . . . . . . . . . . . . . . . . . .3

SKAPS Industries+1 706 354 3700www.skaps.com . . . . . . . . . . . . . . . . . . . .39 GMA Member

SRW Products800 752 9326www.srwproducts.com . . . . . . . . . . . . . . .5

Strata Systems Inc.800 680 7750www.geogrid.com . . . . . . . . . . . . . . . . . . .1GMA Member

Tenax Corp.800 356 8495www.tenax.com . . . . . . . . . . . . . . . . . . . .34GMA Member

TenCate Geosynthetics800 685 9990www.mirafi.com . . . . . . . . . . . . . . . . . . .49GMA Member

Trelleborg Building Systems AB+1 46 370 481 00www.trelleborg.com . . . . . . . . . . . . . . . .14

Watersaver Co. Inc.800 525 2424www.watersaver.com . . . . . . . . . . . . . . .39






http://www.geoace.com

http://www.agruamerica.com

http://www.americanwick.com

http://www.atarfil.com

http://www.spilldam.com

http://www.coletanche.com

http://www.cetco.com

http://www.contechess.com

http://www.demtech.com

http://www.typargeotextiles.com

http://www.firestonesp.com/ifai1

http://www.hueskerinc.com

http://www.geosyntheticbarriers.com

http://www.leister.com

http://www.lgchem.com

http://www.maccaferri-usa.com

http://www.naue.com

http://www.geotextile.com/ad

http://www.rufco.com

http://www.samyang.com

http://www.skaps.com

http://www.srwproducts.com

http://www.geogrid.com

http://www.tenax.com

http://www.mirafi.com

http://www.trelleborg.com

http://www.watersaver.com




Geo

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ACROSS

1. Former GMA Executive Council Chairman, Joe

3. Geosynthetic solution on a golf course? (2 words)

11. Polite address

12. VP at Tenax, ____ Zhao

13. It’s being used to create the next generation of functional fabrics

15. Rejection

17. Current GMA Exec Council Chairman works here

21. Type of material

23. Hole __ __ ! (2 words)

25. Execute

26. Goes underground, in a way

27. Terrain

28. See 59 across

29. What investors want to see

30. Was placed

32. Houston lining company

34. Formerly an oersted

36. ___acetylene

38. Containers

41. Type of material

44. Stick in

46. HDPE or LLDPE?

48. Location indicator

51. Polyolefin’s prize

54. Geosynethics expert, R. Kerry ____

57. Outlet ____

59. Reliable guy (goes with 28 across)

60. Freeze up

61. Wetlands bird

63. Professor at NCSU, Mohammed

64. Enviro ____

DOWN

1. UT-Dallas prez is a ____ expert

2. ___- threatening

3. Excel chart

4. “The Lord of the Rings” bad guy

5. Comedian, Aykroyd

Geosynthetics Crosswordby Myles Mellor

6. King of the jungle

7. Eskimo dwelling

8. New

9. 46 across description perhaps (2 words)

10. Move forward

11. Rock, in a way

14. Popular

16. __ a good conference!

17. Works at Washington State DOT, ___ Allen

18. Complete

19. Excited

20. On the cutting ___

22. Protection

24. Indian curry companion

26. Bruce Lee symbol

31. Vegas event

33. Propex purchased them in 2006

34. Festivals

35. Observe

37. Sweet potato

39. Geosynthetic industry consultant, ___ Berg

40. Weight measure, for short

42. Temperature measure

43. Another weight measure, abbr.

45. Gravitic forces

47. Just before

49. Nero-wear

50. Marshlands

52. Geosynthetics expert, ___ Ko-erner

53. Roman 51

55. White paper, for short

56. Slippery creature

57. ATM number

58. Golf goal

62. “Fearless” star, Jet __

Answers to the crossword can be found at http://www.ifai.com/Geo/crosswordanswers.cfm

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http://www.ifai.com/Geo/crosswordanswers.cfm

The Membership Advantage

Business ConnectionsMembers network through IFAI to maximize their business

potential. Members also access cost-saving business services.

Industry NewsMembers get current specialty fabrics information through

our seven niche publications and daily news updates on the

IFAI Web site.

Reach your customersMembers receive free listings in the Review Buyer’s Guide,

the “Yellow Pages” of specialty fabrics industry. This reference

tool is used by thousands of buyers throughout the year.

Members receive discounts on IFAI Expo, the largest specialty

fabrics trade show in the Americas.

Members receive advertising discounts in our seven magazines

Your First SourceMembers contact Information Central Hotline to fi nd

sources for supply and participate in our member-to-member

referral program.

For more information, contact Kathy Mattson,

Director of Membership, +1 651 225 6942,

[email protected].

www.ifai.com

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Documents

Geosynthetics, October 2007, Digital Edition - ifaijapan.comifaijapan.com/secure/2007Geo/1007GS_DigitalEditionul.pdf · Integral studs for high capacity drainage capability Geotextile