GeosyntheticsMagazine.com | May 15, 2012

A new publication, ASTM Standards on Erosion and Sediment Control Technology: 3rd Edition, features 76 of the latest ASTM specifications, test methods, practices, and guides for minimizing soil erosion and controlling sediment delivery to lakes, streams, and other bodies of water.

A May 14 press release from ASTM described the book as “a vital resource for designers, specifiers, landscape architects, developers, resource managers, excavation contractors, landscapers, site inspectors, and permit enforcement personnel.”

The ASTM standards featured in the publication address erosion and sedimentation processes caused by wind, rain, flowing water, and wave attack, and cover manufactured products and natural materials, according to the release. Manufactured products include mulches and tackifiers, biodegradable blankets, turf reinforcement mats, sediment retention and filtration devices, gabions, grout-filled mats, geotextiles, and articulating concrete block systems.

ASTM Standards on Erosion and Sediment Control Technology: 3rd Edition, is available for $249 in print (450 pages; 8.5 x 11, soft cover; ISBN: 978-0-8031-7031-5; Stock #: EROSION12).

To purchase ASTM publications, search by stock number on the ASTM website, or contact ASTM customer relations (phone: 877-909-ASTM, sales@astm.org).

ASTM staff contact: Marsha Firman: 610-832-9612, mfirman@astm.org

GeosyntheticsMagazine.com | May 11, 2012

A $10,000 fellowship from the Geosynthetic Institute (GSI) is helping to fund a University of Kansas School of Engineering graduate student’s research on improving the safety and stability of underground pipelines.

Ryan Corey, a Topeka native and doctoral student in civil engineering with an emphasis in geotechnical engineering, received the one-year GSI fellowship for the 2011-2012 academic year. GSI fellowships totaling $60,000 were awarded to eight students from a worldwide pool of applicants (see table below).

The funding allows Corey to continue his research on geosynthetics. “Geosynthetics are a great way to reduce overall costs on a project,” Corey said. “One example is road construction. Geosynthetics can provide extra strength and durability, so instead of laying pavement that’s, say, 10 inches thick, a company can use 8 inches and save money on materials. Plus, geosynthetics add to the overall lifetime of the road.”

Corey’s research focuses specifically on protecting pipelines that carry hazardous or valuable material, such as oil or natural. According to the Pipeline and Hazardous Materials Safety Administration, between 1992 and 2011 in the United States, there were more than 10,000 significant pipe incidents that resulted in more than 350 fatalities, 1,500 injuries, and $5.3 billion dollars of property damage.

“I’m working to find the best ways to reduce the stress and strain on a flexible pipe and the soil that surrounds it caused by stationary or mobile forces on the surface.” Corey said. “This fellowship certainly provides an opportunity of a validation of my research, and that’s great. This is an area that needs more attention. It’s my hope that this will promote the future use of geosynthetics in an area where they are not being used a lot right now.”

Corey said that even though including geosynthetics at the outset of a project adds to the initial costs, there are bound to be savings in the long-term. “The additional safety, stability, and durability provided by this material far outweigh the initial price tag on a project.” Corey said.

Corey earned his undergraduate degree in civil engineering from Kansas State University in 1994. He received his master’s degree in civil engineering from KU in 2008 and hopes to finish the work on his doctorate by May 2013. He conducts his research in the group of Dr. Jie Han, professor of civil, environmental and architectural engineering.

GSI fellowship status for 2011-2012 academic year

SOURCES University of Kansas, Geosynthetic Institute

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

GeosyntheticsMagazine.com | May 11, 2012

By Jessica Bies

Under hoof at the 2012 Del Mar Grand Prix national horse show this year, a geotextile horse footing designed to enhance riding performance and also to protect the legs of the equine participants improved jumping conditions for several Olympic hopefuls.

A combination of sand and shredded geotextiles or elastic fibers, geotextile footing is used in horse arenas to reduce dust and help with water drainage. The geotextile fibers stabilize the sand particles, helping achieve higher slide strength and intermediate shear resistance. Not only does the footing resist compacting, but it provides elasticity and bounce that helps protect horse sinews and joints while reducing risk of injury. Different ratios of geotextile and sand are used to create footings well-suited for a variety of conditions and can be used to create arena floors for competition or for training paddocks.

Geotextile footing is often installed on top of a flooring grid. The grid system disperses the weight of the horse or stock over a larger surface area and separates the footing from the ground sub-base, insuring that they do not mix. It also enhances drainage and prevents settling that could result in an uneven surface.

Geotextile footing has been used to increase traction and cushion competing horse at the FEI World Cup, the FTI Winter Equestrian Festival, and the 2010 Alltech FEI World Equestrian Games.

Jessica Bies is a Geosynthetics magazine intern.

GeosyntheticsMagazine.com | May 10, 2012

Melody A. Adams has joined Parametrix as a senior engineer in the company’ Portland, Ore., office. Adams, a member of Geosynthetics magazine’s Editorial Advisory Committee since 2000, was most recently a senior project manager at Shaw Environmental. Parametrix is an engineering, planning, and environmental firm, with nine office locations in the western U.S.

GeosyntheticsMagazine.com | May 9, 2012

Illinois-based Profile Products announced in a May 8 press release the hiring of Adam Popenhagen as regional market development manager. His territory will include North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Wisconsin, Michigan, Iowa, Illinois, Indiana, and Kentucky, the release said.

Popenhagen was previously with the Minnesota Department of Transportation as a stormwater specialist in the agency’s Office of Environmental Stewardship. He holds CPESC, CPSWQ, and CESSWI certifications, and will be based in western Wisconsin.

Source: Profile Products

GeosyntheticsMagazine.com | May 3, 2012

With hydraulic fracturing, or “fracking”—the use of high-pressure water to help extract previously inaccessible shale gas—eager to replicate its success outside the U.S., the market for water treatment will grow nine-fold to $9 billion by 2020. This expansion will spur technology innovation and novel thinking about water disposal and reuse, but the field is rapidly growing overcrowded, creating significant risk for new entrants, Lux Research said in a May 1 press release.

The release noted that fracking requires between 4,000m³ and more than 22,000m³ of water per well, producing toxin-laced brine that can be more than six times as salty as seawater. Its growth has energized the water industry, inspiring a bumper crop of new water-treatment startups vying to treat the highly challenging flowback water.

“Fracking represents a significant water-treatment challenge—hydrocarbons, heavy metals, scalants, microbes, and salts in produced and flowback water from shale gas wells represent a water treatment challenge on par with the most difficult industrial wastewaters,” said Brent Giles, a Lux research analyst and the lead author of a report titled, “Risk and reward in the frack water market.”

“While the opportunity is large, only a few companies are really positioned to profit. Meanwhile, nearly every start-up we talk to is going after frack water, regardless of their technology, and many of them are going to come to grief,” Giles added.

Robert Koerner, director of the Geosynthetic Institute (GSI), has noted that “Geosynthetic materials are playing key roles for fracking pit containment, underdrain management, soil separation, rainwater harvesting, dewatering,” and other similar applications.

GSI has written a white paper on the subject: “Geosynthetic opportunities with shale gas extraction.”

Source: Lux Research Inc.

GeosyntheticsMagazine.com | May 2, 2012

To support continued North American and international growth, the Layfield Group of Companies announced in a May 1 press release new capital expansion plans for its Vancouver, B.C., and Edmonton, AB, operations.

The Vancouver expansion includes the addition of a new blown-film extrusion line, adding 24 million pounds (10.9 million kg) of new capacity and facility upgrades, according to the release. This expansion will provide new capacity for Layfield’s core product lines of geomembranes, construction films, and specialty packaging products. Completion is expected by September 2012, the release said.

The Edmonton expansion includes a 12-acre site, 125,000-square-foot (11,600 m²) office, distribution, and production facility. The expanded production capacity will be designed for converting geomembranes, geosynthetics, and industrial fabrics using new welding and sewing technologies, according to the release. Construction of this new facility is currently under way with a completion date of January 2013.

Source: Layfield Group

GeosyntheticsMagazine.com | May 1, 2012

Propex announced in an April 30 press release an expansion of its product portfolio with the addition of GRIDPRO™ biaxial and uniaxial geogrids. Made in the U.S., the new geogrids are manufactured to meet all industry specifications and are now ready to ship from the company’s Ringgold, Ga. facility, the release said.

“The addition…builds on our brand promise to deliver the most complete portfolio of products to the industry,” said Ralph Bruno, Propex’s executive vice president of sales and marketing. “We are committed to providing the highest quality of domestic-made products that meet or exceed industry standards.”

The release also noted that Chattanooga-based Propex offers a full line of geosynthetic products through its network of distributors, from woven and nonwoven geotextiles to erosion control products and, now, geogrids.

Source: Propex

GeosyntheticsMagazine.com | April 30, 2012

A new bridge that incorporates geosynthetic-reinforced soil (GRS) technology is in the works in Barton, Md., southwest of Cumberland, in the western part of the state.

The bridge over Moores Run on Potomac Hollow Road will cost about $800,000, most of that total covered by a grant from the Federal Highway Administration’s Innovative Bridge Research and Deployment Program. That program includes prefabricated bridge elements and GRS-integrated bridge systems, providing for accelerated construction.

GRS technology, supported by the FHWA, has a proven track record in cutting both costs and construction times, especially for county engineering departments that are building relatively shorter two-lane bridges.

Ron Bygness, editor, Geosynthetics

GeosyntheticsMagazine.com | April 20, 2012

U.S. House Transportation Committee Subchairmen John Duncan (R-Tenn.) and Frank LoBiondo (R-N.J.) received their Friend of GMA awards from Boyd Ramsey, GMA executive council chair, and Andrew Aho, GMA managing director. The presentations took place April 17 during GMA’s annual Lobby Day in Washington, D.C.

GeosyntheticsMagazine.com | April 19, 2012

Offered for the first time in the Southeastern U.S.: Classroom training plus hands-on field demonstrations at TRI’s Denver Downs Research Facility.

The explosion in MSE structures installed during the last 20 years has revolutionized the grade-separation solutions currently used in site development construction. Despite this growth—or because of it—there has been an increasing frequency of failures (excessive deformation and collapse) indicating that too many owners, site and wall designers, contractors, and inspection/regulatory agencies are not sufficiently schooled in this construction method.

The Texas Research Institute’s May 22 session in Anderson, S.C., focuses on project responsibilities, construction inspection and quality control, ongoing performance monitoring, and the challenges and costs of effective remediation.

Qualified participants can also obtain Certified Inspector status through the Geosynthetic Certification Institute’s Inspectors Certification Program (GCI-ICP) for MSE Walls, Berms, and Slopes.

The course structure includes current practices, lessons learned from failures, establishing rationale and standard operating procedures for field inspection, documenting visual observations, identifying potential problems, and hands-on construction of MSE structures.

This short course is specifically prepared for: specifying/certifying engineers, construction QC/QA personnel, project managers, installers/contractors, third-party inspectors, and regulators.

GCI Certification Exam

This short course also offers participants the opportunity to take the Geosynthetic Certification Institute’s Inspectors Certification Program (CQA-ICP) for MSE Walls, Berms, and Slopes exam. The exam will be given immediately following the MSE course on May 22 at the same location. The MSE Inspector Exam is part of the GCI Inspectors Certification Program.

Instructors

Instructors for the short course are John Paulson, president of Dison C&S LLC, and Joel Sprague, technical director at TRI Environmental.

For more information and to register, visit TRI/Environmental’s website.

Sources: Texas Research Institute (TRI) and the Geosynthetic Institute (GSI)

GeosyntheticsMagazine.com | April 19, 2012

Tensar International announced in an April 16 press release that construction has commenced on one of the largest highway projects in Ohio—including $3 million to construct MSE (mechanically stabilized earth) retaining walls.

When complete, 30 precast panel retaining walls will be built, totaling more than 200,000 square feet, “making it one of the largest projects in Tensar’s uniaxial geogrid product line history,” the release stated.

The full scope of the Ohio highway project is to construct 22 new bridges, improve safety, reduce road congestion, and connect neighborhoods in Columbus, Ohio. A new travel lane will also be added on Interstate 670 to help reduce weaving across traffic lanes to exits. (Interstate 670 runs through downtown Columbus, connecting I-70 west of downtown with I-270 and U.S. 62 near the eastern suburb of Gahanna.)

The release noted that the first phase of the Columbus Crossroads project is slated for completion in 2014. Kokosing Construction is the contractor for the project.

Source: Tensar International Corp.

Calibration & repair services

Switzerland-based Leister Technologies AG announced in an April 17 press release its new U.S.-based calibration and repair services for its tensiometers.

Annual recalibration is usually required for all tensile-testing devices in the geosynthetics and civil engineering industries. Basic calibration is offered at a fixed low cost with quick turnaround, according to the release. Leister USA’s calibration is compliant with ASTM methodology, the release said.

Leister’s global headquarters is in Kaegiswil, Switzerland, with sales and service centers in more than 90 countries. Leister USA is headquartered in Chicago.

New geofoam product

ACH Foam Technologies has announced its new architectural-grade EPS geofoam product line—Foam-Control Plus+ is an architectural grade expanded polystyrene (EPS) insulation product line with a high compressive strength and high R-value, according to the company.

The product is designed to give architects, designers, and contractors all of the benefits of quality insulation—strength, energy efficiency, and moisture resistance—that also will help keep project costs on track, according to Denver-based ACH.

GeosyntheticsMagazine.com | April 16, 2012

TIGER grants—the U.S. Department of Transportation’s Transportation Investment Generating Economic Recovery program—has money available…but not that much!

Intense competition for DOT grant money, which helps to fund roadway, rail, and other transportation projects deemed to have major regional or national impacts, was revealed once again this month.

DOT reported the first week of April that it had received 703 applications, totaling $10.2 billion, for the 2012 round of its TIGER program—way more than the $500 million it has to award. Applications came in from every state plus the District of Columbia and U.S. territories.

This most-recent TIGER competition is the fourth since 2009. In the first three rounds, DOT received 3,348 applications totaling requests for more than $95 billion. So far, it has awarded $2.6 billion for 172 projects.

Fourth-round distributions will be announced in the next couple of months, a DOT spokesperson says.

Congress mandated that at least $120 million of the $500 million go to projects in rural areas. The DOT also said it wanted to make available up to $100 million of the total for high-speed and intercity passenger rail projects. But Congress zeroed out DOT high-speed-rail funding in both FY 2011 and 2012.

TIGER money can be used to fund up to 80% of a project’s total cost. The DOT’s fiscal year 2013 budget request to Congress includes $500 million for a continued TIGER-like program.

Source: U.S. DOT

GeosyntheticsMagazine.com | April 12, 2012

The Fabricated Geomembrane Institute (FGI) is offering a one-day short course May 21 in Salt Lake City: “Advances and current trends for mining.”

According to an April 11 FGI press release, the day-long course “will be taught by 21 industry professionals from academia, contractors, engineers, installers, and third-party testing personnel.” Prof. Timothy D. Stark from the University of Illinois will lead the course and act as moderator.

The release highlighted several conference presenters and their topics:

• Otis Willoughby on current and emerging regulatory issues.
• J. Pilz and Rio Rinto on geomembrane selection for mining applications.
• Daren Laine on leak location with fabricated geomembranes.
• Frank Sinclair and Steve Hobbs with a hands-on welding and testing demonstration.
• Prof. Stark on coal combustion residuals.
• Bill Shehane on oil spills, development, and production.
• John Heap on canals, reservoirs, and irrigation ponds.

See all speakers and the entire schedule here.

Registration for this FGI-sponsored event is free until April 30, 2012. After April 30, registration for industry professionals is $99, government officials $49. Students are welcome free of charge, the release said.

The short course will be held at the Utah Department of Environmental Quality. Participants are eligible for seven professional development hours (PDHs).

Contact: Laurie Honnigford, FGI representative, +1 651 554 1895.

GeosyntheticsMagazine.com | April 11, 2012

The International Erosion Control Association (IECA) is calling for submissions for Environmental Connection 2013, its annual conference and expo. The 2013 conference is in San Diego, Feb. 10–13.

IECA receives submissions from around the world from instructors hoping to present at this annual event. For its 2013 conference, there are four education tracks:

• erosion/sediment control
• stormwater management
• MS4 management
• surface water restoration

In an April 11 press release, the association noted several hot topics for EC-’13, including: LID (low-impact development), post-construction sustainability, the new federal construction general permit (CGP)—requirements and revisions; effluent limitation guidelines—impacts and opportunities; stormwater management, turbidity control, and stream and shoreline stabilization.

The deadline to submit an abstract is May 31, 2012.

IECA’s Environmental Connection 2013 is Feb.10–13 at the Town & Country Resort in San Diego, Calif., USA.

For more information, visit IECA’s website or contact Katie Laurin or at +1 303 640 7554.

Source: IECA

GeosyntheticsMagazine.com | April 10, 2012

By Ron Bygness

Environmental and public health groups filed a lawsuit April 5 to compel the U.S. Environmental Protection Agency (EPA) to complete its rulemaking on coal ash. A court order could hold the agency to a specific date for issuing a final rule on coal ash.

Coal ash is a byproduct of burning coal to generate electricity. Coal-ash holding ponds are largely unregulated and unlined, including the use of geosynthetic liners (geomembranes or geosynthetic clay liners) for safety.

Environmentalists have called for more-strenuous regulations, particularly since a December 2008 disaster when a containment site in Kingston, Tenn., burst open and flooded 300 acres with coal-ash sludge. That impoundment failure resulted in a multi-year cleanup costing more than $1.2 billion.

Another spill occurred in 2011 in Oak Creek, Wis., near Milwaukee, where a power company’s coal-ash containment pond collapsed and the byproduct sludge slid into Lake Michigan.

The containment facilities in Tennessee and Wisconsin were not lined.

The April 5 lawsuit is intended to force the EPA to complete its rulemaking on coal ash (Appalachian Voices v. Jackson, D.D.C., docket number unavailable, 4/5/12). The lawsuit, filed in U.S. District Court for the District of Columbia, asks the court to set deadlines for the EPA to review and revise coal-ash regulations.

The EPA issued a proposed rule in May 2010 that outlined two options for regulating coal ash. But the agency has not yet issued a final rule, maintaining that it expects to do so by the end of the year. A court order could hold the agency to a specific date.

Earthjustice, representing a coalition of 11 groups, said the EPA has violated section 2002(b) of the Resource Conservation and Recovery Act (RCRA) by not reviewing and revising coal-ash regulations every three years.

The EPA process is intended to determine whether to regulate coal ash as a special waste under Subtitle C of the RCRA, subjecting it to hazardous waste regulations; or as non-hazardous waste—such as municipal solid waste—under Subtitle D, leaving regulation authority with the states.

That proposed rule received more than 450,000 public comments, according to EPA. The Geosynthetic Materials Association (GMA) offered professional testimony regarding geosynthetic lining technologies at eight of these public hearings, which were conducted across the country in 2009–2010.

The environmental-group coalition first filed a notice of intent to sue in January. Among the plaintiffs in the current lawsuit are Appalachian Voices, the Chesapeake Climate Action Network, the Environmental Integrity Project, Physicians for Social Responsibility, and the Sierra Club.

The Utility Solid Waste Activities Group (USWAG) has criticized the Earthjustice lawsuit. Litigation could prevent the EPA from crafting an effective rule and could result in bad public policy, according to the USWAG, an organization that addresses waste issues on behalf of the electric utility industry.

Sen. John Hoeven (R-N.D.) and Sen. Kent Conrad (D-N.D.) introduced legislation last October that would prevent the EPA from regulating coal ash as a hazardous waste and give primary oversight of the material to the states. Companion legislation from Rep. David McKinley (R-W.Va.) passed the House in October, 2011.

Ron Bygness is the editor of Geosynthetics magazine.

GeosyntheticsMagazine.com | April 9, 2012

PRS Mediterranean Ltd. announced in an April 5 press release its “breakthrough customized PRS-Neoweb geocell.”

Using a “reverse engineering approach,” the company said it has developed “a set of unique geocells tailored to four specific project categories, ensuring maximum efficiency and significant cost savings.”

The release stated that the new product is “made from Neoloy—a novel polymeric alloy—PRS-Neoweb geocells stand out because they are available in different design strengths…to ensure optimal performance for each application…with savings of up to 50%.”

Source: PRS Mediterranean

The annual “Call for IFAI board candidates” from the Industrial Fabrics Association International was sent to the association’s voting membership on Monday, April 9. Applications are due May 28, 2012.

In June, the IFAI board’s Leadership Development Committee meets to consider the qualifications of the candidates. In July, the association’s membership is notified of committee’s recommendations.

Election results are announced at the 2012 IFAI Expo Americas, Nov. 7–9 in Boston.

IFAI members are encouraged to recommend candidates for the board:

Cherie M. Schmit
Executive Assistant to the President
Industrial Fabrics Association International
1801 County Road B. West
Roseville, Minnesota 55113
U.S.A.
Ph: +1 651 225 6985
Fax: +1 651 225 6977

U.S. Rep. Paul Broun (R-Ga.,10th) toured the new Crown Resources facilities in Toccoa, Ga. in March, following a town hall meeting at North Georgia Technical College. With Broun (right) are, l-r: Monica Christensen, Crown’s director of human resources; Keith Gardner, vice president of sales; and Monte Thomas, owner and president. Toccoa is in Stephens County in far northeastern Georgia, near the South Carolina border.

Source: Toccoa Record

GeosyntheticsMagazine.com | April 4, 2012

Colbond Inc. and Bonar Technical Fabrics announced in an April 4 press release that the two companies will merge under organizational changes introduced by their parent organization, Low & Bonar PLC, a multinational group of technical textile producers. The release said the merger is “aimed at accelerating growth and putting [the group] on a clear path to globalization.”

The release noted that the portfolios of Colbond and Bonar are complementary: “The merger will create an organization that has the scope and scale necessary for further sustainable global growth.”

Orwig Speltdoorn, a member of the Low & Bonar executive management team and managing director of Bonar Technical Fabrics will lead the integration. He will be supported by Bart Austin from Colbond’s management team, the release said. Jan van Boldrik, Colbond’s CEO for 15 years, was named managing director of Low & Bonar’s Coated Fabrics Division Mehler Texnologies.

Steve Good, group chief executive, Low & Bonar PLC, commented: “These changes are designed to enhance our global reach, accelerate growth, and balance our great operational strengths with a strategic, longer-term market focus. The merger of Bonar Technical Fabrics and Colbond will create a strong platform for further top-line growth and an even wider technology portfolio for our customers.”

Colbond is a producer and supplier of synthetic nonwovens for flooring, automotive, and construction applications and of three-dimensional polymeric mats and composites for civil engineering, building, and industrial applications. The company’s production facilities are based in Emmen and Arnhem, Netherlands; Obernburg, Germany; and Asheville, N.C.

The Bonar Technical Fabrics Group is a producer and supplier of woven fabrics, nonwovens, and fibers for civil engineering, agriculture, and the construction industry. Bonar operates manufacturing plants and offices in Zele and Lokeren, Belgium; Hull, UK; Tiszaújváros, Hungary; and Yizheng, China; with a facility in the Middle East operational in 2012.

Source: Colbond, Bonar Technical Fabrics

Editor’s Note: The following question was posted on the Geosynthetics Facebook page.

Question

Can you please tell me Std-OIT and HP-OIT for a pure unstabilized PP resin?

Answer

The HP-OIT test is preferred for long-term antioxidants that are sensitive to the high temperature of melting in the Std-OIT test. For unstabilized PP and PE, the situation does not arise and therefore the Std-OIT test should be adequate … Bob K.

Dr. Robert Koerner, GSI and GMA Techline

Join the discussion

To post a comment, visit: facebook.com/geosyntheticsmagazine or send your comments to editor Ron Bygness at rwbygness@ifai.com.

Comments and letters can contain opinions of individuals who are writing and do not necessarily reflect the views of Geosynthetics magazine or the Industrial Fabrics Association International.

Geosynthetics | April 2012

By Kevin Harshberger, Ron Zitek, and Chris Eichelberger

Introduction

Description of the A&L Salvage Landfill site in rural northeastern Ohio:

• 400-acre site near Lisbon, Ohio, began operations in 2001.
• a C&D (construction and demolition) landfill with asbestos and “unrecognizable” waste—unauthorized municipal solid waste (MSW).
• 46 acres of waste with no cover.
• leachate seeps.
• strong H₂S (hydrogen sulfide) odor.
• a fire! (aka—a “heating event”).

This site was a former surface coal mine. Most on-site soils were minespoil (a mixture of large rocks and soil). The cover was poor or nonexistent, mainly rocky material. Surface water and air intrusions were high. There were erosion scars and leachate outbreaks on slopes.

The site opened in 2001, but by 2005 the Ohio EPA (Environmental Protection Agency) got involved and findings and orders (F&O) were issued. The F&O established a $3.7 million closure bond and a $400,000 post-closure bond.

The landfill continued to operate from 2005 to 2009, but odors worsened and the U.S. EPA moved in. The U.S. Agency for Toxic Substances and Disease Registry (ATSDR) established an air-monitoring program.

Data gathered between 2008 and 2010 recorded hydrogen sulfide readings as high as 110 parts per billion (ppb). On-site H₂S concentrations were as high as 2,400 ppb. According to ATSDR data from 2006, “exposure to levels [even less than] 100 ppb have been associated with headaches, vomiting, breathing problems, depression, and other symptoms.”

The site stopped accepting waste in February 2009, but there was no action toward closure—the owner(s) had disappeared!

By early 2010, the A&L site was an inactive, but unclosed, landfill with many violations, an intense odor, and a suspected underground fire. The problems at the site called for emergency action, and the OEPA was prepared because of a landmark program it had created just a year earlier.

CLOSER
Moving toward closure

The financial assurance money could be obtained by the state of Ohio, but the question was how it could be spent.

The OEPA is not an environmental contracting agency. With state procurement obstacles (public notice, low bid, wage rates, etc.), how could the OEPA actually do the work?

Using its new CLOSER—Closed Landfills and Orphaned Site Evaluation and Rating—program, established in 2008, the OEPA made the unusual decision to “self-perform” the work.

Unique contracting mechanism

The CLOSER program shortened the time frame at A&L:

• pre-bid meeting for A&L held March 29, 2010.
• design/build proposals submitted April 26, 2010.
• on-site kickoff meeting May 25, 2010.

The project progressed from pre-bid to the start of field work in eight weeks, with no design. Field work was completed in five months.

Compare to conventional time frame

A traditional time frame to establish a contracting mechanism could include:

• 3-6 months to solicit proposals for design.
• 6-9 months for design (including OEPA review).
• possible public hearings.
• 2-3 months for advertisement of construction.
• 2-4 weeks to contract and mobilize.
• a total of 12-19 months before on-site work could start—meaning no work in 2010, maybe not even 2011.

Construction issues

• Phase 1A—Handle the “hot spot”
• Phase 1B—Preliminary cap design (simultaneous with Phase 1A)
• Phase 2—Prepare subgrade (while cap design elements are finalized)
• Phase 3—Construct geosynthetic barrier and protective cover simultaneously
• Phase 4—Restoration

‘Heat event’

A subsurface fire had to be addressed:

• 23 geoprobes installed.
• temperatures in many probes above 140 F (170 F +/-).
• used 12in.-thick recompacted clay barrier to limit air intrusion.
• 7 geoprobes left in place for future monitoring.

Subgrade issues

• Rocky subgrade, virtually no soil
• Exposed piles of ACM (asbestos-containing materials)
• Top of landfill very flat
• No defined benches
• No defined benches

Excavating the exposed piles of asbestos-containing materials in preparation for smoothing the subgrade. Image courtesy of R.B. Jergens Contractors.

Dozers, trucks prep the subgrade to construct benches for slope stability. Image courtesy of R.B. Jergens Contractors.

Dozers, trucks prep the subgrade to construct benches for slope stability. Image courtesy of R.B. Jergens Contractors.

Subgrade prep for the geosynthetics layers. Image courtesy of R.B. Jergens Contractors.

Subgrade prep

• Excavated exposed ACM and moved it to top of landfill
• Dozers, compactors, and smooth drum rollers smoothed the subgrade (no need to add soil)
• Constructed benches for slope stability
• All work done as a lump sum, minimizing owner’s risk

Benefits of regulatory-led design/build

• OEPA’s geotechnical engineer identified potential slope stability issues.
• OEPA worked side by side with contracting, engineering, consulting, and installation teams.
• Several iterations of the bench configuration were discussed before a final design was determined.
• Slopes remained stable during and following construction.

Gas and odor control

• A geocomposite layer was installed under the cap to provide a collection mechanism.
• Composite was strategically placed to control costs.
• A collection trench was provided at the top of the hill.
• Installed 4-in. HDPE (high-density polyethylene) connections above grade to allow installation of passive solar flares.
• At OEPA’s suggestion, installed additional 4-in. HDPE connections spaced at 1/acre.

The “gas venting layer” of geocomposite material was installed beneath the 40-mil LLDPE textured geomembrane. The geocomposite gas venting layer was installed using a 15ft-wide roll of material on the subgrade, with a spacing of approximately 70ft between panels. The geocomposite material was installed directly prior to installation of the geomembrane, because strong winds could have displaced the geocomposite strips. Photo courtesy of AEG.

Installation of the 40-mil LLDPE textured geomembrane over the approved subgrade layer. The geomembrane was deployed in a downhill direction and ballasted with sandbags to prevent wind uplift. Panels are positioned to ensure proper seam overlap and then fusion welded as the membrane is deployed across the project. A pipe boot was later installed to seal the penetration from the HDPE pipe penetration. Photo courtesy of AEG.

A section of installed geomembrane on the A & L project. This photo displays the various grade changes and angles for the project. In general, geomembrane seams should be constructed parallel with the slope. This requirement creates the need to install the geomembrane from different setup points and requires additional seaming. Photo courtesy of AEG.

Geosynthetics facts

• Gas geocomposite—453,115sf
• 40-mil LLDPE (linear low-density polyethylene)—2,029,914sf (46.6 acres)
• Drainage geocomposite—2,029,914sf
• Subgrade prepped just ahead of installation crews
• All geosynthetic work was done in seven weeks (3 acres/day)

“The Ohio EPA utilized this site’s financial assurance and a design-build contract to speed forth on closure, the exemplary success of which may provide a template for future closure responses. AEG—an Approved Installation Contractor (AIC) as recognized by the International Association of Geosynthetic Installers (IAGI)—was proud to be part of this first-of-its-kind collaboration among regulators, designers, and contractors.”
–Chris Eichelberger

Conclusions

Summary of work

• Clay for “hot spot”—17,337cy
• Subgrade prep—120,000cy (+/-)
• Geosynthetics—4,512,943sf (103.6 acres)
• Protective cover soil—138,637cy
• Riprap channels—5,563lf
• Seeding and mulching—90.3 acres all in five months, with no design ahead of time!

Lessons learned

How was the A&L Salvage Landfill closed in just five months, two weeks ahead of schedule?

1. Hands-on, directed efforts of regulators—the regulators were large stakeholders. They took on the role of “owner.”
2. Key contractor relationships and “transparency”—the OEPA saw one entity, not three.
3. Design/build team not only had proven individual experience, but also experience with each other.
4. Entire team put high focus on communication.

Project Manager—Kevin Harshberger, P.E., vice president–R.B. Jergens Contractors Inc.
Certifying Engineer—Ron Zitek, P.E., senior engineer–North Point Engineering Corp.
Chris Eichelberger, director of business development–American Environmental Group Ltd.
Ron Bygness, editor of Geosynthetics, also contributed to this article.
This article is adapted from an Aug. 25, 2011, presentation by Kevin Harshberger at Wastecon-2011 in Nashville, Tenn.

By Donald E. Hullings and Hal S. Boudreau III

Abstract

In light of the new emphasis on our carbon footprint, this article revisits the sustainable landfill concept envisioned more than a decade ago.

The sustainable landfill idea was conceived before its time and became lost in the myriad solid waste management options proposed in lieu of landfills. While the original concept considered sustainability in terms of a landfill that could be “reused,” it can also be viewed in terms of today’s focus on sustainability and how it relates to greenhouse gas emissions.

This article takes a fresh look at how landfills can achieve goals for managing waste in an environmentally friendly and cost-effective manner. It will also explore the greenhouse gas emissions associated with the four stages of landfill operations, how geosynthetics have already improved landfill performance, and how they are the key to eventually fulfilling the promise of a sustainable landfill.

Introduction

It has been less than two decades since the United States moved from garbage dumps to sanitary landfills with the promulgation of federal “Subtitle D” regulations.

Since that time, great strides have been made in landfill technology, particularly the use of geosynthetics as effective replacements of natural materials such as clay and gravel. Even so, the current trend is away from landfills and toward a wide array of more eco-friendly alternatives including recycling, waste-to-energy, and composting.

Traditional landfills, however, remain the most cost-effective short-term disposal option in most cases. The choice is seemingly not a new one—cost vs. environment impact.

Perhaps there is another solution. The promise of the sustainable landfill is to provide a cost-effective and environmentally sound waste management solution by combining green energy production, recycling, and eventual disposal in one operation. The sustainable landfill can effectively use and preserve valuable resources and minimize impacts associated with greenhouse gases.

As this article demonstrates, geosynthetics play instrumental roles throughout the process.

The concept

The sustainable landfill, as envisioned by Environmental Control Systems Inc. (ECS), is composed of four stages as shown in Figure 1:

1. Cell construction
2. Filling cell and bioreactor construction
3. Bioreacting
4. Landfill mining

By enhancing decomposition and eventually mining the waste to reclaim airspace, the original concept envisioned a landfill that could be effectively reused. Such a landfill would avoid the costs of future land acquisition, cell construction, and infrastructure, as well as the issues with siting a new landfill.

More importantly, the revisited sustainable landfill will focus more on material recovery and power generation than disposal. The use of geosynthetic materials has already allowed the reduction of the carbon footprint in terms of landfill construction, but the ultimate potential is to use geosynthetics in early collection and control of landfill gases.

The stages of the landfill and the key role played by geosynthetics are discussed below.

1. Cell construction

The sustainable landfill incorporates many of the same advances of the current modern landfill. Figure 2 compares the typical system used in the 1990s and the system most often used in Florida today.Using layers of geosynthetics results in considerable savings both in construction costs and in landfill capacity since geosynthetics are much thinner than the earthen layers they replace.

The geomembrane/GCL composite is now used more than the prescriptive geomembrane/compacted clay layer and has been shown to have advantages over compacted clay. Advances in high-transmissivity geocomposites allow for shallower bottom grades or increased spacing between collection pipes.

High transmissivity geocomposites also reduce the head of the liners below that which can be achieved with gravel and are very important when recirculating leachate in the bioreactor process. Geogrids are used to stabilize foundations and sideslopes or in mechanical stabilized earthen berms around the landfill perimeter to further increase capacity.

Beyond the cell construction, geosynthetics can be used in other landfill infrastructure—from lining leachate ponds to roadway reinforcement and drainage. Manufactured materials also allow for more reliable and easier construction vs. the variability of natural materials.

The total landfill emission factors reported by the U.S. Environmental Protection Agency (EPA) are made up of the following components:

• CH₄ (methane) emissions from anaerobic decomposition of biogenic carbon compounds.
• transportation CO₂ (carbon dioxide) emissions from landfilling equipment.
• biogenic carbon stored in the landfill.
• CO₂ emissions avoided through landfill gas-to-energy projects.

Although the move to geosynthetics has been largely motivated by financial benefits, the carbon footprint can be greatly reduced when considering the greenhouse emissions resulting from manufacturing, transporting, and installing the various landfill components. For example, we compared the greenhouse gas impacts from the construction of a typical 10-hectare (25-acre) landfill cell for a prescriptive landfill cell (circa 1993) to that of a landfill of today in Florida. We were particularly interested in the greenhouse gas impacts on a per-ton-of-waste basis to get a better idea of the cost of disposal.

The 10-hectare cell could contain about 1,750,000m³ of waste or 3,364,000 metric tons, depending on waste density. The greenhouse gas emissions for the various components are taken from “Emission Facts” (EPA, 2005) with results summarized for our simplified 10-hectare site in Table 1.

More detailed information on the various components can be found in other papers presented at “GRI 24—Optimizing Sustainability Using Geosynthetics.”

The original sanitary landfill design (Figure 2) has more layers comprised of soil, which do not have to be manufactured and are available locally but still have significant transportation costs because of the sheer volume of material. For our landfill, we assumed a haul distance of 30km (18.5mi) for clay and gravel, and 10km (6.2mi) for soil cover, but this is certainly optimistic for much of Florida.

This “soil-rich” base liner and leachate collection system construction emits approximately 14,200,000kg CO₂ for the 10 hectares or 4.22kg CO₂ per metric ton of disposed waste.

Conversely the “geosynthetic-rich” alternative emits only approximately 4,560,000kg CO₂ or 1.36kg CO₂ per ton, including manufacturing, transportation, and installation. In fact, more of the emissions results from the protective soil layer than all of the geosynthetic components combined.

Although haul distances are typically much greater for the geosynthetics, much less material needs to be hauled. In our example, we have not counted any increase in airspace as a result of the geosynthetic option, but reducing the thickness of the liner and leachate collection system by a few feet can increase airspace by as much as 5%.

Actual emission values can vary significantly depending mainly on location and the availability of suitable soils, but the conclusion is apparent—although driven primarily by financial savings and increases in capacity, the switch to using geosynthetics in today’s alternative landfill has resulted in a significantly smaller carbon footprint for the same size landfill footprint.

See the Appendix for computational details.

2. Filling cell and bioreactor construction

A vital component of the sustainable landfill is to operate it as a bioreactor.

Unlike the “dry tomb” landfill designed to keep water out, the bioreactor recirculates leachate and adds water as necessary to enhance decomposition. This natural process creates additional landfill capacity, increases the production of methane that is collected and used as fuel, and decreases operational expenses and energy associated with mechanical or manual separation.

A bioreactor also stores leachate and may reduce long-term maintenance and monitoring over that of traditional landfills as the decomposition process is condensed and the waste and leachate become more benign. Because distribution of moisture and collection of additional gas are critical in a bioreactor, geosynthetics have additional applications in this process.

Drainage composites and pipes can be used throughout the landfill as waste is being placed. Trenches can be constructed in the waste-to-place pipes, geocomposites, or other drainage materials (Figure 3) or a planar system can be placed and covered.Vertical wells can also be constructed after waste is placed to serve as moisture distributors and/or gas collectors.

In re-examining sustainability in terms of impacts to the environment, gas collection and control during the waste-filling process are paramount. Current federal Title V regulations do not require gas collection until five years after waste is first placed. Through decomposition, tons of greenhouse gases are emitted during that period—orders of magnitude more than the greenhouse gases associated with the liner construction.

pproximately half of the landfill gas is methane, which has more than 20 times the impact on the environment than CO₂. The sustainable landfill provides gas collection and control from the beginning. A gas collection system can be constructed directly below the first lift of waste, and gas can be collected through the leachate collection system.

Horizontal gas collectors, pipes, or even geocomposites can be placed over waste lifts as the landfill is being filled. Tarps, which are basically thin reinforced geomembranes, can be placed over inactive filling areas or even placed overnight to help contain gases. While great advances have been made in reducing the impacts of construction, more focus must be placed on containing landfill gases during the filling operation in a truly sustainable landfill.

3. Bioreacting

Although waste decomposes during filling, most decomposition occurs after the cell is filled. As Figure 4 shows, decomposition (measured by gas production) can take decades in a “dry tomb” landfill.

In our 10-hectare cell, peak gas production is five times that of a traditional landfill and a bioreactor can accomplish the majority of decomposition within years. The previous emphasis of the sustainability landfill was to enhance decomposition to reclaim the airspace. Today’s focus is on containing the gas to reduce emissions and generate green power.

An average landfill emits 1150kg CO₂ e/metric ton—three orders of magnitude greater than the construction impact of our geosynthetic liner system. However, landfills that incorporate a good cover, have a gas recovery system, and generate electricity can have zero net emissions (EPA, 2006).

A geomembrane cover with horizontal gas collection can collect 99% of the methane that would have escaped the landfill (Van Kolken Banister, 2010). The single greatest way to optimize sustainability in terms of reducing the carbon footprint is to decrease emissions from decomposition.

At this stage, an exposed geomembrane cover (EGC) is an ideal cover system (Figure 5).In addition to containing the methane gas, an EGC contains potential seeps of leachate and controls odors and vectors. At half the cost of traditional covers (Koerner, 2011), an EGC also eliminates concerns regarding the stability and erosion of soil covers and provides more operational flexibility such as adding wells and moving pipes since the geomembrane is not covered with soil.

Also, much like the cost for the liner construction, the emissions from the construction of an EGC can be much lower than a traditional cover. The addition of solar panels on the EGC can be another source of green energy.

4. Landfill mining

After bioreacting, the landfill is mined to recover the usable materials—de facto recycling.

The organic component of the waste has been greatly reduced, which facilitates easier separation and sorting. The waste can be excavated and screened (Figure 6), and the larger particles (“overs”) can processed to recover valuable recyclables.

The smaller particles (“unders”) from screening can be placed in the new cell as daily or intermediate cover for further decomposition, possibly processed further into a compost or another use in the future. Delaying the processing of the harder-to-recycle materials such as plastics until the landfill mining stage may allow the recycled markets time to develop methods to provide greater revenues per ton and allow a wider variety of materials to be effectively recycled than can be done currently.

Future technologies may provide more options for the economic and environmentally sound use of the residuals and recycled materials. Valuable resources are not discarded in the sustainable landfill but are simply stored to use in the future. Geosynthetics can be used during this stage as temporary cover for stormwater and odor control during the mining process.

Overall impacts of the sustainable landfill

We have examined the sustainability for each stage of the operation, particularly in regard to greenhouse gas emissions, but there are also some overall benefits.

Going back to the original concept, the lined cells can be reused after mining, so impacts of future landfill construction are dramatically reduced. By offering the benefits of waste-to-energy, composting, and recycling in one facility, multiple trips to different facilities and the associated emissions can be eliminated.

Significant barriers to other technologies, such as large capital costs for waste-to-energy plants or poor markets for some recyclable materials, are eliminated in the sustainable landfill. Traditional landfills are usually the most cost-effective means of disposal, but the sustainable landfill can be just as cost-effective while also being carbon neutral.

Summary and conclusions

The application of geosynthetics in landfill designs has resulted in significant savings in construction costs and capacity. Although not the primary intention, the use of geosynthetics has significantly reduced the carbon footprint. Impacts can vary dramatically and are certainly site specific, but greenhouse gas emissions can easily be cut in half and perhaps even more.

At this stage, we have done what we can to reduce the construction footprint, but the key to overall emissions lies in the cover. In a broader view, using geosynthetics during landfill filling to enhance gas collection and constructing a geomembrane cover to contain gases after filling are the critical elements to reduce emissions.

The sustainable landfill, with a geosynthetic cover and operating with landfill gas recovery and electricity generation, can result in a carbon-neutral landfill.

Don Hullings and Hal Boudreau are with the Jones Edmunds office in Gainesville, Fla.
The articles in this series encompass all types of geosynthetics and their applications viewed from the context of sustainability. Traditional solutions are compared with geosynthetic solutions from both cost and carbon footprint perspectives. (from the Geosynthetic Research Institute’s 24th conference, 2011)

References

ECS Inc. (2006), “Full-Scale Application of an Aerobic Landfill Bioreactor System,” Proceedings 11th Annual SWANA Landfill Symposium, Nashville, SWANA Publication.

Koerner, R. and Geosynthetics Institute (2011), “Traditional vs. Exposed Geomembrane Landfill Covers: Cost and Sustainability Perspectives,” Proceedings GRI-24 Conference, Dallas, GSI publication, Folsom, Pa.

U.S. EPA (2005), “Emission Facts,” Office of Transportation and Air Quality, EPA 420-F-05-001, February.

U.S. EPA (2006), “Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks,” ICF International for EPA, see http://epa.gov/climatechange/wycd/waste/SWMGHGreport.html#sections.

Van Kolken Banister, A. and Sullivan, P. (2010), “LFG Collection Efficiency: Debunking the Rhetoric,” MSW Management, Vol. 20. No. 4, pp. 26-32.

Geosynthetics | April 2012

By Robert M. Koerner and John A. Wilkes

Abstract

The 2010 International Commission on Large Dams (ICOLD) Bulletin on “Geomembrane Sealing Systems for Dams” (ICOLD Bulletin No. 135) supersedes and greatly expands upon two earlier versions published in 1981 (Bulletin 38) and 1991 (Bulletin 78).

The 265 dams incorporating geomembranes cited in this new Bulletin include 183 fill, 47 concrete, 34 roller compacted concrete, and 1 hybrid. Of the total, 118 (45%) are in Europe, 48 (18%) are in the United States, 47 (18%) are in China, and the remaining 52 (19%) are scattered in other countries and locations.

Since most of the experience gained to date is in Europe, the European Working Group on Geomembranes prepared the Bulletin with the assistance of the primary author of this article.

This article attempts to summarize the 242 pages of the English-language portion of the Bulletin and is subdivided according to the same structure. The Bulletin concludes with a brief section on quality control and another on guidance for technical content of contracts. It is published in English and French.

Introduction

For more than 45 years geomembranes have been used to provide waterproofing on various types of large dams. Table 1 provides information on the 265 dams cited and detailed in this Bulletin as of 2006.Most have been installed in the dry, but some success at underwater sealing has also been achieved.

By far the largest proportion of these dams have used factory-manufactured polymeric geomembranes. When such geomembranes incorporate other types of geosynthetic materials, such as geonet drains and geotextile cushions, filters, or separators, a “geomembrane sealing system” (GSS) is achieved and will be referenced as such throughout this article. In the majority of cases the waterproofing is a GSS, although a few situations have the geomembrane by itself.

As stated, the waterproofing geomembranes used in these dams are largely polymeric, although 22 are bituminous and four are in-situ (or spray-on) types. Since in-situ types are no longer used and bituminous types are currently rare, the Bulletin focuses almost entirely on polymeric geomembranes made from various types of resins and their related formulations.

Materials, testing, durability

Most of the geomembranes cited in this Bulletin are made from thermoplastic polymers (those that can be thermally welded in the field), with European-manufactured polyvinyl chloride (PVC) the most widely used. Table 2 presents these statistics.

Recognize, however, that all polymers are actually formulations containing the designated resin (from which the name is derived), additives (mainly antioxidants), colorants (often carbon black), and some fillers. Geosynthetic literature is abundant on details of manufacturing quality control and quality assurance. The Bulletin provides a detailed comparative behavior of the various geomembranes. Table 2 shows that both exposed and covered situations are encountered and in approximately equal proportions.

The Bulleton covers testing of the manufactured geomembrane in the context of providing the desired information for various situations. Both ISO and ASTM Standards are identified. Individual tests for the following situations are include:

• quality control during manufacture
• identification testing
• performance testing
• compliance testing

Regarding the important issue of geomembrane aging and its in-service durability, a critical issue is whether the geomembrane is exposed or covered with soil, rock, or concrete. The former is more critical due to ultraviolet exposure and the usually high accompanying temperatures. This topic is addressed in the Bulletin. In this context, however, note that the oldest exposed geomembrane installation was in 1974 and the oldest covered installation was in 1960.

While not in the Bulletin, note that research at the Geosynthetic Institute on exposed geomembrane lifetime prediction is ongoing.

Loads applied to geomembrane sealing systems (GSS)

Table 3 illustrates various dam configurations and their respective GSS locations for 254 of the dams cited; the remaining 11 are special cases.As can be envisioned, mechanical loads are certainly to be anticipated. The following are addressed in the Bulletin:

• gravity load
• subgrade differential settlement
• puncture loads
• wind uplift
• reservoir waves
• ice in the reservoir
• uplift from water and air

Various physical, chemical, and biological agents can be important on a case-by-case basis, including:

• heat
• ultraviolet radiation
• water contamination ingredients
• biological activity, e.g., microorganisms
• vegetation
• fauna
• vandalism

Each of these topics is discussed in the Bulletin but to a limited extent.

Geomembranes for new and rehabilitated earth and earth/rock fill dams

Table 4 indicates that both new and rehabilitated fill dams (earth and earth/rock types) are commonly waterproofed using geomembranes on, or in, their upstream slopes.This is the most widely used GSS application reported in the Bulletin.

When used on the upstream slope of fill dams, cover is provided by a geotextile cushion (typically a thick needlepunched nonwoven fabric) and then rock riprap or articulated concrete block mattresses on the surface. Most cases are of this general type. See Figure 1 for typical situations.

As seen in Table 4, a relatively high number of fill dams (47 cases) also use GSS without being covered—i.e., in a exposed condition. Confidence in geomembrane durability appears to be a factor because many of these dams are recent case histories. It is important to note that the geomembrane can be visually inspected as to its performance whenever the water level is lowered.

Internal GSS have been used in 20 large fill dams, most of them in China. The Bulletin gives numerous cost-effective placement options in comparison to conventional core walls made from clay or asphalt concrete. The internal GSS is also applicable to raising the height of existing dams.

In essentially all cases of geomembranes used with fill dams (geomembrane/geosynthetic clay liner composites were not mentioned in the Bulletin), a drainage layer is used beneath the geomembrane, creating a “system.” This drainage layer is either a thick needle punched nonwoven geotextile or a geonet composite with two geotextiles thermally bonded to it on both sides. This allows easy placement on a steep slope or even vertically.

Interface stability is important and direct shear testing is required. The inclined drainage system empties into a horizontal drainage gallery beneath the embankment and is discharged at the toe of the downstream slope. This drainage gallery is typically granular soil of adequate thickness and permeability so excess pore water pressures are not mobilized beneath the downstream embankment portion of the dam. Many configurations are illustrated in the Bulletin.

Geomembrane achorage is emphasized in a number of sections of the Bulletin.

Clearly, at the two abutments and the foundation, leakage must be minimized. Concrete beams, or “plinths,” are common. These plinths are cast with connections of various types integral with their construction. They can be continuous (with the geomembrane welded to polymer inserts) or discrete (with anchor bolts, batten strips, and associated hardware to physically fasten the geomembranes). These are critical design details.

If the strategy is for exposed geomembranes on fill dam slopes, wind and wave forces can be significant in shifting the geomembrane out of position. This will require intermediate anchorages throughout the slope. Several scenarios are presented in the Bulletin.

The seaming of the geomembrane rolls together on the slope is arguably the most important construction issue for a GSS. With thermoplastic geomembranes of the type currently used, welding of edges and roll ends is straightforward. Hot air welding can be done at any angle (even vertically) and can even be done with two parallel tracks leaving an unbonded space between. This so-called “dual channel” seam allows for air inflation and is an excellent nondestructive test of the completed weld. If flaws are detected, conventional patches or cap strips are used and retested using the vacuum box method.

Geomembranes on concrete and masonry dams

Table 5 presents statistics on the use of geomembranes in the rehabilitation of poured concrete and masonry dams. (Roller compacted concrete dams will be treated separately.)In all cases except one, the geomembranes are exposed. It is current practice to always include drainage (and cushioning) behind the geomembrane thus creating a GSS. There are no instances of using GSSs in newly designed concrete dams.

In most of the cases, a grout curtain is first constructed to minimize foundation leakage. A concrete beam (or plinth) is constructed over the grout curtain, which serves to anchor the base of the geomembrane and provide proper waterproofing. A drainage system (thick geotextile, geonet, geonet/geotextile composite, or geotextile/geonet/geotextile composite) is always used on the face of the dam to collect any seepage that bypasses the geomembrane. This drainage system leads to the dam’s existing drainage gallery where it is collected, monitored, and released downstream. Many variations are illustrated in the Bulletin. The drainage system also serves as an antipuncturing layer. Figure 2 shows such dams while being waterproofed and Figure 3 shows the final situation.

Regarding attachment to the face of the dam, experience over the years has led to linear, vertical anchorages of wide geomembrane panels as the preferred strategy. The spacing between vertical anchorages (typically 3-5m) and the type of anchorage system must leave the geomembrane panels adequately smooth, yet properly tensioned. Aesthetics is also a consideration and black geomembranes are never used, whereas any color (often gray) can be formulated providing that proper ultraviolet durability is achieved. The most common loads resisted by the exposed geomembrane panels are wind and uplift.

Geomembranes for roller-compacted concrete (RCC) dams

As illustrated in Table 6, 32 RCC dams incorporate a geomembrane as the watertight element.Most cover the entire face of the dam; however, five of them cover the joints and cracks only.

As seen in Table 6, approximately half of the geomembranes are exposed and the other half covered. The exposed solution has many similarities to the concrete and masonry dam rehabilitation schemes presented in the previous section (see Figure 4).The covered solution (known as the Winchester System) uses a composite geomembrane/ geotextile that is prefabricated onto a concrete panel (see Figure 5).

This panel is then used as the upstream forming system of the RCC dam with the geomembrane facing the concrete as it is being placed. The geomembranes between panels are cap-stripped and hot air welded together to form the continuous geomembrane. This configuration allows the concrete panel to act directly against the impounded reservoir, thus protecting the geomembrane against ultraviolet exposure, puncture damage, and vandalism. It has been used on 10 dams in the United States.

Special cases

Special cases include waterproofing of joints on concrete dam faces for both new and rehabilitation situations. They sometimes are constructed under water. The Bulletin presents Table 7 in this regard and Figure 6 illustrates several situations.

The use of water stops (both embedded and external) in RCC dams is important in these spacial cases. The geomembrane must have excellent elasticity and flexibility, while also having the requisite durability. Good tear and puncture resistance is also required—and sometime burst resistance as well.

Quality Control (QC) and Quality Assurance (QA)

Because proper QC and QA are important, a separate chapter in the Bulletin was necessary. When dealing with geosynthetic materials, there are manufacturing and construction issues. When properly practiced, the four following interconnected quality issues lead to an acceptable project:

• MQC = manufacturing quality control at the factory
• MQA = manufacturing quality assurance at the factory
• CQC = construction quality control in the field
• CQA = construction quality assurance in the field

ISO 9000 certification for the manufacturing considerations (both MQC and MQA) and certification of both installers (for CQC) and inspectors (for CQA) are currently available for field personnel.

The Bulletin is quite detailed in giving guidance to the type and number of tests for MQA and CQA personnel to require. Some generic specifications for different types of geomembranes are currently available. Installation of the geomembrane sheets/panels as well as fastening systems are described.

Guidance on technical content of contracts

Regarding contracts, it is recommended separating the GSS waterproofing contract from the earthwork or concrete construction contract because GSS waterproofing projects require completely different work personnel and skill sets from conventional dam contractors.

Much important information about contracts is included in the Bulletin. A few points:

• A quality control plan must be submitted with the bid documents.
• It is common to specify the total acceptable leakage from the upstream face or from each compartment.
• It is typical to require a warranty on materials and a warranty on installation.
• Quality, not cost, should be the major consideration in the selection process of a contractor supplying a GSS.

Robert M. Koerner, Ph.D., P.E., NAE, emeritus professor of civil engineering at Drexel University and director of the Geosynthetic Institute in Folsom, Pa. He is a member of Geosynthetics magazine’s Editorial Advisory Committee.
John A. Wilkes, P.E., is president of Carpi USA Inc. in Roanoke, Va.
This article is adapted from a paper presented Sept. 28, 2011, at the Association of State Dam Safety Officials conference in Washington, D.C.

Acknowledgements

ICOLD Bulletin No. 135 was prepared by the European Working Group, consisting of the following members: E. Aguiar Gonzalez (Balsas de Tenerife, Spain), P. Barkek (Swiss National Committee), M. Blanco Fernandez (Laboratorio Central de Estructuras y Materials C.D.E.X., Spain), P. Brezina (Povodi Odry, Czech Republic), H. Brunold (Austrian National Committee), D. Cazzuffi (ENEL CESI, Italy), H. Girard (Cemagref, France), M. Lefranc (French National Committee), J. L. Machado do Vale (Portuguese National Committee), C. Massaro (Azienda Energetica Metropolitana Torino), J. Millmore (British National Committee), L. Schewe (German National Committee), A. Scuero (Italian National Committee), P. Sembenelli (Italian National Committee), G. Vaschetti (Italian National Committee), with the assistance of R. M. Koerner (Drexel University/GSI, USA).