Building better walls

March 2012 » Features » PROGRESSIVE ENGINEERING
Geosynthetic Institute offers a new field inspector certification program to improve the performance of geosynthetic-reinforced MSE walls, berms, and slopes.
Robert Koerner, Ph.D., P.E.
GSI's Mission is to develop and transfer knowledge, assess and critique geosynthetics, and provide services to the member organizations.

We at the Geosynthetic Institute (GSI) have been encouraged by our members to provide field inspector certification in two specific areas. The first program (initiated in 2006) is focused on the installation of geosynthetics at waste containment facilities. The program presently has 422 certified inspectors for geosynthetic installation and 388 certified inspectors for compacted clay liner installation.

The second program (initiated this year) is focused on mechanically stabilized earth (MSE) walls, berms, and slopes that are reinforced with geosynthetics. The program presently has 12 certified inspectors.

The two inspector certification programs differ not only in their technical content but also in the impetus from which they were initiated. The waste containment program was requested by environmental agencies, as well as landfill owners and operators, because of the sensitive nature and significance of liner leakage at solid waste landfills and liquid surface impoundments. The MSE walls, berms, and slopes program was initiated because of the number of failures – both excessive deformation and actual collapse – that have occurred and appear to be ongoing.

GSI currently consists of 71 member organizations of which about 45 percent are international.

While the overall performance of MSE walls, berms, and slopes using geosynthetic reinforcement might be considered as being reasonable, it has certainly been less than perfect. At a GSI workshop held on April 1, 2010, representatives from about 20 member organizations suggested the need for a program to reduce the causes for such failures. It also was discussed that inadequate design and improper construction were the root causes of the failures in part because there was rarely any construction oversight that could have identified both the design inadequacies and the construction deficiencies.

GSI's inspector certification program is aimed at correcting these issues. This two-way orientation by field inspectors – notification of design anomalies and correction of contractors errors – should help stem the number of failures of MSE walls, berms, and slopes.

Inspector requirements
A potential candidate for inspector certification for MSE walls, berms, and slopes using geosynthetic reinforcement must:

  • be recommended by his or her immediate supervisor;
  • have a minimum of six-months of documented field experience in like situations; and
  • pass a multiple-choice examination on the subject matter.

As with all inspection services, the certified inspectors serve as the owner/designer/regulator's agent in the field to see that the site-specific plans and specifications are met or exceeded. In this regard, they provide feedback as to the situation on an ongoing basis. They also interact directly with the general contractor and subcontractors in regard to observing the construction details as the facility/system is being built. Solicited advice (but not operational directions) by knowledgeable and experienced certified inspectors can be very helpful in many situations.

GSI's mission is to develop and transfer knowledge, assess and critique geosynthetics, and provide services to its member organizations. GSI is a consortium of organizations interested in and involved with geosynthetics. All types of polymeric geosynthetic materials are involved: geotextiles, geomembranes, geogrids, geonets, geocomposites, geosynthetic clay liners, geopipe, geocells, and geofoam. The organization includes federal and state governmental agencies, facility owners, designers, consultants, quality control and quality assurance organizations, testing laboratories, resins and additive suppliers, manufacturers, manufacturer's representatives, and installation contractors. GSI currently consists of 71 member organizations of which about 45 percent are international.

The Geosynthetic Certification Institute-Inspectors Certification Program (GCI-ICP) for "MSE Walls, Berms and Slopes Using Geosynthetic Reinforcement" is administered by the Geosynthetic Certification Institute, which is a branch of GSI.

Robert M. Koerner, Ph.D., P.E., is the emeritus director of the Geosynthetic Institute and emeritus professor at Drexel University. His interest in geosynthetics spans 32 years of teaching, research, writing, and consulting. He can be contacted at robert.koerner@coe.drexel.edu. George R. Koerner, Ph.D., P.E., is the recently appointed director of the Geosynthetic Institute. He can be contacted at gkoerner@dca.net.

Information on GSI's certification programs is available at www.geosynthetic-institute.org One-day courses offered on each of the certification programs are regularly announced on the website under the "Education" heading.


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