Thank you to all who participated in our recent webinar, “Best Practices for Installing the GEOWEB® Geocell System,” and for submitting your technical questions regarding GEOWEB® Geocells.

Based on the discussion and submitted inquiries, we’ve compiled answers to some of the most frequently asked topics to help clarify how the GEOWEB system works and where it delivers the greatest value.

If you didn’t catch the live webinar, view the on-demand webinar here and earn PDH credits.

Q1. How difficult is it to address a poor or failed subgrade with GEOWEB Geocells?

Addressing a poor subgrade with the GEOWEB systems is typically straightforward and highly effective when properly designed. Rather than relying on deep undercutting or chemical soil treatment, the GEOWEB system mechanically stabilizes weak soils by confining the infill and distributing loads laterally. This reduces vertical stress on the subgrade and minimizes rutting and shear deformation. From a construction standpoint, installation is simple and often completed with only minimal subgrade preparation. Even in very weak conditions (CBR < 3%), the GEOWEB system can significantly reduce required aggregate thickness while improving overall performance, making it a more reliable and more cost-effective solution than traditional stabilization methods.

To eliminate uncertainty, we offer a free project evaluation service. By submitting basic project details including subgrade strength, vehicle type and number of passes, our engineering team can assess site conditions and recommend an appropriate, project-specific solution.

To receive a free project evaluation based on your site specific conditions, please submit your project details at: https://www.prestogeo.com/free-project-evaluation/

Q2. Why is geotextile fabric installed beneath the GEOWEB Geocells for load support applications?

A geotextile, either a non-woven or enhanced woven (high performance) is placed below the GEOWEB system to preserve long-term performance by providing separation, filtration, and controlled drainage. In low subgrade CBR conditions or where differential settlement may be a concern, enhanced woven geotextiles are typically used.

When enhanced woven geotextiles are used, they help prevent soil migration and clogging while also providing additional reinforcement and the ability to bridge localized weak or soft areas.

Please Note: Slit tape woven geotextiles are not recommended for the GEOWEB Load Support applications. Slit tape geotextiles do not provide adequate filtration and have limited drainage capability, with typical open areas of only 1 to 2%.

As part of our free evaluation, our engineering team will recommend the appropriate geotextile type and strength based on site specific conditions. To receive a free project evaluation, please submit your project details at: https://www.prestogeo.com/free-project-evaluation/

Q3. How much of a wear surface is required over the top of the GEOWEB system?

For load support applications, a wear surface is typically placed over the GEOWEB system. The required material type and thickness depends on the specific application, loading conditions, traffic type, and desired surface type (aggregate, asphalt, concrete).

All load support applications require some form of wear surface to protect the system and ensure proper load transfer. In other applications, such as slope protection and channel armoring, the infill is flush with the top of the GEOWEB geocell.

Overall, cover requirements are project-specific and should be determined based on design criteria and site-specific conditions, but a minimum of 2” is generally required.

Q4. Are the ATRA® Stakes driven through the geotextile underlayment?

For load support applications, ATRA Stakes are generally not required unless the roadway is on a slope. In slope protection or channels armoring applications, ATRA Stakes are typically driven through the geotextile to ensure the system remains securely positioned during infilling and to transfer loads into the subgrade, helping to prevent sliding and enhance overall system stability.

ATRA Stake spacing and installation pattern are determined through the free project evaluation based on your specific site conditions; therefore, the use of standard tables and graphs is not recommended, as each project has unique design requirements. To receive a free project evaluation, please submit your project details at: https://www.prestogeo.com/free-project-evaluation/

Q5. What is the typical design life of GEOWEB Geocells?

The design life of the GEOWEB System can be tailored to meet specific project requirements. Roadway projects commonly require a 20-year design life, while other civil or infrastructure projects may require 50 to 100 years. GEOWEB Geocells are manufactured from a proprietary blend of 100% virgin high-density polyethylene (HDPE) stabilized with 1 to 2% carbon black. Carbon black stabilizes the material by protecting against UV resistance exposure, oxidation, and environmental aging.

The GEOWEB Geocell material has been laboratory tested to withstand continuous, direct UV exposure for periods up to 149 years without experiencing material degradation. In most applications, the GEOWEB system is buried, which further extends its service life by protecting it from prolonged UV exposure and environmental extremes. As a result, the GEOWEB system is considered a long-term stabilization solution with overall durability governed more by project design criteria and site-specific conditions than by limitations of the material itself.

Q6. How tall can a GEOWEB MSE Wall be?

GEOWEB Mechanically Stabilized Earth (MSE) Walls do not have a fixed height limitation, provided there is adequate space to accommodate the required soil reinforcement tiebacks. In accordance with FHWA and AASHTO design guidelines, reinforcement lengths typically extend 70% of the wall height.

For tall walls, the GEOWEB system is commonly used as a flexible fascia in combination with geogrid or geotextile soil reinforcement. The ultimate wall height is controlled by internal and external requirements including sliding, overturning, bearing capacity, and global stability. As with all MSE structures, proper drainage is critical to long-term performance.

When site constraints limit feasible tieback lengths, terracing is an effective solution. Rather than constructing a single tall vertical wall, the total elevation change is divided into multiple shorter, independently designed walls, reducing reinforcement lengths and improving constructability.

To receive a free project evaluation, please submit your project details at https://www.prestogeo.com/free-project-evaluation/.

The GEOWEB system has been successfully used on numerous high-wall projects over the years. Examples of these installations can be found in the Geosystems Project Gallery: https://www.prestogeo.com/gallery_presto/products/soil-stabilization/geoweb-retaining-walls/?type=casestudy

Q7. Do you perform overturning analysis and global stability checks for earth retention systems?

Yes, these analyses can be provided; however, the level of design support depends on the amount and quality of soils information available as well as the specific project needs. In all cases, it is recommended that an independent geotechnical engineer review and verify global stability analyses. Providing detailed information such as soil properties, groundwater conditions, seismic parameters, and overall site geometry allows for a more comprehensive and accurate evaluation.

For added flexibility, we offer a free MSE Wall Design Software for those who prefer to complete calculations internally. Alternatively, our experienced engineering team is available to assist with project reviews or through a project specific evaluation.

Request the free MSE Wall Design Software here: https://www.prestogeo.com/design/soil-stabilization/geoweb-mse-wall-software/

Q8. Do the GEOWEB Geocells come in different colors (e.g., green or blue) to blend with nature?

Standard GEOWEB geocell material is black, as 1 to 2% carbon black is added for UV stabilization to enhance durability and long-term performance.

For projects where aesthetics is a priority, particularly in earth retention applications, colored fascia options are available in a tan or green to better blend with the surrounding environment. To ensure long-term performance of the colored fascia panels, hindered amine light stabilizers (HALS) are added to protect against UV radiation and environmental exposure, helping to maintain structural integrity and appearance over the design life.

If a specific color requirement is desired, custom options may be considered depending on project requirements and quantities.

Let’s Keep the Conversation Going

We received even more questions than we could address during our webinar allotted time, and we appreciate the strong participation and engagement. If your questions weren’t addressed or if you’d like help with a specific project, we’d be happy to help and hear from you.

You can reach us directly using the contact information provided during the session, or email [email protected] to get started with a free project evaluation.