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“Or Equal” Substitutions in Geosynthetics: Evaluating the Contractor’s Proposed Alternative Amidst Global Supply Chain Disruptions & Rising Costs

truck driving over sand filled geoweb road

As supply chain issues and project delays continue to wreak havoc in the global geosynthetics industry, Presto Geosystems has prepared this “reboot” of our tips for evaluating “or equal” substitutions to help you navigate the decision-making process when confronted with a proposed alternative geosynthetic product.

According to a recent special feature article from Geosynthetic News Alerts (GNA), more oversight and diligence is needed—now more than ever—as deceptive products and inferior raw materials continue to find their way into global markets.

According to GNA “Distributors and installers that place orders in good faith—particularly with overseas vendors—may wind up with rolls of geosynthetics they can’t use, and no wriggle room in compressed delivery timelines to find alternatives or otherwise rectify errors.” To protect against this, GNA goes on to emphasize the importance of vetting geosynthetics suppliers to maintain quality metrics. In light of this, Presto offers this reboot of our five tips for evaluating “or equal” substitutions to help you keep your project on the path to success amidst the chaos.

Tip #1: Review Product Datasheets Closely (Be Wary of Disclaimers)

Many design professionals tend to focus on the numbers shown on a product datasheet and may even have an implicit trust in the information provided. Unfortunately, some geosynthetics manufacturers and distributors will use this to their advantage.

After an initial review of the product data, you will have a sense of whether the product at least appears to meet the project specs on the surface. However, it is imperative to dig a little deeper. Pay close attention to any disclaimer language in the fine print at the bottom of the page.

Disclaimers that include statements such as “…specifications may change without notice” are a red flag.

Manufacturers who invest in quality assurance programs typically don’t need to provide this type of disclaimer, and are willing to stand behind their published product data.

geocell disclaimer warningTip #2: Learn More About the Product Manufacturer

Starting with a few simple questions, you can obtain a sense of whether or not the product is “tried-and-true,” relatively new, or entirely unproven. Below are a few questions that can help you learn more.

  • Who actually manufacturers the product? This is particularly important when working with organizations that claim to be both a distributor and manufacturer of geosynthetics products. It is important to understand specifically which products they make versus those they distribute or offer under private label agreements (or OEM license agreements). Most importantly, remember that just because a company’s logo is on a product datasheet does not mean they are the manufacturer. Only accept product datasheets with the manufacturer’s information on it—not the distributor!
  • Can the manufacturer provide project references or case studies demonstrating the proposed substitution has been successfully used on similar projects elsewhere?
  • Can the manufacturer provide calculations demonstrating the proposed alternative will meet design objectives?
  • Can the manufacturer provide technical assistance during installation and provide support if unexpected challenges should arise during construction?

Tip #3: Look for Markings of Product Quality & Manufacturer Integrity

Indications of product quality such as the CE marking and ISO certification are useful in establishing an increased level of confidence that the manufacturer holds product quality and data integrity in high regard.

  • UKCA CE ISO CertificationsCE Mark – The CE Mark is an EU-mandated regulatory mark declaring the manufacturer’s product data is trustworthy and must be carried on products sold in the European market. While not required for geosynthetic products sold outside of the EU, it can provide a quick “gut check” as less reputable manufacturers will have difficulty obtaining this mark. The CE mark should include the number of the certification body beneath it, and the manufacturer should be able to provide a valid Certificate of Conformity of Factory Production Control upon request. The CE certificate will identify which products are included, as well as the location where the products were manufactured.
  • ISO 9001 Certification – For a manufacturer, obtaining certification under the ISO 9001 standard requires a significant commitment (and investment) in establishing and maintaining a comprehensive quality management program. Comprised of quality management procedures (QMPs), the program must consider every step of the production process, from the receipt and handling of raw materials to the finished product. Manufacturers who are ISO-certified should be able to provide a valid Certificate of Registration upon request. The ISO certificate will identify the name of the manufacturer, certificate number, certifying body, and a statement indicating the manufacturer’s quality management system complies with the requirements of ISO 9001 for the specific products of interest.
  • Certificate of Analysis (COA) – Implementing a robust ISO-certified quality management program typically requires continuous quality assurance and quality control testing in order for produced goods to be approved for release from the manufacturing facility. As part of this testing, a Certificate of Analysis, or COA, should be available for all manufactured lot numbers. Accordingly, reputable geosynthetics manufacturers should be able to provide COAs for products that ship to your project site, thereby providing documentation that the goods received were tested and approved in accordance with their ISO-certified quality management program.

Tip #4: Get Third-Party Data

This typically begins with a request to the contractor or manufacturer to provide third-party data to confirm the results are consistent with the product datasheet, and that the proposed substitution will perform as advertised. With manufacturer-provided data, it is important to verify that the results are from an accredited third-party laboratory.

If you are not comfortable with the data provided, or have lingering doubts, request that the contractor provide representative samples of the material for further inspection and testing. Provided the project budget allows, an ideal laboratory test program would include analysis of the samples of the proposed substitution as well as the originally-specified product. Including the originally-specified product as the baseline for comparison allows for a comprehensive evaluation of the results, and ultimately supports in making a well-informed decision.

Tip #5: Prepare a Summary of Your Evaluation

Before responding to project stakeholders, it can be helpful to prepare a summary of your evaluation laying out your findings and providing the rationale behind your assessment. We’ve prepared a checklist and product scoring sheet incorporating the considerations above that can be used as a starting point for completing your evaluation. You can download this form using the link below.

Download the Checklist >>


Read “The Significance of High-Quality Standards” >>