Written By: Michael Dickey, P.E., Director of Presto Geosystems
Like many other industries, geosynthetics manufacturers are navigating the rapidly evolving landscape of new per- and polyfluoroalkyl substances (PFAS) regulations. However, in the case of geosynthetic products, an interesting and seemingly paradoxical question emerges: Is it possible that the same products that have been designed to solve complex environmental problems, and even contain pollutants, could also be a possible contributing source of PFAS?
In this article, we explore this question and discuss the historic role of polymer processing aids (PPAs) in the production of geosynthetics.
What Does Intentionally vs Unintentionally Added PFAS Mean?
Since the discovery of PFAS in the 1930s, these compounds have been widely used in manufacturing operations worldwide—both intentionally and unintentionally. In a recent article published by the American Bar Association, the concept of intentional versus unintentional use of PFAS is discussed, and in the case of the latter, the use of fluorinated PPAS used in thermoplastics processing is highlighted as a well-known unintentional PFAS source. How this concept relates to traditional geosynthetics manufacturing is discussed further below.
Eliminating Polymer Processing Aids (PPAs) from Geosynthetics
Production of geosynthetic products such as geogrids, geomembranes, and geocells commonly involves sheet extrusion of raw materials as an initial step in the manufacturing process. The raw materials typically comprise various pelletized thermoplastic materials (e.g., polyethylene, polypropylene, etc.) that have been engineered by resin suppliers and plastics compounders to incorporate ingredients for improved processability. To achieve this, additives known as polymer processing aids (PPAs) are incorporated into the raw materials. PPAs may be incorporated into the base resin materials, additives, or “master batches,” in different proprietary formulations intended to meet manufacturers’ needs. Up until recently, fluorinated PPAs, a potential source of PFAS, were the go-to standard for PPAs.
By incorporating PPAs into the raw materials, faster extrusion speeds can be achieved without increasing resin processing temperatures, thereby limiting energy consumption and reducing operating costs. Additionally, in the case of products where a smooth finish may be required, such as smooth geomembrane liners, PPAs eliminate “melt fracture,” a phenomenon caused by excessive shear stress on the molten resin that leads to undesirable roughness in the finished product.
Accordingly, with increased awareness of the potential presence of integral fluorinated PPAs in raw materials, many geosynthetics manufacturers are proactively conducting due diligence efforts of their own to identify and eliminate fluorinated PPAs from their products. This entails vetting of raw materials to ensure no product ingredients contain added PFAS from suppliers, and where necessary, adjusting product formulations to eliminate PFAS-containing ingredients.
Presto Geosystems, world-leading geocell manufacturer and inventor of the GEOWEB® Cellular Confinement System (CCS), recently conducted similar efforts, and confirms the product formulation for GEOWEB Geocells does not contain any intentionally added per- and polyfluoroalkyl substances (PFAS), and based on this understanding, GEOWEB Geocells are not expected to pose a risk of release of PFAS compounds into the environment.
Therefore, in returning to the original question, could geosynthetics be a possible contributing source of PFAS to the environment? The answer is yes…maybe. Engineers and project owners are encouraged to do their own due diligence when exploring different geosynthetics products, and when necessary, obtain a written statement from the manufacturer confirming they have conducted due diligence to confirm their products do not contain any intentionally added PFAS, and are therefore not expected to pose a risk of release of PFAS compounds into the environment.