Geomembrane formulation

Q: We are specifying HDPE geomembrane for a critical project and noticed that GRI-GM13 only requires endurance testing “per formulation.” What is the definition of formulation and can we obtain Kiwa certification for a geomembrane produced using a known formulation? 

A: This definition can be found in section three (3) of GRI-GM13. It is as follows: “Formulation – The mixture of a unique combination of ingredients identified by type, properties and quantity. For HDPE polyethylene geomembranes, a formulation is defined as the exact percentages and types of resin(s), additives and carbon black.” Please note that manufacturers have complete traceability of their formulations for each roll produced. That written, Kiwa certification goes well beyond GRI-GM13. For starters, it requires ISO 9080 data, which is well beyond the scope of a Manufacturing Quality Control MQC specification.