Part 1: How to Determine HDPE Geomembrane Thickness

Ever since polymers were first developed as a construction material, engineers have created product variations that make work easier and can be tailored to project needs. Polyethylene was first discovered in 1933 by Fawcett and Gibson using a high-pressure technique. The high-pressure process works at temperatures above 250 degrees Celsius and pressures between 1000 and 3000 atm. The most widely used types of PE are High Density Polyethylene (HDPE), Low Density Polyethylene (LDPE) and Linear Low Density Polyethylene (LLDPE). Knowing these types is the first step in choosing the right HDPE geomembrane thickness.

The significant difference between HDPE and LLDPE lies in their density. HDPE is the strongest, most durable and least flexible of the polyethylene types. HDPE also withstands temperature changes well. LLDPE, on the other hand, has better tensile strength than LDPE of the same density, and it is the most flexible of the polyethylene types. LLDPE is generally used where high strength and high resistance to punctures or tears are required.

40 mil (1 mm) HDPE Geomembrane Liner

The most common HDPE geomembrane liner thickness is 40 mil (1 mm), which offers good strength and impermeability at a lower cost. HDPE geomembrane liners of this thickness are usually used for applications such as raw water storage, rainwater storage, agricultural waste containment and aquaculture ponds.

Although this HDPE geomembrane liner has lower strength and puncture resistance than thicker options, the thinner liner has several advantages: it is cheaper, easier to transport and easier to install because it comes in longer rolls.

40 mil (1 mm) HDPE geomembrane liner is usually used for agricultural ponds and other relatively non-critical applications. In these applications, the 40 mil (1 mm) HDPE geomembrane liner serves as a waterproof layer that prevents the pond contents from seeping into the surrounding environment.

60 mil (1.5 mm) HDPE Geomembrane Liner

Another common HDPE liner thickness is 60 mil (1.5 mm). The 1.5 mm thickness has higher physical strength and lower permeability (the ability of a material to let fluids pass) than the 40 mil (1 mm) variant. Being thicker, it also offers better weather resistance, making it more suitable for applications that are continuously exposed to the sun.

Some projects must comply with the rules of regulatory bodies such as the Environmental Protection Agency (EPA), which set a minimum thickness for the HDPE liner to be used. For example, for HDPE liners in non-hazardous waste landfills, the EPA requires a minimum nominal thickness of 60 mil (1.5 mm). This requirement helps reduce the potential for tears or punctures.

In addition, designers will specify a 60 mil (1.5 mm) or thicker HDPE liner for applications that require greater liner strength or lower permeability (the ability of a material to let fluids pass). The level of risk must also be considered when choosing a geomembrane. For example, ponds holding B3 (hazardous and toxic) waste or waste containing heavy metals usually use a thickness of 80 mil (2 mm).