Much of the waste produced in cities and towns is deposited in landfills. But as waste collects in landfills, it can mix with water and other liquids to produce leachate, which can then leak into groundwater and pollute local water supplies. To prevent environmental contamination, waste companies install landfill liners in the bottom of landfills during construction.
Several variables should be considered when selecting and installing landfill liners, but the single biggest priority is preventing or minimizing the escape of leachate from the landfill. Landfill liners are generally composed of a layer of compacted clay, which is then overlaid by either an HDPE geomembrane (high-density polyethylene) or an LLDPE geomembrane (linear low-density polyethylene).
Additional factors should be considered when selecting landfill liner material. One particularly challenging factor can be damage of the geomembrane during installation. The geomembrane must be able to resist tearing and puncturing during installation in the landfill.
One other factor to consider is the steepness, or slope, of the sides of the landfill. To maximize available acreage and dispose of as much material as possible, waste disposal companies want to dig their landfills as deeply as possible. However, a deep landfill generally means steeper landfill slopes; this can present a number of challenges for landfill liners, such as more challenging installation, more difficulty adhering to the surface of the landfill, and increased shear tension due to the weight of the waste in the landfill against the steep slope. This is one reason LLDPE geomembranes, which offer greater tensile strength and anti-tear properties, are sometimes used. In addition, textured geomembranes as opposed to smooth geomembranes are sometimes utilized to help the liner find traction against the slope of the landfill.
Many governments have set forth guidelines or legal requirements for landfill liner manufacturers by way of regulatory bodies, such as the Environmental Protection Agency in the United States. The applicable regulatory agency or agencies in your area can help determine local requirements for landfill liner construction and installation.
