Landfill Liner and Cover Systems-The Geomembrane
A geomembrane is an essentially impermeable membrane used with foundation, soil, rock, earth or any other geotechnical engineering-related material as an integral part of a structure or system designed to limit the movement of liquid or gas in the system.
liner system exposed on the side slopes.
Application of a geo-membrane liner above a low permeability clay foundation.
Geomembrane liner seams are sealed in the field with a high
temperature "wedge weld."
Vacuum testing one of several ways that seams between geo-membrane panelsare tested.
A leachate collection layer is placed above the geomembrane.
The selection of a particular geomembrane polymer in a landfill liner system or cover system is a task for the landfill design engineer. One of the factors that the design engineer must consider is the projected service life of the particular geomembrane polymer selected, as the service life of different geomembrane polymers can vary widely. Other factors to consider are typical mechanical properties to help ensure veneer stability as well as the durability of the geomembrane.
The geomembrane used in the landfill liner systems must be 60 mils (0.06 inches) thick and must be made of a material (such as high density polyethylene (HDPE)) that is extremely low in permeability. The material must also have chemical and physical characteristics that are not adversely affected by the placement of waste or by contact with leachate.
Linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) are materials typically specified for geomembranes in solid waste landfill cover systems. A geomembrane barrier used in landfill final cover system must be a minimum of 40 mils thick if comprised of LLDPE or a minimum of 60 mils thick if it is comprised of HDPE. The 60 mils minimum thickness for HDPE geomembranes is to achieve proper field seams.