What are the three categories of bottom liners?

The correct categorization of bottom liners includes natural liners, geosynthetic clay liners (GCL), and geomembranes.

Natural liners, such as clay, are often used due to their ability to provide an impermeable barrier that helps prevent leachate from contaminating the surrounding environment. These liners benefit from the natural properties of certain soils that can effectively seal off the landfill contents.

Geosynthetic clay liners (GCL) combine natural clay with geosynthetic materials, offering a more compact and efficient option for preventing fluid migration. They are designed to enhance the sealing capabilities of natural clay while being lighter and easier to install, making them particularly useful in landfill applications.

Geomembranes are synthetic liners made from materials like polyethylene and are designed to serve as impermeable barriers. They provide a reliable solution to ensure that leachate and hazardous materials do not escape from the landfill.

Each of these categories plays a critical role in landfill design and operation, contributing to the overall environmental and operational safety of landfill practices. The other options do not fully encompass the standard terminology and classifications used for bottom liners in waste management, which is why they are not as accurate.