What are the five layers that a landfill needs to be safe?

1. Liner System: This is the bottommost layer of the landfill and consists of a synthetic or natural material that prevents the leachate (the liquid that seeps through the landfill) from contaminating the groundwater. The liner system usually includes a layer of clay, a geosynthetic membrane, and a drainage system.

2. Leachate Collection and Removal System: This system is designed to collect and remove the leachate from the landfill. It usually consists of a network of pipes and sumps that are connected to a treatment facility.

3. Gas Collection and Control System: Landfills produce methane gas as a result of the decomposition of organic waste. This gas can be harmful if it escapes into the atmosphere, so a gas collection and control system is installed to capture and utilize or burn the gas.

4. Daily Cover: Each day, a layer of soil or other suitable material is placed over the waste to minimize odors, control vectors (such as pests), and prevent the waste from being exposed to the elements.

5. Final Cover: Once the landfill is full, it is covered with a final layer of soil or other suitable material to seal it and prevent the waste from coming into contact with the environment. The final cover may also include a layer of vegetation to promote stability and minimize erosion.