Did you know that a landfill is not the same as a dump? A dump is just an open hole where garbage is buried. A landfill is more carefully designed and is built so that the garbage is isolated from the surrounding environment.
Landfills are not the perfect ending point for all of our garbage. There are some problems with landfills, including:
Landfills are getting full.
Liners in landfills have been found to leak which can result in contamination of groundwater.
Landfill gas or methane, is generated as wastes break down. Methane is a potent greenhouse gas.
At the Landfill
In order to understand some of the problems that can occur with a landfill, it is important to know how a landfill is set-up. Below is a picture of a cross-section of a landfill.
The arrows in the figure above show the flow of leachate. This image is available at: HowStuffWorks.
The major problem associated with landfills is trying to keep the trash from coming in contact with the environment. The purpose of the bottom liner is to prevent the garbage from coming into contact with the groundwater. However, there is a chance that the liners could leak and contaminate groundwater.
Trash is compacted in landfills to maximize the garbage that they can hold but many current landfills are getting full.
Another problem is that the landfill must remain dry to minimize the amount of leachate that is generated from the landfill. Leachate is the water that becomes contaminated by seeping through all the garbage. If this is not properly managed or leaks through a landfill liner, it can pollute our waterways, coastal areas and ground water. Landfills usually have storm drainage systems to allow leachate to drain from the system into a contained collection pond. Leachate that escapes contaminates the surrounding environment.
Methane gas is also a problem at landfills. Landfills are airtight and so the waste breaks down anaerobically (in the absence of oxygen). One of the by-products of this decomposition is methane. Methane is a greenhouse gas. Greenhouse gases contribute to climate change.
When a landfill is full, it is covered with a cap and then covered with soil. Even once a landfill is closed there is still environmental risk.