What is a Landfill?
Landfills are areas where waste materials are sent, and then buried underground. Precautions are taken during this process to prevent the waste from touching any groundwater and eventually polluting it. Landfills have remained pretty much unchanged since their first recorded presence. Minoan Cretans in Ancient Greece would dump Waste into open pits and bury it later, which provided an early example of a landfill. The first sanitary landfill, resembling the landfill of today, was established in Fresno, California, in 1937.
A usual landfill starts in the form of a hole dug in the ground; it is filled with compressed soil or liner. The hole is filled over time and as more waste is added the landfill becomes more of a pile. When it hits the point that it can no longer take waste, the landfill is sealed. A properly closed landfill includes a “cap” that prevents flowing water and humidity into it.
Types of Landfills
- Municipal Solid Waste (MSW) Landfills: MSW landfills are the most typical types of landfills and are used for disposal of household waste.
- Industrial waste landfills: These landfills have industrial and institutional waste disposed of.
- Hazardous Waste Landfills: These sites receive specific Waste that needs to be treated carefully because it has the possibility to be toxic if not carefully disposed.
Waste breaks down within a landfill, and generates gas. Landfill gas contains many gases. Methane and carbon dioxide comprise between 90 and 98 percent of landfill gas. Nitrogen, oxygen, ammonia, sulfides, hydrogen and various other gases are found in the remaining 2 to 10 percent. The magnitude of these gases depends on the form of waste present in the landfill, landfill size, oxygen content, moisture content and temperature. While output of these gasses typically peaks in five to seven years, a landfill will continue to generate gas for over 50 years. This gas emission of landfills shows the importance of a portable multi-gas analyzer.
Gasses from landfills affect climate change. The main components are CO2 and Methane, which are both greenhouse gases. Methane is a much more powerful greenhouse gas in the atmosphere, for each molecule having twenty-five times the effects of a carbon dioxide molecule. Nevertheless, methane itself forms less of an atmospheric composition than carbon dioxide.
How are people exposed?
People at the landfill or in their nearby districts can be exposed to landfill gases. Landfill gasses can migrate over or beneath ground from the landfill. Gases can pass into the ambient air through the landfill surface. When in the air, the winds will bring the landfill gases to the city. Odors from routine landfill operations indicate gasses move above ground. Ammonia and hydrogen sulfide are responsible for the majority of landfill odors. Gasses may also migrate underground through the soil and reach homes or service corridors on or adjacent to the landfill; where Methane and carbon dioxide for instance, could displace oxygen. Methane is also highly flammable and concentrations have often caused exceeding of indoor explosive levels.