Sanitary landfills operate by layering waste in a large hole. There are different levels of layering of waste to facilitate the decomposition of the materials as well as trap toxic gases released from the process. The layers are made in such a way that the bottom part has the smallest volume, with the top part taking the bigger volume to avoid collapsing of the land.

The first layer is the liner system. This is the lowest layer and the first one used in laying a foundation for the sanitary landfill. The process entails the application of compact and well dense clay to prevent the seeping in or out of liquids. It is for this reason that this clay is completely impervious.

This modernized type of sanitary landfill is also fitted with high-density plastic which is applied on top of the clay for reinforcement. This engineering design is to make certain there is no room for the penetration of liquids, thus preventing contamination of the underground water.

The second layer is the drainage system. The drainage system takes care of the liquid produced from the decomposition of some waste materials. Due to the toxicity of this liquid, it should not seep past the liner layer. The drainage layer aids in draining away this liquid to avoid it from getting close to the liner system. Moreover, rainfall and snow may also seep from the top surface to the landfill and also needs to be drained away.

These liquids may contain contaminants from the waste materials that can corrode the liner system and contaminate the soil and water below the landfill. In reducing this risk, the sanitary landfill is fitted with perforated pipes on top of the liner layer to collect all the liquids that find their way to the bottom of the landfill through leaching, thus the name leachate. The plumbing system then directs the leachate to treatment plants to undergo treatment for reuse.

The third layer is the gas collection system. In the same way that liquids are produced, gases are also released through natural processes. Methane is the most common of these gases. Methane is a gaseous hydrocarbon that is very volatile as well as toxic, and thus, when released into the atmosphere, it contributes to global warming and can harm the overall environmental health.

There are, therefore, extraction pipes in this layer that trap methane gas and transport it to treatment plants to treat the gas and thereafter, use it to produce electricity and to power various processes.

The fourth layer contains the trash itself. This is the largest layer and is also the topmost. Periodically, trash from various sources is brought in by the various garbage collection companies and dumped in this layer. To avoid taking too much space, the garbage disposed of is compacted on a daily basis.

Once this has been done, a layer of compacted soil is applied to the surface of the sanitary landfill. Soil does a good job of containing bad smells and the growth of harmful microorganisms such as pests and flies. Also, the compact soil keeps away windblown debris.