It is carefully reviewed by health and environmental officials who issue the appropriate permits. Safety is the primary concern Today's landfills include multiple safeguards to contain wastes and isolate them from surrounding water and soil. In many cases, for example, such safeguards involve a protective liner to prevent filtration. These liners may be made of compacted clay or impermeable materials such as plastic. When clay is used, the layer may be as much as 10 feet thick.
Drainage systems are another common feature.
Monitoring wells around the perimeter of the landfill allow technicians to check groundwater quality and detect contamination. Each day, landfill operators must handle truckloads of trash. To assure proper management, such wastes are generally unloaded at only one designated area. Walls of dirt known as berms, built around most landfills, prevent unloaded wastes from being blown by the wind and shield them from view. Once trash has been deposited, it is spread and crushed by a bulldozer or compactor.