Landfills are created by digging holes in the ground and lining them with plastic waterproof liners (HDPE). The plastic liners prevent trash juice (leachate) from seeping into the surrounding soil and groundwater.
Landfills are a result of the Resource Conservation and Recovery Act (RCRA) and are regulated under RCRA Subtitle D (solid waste) and Subtitle C (hazardous waste) or under the Toxic Substances Control Act (TSCA).
As of 2022, there are over 2,600 landfills across the U.S.A. that handle municipal solid waste.