By definition under RCRA, hazardous wastes are classified as which type of waste?

Hazardous wastes, according to the Resource Conservation and Recovery Act (RCRA), are primarily classified as solid wastes. This classification encompasses not just the physical form—the term "solid" includes not only solid materials but also liquids and gases that are deemed hazardous. The important aspect of this classification is that it is based on the characteristics of the waste that make it hazardous, such as being ignitable, corrosive, reactive, or toxic, rather than strictly on its physical state.

Thus, even though hazardous wastes can exist in various forms (liquids, solids, and sludges), they are categorized under the broader definition of solid waste for regulatory purposes. This ensures comprehensive management and compliance protocols are in place, as recognizing hazardous waste, regardless of its actual state, allows for appropriate handling and disposal methods to mitigate potential environmental and health hazards.