Refers to laboratory procedures that use water, acids, bases, organic solvents, salt solutions, or other liquids to estimate the types and concentrations of contaminants that will dissolve out of a solid waste or another solid sample. Leaching procedures are useful in predicting whether the dumping or burial
of a solid material could potentially release problematic levels of contaminants into groundwater, surface waters, or other natural environments. Leaching procedures include batch, sequential batch, serial batch, and column methods. Some batch leaching tests, such as the toxicity characteristic leaching procedure (TCLP), are used in regulations to identify solid and liquid wastes for the toxicity characteristic of hazardousness.