"A study was initiated to determine the accuracy with which the U.S. Environmental Protection Agency (EPA) extraction procedure (EP) simulates the leaching of an industrial waste when codisposed with municipal refuse in a nonsecure landfill. The EP is used in the regulations promulgated under the Resource Conservation and Recovery Act. Simulated codisposal of industrial and municipal waste was initiated October 28, 1980. Cylindrical test cells 0.91 x 1.8 m were designed to simulate sanitary landfill environments. The five types of industrial wastes tested were oil reclaiming clay, petroleum refinery incinerator ash, paint manufacturing sludge, solvent refining sludge, and tannery waste. Fifteen test cells were loaded to provide triplicate samples of each industrial waste leachate. Each week, all cells received an 8.4-liter addition of deionized water, the equivalent of 1.27 cm of infiltrated rainfall. Leachate samples were collected from beneath the municipal waste and the municipal/industrial wastes each month. Seven inorganic parameters were measured during five sample periods for leachate collected below both wastes. The metal concentration from the leachate collected below the municipal/ industrial waste was compared with that produced in the EP extract. When the EP extract concentration of a specific metal exceeded the concentration criteria (100 times the National Interim Primary Drinking Water Standards), the test cells also showed a concentration that exceeded the criteria. But EP concentrations were generally lower than those for the same wastes in the test cells, and very little quantitative relation was shown between the EP and the test cell results."