A study was initiated to determine the accuracy with which the Extraction Procedures (EP), employed in the regulations promulgated under Section 3001 of the Resource Conservation and Recovery Act (40 CFR 26.124), simulates the leaching an industrial waste would undergo when codisposed with municipal refuse in a non-secure landfill. The simulation of the codisposal of municipal solid waste (MSW) with untreated industrial waste (IW) was initiated October 28, 1980. The 0.91 x 1.8 m cylindrical test cells were designed to simulate sanitary landfill environments. The 5 types of industrial waste were oil reclaiming clay, petroleum refinery incinerator ash, paint manufacturing sludge, solvent refining sludge, and tannery waste. Fifteen test cells were loaded providing triplicate samples of each IW leachate. The increase in concentration of the metals in the blow MSW-IW is compared to the change in concentration produced in the EP extract. When the published EP concentration criteria (100 time primary drinking water standards) for the specific metals was exceeded, the test cells also showed a concentration that exceeded the criteria. The EP concentrations are generally lower than the concentration of the same constituents from the same wastes in the test cells.