Lead-contaminated soil disposal in non-hazardous waste landfills - Groundwater effects and policy implications

Lead-contaminated soil that fails the Toxicity Characteristic Leaching Procedure (TCLP) test must be managed as hazardous waste under the Resource Conservation and Recovery Act (RCRA) and disposed in Subtitle C landfills. We examine the actual risk to groundwater from the management and disposal of lead-contaminated soil in non-hazardous waste landfills. Lead concentrations in leachate-affected groundwater were modeled using EPA's Monte Carlo Composite Model for Leachate Migration with Transformation Products (CMTP). Simulated leachate concentrations were based on Synthetic Precipitation Leaching Procedure (SPLP) and TCLP tests of soil from lead-contaminated Superfund sites. Receptor well lead concentrations were less than the drinking water standard (0.015 mg/L) in 98.5% of the SPLP scenarios, and 96% of the TCLP scenarios. These were more protective than the level EPA used to justify a proposed conditional exclusion from the RCRA hazardous waste program for architectural debris containing lead-bearing paint, allowing disposal of such debris in non-hazardous waste landfills. Since the risks to groundwater from lead-contaminated soil disposal are less than those from architectural debris, EPA should allow lead-contaminated soil that fails the TCLP to be disposed in nonhazardous waste landfills. This would reduce the costs of its management and encourage greater remediation of lead soil hazards.