Treatment alternatives for lead impacted media: Case studies

Lead impacted media resulting from past waste management practices was detected at a lead casting facility, two mirror manufacturing plants, and a municipal landfill. Leachable lead concentrations prior to treatment ranged from 10 milligrams per liter (mg/l) in a mirror waste pile to 900 mg/l at a lead casting facility. Cement stabilization and the application of a chemical treatment process solution were evaluated as treatment alternatives for each facility based on the cost of treatment and disposal, and time limitations. Cement stabilization was used at two of the facilities and the application of a chemical treatment process solution was used at the other two facilities. The evaluation of treatment alternatives began by characterizing the waste at each facility and performing treatability studies to determine the minimum ratio of cement-to-waste or the minimum concentration of the chemical solution needed to render the lead impacted waste non-hazardous. Cement stabilized wastes were recycled for reuse as fill for the construction of a parking lot at one facility and as the sub-base of a new road at another facility. The use of a chemical process solution permitted on-site treatment and off-site disposal of non-hazardous waste at a RCRA Subtitle D landfill. Following treatment by either cement stabilization or chemical treatment process, leachable lead concentrations were reduced below federal regulatory levels according to the Resource Conservation and Recovery Act (RCRA) maximum allowable concentration limit of 5 mg/l lead (D008) by the toxicity characteristic leaching procedure (TCLP).