Equivalent Design and Evaluation of the Liner System for a Hazardous Waste Landfill Vertical Expansion

An alternative liner system utilizing geosynthetic clay liner (GCL) in lieu of the permitted compacted clay liner (CCL) was proposed for a vertical expansion at a hazardous waste landfill sitting over an existing unregulated landfill. An assessment was conducted to demonstrate that the proposed system is technically-sound and effective and meets all federal and state rule requirements. Two critical equivalency assessment items including (i) steady state solute flux and (ii) chemical adsorptive capacity and solute breakthrough time were evaluated and are discussed in this paper. Based on the evaluations and discussions, the proposed alternative GCL system is equivalent or superior to the currently permitted CCL system and is capable of preventing the migration of hazardous constituents into the groundwater or surface water at least as effectively as the CCL system.