Protective Layer Design in Landfill Covers based on Frost Penetration

Abstract

We develop a design procedure to determine the minimum thickness of a protective soil layer over a barrier layer in a landfill cover design. The procedure equates the minimum thickness of the overlying protective layer to the predicted extreme freezing-events depth that may occur in the landfill design life. This procedure is applicable to Resource Conservation and Recovery Act Subtitle C hazardous waste landfills and any landfill designed to encapsulate hazardous waste from the environment for long periods of time. This procedure was formulated by the Uranium Mill Tailings Remedial Action Project’s Technical Assistance Contractor to protect radon and infiltration barriers from degradation over a 200-year minimum design life. The procedure uses common soil parameters, a personal computer version of the modified Berggren equation, and site-specific daily maximum-minimum temperature data compiled for a minimum of 30 years to compute frost depths. The computed frost penetration magnitudes are then used with a Gumbel extreme-value probability distribution to predict frost depths for recurrence intervals corresponding to a design life that exceeds the record of observed data.