Seismic analysis of solid waste landfills

Specific provisions are included in Title 40, Part 258 (RCRA Subtitle D) of the 1991 United States (U.S.) Environmental Protection Agency (EPA) regulations governing municipal solid waste that dictate a new landfill unit or lateral expansion cannot be located in seismic impact zones unless the containment structure can withstand earthquake accelerations. Through the use of seismic response analyses on three existing landfill sites, two state-of-the-art landfills in New York State (NYS) and one existing landfill in Massachusetts, the authors noted that the selection of dynamic material properties and a representative earthquake motion are potentially the most important decisions a practitioner faces in seismic response analysis. Results of seismic response analyses by the authors and other researchers and practitioners are examined to evaluate input motion propagation with special emphasis on input motion frequency. Seismic response of the waste fill/foundation systems was assessed with 'WESHAKE', which was adapted by the U.S. Army Corps of Engineers from the original 'SHAKE' model (Schnabel et al., 1972). Multiple simulations were conducted with two U.S. west coast and two eastern North American earthquakes accelerograms. The authors found that peak bedrock accelerations alone, are inadequate to properly characterize seismic response. As exhibited by these simulations, the model predicted a damping of the high frequency eastern North American motions and an amplification of the low frequency western U.S. motions.