Physical modelling of in-ground waste repository capping systems Available to Purchase

This paper describes a series of geotechnical centrifuge tests carried out to investigate aspects of landfill capping system performance, in the context of a low-level radioactive waste disposal site. The effects of the basic cap geometry (sloping or flat) and the subsidence pattern imposed as the underlying waste degrades (ramp or step, i.e. slope or displacement discontinuity) are shown to influence cap performance. The effect of moving the toe of a sloping cap outside the landfill subsidence zone, thereby increasing the depth of inert fill below the cap, is also shown to be effective in limiting the displacements transmitted to the resistive layer. Analysis of the runoff from sloping capping systems shows that if the resistive layer fails, there is the potential for the infiltration rate through the cap to increase from near zero to almost 100% of the incident rainfall.