Solid waste landfills serve as municipal waste containment facilities. Presently landfills are
required to accommodate as much volume of waste as possible while isolating the waste from
surrounding air soil and ground water. With the intention to provide sufficient space for the
increasing waste volumes modified landfill designs have been implemented which incorporate
designs with steep side slopes. Although the National Norms and Standards for Disposal of Waste
to Landfill provide the minimum requirements and state that alternative design layouts for
landfill slopes exceeding 1H:4V may be considered the new implementation could increase the
risk of landfill instability (Department of Environmental Affairs 2013a Emery 2014).
Research has shown that instability problems may be associated with shear failure (Russell et
al. 1998 Kim 2006 Feng et al. 2010 Duffy 2016). In such cases the safety of these
containment facilities depends on the shear strength properties of the landfill boundary
conditions and construction materials. As a result proper understanding of shear strength
parameters is essential in ensuring safe designs.
