In Limerick, the interaction between glacial till deposits and the underlying Carboniferous limestone creates conditions that demand careful slope evaluation. We see this regularly on sites near the River Shannon, where cut slopes in boulder clay can stand steep for a while, then ravel after prolonged rainfall. The analysis quantifies that uncertainty. A proper slope stability assessment gives the design team a factor of safety they can defend to the local authority, and it identifies the critical failure surface before excavation starts. The work involves site investigation, laboratory strength testing on undisturbed samples, and limit-equilibrium modelling using Spencer or Morgenstern-Price methods. Where the ground profile is complex, we complement the investigation with test pits to map the till-bedrock interface and confirm the depth of weathered zones that control the failure geometry.
A factor of safety of 1.3 on a Limerick till slope can drop below 1.0 in 48 hours if a perched water table develops after heavy rain — drainage is not optional, it is the primary stabilisation measure.
