There is a large reliance on piezometric cone penetration testing (CPTu) in the tailings industry to define key features and strength parameters for assessing the stability of tailings storage facilities (TSFs). The current methods available to analyse the CPTu data, specifically regarding residual undrained shear strength ratio (USSR), are largely based on correlations and assumptions and therefore contain pronounced limitations. To define these limitations CPTu data was interpreted using three different methods of determining residual USSR and the results compared. The methods included those developed by Roberston (2022) [3], Been and Jefferies (2016) [2] and Olsen and Stark (2002) [1]. The limitations were defined and a hybrid method incorporating all three were employed to determine and apply residual USSR properties to stability models. The results of the CPTu interpretations were used to discretise tailings profiles to outline the potentially saturated weaker layers. Key assumptions, such as the location of the phreatic surface, could be adjusted to better align with the data, as a result thereof. Residual USSR values were applied to the identified layers based on the hybrid method. A series of sensitivity analyses were completed, using limit equilibrium, to determine the impact of using the hybrid method. The focus was mainly on the assignment of the residual USSR to the layers that are either grouped or independently included in the model. The results indicated that the inclusion of the potentially saturated weaker layers had a pronounced effect on the shape and daylighting location of failure plane, influencing the global factor of safety.