Abstract Rock salt is particular impermeable to gases and liquids. The solution-mining method provides the means for the creation of large storage capacities at economic costs. The geotechnical behaviour of rock salt is well-known with sufficient details for dimensioning purposes. Due to its favourable geomechanical properties, halite remains stable over long periods of time without support. However safety analysis has to be carried out in each case based on specific data. Such an analysis comprises engineering geological study of the site, laboratory and in-situ measurements. Model calculations are essential. The study of uncertainties is fundamental part of the confidence building. The uncertainty of parameters (geometry, material behaviour, initial conditions, loading) given in a validated model can be expressed by a probability density function, but the model uncertainty is not a stochastic resp. probabilistic attribute. It can be described as a lack of dependability of a model to predict structural response assuming precisely defined parameters, Therefore the objective of model validation exercise must be the demonstration that a model is sufficiently accurate to predict structural response or migration of toxic particles by knowing the logic of idealization or justification of simplification (conservatism).