More than 70 underground mined caverns for LPG storage have been constructed in the USA from 1950 to the early 1980’s. Several decades later, a revamping, or at least a review of some of those underground facilities becomes necessary regarding their long term stability and hydrogeological integrity.
A specific approach has been developed for evaluating the geomechanical stability of such old underground storages. This paper presents this methodology. Requirements for hydrogeological integrity are briefly presented. The article focuses on geomechanical stability. The different phases of the studies from the definition of a complementary site investigation to the realization of analytical and numerical calculations are detailed. Finally, the evolution across time of the best practices for underground storage concept design is presented.