Abstract In recent years the climb in demand for gas storage space has led to the expansion of existing and construction of new cavern storage facilities. More projects are currently under discussion. The planning and construction of gas caverns in West Germany has been the state of the art for many years. This is becoming reflected on an international scale, as evidenced by the increasing foreign orders for planning and construction work. This paper deals in some detail with certain innovative technical developments, including newly developed methods for testing correct makeup torque as well as the tightness of pipe joints from the inside to the outside with a test gas. Moreover, insitu large-scale tests in the areas of "stability and convergence behaviour" as well as "cavern sump sealing" and their results to date are presented. Operational experience with gas caverns is now available for up to 2 0 years. During this period of time, some repair work to subsurface technical installations was necessary. The planning and execution of this work is described.