Underground oil storage facilities in Japan

In Japan, three underground crude-oil storage facilities with a total capacity of 5 million kl are under construction as a chain of the national oil storage project. Because the NATM method was used in this project, we applied a systematic work control system, consisting ofin situ measurements and engineering geological observations, including an original rock-mass classification system. The classification system used can be slightly modified depending upon site-specific geological conditions and the purposes of the facilities such as, i.e., an artificial water sealing system.