A novel method of construction of a deep underground cavern for storage of liquefied petroleum gas

One of world's deepest underground liquefied petroleum gas (LPG) storage caverns and South Asia's first such project has been constructed in Visakhapatnam, India. The storage of the hydrocarbon product is based on the hydraulic containment principle using water pressure to confine the volatile products within rock caverns without any concrete or steel lining. A key feature of this project was that all underground works up to approximately 200 m depth were constructed through only two shafts of minimal diameter (4 and 6,5 m in diameter), rather like 'key-hole surgery'. This underground project had many complexities and challenges. The cavern has two limbs, each 19 × 20 m 2 in cross section and 160 m long. Many innovative construction techniques, based basically on drilling and blasting, were employed in this unique project to ensure adherence to high levels of quality, health, safety and environmental criteria stipulated by the owners and to meet the time limits for completion. This paper presents a description of the facility, the basic design aspects and the various methodologies involved in construction. The advantages of such projects, critical success factors and special issues needing attention are also described.