Underground Storage

Underground Storage Caverns

Since the early 2000’s, Agapito Associates,Inc. (Agapito) has contributed to the design and construction of mined underground caverns for the storage of liquefied petroleum gas (LPG), other hydrocarbons, and compressed air. Agapito provided the surface engineering for four cavern construction projects, comprising nine individual caverns for segregated product storage, with a total capacity of 14 million barrels. Our international experience is highlighted by two projects: the construction of five hydrocarbon storage caverns in Singapore and two LPG caverns in China. Domestically, AAI was the geotechnical designer for the only two mined rock caverns that have been built in the United States since the 1980’s, one near Huntington, West Virginia, and one in Robinson, Illinois. For all four projects, AAI was responsible for geotechnical and mining engineering aspects, either as the geotechnical designer, or the geotechnical consultant for the contractor or project management team. This included:

• Site characterization
• Cavern layout and opening design
• Ground support evaluation and specification
• On-site inspections to identify ground control issues, aid in constructability, and ensure that the as-built excavations conformed to the geotechnical design intent

Click the links below for details of each project:

• Butane and propane caverns, Guangdong Province, China
• LPG cavern, Neal, West Virginia
• Liquid hydrocarbon caverns, Singapore
• Butane storage cavern, Robinson, Illinois

Geotechncial Analysis of Existing Mined Storage Caverns

In addition to the newly constructed storage caverns discussed above, Agapito completed geotechnical evaluations for multiple existing mined storage caverns near their original designed life to assess the associated risk of continued operation. From the 1950’s through the 1980’s, several dozen mined storage caverns were constructed in the United States. In recent years, there has been interest in assessing their current stability, especially with regard to rock fatigue associated with age and pressure cycling (pressure decrease as product is withdrawn, and pressure increase as product is injected). Because the facilities are normally still in use, visual inspection is not possible. Agapito has applied numerical modeling techniques to back-analyze the facilities, and applied rock fatigue research to predict the likely current and future stability for several storage caverns, including:

• A storage cavern excavated in chalk, Demopolis, Alabama
• Seven caverns in Middletown, Ohio; Seymour, Indiana; Iowa City, Iowa; and Princeton, Indiana
• Caverns in Griffith, Indiana; Huntington, Indiana; and Tuscola, Illinois

Agapito staff possess additional capabilities in support of underground storage cavern projects, including:

• Rock mechanics including laboratory testing
• Underground ventilation engineering
• Excavation planning, including geologic modeling and operations scheduling, staffing requirements
• Detailed excavation design, including geotechnical analysis, infrastructure requirements, and costing
• Ground control and subsidence engineering
• Blasting engineering
• Pre-excavation exploration programs
• Geotechnical instrumentation installation