Risk assessment of a propane storage sphere: Maintain or decommission?

The authors were asked to assist a utility with a risk management decision. Specifically, the utility was considering whether they should maintain or decommission an 800,000 gallon propane storage sphere. The 30‐year old sphere was the fuel storage vessel for a propane standby system. One of their major concerns was the shrinking buffer zone around their facility. Although the facility was originally located in a remote rural area, residential development had begun to encroach upon the facility's buffer zone.