Quintessa was sub-contracted by BGS to support this project by developing leakage scenarios and carrying out simple scoping calculations to evaluate the likely significance of leakage. The BGS component of the work is reported in HSE RR605, which provides context, background and data for the work reported by Quintessa in HSE RR606.
A database of Features, Events and Processes (FEPs) was used to audit the issues identified by BGS as potentially influencing whether or not gas leakage will occur. Three basic scenarios were identified as relevant to existing or potential onshore UGS facilities in the UK. For each scenario, scoping calculations were carried out to evaluate limiting gas fluxes and surface emission areas.