Determine whether a standby generator's diesel fuel tank is subject to EPA underground storage tank (UST) regulation

Steps

1. Confirm the federal farm/residential exemption (RCRA) for tanks storing under 1,100 gallons of motor fuel for non-commercial use does not cover diesel used to power a generator engine — that exemption is scoped to motor fuel for vehicles, not generator fuel
2. Confirm the separate 'heating oil' exclusion only applies if the diesel is burned in equipment designed to use heating oil (e.g., a furnace/boiler) — fuel burned in a generator's engine does not qualify, per EPA's UST Technical Compendium guidance
3. Note that as of EPA's July 15, 2015 UST regulation revision (the first major update since 1988), the prior regulatory deferral for emergency generator tanks was removed, bringing emergency-generator USTs under full 40 CFR Part 280 technical/operational requirements
4. Confirm whether a specific tank is 'underground' (UST) vs 'aboveground' (AST, generally state/local-regulated rather than federal-UST-regulated) before applying Part 280, since the federal UST program only covers tanks with 10%+ of their volume below grade