An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Is underground storage included in the definition of a process?

Would underground storage of a regulated substance listed at 40 CFR §68.130 subject a stationary source owner or operator to the risk management program regulations?

If more than a threshold quantity of a regulated substance is present in a process at a stationary source, the owner or operator of that source must comply with the risk management program regulations at 40 CFR Part 68. The definition of "process" includes storage of a regulated substance, and there is no general exemption for underground storage.