It’s been 35 years since 40 CFR 280.64 was promulgated, setting Federal requirements for free product removal from underground storage tanks (USTs). Since its promulgation, much has been learned about how petroleum moves and behaves in subsurface environments. In February 2023, the EPA published UST Technical Compendium: Release Investigation, Confirmation, and Corrective Action. In the communication, the EPA reiterates the objective of 40CFR 280.64 (i.e., to remove free product to prevent migration) and recognizes that definitions of “free product” have evolved. This recognition is an acknowledgement that not all underground free products are capable of migrating; therefore, the regulation does not require the removal of all measurable free products. To read the communication, click here.