On February 13, 2024, the ASTM 1527-13 standard for Phase I environmental site assessments will phase out and no longer satisfy All Appropriate Inquiry (AAI), as defined by the EPA. Instead, consultants should perform Phase Is after this date pursuant to the newer ASTM 1527-21 standard to meet the requirements of AAI.

In addition to identifying environmental issues at a subject property, Phase Is are often used by buyers in real estate transactions to satisfy their compliance with AAI and avail themselves of CERCLA defenses to liability. Additionally, lenders often require Phase Is performed in accordance with the correct standards, and other state programs that require Phase Is may update guidance or revise regulations to adopt the new ASTM 1527-21 standard. 

From a practical standpoint, there should not be a significant learning curve or delay after the old standard sunsets.  Many consultants began performing Phase Is pursuant to ASTM 1527-21 in 2023.  However, it is an easily overlooked component of a Phase I that buyers and other parties to real estate transactions should closely scrutinize in the months following the phase out date.