CLIENT ALERT: EPA Approves Use of Revised E1527-21 Standard for Phase I Environmental Site Assessments

The new ASTM standard (ASTM E1527-21) for Phase I Environmental Site Assessments (ESAs) was published in November 2021. On December 15, 2022, USEPA published a direct final rule approving the new standard for conducting the all appropriate inquiry (AAI) component for potential liability protections under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). With this final rule, the ASTM E1527-21 Standard Practice on Phase I ESAs has been recognized by the USEPA as satisfying the AAI rule (40 CFR Part 312).


Based on USEPA’s proposed and direct final rules published March 14, 2022, the new ASTM Standard was to be incorporated into the AAI Rule May 13, 2022, while retaining the recognition of the old standard (ASTM E1527-13). USEPA asked for public comment through April 13, 2022. Many commenters were particularly concerned on how the option of using the old or new standard at the discretion of the parties would create confusion in assessment and transactions. Due to the comments received, USEPA withdrew the May 2 direct final rule.

Impact on Phase I ESAs

The final rule will take effect 60 days from the date of publication, on February 13, 2023. The rule will no longer recognize the use of the former ASTM E1527-13 standard to satisfy the AAI requirement; however, USEPA is providing a sunset period, which will allow use of the former standard for a period of one year following publication. At that time, only the new ASTM E1527-21 standard will be recognized.

What’s Next?

EHS Support is prepared to incorporate the changes to the new ASTM standard. If you have any questions on how the new ASTM Phase I standard may impact your environmental due diligence, please contact Beth Hesse ( or Kai Kasprick ( at EHS Support for additional details.



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