In November 2021, the ASTM E1527-21 Standard Practice for Phase I Environmental Site Assessment (ESA) Process was published.  This will replace the 2013 historical standard and will require a review by the EPA to verify compliance with the All-Appropriate Inquiry Rule in 40 CFR Part 312.  It is anticipated this standard will pass EPA review at some point in 2022.

The new standard does not include major changes to the standard Phase I ESA process.  The update focuses on clarifying definitions and how some parts of the process should be completed to better reflect industry standard practices.  Some of the key expected updates are as stated below:

  • Use of the “Big 4”: A Phase I ESA must include review of the following resources for a subject property: historical aerial photographs, historical topographic maps, available Sanborn Fire Insurance maps, and local street/city directories.
  • Clarified definitions of Recognized Environmental Condition, Historical Recognized Environmental Condition, Controlled Recognized Environmental Condition, Property Use Limitation, and Type of Use.
  • Defined how to assess Adjoining Properties: “Use of the Adjoining Properties that are obvious shall be identified to evaluate likely presence of Recognized Environmental Conditions that could affect the subject property.”
  • New report criteria: A Phase I ESA Report must now include current photographs of the site and a site map showing borders of the property.
  • New definition: significant data gap – a data gap that affects the ability to identify a Recognized Environmental Condition on the subject property.

ATL provides this summary to bring your attention to this new standard. To discuss any implications this may have on your projects, contact our Timothy Parker at, 315-386-4578, or visit for more information.