ASTM Environmental Site Assessment Standards

ASTM E1527-21 is the standard of practice that governs how Phase 1 Environmental Site Assessments are conducted in the United States. Published by ASTM International, it defines the scope, process, and reporting requirements that environmental professionals must follow when performing a Phase 1 ESA. If you are buying commercial property, applying for an SBA loan, or refinancing, your Phase 1 ESA must comply with this standard to be accepted by lenders and to provide legal protection under CERCLA.

What Is ASTM E1527-21?

ASTM E1527-21, formally titled "Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process," is the current version of the standard that defines how Phase 1 ESAs must be performed. It replaced the previous version, E1527-13, and was published in November 2021.

The standard specifies what an environmental professional must investigate, how the investigation must be conducted, and what the report must contain. Compliance with E1527-21 satisfies the EPA's All Appropriate Inquiries (AAI) rule under CERCLA and is required by virtually all commercial lenders.

Why the ASTM Standard Matters

The ASTM standard matters for three practical reasons:

• Legal protection. A Phase 1 ESA conducted under ASTM E1527-21 satisfies the "All Appropriate Inquiries" requirement and establishes the innocent landowner, contiguous property owner, and bona fide prospective purchaser defenses under CERCLA. Without a compliant Phase 1, buyers can be held liable for contamination they did not cause.
• Lender acceptance. Banks, SBA lenders, and other financial institutions require Phase 1 ESAs that comply with the current ASTM standard. Reports conducted under older versions or non-standard methodologies may be rejected.
• Consistent quality. The standard ensures that every Phase 1 ESA follows the same process regardless of which firm performs it. This makes reports comparable and ensures that no critical investigation steps are skipped.

What Changed from E1527-13 to E1527-21

The 2021 update made several meaningful changes to the standard:

Emerging Contaminants

E1527-21 broadened the scope to better address emerging contaminants, particularly per- and polyfluoroalkyl substances (PFAS). While PFAS are not specifically named in the standard, the updated language on "releases" and "hazardous substances" makes it clearer that the environmental professional should consider PFAS contamination where relevant.

Vapor Migration

The updated standard gives more attention to vapor intrusion and vapor migration pathways. Environmental professionals are expected to evaluate whether volatile organic compounds from contaminated soil or groundwater could migrate into buildings as indoor air contamination.

Regulatory Agency File Reviews

E1527-21 refined the requirements around reviewing regulatory agency files. The standard clarifies when it is necessary to request and review actual agency files (not just database listings) and provides more specific guidance on evaluating regulatory status of nearby contaminated sites.

Environmental Professional Definition

The updated standard refined the definition and qualifications of the "environmental professional" who must conduct or supervise the Phase 1 ESA. The requirements for education, experience, and professional licensure were clarified.

Shelf Life Clarifications

E1527-21 maintained the 180-day validity period for Phase 1 reports but clarified the procedures for updating components of aging reports.

Key Requirements of ASTM E1527-21

The standard requires the following components in every Phase 1 ESA:

• Records review. Review of historical sources including aerial photographs, fire insurance maps, city directories, building permits, and land use records to identify past uses that may have caused contamination.
• Regulatory database search. Search of federal, state, tribal, and local environmental databases for records of contamination, underground storage tanks, hazardous waste activities, and enforcement actions within specified search distances.
• Site reconnaissance. Physical inspection of the property by an environmental professional to observe current conditions and identify evidence of contamination or environmental concerns.
• Interviews. Interviews with current and past owners, operators, occupants, and local government officials to gather information about the property's history and environmental conditions.
• Report. A written report documenting all findings, the environmental professional's opinions and conclusions, and identification of any Recognized Environmental Conditions.

For a complete breakdown of what these components involve, see our Phase 1 ESA guide.

Environmental Professional Qualifications

Under ASTM E1527-21 and the EPA's AAI rule, a Phase 1 ESA must be conducted or supervised by an "environmental professional" who meets specific qualifications. These include:

• A current professional engineer (PE) or professional geologist (PG) license with environmental experience
• Or a person with a relevant bachelor's degree and 5+ years of environmental assessment experience
• Or a person with 10+ years of environmental assessment experience
• Or a licensed or certified environmental professional under a federal, state, or local program

The environmental professional must sign the Phase 1 report and include their qualifications. When selecting a firm, verify that a qualified EP will be responsible for the assessment.

All Appropriate Inquiries and EPA Regulations

The EPA's All Appropriate Inquiries (AAI) rule, codified at 40 CFR Part 312, establishes the federal requirements for environmental due diligence that must be satisfied to qualify for CERCLA liability protections. The EPA recognizes ASTM E1527-21 as a standard that satisfies the AAI requirements.

This means a Phase 1 ESA conducted under E1527-21 automatically satisfies the federal AAI rule, provided the assessment is complete and performed by a qualified environmental professional. For more on the legal framework, see our environmental due diligence guide.

ASTM E1903: The Phase 2 Standard

While E1527-21 governs Phase 1 ESAs, ASTM E1903 ("Standard Practice for Environmental Site Assessments: Phase II Environmental Site Assessment Process") governs Phase 2 assessments. E1903 provides guidance on developing sampling plans, selecting analytical methods, and evaluating results based on Phase 1 findings. For more on Phase 2 assessments, see our Phase 2 ESA guide.

How to Verify ASTM Compliance

When reviewing a Phase 1 ESA report, check for the following to confirm ASTM E1527-21 compliance:

• The report explicitly references ASTM E1527-21 (not E1527-13 or an earlier version)
• All four required components are addressed (records review, databases, site visit, interviews)
• The report identifies the environmental professional by name and includes their qualifications
• RECs, CRECs, and HRECs are clearly identified using ASTM terminology
• The report includes a limitations section and any data gaps
• Appendices include supporting documentation (database reports, maps, photographs)

Common Reasons Reports Fail Compliance

The most common reasons a Phase 1 ESA may not meet the ASTM E1527-21 standard:

• Conducted under an older standard. Reports referencing E1527-13 or earlier versions do not comply with the current standard and may not be accepted by lenders.
• Missing components. Some low-cost reports skip the site visit, omit interviews, or use abbreviated database searches. These are not ASTM-compliant.
• No qualified EP. The report was not conducted or supervised by a person meeting the environmental professional qualifications.
• "Desktop reviews" or "transaction screens." These are abbreviated assessments that do not meet the ASTM E1527-21 standard. They are useful for preliminary screening but do not provide CERCLA liability protection.
• Report is expired. A report older than 180 days has not been updated per ASTM requirements.

Get an ASTM-Compliant Phase 1 ESA

ESAquotes connects you with environmental professionals who perform Phase 1 ESAs in full compliance with ASTM E1527-21 and the EPA's All Appropriate Inquiries rule. Submit your property details to receive quotes from qualified firms.