Phase 1 environmental site assessment checklist: what a Phase I includes

Short answer: A Phase I Environmental Site Assessment (ESA) under ASTM E1527-21 covers the 10 elements of EPA’s All Appropriate Inquiries rule (40 CFR 312.21 and 312.23-312.31). An Environmental Professional reviews government records and historical sources, inspects the property, interviews owners and occupants, and signs an opinion. Four of the 10, starting with the environmental lien search, are the buyer’s own inquiries. It excludes sampling, asbestos, lead paint, radon and mold.

Use this Phase 1 environmental site assessment checklist to compare quotes, prepare your own part of the work, or review a report a seller or lender hands you. It reflects the rules in force on October 19, 2026.

Three terms run through the checklist. All Appropriate Inquiries (AAI) is the pre-purchase investigation defined by EPA’s rule at 40 CFR Part 312. An Environmental Professional (EP) is the person, qualified under 40 CFR 312.10, who runs that inquiry and signs the report; our About page sets out who can perform a Phase I and who signs ours. A recognized environmental condition (REC) is what the inquiry looks for: hazardous substances or petroleum products present at the property because of a release, likely present because of a release or likely release, or present under conditions that pose a material threat of a future release (ASTM E1527-21, section 1.1.1).

The Phase 1 environmental site assessment checklist, part by part

The table follows the 10 criteria that CERCLA, the federal Superfund law, sets for AAI (42 U.S.C. 9601(35)(B)(iii)), as EPA wrote them into 40 CFR 312.21 and 312.23-312.31. In the Rule column, the first number is the 40 CFR section and the second is the E1527-21 section, taken from EPA’s comparison of the AAI rule and E1527-21. “You” means the user: the buyer, borrower or other party seeking CERCLA protection.

Five components are time-sensitive: the interviews, lien search, records review, site visit and EP declaration must be conducted or updated within 180 days before acquisition, and the whole inquiry within one year (40 CFR 312.20). Both clocks run from the component dates, not the report date, and the one-year clock runs from the oldest work in the inquiry (E1527-21, section 4.6.3). The Phase I 180-day rule guide works through the dates.

SBA loans use a different clock. The U.S. Small Business Administration (SBA) will accept for review an otherwise AAI-compliant Phase I dated within one year of the date the SBA loan number is issued, notwithstanding EPA’s 180-day rule. SBA adds that parties may still want to meet EPA’s timeframes so they do not jeopardize their legal and regulatory protections (SOP 50 10 8.1, Appendix 4, definition of Phase I Environmental Site Assessment).

Your part: the user’s responsibilities

The AAI rule assigns 4 inquiries to you (40 CFR 312.22). E1527-21 says you should give the results to the EP, who should otherwise weigh what their absence means (EPA comparison, p. 9). The inquiry is not complete without your specialized knowledge (40 CFR 312.28(b)).

• Lien and AUL search. The environmental cleanup lien search is mandatory under 40 CFR 312.25. E1527-21 adds activity and use limitations (AULs) and makes both your job unless you engage the EP for them: a review of land title and judicial records such as deeds, easements, liens and AULs (Mitchell Williams slides). You can rely on the title commitment or preliminary title report for your purchase, reviewed by you or a title professional you engage, or on a title search report that covers land title records back to 1980 (Holland & Knight). The lien search date counts toward the 180 days.
• Specialized knowledge. Anything you know that bears on contamination, such as a past tank removal or a tenant’s chemical use. E1527-21 asks you to tell the EP before the site visit (EPA comparison, p. 11).
• Purchase price versus value. Consider whether the price reflects the property’s value if it were not contaminated and, if not, whether contamination explains the gap (40 CFR 312.29). You need not disclose the price itself.
• Commonly known information. Local knowledge from neighbors, officials, newspapers, websites and libraries (40 CFR 312.30). You and the EP share this one.
• User Questionnaire. E1527-21 Appendix X3 is an optional form that collects these items. The form is optional; the information is not. For SBA loans, the Appendix 5 reliance letter certifies that the EP addressed the 312.22 inquiries (SOP 50 10 8.1, Appendix 5).

Also send:

• Prior environmental reports and permits. A prior report can guide the EP but cannot stand in for current site conditions (EPA comparison, p. 11).
• Access and interview contacts. A seller’s refusal to give access does not excuse the site visit (40 CFR 312.27(c)).
• Your intended future use of the property, one of the factors that shape the level of inquiry (E1527-21, section 4.5.3).
• Any added scope from the list further down, agreed before work starts.

If you rely on a Phase I someone else ordered, such as the seller’s, you must still review it and make your own specialized knowledge, purchase price and commonly known information inquiries (40 CFR 312.20(d)(2)), and E1527-21 expects you to meet all of the user’s responsibilities in its section 6 (section 4.6.4).

How far the search reaches, in distance and in time

For the property itself, the records review should include reported releases, tank, landfill and hazardous waste records, public health and emergency response records, and registries of engineering and institutional controls (40 CFR 312.26). For nearby sites, the rule sets these distances from the property boundary:

The EP may change a distance for reasons such as geology, groundwater flow or nearby uses, but must document why (40 CFR 312.26(d)). E1527-21 sets its own minimum search distances, which the EP may also adjust. EPA’s comparison notes one difference from the rule: E1527-21 searches engineering and institutional control registries for the property only (p. 11).

In time, the federal rule reaches back as far as the property contained structures or was first used for residential, agricultural, commercial, industrial or governmental purposes (40 CFR 312.24(b)). E1527-21 is more stringent. The EP identifies every obvious use back to first developed use or 1940, whichever is earlier, and “developed use” includes farming and the placement of fill even where there are no buildings (EPA comparison, p. 10).

E1527-21 names 8 standard historical sources (NEWMOA presentation). Four must be reviewed when they are reasonably ascertainable, likely to be useful and applicable to the property: aerial photographs, fire insurance maps, local street directories and topographic maps. The other 4 are building department records, interviews, property tax files and zoning records. When the first 4 were researched for the property, cover adjoining properties and are likely to be useful, they should be reviewed for those properties too. For retail, industrial or manufacturing property, the sources should also be reviewed when they are likely to identify a more specific use (EPA comparison, p. 2), since a building listed only as “retail” may once have held a dry cleaner (NEWMOA presentation).

How to read the findings: REC, CREC, HREC, de minimis and data gaps

A REC and a CREC go in the report’s Conclusions; an HREC and a de minimis condition are not RECs. The definitions below follow ASTM E1527-21 (section 1.1.1), EPA’s comparison (pp. 2-3, 5 and 7-8) and the NEWMOA presentation. The guide to RECs covers what usually follows each one.

“Likely” means neither certain nor proved, but expected by a reasonable observer from the EP’s logic, experience or the available evidence. A CREC label does not mean the EP confirmed that the controls work (NEWMOA presentation). A data gap becomes significant only when it raises a reasonable concern about the EP’s opinion, as with a building that could not be entered during the site visit and that, in the EP’s experience, houses activities that can lead to a REC (National Law Review).

E1527-21 calls for the EP’s opinion on whether more investigation may be appropriate, not a specific recommended course of action (EPA comparison, p. 3). SBA loans go further: the EP must conclude either that the risk is so minimal that no further investigation is warranted or that it is sufficient to warrant more (or make a similar statement), and should describe any recommendation in detail (SOP 50 10 8.1, Appendix 4, “Phase I Environmental Site Assessment”). No Phase I removes all uncertainty, and ASTM says AAI is not an exhaustive assessment (E1527-21, sections 4.5.1 and 4.5.2).

A 17-point checklist for reviewing a Phase I report

Run these 17 checks on any report, including one prepared for someone else. A report missing an item the rule or E1527-21 requires is incomplete, whatever its cover says. Row 17 applies only to SBA loans.

Print it and mark each line. It does not replace the EP’s judgment, but it shows quickly whether the required parts are there.

What is outside the Phase 1 ESA scope of work

E1527-21 covers CERCLA hazardous substances and petroleum products. Everything else is a non-scope consideration, and any you want investigated should be agreed with the EP as an added service before work starts (section 1.4). The non-scope list includes asbestos, lead-based paint, lead in drinking water, radon, mold, wetlands, cultural and historic resources, endangered species, industrial hygiene, regulatory compliance and substances that are neither CERCLA hazardous substances nor petroleum products, such as emerging contaminants not yet designated (NEWMOA presentation, citing section 13.1.5).

A standard Phase I also involves no testing, and the AAI rule does not require sampling (EPA Common Elements guidance, p. 6, note 22). Confirming or ruling out a REC takes a Phase II ESA.

For SBA loans on child-occupied facilities built before 1978, SBA requires a lead risk assessment and lead-in-drinking-water testing within one year of the date the SBA loan number is issued (SOP 50 10 8.1, Section A, Chapter 5, Paragraph E.6.a).

Vapor and PFAS: what a standard Phase I covers

Vapor migration versus an ASTM E2600 vapor encroachment screen

A standard Phase I considers vapor migration. When EPA recognized E1527-13 in 2013, it said that standard’s revisions clarify that AAI and Phase I assessments must include an assessment of the real or potential occurrence of vapor migration and vapor releases on, at, in or to the property. EPA added that, in its view, vapor migration has always been a relevant potential source of release that, depending on site-specific conditions, may warrant identification (78 FR 79321-79322). A current E1527-21 Phase I therefore considers whether vapor from a release on or near the property may be migrating in the subsurface, using the same records, history, interviews and observations as the rest of the report.

ASTM E2600-22 is a separate guide for vapor encroachment screening: it looks for chemicals of concern present or likely present as vapor beneath the property because of contaminated soil or groundwater on or near it. It can be used with a Phase I or on its own, it does not define or expand the Phase I scope, and AAI does not require it (ASTM E2600-22, sections 1.1 and 4.2.2). A standard Phase I does not sample soil gas or test indoor air; that belongs to a Phase II or a vapor intrusion investigation.

PFOA and PFOS are now CERCLA hazardous substances

E1527-21 treats emerging contaminants, including PFAS, as non-scope until they are defined as CERCLA hazardous substances, at which point they must be evaluated within scope (EPA comparison, p. 3). EPA designated PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid), with their salts and structural isomers, in a rule effective July 8, 2024 (89 FR 39124), and both are listed in 40 CFR 302.4.

The designation remains in force. On September 17, 2025, EPA said it was retaining it (EPA news release), and on August 18, 2026, the D.C. Circuit denied the petitions challenging the rule (Chamber of Commerce v. EPA, No. 24-1193).

A current Phase I therefore considers PFOA and PFOS like any other hazardous substance, through records, historical use, interviews and observation, without testing for them. A September 2024 law firm alert reached the same conclusion on scope, and recommended that a Phase I report the results of PFAS database screening, such as EPA’s PFAS Analytic Tools, for the property and nearby sites (Kazmarek Mowrey Cloud Laseter). Other PFAS remain non-scope, so if your state regulates them or your lender asks, add them before work starts.

The rules behind a Phase I

CERCLA can hold the current owner of contaminated property strictly liable for cleanup, meaning liability can rest on ownership alone (42 U.S.C. 9607(a); EPA fact sheet, page 1). It offers defenses to buyers who carried out “all appropriate inquiries” before acquiring the property, and it lists the 10 criteria EPA’s AAI rule must include (42 U.S.C. 9601(35)(B)(iii)).

EPA set those criteria out in 40 CFR Part 312, effective in 2006. The rule lets you comply through ASTM E1527-21 for commercial property or ASTM E2247-23 for forestland or rural property (40 CFR 312.11). Using an ASTM standard is optional: EPA has said that use of E1527-21 is not required to comply with the AAI rule, and a party may follow 40 CFR Part 312 directly (87 FR 76580). SBA, for one, defines a Phase I as one conducted to ASTM E1527-21 (SOP 50 10 8.1, Appendix 4). EPA recognized the older E1527-13 only until February 13, 2024 (40 CFR 312.11(c)).

A Phase I satisfies one requirement of CERCLA’s landowner liability protections; it does not preserve them by itself, and E1527-21 does not address whether the other requirements are met (ASTM E1527-21, sections 1.1 and 1.1.3). The bona fide prospective purchaser (BFPP) defense that most buyers rely on also requires your own inquiries under 40 CFR 312.22 and continuing obligations after closing, such as reasonable steps and compliance with land use restrictions (42 U.S.C. 9601(40)(B)). Whether you qualify is a question for your attorney.

What changed with ASTM E1527-21, and how to spot an older report

ASTM published E1527-21 in November 2021, and EPA recognized it as compliant with the AAI rule effective February 13, 2023, describing the differences from the rule as minor (EPA comparison, pp. 1-3; 87 FR 76578). The REC, CREC and HREC definitions were reworded without changing their concepts, and the standard added defined terms such as “likely” and “significant data gap” (EPA comparison, p. 2).

Several of those changes show in the report, so the checklist above also flags a report written to the older standard or not brought up to date:

• Row 3: the conformance statement names E1527-13, or none names E1527-21 (EPA comparison, p. 9).
• Row 9: the site visit section lists what was found, not what was and was not present (p. 2).
• Rows 10 and 11: no site plan, or no photographs of conditions indicative of RECs and de minimis conditions (pp. 2 and 8).
• Row 14: Conclusions that list RECs but not significant data gaps (pp. 2-3).
• Row 16: PFOA and PFOS listed as non-scope, which has been out of date since July 8, 2024.

What our $1,495 Phase I includes

Our Phase I is written to ASTM E1527-21 and 40 CFR Part 312 and signed by an Environmental Professional who meets 40 CFR 312.10. The flat price covers:

• Federal, state, tribal and local regulatory records for the property and nearby sites at the 40 CFR 312.26 and ASTM search distances
• Historical sources back to first developed use or 1940, whichever is earlier: aerial photographs, fire insurance maps, city directories and topographic maps
• A site reconnaissance with photographs by a qualified local professional under the Environmental Professional’s supervision, including views of adjoining properties
• Interviews with the owner, occupants and local agencies, and review of your User Questionnaire
• Findings and an opinion on RECs, CRECs, HRECs, de minimis conditions, significant data gaps and whether further investigation is warranted
• Consideration of potential vapor migration as part of the E1527-21 assessment
• The report signed by the EP with the 40 CFR 312.21(d) declarations and the dates of the interviews, records review, site visit and declaration
• Reliance for your lender, including the SBA SOP 50 10 8.1 Appendix 5 reliance letter; each additional reliance party is $99, with the letter issued within 1 business day of a complete request

Not included: sampling of soil, groundwater, soil vapor or indoor air (Phase II); asbestos, lead-based paint, lead in drinking water or radon surveys unless ordered; mold surveys; wetlands, endangered species, cultural resources or National Environmental Policy Act (NEPA) reviews; ASTM E2600 vapor encroachment screening; regulatory compliance audits; and substances that are neither CERCLA hazardous substances nor petroleum products, such as PFAS other than PFOA and PFOS. The environmental lien and AUL search is your responsibility under E1527-21 and is not in the flat price, so order it through your title company and send us the results.

The flat price applies to one parcel, up to 5 acres, up to 3 buildings and 50,000 square feet total, and a current use that is not heavy industrial or manufacturing; multiple parcels, including contiguous parcels under one owner, get scope review and a fixed quote before authorization. Delivery is 5 business days from authorization and confirmed site access, or 3 business days with a $400 rush, and we confirm scope, price and delivery date within 1 business hour. If your lender requires a radius report from a named commercial data vendor, we attach one for $200.

In October 2026, most Phase I prices and ranges other firms published on their websites ran about $1,800 to $5,000; the Phase I cost guide compares them. Our $1,495 is lower because we built proprietary internal technology that collects and organizes the regulatory and historical records the day an order is authorized, so the Environmental Professional reviews an organized record instead of assembling one.

If we miss the delivery date we commit to for a reason within our control, we take $250 off. If noncompliance with ASTM E1527-21 or SOP 50 10 8.1 causes a lender or SBA rejection, we correct the report at no charge, or refund its fee if we cannot, subject to the exclusions in our engagement terms. The Phase I ESA service page has the full scope and how to order.

Sources

1. 40 CFR Part 312, Innocent Landowners, Standards for Conducting All Appropriate Inquiries, Electronic Code of Federal Regulations (current to October 16, 2026), accessed October 2026
2. ASTM E1527-21, Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process (scope and significance), ASTM International, accessed October 2026
3. 42 U.S.C. 9601, Definitions (CERCLA section 101), U.S. Code 2024 edition, U.S. Government Publishing Office, accessed October 2026
4. Comparison of All Appropriate Inquiries Regulation, the ASTM E1527-13 Phase I Environmental Site Assessment Process, and ASTM E1527-21 Phase I Environmental Site Assessment Process, U.S. EPA docket document for EPA-HQ-OLEM-2021-0946 (copy hosted by the Wisconsin Department of Natural Resources), accessed October 2026
5. SOP 50 10 8.1, Lender and Development Company Loan Programs, with Technical Policy Updates, effective October 1, 2026 (Word document), U.S. Small Business Administration, accessed October 2026
6. Recent Updates to ASTM E1527-21 (presentation), Thomas Huetter, P.G., hosted by Mitchell Williams, accessed October 2026
7. EPA Recognizes ASTM E1527-21 as Satisfying All Appropriate Inquiries Rule, Amy L. Edwards and Dianne R. Phillips, Holland & Knight, December 20, 2022, accessed October 2026
8. ASTM Update: E-1527-21 (presentation, NEWMOA webinar, May 23, 2023), Elizabeth Krol, Ramboll, for the Northeast Waste Management Officials’ Association, accessed October 2026
9. The New ASTM E1527-21 Standard Practice for Phase I Environmental Site Assessments (ESA), David P. Ruetz, National Law Review, November 18, 2021, accessed October 2026
10. Enforcement Discretion Guidance Regarding Statutory Criteria for Those Who May Qualify as CERCLA Bona Fide Prospective Purchasers, Contiguous Property Owners, or Innocent Landowners (“Common Elements”), U.S. EPA, July 29, 2019, accessed October 2026
11. Amendment to Standards and Practices for All Appropriate Inquiries Under CERCLA, 78 FR 79319 (December 30, 2013), Federal Register, accessed October 2026
12. ASTM E2600-22, Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions (scope and significance), ASTM International, accessed October 2026
13. Designation of PFOA and PFOS as CERCLA Hazardous Substances, final rule, 89 FR 39124 (May 8, 2024), Federal Register, accessed October 2026
14. 40 CFR 302.4, Hazardous substances and reportable quantities, Electronic Code of Federal Regulations, accessed October 2026
15. Trump EPA Announces Next Steps on Regulatory PFOA and PFOS Cleanup Efforts, Provides Update on Liability and Passive Receiver Issues, U.S. EPA news release, September 17, 2025, accessed October 2026
16. Chamber of Commerce of the United States v. EPA, No. 24-1193 (D.C. Cir. August 18, 2026), U.S. Court of Appeals for the D.C. Circuit, accessed October 2026
17. Client Alert: Requirements for PFAS Analysis in Phase I Environmental Site Assessments, Chris J. Williams and Leland P. Frost, Kazmarek Mowrey Cloud Laseter LLP, September 27, 2024, accessed October 2026
18. 42 U.S.C. 9607, Liability (CERCLA section 107), U.S. Code 2024 edition, U.S. Government Publishing Office, accessed October 2026
19. EPA Brownfields Grants, CERCLA Liability, and All Appropriate Inquiries (fact sheet EPA 560-F-23-003), U.S. EPA, July 2024, accessed October 2026
20. Standards and Practices for All Appropriate Inquiries, final rule, 87 FR 76578 (December 15, 2022), Federal Register, accessed October 2026