Phase 1 Environmental Site Assessment: Cost and Timing

A Phase 1 environmental site assessment (Phase I ESA) is a review of a property's records, history and current condition for signs of contamination by hazardous substances or petroleum. An environmental professional does it before a purchase, usually to the ASTM E1527-21 standard. It involves no sampling. Buyers order one for protection from cleanup liability and because lenders ask.

Pillar, a land research software company, wrote this guide. The rules, statutes and published figures below link to their sources, and we checked them on November 13, 2026. This is general information. Liability depends on the facts and on state law as well as federal, so confirm your situation with an environmental professional and an environmental attorney in your state.

What is a Phase 1 environmental site assessment?

Regulations and reports write it with a Roman numeral, Phase I. The federal rule behind it is EPA's All Appropriate Inquiries rule, 40 CFR part 312. EPA describes all appropriate inquiries as "the process of evaluating a property's environmental conditions and assessing potential liability for any contamination." The rule lists what the inquiry must contain, and says a buyer may comply by following ASTM International's standard E1527-21.

EPA recognized E1527-21 in a final rule published December 15, 2022, effective February 13, 2023. The same rule ended recognition of the older E1527-13 standard on February 13, 2024, so a current report should cite E1527-21. EPA wrote that the rule "does not require any entity to use this standard."

Home buyers are treated differently. The statute says that for property bought for residential use by a nongovernmental or noncommercial buyer, "a facility inspection and title search that reveal no basis for further investigation" satisfy the inquiry requirement.

Why do buyers order a Phase 1 ESA?

Cleanup liability follows ownership. Under the federal Superfund law, CERCLA, the current "owner and operator" of a facility is one of four classes of liable parties (42 U.S.C. 9607(a)). Ohio EPA's fact sheet on property transfers says "property owners can be held liable for the cleanup of environmental contamination on their property even if they did not cause the contamination."

CERCLA has three landowner liability protections. All three require the buyer to have made all appropriate inquiries by the time of purchase. All three also require the owner to take reasonable steps to stop any continuing release, prevent any threatened future release and limit exposure. The owner must cooperate with and give access to those doing an authorized cleanup, and comply with land use restrictions without impeding institutional controls. The bona fide prospective purchaser and contiguous property owner provisions extend the cooperation duty to natural resource restoration. The owner has to prove the conditions by a preponderance of the evidence. The rest differs:

• Bona fide prospective purchaser (42 U.S.C. 9601(40) and 9607(r)). For a buyer who acquires the property after January 11, 2002. EPA says such a buyer may acquire it "knowing, or having reason to know, of contamination." All disposal of hazardous substances must have happened before the purchase. The buyer must give all legally required notices, comply with information requests and subpoenas, and not be potentially liable, or affiliated with a potentially liable party, through the relationships the statute lists. The buyer must also not impede a response action or natural resource restoration.
• Innocent landowner (42 U.S.C. 9601(35) and 9607(b)(3)). For a buyer who acquired the property after the disposal and "did not know and had no reason to know" of it. The release and the resulting damage must have been caused solely by a third party who is not the buyer's employee or agent and has no disqualifying contractual relationship with the buyer. The buyer must show due care with the hazardous substance and precautions against the foreseeable acts of third parties, and must not have caused or contributed to the release. An owner who gets actual knowledge of a release or threatened release while owning the property, and then transfers ownership without disclosing it, loses the defense.
• Contiguous property owner (42 U.S.C. 9607(q)). For an owner of land that is contiguous to, or otherwise similarly situated with respect to, another person's property, and that is or may be contaminated by a release or threatened release from it. The owner must not have caused, contributed to or consented to the release. The notice and information request conditions apply here too, and the section has its own affiliation limits. At purchase, the owner must not have known, or had reason to know, that the property was or could be contaminated from property the owner does not own or operate. An owner who did know may still qualify as a bona fide prospective purchaser.

Lenders ask for it. Lenders that hold a mortgage mainly as security, and stay out of managing the facility, have their own exemption from CERCLA owner and operator liability, and EPA says it "is not conditioned by a bank or lender undertaking AAI."

One published lender rule is the Small Business Administration's SOP 50 10 8.1, effective October 1, 2026, for 7(a) and 504 loans. It "requires an Environmental Investigation of all commercial Property" offered as security. Where the property's current or known prior use matches a listed environmentally sensitive industry, the investigation "must begin with a Phase I, regardless of the amount of the loan." For other properties, a loan of up to $250,000 may begin with an environmental questionnaire, and a larger loan must begin with at least the questionnaire and a records search with risk assessment. Units in multi-unit buildings, gas stations and dry cleaners have their own rules.

Is a Phase 1 ESA required by law? Ohio EPA says its regulations "do not require that an environmental site assessment be conducted for a property transfer," and that "many banks will require" one. Other states' rules can differ.

What does a Phase 1 ESA include?

Part 312 sets out the parts. EPA's comparison of the rule with E1527-21 notes where the ASTM standard asks for more.

• Government records. Federal, state, tribal and local records for the property and its surroundings. Section 312.26 sets search distances from the property boundary: one mile for National Priorities List (Superfund) sites, one-half mile for state cleanup and brownfields sites, leaking underground storage tanks and landfills, and adjoining properties for registered storage tanks and hazardous waste generators. The environmental professional may change a distance and must document why.
• Historical sources. Section 312.24 names "aerial photographs, fire insurance maps, building department records, chain of title documents, and land use records." EPA's comparison says E1527-21 adds local street directories and historical topographic maps. Its research goes back to the first developed use or to 1940, whichever is earlier, and counts farming and the placement of fill dirt as developed use.
• Site visit. A visual inspection of the property, and of adjoining properties from the property line or a public right-of-way (section 312.27). A voluntary seller's refusal to give access does not excuse the on-site inspection.
• Interviews. The current owner and occupant and, as needed, past owners, operators, occupants, facility managers or employees (section 312.23). EPA's comparison says E1527-21 also calls for interviews with local government officials.
• The buyer's own duties. The buyer must search for recorded environmental cleanup liens, take account of any specialized knowledge of the property and the area, and consider whether the price reasonably reflects fair market value if the property were not contaminated. A buyer who concludes it does not must consider whether contamination explains the gap. The buyer must also consider commonly known or reasonably ascertainable information about the property, if the professional has not already gathered it (section 312.22). Under E1527-21 the buyer also reviews land title records for activity and use limitations.
• The report. A written report with the professional's opinion on whether the inquiry found "conditions indicative of releases or threatened releases," the data gaps, the professional's qualifications and signed declarations (section 312.21).

Who can do a Phase 1 ESA? An "environmental professional" under section 312.10. The person must have the specific education, training and experience needed to form professional opinions about releases or threatened releases, plus one of four qualifications: a current professional engineer's or professional geologist's license or registration from a state, tribe or U.S. territory and the equivalent of three years of full-time relevant experience; a federal, state, tribal or territorial license or certification to perform environmental inquiries and the equivalent of three years of full-time relevant experience; a bachelor's degree or higher in engineering or science from an accredited institution and the equivalent of five years of full-time relevant experience; or the equivalent of ten years of full-time relevant experience. The rule does not override state licensing laws. Others may assist under supervision.

What is a recognized environmental condition (REC)?

This is the finding a Phase I exists to make. ASTM's published scope gives three forms. One is "the presence of hazardous substances or petroleum products in, on, or at the subject property due to a release to the environment." The second is their "likely presence" due to "a release or likely release." The third is their presence "under conditions that pose a material threat of a future release to the environment."

ASTM sells the full standard. The related definitions below are quoted from Akerman's July 2022 summary of it.

• Controlled REC (CREC). A REC "addressed to the satisfaction of the applicable regulatory authority or authorities with hazardous substances or petroleum products allowed to remain in place subject to implementation of required controls," such as activity and use limitations.
• Historical REC (HREC). A past release addressed to the regulator's satisfaction and "meeting unrestricted use criteria," with no controls on the property. "A historical recognized environmental condition is not a recognized environmental condition."
• De minimis condition. "A condition related to a release that generally does not present a threat to human health or the environment" and would not generally draw enforcement. ASTM's scope says it is not a REC.
• Business environmental risk. ASTM's public text says extra services a buyer adds "may include business environmental risk (BER) issues not included within the scope of this practice."

A July 2025 Phase I prepared for the City of Mansfield, Ohio, for a street corridor project shows what findings look like. Its summary lists a former dry cleaner at one address from 1949 to 1985, filling stations on two corners in the 1940s and the 1970s, and a site on the state's leaking tank list "listed as having an unresolved issue."

How long is a Phase 1 ESA good for?

Section 312.20 sets two limits. Both count back from the date of acquisition, defined as "the date on which a person acquires title to the property."

• One year. The inquiry "must be conducted within one year prior to the date of acquisition."
• 180 days. Five components "must be conducted or updated within 180 days of and prior to the date of acquisition": the interviews, the search for environmental cleanup liens, the government records review, the visual inspections, and the environmental professional's declaration.

The date on the report cover is the wrong place to start counting. ASTM's published text for E1527-21 says the dates of the interviews, records review, visual inspections and declaration "shall be identified in the report." It adds that the report date "generally does not represent the date the individual components of all appropriate inquiries were completed and should not be used when evaluating compliance with the 180-day or 1-year all appropriate inquiries requirements." Holland & Knight's summary says the clock "begins to run from the first of these activities."

A worked example

These dates are illustrative. A builder signs a contract for a 40-acre tract on January 11, 2027, with closing tied to a rezoning. The Phase I report states these dates:

• Government records search: January 19, 2027. Its 180th day is July 18.
• Environmental lien search: January 21. Its 180th day is July 20.
• Site visit and owner interview: January 26. Their 180th day is July 25.
• Report signed with the declaration: February 9. Its 180th day is August 8.
• One year from the earliest work on January 19: January 19, 2028. The rule does not name a start date for the year, so this example counts from the earliest work to be safe, and assumes the historical research was also done on January 19.

Three ways the closing can go:

1. Closing on June 30, 2027. That is 162 days after the records search. All five components are inside 180 days.
2. The rezoning hearing is continued and closing moves to August 2, 2027. By its cover date the report is 174 days old and looks current. The records search is 195 days old, the lien search 193, and the site visit and interview 188. Those four must be updated, and the professional signs a new declaration. The historical research is inside one year, but the rule still requires older information to be updated for relevant changes in the property's condition, so the consultant checks whether anything has changed.
3. Closing slips past January 19, 2028. On this example's conservative count, the oldest work is more than a year old, and the consultant has to redo or update it. ASTM's text lets the consultant use the earlier report as an information source, but not "without current investigation."

The rule says "within 180 days" and gives no counting convention beyond that, so do not schedule a closing for the last day.

A lender may count differently. The SBA accepts a Phase I "dated within one year of the date of issuance of the SBA loan number," and warns that parties "may still wish to strictly comply with EPA's regulatory timeframes."

How much does a Phase 1 ESA cost, and how long does it take?

There is no official price. These published figures disagree at both ends:

• Ohio EPA, February 2023: "A typical ASTM Phase I will usually cost between $2,000 and $6,000."
• National Park Service, a brownfields article last updated January 19, 2024: a qualified environmental professional "will charge $3,000-$4,000 for a Phase I ESA."
• Iowa Department of Natural Resources, a brownfield program sheet in a file dated October 2025: "Average cost: $2,000 to $3,000."
• Oklahoma Corporation Commission, an undated brownfields fact sheet in a file dated May 2025: "between $1,500 and $12,000 depending on the size of the property and whether they are also ordering other subsurface surveys."
• iSi Environmental, a consulting firm, on October 23, 2026: its own Phase I reports "run $3,500 to $8,000 per site" for a typical commercial site.

A Phase II costs more. The National Park Service article says it "can range from the tens of thousands to over $100,000."

Oklahoma's brownfields program says it "may take 2-3 months from your enrollment in the Brownfield Program to have a completed Phase I Report," which is specific to that program. For private work, iSi puts industry-typical turnaround at "three to four weeks." NOVA Engineering said on January 12, 2026 that a Phase I on a straightforward property "typically takes two to four weeks from initiation to final report."

Phase 1 vs Phase 2 environmental site assessment

A Phase I reviews records and history, inspects the site and interviews people. A Phase II samples. Ohio EPA says it "includes sampling areas of suspected contamination to confirm the presence, type and levels of contaminants." ASTM's Phase II standard is E1903-19. A buyer usually orders one when the Phase I finds a REC and the buyer still wants the property.

Two other ASTM standards get confused with a Phase I:

• Transaction screen (E1528-22). A lighter review built on questionnaires. ASTM's published text says it is for cases where "the parties do not seek CERCLA LLPs," meaning the landowner liability protections, and that it "is not intended to permit a user to satisfy" them.
• Forestland and rural property (E2247-23). A second Phase I standard that supports the same protections. EPA recognized it in a final rule published June 24, 2024, effective August 23, 2024, and recognition of the older E2247-16 ended on June 24, 2025. ASTM's published scope calls it "a more practical approach to assess rural property and forestland properties that are generally uniform in use."

A free desktop pre-check before you order a Phase 1

This does not replace a Phase I and gives no liability protection. It tells you what to ask the consultant and whether a Phase II is likely.

1. Federal cleanup sites. EPA's Cleanups in My Community maps Superfund sites, RCRA corrective actions and brownfields properties. Look a mile around the parcel, the rule's longest search distance.
2. Regulated facilities. Envirofacts, which EPA calls "a single point of access to select U.S. EPA environmental data," lists facilities by ZIP code, city or county, including hazardous waste handlers.
3. The neighbors' record. EPA's ECHO has compliance and enforcement information "for more than one million regulated facilities nationwide."
4. Underground storage tanks. EPA's UST Finder maps tanks and tank releases nationwide. Its state data is from 2018 and 2019, so check the state as well. California's GeoTracker tracks leaking underground storage tank cleanups and other cleanup sites. Texas publishes its leaking petroleum storage tank sites as a searchable dataset, updated daily.
5. Historical topographic maps. The USGS collection holds maps printed between 1884 and 2006, free through topoView. Compare editions. The map symbols include railroads and sidings, tanks, quarries, gravel pits, tailings and orchards.
6. Historical aerial photos. The USGS Aerial Photo Single Frames archive starts in 1937. Medium-resolution scans download free from EarthExplorer.
7. Fire insurance maps. The Library of Congress Sanborn collection is arranged by state and city. The Library says it depicts "some twelve thousand cities and towns" from 1867 on, so a rural tract may have none.

Give what you find to the consultant, with dates and links. Section 312.28 requires the buyer's own knowledge of the property and the surrounding area to be taken into account.

Pillar's map layers show floodplain, wetlands and other mapped constraints over parcel boundaries, with coverage that varies by dataset. That is the first pass in our desktop site screening checklist, and it is not an environmental assessment.

Do I need a Phase 1 for vacant land?

If you want the CERCLA protections, or your lender requires one, yes. EPA's comparison says the rule applies "without limit to a particular land use." Oklahoma's fact sheet names "seemingly undeveloped land" among the properties where a Phase I matters most.

Vacant land is not automatically clean

• Former orchards. Washington's Department of Ecology says lead-arsenate pesticides were used in apple and pear orchards from "the late 1800s to just before 1950" and "left arsenic and lead in the soil." For building houses on former orchard land, Ecology says soil sampling is required "for all properties that were orchard land when lead arsenate was used." Ecology says many local governments will not issue final plat approval or an occupancy permit until a required remedy is in place.
• Old farm and heating oil tanks. Federal tank rules do not cover farm and residential tanks of 1,100 gallons or less holding motor fuel for noncommercial purposes, or tanks storing heating oil used on the premises. A tank outside the federal rules may be missing from federal tank records. EPA notes that some state and local authorities regulate these tanks, so their records may still show one, and the historical research, the site visit and the owner interview are the other ways to find it.
• Fill and dumping. E1527-21 treats the placement of fill dirt as a use to research. An ALTA survey can add a field check: Table A item 8 covers "substantial areas of refuse," as our ALTA survey guide explains.
• PFAS. EPA's 2022 comparison said substances not yet defined as CERCLA hazardous substances, PFAS among them, were outside a Phase I's scope. EPA has since designated PFOA and PFOS, effective July 8, 2024. Ask the consultant how the report treats them.

When to order it, and what a REC does to the deal

Order it early. ECS, a consulting firm, says the process is "most effective when performed at the start of a transaction's due diligence period." A REC found in the last week leaves no time for a Phase II. On a contract with a long entitlement period, an early Phase I will be stale by closing, so budget for an update. Our land feasibility study guide places it among the other studies.

Ohio EPA lists a buyer's options when a property turns out to be contaminated. They include not buying, asking the owner to clean it up first, and negotiating a lower price to reflect cleanup costs. For an SBA loan, if the professional concludes that further investigation is warranted, the lender "must proceed as recommended by the Environmental Professional" or ask the SBA for an exception.

What a Phase 1 does not cover

Ohio EPA says the assessment "won't identify all environmental considerations for the property, such as the presence of wetlands." The Mansfield report lists what its consultant treated as outside the standard's scope, including "asbestos-containing materials, radon, lead-based paint, lead in drinking water, wetlands," "endangered species" and "mold." ASTM's scope says such items can be added if the buyer and the consultant agree before the work starts.

For a land purchase, wetlands are the item to plan for, and our wetland delineation guide covers that study. Soil suitability is a separate question from contamination, covered in our soil survey guide.

Where it shows up in the deal documents

• Purchase contract. The right to enter for the site visit, and a due diligence period long enough for a Phase II.
• Title commitment. The lien search is title work. Our title commitment guide notes that the standard commitment's definition of public records excludes environmental protection records, so ask the title company what its search covers. Holland & Knight quotes E1527-21 as saying that a title search information report must review land title records "for documents recorded between 1980 and the present," and says the standard also accepts title insurance documents prepared for the deal.
• Loan file. The SBA requires a reliance letter from the environmental professional with every Phase I, so tell the consultant who the lender is before the report is issued.

Before you make an offer

1. Run the free pre-check above and save what you find.
2. Ask the seller for earlier environmental reports, tank records and agency closure letters.
3. Ask the lender which investigation it requires and how it dates the report.
4. Ask the consultant which standard fits the tract, E1527-21 or E2247-23, and confirm the signer meets the section 312.10 definition.
5. Ask for the five component dates in writing and check them against the expected closing date.

Quick answers

How long is a Phase 1 ESA good for? Under 40 CFR 312.20, the inquiry must be done within one year before the buyer takes title, and five components must be done or updated within 180 days before.

How much does a Phase 1 ESA cost? Published figures run from Iowa DNR's $2,000 to $3,000 average to the Oklahoma Corporation Commission's $1,500 to $12,000. Ohio EPA says $2,000 to $6,000 is typical.

How long does a Phase 1 ESA take? Two consulting firms publish figures of two to four weeks and three to four weeks.

What is the difference between Phase 1 and Phase 2? A Phase I reviews records and inspects the site. A Phase II takes samples to confirm whether contamination is present.

Can I use the seller's Phase 1 report? Section 312.20 allows it if the report meets the rule's objectives, the buyer adds their own inquiries, and the one-year and 180-day limits are met. Whether the consultant lets you rely on it is a contract question.