Phase I ESA Guide: Process, Requirements, Findings & Next Steps
Whether you're purchasing a commercial property, refinancing an existing asset, or reviewing lender requirements, understanding the Phase I Environmental Site Assessment process is an important part of commercial real estate due diligence. This guide explains how a Phase I ESA works, what environmental professionals evaluate under ASTM E1527-21, what Recognized Environmental Conditions (RECs) mean, when a Phase II Environmental Site Assessment may be recommended, and what happens after the report is complete.
Rather than focusing on one specific property or project, this guide provides a step-by-step overview of the Phase I ESA process and links to more detailed resources covering individual topics in greater depth.
Need a Phase I ESA for an active commercial real estate transaction?
→ Visit our Phase I Environmental Site Assessment Services page to learn how CRB supports acquisitions, financing, redevelopment projects, and environmental due diligence nationwide.
Understanding the Purpose of a Phase I ESA
A Phase I Environmental Site Assessment is a structured evaluation of a specific property’s current and historical environmental conditions. Its primary purpose is to identify if there are any Recognized Environmental Conditions, or RECs, associated with the property. A REC generally relates to the presence or likely presence of hazardous substances or petroleum products due to a release, a likely release, or conditions presenting a material threat of a future release.
A Phase I ESA is not intended to guarantee that a property is free from contamination. No environmental site assessment can eliminate all uncertainty. Instead, the assessment reduces uncertainty by assembling and evaluating information that is reasonably available within the scope, time, and cost limitations of the ASTM process. ASTM specifically recognizes that professional judgment is essential and that the appropriate level of inquiry may vary based on the property, its history, intended use, and information uncovered during the assessment. The final report gives the client a technically supported opinion regarding environmental conditions that could affect the transaction or warrant further investigation.
Why Are Phase I ESAs Important in Commercial Real Estate?
A Phase I ESA is only one component of the broader commercial real estate due diligence process. Depending on the transaction, buyers may also complete:
Property Condition Assessments (PCAs)
Appraisals
ALTA/NSPS Land Title Surveys
Zoning reviews
Flood evaluations
Geotechnical investigations
Building inspections
Financial due diligence
Lease reviews
Each assessment serves a different purpose. A building inspection evaluates the physical condition of structures. A Property Condition Assessment evaluates deferred maintenance and capital improvements. An appraisal estimates market value. A Phase I Environmental Site Assessment evaluates environmental risk associated with the property. Because environmental liability can significantly affect a property's value, financing, and future development, lenders frequently require environmental due diligence before closing commercial real estate transactions.
The Phase I ESA Process at a Glance
Although every property is different, most Phase I Environmental Site Assessments follow the same general process.
Step 1 — Project Scoping
The environmental consultant gathers information about the property, transaction, intended use, schedule, and client requirements.
This may include:
Property address
Parcel information
Current owner
Proposed purchaser
Intended property use
Lender requirements
Closing schedule
Available historical reports
Step 2 — Historical Research
Historical research helps environmental professionals understand how the property has changed over time.
Depending on availability, sources may include:
Historical aerial photographs
Sanborn Fire Insurance Maps
Historical topographic maps
City directories
Building permits
Property tax records
Historical land use records
Previous environmental reports
This research often identifies former operations that no longer exist but may still influence environmental conditions today.
Step 3 — Regulatory Records Review
Federal, state, tribal, and local environmental databases are reviewed to identify environmental records associated with the property and surrounding area.
Examples include:
Underground Storage Tanks (USTs)
Leaking Underground Storage Tanks (LUSTs)
Hazardous waste generators
Brownfield sites
Superfund sites
Spill records
Landfills
Corrective action facilities
Engineering controls
Institutional controls
A database listing alone does not mean contamination exists.
Each record must be evaluated within the context of the property's history, regulatory status, distance from the site, and professional judgment.
Step 4 — Site Reconnaissance
An environmental professional conducts a visual inspection of the property.
The purpose is to compare current site conditions with historical information while identifying potential environmental concerns that may not appear in available records.
The inspection typically includes:
Buildings
Parking areas
Loading docks
Mechanical rooms
Exterior grounds
Chemical storage areas
Waste handling areas
Utility areas
Property boundaries
The environmental professional documents observations with photographs and field notes that become part of the final report.
Step 5 — Interviews
Interviews provide information that may not be available through records research.
Depending on the property, interviews may include:
Current owners
Property managers
Facility managers
Occupants
Local government officials
Other knowledgeable individuals
Interview information is evaluated alongside historical research and field observations rather than independently.
Step 6 — Environmental Evaluation
Once all available information has been collected, the environmental professional evaluates the property's environmental history and current conditions.
This evaluation determines whether environmental conditions meet ASTM definitions for:
Recognized Environmental Conditions (RECs)
Controlled Recognized Environmental Conditions (CRECs)
Historical Recognized Environmental Conditions (HRECs)
De minimis conditions
Professional judgment plays a critical role during this stage.
The Phase I ESA is not simply a collection of database reports—it is an interpretation of all reasonably available environmental information.
Step 7 — Final Report
The completed report summarizes the investigation and explains the environmental professional's conclusions.
A typical report includes:
Property description
Historical research
Environmental database review
Site reconnaissance
Interview summaries
Findings
Environmental conclusions
Supporting photographs
Maps
Appendices
The report may conclude that:
No Recognized Environmental Conditions were identified.
or
One or more Recognized Environmental Conditions were identified that may warrant additional evaluation.
When Should a Phase I ESA Be Completed?
A Phase I ESA is typically performed before acquiring an interest in commercial real estate and early enough to allow time for further evaluation if a concern is identified. Common situations include:
Commercial property acquisition
A buyer may order a Phase I ESA during the due diligence period to assess environmental liability before closing.
Commercial real estate financing
A lender may require an environmental site assessment before approving or funding a loan, particularly when the property has a higher-risk use or history.
Refinancing
An existing owner may need an updated Phase I ESA when refinancing a property or changing lenders.
Redevelopment or change in use
A developer may order an assessment before demolition, excavation, redevelopment, or converting an industrial or commercial property to a more sensitive use.
Portfolio acquisitions
Investors acquiring multiple properties may use Phase I ESAs to identify environmental risks across the portfolio and prioritize properties requiring additional investigation.
Foreclosure or distressed assets
Lenders and investors may evaluate environmental conditions before taking control of a distressed or potentially contaminated site.
Property disposition
A seller may commission environmental due diligence to better understand potential concerns before bringing a property to market, although the report’s intended user, reliance provisions, and transaction strategy should be considered carefully.
What Does the Environmental Professional Evaluate?
The environmental professional reviews the collected information to determine whether the property is associated with environmental conditions requiring classification or further discussion.
The evaluation considers:
Current and historical use of the subject property
Uses of hazardous substances and petroleum products
Waste generation, handling, storage, and disposal
Reported releases or threatened releases
Regulatory investigations and cleanup activity
Conditions at adjoining or nearby properties
Potential migration of contamination
Engineering or institutional controls
Data gaps and their significance
The intended future use disclosed by the client
The environmental professional’s experience and judgment
The report should explain how the available evidence supports its conclusions. A strong Phase I ESA does more than reproduce database results. It interprets those results in relation to the property.
What Are Recognized Environmental Conditions?
A Recognized Environmental Condition, or REC, is one of the principal conclusions that may be identified in a Phase I ESA. In practical terms, a REC indicates that available information supports concern regarding a release, likely release, or material threat of a future release of hazardous substances or petroleum products at, on, in, or to the subject property.
Does a Phase I ESA Test for Contamination?
A standard Phase I ESA does not include collecting or analyzing:
Soil samples
Groundwater samples
Soil-gas samples
Indoor-air samples
Sediment samples
Drinking-water samples
Building-material samples
The Phase I ESA evaluates whether available information indicates a potential environmental concern. It does not ordinarily confirm contaminant concentrations or define the vertical and horizontal extent of a release. When physical testing is warranted, it is usually performed as part of a Phase II Environmental Site Assessment or another targeted investigation.
This distinction is important:
A Phase I ESA identifies potential environmental conditions. A Phase II investigation uses sampling and laboratory analysis to evaluate specific concerns.
A Phase I report should not describe a property as definitively “clean” simply because no RECs were identified. Likewise, a REC does not by itself prove that contamination is present. It identifies a condition that may require further evaluation.
What Types of Properties May Present Greater Environmental Complexity?
Any commercial property can warrant environmental due diligence, but some uses are more frequently associated with environmental risk. Examples include:
Gasoline stations
Dry cleaners
Automotive repair facilities
Trucking terminals
Manufacturing plants
Warehouses with chemical storage
Metal-plating facilities
Printing operations
Salvage yards
Agricultural properties
Golf courses
Bulk petroleum facilities
Former landfills
Rail corridors and rail-served industrial sites
Healthcare and laboratory properties
Properties with current or former underground storage tanks
Properties developed on undocumented fill
Sites near known contamination plumes
Brownfield and redevelopment properties
The presence of one of these uses does not automatically establish that the site is contaminated. It indicates that the property history and operating details may require closer evaluation. A seemingly low-risk office, retail, hotel, or multifamily property may also have a higher-risk historical use that is no longer visible.
What Happens If a Phase I ESA Identifies a REC?
A REC does not automatically terminate a transaction. The appropriate response depends on:
The nature of the concern
The quality of the supporting evidence
The property’s intended use
Regulatory history
The lender’s requirements
The buyer’s risk tolerance
The transaction schedule
Whether existing data adequately characterizes the condition
Possible next steps may include:
Reviewing additional records
Agency files, prior reports, tank-closure documents, cleanup records, or regulatory correspondence may clarify the condition.Completing a Phase II ESA
Soil, groundwater, soil-gas, or other media may be sampled to evaluate the specific REC.Obtaining a reliance letter or updating an existing report
An older environmental report may contain useful information but may not satisfy the current transaction’s timing, reliance, or ASTM requirements.Revising transaction terms
The parties may negotiate price, escrow, indemnification, cleanup responsibilities, access, or closing conditions with legal counsel.Developing a remediation or risk-management strategy
Confirmed contamination may require regulatory coordination, engineering controls, institutional controls, remediation, or long-term monitoring.Proceeding with documented risk acceptance
In some circumstances, a buyer or lender may determine that the condition is sufficiently understood and manageable.
The environmental consultant provides technical findings and recommendations. Legal interpretations, contractual protections, and decisions regarding CERCLA defenses should be addressed with qualified environmental counsel.
How Long Does a Phase I Environmental Site Assessment Take?
The timeline varies based on:
Property size
Number and type of buildings
Current and historical uses
Availability of historical records
Agency response times
Site-access coordination
Interview availability
Complexity of surrounding properties
Lender-specific requirements
The number of properties in the portfolio
Whether expedited service is requested
The work generally involves:
Confirming scope and reliance requirements
Receiving property and transaction information
Ordering records and historical sources
Coordinating and completing the site visit
Conducting interviews
Reviewing regulatory and historical information
Evaluating findings
Preparing the report
Completing senior technical review and quality control
A fast report is valuable only when the assessment remains thorough, defensible, and appropriate for the transaction. The proposal should clearly distinguish the expected report-delivery date from the date the proposal itself is issued.
→ For a more detailed discussion, see How Long Does a Phase I Environmental Site Assessment Take?
How Much Does a Phase I Environmental Site Assessment Cost?
There is no responsible universal price for every Phase I ESA. The cost can be affected by:
Property type
Acreage
Building square footage
Number of parcels
Number of structures
Industrial or operational complexity
Rural or remote location
Travel requirements
Historical research complexity
Agency-file review
Portfolio size
Lender or agency requirements
Turnaround time
Reliance requirements
Availability of prior reports
Scope additions
A small office property with a straightforward history should not necessarily be priced or scoped the same way as a former manufacturing facility, gasoline station, agricultural operation, large industrial campus, or multi-property portfolio. Be cautious when comparing environmental site assessment companies solely by price. A low proposal may omit important scope details, rely heavily on automated database output, provide insufficient senior review, exclude required reliance, or fail to account for the property’s complexity.
→ For a detailed breakdown, see How Much Does a Phase I Environmental Site Assessment Cost?
How Should You Choose an Environmental Site Assessment Company?
The quality of a Phase I ESA depends heavily on the qualifications, judgment, research, field observations, interpretation, and report review provided by the environmental consulting firm. ASTM requires the Phase I ESA to be performed by an environmental professional. EPA defines an environmental professional through specified combinations of relevant licensing or certification, education, and full-time experience. When evaluating environmental site assessment companies, consider:
Environmental-professional qualifications
Confirm that the work will be performed under the responsible charge of an individual who meets the applicable environmental-professional requirements.
Commercial real estate experience
The consultant should understand acquisitions, financing, redevelopment, lender expectations, due diligence periods, and the practical consequences of environmental findings.
Experience with the property type
An environmental consultant evaluating a complex industrial or contamination site should have experience beyond routine office and retail assessments.
Technical review
Ask whether reports undergo senior technical and quality-control review before issuance.
Clear conclusions
The report should explain why a condition is or is not considered significant rather than simply listing database records and observations.
Appropriate turnaround
The consultant should understand the transaction schedule while allowing sufficient time for records, fieldwork, analysis, and defensible reporting.
Geographic capability
For portfolios or multi-market clients, consistent standards and project coordination across locations can be important.
Phase II and remediation capability
A firm that also performs subsurface investigation, regulatory coordination, and remediation can help maintain continuity when additional work is needed.
Lender and client reliance
Confirm who may rely on the report and whether lender-specific language or reliance documentation must be included. The cheapest provider is not necessarily the most economical option if an incomplete or poorly supported report delays closing, requires rework, or fails lender review.
What Should a Phase I ESA Report Provide?
A well-prepared Phase I ESA report should give the client more than a compilation of records. It should provide:
A clear description of the property
The assessment scope and applicable standard
Current and historical use findings
Regulatory database findings
Site reconnaissance observations
Interview findings
User-provided information
Relevant adjoining-property information
Identified data gaps
An evaluation of environmental conditions
Clearly supported conclusions
REC, CREC, HREC, and de minimis classifications where applicable
Recommendations when additional evaluation is warranted
The environmental professional’s required declaration
Supporting maps, photographs, records, and appendices
The report should be understandable to a commercial real estate decision-maker while remaining technically sound and defensible.
Phase I Environmental Site Assessments From CRB
CRB Geological & Environmental Services provides Phase I Environmental Site Assessments for commercial real estate acquisitions, financing, redevelopment, portfolio transactions, and other environmental due diligence needs. Since 1992, CRB has supported developers, lenders, attorneys, investors, property owners, municipalities, and corporate real estate teams with environmental assessments designed to provide clear, technically defensible findings.
Our capabilities include:
ASTM E1527-21 Phase I Environmental Site Assessments
Commercial property environmental due diligence
Phase II Environmental Site Assessments
Soil and groundwater investigation
Environmental remediation and corrective action
Regulatory coordination and compliance
Brownfield and redevelopment support
Portfolio and multi-property assessments
Indoor air quality, mold, moisture, and asbestos services
When a property presents a potential environmental concern, CRB can support the process from initial due diligence through investigation, regulatory coordination, corrective action, and project closeout.