The conclusion section of a Phase I Environmental Site Assessment (ESA) is where analysis turns into professional judgment. After pages of records review, site reconnaissance, and interviews, the conclusion delivers what stakeholders care about most: Is there environmental risk, and what should be done next?
A strong conclusion is not just a summary—it is a clear, defensible opinion supported by evidence. It must align with recognized standards such as ASTM E1527-21 and CSA Z768-01, ensuring consistency, clarity, and regulatory compliance.
This guide provides a detailed breakdown of the key components of an effective Phase I ESA conclusion, along with practical tips to improve clarity, defensibility, and value for clients.
Why the Conclusion Section Matters
The conclusion is often the most read section of the entire report. It is relied upon by:
- Property purchasers
- Lenders and financial institutions
- Legal advisors
- Regulators
- Developers and investors
These stakeholders may not read the full report—but they will read the conclusion carefully.
The Role of the Environmental Professional (EP)
The conclusion reflects the professional opinion of the environmental professional (EP), who must:
- Interpret complex and sometimes incomplete data
- Apply professional judgment
- Communicate findings clearly and objectively
A poorly written conclusion can:
- Create confusion
- Increase liability
- Undermine confidence in the assessment
A well-written conclusion does the opposite—it provides clarity, direction, and confidence.
Summary of Findings
The conclusion should begin with a brief summary of key findings.
This is not a full recap of the report—it is a transition into the EP’s final opinion.
What to Include
Summarize findings from:
- Records review
- Site reconnaissance
- Interviews (owners, government, neighbors)
Example
“Based on the records review, site reconnaissance, and interviews conducted, the subject property has historically been used for commercial purposes, including a former automotive repair facility. No evidence of current hazardous material storage was observed; however, historical use suggests the potential for petroleum-related impacts.”
Best Practices
- Keep it concise (1–2 paragraphs)
- Focus on material findings only
- Avoid introducing new information
Opinion on Recognized Environmental Conditions (RECs)
This is the core of the conclusion and the most critical element of the Phase I ESA.
Under ASTM E1527-21, a Recognized Environmental Condition (REC) is:
The presence or likely presence of hazardous substances or petroleum products due to a release, a likely release, or a material threat of a future release.
A. Use Clear and Direct Language
Avoid vague or hedging language.
❌ Weak:
- “There may be some concerns…”
- “Potential issues could exist…”
✅ Strong:
- “No evidence of recognized environmental conditions was identified.”
- “The historical operation of a gasoline service station is identified as a recognized environmental condition.”
B. Clearly State Your Opinion
Your conclusion should answer:
👉 Are RECs present or not?
C. Classification of Conditions
The conclusion should clearly identify and classify:
1. Recognized Environmental Conditions (RECs)
- Current or likely contamination risk
2. Historical Recognized Environmental Conditions (HRECs)
- Past contamination that has been remediated to regulatory standards
3. Controlled Recognized Environmental Conditions (CRECs)
- Contamination managed under controls (e.g., risk management measures)
Example
“The former underground storage tank (UST) system is identified as a recognized environmental condition due to the potential for historical releases of petroleum hydrocarbons.”
D. De Minimis Conditions
These are minor conditions that do not pose a material risk.
Example:
- Small quantities of household chemicals
- Minor staining not indicative of contamination
Example Statement
“Minor staining observed near the maintenance area is considered a de minimis condition and does not represent a recognized environmental condition.”
Discussion of Data Gaps
Data gaps are unavoidable in many Phase I ESAs. The key is transparency and evaluation.
What Is a Data Gap?
A data gap is missing or incomplete information that affects the EP’s ability to identify RECs.
Examples include:
- Missing historical records
- Inaccessible areas of the property
- Unavailable interviewees
- Limited regulatory data
Requirements
The conclusion must:
- Identify significant data gaps
- Explain their relevance
- Assess their impact on the findings
Example
“A data gap was identified due to the unavailability of historical fire insurance plans prior to 1950. This gap is not considered significant, as other sources provided sufficient information regarding historical land use.”
When Data Gaps Are Significant
If a data gap limits your ability to assess risk, this must be clearly stated.
Recommendations for Further Action
The conclusion must provide clear, actionable recommendations.
This is where the report shifts from analysis to decision-making.
A. No Further Action
If no RECs are identified:
“Based on the findings of this assessment, no further environmental investigation is recommended.”
B. Phase II ESA Recommended
If RECs are identified:
“A Phase II Environmental Site Assessment is recommended to evaluate the presence and extent of potential soil and groundwater contamination.”
C. Other Recommendations
Depending on the scope, additional recommendations may include:
- Designated substance surveys (e.g., asbestos, lead)
- Risk management measures
- Monitoring programs
- Additional record searches
Best Practices
- Be specific and direct
- Avoid ambiguous recommendations
- Ensure recommendations align with findings
Integration of Findings
A strong conclusion connects all lines of evidence:
- Records review
- Site reconnaissance
- Interviews
- Regulatory data
Why This Matters
Environmental risk assessment is not based on a single data point—it is based on converging evidence.
Example
“The identification of a former automotive repair facility is supported by historical records, site observations, and information obtained during interviews, reinforcing the conclusion that a recognized environmental condition is present.”
Reliance and Limitations
The conclusion should reiterate key limitations and reliance conditions.
A. Reliance Parties
Specify who can rely on the report:
- Client
- Lender
- Other approved parties
B. Limitations
Clarify that:
- The assessment is based on available information
- Conditions may change over time
- The report is subject to defined scope limitations
Example
“This assessment is based on information available at the time of the investigation and is subject to the limitations outlined in this report.”
Professional Certification
The conclusion must be supported by a qualified environmental professional.
Typical Credentials
- Professional Engineer (P.Eng.)
- Professional Geoscientist (P.Geo.)
Why Certification Matters
- Confirms professional accountability
- Enhances credibility
- Meets regulatory and legal requirements
Writing Style and Structure
A strong conclusion is not just technically correct—it is clear and readable.
A. Be Concise
Avoid unnecessary detail.
- Focus on key findings
- Keep language direct
B. Avoid Ambiguity
Clarity is critical.
- Use definitive statements
- Support conclusions with evidence
C. Maintain Professional Tone
- Objective
- Neutral
- Evidence-based
D. Use Structured Formatting
Organize the conclusion into:
- Summary of findings
- REC determination
- Data gaps
- Recommendations
Common Mistakes to Avoid
1. Vague Language
Unclear conclusions reduce confidence and increase risk.
2. Inconsistent Findings
The conclusion must align with the body of the report.
3. Ignoring Data Gaps
Failure to address gaps can undermine defensibility.
4. Overly Long Conclusions
Keep it focused—this is not another report section.
5. Missing Recommendations
Every conclusion should provide a clear next step.
Practical Example of a Strong Conclusion
Below is a simplified example:
Conclusion
Based on the records review, site reconnaissance, and interviews conducted, the subject property has historically been used for commercial purposes, including an automotive repair facility.
The historical operation of the automotive repair facility is identified as a recognized environmental condition (REC) due to the potential for releases of petroleum hydrocarbons and solvents.
No evidence of current hazardous material storage was observed during the site inspection. Minor staining observed on-site is considered a de minimis condition and does not represent a REC.
A data gap was identified due to the lack of historical records prior to 1960; however, this gap is not considered significant.
Based on these findings, a Phase II Environmental Site Assessment is recommended to evaluate potential soil and groundwater impacts.
This report is prepared for the exclusive use of the client and is subject to the limitations outlined herein.
The Value of a Strong Conclusion
A well-written conclusion provides:
- Clarity for decision-makers
- Confidence in the assessment
- Direction for next steps
- Defensibility in legal and regulatory contexts
Conclusion
The conclusion section of a Phase I ESA is where technical analysis becomes actionable insight.
By following standards such as ASTM E1527-21 and CSA Z768-01, and by focusing on clarity, structure, and professional judgment, environmental professionals can deliver conclusions that are:
- Clear
- Defensible
- Actionable
- Trusted
Key Takeaways
- The conclusion is the most critical section of a Phase I ESA
- It must clearly state the presence or absence of RECs
- Data gaps must be identified and evaluated
- Recommendations must be direct and actionable
- Clarity and professionalism are essential
Final Thought
A Phase I ESA conclusion is more than a summary—it is a professional opinion that guides real-world decisions.
Whether determining property value, securing financing, or managing environmental risk, the strength of your conclusion directly impacts the value of your work.
In environmental due diligence, clarity is not just helpful—it is essential.
👉 Learn more about our Automated Environmental Site Assessment Solution
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