Chapter: What is the primary purpose of a Phase I Environmental Site Assessment? (EN)

Chapter: What is the primary purpose of a Phase I Environmental Site Assessment? (EN)

1. Defining the Primary Purpose: Identifying Potential Environmental Liabilities

The primary purpose of a Phase I Environmental Site Assessment (ESA) is to identify Recognized Environmental Conditions (RECs) at a property. These RECs represent potential or existing environmental liabilities associated with the property’s past or current use. A Phase I ESA is NOT designed to definitively determine the presence or absence of contamination, but rather to assess the potential for contamination. This assessment informs decisions related to property transactions, redevelopment, and risk management. It acts as a preliminary screening tool.

2. Understanding “Recognized Environmental Conditions” (RECs)

RECs are defined as the presence or likely presence of any hazardous substances or petroleum products on a property under conditions that indicate an existing release, a past release, or a material threat of a release of any hazardous substances or petroleum products into structures on the property or into the ground, ground water, or surface water of the property.

• Existing Release: Documented evidence of contamination already present.
• Past Release: Documented evidence of a previous release that may or may not have been remediated.
• Material Threat of a Release: Conditions indicating a high likelihood of a future release.

3. The All Appropriate Inquiry (AAI) Rule and CERCLA Liability Protection

The Phase I ESA is a critical component of the All Appropriate Inquiry (AAI) rule, as defined by the U.S. Environmental Protection Agency (EPA) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund. Performing a compliant Phase I ESA is a key step towards establishing one of the landowner liability protections (LLPs) under CERCLA. Specifically, it allows a prospective purchaser to demonstrate that they have performed “all appropriate inquiry” into the previous ownership and uses of the property. The LLPs under CERCLA include:

• Innocent Landowner Liability Protection: Available to parties who acquire property without knowledge of existing contamination and have performed all appropriate inquiry.
• Contiguous Property Owner Liability Protection: Available to owners of properties adjacent to a contaminated site who did not cause or contribute to the contamination.
• Bona Fide Prospective Purchaser Liability Protection: Available to parties who purchase contaminated property with knowledge of the contamination, but who are not liable under CERCLA because they meet specific requirements, including performing all appropriate inquiry.

4. Scientific Principles Underpinning Phase I ESA Investigations

The Phase I ESA relies on several scientific principles related to environmental fate and transport.

• Source Identification: Identifying potential sources of contamination based on historical land use. This involves applying knowledge of industrial processes and waste management practices.

• Migration Pathways: Understanding how contaminants move through the environment. Key pathways include:

  • Groundwater Flow: Described by Darcy’s Law:

    $Q = -KA(dh/dl)$

    Where:
    * Q is the volumetric flow rate of groundwater.
    * K is the hydraulic conductivity of the soil or aquifer.
    * A is the cross-sectional area through which the flow occurs.
    * dh/dl is the hydraulic gradient (change in head over distance).

  • Soil Vapor Intrusion: Understanding the diffusion of volatile organic compounds (VOCs) from contaminated soil or groundwater into buildings. Fick’s First Law of Diffusion can be applied:

    $J = -D (dC/dx)$

    Where:
    * J is the diffusion flux.
    * D is the diffusion coefficient.
    * dC/dx is the concentration gradient.

  • Surface Water Runoff: Analyzing topographic maps and drainage patterns to assess the potential for contaminant transport via surface water.

• Receptor Identification: Identifying potential receptors (e.g., human populations, sensitive ecosystems) that could be exposed to contaminants.

• Chemical Properties: Understanding the physical and chemical properties of potential contaminants, such as solubility, volatility, and toxicity, to predict their behavior in the environment. For example, the octanol-water partition coefficient ($K_{ow}$) describes the partitioning of a chemical between octanol (a surrogate for lipids) and water. Chemicals with high $K_{ow}$ values tend to bioaccumulate.
• Geological and Hydrogeological Characterization: Reviewing geological maps, soil surveys, and well logs to understand the subsurface geology and hydrogeology of the site.

5. Components of a Phase I ESA: Data Collection and Analysis

The Phase I ESA involves several key components:

1. Records Review:

   • Historical Aerial Photographs: Analyzing aerial photos to identify past land uses and potential sources of contamination (e.g., storage tanks, waste disposal areas).
   • Sanborn Maps: Reviewing fire insurance maps to identify historical building layouts, including potential sources of contamination.
   • City Directories: Identifying past occupants of the property and their associated businesses.
   • Environmental Regulatory Databases: Searching federal, state, and local databases for information on known environmental violations, permitted facilities, and contaminated sites in the vicinity of the property. Examples include:
     • EPA’s Envirofacts database: Contains information on Superfund sites, hazardous waste generators, and air and water pollution permits.
     • State environmental agency databases: Contain information on state-specific environmental regulations and enforcement actions.
   • Local Government Records: Reviewing building permits, fire department records, and other local government records for information on past or present uses of the property.

2. Site Reconnaissance: A visual inspection of the property to identify potential environmental concerns, such as:

   • Stained soil or vegetation: Indicating potential spills or leaks.
   • Unidentified containers: Potentially containing hazardous substances.
   • Wastewater discharges: Potentially contaminating surface water.
   • Aboveground or underground storage tanks (ASTs/USTs): Posing a risk of leaks or spills.
   • Evidence of past industrial activities: Such as abandoned equipment or process areas.

3. Interviews:

   • Current and past owners/operators: Gathering information on the history of the property and any known environmental issues.
   • Local government officials: Obtaining information on local environmental regulations and enforcement actions.
   • Neighbors: Gathering anecdotal information on past uses of the property and any observed environmental impacts.

4. Report Preparation: Compiling and analyzing all collected information into a written report. The report should:

   • Summarize the findings of the records review, site reconnaissance, and interviews.
   • Identify any RECs at the property.
   • Provide an opinion as to the potential environmental risks associated with the RECs.
   • Recommend further investigation (e.g., a Phase II ESA) if necessary.

6. Practical Applications and Related “Experiments” (Case Studies)

Although a Phase I ESA doesn’t involve physical sampling, analyzing data gathered can be viewed as akin to an observational experiment.

• Case Study 1: Former Gas Station: A Phase I ESA identifies a former gas station on the property based on historical Sanborn maps and city directories. The presence of USTs, combined with the knowledge of gasoline contamination potential, leads to the identification of an REC. A Phase II ESA (sampling and analysis) would then be recommended to confirm the presence and extent of contamination.
• Case Study 2: Industrial Site with Solvent Use: A Phase I ESA reveals that the property was previously used as a manufacturing facility that used solvents for cleaning and degreasing. Database searches reveal a history of solvent spills at neighboring properties. These findings indicate a potential for soil and groundwater contamination. The Phase I ESA identifies an REC based on the potential for solvent contamination.
• Case Study 3: Agricultural Land with Pesticide Use: A Phase I ESA reveals that the property was historically used for agriculture. The Phase I ESA identifies potential RECs related to pesticide and herbicide application and runoff based on the application rates and chemical properties of commonly used pesticides.

7. Evolution and Impact: From Awareness to Standard Practice

The use of Phase I ESAs has evolved significantly since the enactment of CERCLA. Initially, environmental due diligence was less standardized. Today, standardized practices outlined in ASTM standards (e.g., ASTM E1527-21) are widely adopted. This standardization has:

• Reduced uncertainty in environmental risk assessment.
• Facilitated real estate transactions by providing a consistent framework for evaluating environmental liabilities.
• Improved environmental stewardship by encouraging responsible property management.
• Increased awareness of environmental issues among property owners and developers.

8. Conclusion

The primary purpose of a Phase I Environmental Site Assessment is to identify Recognized Environmental Conditions (RECs) at a property, serving as a critical first step in evaluating potential environmental liabilities and informing decisions related to property transactions, redevelopment, and risk management. Successfully completing a Phase I ESA, adhering to AAI standards, enables a prospective purchaser to qualify for LLPs under CERCLA.