Phase 1 Environmental Site Assessment California


A Phase I Environmental Site Assessment is an integral part of any commercial property real estate transaction. The Phase I Environmental site assessment report provides an analysis of a property’s past and current uses and outlines any environmental site conditions that may pose a liability for the current property owner or prospective purchaser.

Anyone who plans to buy or sell commercial real estate in California should obtain a Phase I Environmental Site Assessment. Such environmental inspections are an important requirement to protect prospective purchasers from environmental liability. The Phase I Environmental Site Assessment will analyze the risks associated with a property and identify any potential environmental cleanup needed on and around the property. Getting an accurate environmental site assessment report is essential to protect both the owner and the investor/prospective purchaser.

Our Phase I Environmental Site Assessment is completed by experienced staff and all are directed by environmental site professionals with a minimum of 10-year’s experience. Our projects are very cost-effective because we are a mid-size company company and we do not have the large overhead and expenses of a large company. We have the available staff and experience to complete multi-site portfolios with very short due dates. We take pride in the fact that we can provide quality Phase 1 ESA reports for less cost than our competition.

RSB Environmental is the national leader in Phase I Environmental Site Assessments by volume. Most reports are performed to meet the standards of ASTM E1527-21. RSB Environmental often customizes reports to meet individual client or agency lenders’ (Fannie Mae, Freddie Mac) requirements while taking the widely varying geology and topography of the state into consideration.

Phase 1 Environmental Site Assessment in California Scope:

Conducting a Phase 1 Environmental Site Assessment (ESA) in California is an essential aspect of due diligence for any property transaction. The process involves a comprehensive review of records, a thorough site inspection, and interviews with key stakeholders such as owners, occupants, neighbors, and local government officials.

During the assessment, our experienced team of environmental professionals adheres to the standard ASTM E1527-21 guidelines, which are widely accepted by regulatory agencies and lending institutions in California. This ensures that the assessment is conducted in accordance with industry standards.

It’s important to note that while laboratory analysis and sampling may not always be included in this phase of the assessment, they may be conducted as necessary, depending on the specific cases and findings.

During the assessment, our team will also investigate any potential contamination that may have resulted from activities on the site or nearby properties. Public records are reviewed and interviews are conducted to gather information about properties that have been classified as contaminated by federal or state regulations. The proximity of these contaminated sites to your property is also considered, as contamination may have spread to your site. To ensure a quality assessment, it is important to plan and allocate sufficient time for the process.

Site Visit

Historical Research

Geology and Hydrogeology

Regulatory Research

Interviews and Document Review

Our Service Areas

RSB has conducted Phase 1 Environmental Site Assessment projects nationwide. Locally RSB has completed numerous projects in California. Please feel free to call us at 1-832-291-3473 or email to get a site-specific price for your property.

Frequently Asked Questions

The cost of a Phase 1 Environmental Site Assessment (ESA) in California can vary, but generally ranges from $2,000 to $5,000. Factors that can affect the cost include the size and complexity of the property, the number of buildings or structures on the site, the type of contaminants present, and any special requirements needed for sampling. Location and consulting firm qualifications and experience may also play a role in determining the cost.


A Phase 1 Environmental Site Assessment (ESA) examines a property’s history and surroundings to identify the likelihood of environmental contamination. Before buying, financing, or developing a property, the first step is assessing its environmental status. It is a non-intrusive desk study that reviews historical documentation and visits the property to assess its condition. It also evaluates any recorded or known environmental issues on the property or vicinity, investigates the potential for contamination from neighboring properties or nearby sources, and reviews any applicable environmental legislation or recommendations. Phase 1 ESAs identify property environmental liabilities and urge additional action.


A Phase 1 Environmental Site Assessment (ESA) is a non-invasive study that includes a review of historical documents and aerial photographs, a site visit to observe the property’s current condition, an evaluation of any reported or known environmental incidents, investigation of potential contamination from neighboring properties or nearby sources, review of relevant environmental regulations and guidelines, the assessment of potential environmental risks and recommendations.


A Phase 1 Environmental Site Assessment (ESA) is typically triggered by a proposed or planned change in the use or ownership of a property, such as:

  • Property purchase
  • Financing a property
  • Developing a property
  • Leasing a property
  • Environmental regulations
  • Insurance requirement It may also be mandatory by law in certain locations before buying or developing a property


The jurisdiction and property regulations determine the “good for” period for a Phase 1 Environmental Site Assessment (ESA). Phase 1 ESAs often provide a picture of the property’s environmental status. Thus, the site’s changes since the assessment must be considered.

Unless new information or conditions change, a Phase 1 ESA is valid for 12 months after completion. Some jurisdictions have shorter or longer assessment validity periods. To verify the assessment, check with the authorities.

If the property undergoes major modifications, such as new construction or land usage, a Phase 1 ESA should be performed to ensure compliance.



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