We have completed hundreds of Environmental Site Assessments (ESAs) for commercial, mixed-use and industrial properties across Central and Northern California.  Our assessments conform to the American Society for Testing and Materials’ (ASTM) standards for Phase I and Phase II ESAs, as well as the US EPA’s All Appropriate Inquiries guidance for Environmental Site Assessments.  Weber, Hayes and Associates is prepared to complete an ESA for your site in accordance with the following standards:

Phase I Environmental Site Assessments

The purpose of the Phase I ESA is to provide a professional opinion regarding environmental risk conditions at a property, including potential impacts from documented environmental releases in the surrounding area. The term “recognized environmental conditions” or REC, is defined as “the presence or likely presence of any hazardous substances or petroleum products in, on, or at a property: (1) due to release to the environment; (2) under conditions indicative of a release to the environment; or (3) under conditions that pose a material threat of a future release to the environment. De minimis conditions are not recognized environmental conditions.” (ASTM Standard E-1527 13)

Our services include:

  • Historical Database search of on-site and vicinity land uses. 
  • Interviews with parties knowledgeable about the property’s past.
  • Site Visit and Investigation.
  • A conclusive report identifying any potential Recognized Environmental Conditions.


While Phase I ESAs can only provide limited assurances of risk potential, as they rely on current site conditions (site inspections), cooperative and candid interviews/questionnaires, and a limited database of regulatory and historical documentation, they have become a standard means by which lending agencies, developers and property owners screen a property for environmental risks and determine whether further investigation is warranted.

The environmental professional provides opinions on each of the conditions identified during the research phase. These opinions of potential risk fall into three categories, as laid out by ASTM:

  • Recognized Environmental Conditions (REC)
  • Controlled Recognized Environmental Conditions (CREC)
  • Historical Recognized Environmental Conditions (HREC)
  • De minimis conditions

Based on the conclusions of the Phase I ESA, Weber, Hayes and Associates may recommend that Phase II soil and groundwater sampling be conducted to determine whether the recognized environmental conditions identified have in fact caused a significant release to soil or groundwater beneath the property. Generally speaking, Weber, Hayes and Associates can provide this recommendation within a week after initiating Phase I research so that the purchaser of the ESA can decide if they wish to complete soil and groundwater sampling concurrently. This is done to meet the often narrow time-frames involved with property transactions and Escrow.

Phase II Environmental Site Assessments

Weber, Hayes, and Associates has also completed hundreds of Phase II environmental assessments across Central and Northern California. These soil and groundwater assessments are conducted for multiple reasons, but most often in response to recognized environmental conditions identified during Phase I ESA research. Sampling strategies designed for Phase II ESAs are catered to the site-specific high-risk locations identified for the property, and incorporate knowledge of soil/geological conditions, groundwater depth and flow direction, site infrastructure and potential future land-use changes.

Depending on land-usage, a Phase II investigation may target soil, groundwater and also soil vapor for sampling. When there is evidence of either shallow soil or groundwater contamination involving volatile organic compounds (VOCs) beneath buildings or enclosed spaces that humans regularly occupy, the risk associated with long-term exposure to VOCs must be evaluated. Weber, Hayes and Associates has extensive experience with installing temporary soil vapor probes in the event that Vapor Encroachment Conditions are identified [see ASTM E2600-10 for the definition of a Vapor Encroachment Condition (VEC)].

Combined Assessments

When a prospective purchaser or property owner has already noted strong indications of a potential release of petroleum products or hazardous materials to soil or groundwater beneath a property, they sometimes wish to directly proceed to completing a combined Phase I/II assessment. In these cases, there is some reduction in cost and project management, thereby fitting into more narrow Escrow deadlines.