Phase I Environmental Site Assessment Process (ASTM E1527)
The four components
A Phase I ESA under ASTM E1527 combines records review, site reconnaissance, interviews, and a report, all evaluated against the standard's defined terms. The goal is to identify recognized environmental conditions (RECs), controlled RECs, and historical RECs, plus de minimis conditions that are not RECs. The environmental professional must exercise professional judgment and satisfy the definition of environmental professional in the standard.
Records and regulatory review
Review federal and state databases within the specified search distances: the NPL and CERCLIS-type lists at a one-mile radius, RCRA generators and handlers at the property and adjoining properties, and LUST/UST and voluntary cleanup lists at the specified distances. Review historical sources, including aerial photographs, topographic maps, fire insurance maps (Sanborn), city directories, and chain-of-title records, to reconstruct prior uses. Physical setting sources (USGS topographic maps, soil surveys, well logs) inform migration potential.
Site reconnaissance and interviews
Walk the property and observe adjoining properties, noting stains, drums, sumps, pits, ponds, lagoons, stressed vegetation, and fill. Interview the owner, occupants, and local officials where appropriate. The user has obligations too: provide specialized knowledge, commonly known information, and the purchase price, and conduct a title search.
Traps
A Phase I does not sample; it is non-intrusive. Data gaps must be identified and their significance evaluated. The standard has a shelf life: the report is presumed valid for one year, with certain components updated within 180 days. Vapor intrusion and PFAS are not automatically RECs; they require site-specific evidence.
Rule of thumb
If there is an obvious release or a government notification, the finding is likely a REC, not a de minimis condition.