Databases are updated only periodically. If an incident recently occurred at a neighboring property, the database may not contain the information yet. In addition, an environmental incident may have predated the databases, or it may not have been reported. During the review of maps and aerial photos, the investigator is limited to what is available. Sanborn maps are usually available only for areas in and immediately surrounding urban areas.
Aerial photographs are usually available, but the availability dates vary from area to area.
Even when performed by the most reputable consulting firms, Phase I ESAs have clear limitations. They do not state a property is free of contamination. I ESA's inherent limitations. RECs may not be exposed because of an inadequate knowledge base on the part of the consultant or an inappropriate level of inquiry. The value of performing a Phase I ESA in determining potential environmental risks is important, but its reliability often is overestimated.