ESS pioneered Phase I Environmental Site Assessments (ESA) beginning in 1988.  ESS developing a Phase 1 scope of work for large corporate clients and financial institutions.  Database inquiries were requested directly from the EPA and an encrypted Fortran printout was delivered.  ESS interpreted the coding and presented the relevant information in table format and ultimately generated the first graphical radius site maps prepared by hand.  The Resolution Trust Corporation (RTC) and SAMDA contractors became involved with these properties and adopted this scope of work.  This scope became the early Phase 1 Standard and was circulated nationwide.  It was later modified by RTC to satisfy additional National Environmental Policy Act (NEPA) requirements. 

The American Society for Testing Standards (ASTM) Standards committee developed a scope pairing back the RTC scope.  The ASTM Standard E1527-97 and 2000 defined a generally accepted scope balanced to satisfy financial and CERCLA liability concerns by conducting "all appropriate inquiries".

The EPA adopted the ASTM standards as their interim standard which became effective January 11, 2002.  November 1, 2005 Congress established the EPA's final rule (40 CFR Part 312) as the Standards and Practices for All Appropriate Inquiries; Final Rule.  This rule becomes effective November 6, 2006

Resolution Trust Corporation (RTC)
  Acted as an extension to RTC Staff for Program Management
REIT Holdings
  Environmental Baseline Studies (EBS) for portfolio of investment properties
Investors
  Phase I ESAs for investors and lending institutions