Phase I Environmental Assessments (Phase I ESA) are the first step in the environmental due diligence process.  A Phase I ESA is a review of available information regarding a property to determine the possibility contamination may be present.  The assessment includes a review of environmental databases, file reviews, interviews with regulators/property owners and a site

ASTM 1527-05 was the first ASTM standard recognized by U.S. EPA as meeting the requirements of the "All Important Inquiries Rule." (AAI)   AAI sets forth the standards and practices necessary for fulfilling the requirements to obtain liability protection (i.e. bona fide purchaser defense) under CERCLA section 101(35)(B).  Most Phase I proposals reference 1527-05.