Scrutiny of the land includes examination of potential soil contamination, groundwater quality, surface water quality, vapor intrusion, and sometimes issues related to hazardous substance uptake by biota.  The examination of a site may include: definition of any chemical residues within structures; identification of possible asbestos containing building materials; inventory of hazardous substances stored or used on site; assessment of mold and mildew; and evaluation of other indoor air quality parameters.
Depending upon precise protocols utilized, there are a number of variations in the scope of a Phase I study.  The tasks listed here are common to almost all Phase I ESAs:
* Performance of an on-site visit to view present conditions (chemical spill residue, die-back of vegetation, etc.); hazardous substances or petroleum products usage (presence of above ground or underground storage tanks, storage of acids, etc.);  and evaluate any likely environmentally hazardous site history.
*Evaluation of risks of neighboring properties upon the subject property
*Review of Federal, State, Local and Tribal Records out to distances specified by the ASTM 1528 and AAI Standards (ranging from 1/8 to 1 mile depending on the database)
* Interview of persons knowledgeable regarding the property history (past owners, present owner, key site manager, present tenants, neighbors).
*Examine municipal or county planning files to check prior land usage and permits granted.
*Conduct file searches with public agencies (State water board, fire department, county health department, etc.) having oversight relative to water quality and soil contamination issues.
*Examine historical aerial photography of the vicinity.
*Examine current USGS maps to scrutinize drainage patterns and topography.
*Examine chain-of-title for Environmental Liens and/or Activity and Land Use Limitations (AULs).
In most cases, the public file searches, historical research and chain-of-title examinations are outsourced to information services that specialize in such activities. Non-Scope Items in a Phase I Environmental Site Assessment can include visual inspections or records review searches for:
*Asbestos Containing Building Materials (ACBM)
*Lead-Based Paint
*Lead in Drinking Water
*Mold
*Radon
*Wetlands
*Threatened and Endangered Species
*Mercury poisoning
*Debris flow
*Earthquake Hazard
*Vapor intrusion
*Emerging contaminants
Observations of Non-scope Items can be reported as "findings" if requested by the report user, however, these items do not constitute recognized environmental conditions.