Recognized Environmental Conditions (RECs) and Historical Research
Defining a REC
A REC is the presence or likely presence of any hazardous substance or petroleum product on a property under conditions that indicate an existing release, a past release, or a material threat of a release. The definition has three prongs: existing release, past release, and material threat. Historical RECs (HRECs) are past releases that have been addressed to regulatory closure; controlled RECs are releases that are managed by controls such as institutional or engineering controls. De minimis conditions do not meet the REC threshold because they do not threaten human health or the environment.
Historical research method
The purpose of historical research is to reconstruct all past uses of the property and adjoining properties. Typical sources include aerial photographs (often from the 1920s onward), Sanborn fire insurance maps, USGS topographic maps, city directories, building permits, and historical topographic and plat maps. The environmental professional looks for former dry cleaners, auto repair, gas stations, printing, metal plating, landfills, and agricultural chemical use. Adjacent uses matter because contamination can migrate.
Traps in questions
Do not confuse HREC with REC: an HREC has been resolved to closure, while a controlled REC still requires ongoing controls. A former gas station on an adjoining property is often a REC because of the migration potential. Historical fill or former ponds can be RECs even without a documented release, if there is a material threat. Be careful with the term "material threat"-it requires more than speculation.
Worked example
Aerial photos show a 1950s service station at the subject property, later converted to retail. A state LUST file shows a leak closed in 1998 with residual soil contamination. The leak is a controlled REC if institutional controls remain, and the current use as retail does not eliminate the finding.