Flood and environmental due diligence glossary
The words that show up in flood maps, Phase I reports and lender checklists, in plain English, with what each one means for a buyer.
Flood zones and flood maps
- Flood zone AE
- Zone AE is a high-risk flood area on FEMA's maps: land with at least a 1% chance of flooding in any year, where FEMA has calculated how high the water is expected to rise (the base flood elevation).
- Flood zone X
- Zone X is FEMA's label for moderate and low flood risk. Shaded X is roughly the 500-year floodplain (0.2% annual chance). Unshaded X is outside it. Flood insurance is not required by lenders in either.
- Flood zone A
- Zone A is a high-risk flood area (1% annual chance) where FEMA has not calculated a base flood elevation. It is usually mapped with an approximate study.
- Flood zone VE
- Zone VE is a coastal high-hazard area: land in the 1% annual-chance flood that also faces waves of 3 feet or more. FEMA has published a base flood elevation that includes the wave height.
- 100-year floodplain
- A 100-year floodplain is land with a 1% chance of flooding in any given year. It does not mean the land floods once every hundred years.
- 500-year floodplain
- A 500-year floodplain is land with a 0.2% chance of flooding in any year. FEMA maps it as shaded zone X (zone B on older maps).
- Base flood elevation
- Base flood elevation (BFE) is the height floodwater is expected to reach in the 1% annual-chance flood, shown on FEMA's maps in AE, AH and VE zones.
- Special Flood Hazard Area
- A Special Flood Hazard Area is the land FEMA maps in the 1% annual-chance flood. It covers zones A, AE, A1-A30, AH, AO, AR, A99, V, VE and V1-V30.
- Regulatory floodway
- A regulatory floodway is the channel of a river or stream plus the nearby land that must be kept open to carry the 1% annual-chance flood without raising the water more than a set height, usually one foot.
Environmental due diligence
- Phase I environmental site assessment
- A Phase I environmental site assessment is a study of a property's past and present uses, done by an environmental professional, to find likely contamination before a purchase. It looks and asks; it does not sample.
- Phase II environmental site assessment
- A Phase II environmental site assessment tests the conditions a Phase I flagged by sampling soil, groundwater or soil vapor and sending them to a lab.
- Recognized environmental condition (REC)
- A recognized environmental condition (REC) is a Phase I finding that hazardous substances or petroleum are present at a property because of a release, are likely present because of one, or pose a material threat of a future release.
- Controlled REC (CREC)
- A controlled REC is a past release that was addressed to a regulator's satisfaction, but with contamination allowed to remain under controls, such as a ban on residential use, a cap, or a limit on groundwater wells.
- Historical REC (HREC)
- A historical REC is a past release that was cleaned up to a regulator's satisfaction for unrestricted use, with no controls left on the property.
- De minimis condition
- A de minimis condition is a minor issue, such as a small oil stain on pavement, that generally poses no threat to health or the environment and wouldn't be the subject of enforcement if regulators saw it.
- All Appropriate Inquiries
- All Appropriate Inquiries (AAI) is EPA's rule (40 CFR Part 312) for the environmental due diligence a buyer must do before buying a property to qualify for liability protections under federal cleanup law.
- Underground storage tank (UST)
- An underground storage tank (UST) is a tank, plus its connected piping, with at least 10% of its volume below ground. Most hold petroleum, like gasoline, diesel or heating oil.
- Leaking underground storage tank (LUST)
- A LUST site is a property where a state confirmed a release from an underground storage tank. Each one gets a case number and a status: open while cleanup continues, closed once the state is satisfied.
- Vapor intrusion
- Vapor intrusion is when vapors from contaminated soil or groundwater move up through the ground and into a building's indoor air.
- Sanborn maps
- Sanborn maps are detailed fire insurance maps of US cities and towns, made from the late 1800s through much of the 1900s. They show each building's outline, construction and use, down to gasoline tanks.
- CERCLA (Superfund)
- CERCLA, the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, is the federal Superfund law. It lets EPA clean up contaminated sites and make responsible parties pay, including current owners.
- Brownfield
- A brownfield is a property whose expansion, redevelopment or reuse may be complicated by the presence or potential presence of contamination.
- RCRA
- RCRA, the Resource Conservation and Recovery Act of 1976, is the federal law that governs hazardous waste from the moment it's made to its disposal. It also covers underground storage tanks.
- Environmental lien
- An environmental lien is a charge recorded against a property to recover the government's cost of cleaning it up. It stays with the land when it's sold.
Check the flood zone for an address, free
Enter any US address to see its FEMA flood zone and a map of the flood areas around it. Add your email to see which buildings sit in the flood zone and the risk numbers.