What is an 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.
In more detail
Federal UST rules (40 CFR Part 280) took effect in 1988 and set leak detection, corrosion protection and spill rules, with upgrade deadlines in 1998. States run most programs and keep registration records.
Some tanks are exempt from federal rules, including farm and residential tanks of 1,100 gallons or less holding motor fuel for noncommercial use, and heating oil tanks used on the premises. Exempt tanks often don't appear on any list.
Tanks that are closed are either removed or filled in place. Abandoned tanks that were never closed are a common surprise.
What it means when you buy
Ask for the tank history at any property that ever sold fuel, repaired vehicles, ran a generator or heated with oil. A tank you don't know about is a tank you can't price.
How the pre-screen handles it
The pre-screen checks state tank registrations and EPA's tank data for the site and neighbors, and looks in historical aerials for fuel islands and tank pads.
Pre-screen a property before you spend on a Phase I
A desk review of one address: past uses from historical photos and maps, federal and state environmental records, and flood risk, ready usually within the hour. $100 for one report, or $100/month for 3.