A tank that happens to be underground.
An Underground Storage Tank (UST), in United States environmental law, is a tank and any underground piping connected to the tank that has at least 90 percent of its combined volume underground. ==Tank types== Underground storage tanks generally fall into four different types: ==Petroleum underground storage tanks== USTs, used to store petroleum, ...
For purposes of Subtitle I of the Resource Conservation and Recovery Act, this is any tank used to s