General Glossary

This equipment is installed on pressurized piping lines. Line
leak detectors (LLDs) must be able to detect large leaks of three
(3) gallons per hour (gph). Mechanical line leak detectors are
installed at the submersible pump head and usually work by
restricting the flow of product. Electronic line leak detectors
can be installed either at the pump head or at the dispenser and
work by detecting pressure increases or decreases that may
indicate leaks. Some electronic units are capable of performing

Also called an ATG, this is a permanent system installed in a
tank with probes that can provide tank leak testing and inventory
information. Some systems may also provide information like
product temperature, water levels, and ullage (amount of head
space in the tank).

This method involves sampling monthly for vapors that have been
released from product contained in the piping. The detection and
measurement of fumes using this method indicate a possible leak.
Also, there are a number of criteria that must be met to use this
as a leak detection option. If this method is used, it is
normally utilized for both the tank and the piping.

This is a method of leak detection than can only be used for
underground tanks that are 2,000 gallons or smaller. This method
requires monitoring on a weekly basis.

This is indicated if the tank is using SIR for leak detection.
There is not separate reporting for SIR piping leak detection.
The tank SIR serves as leak detection for both the tank and
piping.

This method involves taking daily measurements of tank contents,
deliveries, and sales. These figures are sent to a SIR vendor (a
third party) for statistical analysis that checks if the tank
system is leaking.

This indicates the type of site. It could be a tank site (TS),
leak site (LS), spill site (SS), composting facility (CF),
thermal processor (TP), land treatment facility (LTF) or a
non-tank Voluntary Petroleum Investigation and Cleanup (VPIC)
site.

This means that the tank has no overfill protection.

This device is installed at the connection of the vent pipe to
the tank. It extends into the tank and should be set at the 90
percent full level. Ball float valves work via a ball inside a
wire cage that floats up with the rising product level which
blocks off the vent line. When this occurs the delivery person
is alerted to shut down the delivery.

This is a method of external leak detection that involves the use
of one or more monitoring wells placed close to the UST that can
be monitored visually or by electronic sensors. The wells are
checked monthly for the presence of product that has leaked from
the UST and is floating on to the groundwater. If this method is
used, it is normally used for both the tank and the piping.
Also, there are a number of criteria that must be met to use this
as a leak detection option.