Managing Underground Storage Tanks in the United States
Claudia J. Gutierrez, Research Scientist, US Environmental Protection Agency, Region II
Jack Caravanos, DrPH, Assistant Professor, Hunter College CUNY
I. INTRODUCTION
Over one million underground storage tank systems (USTs) in the United States contain
petroleum or hazardous substances regulated by the United States Environmental Protection
Agency (EPA). Many of these underground storage tanks have leaked. This paper seeks to
briefly describe the obligations tank owners have in managing underground petroleum
storage tanks.
Releases from USTs arising from spills, overfills or leaking tanks and piping can cause fires
or explosions that threaten human safety. Releases can also pose a significant health threat
by contaminating the groundwater that many of us depend on for the water we drink. Properly
managed, USTs will not threaten our health and the environment. This is a problem
worldwide since releases from underground storage tanks can threaten human health and
safety. UST releases can also contaminate soil and drinking water supplies. More than
287,000 UST releases have been confirmed in the US, EPA estimates half that about of these
releases reached groundwater.
Federal legislation, directed EPA to develop the underground storage tank regulations which
requires owners and operators to:
 prevent releases from USTs,
 detect releases from USTs, and
 correct the problems created by releases from USTs.
US EPA defines an underground storage tank as a tank and any underground piping
connected to the tank that has at least 10 percent of its combined volume underground. The
federal regulations apply only to USTs storing either petroleum or certain hazardous
substances and not food or other non-hazardous materials.
II. FEDERAL REGULATIONS
Release Detection Monitoring Methods
The US Environmental Protection Agency has research release detection monitoring methods
and has mandated owners adopt a program to detect leaks. The technologies are briefly
described below.

Interstial Monitoring: This method detects leaks in the space between the UST and a
second barrier. The regulations describe general performance requirements for
interstial monitoring with double-walled USTs, USTs fitted with internal liners and
Managing Underground Storage Tanks in the United States 1
USTs using interception barriers.

Automatic Tank Gauging Systems: This method uses automated processes to monitor
product level and inventory control.

Groundwater Monitoring: This method monitors the groundwater table near an UST
for the presence of released free product on the water table. Monitoring wells near the
UST are checked frequently to see if petroleum can be detected. However, this
method cannot be used if the water table is more than 20 feet below the surface of the
ground.

Soil Vapor Monitoring: This method samples vapors in the soil gas surrounding the
UST. Leaked petroleum produces vapors that can be detected in the soil gas.
However, this method requires using porous soils in the backfill and locating
monitoring devices in these porous soils near the UST system.

Statistical Inventory Reconciliation: This method uses sophisticated computer
software to conduct a statistical analysis of inventory, delivery and dispensing data,
which you must supply regularly.
Instead of using one of the monthly monitoring methods noted above you can combine
inventory control and tank tightness testing, but only for 10 years after you install a new UST.
Inventory control involves taking daily measurements of tank contents and recording
deliveries and amount pumped. Tank Tightness Testing requires taking the UST out of
service while changes in level or volume are measured over time.
Spill Protection
USTs must have catchment basins to contain spills. Catchment basins are also called spill
containment manholes or spill buckets. Basically, a catchment basin is a bucket sealed
around the fill pipe. To protect against spills, the basin should be large enough to contain
what may spill when the delivery hose is uncoupled from the fill pipe.
Overfill Protection
USTs must have overfill protection when they are installed. The three main types of overfill
protection devices are:
1.
Automatic shutoff devices: An automatic shutoff device installed in an UST’s
fill pipe can slow down and then stop the delivery when the product has
reached a certain level in the tank.
2.
Overfill alarms: Overfill alarms use probes installed in the tank to activate
alarm when the tank is either 90 percent full or within 1 minute of being
overfilled. The alarm provides the driver to close the truck’s shutoff valve
before an overfill happens.
3.
Ball float valves: Ball float valves are placed at the bottom of the vent line
Managing Underground Storage Tanks in the United States 2
several inches below the top of the UST. The ball floats on the product rises
with product level during delivery until it restricts vapor flowing out the vent
line before the tank is full. If all tank fittings are tight, the ball float valve can
create enough back pressure to restrict product flow into the tank which
notifies the driver to close the truck’s shutoff valve.
Corrosion Protection
Tank and piping completely made of noncorrodible material such as fiberglass. Also,
provided if tank and piping are completely isolated from contact with the surrounding soil by
being enclosed in or jacketed in noncorrodible material
Tank and piping made of steel having a corrosion-resistant coating and having cathodic
protection. A corrosion-resistant coating electrically isolates the coated metal from the
surrounding environment to help protect against corrosion. Tank made of steel clad with a
thick layer of noncorrodible material.
III. USING A DATABASE TO BETTER MANAGE THE UST WORLD
US EPA has delegated the registration and data management of New York States
underground storage tanks to the Department of Environmental Conservation. This database
keeps track of all USTs in New York State and the spills occurring from releases of product
in New York State and is used by federal EPA offices in evaluating and ensuring compliance
with federal regulations. However, USTs in New York State are only required to register
tanks whose capacity is over 1,100 gallons.
Petroleum Bulk Storage Database
This database requires owners and operators to register their tanks with New York State. The
facility must have a total capacity of 1,100 gallons or more to be regulated. The following
must be submitted in order for the registration to be approved:
 Name, location and phone number of the facility;
 Name of operator of the facility;
 Name and address of owner of the facility;
 Type of petroleum facility such as: storage terminal/petroleum distributor, retail
gasoline sales, other retail sales, manufacturing, utility, trucking /transportation,
apartment building, school, farm, airline, private residence, etc.
 Tank number
 Tank location
 Status
 Installation date
 Capacity
 Product stored
 Tank Type, Tank Internal and External Protection
 Piping type, internal and external protection
 Secondary containment
Managing Underground Storage Tanks in the United States 3




Release detection
Spill/Overfill protection
Type of dispenser
Certification that all documentation submitted is true and correct. False statements
are punishable by Law.
Spill Database
Any person with knowledge of a spill, leak or discharge of petroleum must report the incident
to the New York State within 2 hours of discovery. Also, the results of any inventory record,
test or inspection that shows a facility is leaking must be reported. This database has all the
information of the spills reported to the New York State. The following information must be
submitted when calling to report a spill approved:
 Name of facility
 Name of caller, address and phone number
 Date of Spill
 Time of Spill
 Material Spilled
 Amount Spilled
 Amount Recovered
 Spill caused
 Resource affected
 Spill Source
 Remarks
 Registration information
IV. CONCLUSION
Releases are bound to happen if you own and or operate a UST system, but they can be
minimized if you do proper management of the tanks. Warning signals indicate that your
UST may be leaking and creating problems for the environment and your business. You can
minimize these problems by paying careful attention to early warning signals and reacting to
them quickly before major problems develop.
Proper management is the key to avoiding any releases into the environment. However, if a
release is suspected, you must respond quickly to any evidence of released petroleum that
appears at your facility. Report it immediately to the appropriate agencies this way public
health and the environment are not jeopardized.
Managing Underground Storage Tanks in the United States 4