The environmental, safety, economic and legal concern resulting from
underground storage tanks has raised increasing concerns of both
underground and aboveground fuel oil storage tanks for home owners,
home buyers, lenders and real estate agents. Environmental issues
include soil and groundwater contamination. Some leaking tanks have
affected multiple families and entire communities. Potential fire risk
and tank collapse are safety concerns. Economic issues include:
maintenance costs, cost of tank system or soil testing, tank removal,
and potential contamination cleanup. Legal concerns include determining
responsibility and potential third party damages.
What Is The Law In Wisconsin?
All underground fuel oil and gasoline tanks, and aboveground tanks 110 gallon capacity and larger are
regulated by the SPS 310 administrative code.
The Wisconsin Administrative Code SPS 310 requires that all residential underground
tanks (UST) storing regulated product be registered with the Wisconsin
Department of Safety and Professional Services (DSPS). A registration form
must be completed and submitted to
the Department. The Department does not charge a fee for registration.
Heating fuel tanks located aboveground or in basements are not required
registered. Aboveground tanks for motor vehicle fueling are prohibited
at residential occupancies except for water-craft fueling (SPS
All underground gasoline or diesel fuel tank systems
(tank and piping) used to supply fuel for vehicle or other combustion
engines must be provided with corrosion protection and spill and
Tanks that are no longer in use must have closure. Closure is a term
for removal, although in specific situations the tank may be closed in
place. The closure of a UST must be supervised by a Certified
Remover/Cleaner and specific documents completed and submitted to the
Examples of signs that an underground tank may be located on your property at this link.
Residential aboveground and basement fuel oil storage
tanks are addressed toward the end of this page.
What If I Am Purchasing A Home That Has An
Underground Fuel Oil or Vehicle Fuel Tank?
Before purchasing a home it is strongly recommended that
buried tanks be tested. Once a property is purchased, the liability for
a leaking tank becomes the responsibility of the new owner. Testing for
a residential tank typically costs $300 to $500.
Tanks must be disclosed on the Wisconsin Realtors Association "Addendum A To the Offer To Purchase."
Upon completion of the purchase of the property the new owner must
initiate a change-of-ownership to the tank registration.
Gravity feed tanks for vehicle fueling are only allowed
under specific situations on farms; they are not allowed on residential
What If I Am Selling A Home That Has An Underground
Fuel Oil or Vehicle Fuel Tank?
Be honest and up-front about it. The Wisconsin Realtors Association Addendum
A To The Offer TO Purchase includes a disclosure statement.
Misrepresentation of the tanks status can result in significant legal
and liable consequences.
If the tank is not being used to provide heat to the furnace or provide
fuel to vehicles, the tank must have closure.
What Are The Signs That The Property May Still Have
A Buried Fuel Tank?
All tanks must have a fill pipe and a vent pipe. The fill pipe is
generally located directly above the tank. The vent pipe may be a
distance from the tank, but usually at a location near a building where
it can be supported as it is extended above grade. The copper tube fuel
supply line is connected to a fuel oil tank and may run through the
wall our under and up through the floor to the furnace. When
underground fuel tanks are closed, the closure was to be documented and
registered with the Wisconsin Department of Safety and Professional Services (DSPS).
Prior to 1988, USTs were allowed to be closed in place by filling with
an inert material. This practice is very restricted today and requires
specific regulatory approvals.
What Is The Likelihood That My Tank Is Leaking?
This is a difficult question to answer, especially with the wide range
of soil conditions in Wisconsin. Fuel oil tanks appear to last longer
than tanks storing gasoline. While not a scientific statistic, our
experience indicates that gasoline tanks begin failing at 12 to17 years
Most of the underground fuel tanks we deal with today
were installed in the past, under old technology and a much less
installation and environmental conscience. Leaks can be due to damage
at time of installation, improper installation, corrosive soils, or
tank and piping defects or damage. Many of the tanks are not designed
for use underground and were installed by untrained people. Present day
concerns were never anticipated when the equipment was installed. Tanks
were placed in beds of cinders, ashes, or cause outside-in corrosion
and leaks. Tanks may also be damaged by being dropped or pushed into
the excavated hole rather than being carefully lowered by a rope. Tanks
installed today must have a corrosion resistant exterior and components
that resist corrosion and the effects of pressure, vibration and
Moisture in oil joins with sulfur and other components
in oil to become acidic and corrosive. It encourages tank failure by
enhancing corrosive action from the inside. Water enters the fuel oil
tank from: a poorly sealed fill box which is flush with the ground or
which is located below a roof edge, from a missing fill pipe or vent
pipe caps, from loose pipe fittings, and less commonly, from water
delivered with fuel from an improperly maintained bulk storage
facility. Water can also leak into a tank from ground water if the tank
wall is damaged.
Underground fuel storage tanks usually fail from rust perforation due
to the effects of moisture inside the tank. In the case of heating oil,
the combination of water with sulfur in the fuel, bacterial action, and
other non compatibility factors. Buried tanks should be tested for the
amount of water present in tank bottom, and the water should be pumped
out. Water corrodes the tank which then leads to leaks. If the tank is
to remain in use, ask your fuel supplier about using an additive or
other methods to help remove water.
What Is The Proper UST Closure Procedure?
A proper abandonment procedure involves pumping out any remaining fuel,
cleaning the interior of sludge or residue, removing the tank, and
confirming that there has been no leakage. The closure procedure must
be supervised by an individual who is a Certified Remover/Cleaner. The
fill and vent pipes and supply line must be completely removed from the
tank and building to prevent mistaken delivery and spill into the
The Wisconsin Department of Natural Resources has classified the sludge
and waste accumulated during a residential tank closure as
"residential" waste, that may be disposed of via the traditional
residential waste disposal resources.
Closure-in-place is restricted to situations where the closure activity
may impinge upon the structural integrity of a building or mature
trees. The owner or owner's agent must request authorization to
close-in-place, providing the details why removal is a risk.
Closure-in-place is not an option to prevent digging through a driveway
or destroying shrubs and bushes. Closure-in-place requires that the
tank be cleaned and filled with an approved inert material.
Closure-in-place is frequently more expensive than removal.
Link to Closure
of Underground Storage Tank Technical and Administrative Guidance
How Do I Know If My Tank Is Registered?
The Wisconsin Department of Safety and Professional Services (DSPS) maintains the state storage tank database.
You may access this database on the Internet via: http://www.commerce.state.wi.us/ER-EN-tanks-search.htm.
If the tank is not registered you may print the form located at URL:
and complete and mail the form to the Department.
How Do I Have My Tank Tightness Tested?
Specialty companies and some oil companies have equipment to test
buried tanks for leaks (tightness testing). Both simple
pressure-testing and very sophisticated electronic testing are commonly
used, mostly on commercial tanks rather than residential tanks.
Tank testing methods vary in cost, invasiveness, length of time to
complete, and more. Contact a local fuel oil provider to inquire who
may be a reliable tightness testing contractor in your area or use the
second box search application for a Tank System Tightness Tester at the
Tank Contractor Search Application.
Testing for water in the tank is simple and can be done by any
petroleum equipment service person.
Residential Aboveground And Basement Fuel Oil
Aboveground tanks are tanks that are located: above ground, in vaults
void of earth, or in buildings. Typically, an aboveground heating fuel
storage tank at a residence is a 275 gallon oval shaped tank.
Aboveground tanks at 1 or 2 family dwellings must be installed under
the code's technical requirements. However, they are excluded from plan
review and certified installer requirements. All residential aboveground
heating fuel storage tanks that are connected directly to a heating
device are excluded from tank registration.
most frequent inquiry that we deal with relates to the heating oil
storage tank located in a basement. The SPS 310 code language is
written with a focus on larger aboveground storage tank located
outside. However, the environmental and fire safety spirit of the code
applies to all tanks. The code adopts NFPA 31, Standard for
the Installation or Oil-Burning Equipment (this standard
includes fuel storage tanks) and requires that aboveground tanks that
are not in use be rendered vapor free, closed by cleaning and removed
from the site.
Section 7.10 of NFPA 31, Standard for the Installation
of Oil-Burning Equipment, requires the fuel oil tank and any related
piping to be disconnected, emptied of contents, cleaned, and then
removed from the premises and disposed of in accordance with local
regulations.This includes removal of the outside fill and vent lines.
There have been isolated instances where the tank and
inside piping were properly removed, but the outside piping left in
place, and a fuel oil delivery subsequently made. This has resulted in
costly clean-up of the spill and, on rare occasions, a fire.
The closure of aboveground heating fuel tanks located at
a 1 or 2 family residence does not have to be
performed by an SPS 310 certified remover/cleaner (SPS 310.36 (3)(a)
2). A heating oil storage tank that is placed out of service
for any reason other than immediate repair or replacement shall follow
1.) The tank and all connected piping, including the vent and fill
piping, shall be purged of vapors, emptied and cleaned.
a.) Until the tank is removed, the tank vent shall remain intact and
b.) Until the tank is removed, the fill pipe shall be filled with
concrete to the top of the pipe and capped.
c.) Any piping that is not removed, other than a tank vent, shall be
capped or otherwise sealed.
d.) When the tank is removed all vent and fill piping shall be removed
from the premises
2.) Responsible parties. (a) Contractors. A person who is under
contract, with the person who owns or controls a property, to remove a
heating oil storage tank or to place a heating oil storage tank out of
service shall be responsible for complying with the requirements under
(b) Owners. If there is no contractor, the person who owns or controls
a property from which a heating oil storage tank is removed, or on
which a heating oil storage tank is placed out of service, shall be
responsible for complying with the requirements under (1).
3.) Notification requirement. The person who owns or controls property
from which a heating oil storage tank has been removed, or on which a
heating oil storage tank has been placed out of service, shall provide
written notice to the current heating oil vendor within 7 days after
removing the tank or placing the tank out of service. If there is a
scheduled delivery in less than 7 days, notification may be given
verbally provided it is followed by written notification within 7 days
after verbal notification.
removing fuel oil tanks in basements or aboveground on residential
property do not have to be certified; however, some of these
individuals have little training in the process as a certified tank
remover would have. In either situation as the property owner you
should ask the contractor to demonstrate that he has liability
insurance that covers tank closure activities.
In outside aboveground tanks water often enters the fuel oil tank from
condensation as temperatures change, particularly when the tank is not
kept filled. Tanks not properly managed may experience internal
corrosion while the exterior appears to be in good condition.
Firms that remove residential heating fuel tanks that are aboveground or in basements at this link
Do Home Inspections Include Storage Tank Assessment?
Generally, a comprehensive storage tank system assessment is not
conducted during a home or building inspection unless specific tank
system inspection arrangements have been made. Tank inspection, other
than casual visual inspection, tank tests, or removal require that you
use an appropriate expert.
Here are a few very basic things any home inspector can include when
the tank is visible and accessible:
-Is the tank exterior sound, without leaking seams or excessive rust?
-Is there a patch of dead vegetation under or around the tank or
components or other evidence of a history of leaking?
-Is the tank piping tight, leak-free, and does it drain freely into the
-Has the vent pipe been equipped with a whistle to signal the delivery
person when the tank is full?
-Are all tank plugs and piping tightly in place?
-Has black or galvanized iron piping been used for filler and vent
lines? Plastic or PVC lines are prohibited as they may come apart at
the seams during a tank filling activity. Some plastic lines can
shatter or break in extremely cold weather.
-Is the tank vented properly (1 1/2" - 2" diameter piping) to outside?
Improper venting can place excessive stress on tank seams and piping.
-Is the vent line properly capped with a screened weather-resistant cap
to prevent water entry or clogging by mud or insects?
-Is the vent next to the filler so that the delivery person can listen
to the event alarm and determine when the tank is full? The vent alarm
prevents over filling and is recommended for both underground and above
ground tanks. It should be mounted at the top of the tank at the vent
pipe opening. (Inspectors cannot see this component on buried tanks.)
-Is the fill gauge installed and tight? Loose gauges can cause spills
during tank fill operations.
-Are the tank support legs sound and on firm footing? A standard
275-gallon tank with an average capacity of 260 gallons weighs about
2000 lbs. Placed on wood or dirt the tank is likely to tip and spill.
-Has the tank been kept relatively full in spring and fall? The extra
weight helps prevent tank shifting and related piping leaks, and will
reduce water in the fuel (can cause loss of heat) from condensation.
Delivery driver responsibilities
(1) Prior to
delivery, the operator of the product delivery equipment that is transferring
the product shall ensure that the volume available in the tank is greater than
the volume of product to be transferred to the tank.
(2) The transfer operation shall be monitored constantly by the operator of
the delivery equipment so as to prevent overfilling and spilling.
Link to Health and Family Services Bulletins.
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