Above Ground Storage Tank or AST

Above Ground Storage Tank or AST Common Questions

 

Above Ground Storage Tank or AST, like an Underground Storage Tank (UST), contain heating oil for the purpose of heating homes and buildings. There are specific differences between the two tanks and these are some of the most common questions we are asked regarding ASTs.

What is an above ground storage tank or AST?

Homes, apartments, farms and some businesses that are currently or were heated using diesel heating oil, used an above ground storage tank (AST) to store the heating oil. ASTs are most commonly mounted on a stand or a ground pad either outside or in a basement. ASTs can also be partially buried in the ground, usually in a basement or crawlspace.

Since it isn’t underground, do I really need to be worried about an AST?

Yes, even above ground tanks can leak, resulting in contamination of soil and drinking water supplies. Any oil spill can pose a serious threat to human health and the environment, regardless of where the tank is located.

What is the difference between an AST and a UST?

The distinct difference between the two tanks is this:

  • If the tank and its piping is located 10% BELOW ground surface it is considered a UST, anything ABOVE 10% ground surface is considered an AST.
  • Another exception is that, ASTs are not regulated by the DEQ, therefore not governed the same way as a UST.

For example, if a UST is leaking above 50 PPM (parts per million) the contractor is required to report this to the DEQ and is subject to remediation, based on the level of contamination. After the clean-up has been completed, the UST is then decommissioned and registered with the DEQ. This scenario can also be compared for an out of service underground storage tank, once the tank has been decommissioned it can then be registered with the DEQ.

The circumstances for an AST are different. When an AST is or has leaked, is no longer in-service, or the homeowner is switching to a new heat source, the tank can simply be removed, no decommissioning or registration with the DEQ is required. However, like decommissioning an underground storage tank, each AST removal can bring about a different set of considerations.

What to do with an Above Ground Storage Tank AST when decommissioning is not an option

If you don’t decommission and register the AST with the DEQ, what do you do?

First, we would need to determine where is the tank located?

  • Outside the home
Above Ground Storage Tank or AST

Above Ground Storage Tank or AST – Exterior AST secured to concrete pad foundation.

  • In a basement or crawlspace, with a separate exterior access
Above Ground Storage Tank or AST

Above Ground Storage Tank or AST – AST located in basement with exterior access.

  • In a basement or crawlspace, with access through the home only
Above Ground Storage Tank or AST

Above Ground Storage Tank or AST – AST located within a crawlspace, no exterior access. For this AST to be removed, it will need to be cut into pieces.

Regardless of where the above ground storage tank or AST is located on your property, it is very important to have it removed by a licensed contractor with pollution insurance. If the AST is removed by a general contractor, and they usually DO NOT have pollution insurance, and heating oil is spilled in the house or the yard, the homeowner will be left with the clean-up, not the contractor.

Once the location has been determined:

  • All heating oil and sludge are pumped out, the tank removed and disposed of via recycling.
  • Depending if the tank is on the exterior or interior of the home determines if the tank can be removed as one piece or if it will need to be cut into portions and carried out of the home.
  • If applicable, the fill and vent are removed and holes would be patched.
    • Removing or concreting over the fill eliminates the possibility of an accidental fuel re-fill.
Above Ground Storage Tank or AST

Above Ground Storage Tank or AST – AST Vent (the larger pipe) and fill pipe.

When an Above Ground Storage Tank (AST) Leaks

What would cause an AST leak?

There are numerous reasons an AST can leak; improperly secured tanks, tank corrosion, equipment or support failure, overfilling the tank, or it could be as simple as human error.

Above Ground Storage Tank or AST

Above Ground Storage Tank or AST – Tank that has fallen down, if the contents are not pumped out, diesel fuel would be leaked into the yard.

My AST is leaking, what should I do?

  • Place a bucket underneath the tank to catch the release
    • If the AST is within the home, block all floor drains to prevent discharge into a drywell or sewer
  • Call a qualified heating oil tank provider that can respond to and clean-up a leaking tank
    • The AST would be pumped of all residual liquids
    • Clean-up would be performed to remove any heating oil contamination
Above Ground Storage Tank or AST

Above Ground Storage Tank or AST – Leaking AST, small bowl has been placed underneath the leak to catch the heating oil.

UST Tank Search for Sellers

UST Tank Search for Sellers – Common Questions

As a homeowner, you may be thinking about or are preparing to put your home up for sale. For some homeowners, you may want to perform a tank search to prepare yourself for any unforeseen surprises during the home inspection period. On the other hand, you may know that there is a tank on your property that was decommissioned and never registered with the DEQ or that there is an abandoned oil tank, but you don’t know where. These are some of the most common questions that we are asked regarding the tank inspection process and important information you should know before you sell.

What is an underground storage tank (UST)?

Homes, apartments, farms and some businesses that are currently or were previously heated using diesel heating oil, used an underground storage tank (UST) to store the heating oil. The USTs were usually buried in the yard, and copper tubing or steel piping was installed to deliver the diesel from the tank to the furnace. In Oregon, an estimated 100,000 USTs were installed for home heating.

UST Tank Search for Sellers

UST Tank Search for Sellers – Rendition of an underground storage tank (UST) buried in a yard, with the supply lines running into the home.

Why should I worry about an UST?

Underground storage tanks are made of steel, which are selected for their strength, not for their corrosion resistance. Therefore steel USTs rust through, given enough time. Like a roof, steel storage tanks have a life of about 25 years, and like a roof it is cheaper to replace the tank or convert to another heat source before it leaks and the damage is done.

UST Tank Search for Sellers

UST Tank Search for Sellers – Shot from interior of tank, many small holes in the UST, which will cause diesel fuel to leak into the surrounding soil.

Performing the UST tank search

How do you find an abandoned UST?

The best way to determine if there is an abandoned oil tank on the property, is to conduct a tank search. As the homeowner, you may also look for these tell-tale signs of an abandoned oil tank:

  • An Oil Fill Pipe, these are usually close to the ground and near where the furnace is located in your home.  The lid itself will usually indicate OIL in the center of the cap.
UST Tank Search for Sellers

UST Tank Search for Sellers – Fill pipes can appear in multiple places within a property, in a walkway, grass, driveway, and even under a deck are a few examples.

  • A Vent Pipe, this is usually attached to the home, about two to eight feet up the side of the house and it is 1.25 to 1.5 inches in diameter with a small vent cap on it.

 

UST Tank Search for Sellers

UST Tank Search for Sellers – 4 different types of vents and their locations.  Fill vents can come in different sizes, colors, and may be placed at varying sections of the home.

  • Product lines, may be found sticking out of the ground in the yard, in a crawlspace or basement floor.  Product lines may still be attached to a basement or crawlspace wall next to water or gas pipes.
UST Tank Search for Sellers

UST Tank Search for Sellers – Crimped product lines may appear as random pipes sticking out of a basement floor or out of the dirt near the home in the yard. A product line may also appear running up a wall in a basement or crawlspace, like the far right picture (the thin line on the right)

  • Patching, will be present on a basement floor, it appears as though a pipe has been removed and covered with concrete.  The patching may appear as a bad “patch job” with numerous bumps and grooves.
UST Tank Search for Sellers

UST Tank Search for Sellers – Patching on a basement floor.

How do you perform a tank search?

EcoTech first will perform a Tank Background Search, this entails a detailed examination of state and local databases, as applicable. Besides years of on-the-job experience, our technician conducts a visual inspection for product lines and fill or vent pipes, utilizes metal detectors and Terra, our specially trained Petroleum Detection K-9.

UST Tank Search for Sellers

UST Tank Search for Sellers – Terra finds a tank within a planter.

UST Tank Search for Sellers

UST Tank Search for Sellers – The tank that Terra found is marked out. The purple arrow indicates where the vent pipe has been removed from the siding. The red arrows indicate the length of the tank, marked with orange flags as well as the tip of the measuring tape.