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
- In a basement or crawlspace, with a separate exterior access
- In a basement or crawlspace, with access through the home only
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.
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.
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