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.

Washington Department of Ecology

State of Washington Department of Ecology

The Washington Department of Ecology does not regulate the use or operation of residential heating oil tanks, like the State of Oregon does. However, some local governments may have different requirements or guidelines that may apply to residential storage tanks. Regulations and policies vary from place to place and may change from time to time.

Are there specific concerns I should have as a homeowner if I have an abandoned oil tank on my property?

  • Tanks can develop holes and release heating oil into the soil. The released oil can contaminate groundwater, surface water, storm sewers, and cause vapor problems in nearby buildings. Under the state Model Toxics Control Act, the tank owner may be held liable for damage caused by a leaking tank.
  • Corrosion can cause underground tanks to deteriorate, making cave-ins a possibility. The homeowner could be held liable for injuries caused by a cave-in.
  • Before finalizing the sale of a house, lending institutions and home buyers may want sellers to remove or “close” unused heating oil tanks. To “close” a heating oil tank, the homeowner has the tank cleaned out and filled. The tank is then left buried in the ground.
Washington Department of Ecology

Washington Department of Ecology – tank found within a backyard in Vancouver, vent pipe can be found running along the side of the house to the left of the window. The sampling of this tank resulted in a Risk Based Clean-Up.

How does Ecology prefer decommissioning take place?

Ecology recommends that the tank is removed with proper soil samples taken, and remediation, if necessary. However, decommissioning the tank in-place is also acceptable, as long as soil samples take place and remediation is completed, if necessary.

Can I decommission my tank as a homeowner?

There is no law prohibiting homeowners from doing their own decommissioning. Although, Ecology does not recommend doing the tank work yourself because of the potential safety risks. Hiring an experienced contractor is advised, as working on an underground storage tank can be dangerous. Under certain conditions, tanks can explode. Working in the excavation pit, cutting open or handling heavy tanks, and using power equipment also pose risks to the homeowner. Ecology recommends that homeowners hire an experienced contractor to perform decommissioning work.

Leaking tanks and the State of Washington Department of Ecology

What if a tank has leaked?

Knowingly using a leaking tank is negligence. If you discover that your tank is leaking you must take immediate action to stop the leak. In most cases where a tank has leaked, only the soil near the tank is affected. Sometimes, however, the heating oil may also have contaminated groundwater or surface water. It is the homeowners or contractors responsibility to:

  • Evaluate the extent of contamination caused by the leak
  • Evaluate the extent of the contamination caused by the leak
  • Determine if it is a threat to human health and the environment
  • Clean-up any contamination caused by the leak

Should I report the leak to Ecology?

Minor Leaks or Spills that affect only the soil near the residential heating oil tank do not have to reported to the Department of Ecology.   However, if the minor leak was discovered during the process of the tank being decommissioned, Ecology does recommend reporting the minor spill through the ERTS program.

Contaminated Soil above 2000 PPM does need to be reported to the Department of Ecology. Any groundwater, surface water, free product or vapor intrusion should also be noted during the reporting process.

How do I report a leak to Ecology?

All confirmed releases must be reported to the Washington Department of Ecology within 24 hours to the ERTS SYSTEM. A leak can be reported via a phone call or through the online reporting system.

Should I clean-up contamination?

Absolutely, and the Department of Ecology recommends that homeowners hire a qualified clean-up contractor to perform the remediation. When the clean-up has been completed, the contractor should give the homeowner a copy of the clean-up report. Clean-up reports of minor leaks do not need to be sent to Ecology, as they do not track or report on these clean-ups. Clean-up reports on more extensive leaks do need to be sent to the Ecology regional office, as they do keep track of and report on these sites. All reports should be kept by the homeowner for their records and the remaining life of the property.

Does the Department of Ecology have a LUST list like the State of Oregon?

Yes, it is called the Confirmed and Suspected Contaminated Site List (CSCSL). However, the majority of the sites on this list are large properties, with larger leaks (i.e. gas stations). It is extremely rare when a residential property does appear on this list, reasons that a site would appear on CSCSL is as follows:

  • When a property has been reported, but after 90 days, no closure and/or continued work to complete the remediation has taken place.
  • If groundwater has been encountered, the property automatically gets put on the CSCSL. The homeowner/contractor then has to go through the voluntary clean-up to get taken off the list. Ecology then works with the homeowner/contractor to get off the list by providing opinions on the work being completed and to verify if meets the status of no further action.

Additional Website Links:

Generic Remedy Clean-Up

Generic Remedy Clean-Up

A Generic Remedy Clean-Up is considered a mid-level contamination, consisting of a release of 501 – 10,000 PPM. This remediation is a soil-only clean-up as long as there is no impact to groundwater, no free product is present and there is no vapor intrusion into the home or building. A generic remedy may require soil removal, as well as additional soil samples around the tank to determine the extent of the contamination. Total Petroleum Hydrocarbon (TPH) concentrations up to, but not exceeding, 10,000 PPM of soil may be left in place if:

  • There is at least three feet of clean soil over the contaminated soil
  • The volume of remaining contaminated soil (over 500 PPM) does not exceed 65 cubic yards
  • Analysis for the presence of benzene, ethylbenzene and naphthalene must be performed on all samples exceeding 2,500 PPM.
Generic Remedy Clean-Up

Generic Remedy Clean-Up – this is the fill cap from a tank that was decommissioned through a generic remedy remediation. The concrete was cut in order to gain access to the tank underneath the concrete patio.

Generic Remedy Clean-Up

Generic Remedy Clean-Up – Fill material from a tank that was being decommission through generic remedy remediation, this tank was found to have leaked at 5710 PPM

Once the investigation of the soils around the tank and the contaminated soil has been removed, the generic remedy clean-up decommissioning of the tank can continue.

In order to establish if a generic remedy is necessary, the DEQ requires a site assessment must be conducted to determine the source, nature, magnitude and extent of the contamination associated with a release from the underground storage tank. The site assessment must specifically address:

Generic Remedy Clean-Up Investigation

  • Determine the presence of free product
    • If there is pooling of liquid fuel in the tank excavation area or if there is clearly visible saturated soil, free product is present and a generic remedy remediation is no longer acceptable.
  • Determine if groundwater is affected and the depth to groundwater
    • During the tank excavation, if groundwater impact is discovered, the DEQ requires the water be pumped from the pit. If the pit remains dry for 24 hours, sampling and clean-up may proceed under the generic remedy. If water returns in less than 24 hours, it is presumed to be groundwater and the use of the generic remedy remediation is not allowed.
  • Determine the vertical and horizontal extent of the heating oil contamination
    • If decommissioning will be performed by removing the tank, two samples must be taken from each end of the excavation, at least 6 inches below the bottom of the excavation. If, by visual observations, additional contamination or odors are detected, samples must be collected from these areas as well.
    • If the decommissioned tank is to stay within the ground, two soil samples are to be taken from each end of the tank, as well as one below the tank bottom. The samples are to be taken no more than six inches from the tank end and at least one foot below the tank bottom. If contamination or odors are encountered, based on visual observations, samples must also be collected from these areas as well.
    • An estimated volume of contaminated soil proposed to remain at the site will be required to ensure that the 65 cubic yard limitation is not exceeded. Results of soil samples analyzed for the presence of heating oil are required to determine both the vertical and horizontal extent of contamination remaining above 500 PPM.

We have provided a link, this provides more insight to understanding more of the DEQs requirements regarding Generic Remedy Clean-Up remediation standards and guidelines.

Important EcoTech Documents

For additional information regarding our service lines, we have attached supplementary documents for your reference.

Heating Oil Tanks

Radon Mitigation

Seismic Retrofits

Septic Tanks & Cesspools

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.