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:

PLIA in Washington State

PLIA Insurance Coverage

In 1995 the Washington Legislature added pollution liability coverage for heating oil tanks to PLIAs responsibilities. PLIA in Washington State assists owners of underground storage tanks to provide available and affordable insurance through a state administered reinsurance program. The program was created in response to the rising number of heating oil tank releases and the significant impact contamination had on property values, as well as the environment. When a clean-up has been completed, PLIA will provide homeowners with a Letter of Finding which states that the site has met the clean-up standards defined in the Model Toxics Control Act.

PLIA can also assist homeowners with the following information:

  • Verifying the validity of required declarations of financial responsibility
  • Provide advice and technical assistance regarding liability and clean-up requirements

What is covered when insured through PLIA?

  • Up to $60,000 to clean-up contamination, not covered by other insurance, on your property and/or a neighboring property
  • The contamination must come from a leak that starts after a heating oil tank is registered with PLIA. The tank may be a UST or an AST
  • The tank must be registered in the current owners name
  • Reimbursement up to $1500 to repair damages on neighboring property (third party coverage) such as landscaping, flooring, painting, etc.

What is NOT covered through PLIA?

  • Leaks from abandoned or previously decommissioned tanks
  • Leaks that start before registering with PLIA
  • Property restoration on your property (first party coverage)
  • Removal/repair/replacement of the tank/lines/furnace
  • Emergency heat restoration
  • Heating oil lost in the release

How do you apply for insurance through PLIA?

  • No cost to register
  • Must complete and submit to PLIA the PLIA registration form
  • You must be registered with PLIA prior to the start of any accidental release in order for the clean-up to be covered
  • When PLIA receives the completed registration form, you will be mailed a confirmation. If confirmation is not received within 14 days, contact PLIA at 1-800-822-3905 or 360-407-0520

How to file a claim through PLIA

  • If a release is suspected or confirmed from your registered heating oil tank, PLIA must be contacted at 1-800-822-3905 or 360-407-0520 within 30 calendar days from the date the tank is disconnected from the furnace.
  • PLIA will investigate the claim, which may include taking photos of your property and the failed tank
  • Owner will hire an approved contractor to do the clean-up
  • All work must be approved by PLIA before the work starts

Who is the Policy through?

  • The Pollution Liability Insurance is covered through The Colony Insurance Company, please click the link to read about the WA Pollution Liability Policy

PLIA Insurance Coverage and Soil Sampling

How to get started, obtaining soil samples through a site assessment

  • The heating oil tank owner must select a service provider to perform the site assessment and is responsible for payment of all costs associated with soil sampling.
  • PLIA will interpret and provide a report to the owner with the results of the soil testing. Each report will provide the following information:
    • No apparent contamination that poses a threat to human health and the environment, no further action is required.
    • Minor contamination is present at the site and further site assessment or clean-up may be required.
    • Serious contamination is present, appears to pose a threat to human health and the environment, immediate corrective action is required.

What are the costs associated with the insurance through PLIA?

  • PLIA in Washington State insurance coverage is required to collect from the tank owner, requesting technical assistance, the costs incurred in providing assistance.
  • Costs incurred may include travel costs and expenses associated with monitoring site assessments, review of reports and analyses and preparation of written opinions and conclusions.
  • The Technical Assistance cost is $350.00 and must be paid in full prior to PLIA issuing its report of review and assessment of data.

Additional PLIA informational websites:

Heating Oil Technical Assistance Program (HOTAP) through PLIA Insurance Coverage

If a tank owner DOES NOT have insurance through PLIA, and it is determined that their tank is leaking, is there anything that PLIA can assist with?

Yes, even if the leaking tank is not covered by the Heating Oil Insurance Program through PLIA, a homeowner can request assistance on tank removal and environmental clean-up under the Heating Oil Technical Assistance Program (HOTAP).

How can HOTAP help my uninsured leaking UST?

Through HOTAP, PLIA can provide advice and technical assistance to owners of active or abandoned heating oil tanks if contamination resulting from a release is suspect. Advice and assistance may include:

  • Review of clean-up plans and reports
  • Interpretation of results from soil sampling through a site assessment or site check
  • An opinion letter from PLIA to the owner regarding the results of the testing

How does HOTAP work?

  • The owner of the UST will perform soil sampling, through a site check or site assessment. The owner of the tank may chose a service provider of their choice to perform any and all site work at the property. The tank owner is responsible for payment of all costs associated with soil sampling, site assessment and remediation.
  • Once sampling has been completed, the results of all testing must be forwarded to PLIA for review and evaluation. A copy of the service provider’s field notes must also be forwarded to PLIA.
  • If testing and remediation has been completed prior to PLIAs review, PLIA will consider providing a review and evaluation of the data. PLIA considers how recently the testing and remediation was completed and will consider the methods of the assessment prior to agreeing to review and evaluate the results.
  • Upon completion of review and evaluation, PLIA will provide an opinion letter informing the owner of the review and assessment of the data. The opinion letter from PLIA will provide the following opinions:
    • Property Further Action Opinion Letter– further remedial action is necessary at the property to clean-up contamination and remediation action is also necessary elsewhere at the site
    • Property No Further Action Opinion Letter – no further remedial action is necessary at the property to clean-up contamination at the site and that further remedial action is still necessary elsewhere at the site
    • Site Further Action Opinion Letter – further remedial action is necessary to clean-up contamination at the site
    • Site No Further Action Opinion Letter – no further remedial action is necessary to clean-up contamination at the site

What is the cost for HOTAP?

The fee for the Heating Oil Technical Assistance Program is $350.00. This fee covers the cost incurred in providing advice and assistance, expenses, review of reports and analysis, and preparation of written opinions and conclusions. The fee must be paid in full prior to PLIA issuing its report of review and assessment of data.

As a homeowner, I’ve discovered my tank has leaked but I’m not registered with PLIA.  I can now register in the HOTAP program to receive a review of the testing results and a letter from PLIA “closing the site”?  This is at a cost of $350?  All other out-of-pocket expenses; sampling, remediation, etc. come out of my pocket?

Yes, to all three questions.

My leaking tank is not registered with PLIA and I opt NOT to join HOTAP, as long as I’ve registered with Ecology I’m fine, correct?

No, the site still needs to be addressed and remediation is required. If a homeowner would like a letter stating the site has been closed through PLIA, they would need to enter into the HOTAP program.

I’m selling my home and the buyer has performed a tank search, and a tank has been found. Can I now register the abandoned tank with PLIA?

No, abandoned tanks CANNOT be registered with PLIA  in Washington State. Only active tanks are eligible for the program.

Soil Sampling in Washington

Soil Sampling in Washington State

Like Oregon, in order to determine if a tank is currently or has previously leaked, an investigative process needs to take place through soil sampling. Again, showcasing the differences between the two states, soil sampling in Washington State separates this function into either a Site Check or a Site Assessment.

Additionally, when the initial soil sampling takes place, to determine if contamination is present, the State of Washington requires a minimum of three (3) samples be taken. One sample must be taken from each end of the tank and the third sample must be taken from the middle of one side of the tank. This is unlike OR, in that, the DEQ requires only two (2) samples be taken from each end of the tank. The three (3) soil sampling requirements are the same as when decommissioning an underground storage tank in place or by removal, as long as no obvious contamination is discovered.

Soil Sampling in Washington

Soil Sampling in Washington – three (3) soil samples are taken in a Washington UST. A sample must be taken from each end of the tank and one from either side of the tank in the middle.

Site Check is the investigation of an underground storage tank site for the presence of a release when evidence indicates that a release may have occurred, but existence of such a release has not been confirmed. Once the existence of a release has been confirmed, the release shall be reported to the State of Washington Department of Ecology.

Examples for a site check include:

  • Environmental contamination may be suspected and can include, but not limited to, constituents in soils, basement, groundwater and/or surface waters.
  • If environmental contamination is discovered off site and a UST is a suspected source of the release, the department may require a site check to confirm whether the UST system is the source of the release.

Site Assessment is an investigation to determine if a release has occurred: it may be required as part of a routine closure, change-in-service, and temporary closure extension, or as directed by the Department of Ecology.

  • For the purpose of a real estate transaction or to determine the state of an in-use or abandoned underground storage tank, a site assessment is conducted.
  • If an UST System is being decommissioned in-place or removed, a site assessment must be conducted after the UST system is emptied and cleaned and all liquid and accumulated sludge has been removed. While removed, a site assessment must be conducted following tank removal.
  • If a UST system was permanently closed or abandoned before December 22, 1988 and the department determines that suspected releases from the UST system may pose a current or potential threat to human health or the environment, the department may require a site assessment to be conducted. If an abandoned tank contains product, a site assessment is required.
  • Owner/operator applies to the department to extend a temporary closure of an UST system beyond 12 months, a site assessment must be completed before the application extension will be considered.

Leaking Soil Samples in Washington State

Contamination has been verified through soil sampling, within 24 hours the leak must be reported to the Department of Ecology. Department of Ecology reporting can either be completed through contacting the state directly or through their online system.  Once the contamination submission has been received by the State, an ERTS number will be given to the person who reported the leak. The ERTS number will also be forwarded to PLIA, as PLIA has an agreement with Ecology to evaluate the adequacy of any independent clean-up action performed by the requirements in the Model Toxics Control Act.

PLIA, can also provide homeowners the option of insuring their underground storage tanks before they leak, as well as helping after a leak has been discovered. Please see detailed information on our PLIA informational page.

Risk-Based Clean-Up

Risk-Based Clean-Up

Risk-Based remediation addresses the highest level of contamination from a leaking underground storage tank, with levels reported above 10,000 PPM. According to the DEQ, a risk-based clean-up offers the greatest amount of flexibility and adaptability to site-specific conditions. However, it is also the option that might require collecting additional site data and evaluation of more alternatives than a soil matrix or generic remedy clean-up. Risk-based clean-ups are the most rigorous option, with the collection of several soil samples to determine the magnitude and depth of contaminated soil, as well as how far the contamination has spread. The most important aspect of a risk-based clean-up is the evaluation of current and reasonably likely future risks to human health and the environment.

A risk-based remediation involves a soil investigation, which examines the pathways the contamination has likely spread. This pathway evaluation determines where the contaminants were released, how the contaminants can be transported to new locations and the reasonably likely ways that people may come into contact with them. Tests need to be conducted on enough samples to determine the lateral extent, as well as the depth of the petroleum contamination.

There are three investigative phases of concern while conducting a risk-based clean-up, phase two and three may not be necessary if the area of contaminated soil is limited enough in extent. Below are the steps, in order, that are required by the DEQ in order to close a risk-based clean-up:

Risk-Based Clean-Up and Free Product, Groundwater and Soil Vapor Gas

Petroleum Contaminated Soil (PCS) and/ or Free Product:

Up to seven (7) soil samples are taken to establish a representative sample and delineate the vertical and lateral extent of the pocket of petroleum-impacted soil, and potential or actual groundwater impacts. If it is determined that there is free product or large volumes of heavily contaminated soil, from which product may continue to migrate, mitigating the risk by excavation and off-site removal would be required, to the maximum extent practicable.

Risk-Based Clean-Up

Petroleum Contaminated Soil (PCS) seen during an excavation. The PCS is pictured here in the greyish color.

Risk-Based Clean-Up

The side view of the PCS, here you can see the coloration difference between the contaminated and the native soil.

Risk-Based Clean-Up

Free Product refilling into a sample boring hole

Risk-Based Clean-Up

Free Product within a sampling tube

Groundwater:

Has groundwater at the site at risk or has it been impacted by the diesel contamination?

In order to determine if groundwater has been or could be potentially encountered, a 10’ separation is required by the DEQ between the vertical extent of the contaminated soil and any potential shallow groundwater.

If there is no impact or potential impact to groundwater?

The groundwater investigation is now completed, no further action would be required.

If groundwater has been or has the potential to be impacted, what are the next steps?

A representative well will be installed in the source area to determine if groundwater has been impacted by the release. The installation of the representative well is designed to obtain a groundwater sample to measure, if any, the water level elevation in the contaminated water or soil.

If the samples in the representative well have detections that exceed the DEQs Ingestion and Inhalation from Tap Water Risk-Based Clean-Up levels, a groundwater investigation is necessary. The groundwater investigation determines the extent of the contaminated groundwater, and whether it is limited only to the property of the leaking UST or if extends to neighboring properties.

If the samples in the representative well meet the DEQ Ingestion and Inhalation from Tap Water Risk Based Clean-Up levels, no further action would be required.

The 10’ separation boring cannot be obtained due to site conditions, what happens to the investigation?

If a 10’ separation boring cannot be completed due to examples like refusal (rocky soil, etc.) or if the tank is too deep, per the DEQ a Beneficial Well Survey would need to be conducted.

A Beneficial Well Survey determines if a release of hazardous substances has impacted or has the potential to impact groundwater or surface water, through contaminant migration. These determinations will be used for evaluating exposure pathways in human health and ecological risk assessment; for identifying hot spots of contamination; and for selection or approval of remedial actions at hazardous substance clean-up sites.

The DEQ requires the survey to identify all properties that are in proximity to the site with the leaking underground storage tank, which may be utilizing a water supply well. The well may be used for drinking water, irrigation, etc. DEQ regulations considers that any well on a property that is for domestic use, be accounted for. These surveys can and are conducted within and outside city limits.

Grd Water

Groundwater encountered within an opening within an underground storage tank.

Vapor Intrusion from soil or groundwater:

Vapor intrusion is the migration of Volatile Organic Compounds (VOCs) from the subsurface into buildings. Per the DEQ, vapors released from volatile substances can be slowly released from underground spills. These volatile constituents move upward through the pores in the soil, when the soil is exposed during excavation, as well as, from contaminated groundwater. The DEQ requires Soil Vapor Gas sampling (SVGs) to assess the potential of carcinogenic vapors entering residential buildings. When certain constituents of interest, such as benzene, ethylbenzene and naphthalene concentrations exceed the DEQ Vapor Intrusion into Residential Buildings Standards, soil vapor gas sampling would be required.

To assess the potential cancer risks from vapor intrusion into homes, soil vapor gas sampling is triggered if any of the following variables apply:

  • The plume of contamination exceeds 65 cubic yards
  • There are, or likely to be, buildings within 30 feet of Volatile Organic Compounds (VOCs)
  • A 10’ separation cannot be established between the vertical extent and any potential shallow groundwater

Due to site specific factors, the number and sample locations may vary. Sampling may be conducted within the home or on the exterior of the building, either through the sub-slab and/or the soil.

Risk-Based Clean-Up

Soil Vapor Gas Sampling at the exterior of the property

Risk-Based Clean-Up

Sub-Slab Sampling, in the interior of the building

For a more in-depth overview of the DEQs requirements and standards regarding Risk-Based Clean-Up and leaking tanks, please visit their Leaking Underground Storage Tank Program (LUST site) DEQ LUST Site.

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.