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The most trusted name in residential heating oil
tank services

Phone (503) 244-7002


Email: info@danatanks.com

OR CCB#146791       OR DEQ#19349

�Dana Thompson Tanks & Soil, 2001, 2003, 2004, 2005, 2006, 2007, 2009

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What the Law Requires

Locating Underground Storage Tanks

Tank Sizes

Heating Oil Tank Program And Certification

Tank Decommissioning

Initial Site Assessment, Soil Sampling

Reporting a Release

Cleanup Options
      Soil Matrix Cleanup
      Risk Based Decision Making
      Generic Remedy


Consumer Tips

Understanding Laboratory Reports













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Dana Thompson Tanks & Soil has earned its broadly accepted position as the premier residential heating oil tank contractor serving Western Oregon. DTT&S has established and maintained the highest standards of customer service and quality workmanship in the industry. We have attracted and maintained the highest quality employees by providing an excellent pay package, medical and dental benefits, paid vacations and paid holidays. With the exception of new or temporary employees, 100% of DTT&S personnel are DEQ licensed Heating Oil Tank Supervisors.

The first HEATING OIL TANK HANDBOOK was published in 2001, and it has remained the most complete and concise treatment of the subject available. The handbook is designed to assist real estate professionals, developers, contractors and homeowners in understanding the rules, regulations and common practices involved in heating oil tank decommissioning and cleanup. This handbook is intentionally general and based on my interpretation of DEQ documents. For verification or details, please contact the DEQ.

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Active residential heating oil tanks, tanks which currently provide fuel to a building�s heating system, are not regulated by Federal or State law. These are the regulations which apply to abandoned heating oil tanks (tanks which no longer provide fuel to a heating system) and to tanks where a leak is suspected or confirmed.

1. When a tank is abandoned, it must be pumped of remaining oil and that oil must be disposed of properly. If oil remains in the tank, it must be removed prior to a property transaction. Documents relating to disposal of oil should be retained.

2. It is unlawful to remove the vent pipe from an abandoned tank until that tank has been properly decommissioned.

3. Oregon law requires that any suspected or confirmed release of petroleum from an underground storage tank must be reported to the Oregon DEQ within 72 hours of discovery.

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Any house built before the mid-1960s and which has a central heating system is likely to have or have had an underground heating oil tank. Sometimes evidence of an underground tank can be found in the basement of a home, or the vent or fill pipe are visible outside of the house. If you suspect the home may have had oil heat at one time, you may want to have a tank search performed. If there is a vent pipe on the outside of the home, or you are certain a tank is present in a general area, Dana Thompson Tanks & Soil will gladly visit the property to perform a free tank search if that search is associated with an initial site assessment soil sampling event. .

There are many companies, including some Heating Oil Tank Service Providers, which charge for tank locate services. We are not aware of any HOT SPs who have the equipment, background and training necessary to perform tank locate services for a fee. We believe there is only one company qualified to charge for such services and that company is Geopotential, a highly qualified geophysical exploration company. You may reach Eddie Kahl, Geopotential's utility locate expert, on his cell phone to schedule a search: 503.740.0530..

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Underground heating oil storage tanks are typically horizontal cylinders. Although, sometimes we find odd sized tanks, these are the most common residential tank sizes:

Volume in gallons
46" x 96"
48" x 48"
45" x 72"
36" x 72"

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Heating oil tanks are considered unregulated tanks. In the past, leaking oil tanks were regulated under the DEQ's Underground Storage Tank (UST) program, and there was no way for the DEQ to store information on tanks which had not been reported as leaking. File closure through the UST program was awkward, time consuming and costly.

In 2000 the DEQ created the Heating Oil Tank (HOT) program to deal with the cleanup of leaking heating oil tanks. The HOT program also includes a Voluntary Registration program for tanks which have been decommissioned and where a valid site assessment has shown that no reportable release has occurred. Tank certification under the Voluntary Registration program creates a permanent record of the property. The certification option provides an incentive for property owners to investigate and properly address Underground Heating Oil Storage Tanks.

The DEQ�s HOT program allows third party certification of decommissioned heating oil tanks and environmental cleanup by DEQ licensed service providers. All DEQ licensed HOT service providers are required to have professional liability insurance for errors and omissions in the amount of one million dollars. When a service provider in good standing submits a thorough report, signed DEQ forms, a certification letter on company letterhead, and the appropriate filing fee to the Heating Oil Tank Program, the DEQ then accepts and registers the contractor's certification. The Department will then issue a letter to the tank owner registering the contractor's certification. This is equivalent to the "No Further Action" letter that the DEQ previously issued.

The DEQ filing fee for the voluntary registration program is $75.00 and the filing fee for cleanup certification is $200.00. On extremely complex sites, the DEQ is now considering additional fees to cover additional staff time in the review process.

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A tank is properly decommissioned when it has been thoroughly cleaned and completely filled with a compacted solid, inert material. This material can be sand, pea gravel, crushed rock, perlite, standard concrete or control density fill material (CDF).

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*Please note that Oregon Law does not require soil samples except for purposes of registering a tank with the Oregon DEQ�s Voluntary Heating Oil Tank Registration Program.

An initial site assessment is conducted in an attempt to determine whether a tank has released heating oil to the surrounding soil. Samples and analysis are almost always required by a purchaser of a property where an underground tank exists if that tank has not already been certified under a DEQ program. Soil samples can be collected and analyzed before decommissioning, as in the case where a tank is still in use, or samples can be collected at the time of the decommissioning. Sample location, collection, handling and analysis are defined by Oregon regulations to include:

1. One sample from each end of the tank: from outside the tank within 6� of the ends and greater than 1� below the tank bottom; or from inside the tank, beneath each end of the tank within 1� of the tank bottom
2. Samples are to be placed in clean jars and refrigerated at less than 42 degrees F.
3. Samples are transported under chain of custody to a licensed laboratory.
4. To be valid, samples must be analyzed within 14 days of collection, using method NWTPH-Dx

NOTE: Sample results may be used for certification if decommissioning takes place within 90 days.

A clean sample does not guarantee that the tank has not begun to leak. All underground tanks will leak eventually. If it hasn�t leaked, it will.

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The Oregon Department of Environmental Quality (DEQ) requires that any site where a soil sample lab analysis shows petroleum concentrations of 50 ppm (parts per million) or greater must be reported to DEQ within 72 hours. The DEQ will open a permanent record and assign a file number to the property.

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The Oregon DEQ provides three options for cleanup of sites where a release of petroleum has occurred.

NOTE: Cleanup requires the heating oil tank be decommissioned, thus removing the source of contamination. The following is a brief description of the cleanup options. For more detailed information, consult the DEQ's website, where the guidance documents for these cleanup approaches may be found.


The DEQ developed a matrix scoring method which applies a point value to site specific conditions. Any site with a score of 40 points or lower, qualifies for Level II Soil Matrix Cleanup. Most homes in the Portland metro area are Level II Soil Matrix Cleanup sites. Level II Soil Matrix Cleanup is achieved if the most contaminated soil on a site contains less than 500 ppm TPH. When a soil sample collected before or during tank decommissioning on a Level II site contains more than 50 ppm TPH, but less than 500 ppm TPH, the release must be reported, but usually the site will meet cleanup standards without further site work.


The Oregon DEQ�s Risk Based Decision Making (RBDM) Guidance Document establishes the criteria and methodologies which determine whether petroleum impacted soil from a heating oil tank (HOT) release poses a risk to human health and the environment, and whether such soil must be removed. The RBDM approach requires that we analyze the most contaminated (representative) sample to identify concentrations of petroleum constituents. We compare the laboratory results to the RBDM document�s table of minimum risk based concentrations (RBCs: think threshold). The RBCs are listed separately for each possible pathway to human exposure. If any constituent concentrations exceed the minimum RBC for a given exposure pathway that exposure pathway must be explored and eliminated from concern. On residential heating oil cleanup projects the two exposure pathways most commonly addressed are �Leaching to Groundwater and Subsequent Human Ingestion� and �Volatilization and Vapor Intrusion to Indoor Airspace.� The �Leaching to Groundwater� pathway usually presents no challenges unless contaminated soil is found in contact with groundwater, or there is a well in the immediate vicinity of the heating oil tank release. Exploration of the �Vapor Intrusion� pathway has frequently been required due to high benzene concentrations. In most cases use of a simple spreadsheet evaluation tool, provided by the DEQ, will demonstrate that the ratio of benzene to indoor airspace does not pose risk to the home�s occupants.

Prior to January, 2009, the naphthalene RBC for the �Vapor Intrusion� exposure pathway was 160 parts per million (ppm), far above any concentrations we�ve seen on a heating oil cleanup site. Later, due to the U.S. Environmental Protection Agency�s reclassification of naphthalene from non-carcinogenic to carcinogenic, the RBC was changed to 4.5 ppm, and eventually 6.5 ppm. When naphthalene is present in concentrations greater than 6.5 ppm on any heating oil tank cleanup project, a vapor risk assessment is required before the site can be certified.


The Generic Remedy cleanup option is a simplified Risk Based Decision Making process. The new screening levels for ethylbenzene and naphthalene will likely spell the end of the Generic Remedy option in most situations.

The unique features of the Generic Remedy are:
1. No groundwater is encountered
2. Soil sampling demonstrates that no more than 65 cubic yards of
        contaminated soil remains on the site.
3. All contaminated soil is located at least 3' below ground surface
4. The most contaminated soil remaining on site contains less than
        10,000 ppm TPH and less than 0.0083 ppm benzene, less than 0.14 ppm
        ethylbenzene and less than 0.072 ppm naphthalene
5. No PAH analysis is required
6. If the most contaminated soil samples shows petroleum concentrations
        below 2500ppm no BTEX analysis is required.

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Oregon has many areas where near surface groundwater may be encountered. When groundwater is encountered on a site where a release of heating oil has occurred, it must be reported to the DEQ. Encountering groundwater may necessitate removal of contaminated soil and will require additional risk assessment conducted by a qualified professional geologist.

Sometimes after a tank is installed, soil beneath and around a tank may settle or shift to create a void between the tank and soil where water can collect. Also, due to a tank's proximity to a home's roof and yard drainage systems, soil around a tank can be saturated to a point where any hole created will collect water. It is not uncommon to discover perched or trapped water when initial soil samples are collected, or to have water enter a tank after it has been thoroughly cleaned. This is not necessarily a sign that a groundwater issue exists.

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1. Always check the DEQ and Construction Contractors Board license status of a contractor under consideration. More importantly, call the DEQ and inquire about a contractor's history and whether the contractor has been issued Notices of Non-compliance (NONs).

2. Discovery of groundwater can add considerable expense to a project. When water is encountered during initial soil sampling it is often a result perched (trapped) water or saturated soil. If a contractor proposes a groundwater investigation after discovering water during initial soil sampling, get a second opinion.


Q: How long do buried tanks last?
A: The DEQ puts the life expectancy of underground oil tanks at 15-20 years. We have encountered leaking tanks which were only two years old, and sixty year-old tanks which have not leaked.

Q: What are the chances that my tank has leaked?
A: Eventually, all underground tanks will leak. If it hasn�t leaked, it will.

Q: What are the costs for tank decommissioning and environmental cleanup?
A: Most tanks can be sampled and decommissioned for around $1,000. Decommissioning and Risk Based cleanup will usually cost between $2,500 and $3,000. Excavation and soil removal projects usually cost between $3,200 and $5,000.

Q: My tank is decommissioned, but I don�t have any paperwork. What do I do.
A: We can collect new site assessment samples and, while on the site, perform the work necessary to confirm the previous work was done correctly. We can then complete all reports and certify the project under the Heating Oil Tank Program.

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Most laboratories present the soil sample analysis data in columns with headings for sample ID, diesel results, heavy oil results and surrogate recovery. A sample�s field ID will often offer information about the location and depth of a sample. Diesel and heavy oil results are expressed in mg/kg or parts per million (ppm). The surrogate recovery column contains lab quality control information only.

A BTEX analysis identifies concentrations of benzene, toluene, ethybenzene and xylenes. A PAH analysis identifies concentrations of a number of polynucleic aromatic hydrocarbons. Benzene, ethylbenzene and naphthalene are the constituents which will drive cleanup requirements.

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Quick Reference for Soil Sample Laboratory Results
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If your sample results show:
ND (non-detect) diesel & heavy oil No leak is detected or no action required
< 50 ppm TPH (diesel or heavy oil)Indicates a tank leak, but reporting not required
> 50 ppm TPHThe release must be reported to the DEQ
< 500 ppm TPHMay already qualify for Level II Soil Matrix Cleanup
< 10,000 ppm TPHMay Qualify for Generic Remedy Cleanup
> 10,000 ppm TPHMay Qualify for Risk Based Cleanup
> or = 60,000 ppm TPHSome impacted soil must be removed
> 0.0084 ppm benzene or
> 0.14 ppm ethylbenzene or
> 0.072 ppm naphthalene
leaching to groundwater and subsequent
human ingestion exposure pathway must
be explored
> 0.068 ppm benzene or
> 0.69 ethylbenzene or
> 4.5 ppm naphthalene
intrusion to indoor airspace
exposure pathway must be explored
or contaminated soil removed

(Phone) 503-244-7002 (Email) info@danatanks.com (Fax) 503-244-6267
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