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Assessing Underground Storage Tank Integrity

There are tens of thousands of residential and commercial underground fuel oil tanks still in service in the US.Many of these tanks were installed during the energy crisis of 1973-74; others were installed even earlier. US EPA studies show that most steel tanks over 25 years old lose their integrity! There is also substantial evidence that overfills of residential tanks occur on a regular basis; many of these spills are never reported. It is important to have a means to test soils around underground storage tanks if:

-The property is being sold or the mortgage is being refinanced

-The tank is constructed of steel and is over 25 years old

-There is evidence of substantial water in the tank

WC Environmental, LLC utilizes GeoProbe® drilling units designed to quickly and efficiently sample soils from around the bottom of underground storage tanks, regardless of their location. Findings can be reported based on either field or laboratory analysis; a report (with color photos documenting the assessment) is issued with conclusions and recommendations, as appropriate. We can also provide you and your buyer (or seller) with all the options for managing underground storage tank concerns. Our lead time for beginning work, after the mandatory three day delay for a utility search, is often less than one week, with a report usually issued within two weeks of authorization to proceed.

Underground Storage Removal Vs. Closure in Place

Closure of underground storage tanks should be performed whenever a tank is taken out of service permanently. Failure to do so can result in the release of regulated materials at some time in the future, since steel tanks invariably rust and residues nearly always remain in tanks that have been emptied by all practical means. This is a requirement for all tanks regulated by the PA Department of Environmental Protection; regulated tanks include virtually all storage tanks except those used to store heating oil for on-site use as well as most farm tanks.

The following table provides some pros and cons of the two closure methods:

Issue Removal Closure in Place
Definition Physical removal of the underground storage tank, usually using a backhoe or other excavation equipment. Regulated tanks must be removed by a PA Certified Installer/Remover. Non-regulated tanks are exempt from that requirement. Closure in place is usually performed when the tank is under or partially under a building or other structure, or when excavation equipment cannot be used. Involves some physical cleaning of the tank and filling with an inert material./td>
Environmental Liability Provides permanent release from liability (only for regulated tanks) if 1) post-excavation sampling is performed according to state closure criteria, 2)results are below regulated limits and 3)a formal closure report is submitted to the State. Provides permanent release from liability if 1) post-closure sampling is performed adjacent to the bottom of the tank(s), 2) results are below regulated limits, and 3) a formal closure report is submitted to the State.
Advantages -Elimination of future liability if closure is properly documented.
-No tank remaining to interfere with future construction.
-Only method of closure when tank is inaccessible.
-If a manhole is present, cleaning can be done easily and the project may cost less than removal.
Disadvantages -Often more expensive than closure-in-place
-May result in disruption of site operations
-Removal activities may be difficult or dangerous if there are other sub-surface utilities in the immediate area
-If means to access tank for cleaning is not convenient, may actually cost more than removal
-May conflict with future construction activities
-Accurate sampling is more difficult since the actual underside of the tank cannot usually be reached easily.
Other Factors -PA DEP, other states encourage removal when tank is accessible
-Requires utility search
-PA DEP, other states encourage closure in place when tank is inaccessible

*Regulated tanks require 30 day notification to the PA DEP Regional Office and a copy to the State Department of Labor &Industry prior to removal. Be sure to check for utilities before doing any digging!*

Tank Testing Vs. Low Intrusion Soil Sampling Storage Tank Evaluation

Tank Testing WC Environmental Low Intrusion Soil Sampling
Cannot determine if soil is contaminated from historic leaks or overfills. Readily identifies contaminated soil.
If the tank has leaked, cannot determine how much product has escaped or where it has gone. Can be used to determine horizontal and vertical extent of contamination.
Tests may not be accurate when there is a high water table or low permeability soils. Accurate regardless of soil groundwater conditions.
Tank cannot be accessed during test./td> Tank can be accessed during test.
Frequently cannot identify leaks in pipes. Identifies contamination regardless of source.
Raw data available in 4 – 6 hours but frequently is difficult to interpret. The final report can take weeks. Raw data available in less than 1 hour, report in as little as 4 hours.
Short report with little useful information. Report with printed site map showing location of tank, soil samples, full color photo documentation. Field analysis using PA DEP recommended screening equipment provided. Laboratory analysis is provided when contamination is noted.
Not legally defensible Legally defensible
Cost: $900-1200 Cost: $1400-2000

Frequently Asked Questions About Residential Underground Storage Tanks

Q: If I have an inactive underground storage tank, do I have to do anything about it?
A: No, but if you intend to sell your house, you might want to consider either removal or closure-in-place. This will relieve the buyer and his mortgage company over possible contamination from releases.

Q: If I am buying a house, should I be concerned about possible releases from an underground tank left by the seller?
A: If the property is sold in “as-is” condition, and the seller has informed you of any “known” environmental problems, then the liability for part and future releases is all yours. The prudent course of action, and one that might be required by your mortgage company, is to make sure the tank has not leaked.

Q: What is the difference between removal and closure-in-place?
A: Removal involves excavation of the tank, cleaning and disposal of tank residues, recycling of the tank and backfilling. Closure-in-place involves removal of tank residues followed by filling the tank with an inert substance (typically cement). Both methods should also involve a mechanism for making sure that overfills or leaks have not contaminated groundwater supplies; this is best done by having soil samples taken from underneath and/or adjacent to the tank bottom for analysis. This relieves the owner of future liability associated with prior releases. While tank removal is a little more expensive, if contamination is found during an assessment, it is easier to deal with the problem if the tank has been removed. Removal also eliminates any future questions regarding the tank.

Q: How can I make sure and underground storage tank has not leaked?
A: There are basically two different methods – tank tightness testing and soil borings around the bottom of the tank. The tightness testing method can tell if there are holes in the tank, but not if there have been substantial overfills resulting in contamination. (See information below on tightness testing vs. soil sampling.)

Q: How common are underground storage tank leaks?
A: According to Environmental Protection Agency data, the majority of all steel tanks over 25 years old leak. Newer fiberglass tanks (typically installed since about 1985) almost never leak. Even if the tank is in perfect condition however, the piping that leads to the house may not be. The greater the distance and number of pipe joints, the greater the likelihood of a problem.

Q: All the houses in my area are on public drinking water supplies, there aren’t any private wells around. Does it matter if an underground fuel storage tank leaks?
A: Yes, if your tank leaks and impacts groundwater, the contamination may travel for miles depending on local geological and soil conditions, impacting public wells, springs, surface waters and deep aquifers. You could be liable for any cleanup costs.

Q: If my oil supplier accidentally overfills my tank, am I responsible for any contamination that might be caused?
A: If the overfill is obvious, the supplier will generally pay for any necessary clean-up. Unfortunately, there isn’t always a lot of physical evidence of overfills, and a few gallons a year over a twenty or thirty year period can cause a great deal of contamination. If the contamination can’t be traced to the overfill, the owner would be liable for any cleanup costs.

Q: What can I do to help prevent overfills?
A: Make sure the tank fill pipe is easily accessible and visible. If possible, pave or line the area around the fill pipe with an impervious material such as plastic sheeting. The plastic can be buried a few inches underground and then covered with dirt and grass or other landscaping.

Q: If my tank leaks, what should I do?
A: The PA Department of Environmental Protection requires reporting of all petroleum releases greater than one gallon. Prompt action in the form of removal of the contaminated soils and/or treatment of soils can substantially reduce the spread of contamination.

What Environmental Work Should Cost

This section provides a framework for what environmental work “should” cost. It includes applicable rate ranges for work we perform; also provided for your information are some typical cost ranges for certain types of work we do not perform, including underground storage tank removal. Rates for site work is typically for Southeast Pennsylvania. Costs will vary for other locations.

Environmental Project WC Environmental Rates Typical Industry Rates
Phase 1 Environmental Site Assessment, ASTM standard 1527-00 $1750 $2000 – $5000
Phase 2 GeoProbe soils survey (does not include field supervision, report or analysis) $1500 (up to estimated 10 soil borings) $1900-$2500
Underground storage tank soils assessment, with field analysis and report (does not include lab analysis) $2500 – $3000 $3500 – $5000
Underground Storage Tank Removal (1000 gal or smaller) We will gladly refer you to qualified, certified vendors $3500 – $2800
Underground Storage Tank Closure-in-Place (1000 gal or smaller) We will gladly refer you to qualified, certified vendors $2000 (+soil assessment cost)
Underground Storage Tank Removal/ closure (2000 gallon capacity) We will gladly refer you to qualified, certified vendors $2800 – $3200
Underground Storage Tank Removal/closure (3000 closure) We will gladly refer you to qualified, certified vendors $3000 – $3500
Above ground storage tank – install leak detection system We will gladly refer you to qualified, certified vendors $6000-$7000
Install 275 gallon AST in basement We will gladly refer you to qualified, certified vendors $1500


What is mold, and how does it become a problem?

Mold is a type of fungus that appears on the surface of organic materials in damp conditions. Molds may be gray, black, green, yellow, orange or various other colors, and individuals with specific allergic conditions may have a significant reaction to air-borne mold spores. Both indoor and outdoor mold and fungus have been shown to represent a huge allergy problem for many individuals. There are three primary factors always associated with mold growth – temperature, nutrients, and moisture. Mold and fungus need humid conditions in order to live and grow.

Most molds must get their nutrients (food) from the environment, living and feeding on dead organic matter. Outdoors, molds are very important in nature, as they aid in decomposing organic materials and recycling nutrients. Indoors, many building components and contents contain materials that are excellent food sources for mold, such as wallpaper glue, some paints, greases, paper, textiles, wood, and wood products. Indoor dusts may contain fibers, dead skin cells, and other organic matter that can serve as a food source for mold when adequate moisture (greater than 15%) is available. Mold can grow on concrete or stone when sufficient organic matter is present to promote growth.

Temperature also affects mold growth. Different types of mold have minimum, ideal and maximum temperature ranges for growth. Most molds grow well at temperatures between 60 – 80 degrees F, which represents normal indoor temperatures. The following table describes ideal conditions for indoor mold growth:

Factor Range Comments
Temperature 60-80 F Some molds can survive at colder or warmer temperatures
Relative Humidity >60% Measurement of amount of water in air compared to the amount of water that the air can hold
Moisture >15% Moisture greater than 20% almost guarantees mold conditions

Mold Treatment

The best way to eliminate mold is to eliminate mold growth conditions. Proper ventilation can help considerably; a dehumidifier, fans, and/or air conditioner will generally reduce moisture levels. Spraying with a oxidizing solution such as household bleach may kill mold, but it will not eliminate mold conditions for long. It is important to note that while disinfectants and biocides may kill mold spores and take away their ability to reproduce, these products should not be used alone in addressing a mold problem. Either the mold must be completely removed from the affected material, or the mold-contaminated material must be completely removed from the building. Airborne spores are often present, and can resettle on treated surfaces if mold conditions are still present.

When deciding which materials can be treated and which should be removed, the important factors are how porous (absorbent) the material is and the degree of mold growth. If material is completely permeated (wet carpet, upholstery, drapes, ceiling tiles, wallboard, paneling, etc.) it must be removed. It may be extremely difficult to completely remove or treat mold from these materials successfully. Generally, non-porous materials ( metals, glass and plastics) and semi-porous materials (wood, plaster and concrete) that are visibly moldy but structurally sound can be successfully treated.

Cleanup and mold removal activities can expose people to mold particles and other hazards, so it is important to wear protective equipment and follow safety procedures. Large projects require careful planning and implementation to be safely and effectively productive.

If mold conditions persist after treatment, it is because the conditions for mold growth have not been eliminated! Regular inspection of problem areas is a key to preventing mold recurrence.