Causes of Leaking Underground Fuel Oil Tanks?

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Old 10-23-11, 11:46 AM
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Causes of Leaking Underground Fuel Oil Tanks?

Some qustions:

How did you first discover the tank was leaking? How many gallons leaked, do you think?

What was the cost of the whole mess?

Did they leave supports under the slab and footings, and fill in around them? Otherwise, how did they sufficiently recompact the soil for structural support?
 
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Old 10-23-11, 12:49 PM
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Gil, the tank was removed prior to putting the home on the market... which is now five years behind schedule because they STILL are not done cleaning up... the contamination ran underneath a private road which is the sole access to six other homesteads... and under a neighbors yard... alternate access is impossible...

The leak was discovered when the tank was removed. There were no signs or clues of the leak. (I did have my fears though... ) Boiler ran fine, didn't appear to be excessive fuel usage. Was probably leaking for 20 years.

Total cost for the remediation is going to top out around a quarter mill by the time all is said and done.

Yes, the helical piers are in place, down 23', encased in 4" PVC filled with concrete. There are actually more than appear in the pics, the excavation got larger as the contamination was followed underground. They run all the way to the end of the building on the right side, and around the corner. Maybe 6 or 8 more piers.
 

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Old 10-23-11, 02:27 PM
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Does it kill you that if that tank didn't leak you would have sold at the height of the market?
 
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Old 10-23-11, 02:43 PM
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Causes of Leaking Underground Fuel Oil Tanks?

Is it corrosion from the outside or the inside of the tank? Possibly physical damage to the tank due to soil shifting or heavy loads running over the tank? Is it mainly steel tanks that develop leaks or are fiberglass tanks also prone? Aren't steel tanks coated on the outside with some type of bitumastic to help prevent corrosion?

Trooper, after your tank was pulled, could you tell where the leak was?
 
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Old 10-23-11, 03:51 PM
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Hmm - interesting info. Thanks.

In the Midwest, many people use propane for heating, particularly in rural areas not served by natural gas. Most if not all propane tanks are above ground, usually 50+ ft behind the house. I wonder why so many fuel oil tanks are buried?

Maybe it's pressure? Propane will flow "uphill" due to the vapor pressure of the gas. (Large commercial or industrial propane tanks may need a fired evaporator when the outdoor temperature is very cold, but residential-size propane tanks don't.)
 
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Old 10-23-11, 04:04 PM
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I don't think many new tanks are buried any longer ever since the disaster of leaking oil tanks started. I'm not even sure if it is allowed unless the tank is plastic. I suppose they were buried simply to keep them out of sight. No one cared about the environment back in the 40's and 50's when they buried them all.
 
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Old 10-23-11, 05:39 PM
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New tanks are buried every day in commercial and industrial work BUT they are double wall tanks with some fairly sophisticated leak detection systems. The cost to do this in residential service would have anybody looking for an alternative..

Buried tanks will corrode from either the inside, the outside or both depending on several variables. In residential service I would do just about anything to avoid a buried tank.
 
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Old 10-23-11, 08:59 PM
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Does it kill you that if that tank didn't leak you would have sold at the height of the market?
Yeah... don't remind me! Even though this remediation is covered by insurance, I STILL lost about 150K because of the real estate market... Grrrrr...

The bottom of my tank was like swiss cheese... thankfully the bottom of the tank was filled with about 9" of sludge and I'm sure this slowed the leakage.
 

Last edited by NJT; 10-24-11 at 04:10 PM.
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Old 10-24-11, 03:37 PM
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So I sent your album to my brother to look at and gave him the back story. He one-upped me with this little story: Kirtland Air Force Base - Wikipedia, the free encyclopedia
 
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Old 10-24-11, 04:07 PM
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Ya really gotta wonder how in hades it's possible that much jet fuel has been leaking for 60 years and not noticed... what kinda bozos do we have running this country?

My theory is ELECTROLYSIS.

My tank was installed within 2 feet of my home's electrical service entrance. The ground rods for the service may have even been closer.

Same manufacturer of tank, installed same day in 1952, at the same depth in the ground, by the same two guys ( a relative and his neighbor, first hand info ), on the OPPOSITE corner of the house from the electrical service was perfectly intact.

The guys who removed the tank told me that they see many more 'leakers' installed near ground rods for electric service.

I don't know if this has or why it hasn't been studied, but it would seem that it should have been common knowledge to tank installers back in the day... but maybe nobody though about it? Are we REALLY smarter now? or do we just think we are?
 
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Old 10-25-11, 05:03 PM
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Could you tell if the tank had been protected with an exterior coating?

Electrolysis induced by your AC ground rod is a definite maybe, at least in my mind. Steel ships in the U.S. Navy use ungrounded electrical systems - for personnel safety and also, supposedly, to prevent electrolytic corrosion of the ship's hull during a half-cycle of the AC power waveform - even though ships' hulls are protected with sacrificial zinc anodes (that are routinely replaced from time to time). For a buried steel tank, I would want some type of cathodic protection, but not sure how practical that would be for a residential oil tank.

Buried steel pipelines are usually provided with cathodic protection - a DC voltage is applied to the line and monitored from time to time to make sure it's working.
 
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Old 10-25-11, 05:51 PM
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No, there was no bitumen coating on either tank. I don't think it would have helped, it appeared that the rust 'craters' formed from the inside out.

I'm familiar with cathodic protection, and I wonder why tanks don't have anodes... but maybe the fuel oil is not a good electrolyte. I would think that the anode would need to be in an electrolyte to function.

Those big pipelines use 'Impressed Current Cathodic Protection', and the power supplies that serve the purpose of providing the current often are connected to wireless systems that can be monitored from a distance.

There is at least one 'ICCP' system designed for domestic water heaters... basically a 'wall wart' and an anode.

Powered Anode for Water Heaters With Hex-Head Anodes and a deep anode port: What it is and what it does

If the darn thing weren't so pricey, I'd have one in my water heater right now!
 
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