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How to clean underground oil tank?

Rtraveler1 Member Posts: 8
I have a 1945 H.B. Smith boiler which uses oil. The oil tank is underground and when the oil level is 12 inches or lower, it doesn't run consistently. It shuts off and I think it's because of all the residue/soot on the bottom of the oil tank. I have put in new filters but it doesn't help.

Does anyone know how I can clean the oil tank to remove all the residue/soot. Thank you.


    EBEBRATT-Ed Member Posts: 15,612
    oil tank

    If it's a 500 or 1000 gallon tank you probably can't clean it. The larger tanks have manholes on them for cleaning but smaller tanks do not. Three things you can do for a short term solution:

    Don't let the tank get low on fuel

    Use fuel oil treatment

    Re pipe the burner suction line so it is not near the bottom of the tank. Suction lines are usually 6" above tank bottom.

    I am more concerned with the age of your tank and the possibility of an undetected underground leak which could get expensive.

    My best advise would be to abandon it and have it removed and install indoor tank(s)
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505

    This could be a vacuum issue. Did anyone check? I would fully investigate this first. You may solve the problem changing it to one pipe from the tank and adding a tiger loop.

    The boiler is almost 70 years old. How old is the tank?

    Crud on the bottom is on the bottom whether the tank is full or empty. What does the oil look like? You could have the oil analyzed and an additive regimen could be recommended.

    There was an error rendering this rich post.

  • icesailor
    icesailor Member Posts: 7,265
    Cleaning UST's

    The best way to clean a underground oil storage tank is to remove it and replace it with a UL listed tank that your insurance and local AHJ's will approve.

    I don't know what State you are in but most States that have UST's have mandated that they be removed, inspected for leaks, cleaned up if necessary and replaced with approved and monitored tanks. Does your insurance company know you have a UST and are they covering it if you have a spill? It's my understanding that if you do not have approval from your insurance companies NOW, they will not cover you for a spill.

    That's what happened to all the old gasoline stations. They had to replace the old tanks and couldn't afford it because they didn't sell enough gasoline. And if your tank leaks and contaminates the soil and ground water, you don't have enough money to cover the liability expenses.

    Also, if you have trouble when the oil level gets to 12" from the bottom, that is the level that the lines are from the bottom. The bottom 12" of the tank is nothing but a matt of sludge, As more sludge forms, it just gets sucked in to the burner filters. You can suck all that sludge off the bottom but it will come back. A oil salvage/tank recovery company can do it but probably won't because I think that EPA and some State regulations require they do a tank inspection and if they deem that the tank should be removed, they can be liable if you don't. As you too
  • Jamie Hall
    Jamie Hall Member Posts: 23,426

    in some States -- mine, for example -- it isn't even legal to have an underground tank that old.

    And as Ice so neatly said -- if that tank leaks, you don't have enough money to pay for the cleanup (unless maybe you are Bill Gates in disguise).

    You have a bit of a dilemma there.  You should abandon the tank; if you want to keep an underground tank, you can put in a new one, but they are not inexpensive and require monitoring (at least in many States).  If you abandon the tank, you have basically two choices: either not tell anyone about it, and hope that it hasn't leaked and that you don't have any contamination, or tell somebody about it -- and hope that it hasn't leaked and you don't have any contamination.  The second route has the virtue of being legal...

    And I never heard about your having an old underground tank, by the way, if anyone asks.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • billtwocase
    billtwocase Member Posts: 2,385
    all good advice here

    I have also found copper supply lines that have coiled upwards. Had another one that was 1000 gallon thank, and would run out at 1/2 tank. I would get rid of it, and instal one above ground
  • icesailor
    icesailor Member Posts: 7,265
    Leaving Tanks:

    In SOME States (My former one), if removing the tank could cause the loss of structural integrity of something (like the building falling in the hole), at the AHJ's discretion, they can allow you to leave it in place if they ascertain that is hasn't leaked in the ground, you dig up the top and cut it out. Then, THOROUGHLY clean the inside for inspection. If approved (passed, you are allowed to fill the existing tank with clean sand and leave it in place. I did one in a parking lot where the building foundation could have a problem and the bottom of the tank was in groundwater. It was allowed.