Slab for a fuel tank

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Old 05-06-09, 12:35 PM
J
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Talking Slab for a fuel tank

Hello all. My wife and I just purchased a rural home, and our inspector advised us to pull the 1000 gallon fuel oil tank out of the ground to avoid costly issues down the road. So now it's out and the hole has been filled and leveled. I'm just wondering how thick a slab I should pour to support such a load, and what the appropriate reinforcement would be. I want to do this right the first time! Thanks
 
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Old 05-06-09, 12:58 PM
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Wow, that's a big puppy. A couple of thoughts come to mind, outside in Southern Michigan? I know here in Maine they have to mix in some kerosene to keep it flowing in the cold weather and with 1000 gallons, that would mean pretty much the whole year, unless you go through it quicker than I think. But that's another thread. Do you really need that big of a tank?

As for the slab, it will be small enough that even a foot thick with lots of re-bar would be easy and certainly strong enough. BUT. the ground under it might not be. Certainly a problem if you are over the old hole as the ground will settle. But frost will also be pushing that slab around. Make sure the ground is super well compacted and perhaps add some high density rigid foam under and around the slab to control the frost.

Also, you will want to consider where the oil will go if the tank were to split in half. I know, it's not going to happen, but if the contents are headed directly to a stream the costs go out of sight. Make sure your insurance company and the town are happy with your new location.

GL
Bud
 
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Old 05-07-09, 01:44 AM
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Better check on the codes there. The DER has been requiring any above ground fossil fuel tanks must be set in a fashion that if the tank leaks or ruptures the "pad" with "Walls can contain the environmental disaster that could occur. Why such a big tank and if its the old one I would replace it on the get go. Most homes are 275 or 300 gals. Again check specs on codes. Also a 1,000 tank is hard to hide by the house.

Caution don't do this under the slab:

add some high density rigid foam under and around the slab to control the frost.
Will make this worse and its a waste of money not to mention the dead weight crush factor and moving the slab even more. Almost making a mud puddle or liquefying the soil

Your oil will weigh about 6 to 8 lbs depending on the additives. So thats 4 tons on tank feet. 8,000 lbs dead weight. 7" of Crete 4,000 Psi and 1/2 bar 1 foot squared will handle that weight class.
 
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Old 05-07-09, 05:58 AM
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Upon reflection, that will be an awful lot of weight on potentially a very small foot print. Thanks Boat.

But I'm still concerned about soils and frost. If you go containment, then do you need a roof, then you might as well make it a small building. Do you need an extra garage .

Bud
 
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Old 05-09-09, 09:28 PM
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Originally Posted by Bud9051 View Post
Upon reflection, that will be an awful lot of weight on potentially a very small foot print. Thanks Boat.

But I'm still concerned about soils and frost. If you go containment, then do you need a roof, then you might as well make it a small building. Do you need an extra garage .

Bud
Hi bud. The funny thing here is there no widths and lengths to judge by in "foot print"

The 4'000 Psi Is what the Crete can handle per square inch of compression. no worries there. The "bar" keeps it together stopping "shear"

The containment isn't as deep and wide as you would think in walls heights the round to square thing. No roof necessary.

7" thick Crete handles fine when I run tandem axles trucks over my shop apron.

The specs for a two post car lift is 7" at 4,000 psi and less in rebar spacing.
 
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Old 05-11-09, 02:15 PM
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My first question is whether this tank sits on legs or if it distributes the load via a flat surface. If it has, say 4 legs, then you are wasting most of the concrete in between them with a slab. In this case I would use footings, that way you can dig deep enough to alleviate some of the frost heave concern.

If the tank is flat then I would use a slab on heavily compacted soil. Sit the rebar up on 3" soaps to get it up into the concrete, any lower or much higher than that will make it useless. Once the slab cracks, or if it does, steel any less than 3" away from outside edge will be subject to corrosion from excess moisture and air (according to ACI of course). No re bar necessary at the top of the slab, I would us welded wire fabric there to control temperature cracks however. 7" thick, without taking pen to napkin, sounds a little over done but maybe not. Doesn't really matter though, cost wise it won't be to much more. Good luck
 
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Old 05-11-09, 04:09 PM
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Im impressed with the size of tanks you guys down there use.. all Ive ever seen here for above-ground tanks is the 200 gallon (900 L) ones. The standard install package is that the tank comes with threaded 'holes' on welded brackets. I used 4" iron nipples and flanges at the bottom as feet. This rests on 4 patio slabs on sand and compacted fill. This new tank is about 7 yrs old.. hasnt heaved or leaned or cracked the slabs (although I thought it might have.. patio slabs arent that strong are they ?)

Even with the -40's we hit up here, I only have to call in the fuel truck 3 times (we use 2.5 tankfuls). They dont seem to mind.
 
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Old 05-12-09, 10:05 PM
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If it has, say 4 legs, then you are wasting most of the concrete in between them with a slab.
Hi Ohiodraft You need the "slab" to spread the weight out. Independent frost footers can sink out of sink and tilt the tank quicker.
 
 

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