Underground Storage -my idea

[Chris S]

Been chewing on this a few weeks now
Instead of buying , modifying & insulating an old pressure vessel ( LP tank or other)
I'm thinking of building an underground tank using ICFs
We've used Owens Corning Fold Form & trained with ARXX ICF's very simple to use, like lego blocks
The OC have 2" of EPS each side of the concrete- my area of choice is wet, so I would probably line the excavation first with a membrane ( EPDM)
Then place some sand for a nice level, consisten base, 2 layers of EPS board and a 6" thick concrete pad with some steel reinforcing ( my days at NCE were not for naught) Then a 6" thick reinforced wall- bathtub if you will fully insulated both sides
Concrete planks for a lid, with more insulation of course
Now i just need to figure out the heat exchangers, piping etc.
OC fold form is a flimsy product- takes a lot of bracing etc. to keep it straight, but in this application true- straight walls are not critical, set up time for a 2000 gallon tank would be about 2 hours- ready for concrete

Any Thoughts on this? I don't want to reinvent the wheel if somebody already worked all of this out- maybe just try & make it a little better.

Chris

 

[Nofossil]

Three things:

1) 4" of foam is pretty minimal when you're looking at a 200 degree difference between water and outside temps. I'd go way more than that.

2) Pay extra attention to evaporation control - sealing the lid so that no steam can escape to condense in your insulation and/or lid structure.

3) If the tank is situated so that someone could walk on the lid, think about how to ensure that could never happen. If the lid structure were weakened and someone fell in, it would be a pretty awful way to die.

 

[Reggie Dunlap]

A pre-cast tank might be easier and cheaper. That's assuming it's new construction and you could crane it into place.

 

[Chris S]

A precast 1500 gallon septic tank will cost me about $ 1300 (uninsulated) A Foldform wall performs like R-50 so I'm not too worried about the heat loss but I'll do some math- more inches= better.
In regards to a cap-my precast supplier will sell me either reinforced concrete planks, or I could buy a precast septic tank lid- they'll hold auto traffic.- some good considerations

regarding delta T- I'm thinking more along the line of 50 degree ground temperature vs 180 degree water = 130 - not as severe, but still considerable.

Are you suggesting that my "tank" should be sealed but not pressurized? Should any consideration be given to pressure build up?

Thanks for your comments,
Chris

 

[leaddog]

You will also have to line the inside with epdm as the foam will absorb water. My son is going to do something simular but his area is dry so moisture is'nt as much a problem on the out side. He is going 8x8x10deep. Big advantage is it is out of the way. His is going to go under his boiler room.
leaddog