Anyone know about pouring concrete footings w/ high groundwater table?

[patandchickens]

(No offense, but I'm hoping for Actual Experiences or contractor-type knowledge, not 'it says on the bag' or 'it seems to me', which I can do myself <g>)

OK, my turn to ask a construction type question

Does anyone know how bad it would be to try to pour concrete footings for posts (this is for a shed-roofed chicken run), in sonotube, when the water table is high enough that the holes flood fairly quickly if not bailed frequently? I have a feeling it might mess up the strength of the concrete, but I am not really all that experienced with cement type stuff (just doing this type stuff in good weather, and patching slabs, and repointing brickwork) so maybe I'm being overparanoid.

If it *would* be a significant problem, then does anyone know a LEGITIMATE workaround (I can think of a couple possibilities but have no idea whether they'd produce a strong enough durable enough result)?

I really really really ought to use sonotube and concrete footings for these particular posts, as they're in an area that floods periodically and the ditch runs near our well and I would very much rather not bury p/t wood there (plus this will be, basically, a big roofed shed and I don't want the posts rotting out completely in ten years).

Thanks,

Pat

 

[ncCHICKS]

It won't dry properly

 

[Omran]

WELL I do construction for living and infact in 2006 I pourd footers for a singel wide trailaer and used the sonatubs.

What you need to do first is having a lazer to do your survay and the hights you need to build on.
2- if you need to do any levaling go ahead and do it now.
3 you need an Auger with minimum of 24" bit to drill for the tubes.
4 you need some gravel # 57 to fill around the tube after you set it.
5 you need some rebars to put enough strength in your tubes.
6 check your gradeand pour your concrete and get a concrete truck ask the for 3500 mix and you are in business.
enjoy it.

Omran.

I forgot make sure your holes at list 36" deep.

 

[patandchickens]

Quote:
Yes, I know how to do sonotube footings and have done it a number of times (I will be using bagged mix, btw, as I am only using 8" tubes, these are for 4" posts for a light shed).

What I was hoping to find out is, will high groundwater prevent a decent cure?


Pat

 

[Omran]

I believe it will work if you packed the bottem of the hole with enogh rock and make the hole a little deeper. and I will compact my rock for best results.

Omran

 

[patandchickens]

Omran, I'm not talking about a little seepage that you can drain down away -- I'm talking about 'the hole fills up with water', like, in a way that no amount of deeper-hole-and-gravel-at-the-bottom is going to make any dent in at all

I am wondering now (from a suggestion over on SufficientSelf.com) whether I could tape the heck out of some heavy plastic to make a sort of 'bag end' on the bottom of the sonotube, so that the whole thing is (theoretically) contained and not directly exposed to the groundwater, at least not until the concrete has started curing. I'm not sure how good a waterproof and mechanically-sound seal I could get though. Don't wanna pop for those Bigfoot things either. Hmm. I really really need to get these footings in, but don't want to make trouble for myself down the line by doing a half-assed job...

Pat

 

[LittleChickenRacingTeam]

Pat, the problem you are going to have with pouring regular concrete, is that it wants to seperate into it's individual components when in contact with water. That being sand, cement and gravel.

Concrete requires no oxygen in order to set so that is not an issue.

If you are dealing with a hole that will continue to rise with water, you need to use UNDERWATER CONCRETE MIX.

This is the same stuff they use when building tunnels under bodies of water...like the English Chunnel.

 

[3 sisters farm]

Yes it can be done with quickcrete. I'm not a contractor...but my dad was a bridge engineer, and I watched what they did with my addition and deck. Dig your hole for the sono tube 36" or so based on frost. Put a couple of inches of gravel in (coarse like driveway gravel) then put the sono tube in surround the outside with more gravel. Then pour like one sack of the quickcrete in...pour just a the powder no added water, mix, if not fairly stiff add more about 30# at a time. Now at this point if the mix is stiff you could add prepared quickcrete or if watertable extremely high could let this cure overnight pump out the water in the sonotube the next day and add prepared quickcrete to fill the tube. My watertable is at best 6-8 inches below ground during the winter....my deck is 8 years old...still level and has lots of heavy large pots. I do believe we dug about 40" deep to put a fair amount of gravel we were worried about sinking. With the sonotube enough of the cement should stay in particularly with the 2 day method....when I build fences I just use dry quickcrete....plenty of water in the soil. mary

 

[NMbirds]

Yes, bridge pilings made of concrete are under water for years and on occasion that has created problems because of faulty concrete or construction but when done "properly" with sonotube and right mix, should not be a problem.
http://www.sonotube.com/products/tubebase_adv.html
I don't know anyone who has built a coop over a pond or a river but could be a novel idea with a platform run....might be a deterrent to most predators, like a moat around a castle.

 

[newchickmom]

I know Nothing about construction, but how about just setting your coop on cement blocks?