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Below grade concrete engineering help

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DejaVoodoo

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Dec 9, 2009, 9:37:41 PM12/9/09
to markk...@hotmail.com
Hi everyone. I am trying to work through plans of a 12x16 ft
greenhouse. It will have a concrete foundation pored, but here is the
tricky bit. I need a 10x4x3 sump chamber below the foundation. I
live near houston and we have a very high water table. The concrete
sump must be water tight (will contain fish). The foundation will be
poored 1 foot below grade. That puts the bottom of the sump 4 feet
below grade. Don't ask why or suggest alternatives, I really just
need help making this design work.

My thoughts are to dig the sump, poor the 10x4 foundation. Build
forms for the sump walls and pore them all in one go.

When pooring the actual greenhouse floo,r poor on top of the sump such
that there will be a 10x4 hole in the floor looking down into a 3 foot
concrete hole

Block walls will be built up from there and water proofed. When done,
it should resumble a pond in a greenhouse.

The floor when complete will contain (if I did my math right) up to 13
tons of gravel and water.

My concerns are the stress between sump and floor and potention for
cracking.

Questions:
How thick do I need to make my lower and upper foundations.
How thick do I need to make the walls of the sump.

My gueses are with enough rebar 8 inch foundations and 6 inch walls.
I just really do not want the sump to "break off".

I also assume if I do this myself it will take quite a bit of time and
I'll have to be concerned about it floating up out of the gound like
an empty pool. The only thing I can think of is to leave an open
drain and let it flood if needed. Once the sump is rendered and water
proof, it can be permantly flooded.

Thanks for any help!
Mark

PS
And for those that cannot help but ask, this is part of a larger
aquaponics system.

RicodJour

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Dec 9, 2009, 11:15:50 PM12/9/09
to
On Dec 9, 9:37 pm, DejaVoodoo <markkana...@hotmail.com> wrote:
> Hi everyone.  I am trying to work through plans of a 12x16 ft
> greenhouse.  It will have a concrete foundation pored, but here is the
> tricky bit.  I need a 10x4x3 sump chamber below the foundation.  I
> live near houston and we have a very high water table.  The concrete
> sump must be water tight (will contain fish).  The foundation will be
> poored 1 foot below grade.  That puts the bottom of the sump 4 feet
> below grade.  Don't ask why or suggest alternatives, I really just
> need help making this design work.

Without asking why _and_ suggesting alternatives, people won't be able
to help you and your design won't work. It's clear from what you've
written that you don't know enough about concrete construction to tell
a good answer from a bad answer, and you're asking a bunch of random
people on Usenet for help. This is not a good way to proceed.

R

DanG

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Dec 10, 2009, 5:59:29 AM12/10/09
to
Concrete does not lend itself to a monolithic pour like you
describe. The right angle intersections at the bottom and top of
the pond walls are very subject to cracking. These conditions are
usually better dealt with by deliberate sealable joints or various
waterproof seals a bit like these:
http://www.greenstreak.com/div3/Waterstops/pvc.asp

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
dgri...@7cox.net

"DejaVoodoo" <markk...@hotmail.com> wrote in message
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ransley

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Dec 10, 2009, 7:14:13 AM12/10/09
to

I wont ask why, but you dont need a sump or a tank or fish, its a
greenhouse for plants with a floor made to drain water , its not
carpeted. I have one also, it leaks from above and I dont care at all.

jloomis

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Dec 10, 2009, 9:14:26 AM12/10/09
to
Separate the pours.
I believe that is what you have planned.....
Expect some expansion and contraction between floor and sump.
This would be better than having a crack form @ sump and floor.
Sump would be height of floor....curb of sump.
Also a pond membrane could be used in the sump.
My question is:
If it is a sump watertight as origninally planned where would water come
from.
(watering greenhouse?)
Anyway, I have poured "hot tubs" and the use of steel would be important in
the pour.
A vibrator also to make sure voids are handled properly.
I imagine you are planning drains and filtering piping in the sump.
Sounds interesting....
I have a large concrete foundation greenhouse although no sump. Walls are
10" and about 6' tall on 3 sides to contain heat........heat sink.
no pond though.
jloomis

"DejaVoodoo" <markk...@hotmail.com> wrote in message
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John Grabowski

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Dec 10, 2009, 5:29:23 PM12/10/09
to

"DejaVoodoo" <markk...@hotmail.com> wrote in message
news:21b51dd8-e7c2-467a...@z41g2000yqz.googlegroups.com...


*I'm not an expert on this, but a thought did occur to me. Why not have the
sump prefabricated by a concrete casting company? Then you can seal it on
the outside and just drop it in the hole and pour concrete around it.

v8z

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Dec 11, 2009, 12:29:25 PM12/11/09
to
"John Grabowski" <jgra...@optonline.net> wrote in message
news:4b217653$0$22504$607e...@cv.net...
If you are a bit flexible in the shape/size, make some phone calls and
you'll probably find a concrete place that has pre-cast box cheaper than
contracting a custom one - i.e. burial vault, drainage box, septic boxes,
etc., etc.


DejaVoodoo

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Dec 11, 2009, 12:40:55 PM12/11/09
to
On Dec 10, 4:29 pm, "John Grabowski" <jgrabo...@optonline.net> wrote:
> "DejaVoodoo" <markkana...@hotmail.com> wrote in message

>
> news:21b51dd8-e7c2-467a...@z41g2000yqz.googlegroups.com...
>
>
>
>
>
> > Hi everyone.  I am trying to work through plans of a 12x16 ft
> > greenhouse.  It will have aconcretefoundation pored, but here is the
> > tricky bit.  I need a 10x4x3 sump chamberbelowthe foundation.  I

> > live near houston and we have a very high water table.  Theconcrete
> > sump must be water tight (will contain fish).  The foundation will be
> > poored 1 footbelowgrade.  That puts the bottom of the sump 4 feet
> >belowgrade.  Don't ask why or suggest alternatives, I really just
> > needhelpmaking this design work.

>
> > My thoughts are to dig the sump, poor the 10x4 foundation.  Build
> > forms for the sump walls and pore them all in one go.
>
> > When pooring the actual greenhouse floo,r poor on top of the sump such
> > that there will be a 10x4 hole in the floor looking down into a 3 foot
> >concretehole
>
> > Block walls will be built up from there and water proofed.  When done,
> > it should resumble a pond in a greenhouse.
>
> > The floor when complete will contain (if I did my math right) up to 13
> > tons of gravel and water.
>
> > My concerns are the stress between sump and floor and potention for
> > cracking.
>
> > Questions:
> > How thick do I need to make my lower and upper foundations.
> > How thick do I need to make the walls of the sump.
>
> > My gueses are with enough rebar 8 inch foundations and 6 inch walls.
> > I just really do not want the sump to "break off".
>
> > I also assume if I do this myself it will take quite a bit of time and
> > I'll have to be concerned about it floating up out of the gound like
> > an empty pool.  The only thing I can think of is to leave an open
> > drain and let it flood if needed.  Once the sump is rendered and water
> > proof, it can be permantly flooded.
>
> > Thanks for anyhelp!
> > Mark
>
> > PS
> > And for those that cannothelpbut ask, this is part of a larger

> > aquaponics system.
>
> *I'm not an expert on this, but a thought did occur to me.  Why not have the
> sump prefabricated by aconcretecasting company?  Then you can seal it on
> the outside and just drop it in the hole and pourconcretearound it.- Hide quoted text -
>
> - Show quoted text -

I thought of that but was having trouble finding anyone who does it.

John Grabowski

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Dec 11, 2009, 2:56:16 PM12/11/09
to

DejaVoodoo

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Dec 12, 2009, 9:34:04 AM12/12/09
to
I had the same thought, been looking around for place that sells
precast concrete boxes. Have not had a lot of luck so far. I would
go with a fibroglass or plastic sump, but tree roots are a big
concern. Concrete bocks would be my prefered method of construction.
I'm leaning tward that now, with a couple inches of fibromix to seal
it up. There are so many methods of pond construction out there, it
is hard to determine what is best for me.

Thanks
Mark

PeterD

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Dec 12, 2009, 3:26:47 PM12/12/09
to
On Sat, 12 Dec 2009 06:34:04 -0800 (PST), DejaVoodoo
<markk...@hotmail.com> wrote:

>I had the same thought, been looking around for place that sells
>precast concrete boxes. Have not had a lot of luck so far.

One would think in Texas there have to be many! Around here (New
England) most larger towns have at least one place.

> I would
>go with a fibroglass or plastic sump, but tree roots are a big

>concern. \

Why? Roots are not likely to penetrate plastic unless they 'know'
there is water there.

>Concrete bocks would be my prefered method of construction.

Ug... I personaly would not do that.

>I'm leaning tward that now, with a couple inches of fibromix to seal
>it up. There are so many methods of pond construction out there, it
>is hard to determine what is best for me.

Talk to some place that makes swimming pools and ponds.

>
>Thanks
>Mark

Tom Cular

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Dec 13, 2009, 4:21:48 PM12/13/09
to

"DejaVoodoo" <markk...@hotmail.com> wrote in message
news:4c2f9d84-7250-48c6...@d10g2000yqh.googlegroups.com...

>I had the same thought, been looking around for place that sells
> precast concrete boxes. " Snip "
> Thanks
> Mark

I found 35 precasters in the Houston area, follow this link to The Blue
Book. http://www.thebluebook.com/ Select your area, then under Keywords
,type concrete, then follow down the list until you find conctete- precast.

Tom

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