Pool in pool...

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davelinde

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Sep 18, 2012
391
Lake Nona, Florida
We are subbing out construction of our pool and the first guy hired was to do demolition of a knee wall and footer that's in the way. When he got into it he confirmed what we suspected... that the knee wall was built on top of an old pool that was tipped in on itself and backfilled. So... the new pool will end up built inside the old pool. The demo guy said that the best way to do this would be to excavate out a rough opening and pull out all the concrete... then he would backfill the hole so the pool layout guy could mark the excavation and let our pool excavator cut the precise hole.

We talked to our excavator and he said that was for sure the cheapest way to go - if he hit any concrete in the excavation his charges go up. The demolition guy quoted us a fixed price to bust up and pull out any remnants of the old pool and backfill.

Anything I should be concerned about here?
 
I am not a pool contractor, but I do build houses for a living..
I would never build anything over an existing foundation/footing
I would have your excavator sub remove all debris and footings down to what we refer to as undisturbed earth.
Then let the pool contractor take a look and let you know if the hole is big enough and if you need to backfill to get to the right elevation(s) for the new pool design.
If you have to add back fill, use only structural fill sand in 6" "lifts" (lifts refer to 6" of fill at a time and compact each "lift" before adding the next lift.
It never hurts to have a soils engineer to test the soils to make sure they can withstand the pressures.
Generally, the soils engineer would test the bottom of the excavation, then test the lifts as they go along. If your excavator sub is experienced in structural backfilling, you could get away with the initial test and then test it again after the last "lift"

Just my two cents

Cush Dobbs
 
Thanks for the quick feedback. This is consistent with what everyone is telling me too. The demolition guy said he's done this before and the key is to get the debris out and taken away, then backfill correctly - then let the pool excavator start on it know there's nothing to hit.

They are digging as I type. I'll be checking on the "lifts" business. I did not know about that, but it makes sense.
 
Update... demolition guys found the outline and floor of the old pool smack in the middle of where we want to put ours. They are coming back with jackhammers tomorrow and will remove the part that's in our layout area. Then they will backfill and compact so the pool excavator can layout and dig again...

First cost over-run. Cha-ching.
 
You are starting at the same time of year I did mine last year.
Be sure to read all you can on this website, especially the Pool School, as the information will help you make good decisions
Good luck and don't forget to ask any questions about anything
If your getting a robot pool vac, consider getting extra large main drain covers as the robots get stuck on normal drain covers
What kind of pool will you be building?
How deep is your water table?
What type of equipment are you considering?
What will you do for a pool deck?
Consider installing a hard waste line out to some good location away from your pool. That way when you have to remove water for watever reason, it will be a cinch
The pool contractors are generall ....ehhhh, not too bright about drainage issues around the pool. They will be sure to get posotive drainage away from the pool with no conisderation as to where all that water will accumulate so make em consider everything.
 
cood60 said:
You are starting at the same time of year I did mine last year.
Be sure to read all you can on this website, especially the Pool School, as the information will help you make good decisions
Good luck and don't forget to ask any questions about anything
If your getting a robot pool vac, consider getting extra large main drain covers as the robots get stuck on normal drain covers
What kind of pool will you be building?
How deep is your water table?
What type of equipment are you considering?
What will you do for a pool deck?
Consider installing a hard waste line out to some good location away from your pool. That way when you have to remove water for watever reason, it will be a cinch
The pool contractors are generall ....ehhhh, not too bright about drainage issues around the pool. They will be sure to get posotive drainage away from the pool with no conisderation as to where all that water will accumulate so make em consider everything.
Click to expand...

Yes... but I bet FL is better for November/December construction than VA.

My wife has been studying this site - she is the expert.

We are getting a robot. I'll tell wife about drain covers.

We are down about 6' now and have not hit it yet... but I'm told our water table is pretty high.

Wife has the equipment list done already - no clue what's on it. Variable speed pump and Salt Water Chlorine... other stuff I'm sure.

Pavers.

Our plumber mentioned a hard waste line, we are having some irrigation work done too and I was going to have them trench something while they are laying pipe anyway. But I'm stumped where to send it... If I put it to the property line fence the water will run along the fence line and to the road - but it will go on my neighbors trees... will it kill them? I do not want to upset him, he's a nice guy.

I was going to talk to the layout guy about grades and drainage... I would have thought that was high on his list for layout? Guess not... drainage will be discussed for sure and planned.

THANKS!
 
Ahh, Florida
If water table has any chance of being near the bottom of the deep end, make sure they install a bunch of gravel in the deep end with a well point and a pipe coming up to the pool deck so you can pump it down if necessary. I am sure they will know about all that...but make sure they talk to you about it.

cush
 
The old pool is now out of the way. That was a monumental task (the stack of debris in the picture is about 20% of what they busted up and pulled out). The first night the floor was partially gone the excavation filled with water at about 7' down, so the water table is high I'd say. They pumped it out and finished last night late. We don't have enough fill left to get the hole near grade again. Next we find out if there's enough there to do layout and excavate back to where the new pool will be, if not it seems like we will be buying dirt to backfill, then hauling it away after we excavate (and paying for it in both directions).

[attachment=0:2fd4iix4]poolgone.JPG[/attachment:2fd4iix4]
 

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quick question... if we do end up needing more fill for layout - can anyone think of a reason I shouldn't just dig a pit behind the pool, fill it with concrete debris and use that dirt to fill? As long as I bury it a few feet down the grass should not know it's there? Just trying to think of options here.
 
If the fill is for layout purposes, it is fine to use anything...but it is not fine to use if the pool bottom will sit on the random fill.
I would never bury the concrete on my site as you may be sorry some day when you want to do something in that area. And it only costs a little more to haul it off, just cost to haul as most localities have places that take concrete for free as they recycle it
How deep will the new pool be and what shape etc.
 
As I posted, the guy who is going to layout,dig and steel this inspected and he is OK with it as is. I don't need to dream up anything now and the concrete will all be hauled off to recycling.

The pool guy said he would have done this all for us too and with bigger equipment he said he'd have been done by now. So we asked how much it would have cost... he quoted us more than triple what my demolition guy got. It pays to shop!

The pool is in 3 tiers, a sun shelf at 9", then a shallow end at 3 1/2' going to the deep end at 5'. Unfortunately our deep end is where the shallow end of the old pool was and vice-versa and a wall of the old pool was in the middle of our sun shelf. It's all out now and done.
 
Swampwoman said:
^on that note, it can also be tied to your pool plumbing so that you can just close off the other valves, and pump it out via waste line. Convenient for times of heavy rains. That's how mine is rigged.
Click to expand...

I double checked our quotes and a wellpoint is explicitly listed as part of the dig and steel work. I checked with our plumber about tying it into the well pump and he said he'd never heard of that. Actually he called it a "wonderful thing"... but said he'd never seen it done in central FL. His primary biz is renovation, so he drains a lot of pools.

I'm curious... for times of heavy rain do you actually try to pump down your water table? I guess I know how that works in basement sumps, but in this application is seems you could be pumping a long time?

In any case... we are moving along! Layout and dig should be next week, with steel and gunite to follow. I'll start another thread for our build progress since with the old pool gone we are no longer building pool in pool.
 
Hi there. We only pump out any collected water if there's more than six inches of rain over a few days, or in spring if there's a fast snowmelt, although the pool guys who close for me also run it at closing. My pool is at the bottom of a terrace and used to be a storm water catch basin - hence the extra measures.

I looked around online last year when we bought the place to learn a little more about it and found a builder's
website out in NJ who talks about doing it that way. I also read that some people put an auto pump down in the well, but they burn out as soon as a malfunction causes it to run dry. Which is why this "just-in-case" but convenient method makes sense to me ;)

Good luck on your build!
 
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