Any Advice Before Install

[YippeeSkippy]

Please, take pictures, share it with us so we can learn from this. Okay?

 

[duraleigh]

The poolcrete will crack whether with geogrid and rock or not. The good news is I don't believe it will matter. Is the poolcrete being laid on virgin soil?

 

[jkhamr]

The poolcrete will crack whether with geogrid and rock or not. The good news is I don't believe it will matter. Is the poolcrete being laid on virgin soil?

The pool crete will be placed on virgin soil. The pool has not been excavated yet, so I'm not sure what the sub soil consists of and without doing a fully engineered soils test, I won't know what the soil bearing capacity is. Before my neighborhood was developed, 30 years ago, it was a corn field. I know from my 36 years of experience in the construction industry that residential developments like mine are graded with whatever (cheap) soil the developer can find. It's also been my experience with foundations and basement concrete floors, 4"-8" of crushed rock is laid down before the conc. floor. We always use geogrid and crushed rock behind block retaining walls. Geogrid and crushed rock definitely stabilize the soil but I've had no experience with a pool bottom. Anyone who's been around construction knows concrete exists in only two states; 1) cracked, or 2) is going to crack. I know the pool crete will crack, I'm just trying to lessen the extent. I see several posts about pool bottom failures, there's always a better design out there and if it's never been done before, I don't mind guinea pigging my pool build to test it out.

 

[duraleigh]

I think you are in good shape. Virgin soil is the key. I used 2" of #57 rock as a base and my pool structure has been virtually motionless for the last 12 years. We replaced the liner last year and found several cracks in the poolcrete but nothing wider than a 1/16th.

 

[jkhamr]

I think you are in good shape. Virgin soil is the key. I used 2" of #57 rock as a base and my pool structure has been virtually motionless for the last 12 years. We replaced the liner last year and found several cracks in the poolcrete but nothing wider than a 1/16th.

Hey duraleigh, when you excavate a pool for 2" of rock and 2" pool crete, do you dig the additional 2" for the rock after the metal panels are set and the conc. collar is poured or do you set the panels on a 2" bed of rock? I have 4' metal panels and the pool crete is designed at 2" so the pool liner is 3'-10", the rock under the pool crete would raise the pool bottom to 3'-8" and would not be deep enough for the pool liner. Thanks.

 

[duraleigh]

my build was a little different than that. I poured a footing and set concrete block walls. the hole inside the footing was roughly3-4 inches below the footing height giving me enough room to use the rock and then bring the poolcrete level to the footing.

My liner was custom made to whatever height I wanted so it was forgiving.

 

[jkhamr]

my build was a little different than that. I poured a footing and set concrete block walls. the hole inside the footing was roughly3-4 inches below the footing height giving me enough room to use the rock and then bring the poolcrete level to the footing.

My liner was custom made to whatever height I wanted so it was forgiving.

Gotcha, I will probably go ahead and dig out the full 4", place the 2" layer of rock, and then set panels on top. I'll use a smaller rock on the shelf, that should make leveling the panels easier. Thanks for your input!

 

[jkhamr]

Just finished marking out the pool, hopefully by the end of tomorrow we'll have a hole in the ground.

 

[Texas Splash]

 

[kimkats]

Details!! We need details of what is being done and such stuff!

 

[Bperry]

For reference, the geogrid is used in retaining walls to couple the wall to the soil and make it harder for the wall to get pushed out of place. Anything happening under the pool is going to happen whether there’s geogrid or not.

 

[jkhamr]

For reference, the geogrid is used in retaining walls to couple the wall to the soil and make it harder for the wall to get pushed out of place. Anything happening under the pool is going to happen whether there’s geogrid or not.

I 100% agree that anything happening under the pool is goin to happen, so why not do something to help keep the results of whatever happens to a limited affect on the pool bottom. Geogrids are also used in steep slope applications to stabilize the grade. If the ground shifts or sinks, to some extent the geogrid and crushed rock will esentially widen the area of support for the pool floor no differently than a spread footing. The geogrid and rock will also act as a buffer between the grade and pool crete since materials expand and contract at different rates and proportions. In my location we go from 100+ degrees in the summer to negative teens in the winter. Also around here, you would never pour a concrete floor in a basement without a rock base first, I don't see the pool floor being any different. I'd much rather gamble $500 on my experience that tells me the geogrid and crushed rock base will help, rather than be one of the many posters on here wanting advice on how to repair their failed pool bottom.

 

[Bperry]

I 100% agree that anything happening under the pool is goin to happen, so why not do something to help keep the results of whatever happens to a limited affect on the pool bottom. Geogrids are also used in steep slope applications to stabilize the grade. If the ground shifts or sinks, to some extent the geogrid and crushed rock will esentially widen the area of support for the pool floor no differently than a spread footing. The geogrid and rock will also act as a buffer between the grade and pool crete since materials expand and contract at different rates and proportions. In my location we go from 100+ degrees in the summer to negative teens in the winter. Also around here, you would never pour a concrete floor in a basement without a rock base first, I don't see the pool floor being any different. I'd much rather gamble $500 on my experience that tells me the geogrid and crushed rock base will help, rather than be one of the many posters on here wanting advice on how to repair their failed pool bottom.

Don’t get me wrong, it’s your pool so you can do whatever you want. I’m just trying to understand what your goal with the geogrid is, not the rock. I don’t think either will hurt anything.

 

[jkhamr]

I'm thinking of two benefits, keep the excavated pool bottom safe from washing out between the time the hole is dug and the floor is poured and help prevent any major cracks in the floor after it's poured. The geogrid will hold the rock on the sloped surfaces until the floor is poured and as I said before it will spread out the load, so if the ground heaves or settles, the rock and geogrid will transfer that movement to a larger surface area, (hopefully) allowing the pool crete to flex instead of break.

 

[jkhamr]

Details!! We need details of what is being done and such stuff!

I think my profile pretty much lists everything going in.

 

[Mdragger88]

Keep the pics coming!

 

[kimkats]

OH MY! Look at that deep end!!! That is going to be SO fun to dive into!!!

 

[jkhamr]

We just got to the bottom of the hopper and hit ground water. No water coming in from the sides. It's not a big issue to over excavate, add 18" of rock to the bottom of the hopper and add a dewatering pipe, but has anyone installed a removable sump pump more permanently in the dewatering pipe? It would be like a basement sump pump, I'd just need to get a waterproof outlet box to the dewatering pipe location to plug in the sump pump. Maybe it'd be more hassle than just dropping a sump pump down the dewatering pipe, but I don't know how often or how fast the water will come in so a more permanent solution would be better and I could handle it now while it's early in the pool build. I was already planning on running drain tile around the pool at the height of the shallow end, from the high side of our yard to daylight at the low side of our yard, but that drain tile is 54" above the hopper depth and won't catch the ground water. I was installing the drain tile because the houses east of me go up hill and the houses west of me go down hill.... 1st pic is when we initially hit water, 2nd pic is next morning, it doubled in size but froze over night, might have gotten bigger if it didn't freeze.

 

[ajw22]

I would construct the well points so that you can have a sump pump with a float switch to keep the liner from floating if necessary. You don't know how much the underground water will be a problem once the pool is installed.

Well Points and Dealing with Groundwater

As anyone who has ever worked with dirt in the South knows, clay soil can present many problems in the construction process. In swimming pool building it can cause problems not easily rectified wit…

everclearbackyards.wordpress.com

 

[jkhamr]

I would construct the well points so that you can have a sump pump with a float switch to keep the liner from floating if necessary. You don't know how much the underground water will be a problem once the pool is installed.

Well Points and Dealing with Groundwater

As anyone who has ever worked with dirt in the South knows, clay soil can present many problems in the construction process. In swimming pool building it can cause problems not easily rectified wit…

everclearbackyards.wordpress.com

I believe we're on the same page. The water didn't show up until we hit the 8'-8" hopper depth, I've got the excavator taking out an extra 24" in the 6'x8' hopper. I'll place a ground water drain in the middle of that area, fill with rock, pipe the ground water drain to a large vertical pipe for a sump pump, the vertical pipe will be finished off at the concrete pool deck with a skimmer cover. I'm wanting to run a pvc pipe from the large vertical pipe under the concrete pool deck to a point at my wood deck where I have an outlet, then I could pulg in the sump pump there. Then I'd run another pvc under the concrete pool deck to daylight for the sump pump drain hose. I'm trying to set this up so I don't have a sump pump drain hose and power chord running across the top of the pool deck.

I'm also going to add a hydrostatic valve to one of my main drains. Is the valve sufficient or do I need a perforated pipe into the rock bed?