DIG DAY - few soil/dig issues - any expert thoughts out there welcomed

Riddler0520

Well-known member
Jul 26, 2020
160
Charlotte, NC
Pool Size
23000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Be sure to have a conversation with the PB about proper compaction of all the backfill material. That site material can not be properly compacted to put your deck on. You now have some very deep fills which most gunnite pool installs do not have. You will need a good granular material compacted in lifts or clean stone (which does not require compaction) as he used below the pool. Driving over the material or letting it settle over time are not acceptable compaction methods an will lead to settling material.

Just to clarify - prior you had suggested a gravity drain to empty to adjacent creek at lower grade - you mentioned below a wick drain which I believe is more complex

Is a gravity drain the solution you would recommend as I believe that’s where a catch basin under the pool base/low point (buried in gravel ??) Catches the water and runs it to creek

Probably should have done that prior to rebar 🤦🏻‍♂️
 

Rich D

Bronze Supporter
Aug 3, 2018
961
MA
When you say fills - I presume you mean the open space behind the walls where they excavated some extra soul away and needs fill ? What would be your preferred method of compaction ?

Correct, the compaction needs to be done with a heavy compactor. Typically those are rated to compact a 12" lift of the proper material at the correct moisture level. The material should be placed at a 12" maximum depth then leveled and if things are very dry and dusty it should be watered and let soak in, then at a very minimum 2 passes with the compactor ( I always go at least 3) . The other alternative is to use the clean stone like they did under the floor, that does not require compaction. This is more expensive however you do not need to worry about your contractor using correct compaction techniques (most do not).

Is there anything I need to ask them about what they did with rebar

If you were given details on the Size and spacing in your contract them be sure to check that. This is supposed to be checked by the local building inspector, However building inspectors come in all different shapes and sizes, some are knowledgeable and dedicated to there profession and some are not..

Do make sure there will be a minimum of 3" concrete around the rebar. It needs to be held off the forms and bottom that minimum amount.

Just to clarify - prior you had suggested a gravity drain to empty to adjacent creek at lower grade - you mentioned below a wick drain which I believe is more complex

Sorry for the confusion. They are the same. The gravity drain I described is also called a wick drain.

Is a gravity drain the solution you would recommend as I believe that’s where a catch basin under the pool base/low point (buried in gravel ??) Catches the water and runs it to creek

A catch basin is a structure used to "Catch" surface water and put it into a drainage pipe. So you would not be putting a catch basin in the gravity drain I described. A "sump" is a vertical structure (usually just a large diameter pipe ) that is used to gain access to the ground water table so you can monitor its level and install a pump when necessary to lower the ground water. These sumps can have drain lines that collect the ground water going into them and / or outfall drain lines that go to daylight to drain the ground water.

Probably should have done that prior to rebar 🤦🏻‍♂️

correct.. All is not lost. You can still dig down to the very edge of the pool bottom and expose the stone stone he placed under it. You should be fairly wide when you get close to the pool bottom and as close as he can get without undermining the pool and start your drain there with plenty of stone around the beginning of the first 10' of perferated pipe.

Post back with the elevations of bottom of pool and creek bed if you decide to install the drainage.
 

Riddler0520

Well-known member
Jul 26, 2020
160
Charlotte, NC
Pool Size
23000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Correct, the compaction needs to be done with a heavy compactor. Typically those are rated to compact a 12" lift of the proper material at the correct moisture level. The material should be placed at a 12" maximum depth then leveled and if things are very dry and dusty it should be watered and let soak in, then at a very minimum 2 passes with the compactor ( I always go at least 3) . The other alternative is to use the clean stone like they did under the floor, that does not require compaction. This is more expensive however you do not need to worry about your contractor using correct compaction techniques (most do not).



If you were given details on the Size and spacing in your contract them be sure to check that. This is supposed to be checked by the local building inspector, However building inspectors come in all different shapes and sizes, some are knowledgeable and dedicated to there profession and some are not..

Do make sure there will be a minimum of 3" concrete around the rebar. It needs to be held off the forms and bottom that minimum amount.



Sorry for the confusion. They are the same. The gravity drain I described is also called a wick drain.



A catch basin is a structure used to "Catch" surface water and put it into a drainage pipe. So you would not be putting a catch basin in the gravity drain I described. A "sump" is a vertical structure (usually just a large diameter pipe ) that is used to gain access to the ground water table so you can monitor its level and install a pump when necessary to lower the ground water. These sumps can have drain lines that collect the ground water going into them and / or outfall drain lines that go to daylight to drain the ground water.



correct.. All is not lost. You can still dig down to the very edge of the pool bottom and expose the stone stone he placed under it. You should be fairly wide when you get close to the pool bottom and as close as he can get without undermining the pool and start your drain there with plenty of stone around the beginning of the first 10' of perferated pipe.

Post back with the elevations of bottom of pool and creek bed if you decide to install the drainage.

PB confirmed he is installing a gravity drain beneath the pool/deep end

Also, he said he is shooting the deck and walls with Gunite at 10”-12” thick, does that sound good to you - a lot of what I’ve read says minimum of 6”-8” so what he states seems good 🤷‍♂️

I am in rapid fire learning mode as I’ve owned pools prior but never paid attention to the science of things - kind of forced too when you build.

We are installing 2 skimmers, 3 returns/2 bubblers and what looks like 4 drains ??

The drains at the bottom is what I’m confused about - plan to do a walk through having him explain things prior to shooting

Did confirm PVC is 2”

Also, in SPA we should have a return for a dedicated water feature pump to help create that water sheen look we are going for seeing it is a 5’-6’ft wide spillover

What am I looking for to confirm - just curious prior to PB coming back next week

Thoughts ?
 

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Rich D

Bronze Supporter
Aug 3, 2018
961
MA
PB confirmed he is installing a gravity drain beneath the pool/deep end
Great news.. Your PB sounds like one of the good ones. You should get the details on how the drain is built so you fully understand how it will work. 2 critical items is the entire run of the drain from pool to outfall should be encased in clean stone and the stone should be wrapped in filter fabric. You also might want to incorporate putting a additional pipe in the same trench for your surface water drainage. This would most likely go on top of the gravity wick drain and should have at least a 1% pitch minimum.
 

Riddler0520

Well-known member
Jul 26, 2020
160
Charlotte, NC
Pool Size
23000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
Be sure to have a conversation with the PB about proper compaction of all the backfill material. That site material can not be properly compacted to put your deck on. You now have some very deep fills which most gunnite pool installs do not have. You will need a good granular material compacted in lifts or clean stone (which does not require compaction) as he used below the pool. Driving over the material or letting it settle over time are not acceptable compaction methods an will lead to settling material.
Rich,
7 days post Gunite shoot

Have been keeping shell watered while we wait next steps....

PB coming over so we can talk through the water management system - i.e. all the drainage around the perimeter pool and back wall as well as backfill...I know he did mention the use of gravel for backfill
Question: you saw how deep/tall the wall swells are, does the entire area behind the walls need to be filled with gravel or only up to a certain depth ?

We’ve got lots of water in the pool (3 ft) but there is a hole in the deep end where they had a pump but have since removed...PB said he actually wanted the water in the shell for curing and keeping water weight in the shell due to higher table.

He said he made the floor and walls A minimum of 8”-10” thick as the to[ bond beam area looks 10”-12” but no way to verify true thickness of floor/walls....I know I asked him like 20 times about the water in the soil Nd the fact the soil in the deep was that grey mushy stuff (like years and years of saturated clay) low spot in yard
I could tell he was getting frustrated with me asking the same questions over and over....he said that is why he over dug 2-3X ft and brought in gravel and built up the floor like a ft or more of gravel for a solid base.....Plus he said he made the floor and walls thicker with Gunite

I have to trust as I can’t be out there every minute plus I am no expert in this

Which is why next phase is water management as we clearly have lots of water around the pool if it has 2-3ft of water inside the pool now - I know we have tile and coping up next as well
 

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Rich D

Bronze Supporter
Aug 3, 2018
961
MA
...I know he did mention the use of gravel for backfill
Question: you saw how deep/tall the wall swells are, does the entire area behind the walls need to be filled with gravel or only up to a certain depth ?

You want the gravel under any parts of the deck and at least 2' wider than the deck for support. The gravel should come all the way up to just under the deck. I am not a fan of that coil pipe they are using for the drainage. It can get crushed and you can not seal the joints so there is a possibility of root intrusion which will cause blockages. A blockage in that type of pipe can not be cleared by a snake or water jet like solid sdr35 ot scdl 40 can be. I would insist on 6" sdr for you wick drain. Try to get exact details on how he will install the wick drain. He should dig down the deep end of the pool and get at least 1 ' below the bottom of pool and into as much of the stone down there as possible. A little undermining of the pool shell will be ok because he will be replacing with stone that can be tamped back under the pool shell. A little pitch on the pipe would be nice but if required it can be layed flat and will work just as well. The first 10' should be perferated to allow water into the pipe, the rest can be solid. It is critical that the entire pipe run is encased in stone (4"under and 12" sides and top(the more the better)) and the stone is fully wrapped in a good quality filter fabric.
 
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Riddler0520

Well-known member
Jul 26, 2020
160
Charlotte, NC
Pool Size
23000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
You want the gravel under any parts of the deck and at least 2' wider than the deck for support. The gravel should come all the way up to just under the deck. I am not a fan of that coil pipe they are using for the drainage. It can get crushed and you can not seal the joints so there is a possibility of root intrusion which will cause blockages. A blockage in that type of pipe can not be cleared by a snake or water jet like solid sdr35 ot scdl 40 can be. I would insist on 6" sdr for you wick drain. Try to get exact details on how he will install the wick drain. He should dig down the deep end of the pool and get at least 1 ' below the bottom of pool and into as much of the stone down there as possible. A little undermining of the pool shell will be ok because he will be replacing with stone that can be tamped back under the pool shell. A little pitch on the pipe would be nice but if required it can be layed flat and will work just as well. The first 10' should be perferated to allow water into the pipe, the rest can be solid. It is critical that the entire pipe run is encased in stone (4"under and 12" sides and top(the more the better)) and the stone is fully wrapped in a good quality filter fabric.
I am waiting for PB to come over to discuss - that flex tube there he connected to the downspout under the retaining wall when they shot it so it didn’t flood out the area - really not sure his exact plans but want him to walk me through exactly what we are doing

The backside top and right sides of pool behind won’t have decking (image). I am fine with grass up to the retaining wall as it is far removed from pool (clippings) but the area behind I plan to fill and have a few feet wide decorative stone butting up to rear grass yard so they aren’t throwing clippings into the pool

For behind the pool; that’s obviously where the water is pooling collecting all the runoff from higher elevation - knowing that no decking is behind the pool any thoughts on how much gravel vs dirt vs the stone for top layer to use ?

You can see from the image the Travertine deck will be placed in front of the pool, the stairs leading to Baja shelf entry and spa (in front of retaining wall) and will wrap around somewhat on the left side

I imagine this area isn’t super wet but definitely plan to have him run the drainage around the left side seeing we excavated that area already and will ensure all of that material is 100% gravel for the deck base (I know he mentioned something about ABC compacted, not sure what that is)

My thought for the main drainage concern is likely the area behind the pool as the water makes its way downhill and under.

Appreciate yourself guidance - helps me ask informed questions of PB during our meet ups

First regret too - we only installed 6 spa jets where I think we should have had 7 or 8 due to the oversize - maybe it won’t be bad once full 🤷‍♂️
 

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