I tore down a 18’ X 48” AGP with a 18”-24” depressed center. I want to replace it with a 54” pool without a depressed center, so I must fill in the depression. I can’t seem to find any info on this. All of the instructional material just says never fill below an AGP. In the construction world this is done all of the time. I’m thinking screenings, tamped with a vibrating plate or a “Jumping Jack”, one of those powered tampers. Any advice?
Replacing AGP, Must fill depresses center…How?
- Thread starter KOG
- Start date
Decoy205
Silver Supporter
My 21’ pool had a deep section. I had a new pool installed this summer. The installer used the bobcat to pull dirt in from the sides before adding sand and the gorilla pad. I asked him if there would be any issues he said the vehicle weighed so much it will be compacted and won’t go anywhere.
If you do this with a plate compactor you should probably give it extra time to see if there is any settling.
If you do this with a plate compactor you should probably give it extra time to see if there is any settling.
Decoy205
Silver Supporter
If it were me, I would use 1/4" minus rock, plate compact, then the typical mason sand on top. 1/4 minus goes by many names: chat, crushed run. It is fine crushed gravel with the fines mixed in (almost like a dust). It compacts very well and doest settle if compacted properly.
Your new liner can stretch quite a good deal so close is probably close enough if there is some settling after you compact everything.
Now. If a paver(s) under a leg drops an inch, that could be an entirely different outcome.
Now. If a paver(s) under a leg drops an inch, that could be an entirely different outcome.
1) The center of the pool is not really where it is critical, it is around the perimeter
2) Any contractor that tells you "the machine is heavy enough to compact it" needs to go. I have had a number of contractors that said things like that ended up removed from the site.
3) A jumping jack is a toy - used only for trenches where it is the only thing that fits
4) A plate compactor that a normal homeowner can rent and move around in their SUV is a bigger toy
5) If your fill is at the wrong moisture content, you can compact it with the biggest thing you can find, and when it gets to the right moisture content it will still settle. Compaction is about understanding and knowing the compaction curves of the particular soil you are working with - not how hard you can hit it.
6) 3/4" minus or 1" minus (not 1/4" minus) is extremely forgiving when it come to moisture content (it has a very flat Proctor curve). It goes by a load of different names across the country - Quarry Process, QP, Crusher Run, Pack, DGA, Dense Graded Aggregate, Shoulder Stone, and there are a bunch of DOT specifications for it that cost more because they are very specific. It is also a bear to shovel by hand. 1/4" minus is normally used as paver base, 3/4" or 1" minus is road base and fill.
For the OP, you should be OK with any clean fill in the center area. I would go with QP. Install it in 6" lifts, and compact it with as large a plate as you can manage to rent. If there is any settling the liner will stretch to accommodate it. Do not use topsoil, other organic fill, and I would stay away from any sort of expansive soils (clearly).
2) Any contractor that tells you "the machine is heavy enough to compact it" needs to go. I have had a number of contractors that said things like that ended up removed from the site.
3) A jumping jack is a toy - used only for trenches where it is the only thing that fits
4) A plate compactor that a normal homeowner can rent and move around in their SUV is a bigger toy
5) If your fill is at the wrong moisture content, you can compact it with the biggest thing you can find, and when it gets to the right moisture content it will still settle. Compaction is about understanding and knowing the compaction curves of the particular soil you are working with - not how hard you can hit it.
6) 3/4" minus or 1" minus (not 1/4" minus) is extremely forgiving when it come to moisture content (it has a very flat Proctor curve). It goes by a load of different names across the country - Quarry Process, QP, Crusher Run, Pack, DGA, Dense Graded Aggregate, Shoulder Stone, and there are a bunch of DOT specifications for it that cost more because they are very specific. It is also a bear to shovel by hand. 1/4" minus is normally used as paver base, 3/4" or 1" minus is road base and fill.
For the OP, you should be OK with any clean fill in the center area. I would go with QP. Install it in 6" lifts, and compact it with as large a plate as you can manage to rent. If there is any settling the liner will stretch to accommodate it. Do not use topsoil, other organic fill, and I would stay away from any sort of expansive soils (clearly).
Decoy205
Silver Supporter
I believe my PB has had experience with the soils in my area and specifically what soil I had and also knew the perimeter of the pool was the key.
I believe in my case he was basically saying the machine was be the “plate compactor” . I do not claim to be an expert just simply that I had the same concern and that was my experience.
That does not fly. Soils don't work that way. Compaction does not work that way. Machine loading does not work that way - in fact track loaders are specifically designed to MINIMIZE ground pressure.
I don't do this work any more, but I did do it for quite some time. A Masters in Civil Engineering with concentrations in Construction Engineering Management and Ground Modification. Used to work for a Geotechnical Engineering Company as a field engineer doing among other things, inspection of fill placement.
Decoy205
Silver Supporter
I think you’ll be good with your pool. I’m going with “screenings” as we call them around here. I think it’s the same as “1/4 minus” meaning it’s everything 1/4” and smaller, I think. It kinda turns to concrete after a while. And compact with vibratory plate compactor. I think that’s best I can do.