Re-backfilling pool, new decking will be installed (evenutally) two types of rock or one?

Aleforge

Well-known member
May 31, 2014
280
Wentzville, MO
I did a search and came up with various talk on back fill material. I even asked a similar question on sand vs gravel (gravel won), but I am curious on something I didn't ask / find.

I have to fill in around my pool sides and over the top of the new pipes that I ran. Then I will have to have concrete poured over the top for the new decking. Considering originally I had sand then a layer of larger rock I was curious if I needed to use two different fill substrates again, or if I can go with just one and pack it.

Thanks for the help!
 

Aleforge

Well-known member
May 31, 2014
280
Wentzville, MO
So just go with 100% 57 stone up to the concrete?

EDIT: I just talked to a local landscaping company and they told me 57 stone is what they consider 1" clean gravel. Looking at photos it seems fairly large, is that the correct sized rock for backfill?

Thanks for the help!
 
Last edited:

ajw22

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TFP Guide
Jul 21, 2013
18,959
Northern NJ
So just go with 100% 57 stone up to the concrete?

EDIT: I just talked to a local landscaping company and they told me 57 stone is what they consider 1" clean gravel. Looking at photos it seems fairly large, is that the correct sized rock for backfill?

Thanks for the help!
You can use a mix of these two in different areas.

There are different types and sizes or gravel:
  • 89 stone is a small size used as the base to set a pool on and to backfill the step and seating areas. 89 stone can fill tight areas that may leave a void area of material.
  • 57 stone is about a half inch in size and is used to backfill the side walls of a pool. 57 stone works well locking together for good compaction when it is dropped into the overdig area around the pool. Its 95% compacted out of the bucket. A light hand tamp or plate compactor and you are good.
 

Aleforge

Well-known member
May 31, 2014
280
Wentzville, MO
My back fill kind of consists of just the area about a foot below lip over PVC pipes. Not actually down the sides. It will be cheaper for me to go with the 57 (one delivery) would you feel comfortable personally filling over the pipes with it?

I appreciate the help!
 

jimmythegreek

TFP Expert
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In The Industry
Aug 10, 2017
2,634
Morris Cnty NJ
The one thing with 3/4 clean (57) is certain soils can migrate into the stone. Whenever I use it I wrap it in filter fabric or geotextile. Depends on decking going on after. If using pavers its best to use road base and compact it. Picture all the voids in the spaces of the clean gravel. Over time the native dirt can break down with rain and ground water and penetrate those voids with fines. You wont swell the stone nut you will slightly settle the native soil edge. Mind you I work in clay country and I plan for the worst my work is forever work. If you dont have a plate compactor you are better of with clean stone. 1" is too big you want 3/4 clean stone. What's the decking gonna be
 

Aleforge

Well-known member
May 31, 2014
280
Wentzville, MO
The one thing with 3/4 clean (57) is certain soils can migrate into the stone. Whenever I use it I wrap it in filter fabric or geotextile. Depends on decking going on after. If using pavers its best to use road base and compact it. Picture all the voids in the spaces of the clean gravel. Over time the native dirt can break down with rain and ground water and penetrate those voids with fines. You wont swell the stone nut you will slightly settle the native soil edge. Mind you I work in clay country and I plan for the worst my work is forever work. If you dont have a plate compactor you are better of with clean stone. 1" is too big you want 3/4 clean stone. What's the decking gonna be
I never saw this reply... =(

I actually am going to order the rock in the next day or so, I came back to this post to recheck what I needed. I will have concrete decking when it's all said and done. But that won't be until next season as I am tight on money. My wife is really pushing me get this done as my family wants to swim (opened pool already). But everyone refuses to jump in due to the pool sitting in the middle of a mud pit. And well the wasps love the mud so I get it.

Anyways I was going to order 3/4" clean gravel as I thought stone and gravel meant the same thing. Are they actually different? I don't own a tamper but they aren't expensive so if it's best to tamp I will do so. I was thinking about some landscaping fabric prior due to weed control on the shallow area around the trench. I just noticed that you mentioned it.

Thanks for the help!
 

jimmythegreek

TFP Expert
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In The Industry
Aug 10, 2017
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Morris Cnty NJ
If you dont have a plate compactor stick with 3/4 clean stone. It self compacts. I use small rolls of astroturf on top of stone for builds in progress to keep homeowners happy when pool is full of water
 

Aleforge

Well-known member
May 31, 2014
280
Wentzville, MO
I keep trying to find "3/4 clean" but my local places keep pricing me on 1" clean when I ask. I am not sure really what to do... =/

I would pick up a plate compactor if that would make using 1" OK though.
 

jimmythegreek

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In The Industry
Aug 10, 2017
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Morris Cnty NJ
Every stone yard has three quarter clean. Sometimes called 57 stone, sometimes drain stone. Just make sure its jagged rock and no small stuff or fines mixed in. 1" would work but leaves larger voids that soil can migrate into. No need to plate. compact clean stone it barely moves its 90% proctors density out of the bucket
 

Aleforge

Well-known member
May 31, 2014
280
Wentzville, MO
Hi Jimmy,

I ended up going with 1" clean and the rocks are fairly jagged. I didn't notice any mixed in small pieces at all. I did notice it compacted very quickly after just walking around on it. So much so that I could roll the cart with 1k lb worth of rock in it without leaving tire tracks. I will say I was a bit "surprised" on how much 8 cu/yd of rock was (lol). I have never gotten that much of anything dumped off. SOMEHOW I managed to move it all solo with just a shovel and a cart but it took me around 25 hours in 95 degree heat. Lots of breaks though but it was one of the most daunting things I have ever done.

I appreciate all of the help!
 

jimmythegreek

TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
2,634
Morris Cnty NJ
You should be good to go. If you have a hand tamper it wouldn't hirt to tamp it amd make sure its packed tight. Normally in a trench it self compacts as it's free to flow, with a pool there is bracing and pipes etc. That can hang up the stone and leave a tiny bit of room.
 

Aleforge

Well-known member
May 31, 2014
280
Wentzville, MO
Thanks for the tip and help! I won't be pouring until next year, mostly due to replacing all the pipes myself. I figured if there is a leak it would be much easier to dig out rock than break up concrete lol. It's actually looks a lot better now that the mud swamp around it is gone.