Overdig backfill compaction.

[SPman]

16x34 free form concrete wall vinyl pool

PB is backfilling with the soil from the excavation. They say they don't compact in stages, it will be one shot 48" deep. I'm speechless. This is not common right?

 

[MWengineer]

I can't say wether it is common with pools or not, but I would also be very concerned.
Placing then compacting in lifts, with proper soil moisture content, is the only way to get the soil to not noticibly settle down the road. I would imagine there is some piping in this excavation too? Settlement can downdrag the pipe causing stress and breakage. Any finishes placed on grade could crack or displace if not capable of spanning over the area. The criticality does vary somewhat with the soil type (sand better than clay), but I've still not seen a material that did not densify some in my 6 years of civil engineering.
That said, you can overdo compaction against a wall, and there is additional concern in that regard if the concrete has not yet reached it's design strength.

 

[jimmythegreek]

As stated different material needs different thickness and that depends on whether using a plate compactor or a jumping Jack. The latter is preferred. The way to get around this is to use 3/4 clean gravel which is 90 or better on proctors scale. 96 is considered compacted so that's the way to go. What happens is PB is likely to pour concrete deck and they dont worry about it cracking down the road and any voids under the slab they will be down the road when it happens. I also recommend fiber mesh added to your concrete it's cheap insurance

 

[SPman]

I can't say wether it is common with pools or not, but I would also be very concerned.
Placing then compacting in lifts, with proper soil moisture content, is the only way to get the soil to not noticibly settle down the road. I would imagine there is some piping in this excavation too? Settlement can downdrag the pipe causing stress and breakage. Any finishes placed on grade could crack or displace if not capable of spanning over the area. The criticality does vary somewhat with the soil type (sand better than clay), but I've still not seen a material that did not densify some in my 6 years of civil engineering.
That said, you can overdo compaction against a wall, and there is additional concern in that regard if the concrete has not yet reached it's design strength.

Yes there are pipes in this excavation, mostly on the very bottom ontop of virgin soil.

As stated different material needs different thickness and that depends on whether using a plate compactor or a jumping Jack. The latter is preferred. The way to get around this is to use 3/4 clean gravel which is 90 or better on proctors scale. 96 is considered compacted so that's the way to go. What happens is PB is likely to pour concrete deck and they dont worry about it cracking down the road and any voids under the slab they will be down the road when it happens. I also recommend fiber mesh added to your concrete it's cheap insurance

Yes, exactly. The PB pours a 4" slab for the pavers. I'm not ok with this, I don't cut corners. Thanks for the input gentlemen.

 

[jimmythegreek]

Make sure if you are overlaying pavers with a sand setting bed you use a geo textile fabric over the concrete under the setting bed. Trust me and its cheap

 

[Steve_in_C]

I over excavated when digging my pool. Instead of putting soil back, I used 57 stone. It has good compaction properties. The stone was covered with tough nursery grade landscape fabric with sand on top of that. My pool has not settled at all. I would not backfill with soil unless you compact in layers as you add it, or backfill and wait a long time (like a year) for it to compact again.

 

[PoolguyinCT]

Lift compaction is not necessary to the described scope of work.
If not in paid scope of work; buyer is not entitled to it without change a change order.

 

[BMK]

I remember asking my PB if they were going to backfill with the excavated dirt. He looked at me like I just insulted his mother or something. He said they only use stone and explained that generally, using the excavated dirt as backfill is a way for the PB to cut costs, but not necessarily in the clients best interest.
He may have just been talking about the soil around here as it's mostly clay and shale. Your situation may be different.

 

[SPman]

Lift compaction is not necessary to the described scope of work.
If not in paid scope of work; buyer is not entitled to it without change a change order.

Why do you say that lift compaction not necessary?

 

[Rich D]

Lift compaction is not necessary to the described scope of work.
If not in paid scope of work; buyer is not entitled to it without change a change order.

That might fly in commercial contractual work. However for residential contracts I would consider that devious behavior.
Almost every pool will have some type of deck around it which "should" have soil placed at a 95% compaction rate to avoid future settlement. To simply leave out this information and not make the homeowner aware of the possible outcome of improper compaction to keep your numbers down is devious. (In my opinion ). A clear contract with compaction options would be a very welcome addition to this industry.

 

[Rich D]

16x34 free form concrete wall vinyl pool

PB is backfilling with the soil from the excavation. They say they don't compact in stages, it will be one shot 48" deep. I'm speechless. This is not common right?

Unfortunately in this industry (poor or no )compaction it is very common practice. I had a mountain of sand placed as close to the pool as I could get it and still be out of the way of the excavation specifically for backfill. The Man running the equipment (The term 'equipment operator' would not apply to this lazy individual ) chose to put large rocks, large chunks of broken gunnite, wood and whatever else happened to be immediately next to the excavation in a 4' plus fill with no compaction. When I hand dug it all out I found very large voids that definitely would have settled over time.

 

[SPman]

It's ironic you mention that Rich. I have video of them pushing the overspill and washout from the truck into the excavation, on top of the plumbing; at this point I'm unable to say for sure if it's in direct contact with the pipes. The rest of the overspill was buried in the deep end.
They literally drove onto the site and started pushing dirt into the hole. Once it was filled to the top they did two laps with a plate compactor...

 

[Rich D]

I remember asking my PB if they were going to backfill with the excavated dirt. He looked at me like I just insulted his mother or something. He said they only use stone and explained that generally, using the excavated dirt as backfill is a way for the PB to cut costs, but not necessarily in the clients best interest.
He may have just been talking about the soil around here as it's mostly clay and shale. Your situation may be different.

You do need to be careful using stone for backfill against expansious materials as well. Without a sub drain, if surface water finds its way into the stone it will collect there and saturate the adjoining soil which can cause swelling and shrinkage.

 

[Rich D]

It's ironic you mention that Rich. I have video of them pushing the overspill and washout from the truck into the excavation, on top of the plumbing; at this point I'm unable to say for sure if it's in direct contact with the pipes. The rest of the overspill was buried in the deep end.
They literally drove onto the site and started pushing dirt into the hole. Once it was filled to the top they did two laps with a plate compactor...

I would love to see that video.. By code there should have been 6" of clean sand placed on all utilities before backfill. Actually code is usually "encased in 6" of sand" but the 6" under rarely happens.

 

[PoolguyinCT]

Backfilling with trash, as above is unacceptable.

 

[setsailsoon]

16x34 free form concrete wall vinyl pool

PB is backfilling with the soil from the excavation. They say they don't compact in stages, it will be one shot 48" deep. I'm speechless. This is not common right?

What standards are specified in your contract for this part of the work?

 

[Rich D]

Backfilling with trash, as above is unacceptable.

I would respectfully argue that ignoring standard accepted backfilling procedures for a structural area and installing a 4' lift with loose uncompacted material would be the same as backfilling with trash. They will both settle and leave a unsuitable surface for a patio placement.

 

[SPman]

What standards are specified in your contract for this part of the work?

Zero, shame on me for assuming this would be standard practice.

 

[Rich D]

Backfilling with trash, as above is unacceptable.

Linking this to your previous comment about contractual paid scope of work. I would assume there is no clause in the contract prohibiting them from using on site trash for backfill. So at some point known accepted standards should be enforced..

¯\_(ツ)_/¯

 

[Rich D]

Zero, shame on me for assuming this would be standard practice.

Yea.. The way I read that they do not even owe you a backfill. Just grade whatever is there to no specific grade within 10'