# Backyard soil sinking



## r___r (May 5, 2015)

greentrees,

The 2' depression isn't a big problem. The ground where it is sinking(settling) is compacting itself, naturally. This probably could happen the whole pit area the pool was setting in. Water is loosening up the dirt, causing the dirt to fill in the voids. 'Water Jetting' is one method to compact the soil, but, it takes a long time for the area to stop settling, drying up, and become solid.

For a quicker method to make sure the ground is solid again, have the PO outline where the pool was installed, rent a compactor, and run it a few laps around the whole area the pool set in. You'll probably find out that more dirt will need to be added. Add the dirt and re-compact until the pit is level and solid with the rest of the yard. To get good compaction, dirt should be added in 4-6" lifts, then compacted.

http://www.homedepot.com/c/compaction_equipment_rental

There's lots of videos on youtube for reference of operation.

Rich


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## greentrees (Apr 28, 2012)

r___r said:


> greentrees,
> 
> The 2' depression isn't a big problem. The ground where it is sinking(settling) is compacting itself, naturally. This probably could happen the whole pit area the pool was setting in. Water is loosening up the dirt, causing the dirt to fill in the voids. 'Water Jetting' is one method to compact the soil, but, it takes a long time for the area to stop settling and become solid.
> 
> ...


I was surprised that the hole was just in one area, and looks about 2 feet deep. So I guess the dirt that was there either sunk down, or got spread to the other areas. 

For a compactor, how long would it take to compact a 25 foot circle area. I would probably need some extra dirt ready since the soil will probably compact half a foot or so. After the compaction, would I be able to put a shed on the area, or is it better to wait a few months to see if the soil settles more?


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## r___r (May 5, 2015)

greentrees said:


> I was surprised that the hole was just in one area, and looks about 2 feet deep. So I guess the dirt that was there either sunk down, or got spread to the other areas.


To many 'Could Be Because' to guess why only that area is sinking.



> For a compactor, how long would it take to compact a 25 foot circle area.


If the circle area is soft, it will take more time to compact for the lift to be solid. Maybe an hour a lift.



> I would probably need some extra dirt ready since the soil will probably compact half a foot or so.


Hard to say how much dirt you'll need until you know how much the area will compact.



> After the compaction, would I be able to put a shed on the area, or is it better to wait a few months to see if the soil settles more?


Just make sure to take your time to get good compaction on each lift. Make a few complete passes over the whole area. Start from the outer area and work your way to the middle, then repeat as many passes as it takes to get the compaction needed. When the Wacker doesn't compress the dirt anymore, and has a solid sound hitting the dirt, that'll be a good compacted lift. You'll be able to construct your shed.

Rich


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## Bud9051 (Nov 11, 2015)

If you are looking to buy it would be appropriate to ask for an engineering report to confirm what is happening. I've filled a lot of holes and never had one sink that much.

Old septic or a drainage path would be my immediate thoughts, but I have seen deep holes where drainage is carrying away the top soil.

Anyway, an engineering report would not be that expensive and would provide an answer as to why and how to fix, AND eliminate some unforeseen major expense.

Bud


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## greentrees (Apr 28, 2012)

The hole looked like a drainage area, so was concerned that it would repeat. Anyone aware if a semi inground pool needs a drainage pipe in the ground. Or maybe it is a drainage pipe for the backyard. Though i don't see a need for one in that area just for the backyard. 

For the compactor I assume renting one for the whole day would probably be best, if I go that route.


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## TGMcCallie (Nov 12, 2011)

There is no need for a drainage hole in a above ground pool that is installed only 2 feet in the ground. You drain them out with a pump.

Personally, I would call a home inspector for a complete home inspection which would include this area. That will be much cheaper than an engineer.

This would also let you find anything that could be wrong with the house which is a greater concern than this hole in the ground.


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## greentrees (Apr 28, 2012)

TGMcCallie said:


> There is no need for a drainage hole in a above ground pool that is installed only 2 feet in the ground. You drain them out with a pump.
> 
> Personally, I would call a home inspector for a complete home inspection which would include this area. That will be much cheaper than an engineer.
> 
> This would also let you find anything that could be wrong with the house which is a greater concern than this hole in the ground.


If I get into contract, than I would hire a home inspector. They won't be able to do much since the owner filled in the hole and put the brown bark over it already. When I went to view the house during an open house, the listing agent said that the pool was an above ground pool and the owner did not sink the pool down into the ground. A bit contradictory to what the owner said. I assume she didn't want to say anything since it was already covered up. 

Either way, I would still compact it if I end up buying the house and wait to see if the hole forms again.


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