Screwed up my elevation... Any ideas?

DrawlGuy

Well-known member
Jun 12, 2019
45
Ohio
So I messed up... I just dug my entire pool at 46"...

When I go to lay my decking, I'll have 4" of topsoil in the way once I get 30" away from my walls... (past the overdig)

The excavator will be back this afternoon to finish up and the only options I can think of are:
1 - Have him backfill and pack in 4" to raise the bottom
2 - Have him take out 4" more all the way around the perimeter
3 - Fill everything with 4" of concrete (super expensive)
4 - Have 30-36" of decking coming off the pool (above my overdig) and then a 4" step to raised decking all the way around (seems like this would look weird)

Any other creative ideas that I haven't thought of?

____
Here's the "how I did it" if you're interested:
I have 33" of drop from corner to corner. I'd planned on setting the pool in the middle. I figured I'd bring the low side up 17", so I set my laser level at 17" plus 4" for cantilevered decking plus 42" for the walls plus 47" for the height of the level. That math worked and all was good.

Then I found out that my fill dirt would be clay and decided not to raise half my backyard with expansive material. So I changed the elevation to the low point and figured I'd do a 33" retaining wall on the far corner.

I should have just dug down 42". that would have put my decking on top of the existing ground on the low side. I didn't... For some stupid reason I just subtracted the 17". That made me 4" too deep.
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
4,912
San Clemente, CA
Whats the square footage? 4" of concrete probably isn't as expensive as you think, will be less problematic than trying to compact fill and will give you even more structural strength
 

DrawlGuy

Well-known member
Jun 12, 2019
45
Ohio
Whats the square footage? 4" of concrete probably isn't as expensive as you think, will be less problematic than trying to compact fill and will give you even more structural strength
954 sq ft. If my math is right, that's 12 yards at 4" deep. $135/yd = $1,620
 

DrawlGuy

Well-known member
Jun 12, 2019
45
Ohio
Your math is correct.

Whats it going to cost to backfill and hope its compacted well enough? Are you trying to get a certain depth of water?
So dropping the surrounding grade is the safest and cheapest option. (That might create some drainage issues on the house side that I'll have to account for.) My excavator ain't gonna be happy...

See any other ideas that I'm missing?
 

Divin Dave

TFP Expert
LifeTime Supporter
Oct 2, 2013
5,594
Longview, Texas
Welp,
these things do happen.

IMO, whatever you do, don't do No 4.

I would probably raise the bottom and stick with your original plan. No. 1.
excavating another 4 inches all around might present some other problems down the road.
 

mguzzy

Well-known member
Jul 8, 2015
614
OV, CA
I would do #1 and raise the bottom.. that way your plan for the decking elevations stays the same.. and your drainage plans stay the same... What about adding four inches of gravel or other fill that would be better that clay and a hecka cheaper than concrete. Sand or road bed gravel is pretty cheap if I recall. a number of people have put pools in in my area .. there is lots of fill dirt in my neighborhood.
 

jimmythegreek

Bronze Supporter
TFP Guide
Aug 10, 2017
1,158
Morris Cnty NJ
No issue to raise the bottom using clean 3/4 gravel. I use it to fine tune the bottom and then use 1/4 stone to fine tune the panels. A tandem load of gravel is under 500 bucks have them dump close to the pool and use the bucket to bring it in. Cover the whole shallow end and shelf and use it for the backfill of wall panels. Dont use concrete to backfill. If you have clay use a geotextile fabric on top of your compacted sub base then add gravel base for your decking. The patio I'm working on now is on clay I have 18" of base in, that's about 125 tons worth. Not moving anytime soon
 
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DrawlGuy

Well-known member
Jun 12, 2019
45
Ohio
No issue to raise the bottom using clean 3/4 gravel. I use it to fine tune the bottom and then use 1/4 stone to fine tune the panels. A tandem load of gravel is under 500 bucks have them dump close to the pool and use the bucket to bring it in. Cover the whole shallow end and shelf and use it for the backfill of wall panels. Dont use concrete to backfill. If you have clay use a geotextile fabric on top of your compacted sub base then add gravel base for your decking. The patio I'm working on now is on clay I have 18" of base in, that's about 125 tons worth. Not moving anytime soon
I appreciate the detail! I'd like to walk through this some.

You said "if you have clay use a geotextile fabric on top your compacted sub base...". I do have clay. When you say "compacted sub base", are you referring to clay or gravel? (So, compacted clay then fabric then pool crete or undisturbed clay then gravel then fabric then pool crete?)
 

DrawlGuy

Well-known member
Jun 12, 2019
45
Ohio
I just hung up with the Pool Warehouse tech line. (Great guys and I highly recommend them!) They said I take a big chance of having issues if I back fill due to expansion from freezing. I asked if I'm ok if it's deep enough that it won't freeze. They said, "no problem at all if you're beneath the frost line".

I googled around and the Residential Code of Ohio says that a minimum depth of 32" from finish grade to the bottom of the footing is required for footers. The US Dept of Commerce map shows the southern Ohio frost line to be in the 30" range.

My compacted clay would be 42"+ deep which is deeper than the frost line. BUT, it wouldn't be underneath 42" of undisturbed earth. It would be beneath a few feet of water, a liner and 2" of pool crete.

Would that still count as "below the frost line"?
 

jimmythegreek

Bronze Supporter
TFP Guide
Aug 10, 2017
1,158
Morris Cnty NJ
Yes its fine the water wont freeze that deep and the earth wont either. The only 2 things you can use to bring the pool dig up are clean gravel or concrete. 3/4 clean is known as #57 by you. Its 95% compacted out of the bucket. A light hand tamp or plate compactor and you are good I do it all the time. Dont overthink it too much. When the collar gets poured the whole wall is embedded in the concrete it's a huge footing. When I have bad ground and I have to overdig I throw fibermesh in the mix at 10dollars a yard to help me sleep good at night. The geofabric is for you deck and backfill area. Now to be honest I have it under my whole personal pool but I'm insane and over do everything but in your case dont bother I have water issues that's why I did it. The only issue you will have is with the walls of hopper you cant get gravel to stick well maybe a skim coat. What you do is make a plywood rip form around deep end to the transition of flat area and brace across pool with 2x4s to hold gravel and concrete in basically against the pool wall inside. You will need a bunch of cement bags and you mix in pool with a hose and flick it onto walls to eat up your 4" you can throw some extra stone in that as you go and pour the deep end floor from truck when you do collar to finish grade and work on that up to the walls
 

DrawlGuy

Well-known member
Jun 12, 2019
45
Ohio
Yes its fine the water wont freeze that deep and the earth wont either. The only 2 things you can use to bring the pool dig up are clean gravel or concrete. 3/4 clean is known as #57 by you. Its 95% compacted out of the bucket. A light hand tamp or plate compactor and you are good I do it all the time. Dont overthink it too much. When the collar gets poured the whole wall is embedded in the concrete it's a huge footing. When I have bad ground and I have to overdig I throw fibermesh in the mix at 10dollars a yard to help me sleep good at night. The geofabric is for you deck and backfill area. Now to be honest I have it under my whole personal pool but I'm insane and over do everything but in your case dont bother I have water issues that's why I did it. The only issue you will have is with the walls of hopper you cant get gravel to stick well maybe a skim coat. What you do is make a plywood rip form around deep end to the transition of flat area and brace across pool with 2x4s to hold gravel and concrete in basically against the pool wall inside. You will need a bunch of cement bags and you mix in pool with a hose and flick it onto walls to eat up your 4" you can throw some extra stone in that as you go and pour the deep end floor from truck when you do collar to finish grade and work on that up to the walls
@jimmythegreek This was a detailed answer and I greatly appreciate it!!! Luckily the hopper hadn't been dug yet so we avoided that mess. We knocked it out yesterday and hit the depth perfectly. I remembered that the first few trucks of top soil (non-clay) was dumped in my back 40 for a shooting range. We raised it some with that. I've got 60 tons of #57 showing up tomorrow to raise it the rest of the way and for back fill behind the walls. I rather not have the compacted fill dirt but I'm feeling somewhat ok with a couple inches of compacted soil 45" deep with a layer of gravel over it. All and all, I'm happy with how it's coming together!

Thanks again!
 

jimmythegreek

Bronze Supporter
TFP Guide
Aug 10, 2017
1,158
Morris Cnty NJ
You should be ok if you compacted it well. I personally wouldnt have used dirt. 60 tons is 2 stuffed tri-axle loads would be plenty for the lift and the backfill. Just make sure its compacted really well and use extra rebar pieces in your wall panels. When in your situation what I do is cut 18" pieces of 3/8 bar and make a slight V and use a bottom hole in the wall panel seams and insert and wire it up on a 45 degree angle. This way the panels are solid in the footing and cant sink over time if you get rust down below. I pin every hole in panels and tie ba I stakes too with rebar. Go a little heavy with your collar I go 8" with poor ground for more panel bite. Brace walls with 2x4s on inside too panels move with the weight of the concrete if not pinned well. Slope the concrete slightly away from walls maybe throw fiber mesh in your mix in case you get a settle spot so footing doesn't crack and spot sink way down the road. cheap insurance.