Pool renovations - are our pool and patio one solid pour

[Household6]

We DIY’d our pool surface about six years ago at a cost of around $2k versus $30k quotes. We didn’t expect the repairs to last more than a couple years before we had to redo it again, but turns out we got a solid five years out of it. No regrets.

The house was a rental property at the time of our first stab at it (courtesy of the Army). It’s time to do it again and as we have since moved back into the house, are considering tackling a bigger issue . . . the shallow end of the pool has sunk over the last 40 years, the last ten of which we have owned it.

The highest water line on the shallow end sits at 2.5”. The lowest water line at the deep end is at 9.5”. This is a 2” increase in difference over the last ten years. So it’s a gradual thing. (As we live somewhat near where artillery training is done, our belief is that the ground tremors from the training might have caused a portion of the property to settle over time.)
In considering our options, we have come to wonder if the pool and the patio that surrounds it are connected - as in they were poured at the same time. It’s a bit mind-blowing to think this could be the case, but . . . well, look at the photos.
The former owner of the house had a lucrative asphalt business. Is it possible he really knew his stuff and was able to make a solid pour happen?

 

[Household6]

Any old-timer builders with some thoughts?

 

[jimmythegreek]

If its 40 years old then its not a single pour. Nobody in their right mind would do that anyway. It's all prob just fill and has settled together. If you are gonna Reno it you could have some core samples done and see what's down there. If its stopped sinking a common fix is to build up the low area beam and do a new decking to that height

 

[Household6]

If its 40 years old then its not a single pour. Nobody in their right mind would do that anyway. It's all prob just fill and has settled together. If you are gonna Reno it you could have some core samples done and see what's down there. If its stopped sinking a common fix is to build up the low area beam and do a new decking to that height

The visual says otherwise, but agree it doesn’t make sense.

Can you explain what “fill” is to me?
and “low area beam”?
Who does testing on such samples?

 

[jimmythegreek]

Geotechmical engineer. He will have a guy that will bring in a boring machine and drill core samples and pull up the material down there. Fill is dirt moved around that is either native or non native. If theres organics down there or trash it breaks down over time and settles. Kind of like where am old stump was it makes a void.

If its done settling you add to the bond beam and build up the low area to make pool level again. If I understand the pics you have settling correct? Or am I reading it wrong and its heaved up?