30 ton rock waterfall/slide combo question


New member
Feb 23, 2021
College Station, Tx
We are currently in the process of having our pool built. (This is our first pool so this has all been a learning process). We wanted a slide and moss rock waterfall combo. Our builder suggested the 15' garden ride slide so that's what we went with. He quoted us 6 tons of moss rock for the waterfall/slide enclosure. Well once construction got started on the waterfall itself, he realizes he way underquoted the job. So far we are up to 24 tons of rock and it's still not complete.....

One big concern we have is if the pool side beam and waterfall pad will be strong enough to hold all of the weight since it's way more than the 6 ton that was anticipated. When we ask the builder and stone mason they both tell us they think it should be fine. But it worries us that we may have issues later on. I am including a picture of what the waterfall pad looks like and what the waterfall looks like currently.

The waterfall pad is 12' x 16', 3/8" rebar on 10" centers, approximately 5" thick, and 5500 PSI Shotcrete.

The side of the pool is a 12" beam, 1/2" rebar on beam and then the rest is 3/8" on 10" centers, 5500 PSI Shotcrete.

Does anyone have experience with a waterfall/slide this big? Any thoughts as to if our pool/pad can support the weight?

Thanks for all of your help!!


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Rich D

Bronze Supporter
Aug 3, 2018
Let's see if @Rich D is around.
Just coming out of winter hibernation up here in the NE... :)

Good news is it looks really nice. I love the large rocks. If you click the link in my siggy you will see I am a big fan of big rocks..

My guess would be the PB is out of his depth on this one. Anyone who has worked with rocks would know 6 ton might get you 12- 18 " out of the ground with that type of build.. Hopefully the Mason has some previous experience with water falls. We're you able to see any of the masons prior work?

As far as the support goes for all that weight, I am not a engineer so I can not give any details on what would be required. I have been in the construction industry for very long time so I do know what engineers spec for different applications. 5" sounds too thin to me. Industrial building floors that support heavy equipment and fork trucks are poured at 6" thick. Loading dock pads that support tractor trailers are poured at 12" thick.

My waterfall is a submerge shelf that has 6" of water on it. It is 27" thick. The rest of the Boulder wall sits on the reinforced pool beam wich is 18" thick. I have attached the plan details.

A few more things concern me.
It would appear the 5" shelf is tied into the pool beam and it appears from the pics the shelf is raised from original grade. If they did not dig out any unsuitable material and replace it with clean stone or properly compacted structural fill then it could settle and take the pool beam with it.

It also appears from the pics the elevation of the pad is the same as the pool beam. There is no way to completely seal all of that masonry. So if it leaks down to the slab it could just flow into the side dirt areas and you could end up with a significant leak going down the sides of pool.

As stated I am not a engineer However in my humble opinion I would certainly seek out a outside engineering opinion. When you asked the PB about it, his response should have been "It has been stamped by our engineering dept". I would not be comfortable with " I think it will be OK"

Post back if something is not clear or you have more questions...

Hopefully others with chime in as well....

@bdavis466 might have a opinion on these issues..

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