Advice needed on plumbing for adding a large waterfall

[carp3tshark]

I’m looking remodel my pool area and take an existing waterfall, increase its size and have it fall into the pool. The existing waterfall used to have it’s output come from the pool equipment pad and then the basin drained into the pool. The output was capped over and buried under concrete due to what I believe must have been a leak. I plan to keep the existing waterfall inside of my new waterfall grotto with about 95% of the flow going to the new waterfall dropping about 8 ft into the pool. The other 5% will feed the “inside the cave” waterfall that will overflow into the pool. Ok enough preamble, now on to the part I’m trying to work out in my head and can use some advise.
I wish to inline plumb a 9000gph high flow pump to feed the waterfall. My choices as I see them are to:
1. Replace or modify the pool skimmer so that it feeds the waterfall pump as well as the main pool pump. I would remove a section of concrete pool deck around the skimmer and add the line and re-pour.
2. Remove a section of concrete pool deck and dig down to add an intake line to the waterfall and intake screen in the pool.
Currently the liner is removed.
I plan on using 3” intake/output plumbing for the waterfall.
A. In scenario 1 Can a pool skimmer handle the flow of a 9000gph 3” pump AND the 1.5hp 1.5” pool pump? The only reason to do it this way would be to have one less intake in the pool.
B. In scenario 2, should I use a 3” bulkhead fitting for the intake line as it goes through the pool wall or is there another way?
C. Is there another scenario or way to get enough pool water to the waterfall pump?

Some pictures of the current setup and distance from skimmer to waterfall and a picture of a similar goal waterfall.

 

[JamesW]

You need to know the flow rate intended for each pipe. For suction, you want to keep the water velocity below 6 ft/sec. For returns, you want to keep the water velocity below 8 ft/sec.

Size.......6 ft/sec......8 ft/sec.
1.5"...........38...............51 gpm
2"..............63...............84 gpm
2.5............90.............119 gpm
3.0".........138.............184 gpm

9,000 gph is 150 gpm. There's no way you can use a single skimmer. A single skimmer should be limited to about 60 gpm.

I would recommend a minimum of two sets of main drains where each set is two main drains tied together and then a 2.5" pipe will go to the pump for each set from the T where the two drains connect.

You should have at least 4 main drains where each is a minimum of 36" away from any other drain.

Any underwater suction has to conform to VGB pool and spa law and local building codes.

Underwater suction can be very dangerous. Make sure that it's safe and conforms to all applicable codes.

 

[carp3tshark]

Thank you so much for your thoughtful answer, it is really helpful. You recommend a minimum of 2 @ 2.5” drain lines tied together with a recommended 4 @ 2.5” interconnected “main drains” at least 36” apart from each other. Is 2.5” an available PVC size? I get the concern that the multiple drains address, chiefly that underwater suction could grab a swimmer or small animal and either be dangerous to them and or the pump. I assume the 36” distance between is to give a better chance of one “thing” not blocking the suction? 12’ across the 4 interconnected drains would necessitate excavating and repouring a large section of the pool deck but is doable. I’d be curious at what depth I’d need to put these drains. Typically when I hear “main drain” I think of a drain on the bottom of the pool at 9’ depth. Having an existing pool that is already poured, it does have a main drain at 9’ deep, I doubt it would be easy or cost effective to add more main drains at that depth. I guess I’m hoping to get away with using wall drains. I want to observe codes for safety, but I also want to be smart about where I spend my money on this remodel. Do you know what section of plumbing code I’d need to review in this case? My municipality is observing International plumbing code 2003.

 

[JamesW]

I would say2 set of 2 drains 36" apart and Teed together and then 2.5" pipe back to the pump.

So, you would have 4 drains that would be at least 36" away from any other drain.

At the pump, you would have (2) 2.5" pvc lines that meet in front of the pump and T together and then go into the pump.

Each set of drains and the 2.5" pipe will carry 75 gpm for a total of 150 gpm.

The Intelliflo XF pump might be a good choice for the pump.

You should get a local professional expert to review your plans to make sure that they meet all applicable requirements.

 

[ajw22]

Your suction needs to be VGBA compliant. Read the links in Safety Drains VGBA - Further Reading

 

[carp3tshark]

Am I missing something when the VGB act states “public pools and Spa owners”? This is at a private residence are they subject to the VGB act of 2008? Regardless, it does sound like a good idea to have multiple wall suction drains spaced at least 36” on center. If I have to excavate a section of concrete pool deck anyways I might as well throw a few suction lines in. Any recommendations on what depth I should put these on the wall? Also, are there any flush mount drain inlets or do they all screw into the inlet pvc and stick out a bit?
I’ve looked at Products like:
Waterway (640-3580V) Super Hi-Flo Suction Assembly, Straight, 2-1/2", White, 180GPM (VGB)

 

[ajw22]

Am I missing something when the VGB act states “public pools and Spa owners”? This is at a private residence are they subject to the VGB act of 2008? Regardless, it does sound like a good idea to have multiple wall suction drains spaced at least 36” on center. If I have to excavate a section of concrete pool deck anyways I might as well throw a few suction lines in. Any recommendations on what depth I should put these on the wall? Also, are there any flush mount drain inlets or do they all screw into the inlet pvc and stick out a bit?
I’ve looked at Products like:
Waterway (640-3580V) Super Hi-Flo Suction Assembly, Straight, 2-1/2", White, 180GPM (VGB)

Public pools and spas needed to be upgraded while existing private pools were grandfathered. But you should not be able to purchase a non-compliant drain anymore...

By December 19, 2008, the Act requires:
Safety Drain Covers. Each swimming pool or spa drain cover manufactured, distributed, or entered into commerce in the United States shall conform to the American National Standard ASME A112.19.8 - 2007 Suction Fittings for Use in Swimming Pools, Wading Pools, Spas, and Hot Tubs published by the American Society of Mechanical Engineers (ASME). Compliance with this Standard will be enforced by the CPSC as a consumer product safety rule.

There is a wide range of drain covers available...

pool sunction vgb - Bing

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[JamesW]

There are rules that pertain to public vs. private pools.

In any case, you want to make sure that it's safe.

Check with a local professional expert to verify that all applicable codes are complied with for your installation.

 

[jimmythegreek]

You can retrofit a set of 2" wall drains down low that are VGB compliant and then use the existing main drains if they are dual tied drains and combine them at the pad to a 3" line and feed it. 150gpm is alot of flow have you seen that in action? I can run a 5' sheer decent of full speed with an ecostar or intelliflo VS and shoot water 3 ft with 2" plumbing