DIY Adding Pool Retaining Wall w/Linear Waterfalls

[Carl543]

I want to add a retaining wall about 2 to 3 ft tall and the length of my concrete in-ground saltwater pool which is around 30 ft. long. It is South Florida. In that space now, I have a grass strip. I want to put in two linear waterfalls in the new (glass-tile-coated) retaining wall. 

About 15 ft away from the pool, the pool pump, etc., is above ground. I was going to build the retaining wall out of cinder block and concrete and run new PVC lines to the existing plumbing where I would cut into the return pump line that feeds the jets now and add manual or smart valves.

I tried to recruit local pool companies to advise me on this for a consulting fee, but I couldn't get any takers so I am looking for advice from experts. I've done a variety of home DIY projects, various woodworking, PVC work for home, irrigation, and saltwater aquarium purposes, and I've built landscaping retaining walls, but I've never done work on a pool or much work with concrete or tile.

Do I need to drain the pool before I dig out the grass along the edge of the pool? I will put crushed gravel in for the footer of the retaining wall, but I don't know if the water pressure from inside the pool could damage the pool wall if the wall doesn't have soil behind it while I'm doing the work.

Would it be better to run two separate PVC lines, or can I run a single line to a middle point between the two linear waterfalls, put a tee in, and then run equal length lines to each new linear waterfall? The waterfalls will have valves at where they are fed so each can be adjusted in terms of flow there, and I will put them in an irrigation or other box at the surface so that they can be adjusted later as needed.

Any other advice? For the wall, I was going to put in the crushed gravel footer, put three-high standard cinder blocks in a double row overlapping each other, put some rebar through them and fill them with concrete except where the pipes need to come up through the ground to get to the linear waterfall intakes, and then cover everything with thin set and glass tile plus grout. Should I change my plan? 

 

Again, I'm new to a few pieces of this, so I would really appreciate any advice!

[Carl543]

Hello. Any advice on this? I'm thinking of swapping to a concrete footer for the wall too.