Build a short retaining “wall”around a pool ?

How to Build a Pool: Retaining Walls

https://blog.intheswim.com/how-to-build-a-pool-retaining-walls/

Hi! I don't know much about retaining walls, but, I remembered this excellent article about landscape around an above ground pool:

https://blog.thepoolfactory.com/landscaping-around-your-above-ground-pool

If your going to go four high with the timbers you will need to drill holes in all of them every two feet and pound rebar thru them and into the ground at least two feet. Otherwise they can tip over. Just use a mix of topsoil and peat moss for the plantings.

I don't see why you need a retaining wall around the pool unless it is a code for where you live. I have had above ground pools and would suggest you put gravel around the pool because there will be splashing and it would provide access for vacuuming and maintaining the pool instead of mud. Instead of plants that might not tolerate chlorinated water - consider small decorations like gnomes or trolls. Have fun.

To add to everyone's advice above... It looks like your deck is supported on a concrete block and that the legs of the deck are of pressure treated lumber. You don't say where you live but if you have termites, I would not advise piling soil up over the concrete block and on the lumber as you will just invite easy access for the termites to destroy your deck supports. Also, if your pool is galvanized sides, I would think damp soil will just promote rusting. Maybe fill with gravel as suggested above and then place large pots filled with seasonal color on top of the gravel. You can have a lot of fun with potted plants and some garden art. But again, avoid any type of material around the deck supports if you are in an area that has termites. Lots of luck and fun landscaping!

I would go one level with the landscape timbers and use stone or gravel. Lay down landscape fabric for drainage and prevent weeds before lating down the stone. Then plantings in pots and some decorative statues or similar.

I'm leaning toward the no wall idea. But, if you are committed to using the landscape timbers you have in the pictures, do what William said and add the "dead man" from Mogie's link. Also, don't stack a full length timber on top of a full length timber. You will need to cut some in half and stagger your joints between each vertical level. You should also weave the corners where two lengths meet each other horizontally. Buy a couple new 1/2 inch drill bits, the longest ones you can find at the store. You might still need an extension bit to get the full depth. Use 1/2 inch rebar. You will need a good size sledge hammer to do that much pounding. Use chainsaw bar oil on your drill bit as you drill to cool it as it will become very hot and dull quickly, and burn the wood doing that much drilling. Use the strongest drill/driver you can get your hands on. It may be worthwhile to rent a commercial size auger drill designed for drilling through multiple timbers the way you are planning to. Going through 4 layers, you need to make sure you are drilling straight down. If your bit wonders and you end up pounding rebar at an angle, it will pull your layers out of alignment. Back fill with soil staring at the pool. About 6 inches away from the timbers, lay in some landscape fabric, and complete the back filling with drainage rock, not the stone dust, which will compact too much or just use all gravel and no soil. Another method to help hold the wall in place it to sink vertical 4x4's in front of the wall and bolt them to the wall, the way you sometimes see wooden guardrails.

Here are some suggestions for you. https://www.gabion1.com.au/gabion-retaining-walls/?gclid=Cj0KCQjw3s_4BRDPARIsAJsyoLMetmUfh2NNQ_4s0r8af9MFKL1JVrT4bUVEHhRrFELqe0pnRo8LA6saAnI5EALw_wcB

I have an above ground pool and we put a deck around one side of the pool. We left the other side open but put these same timbers around the rest of the pool. We only went one up high because we had such a large trench dug around the side of the pool when they put it in. I am talking about 2 feet deep and up to 3 and 4 feet in some areas. The pool manufacturers said to not refill it with the dirt that came out but to instead put rock up against the pool wall and out for about 2 feet. Then to add either mulch or cedar chips. We instead added rubber mulch from the rocks to the dirt high wall. It has worked very well. We have had no problem with icing or condensation in winter from the water in the pool to the outside to freeze up. In the mulch i put stepping stones all around with plants. Has worked very well. Rubber mulch last for years.

With such a shallow depth, I would go with garden soil.

Here is a video https://www.youtube.com/watch?v=LfVOPqztUmQ

I would add a base of stones for drainage before you add the soil.