What you have as a base material is a product called “gunnite” That is a near dry mix of portland cement, hardner, and finely ground strong plastic fibers. That material is then sprayed onto a form and the swimming pool is formed.

So to repair this take a scraper and chisel off every bit that is lose around the holes. The size of a dinner plate will eventually be much larger, about 30 inch dia or so when you get at it with the scraper. So dont be that surprised when this happens.

Next, get some regular Portland cement at Lowes about $8.75 for a 90# bag. Mix that at a ratio of 1:1 with a coarse sand that you can get from any stone quarry. That stuff is cheap, so when you go to the stone quarry take about 5 or 6 of 5 gallon pails and get enough. Probably cost you like $5. for the lot.

DO NOT USE MASONS SAND The strength of repair lies in the larger particules.

Next mix in the hardener. You can buy that at Lowes too about $15 a gallon or so. Also mix in about a one cup of regular latex paint to about 2 gallons of total mix. This latex acts as a “binder” and allows the mix to be troweled onto the wall. Without it troweling will be difficult, if not impossible. Now add water until this mix becomes the consistency of toothpaste.

Next wet down the surface of the damaged spot with water and wait about 15 minutes for it to soak in good. Then take a flat trowel and apply a thin coat of this mix. Rub it good into the surface. Rubbing is important as it impoves the bond.

Trowel it on there until it is say 1/4 inch or about that HIGHER than the pools wall surface. Wait for about 2 hours and let it set up to the point it hardens, but can be scraped with a sharp tool. Then take a sharp piece of steel edge angle iron and scrape that thing dead level. It will shear off just like cutting excess butter from bread.

Dont be alarmed by nicks or gouges that you might make, let it harden overnight and go back next day and made another mix and smooth it out to a very very fine finish as you work that mix on top of the repair.

Paint and no one will ever know this damage was there. This is a permanent repair It will last indefenitely. The cost for the entire pool will be less than $20 im sure assuming you furinish the elbow grease for the job.

Use Hydraulic cement, it’s available at your local hardware store or home improvement center.
You’ll have to paint it, but it’s the best thing for the job that you need to do.
Hope this helped, good luck!!