Looking for Suggestion/best practice

[LakeTimes]

Told my neighbor I would check on here as I recall seeing some suggestions to this in a thread from years ago, but can't seem to locate it anywhere.

Essentially over the winter the water has washed out the mortar under the cement retaining wall causing it to lean. With the high lake level and waves, it has washed out a lot of the sand from the beach. The thought was to dig the sand out on the backside of the wall and drop in cement (again temporary fix as he's not looking to spend a lot of money).

I recalled that there was a special kind of cement that comes in a bag where that you can just drop the bag in, soak with a hose and it turns into cement. The bag is some kind of biodegradable bag making it easy, quick, clean and also preventing any cement from going anywhere.

Does anyone recall this or where you can get this?

Open to other thoughts or suggestions that I can pass along. Thanks!