How do you repair a washout in an above ground pool?

We experienced a wash-out on the back side of ours last year ( forgot to turn the gutter spout away and ran off of bank, under the pool sides and washed out on back bank). We had never put one up before and used too much sand. However, we placed some alum. strips (approx. 4"W x 6-8"L x 1" thick) on each side where it was still level with the ground. In between we used 1/2" thick scrap fiberglass boards (no wider than 4"). You don't want them too wide to reach into your liner. We drove these (sometimes wedging an extra between the boards) in 2, 3,or 4 stacked until our bottom ring and one base plate was supported. Used a slightly bigger one under the plate. In between these, where we could, we filled back in with dirt and packed in using our hands, then tamping down with solid board. Then, we stabilized with more dirt upon the bank. Our liner stretched and filled the void over time. Use something other than rock (which can shift) or wood (which will rot), for your filler. We never had any more problems the rest of the season.