I am establishing my 1ft step back into our slope cut for our above ground frame pool. That makes a space of 1ft between the edge of the cut and the wall of the pool. The legs will sit on 4x8x2 Blocks set flush with the base. Our dirt is about 30% rock, from pea size up to 6". (Fun digging.) There will be pool water splashover and rain, that will fall into that 1ft step back area that will want to go under the pool. What do i use in that zone, to prevent erosion and undercutting of the sand and dirt that is under the base of the pool.