We just had our 18' round pool removed, too. I'm mixing in the sand and vermiculite with added compost and topsoil. I thought of the pie shaped design, but I'm making the rectangular raised beds, 12 inches deep, to be more accessible and efficient. I am making a curved path on the outer borders of the bed area, filed with pollinator plants and lavender. I'm putting some thornless, erect blackberry bushes in the back of the bed area, which then leads into our newly planted mini orchard. Instead of throwing money on chemicals and electricity to run the pool, my soil will now work for me.