Essential to “double digging” your beds are the right tools. U-bar, broadfork, digging board, fork and spade. I am in a secondary floodplain. What little top soil the property may have had was used to make the 12 foot high pad the the house sits on. What remained was coarse mineral sand. The Kern River Oilfield is just across the river. It has been a “slow go” to build garden soil. Having horses on the property does provide one source of organic material!