The planting mound, or bed, can be created in many ways. The easiest way is to use the topsoil excavated from the swale itself, but often other materials are already on hand and can be incorporated into the mound design. I call this a debris mound, and it’s not so different from building a compost pile.
When choosing the placement of your swale there may be grass, weeds, brambles, leaves, bushes or even small trees that are in the way of the excavation (make sure none of these plants is valuable and consider transplanting if that’s the case). These materials can all be, and in my opinion should be, built into the mound. Read the full article under https://www.