I think there is some miscommunication on my part . I am just building a gravel foundation that will be 12x16instead of a slab. The shed will then be built in the gravel area. The shed I am planning on building will be 10x12. So really I wanted to see if I should even worry about removing the mulch or just place the gravel on top. As for the 2 8 fr post that will be just used more as boarder for the gravel area in my yard .