Well, this is the location we have selected. It's adjacent to the launch road and about 100 feet away from the pond. The soil is hundreds of years of dead leaves and roots in topsoil. We can't build on this unstable foundation, so I start pushing the shovel. About 8-10" down, we hit hard clay; a perfect support for a slab. Although one would think that soft loamy topsoil should clear out quickly with a shovel, the incredibly thick lateral network of roots make this a major project.