I know how this looks: a site talks a good talk about simple living and building naturally, then plunks a huge chunk of concrete in the ground! If we didn't know it before, we've heard from excellent friends about the toxicity of concrete, the problems with it's production, it's contributions to climate change, and on and on. Yes, but...
When we began this project, several other foundational methods were proposed, such as rubble trenches, rammed earth in old tires and earth bags. After looking at the research, we weren't convinced any of these methods would reliably support a massive cordwood wall, sixteen inches thick, and stave off the hazards of Wisconsin winters and the dangers of frost-heave.
In addition, concrete foundations are well-known in the building world and getting ours approved and installed was relatively simple.
Click on the photos below for the step-by-step process. Hovering over the enlarged images shows a title and explanation of each photograph.