(how often do you read about those?) Due to the fact that our western wall will be the highest part, and has some tendency towards straightness, we decided that we should have a couple of buttresses connected to them to help stablize them in the event of an earthquake.
That means we need to have stem walls for them as well. That keeps the ground moisture and possible rain splash back from messing up the cob mixture. These will mostly still be under the roof line, but Melissa is on the job mortaring them together.
Above she's working on the southern one, and below is the northern one (both on the west, obviously). The little tunnels in each one are made from a small section of 4 inch plastic drainpipe that I had laying around that will allow the gray water drain system to easily pass through that area. You can see the bathroom sink drainpipe coming around the corner in the photo below.