I decided to build a simple recessed cellar in my
yard that would serve a variety of functions, including rainwater storage,
root cellar and space for vermiculture (worm bins). All of these require relatively cool but not freezing conditions, so digging into the ground was a good way to accomplish this. It seemed like the easiest approach would be to build this primarily with earthbags. You can read all about how I accomplished this at
http://earthbagbuilding.com/articles/raincellar.htm