your posts are the best visualization for the life i want to live. SO AWESOME.
you created a microclimate also!
Sepp Holzer describes in his "permaculture" book that he will literally use machinery to compress the bottom of pond excavations in order to avoid having to use any liner at all. but that only comes from theory, i sadly cannot tell you from practical experience.
page 49 and following, but the entire chapter would be relevant
edit: now that i reread the chapter i realize i even memorized it wrong ahahaha. but you are a resourceful guy.
blessings!