And then a year passed.
Appalachian Trail and then to bicycle across China (again). He took a liking to the hot tub plan and started digging for a few weeks. I spent most of my spare money buying and renovating the trailer you see in the picture for him to live in (guest house). So at this point I had a big hole with a bunch of earth bags filled. My friend decided to go hike the AT for the fourth time, but I had a little money saved so I started working on it again. Basically for the past three weeks for 3-4 hours a day I have been filling bags and mixing cement to plaster over the bags.
I had an old bathtub which is the white thing you can see on top of the bags in the picture at the top. That is going to be part of an outdoor kitchen eventually. There will be a prep area to the left of the tub and a brick oven (wood burning) across from it. I also plan to build a screened in area behind the hot-tub so that during the summer I can sleep outside in that without having to worry about the bugs. The eventual goal is to figure out a way to manage with about $1000 of solar panels. This will mean limiting electrical use as much as possible and air-conditioning will have to go.
In the end this "hot-tub" will not be that cheap. I estimate I will spend about $600 on sand, $400 on cement $500 on gravel, and $300 on the various plumbing. So basically round it up to $2000 or so. But it should provide a lot of bamboo and will be the starting point for a lot of other projects such as an aquaponic garden, fish farm / cistern, and mushroom growing bunker... more on that if I ever get that far.
If I were doing this again I think I would make it about 1/3 the size. Especially the filter. I think I would make it about 10 feet instead of the current 30feet (which is excessive). That would probably cut the labor and cost in half and accomplish basically the same thing.