Underground greenhouse

I couldn't find a tread for this so thought I'd start one   i have a defunct swimming pool, 20  x 40 feet. At first I put 200 baby catfish in it so they could grow big enough to not be eaten by the bass in the 2 acre pond.   I had a musk rat get in and cleaned out every one from the pond   this worked great  but now I need to do something with the pool .  I have decided to make an underground green house out of it.   I know when i take the liner out will have to put in a retaining wall of some sort.   Any suggestions?   Eventually I will put old refrigerators, freezers,  and dishwashers around the top to not only grow in but to be a solid railing so nobody falls in. I also have the old wood burning furnace we had to replace from the house.   I want to refurbish it and put it out side of the green house to pipe in heat for it.   I've never done anything like this so all the help and suggestions are very much appreciated.

I am unsure if this is universal, but around me most ingrown pools have concrete "retaining walls" behind the plastic liner.

I think managing surface water ( keeping it out of your "pool") will be important, but this is an interesting concept.

I saw someone on youtube who did this in a hot area (Arizona?) and with a shade cover over it had a glorious place to grow stuff.  The farther you are from the equator, the less sun you'll get in there in the winter.

I am familiar with that particular group. The problem is in Arizona and most of the south west is they put in a pool by digging a hole and putting gunite on it (kind of a cement) .  That is why the Beverly Hillbillies called it a cement pond.   I moved to Tennessee from Arizona and was shocked to find that in Tennessee they put in a pool by digging a hole and putting a plastic bag in it.   Which is why I don't know what is behind the plastic bag.   I would have thought that they would have had to put a retaining wall behind it but at one spot it is starting to crumble.   Which makes me suspicious of what I am going to find. They may have just counted on the water pressure to hold it.   The other thing is the pool was put in 40 years ago, so who knows.   If it's like the of the house, the workers cut so many corners.   They may have saved 1000 dollars but it's going to cost me many tens of thousands to fix..  we are not the original owners.   Thank you for your suggestions

John  Young, that is encouraging.   I guess I will be finding out this spring.   The pool does sit at the bottom of a sloap and a lot of rain and flood waters always run into it.   We are definitely going to have to ditch around the end.   Once the green house goes over it we should be able to seal it better.   Thanks for the info

Check out the Forestiere Underground Gardens in Fresno, California.

Very interesting.   I love the arches. Thanks for sharing

I have a concrete/gunite in ground pool a little smaller than your area.  Just telling you what I did with it, not suggesting anything.

The people in AZ (not sure if it's the same people that were mentioned before in the other posts) that I loosely copied go under the business name of Gardenpool.org or something.  I think they now consult people on how to turn their in ground pools into greenhouse/growing areas.  Some cool ideas on their site, and I think years ago they posted on this site.

I first tried doming my in ground pool similar to how they did and using it as greenhouse.  It got over 100F in January when the outside temperature was more like 50F (I'm six miles from northern AZ border) so I had to have a fan running all day to keep it cool.  It would still drop below freezing at night when the temps outside got below 30F.  I found the extreme swing in temperatures annoying.  I tried keeping a couple of hundred gallons of water in the deep end to act as a heat battery, but it didn't seem to help much other than right above the water.
I gave up on it after a few months.  I was just getting into gardening, had no idea what I was doing, and sometimes think I might try it again now that I know a little bit more.

That being said, that same pool has been my chicken coop, compost pit, wood chip reservoir, compost tea brewer, egg making, FIRE ANT breeding, science project for the last few years.  By filling the pool with free wood chips, I am now able to make all of my compost on site.  It is a lot of labor to shovel the chips into a garbage can, haul the garbage can up the stairs of the pool, over to the screen sifter, and then sift out the bigger chunks.  All of my food scraps go in the pool, all the yard trimmings from the property (I'm on 1/3 acre urban with no lawns), and pretty much anything organic I would otherwise throw away.  I put hardware cloth over the domed area where the plastic for the greenhouse was.   The compost tea is basically just rain water that the pool naturally collects and that I can pump out with a bilge in the deep end.  My area has had so little rain the last year I haven't pumped any tea/water out for the last year.  There has been water under the wood chips for the last year, though.  It is accelerating the breakdown of the wood chips, and there is a certain sweet spot of moisture where I have a vane of mycellium/fungi growing.  The top layer is dead and dry, but several inches down is full of life.  Worms, and all kinds of insects.  It's ugly, but it works really well, and it produces quite a lot of food (eggs), fertilizer (chicken manure), and again all the compost I could ever want.  

I don't really have any predators to cause problems.  My chickens free range a lot of the year outside the pool, and I leave the door wide open 24/7 and have never had any predator cause any problem.  Occasionally a neighborhood cat will show up in my yard, but again, I never lost a chicken to predators.  I also have not noticed any rat problems here.  I'm sure there are mice, but they've never caused any problems for me.  The wood chips eat the small of the chicken manure and food scraps.

Here's the website for gardenpool.  https://gardenpool.org/  I think they have some videos on youtube as well.

I've posted tons of pictures of my setup in other threads I've made.  

Good luck, I'd love to see pictures of what you end up doing with it.

Edit, here's the video that inspired me.  



Thanks,
Josh