Rainy Day halts construction - part 4

It's raining in Wisconsin today, so I left outside construction work on the greenhouse on hold for today and maybe for the weekend? I feel kind of like the Jack-o-lantern above, the one in the middle!

The photo on the right is where I was able to back-fill to yesterday while the ground was still dry. I'm to the point that I need to start laying out the greenhouse base and then back-fill to it, I bought the stuff I intend to use for that yesterday.

I made another trip to Menard's yesterday morning and bought 2 x 6 studs to frame the base of the greenhouse, more pink polystyrene insulation and some 1 1/4 inch conduit to pound in the ground to anchor the base and to insert the 1 3/8 inch top-rails that will form the hoops.

I spent another $200+ dollars and I'm sure I'm running way over budget by now, but I'll assess the damage when it's finished. I have cut corners to save in other areas when possible. One area is in the back-fill.

Back Fill

I'm not sure if I've explained this already, but I'm using the same dirt/clay that I excavated as my back fill. I know that some of the plans I've consulted call for #18 stone to be the back-fill around the slotted drain tile. The problem that I have with that is money. It would have cost $700 - $800 dollars to have a load of rock trucked in and I'm not sure if that would have been enough, too much, or just right, I just didn't feel I should spend that amount for rock when some sites are reporting using mud as back-fill and then drying the mud out and observing no difference in heat storage.

What I decided to do instead is to increase the length of buried pipe by 200 feet (about 40% more than I originally estimated I needed) since the pipe is only $32 per 100 feet and then just back-fill with the dirt I excavated.

I don't know if my estimates are correct anymore because I've changed the projected greenhouse size. It doesn't really matter, because I don't think this is a proven science anyway so it's all just trial and error and I'll probably make lots of errors! However, I might try to run my numbers on Sunny John's Subterranean calculator tonight when I get back from work to see if I'm actually close to what they suggest for greenhouse size and the subterranean heating/cooling network.