I'd love to post pictures, but I didn't get any. I didn't want to hold my buddy up.
I met him a couple weeks ago because we share a common interest in large military vehicles and we both own M35A2's (old school military 6x6 cargo trucks commonly called deuce and a halfs). We got to chatting about my OWB and the trench I had dug and I told him I was going to spray foam my PEX in the ground. He told me he's done it several times before and he still had contacts with the supplier his company used. He contacted the supplier and got me some old tanks of spray foam and then two brand new spray foam tank kits for me for FREE!!!
Yesterday, we decided to start at 7 AM this morning. At 6 AM I woke up and quickly laid down my 1" PVC electrical conduit and then put the 8' wide 4 mil thick plastic down in a U shape in the trench. It was 35 degrees out and very windy. It remained that way the entire day.
We started spraying my 1-1/4" PEX at the house with the old tanks of foam. It didn't set up well so we stripped it off pretty quickly. We switched to the first set of new tanks and went to town. We got about 60' done before those tanks were used up. We switched to the other new set of tanks and kept going. We had to stop once during the second set of new tanks to let them warm up again in the house. The foam set up fine in the 35 degree weather because the two chemicals mixing create an exothermic reaction. When we were all done, we wrapped the extra plastic around the foamed lines and called it quits. Took us about 2 hours to do my entire 80' and we put a bunch of extra in the hole through my wall in the house and at the OWB. I still have about half of the second set of tanks left including a brand new set of hoses and nozzles. I'm sure I can find stuff around the house to spray as well.
It pays to know people!
If you really want a picture, I can go snap a picture of the foam wrapped up in a blanket of plastic about 3' down in the dirt.