I was thinking condensation would build up in the ravine, with no way to get it out. Would the compressor have enough power to blow it out every spring?
If the condensation were to build up substantially, you could see 15 psi of back pressure given your dip under a 30 foot deep ravine. The pump wold have to have that available to push it out. And it would also have to have the flow (CFM) at that pressure to push it out quickly or the water would run back down the line and have to evaporate out. The real question is how much water would accumulate in the line...that I can't guess, but...
I would hate to dig under that size of a ravine and successfully keep the line from washing back out and exposing the line at the bottom. I envision running the air line to the ravine, surfacing and running some steel pipe across the ravine, and then back under ground to the pond. A couple hedge posts on each side configured like the end of a fence at a gate (with the cross brace), along with a cable stretched over the ravine would give you the support. Then. weld some hooks on the steel pipe periodically to catch the cable, fasten the pipe to the fence posts and your set.
Is it ok to “not” run it for a few nights here and there during the summer?
I bet skipping a couple nights every now and again would be fine. I would be concerned to skip more than 3 nights in a row, especially in the heat of the summer. Maybe someone knows how quickly a pond can re-thermocline?
