Hi, I have to swap out a leaky old manual sprinkler valve (galvanized steel) that connects to PVC. I want to put in a new master control valve (digital), likely with a brass ball valve before it (just in case I have to replace the master control valve down the line. The problem is the sprinkler shutoff valve is likely in the crawl space (need to confirm). Is there a risk shutting off the water main and swapping this piece out? Won't all the water higher than the valve I'm opening drain through the sprinkler valve when I loosen it? (I could open another hose bib to let the water drain to that point). I could check in the crawl space, but it is a small entry and I'm a little claustrophobic. . What are my risks for this <5 min swap out if I shut down the main water supply?