In Greenkeeper's circles the so called happiest day of the year is when the irrigation system is winterized. To do this the water is drained and in today's world we use a compressor to blow air into the system and force the water out. We call this "blowing out the system". Our main line here is the original from 1936 and is 5-7 feet deep into the ground. This is below frost code and so back in the day there would always be a drain on the system at a low point, possibly several which would be used to get the water out of the laterals and or higher pipes. Any water remaining in the mains would be deep enough not to freeze. Not fool proof, but I am sure adequate since the pipe is still in use and functioning after all this time. We have 18 abandoned galvinized water lines that froze one year. We repaired these and put some form of valve or spigot to be able to "blow them out" every year to avoid them freezing again. Make that 19. While writing this I remembered the pipe under the 5th green we discovered last fall while aerifying (see the blog post here). This has never frozen, I assume because it is a high point, but tomorrow I will open that valve and let the water drain to a lower spot just to be safe, if it hasn't done so already. Remember water always seeks its own level even inside pipes. As soon as the pumps are shut and the pressure is drops the water does all kinds of weird stuff. The snap valve behind the 8th green was weeping at 14 psi. There was not enough pressure against the spring to keep the seal tight so even though the water was off and down from the normal 115 psi it was draining all the golf course pipes above it for days. We eventually shut the feed valve which was actually down hill to make it stop. Another epiphany during this post was how this favorite day of the year scenario is a northern climate one. I assume there are many areas that keep their system charged all year. Their comments to this are usually "yeah but we don't have to plow snow!"
We have had a fairly wet fall this year so the need to water was diminished. Rather than wait until it would be the most miserable of jobs, usual timing, I decided to blow the system out early. As I teased my friend who went out a week earlier saying it would be too warm and just not feel right he responded "yeah but it will be fun in shorts and a beach chair". All kidding aside my favorite worst memory is the day we started in carts and had to move to 4x4 trucks because we had about 6 inches of snow fall as we were blowing out. We also had a four wheeler do a donut on the second green with about 3 inches of snow that day. Took a week but the snow melted and we chose to strip the damage and sod from the nursery. Good times.
To go back to the thought of drains on a system. The original map shows a pipe teeing off the main loop near the practice green and heading down between the cart barn and clubhouse. We had a valve break closed on the main a few years back and when we dug that up we eliminated this tee since I really did not want to ever see the end of this pipe. On the map it goes straight through the parking lot into a pond. The pond now has a house in the middle of it as they back filled to create the land. My worst fear was this pipe rupturing and flooding their basement, if they have one. The only downside to abandoning this section of pipe was we lost the feed to the sprinklers on the p-lot side lawn. I never knew they were fed straight off that pipe until we put 2 and 2 together. Within a couple of years we re-built the clubhouse and tore up the lawn anyway. Now that section and the flowerbed sprinklers are on town water off the building. Which is a good thing for the shrubs since we have salt water in our irrigation well.