Sprinkler maintenance

In today’s golf course economy, money for capital improvements is hard to come by, especially for irrigation system improvements. So how can you improve the performance of your system, save water and not spend a lot of money? An inexpensive way is to make sure all your sprinklers are at grade. Additionally, making sure your sprinklers are level will improve your irrigation system performance.

Grade.

Sprinklers need to be installed at the appropriate grade. This varies pending on your sprinkler’s age. Newer sprinklers have much higher pop-up heights than older sprinklers, about 2.5 inches to as high as 4 inches where older sprinklers only popped up less than an inch. Newer sprinklers also have a much smaller area of the sprinkler that pops up.

Needless to say, sprinklers that are too high are unacceptable as they get hit and damaged by mowing equipment and are visually obvious to the players. The problem with not having sprinklers to grade is that they are too low. The grade of the sprinkler should be consistent throughout the course. When the sprinkler is too low the turf and or soil around it interferes with the stream. The lower the sprinkler, the more interference.

Once the stream has been influenced, the distribution profile of the sprinkler is changed, which affects the uniformity of the area irrigated by that sprinkler. As the uniformity lowers, more water and energy is used to compensate for the effects of the sprinkler being too low. The low sprinkler also affects close-in watering near the sprinkler as that nozzle may be partially or totally blocked. Low sprinklers also deteriorate the area around the sprinkler and provide a liability due to a depression. There is not much difference between a very low sprinkler and a valve box with no cover. Making sure valve-box covers are on has always been an important part of irrigation system maintenance. Low sprinklers are no different. You should decide what that height should be, ¼ inch below grade, ½ inch below grade or whatever and then keep the sprinklers at grade. You’d be surprised at the improvements that just raising low sprinklers will make to your irrigation system. Of course, you will have to free up the labor to set them at grade. Not a believer? Take a representative area of a fairway and set 8-12 sprinklers to proper grade and see the difference.

Level.

When a manufacturer builds a sprinkler, tests it and reports its performance it assumes the sprinkler is installed level. If the sprinkler is not level, then its performance will be different than what the manufacturer states in its literature. If it is not level, it will use the same gallonage at the operating pressure stated, but it will not throw the stated distance nor will it have the expected uniformity. Irrigation designers have always been taught to maintain the proper sprinkler spacing to have good uniformity, but what if maintaining the proper spacing puts the sprinkler on a 30 degree slope on the front right side of the green? Is that the best place for the sprinkler to have decent uniformity? Do you dare compromise the spacing to get the sprinkler in a level area? Many designers use set spacings and maintain that spacing no matter what. I was one of those designers in the past. However, as systems evolved many superintendents and irrigation designers have come to realize that having the sprinkler in the proper location is more important than maintaining the proper spacing. There are a number of reasons for this. When the sprinkler is not level its stream is severely distorted and that changes its distribution profile.

Today’s sprinklers have more nozzles available than older sprinklers, and different spacings can be compensated for with different nozzles. Not that I am a proponent of lots of nozzle variability, but you do what you have to. You could also influence the sprinklers’ throw by manipulating pressure. Lastly, some of the newer sprinklers have multiple, settable angles of trajectory. You can fine-tune for the different spacings with that adjustment. Keep in mind, adjusting spacing, nozzle or pressure will affect the sprinklers precipitation rate which will influence your run times. 
The effect of sprinklers on a slope can be seen just by watching one, but if you want proof, do a touch-can test and observe for uneven distribution. The sprinkler needs to be level even if on a slope. If that is not possible, you need to move the sprinkler to a better location.

Installing and keeping your sprinklers level and at grade will provide a better operating irrigation system. The challenge is in finding the labor and time to get it accomplished.