One of the last maintenance procedures to accomplish before the field rests for the winter is to winterize it, to make sure it is ready to experience whatever Mother Nature throws at it over the next few months. In addition to the prevention of broken pipes and system components due to freezing and expansion, this is a good time to investigate obvious flaws and needed additional maintenance procedures.
Selecting an appropriate compressor is crucial to the process.
PHOTOS BY BRAD JAKUBOWSKI, DOANE COLLEGE.
The importance of timing cannot be stressed enough. Experienced sports turf managers have learned that every application they make — every fertilizer, every grass seed, every insecticide and every drop of water — is most effective when applied at the proper time. From a timing standpoint, winterizing is no different. Several factors have to be considered in order to determine the best time to begin the procedure, including the projected usage in late fall and early spring, the quality of the existing turf, the current need for renovation/late-fall overseeding, and the number of fields and available labor force to get the job done.
Without a doubt, technology has become a best friend in winterizing an irrigation system. Through various apps, websites and on-site weather collection devices, there are multiple opportunities to gain insight into up-to-the-hour weather patterns. It takes time and effort, but monitoring various forecasts and tracking weather patterns provide valuable insight into timing for the current season. The overall goal is to make sure that the turf root system is thoroughly moist to support the needs of the root system without leaving water in the system components that could cause damage.
Another important part of timing is the realization that all aspects of winterization don’t have to be completed in one day or one single operation. In fact, a flowchart or simple outline of a step-by-step series of actions can be helpful and bring order and efficiency to the winterization process. Additionally, once the plan is developed, previewing it with the entire staff is helpful in making sure everyone knows which jobs are going to be worked on when, and who is responsible for each task.
In the days before the majority of the winterization steps are to be taken, small steps can be completed that will make a major difference in the end. These include:
- Reviewing the parts inventory to make sure all items are in stock for replacements and repairs during shutdown
- Gathering the necessary tools and fixing leaks
- Making adjustments and updating notes for component improvements for the following year.
Look back for help
In most other aspects of field care, such as insect emergence and weed germination, field notes taken on a weekly basis provide help when choosing the course of action in the current season. Detailed notes on how the fields were winterized in previous years provide a good reference for steps in shutdown and start-up. Reading through them with the other members of the management staff will set the stage for a successful winterization. For example, a note from previous years could indicate that it was particularly helpful to winterize the micro-irrigation zones for the landscape beds near the concession stands before moving on to big heads, valve boxes and pipes in the soccer fields. Since they are more exposed and prone to damage, it just makes sense to start with them.
Another way looking back can be helpful is in the hiring of additional staff during winterization. Since the fields can be spread out quite a distance from each other, the details written in previous notes can help determine how many people are required to complete the winterization with efficiency, especially if remote-control technology hasn’t been installed at your facility.
Checking pressure at various points in the winterization process is important to avoid overloading the system.
The heart and soul of winterizing irrigation systems is matching up the size and capacity of the compressor to the needs of the field. A key factor in choosing is to select one with sufficient capacity to move the necessary amount of water out of the components to clear the system without causing damage to the parts. Depending on the number of heads and joints/elbows as well as the length of the pipes, select one that provides sufficient air pressure to remove as much water as possible in a reasonable amount of time. A good rule of thumb is to use a minimum 125-CFM (cubic feet per minute) compressor with irrigation systems that have 3-inch-diameter pipe or smaller. Systems with 4-inch-diameter or larger pipe may require 250 CFM or more. Most industrial rental stores carry 185-CFM compressors for rent. Select a unit with good flexibility for a variety of fittings and connections so that each field in your facility can be blown out with ease.
Watch it run
Just as you would during an irrigation audit, be sure to run the system through a complete cycle to make sure that all heads pop up to expel internal water and that no leaks or broken parts exist. If flaws or defects are observed, be sure to note them for repair during the following year, or, better yet, fix them right away so you know it’s done. Also, consider installing additional drainage valves in low spots in the system to facilitate removal of accumulated waters.
Do’s and don’ts
Remember, it is easier to drain and winterize a system properly than it is to replace components during spring start-up, so be sure to follow these precautions.
- Relieve water pressure on the mainline by activating a zone on your controller.
- Always keep a sprinkler zone open from start-up to compressor shutdown (if not, surges in air pressure of up to 600 PSI can be placed on irrigation components).
- Start at the farthest and/or highest zone possible; water can run down into the main if you start low.
- Avoid exceeding 50 PSI whenever possible. If all heads do not pop up at 50 PSI, gradually increase pressure until all pop up. Never exceed 80 PSI.
- Leave one zone on while shutting down the compressor.
- Consider placing a gate valve between the compressor and the irrigation system (ball valves can create water hammer).
- Do not force air through any backflow prevention devices.
- Do not blow air through any station longer than 2-minute durations. Excessive heat may damage pipe or sprinkler drive mechanisms.
- Do not turn the controller off at any time throughout the blow-out process.
- Do not look down directly above sprinkler heads or valves while under pressure. Always wear eye protection!
- Do not blow out system through the pump. Drain the pump following the blow-out procedure.
In most cases, one cycle is not sufficient to make sure all water has left the system. The best way to know if the job is done right is to repeat each station cycle two or more times or until there is only a fine mist being expelled from the heads or emitters. Depending on the specifics of the notes from previous years, it may be necessary to follow up with another cycle or pressurization of the system a couple of days later just to make sure.
The final touch
After the water supply has been shut down for the season and the system drained, return to the ball valves at the backflow preventer and open and close them several times to remove any water trapped in the valves. Leave each valve handle at a 45-degree angle to reduce the possibility of freeze damage. To help prevent condensation to the electronic controller, leave power on with station start switch and rain switch to off.
John Fech is an extension educator specializing in turf and ornamentals at the University of Nebraska-Lincoln. Brad Jakubowski is a professor of environmental science with Doane College in Nebraska and a diagnostic consultant in the sports turf industry.
Editor’s note: This article was originally published in SFM’s September 2012 issue.