By Luke Frank
Clear the channels now. That’s the best advice I can give you. Turn off the noise, find a quiet room, sit down, plan it and do it. Remember that apathy will bear the bitter fruit of your inaction. You’ll have forfeited your right to complain five months into next year.
I’m referring to blowing out your irrigation system for the season, of course. Ever been the proud caretaker of an ice-splintered piping system? Had the thrill of wrestling a six-inch main or enjoyed the cool comfort of a turf-covered waterbed mattress?
Anybody who’s forgotten a can of beer in the fridge for four months knows the persistence of frozen liquid. The risk of pipe and fitting damage due to incomplete water evacuation is not worth the time you save ignoring the process. Set it up correctly this fall — once and for all — reinvent the process one more time, and each successive fall and spring will be a much faster, more effective transition.
Locate your blowholes
You should be aware of general winterization techniques, as well as any temperamental spots that might require attention for each site, before finalizing a system blowout plan. If your system is not equipped with air inlets, drains and relief valves, retrofit them strategically where they’re accessible and effective.
For example, configure your mainline system so that compressed air can be introduced into the piping at key locations, providing for the prompt, easy removal of the majority of water from the entire mainline system. At the water source, an inlet should be provided just downstream of the backflow preventer as the point of connection for an air compressor hose. Don’t forget to fit your system with drains in system low spots to further facilitate system evacuation.
At your mainline ends, or at isolation points in a looped system, consider burying some quick couplers as additional points of water release. Place them in key locations so that during winterization, high volumes of water can be easily released from the system. It’s important that your quick couplers (and drains) be accessible and, when practical, protected by a valve box.
The perfect storm
On larger projects with multiple taps and looped mainlines, a game plan should be created, documented and followed. Once you get the first true winterization under your belt, the ensuing blowouts will be more simple and effective.
Looped mains will need to be isolated to create single, independent flow direction. Multiple tap systems also will have to be isolated, one tap from another, to form independent flow directions.
Proper compressed air volumes and pressure are keys to successful winterization procedures. Generally, compressed air pressures of 70 to 80 psi combined with air volumes of 160 cfm will service most properly laid out systems. These are key ingredients of your perfect storm.
Larger sites or poorly designed systems might need multiple compressor units to provide the necessary air volume to purge water from the system. You’ll know as the process unfolds. Remember, full air volumes are the key to the best system purging. And be patient — while a simple residential system may take an afternoon, an industrial park or campus could take several days of isolating and purging zones.
To begin the winterization process, shut down the water source, then hook the compressor into winterizing inlets designed or retrofitted into the system. Large volumes of water should first be released through the mainline, making zone-by-zone procedures less time consuming.
Fire up the compressor and let it build up the desired pressure, then go to the end of the mainline and insert a quick-coupler key into the quick coupler. When the key is completely inserted and compressed air introduced, water will begin to flow. Gradually, you’ll see a combination of air and water, then very moist air and water vapor, and finally just air. Mainline purging is now complete.
Now go to the irrigation controller and activate it zone by zone. Repeat the same process looking for the same results. Follow this by locating any manual zones, drip zones, fountain system supply taps, lake fill lines, etc., and perform the same process.
On larger facilities with varied topography, an additional step might be necessary. After your first-round winterization is complete, shut down the compressor and allow the remaining water to “pocket.” Then startup the compressor(s) and purge the remaining water.
Although every irrigation system has its own personality, these general guidelines should get you headed in the right direction. With a plan formulated over an as-built in the quiet comfort of your office, you can tackle the roving enigma of proper irrigation system winterization and look forward to a successful spring recharge five months into next year.
Luke Frank has been an editor and publisher in the green industry for the past 17 years, addressing water resource development, management and conservation through the irrigation profession. His field experience includes 17 years as an irrigation foreman, contractor and manager in the landscape, turf, golf and nursery industries. He currently resides in Albuquerque, N.M., and can be reached via e-mail at firstname.lastname@example.org