Putting Irrigation Systems to Bed for the WinterJEFF ULEMAN, PRESIDENT, ULEMAN ENTERPRISES INC.

As temperatures drop towardfreezing in many areas, it is timeto get irrigation systems ready

for their "winter sleep." Systems must becompletely drained and shut down to pre-vent damage caused by freezing water onthe system components. Similar proce-dures are followed for new installationsand for repairs that require system drain-age.

Getting StartedUse a two- or three-person team to

winterize an irrigation system. One per-son must constantly watch the system toensure that all heads spray air during theblowing out procedure.

Always keep safety in mind. To pre-vent injuries, keep all personnel fromstanding directly over any commercial orlarge turf sprinkler as it is activated. Neverattempt to disassemble the system whileit is under pressure.

Serious damage can occur to systemcomponents if improper methods are used.The following general winterization stepsapply to large park, athletic complex, andgolf course irrigation systems. However,it is wiseto review the instructions for yourown system before tackling these proce-dures. For first-time winterization, checkwith an irrigation specialist on any par-ticular concerns. Often, an irrigation spe-cialist will provide a hands-on learningsession.

Backflow Device ProtectionThe most sensitive part of the irriga-

tion system is the backflow preventer. Ifthis device is exposed to freezing weatherconditions, it must be covered or drainedbefore freezing temperatures arrive. Whentemperatures fluctuate, with a few colddays scattered among relatively mild ones,temporary covering of a backflowpreventer with heat-keeping materialssuch as straw may keep it warm enough

. to protect it from freezing and cracking.'On many commercial installations,

backflow preventers are kept within aheated building for year-round protection.

I 2 • DECEMBER 1999

Any system in an area withfreezing and below freezing

temperatures during thewinter is susceptible to

damage from the cold. Themost sensitive part of anirrigation system is the

backflow preventer.

If the backflow preventer is in a buildingthat is not heated, it must be monitoredclosely. When in doubt over the degree ofprotection to provide, winterize. It onlytakes a hairline crack to completely de-stroy a unit.

Step-By-StepFor complete winterization, first tum

off the water by closing the main watersupply valve.

If the system has automatic drains, usethem to evacuate water. If the system doesnot have automatic drains, it must be"blown out" with compressed air from anair compressor. Keep the pressure regula-tor adjusted to 50 psi or less. Higher pres-sures could damage pipes and connec-tions.

To achieve the volume of air necessaryto blowout large systems, you may needto use two or three air compressors with185 cubic feet per minute capacity. Forlarge irrigation systems, a high-volume aircompressor will be needed. Excessive heatwill be generated at the point of air con-nections to the system. To avoid damageto PVC piping systems, use a length of 1-1/2- or two-inch galvanized pipe to dissi-pate the compressor heat prior to enter-ing the irrigation system piping.

Air connection points made at the high-

est locations on main lines will permitwater removal by air volume (CFM) asopposed to pressure (psi). Set the psi atthe lowest possible pressure that will ad-equately remove water from the system.

Open drain valves and/or quick couplervalves at the far end of the system. Whenall water has been drained, leave the drainvalves open and remove the quick cou-pler. Then, tum on one valve in the sys-tem, activating it manually from the con-troller. If it doesn't activate, more air isneeded. The heads should operate just asthey do when the system is watering.While the valve .is turned on, the headswill begin to blow air instead of water. Inthis manner, evacuate water from one heador zone at a time, starting with the headsclosest to the compressor. Electric valve-in-head and hydraulic normally-closedsystems require a minimum air pressureof 35 psi at the head to activate the valveand may require additional time to open.When all of the heads blow air, tum offthe valve and move to the next valve.

After the entire system has been clearedof water, repeat the process to ensure allwater has been evacuated from the sys-tem. This eliminates any pockets wherewater may have settled during the firstevacuation process.

Next, insert the key into the quick cou-plers and blow them out as well. Then takethe air compressor off the system.

Remove the backflow preventer andtake it inside to a warm spot, or open allthe vents and all the ball valves so theyare one-half open and one-half closed. Thetolerance on the ball valves is so tight thatit can trap water between the ball and valveassembly. Though the amount of waterthat collects during the running of the sys-tem may be extremely small, the toler-ances are so close that a little bit of waterwill expand as it freezes and cause cracks.

Within the system, there will be a drainlocated just beyond the shut off valve. Easethe drain open after the system has beendrained. If the shut-off valve malfunc-tioned, even a small trickle of water couldrefill the system over a period of time. This

accumulation of water could freeze,cracking the system, without the problembeing noticed. If the drain is left open, anyleak will be apparent.

Next, check the controller. Many con-trollers are equipped with head resistorsdesigned to generate heat within the tim-ing mechanism compartment. In most ar-eas of the country, this head will preventcondensation and rust formation duringwinter shutdown. If this is the case, leavethe AC power on at the controller and dis-able the timing mechanism by placing theswitch in the manual position.

For controllers without heat resistors,it may be sufficient to simply tum themoff, depending on the conditions where theunit is placed .:Because no water passesthrough controllers, it is not necessary toprotect them from freeze-thaw cycle, justfrom condensation. Check with an irriga-tion specialist to ensure proper proceduresfor "winterizing" your controller.

Hot Tips for the ColdDon't try to rush the winterization proc-

ess. The steps must be completed in theproper order.1) Take precautions. Be on the lookout forthe most common problems.2) Make sure all quick couplers are com-

pletely blown out. Find all hidden couplers.3) Leave the drains open. Leave thebackflow devices one-half open. .4) Act early in the season. Taking care ofa backflow device after the first unex-pected freeze is too late. If a system can'tbe adequately prepared before the firstfreeze, another alternative is to run it.Moving water can take far lower tempera-tures without freezing.5) Underground systems have more built-in natural protection than above groundsystems. Because the ground retains heatmuch longer than the air, it takes an ex-tended cold period for soil temperaturesto drop to the danger level. Still, any sys-tem in an area with freezing and belowfreezing temperatures during the winter issusceptible to damage from the cold.Winterizing is your system's bestdefense .•

- sportsTURF (Adams Business Media),Volume 9, No. 10, OctoberlNovember 1993

Editor's note: Jeff Uleman is president ofUleman Enterprises, Inc., in Elkhorn, NE.He worked closely with National SportsTurf Managers Association board mem-ber Jesse Cuevas on the design and instal-lation of the irrigation system forRosenblatt Stadium on Omaha, NE.

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SPORTS TURF MANAGER • 13