Winterization Now Can Save Money Later

As the days become shorter and temperatures begin cooling, contractors are being hired to winterize irrigation systems.

The winterization of irrigation systems is not a seasonal occurrence only for those living in the northern United States and Canada. This practice should be performed in any region where the frost level could extend below the depth of installed pipe.

Winterization primarily consists of expelling all the water from the irrigation system and equipment. This is necessary because water freezing during cold weather expands, leading to broken pipes, fittings, valves, sprinklers and pumps. According to the Colorado State University Extension Service, most substances contract as they get cold. However, when water cools, it contracts only until it reaches a temperature of 39 degrees Fahrenheit. Upon further cooling to 32 degrees Fahrenheit, water expands as it turns to ice. Water expands and increases in volume by one-eleventh, so 11 cubic feet of water will form approximately 12 cubic feet of ice. This expansion force is sufficient to cause pipes and fittings to burst, valves to crack, and sprinkler and pump cases to split open.

  
Left: Many professionals believe the proper pressure for winterizing an irrigation system is between 55-60 psi.
Right: The ball valves on a typical backflow preventer, or pressure vacuum beaker, should be left at a 45 degree angle after winterization is complete.

John Eggleston of Southfield, Mich.-based Federal Irrigation Supply said his crews began the winterization of private residences and condominiums in early October.

?EUR??,,????'??Private residences only take about half a day, and condo projects take about a day, so the process is not too difficult,?EUR??,,????'?? he said.

The first step in the winterization process is draining the system. This can be accomplished by the use of either manual or automatic drain valves that rely on gravity to drain the water from the system. If electric valves installed on the system, it is difficult to drain the water off the top of the diaphragm of the valve. Manual gravity draining occurs underground, making it more difficult to determine if enough water has been drained to prevent freeze damage. A common method used by contractors to ensure that enough water has been expelled from the system is by using compressed air to ?EUR??,,????'??blow?EUR??,,????'?? the water out.

Pumps or backflow preventers should also be drained. These can then be removed from the system and stored inside. If the pump must remain outside, it can be drained and wrapped to insulate it from the weather. Backflow preventers can be handled in the same way, except that water to the system needs to be turned off. The use of stop and waste valves are recommended because they are designed to drain the water from underneath the inlet of the backflow preventer.

?EUR??,,????'??BLOW-OUT?EUR??,,????'?? WINTERIZATION CHECKLIST

• Don?EUR??,,????'???t allow air pressure to exceed 60 psi (especially in systems designed to operate below this pressure level).
• Don?EUR??,,????'???t stand over component parts while the system is under air pressure.
• Don?EUR??,,????'???t leave the compressor unattended.
• Don?EUR??,,????'???t blow out the system through a pump (first blow out the system,then drain the pump).
• Don?EUR??,,????'???t leave manual drain valves open (water could enter the system during a winter thaw).

George Cole, a technical services representative at Hunter Industries, recommends the use of an air compressor with a maximum of 50 psi be used on residential projects, and a slightly higher pressure for commercial irrigation systems.

?EUR??,,????'??The velocity of the air is not the most important thing,?EUR??,,????'?? he said. ?EUR??,,????'??Having a little water remaining in the pipes is not a problem as long as that water has room to expand.?EUR??,,????'?? If too much air pressure is used, the added friction could heat up the pipe and fittings, which could melt these items. The result would be more problems in the future. Cole said to never shut down an irrigation system during winterization. One valve should be manually left open, and the process should be completed one station at a time. Crews in Calgary, Alberta, Canada began the winterization of city lines in early September. By the next week, snow had fallen, although it melted several days later after temperatures rebounded to the 70-degree mark.

Using a correct air pressure of 55-60 psi will be evident by the mist emitted from pop-up spray heads when the irrigation system is being blown out for winterization purposes.

?EUR??,,????'??We started winterizing in earnest at that time because we don?EUR??,,????'???t know what will happen weather-wise,?EUR??,,????'?? Denis Gourdeau, Calgary water management coordinator, said.

Gourdeau noted that arctic cold snaps are common occurrences for Calgary in late August and early September, necessitating the early start for winterization.

?EUR??,,????'??We have roughly 2,000 systems to winterize, and it usually takes us six to eight weeks to complete,?EUR??,,????'?? he said. ?EUR??,,????'??We have everything from old galvanized systems to fully automated systems.?EUR??,,????'??

Gourdeau said crews will drain all the main irrigation lines where ever possible. Several days later, they go back with air compressors to blow out these lines.

?EUR??,,????'??If we didn?EUR??,,????'???t do this, and had a line break, we could lose our the main line and laterals,?EUR??,,????'?? he said.

Shown here is a typical tow-behind air compressor with a 185 horsepower air compressor engine. The access panel is open revealing the engine of the compressor. The yellow hose is the air hose.

Gourdeau noted that the bulk of Calgary?EUR??,,????'???s irrigation lines are placed 18-24 inches below the surface, which is 100 percent in the frost zone. Eggleston said many of the lines in the Detroit area are also about 24-inches deep, which is the frost zone in southeastern Michigan.

?EUR??,,????'??We do have some older pipes that are located below 24 inches, and they aren?EUR??,,????'???t always winterized,?EUR??,,????'?? he said. ?EUR??,,????'??Unfortunately, last year we had a tough winter of very cold temperatures and little snow, which resulted in the frost zone being deeper than usual.?EUR??,,????'??

Federal Irrigation Supply charges about $60 to have its crews winterize irrigation lines. Eggleston said he recommends that all systems, regardless of depth, be winterized annually.

?EUR??,,????'??Back flow prevention devices cost a couple hundred dollars, and it could cost thousands of dollars to repair and replace damaged pipes,?EUR??,,????'?? he said. ?EUR??,,????'??So winterization is definitely the most cost-effective thing to do.?EUR??,,????'??