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Weathering the Winter

Some products and basic tips for winterizing irrigation systems

To prevent water stress and potential freeze damage during the winter months, it is important to eliminate or minimize irrigation of turf, lawns and plant material.

If the system has been shut down for the winter, one generally needs to use a great deal of finesse when letting water back into the system in the Spring. A widely accepted velocity is two feet per second. Adjust the valves slowly so the sprinklers rise gradually and emit a steady stream of water - not a sputtering spray, which is the result of letting water in too fast.

Rain-Stat® is a shutoff sensor made by Weather-matic, based in Dallas Texas. When the rain cup accumulates 1/4 inch or more of rainfall, the sprinkler system switches off. The controller then resets itself and resumes sprinkling on the next programmed operation after excess water evaporates.

• Rainfall evaporates through an absorbent ceramic wick at a rate dependant upon air temperature, humidity, and wind-the same factors that affect the loss of moisture in turf.

The Watermark sensor and Watermark Soil Moisture Control System manufactured by Irrometer of Riverside, CA, measures moisture levels in the soil through tension and prevents watering when adequate soil moisture is present.

•There is no need to continually reprogram controllers with the Watermark System because once the sensors are wired into the irrigation system, it is best to set the controller to water everyday. This means the soil moisture sensors are "asked" daily if irrigation is needed.

Hunter Mini-Clik II rain sensor, now manufactured by Hunter Industries, Inc. after their recent purchase of Glen Hilton, measures rainfall and prevents sprinklers from coming on during or after rainfall.

• During rainfall, hygroscopic disks soak up water and expand to depress a switch that breaks the circuit from the controller. After a rain, the disks dry out at a similar rate as the turf. Once the disks are dry, they contact and release the switch. Then the controller system returns to its normal watering cycle.

Hunter Industries also offers:

• The Hunter Wind-Clik, a wind sensor that shuts off sprinkler systems during high winds, which waste water and make a mess of surrounding areas.• The Hunter Freeze-Clik model 401 prevents irrigation systems from activating when the outdoor temperature drops to near freezing.

The HunterMini-Weather station, now manufactured by Hunter Industries after their recent purchase of Glen Hilton, incorporates the Mini-Clik II, Wind-Clik and Freeze-Clik. It offers the benefits of each different sensor in one easily mounted unit.

In a sprinkler system, the sprinkler head is one of the most important parts. As you are well aware, it determines the ultimate and long-term performance of a system because it is, quite simply, the component that actually distributes the water.

This being the case, specific steps should be taken to protect sprinkler heads, particularly if you work in areas prone to freezing or where changes in the temperature can vary greatly, either through the course of a day, or from year to year. Since the global climate is changing and regional temperature fluctuations are becoming more severe and sometimes unexpected, here are some basic refresher tips on winterizing an irrigation system you might find useful.

Sprinkler Heads

One way to protect against freeze damage to sprinkler heads is to install automatic drain valves in each zone of irrigation. Installed below the heads at low points in the pipe lines, the drain valves release the excess water when the system is not running. Hence, no frozen water can burst the pipes or other components.

If the sprinklers have both side and bottom pipe inlets, and the side is being used, install a drain valve on the bottom inlet to prevent the case from freezing. Sprinkler heads containing built in check valves to prevent low head drainage require disassembly, or must be blown out with air to achieve proper winterization. (These types of heads are usually used only on commercial installations.)

It's a small thing, maybe too small to be a real concern for some. The replacement of some sprinkler heads might seem like no big deal. But consider some of the potential costs of sprinkler head damage, a lot of which can fall on your clients:

• Broken heads and system leaks can compromise the rest of the irrigation zone, which, if not functioning properly, can damage the entire landscape. The repairs could end up being a substantial/additional cost to the client who probably expected the work to be "done right" the first time.

• Water discharging from a broken sprinkler head can be substantial and a lot residents pay for their water by the gallon.

• If water leaking from a broken head wets a public walkway, like a sidewalk or a road, in creates a liability issue which could end up costing you or the client a lot of money in a lawsuit.

Winterizing the Sprinkler System

Another way to protect against freeze damage is to winterize the sprinkler system. In addition to protecting the sprinkler heads, special attention should be given to removing water from the pipes and valves. This can be accomplished in two ways: via air compression or drain valves.

Air Compression Method

As a general rule, use the air compression blow-out method in areas where freezing affects the soil more than 1 foot deep. The first step is to close off the main water-supply valve. Next, hook up an air compressor to the fitting downstream of the main water-supply valve. Then start each automatic valve manually from the controller, leaving each valve open until all the water is expelled from the zone. Generally, it is recommended not to exceed 50 psi of air pressure in a system.

It is also extremely important that the air compressor's cubic feet per minute (cfm) rating is appropriate for the sprinkler system, otherwise you could send a pocket of water through the pipes with such velocity it could blow a sprinkler head off.

A more comprehensive list of instructions detailing the process is available through the Rain Bird customer support center at: 1 (800) RAIN-BIRD.

Drain Valve Method

As for the drain valve method (either manual or automatic valves), this is generally used in areas where freezing affects the soil less than 1 foot deep. If utilizing an automatic valve, which opens every time the system is shut off, it is important to provide adequate sump (gravel or other drainage material) to collect the drained water and prevent back-flow of debris that can clog the system.

In the case of manual drain valves, simply leave them in the open position for the winter. This prevents possible re-pressurization. Any diaphragm style valves should be disassembled and drained by removing the bonnet, solenoid, and diaphragm assembly. Sponge any standing water, then reassemble.

Spring Start Up

When letting water back into the system, one generally needs to use a great deal of finesse. A widely accepted velocity is two feet per second. Adjust the valves slowly so the sprinklers rise gradually and emit a steady stream of water- not a sputtering spray, which is the result of letting water in too fast.

A word of caution. If the zone is turned on and the valve is opened all the way, the compression of air remaining in the pipes can boost the pressure as much as five times and send sprinkler heads flying!

Pumps & Timers

Winterizing timers and pumps for sprinkler systems may require special attention. Always consult the manufacturer for instructions if you are unsure.

Automatic Shutoff Devices

Whether or not you work in an area where seasonal rains are frequent, rain shutoff devices are recommended because water conservation is important. In some cases it is required by law, in most others it is simply a practical matter- too much water can stress turf, lawns and plant material.

Although rain shutoff devices vary a great deal, most of them can be put into one of the two following categories: the rapid-response shutoff and the preset shutoff.

Rapid-Response Shutoff

The rapid-response shutoff (as you may have already guessed) senses rain almost immediately, shuting the irrigation system off in case it is running. In addition to saving the landscape water-stress or contributing to any drainage/erosion control problems, it will keep your public image looking good. Clients or the general public in your area could get particularly irate about water being wasted.

Preset Shutoff

The preset shutoff works on the basis of adequate site watering, either by rainfall or irrigation. When the plant or turf/lawn water need is met, the system is kept off until a sensor-unit registers a need for more water.

One disadvantage to this type of shutoff device can be that rainfall and irrigation can happen simultaneously, until the preset water amount is reached. Another disadvantage can be some sensor-units hold water, a definite concern in climates prone to freezing. Be sure to consult with the manufacturers to see if they have addressed these issues in their products.

Other Seasonal Considerations

Irrigation Specialist Michael J. Schmitt of Environmental Care, Inc., in Calabasas, CA recommends that Landscape Contractors and maintenance companies take advantage of the slower seasonal months to work on employee development. Schmitt says it's a great time for training and planning for the following year. If there aren't in-house training opportunities for continuing education or certification programs, many Universities offer irrigation training, such as Cal Poly Pomona in California. Another place to advance your knowledge of the trade is through the Irrigation Association of America and companies like Rain Bird® who offer seminars.

But always remember, no matter where the opportunities are take advantage of them. Employees are some of the most valuable assets to any company. Help them grow and they'll help you grow. lcm


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June 27, 2019, 2:06 am PDT

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