As we begin this discussion on proper irrigation system winterization techniques for northern climates, we must identify these areas. They simply are any area of the country that experiences weather conditions that necessitate the removal of water from the irrigation system for a period of time (weeks or months).

Those of us in these areas that contend with winter soil frost line down to 4 feet in depth, have a strong appreciation of nature and its power. Pipes, sprinklers, wires, valves, boxes, etc., all continually "heaved" and moved all winter. Install something poorly in the fall, and it will have to be redone in the spring.

In most cases, there is little we can do to "beat" our weather conditions. However, there is much that can be done to make a system "give" with the conditions.

At this point you might think our discussion will focus on the service contractor, but it won't. It must begin with design. This is the initial key to providing a system that is continually reliable year after year, even with repeated winter abuse.

Any system will usually be designed and installed in the upper 12 to 24 inches of the soil profile. Such systems are in the direct line of fire for winter abuse. Techniques such as "pipe pitching" are intended to direct water flow to the manual drain when opened in the fall for winter removal. If this pipe were truly pitched during installation, it rarely remains that way due to frost heaving after the first season.

If a client is truly guided to have this form of winterization, each fall less and less water will be released as more of it remains in the piping system. This remaining water then freezes and expands to continually, over time, weaken fittings and pipe through fatigue. Each year, system-damage increases and spring-activation costs increase. These comments simply hold true also on systems that have total reliance on manual and automatic drains for winterization. If pipes do not remain "pitched" due to frost heaving, then water never has the opportunity to really get to the drain anyway. Also, once winter frost completely surrounds the drain, it becomes ineffective as it can no longer release water from the system.

Basic fundamentals tell us that if a device or technique is marginally effective, additional system service will be incurred. Adding pieces to the system that may fail, not work as specified, or will produce damage to other components (when poorly operating) should be avoided.

Beginning early in the design stage, a designer must be aware of winterization techniques required for that particular project before finalizing the layout.

For example, mainline systems on all projects are to be set up in such a way that compressed air can be introduced into the system at key location(s) and provide for the easy removal of the majority of water from the entire mainline system promptly.

At the water source(s), just downstream of the backflow preventer, an outlet needs to be designed in so it can be used as the point of connection for the compressor hose.

Now at the end of the mainlines, or at isolation points in looped system design, add in quick couplers to allow for water release. Of course these would be useful for manual watering during the season, but just remember to place them in designated key location so that during winterization, high volumes of water can be released from the system easily. Also, design quick couplers to be placed next to electric valve groupings or in a valve box itself for ease of locating during winterization.

Designers must have practical knowledge and thorough experience in winterization procedures in order to truly be able to design a reliable system that is easy to winterize. Examples are pumping systems that can be designed to require very little winterization when well thought out vs. poorly laid out pumping systems that require extreme winterization procedures. Another example is the study and use of sprinklers, valves, etc. that perform better than others during winterization procedures and during harsh winter months. Poor designs will result in hard-to-maintain/winterize systems. They will not be an asset to clients, but a terrible burden.

Construction techniques must also strongly support the fundamentals of ease of maintenance. No system should sacrifice those tools needed for a long, durable life for the sake of saving a few dollars during construction.

In these climates of heavy frost, building in flexibility is very important. All systems should be installed with some appropriate flexible unit at each sprinkler. Valves should be installed so that valve boxes do not rest on the incoming pipe. Mainlines are to remain completely outside of the electric valve boxes, etc. These comments are based upon providing that extra movement capabilities in a system to allow for wintertime movement.

Contractors need to always place adequately sized (0.75 inches to 1.5 inches) compressor connections near the water source and outlets ----preferable quick couplers at the end of mainline locations as discussed earlier.

By keeping a "quality first" attitude, we also need to reinforce that quality-minded installation means that each component installed will be placed, adjusted and refined. Systems will be easier to winterize and easier to reactivate in the spring. They will reduce service calls to simple spring turn-on, fall shut-down and preventative-maintenance inspections. Yes, this is happening! Service can be minimized through good design and construction.

Contracting firms that insist on using construction techniques that create service due to lack of knowledge or purpose, try to convince the client that break downs and service calls are just all part of the process. These contracting firms are destroying our industry-quality standards and reputation.

It is very important for the quality-minded contracting firms to produce reliable, accurate "as-built" drawings. Clients must be given copies for their files, for reference during site changes, or if another firm was chosen for winterization and service.

Accurate as-built drawings provide information that tells the winterization service crew where to begin and where to end. The drawings also warn them of peculiar issues and how to deal with them. They provide a picture to show that buried drip line or isolated quick coupler around the corner.

As part of the as-built production process, the installing contractor must be willing, in writing, to detail the known needs of the system. If the installing contractor remains under contract, memorizing (which is not reliable) will not be needed to be relied upon. Also if another firm takes over the servicing, all the documentation will be available to give the client the best possible service.

Now with "as-built" drawings in hand, and a well-designed and installed system, the service contractor begins his process. By providing winterization with compressed air, this service firm will usually pull up to the curb and extend the compressor hose to the designated tap provided.

On larger projects with multiple taps and/or looped mainlines, a "game plan" must be thought through and implemented. The overall goal in all cases is to replace the full water volume with equal or greater air volume and push the water out from one point to another. Looped mainlines will need to be isolated to create single independent flow direction. Multiple-tap systems will also need to be isolated, one tap from the other, to form independent flow directions.

Most winterization procedures using compressed air are best addressed by following the above procedures, combined with proper compressed air volumes and pressure. Firms that have been winterizing through this process have found that compressed air pressures of 70 to 80 psi combined with air volumes of 160 cfm will service all residential, small commercial and most properly laid out systems on larger commercial or industrial sites.

Larger sites and/or sites that are poorly designed and installed for winterization require two or more compressor units to provide the air volume needed to purge water from the system. Remember full air volumes are the key to the best system purging. Compressors operating at 70 to 80 psi and providing 160 cfm will winterize most residential systems in one hour or less. A golf course will usually need at least two compressor units and requires up to two days to purge water from the system.

To begin the winterization process, the service crew must first shut down the water source. If it is a metered system, it may be as simple as shutting a valve. On a pump station designed for non-winter removal, it may be the same (shutting a valve) plus shutting off power. In others, it may require suction line removals, hydraulic valve pumping or microchip removals.

Once the water source is shut down, the compressor can be hooked up to the provided location(s). In northern climates, the tap will usually be on the building exterior with a smaller drain tap inside by the water meter. This method allows for compressed air to be directed inside to the meter by the opening of that drain tap and purging of that line from the building exterior to the interior water source. In other cases, if the meter room is accessible from the outside, the air compression hose can be hooked up directly at the drain by the meter. Water will then be purged from the meter (inside) to the exterior.

Next, turn the compressor on and let it build up the desired pressure. Once accomplished, go to the end(s) of the mainline and insert a quick-coupler key into the quick coupler provided (or threaded connection --- remove cap/open valve). When the key is completely inserted, water will begin to flow, then gradually a combination of water and air, next very moist air and water vapor, and finally just air. Mainline purging is now complete. (Time frame varies with system.)

Designs and construction that provide these provision (quick couplers and outlets) will be easily and completely purged in shorter time frames, and in a much more thorough manner. Larger volumes of water are released first through the mainline, making circuit-by circuit procedures less time-consuming.

Next, go to the irrigation controller and activate it, circuit by circuit. Repeat the same process looking for the same results as discussed above. Follow this by locating any manual circuit, drip circuit, fountain system supply taps, lake fill lines, etc. and perform the same process. If additional quick couplers are on site, the same procedure should be followed.

On larger systems with varied topography an additional step is taken. After the initial winterization occurs, compressors are shut down. The remaining water is allowed to "pocket." Later, the compressors are reactivated and the remaining water will be purged.

With the system now purged of water for the winter, you can be assured that the minimal amount of water re-entering the system through sprinklers will not accumulate in volumes large enough to cause damage. Systems that use manual / automatic drains will leave substantial water in the piping. Thus, when water enters through the same sprinklers mentioned above, larger volumes of water accumulate in the piping and freeze damage will occur.

This report outlined techniques that work very well in northern climates where frozen ground and frost heaving are destructive and unforgiving. In areas of the country where frost enters the ground but does not reach the piping systems, the use of drain valves may work sufficiently as a minimal method of system freeze protection. Our designs usually will work toward system purging with compressed air unless site conditions and topography work very favorably to drain the system.

Almost every issue related to irrigation systems, quality and longevity begins with the educational level of our industry. Continue to work to improve services to clients. The more knowledgeable we are about design, products, installation and service, the more satisfied customers will be. As our education level increases, we will make better impressions on water purveyors and municipal inspectors.

In reference to winterization, always strive to eliminate unnecessary service calls. Improving installation processes will in turn improve the system's longevity. True irrigation service then begins to take on the appearance and goals of a preventative-maintenance program.

This is our goal with winterization in northern climates. Prevent future maintenance through proper winterization techniques. Give clients the assurance that they are on the top of the list.