Step-by-Step Guide

Monitoring Soil Temperature to Determine Winterization Timing

One of the most critical aspects of winterization is timing it correctly. Rather than relying solely on air temperature or the presence of snow on the ground, use soil temperature data to make informed decisions about when to winterize your system.

A soil moisture sensor with a built-in temperature sensor provides accurate data about what's happening at pipe level. The temperature sensor is located in the black bi-coded portion of the device, while the blade portion collects moisture data. By monitoring soil temperature trends over a 30-day period, you can identify dramatic temperature drops that indicate it's time to winterize.

For example, a site might show soil temperatures ranging from 83 degrees at the high end down to around 62 degrees, then experience a dramatic drop when a strong cold front moves through. These sudden drops—sometimes occurring over just a two-day period—are clear indicators that winterization should be performed immediately.

Snow on the ground doesn't necessarily mean disaster has already occurred, but it's a strong indication that freezing conditions are imminent and action needs to be taken.

Shutting Off the Water Supply

• Close off your water supply at the meter, ball valve, or supply line connection point.
   
• If your system uses a tank, shut down the tank supply.
   
• Shut down your backflow preventer or backflow prevention device, whether it's an RP (reduced pressure), dual check, or other type. 
    This step serves two purposes:
  • It stops the water supply 
  • Prepares the system for the blowout process.

Blowing Out the Lines

The blowout process removes water from your irrigation lines to prevent freeze damage. This requires specific equipment and a careful procedure to avoid damaging system components.

Equipment Requirements

Use a high-volume, low-pressure air compressor for blowing out irrigation systems. A tow-behind air compressor is the most commonly used equipment. The compressor should provide high volume but maintain pressure at no more than 50 PSI.

The reason for this pressure limitation is critical: air is compressible, but water is not. If you use too much air pressure, it will compress behind the water and then accelerate the water when released, creating water hammer damage that can harm system components. The goal is to move water out of the system and replace it with air, not to compress the air.

For most systems, a 185 CFM compressor is commonly used. On large jobs with extensive mainlines, you may need two compressors running simultaneously to generate sufficient volume.

Connection and Blowout Procedure

1. Connect your air supply source after the backflow preventer or backflow prevention device, but before the first valve. Do not connect through the RP or dual check device itself—the ports are too small and you risk damaging the device.

2. Activate the first zone at the controller before turning on the air compressor. This is essential because you don't want to compress air in the system—the valve should already be open when air begins flowing.

3. Turn on the air compressor and slowly ramp up the air flow.

4. Run the zone until you see water transition to mist spraying from the heads. This indicates that the majority of water (approximately 90%) has been removed from that zone.

5. Move to the next zone and repeat the process.

6. After completing the last zone, shut off the compressor first, then shut off the zone. Never leave compressed air in the lines.

Using BaseStation for Efficient Blowout

The BaseStation 3200 controller offers multiple approaches to streamline the blowout process:

Mobile Access Method: Use your phone or mobile device to activate zones one by one as you move around the site. You can turn zones on and off remotely, and mobile access even allows you to run multiple zones simultaneously if needed.

Dedicated Blowout Program: Since the BaseStation 3200 provides 99 available programs, create a dedicated blowout program specifically for winterization. Set the run times for each zone and let the program run automatically while you walk the site to visualize and verify that water is being properly expelled.

An important consideration: irrigation programs are typically set up based on plant type and microenvironments, not in the hydraulic order of your system. Running zones 1 through 50 in numerical order may not move water through your infrastructure efficiently. When setting up a blowout program, arrange the zone sequence to move water progressively through the hydraulic system from the beginning to the end, rather than jumping around between different areas.

Protecting Above-Ground Devices

All devices located above ground are susceptible to freeze damage and require protection. Even a small amount of trapped water can cause significant damage when it freezes and expands.

Backflow Prevention Devices

1. Drain all water from your backflow prevention device, whether it's an RP, dual check, or other type.

2. Position all test ball valves to the part-way open position. This is critical because even a one-inch or two-inch ball valve contains approximately a tablespoon of water. If the ball valve is left in the closed position, that small amount of water will freeze and crack the brass body of the preventer.

Freeze damage to backflow preventers can occur quickly. Even a single night where temperatures drop to 18 degrees for just a couple of hours can crack a closed ball valve and open up the brass body.

Other Above-Ground Components

Protect all other above-ground water supply components, including hose bibs and any exposed piping or fittings.

Protecting Pressure Transducers

Flow sensors installed in the ground are not susceptible to freeze damage and require no special winterization. However, pressure transducers require careful attention based on their installation orientation.

Upright Position (Preferred): If the pressure transducer is installed in the up position—with the transducer at the top of the tee or device and pointing upward—it will be fine after the blowout process. Any residual water will drain away from the transducer.

Inverted Position: If the pressure transducer is installed in the down position (inverted), it will collect water. The small amount of residual water will freeze and damage the device. In this case, you must remove the pressure transducer for the winter.

Horizontal Position: If the transducer is installed horizontally (sideways), you're taking a risk. The recommendation is to treat it the same as an inverted installation and remove the device for winter.

The preferred installation method is always upright, as this eliminates the need to remove and reinstall the device each season.

Inspecting Valve Boxes and Electrical Connections

Winterization provides an excellent opportunity to inspect valve boxes and address potential issues before spring.

1. Open valve boxes and inspect all wire splices.

2. Check that splice connections are oriented with points facing upward. Points-up orientation prevents water collection at the splice.

3. If you find splices with points facing downward, note them for correction. Downward-pointing splices create collection points for moisture, whether from current conditions or spring runoff. This moisture intrusion will cause electrical system problems later.

4. Document any poor-quality or deteriorating splices that need replacement in the spring.

Backing Up Controller Programming

Since you won't be visiting the site for several months, winterization is the ideal time to back up your controller programming and configuration.

Backup Methods

You have two options for backing up your BaseStation controller:

BaseManager Backup: If your controller is connected to BaseManager, perform a backup to the cloud-based system.

USB Drive Backup: For standalone controllers not connected to BaseManager, use a USB drive. You should carry a USB drive with you during winterization visits. A single USB drive can store backups from multiple controllers because each controller has a unique serial number that keeps the files organized.

Why Backup Is Critical

Many controllers in the field are 10 or more years old, and a high percentage are not connected to BaseManager. Unusual events can occur during winter months that may cause catastrophic controller failure. For example, a snowplow could strike and destroy a controller. Without a backup, you'll lose all programming, configuration, zone assignments, and sensor information, creating significant additional work in the spring.

Communicate the value of this service to your customers. Backing up the controller protects not just the irrigation programming but also the system configuration, zone assignments, and all sensor data—information that would be time-consuming and costly to recreate.

Updating Controller Firmware

Winterization is an opportune time to check and update the firmware version on your controller. Since you're already on-site and have backed up the programming, updating firmware ensures the controller will have the latest features and fixes when it's reactivated in spring.

Turning Off the Controller

After completing all winterization steps, turn the controller off but leave it powered. The controller should remain connected to power throughout the winter, but it should not run any irrigation programs.

Method 1: Dial Position Off

1. Turn the controller dial to the Off position.

Advantage: This method ensures that no one can remotely turn the controller back on. The dial position in the field overrides any remote commands.

Disadvantage: When you're ready to reactivate the controller in spring, or if you need to run it for any reason during winter, you must physically return to the controller, unlock it, open it, and turn the dial back to the Run position.

Method 2: Remote Off via BaseManager

1. Access the controller through BaseManager.

2. Set the controller to Remote Off status.

Advantage: This method provides maximum flexibility. You can turn the controller back on either at the controller itself or remotely through BaseManager, without needing to make a site visit.

Disadvantage: If multiple people have access to the controller through BaseManager, someone could inadvertently turn it back on remotely.

Choose the method based on your access control needs. If you're the only person who will ever access the controller, Remote Off provides the most flexibility. If there's any chance someone else might accidentally activate the system, the dial position method provides assurance that the controller cannot be turned on remotely.

Collecting Data During Winter

Even with the controller turned off, you can continue collecting valuable data throughout the winter months. The controller will gather the same data as during the growing season, including electrical checks, moisture data, temperature data, and information from any other connected devices.

Agronomic Applications

Winter data collection serves several agronomic purposes:

Dormancy Monitoring: For cool-season grasses, dormancy typically occurs around 50 degrees soil temperature. By monitoring soil temperature through fall, you can observe exactly when grass moves into dormancy rather than guessing based on air temperature or calendar dates.

Spring Awakening: In spring, continue monitoring soil temperature even before turning the water back on. This provides a "microscope into the soil" showing both moisture and temperature conditions. You can observe when turf begins to wake up from dormancy, which varies by year and location—it might be May 5th in a late season or April 5th in an early spring or warmer region.

Pre-Emergent Timing: Soil temperature is a critical indicator for pre-emergent herbicide application. If you wait too long based on calendar dates or air temperature, weeds will already be present and you'll need to use post-emergent treatments instead. Soil temperature data ensures proper timing.

Fertilizer Application: Similar to pre-emergent timing, soil temperature helps determine optimal fertilizer application timing based on actual root activity rather than assumptions.

Using actual soil data to make these decisions is far more accurate than relying on air temperature or predetermined schedules.

Winter Irrigation Needs

In high desert and arid regions, evergreens sometimes require water during winter months. Use your moisture sensor and temperature data to determine if you need to dispatch a water truck to apply supplemental water to evergreens, rather than making unnecessary trips or allowing plants to become stressed.

Taking Notes for Spring

Document issues and observations during winterization to create an action plan for spring startup.

Items to Document

Splice Repairs: Note any poor-quality or improperly oriented splices that need attention. Even if they're not currently causing problems, addressing them in spring prevents future issues.

Pressure Transducer Repositioning: If you had to remove a pressure transducer because it was installed in the down or horizontal position, note that it needs to be reinstalled in the upright position in spring. This eliminates the need to remove it during future winterizations.

Pending Repairs: Document any repairs or maintenance items you didn't have time to address during the winterization visit.

Firmware Updates: If you weren't able to update the controller firmware, add it to your spring startup checklist.

Using Temperature Sensors to Prevent Ice Hazards

If you're still irrigating late in the season because plant material hasn't gone dormant yet, but you experience a sudden cold snap, irrigation can create dangerous icing conditions on sidewalks and paved surfaces.

Prevent this hazard by using a BaseStation air temperature sensor with a stop condition:

1. Install an air temperature sensor connected to your BaseStation controller.

2. Configure a stop condition in the controller that prevents all irrigation when air temperature drops below 35 degrees.

3. This automated protection prevents the controller from running when freezing conditions would create ice on walkways and other surfaces.

If this situation caught you unprepared during the current season, add it to your notes and wish list for next year. Installing the temperature sensor and configuring the stop condition before next fall will prevent the problem from recurring.

Adding Value to Your Winterization Service

For contractors, winterization can be either a basic commodity service or an opportunity to provide additional value that differentiates you from competitors.

A basic winterization might consist only of the blowout procedure. However, by incorporating additional services—such as opening valve boxes to check splices, inspecting and protecting devices, backing up controller programming, updating firmware, documenting issues for spring, and providing data-driven recommendations—you can increase the value of your service and justify premium pricing.

Document and communicate these value-added services to your clients. Many of the items covered in this guide require minimal additional time on-site but provide significant protection and planning benefits that clients will appreciate.

Warranty Considerations

It's important to understand that freeze damage is not covered under the BaseStation warranty, even though the controller carries a 10-year warranty. Unlike lightning damage, which can be prevented with proper surge protection devices, freeze damage is preventable through proper winterization procedures and is therefore considered a human responsibility.

Proper winterization protects your investment in irrigation system components and prevents costly spring repairs.

Video Walkthrough

Video originally published September 2020.

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