Irrigation Systems; operation, maintenance and winterization.
This is the last of a three-part blog series that will introduce you to all things irrigation including basic principles of irrigation systems, laying out a system, and brand recommendations along with handy tips and tricks!
Part 3: Operating, maintaining, and winterizing an irrigation system
During our last posts Basics of Irrigation, and Irrigation Systems; brand recommendations, layouts, and system details we covered the basics of watering your garden with irrigation systems, recommended high-quality irrigation system brands, defined vocabulary and components of an irrigation system, and provided a few of our tips and tricks for self-installation that we learned ourselves over years of experience! This week we’ll finishour blog series on irrigation by covering our notes on irrigation system operation, maintenance, and winterization.
Download your FREE Irrigation Systems Quick Guide
System startup
Prior to initial operation, the whole system should be flushed with open flush valves on exhaust headers to remove all debris in the inline drip tubing. Early in the process of plant establishment, train roots to grow toward the wetted area by irrigating close to or at the soil’s maximum carrying capacity. You can stop overhead irrigation once the roots are established. This typically takes between three to six weeks. Overhead irrigation is essential when germinating seed, in addition to regular operation of the inline irrigation system. The overhead irrigation can be stopped when the seedlings and roots develop.
When establishing sod, run the subsurface irrigation system long enough to reach the soil’s carrying capacity until the roots knit with the soil. Ensure proper contact between the sod and the wetted soil by rolling. Overhead irrigation is recommended to water in the sod and prevent drying out when the sod is first installed; it is otherwise generally not needed. The system should be inspected regularly to verify appropriate water application and adjust irrigation scheduling as required, especially during the first weeks after the installation of any irrigation system
Next steps:
While it may be tempting to finish installation and then immediately dust off your hands and go to reward yourself with a Starbucks drink, it will always pay off in the long run to run a system inspection.
1. Review the installation and ensure the specified components have been installed. Double check row spacing (and for PLD, emitter spacing per specified product).
2. Verify the following are installed and operating without leaks:
• Water source
• Control valve
• Filter, including a specified filter element
• Tubing and connections
• Air relief valves
• Flush valves
3. Run the system for an extended period and observe the pattern of wetted soil. Verify that a consistent pattern is evident on the surface.
4. Measure the pressure at the control valve and at each flush valve. Record each pressure value and note for reference to aid future troubleshooting.
5. Note the current controller schedule per valve, including run time, days per week, and flow (if available).
Maintenance
Flushing: Flushing inline drip irrigation systems is a crucial maintenance procedure. If used, automatic flushing valves help avoid, but may not prevent, particulate build-up.
You should manually flush and visually inspect the system annually, at a minimum. Disassemble or remove any automatic flush valves before flushing manually.
Injectors: Injection systems are relatively inexpensive, provide an easy-to-use way to solve a variety of potential issues, and add great flexibility to the maintenance of inline drip irrigation tubing. For example, mild solutions of chlorine can be applied to treat potential biological growth or water quality problems. Or in another case, an injection system can allow for easy periodic applications of a mildly acidic solution to dissolve calcium deposits left by hard water, which over time restrict or impede water flow.
Winterization:
In areas with freezing climates, winterization ensures the water in a system does not freeze and expand, damaging the system’s components. This should be done by removing water from the irrigation system with a high-volume air compressor. Open all manual flush valves and disassemble all automatic flush valves. Ensure the pressure when blowing out the system does not exceed 50 PSI. It’s the volume of air, not pressure, which effectively removes water.
Note: The pressure regulator installed with an irrigation system will not regulate air pressure.
Irrigation Fun Facts:
Differences in recommended spacing and flow rates are due to the physical properties of soil as related to water movement.
From largest to smallest particle size, soil is broadly classified into sand, loam, and clay. Many people living in the Pacific Northwest outside of coastal areas will have the finest particles = clay.
Particle size affects capillarity: as particle sizes decrease, capillary forces increase. The greater capillary force allows more water movement through the soil in all directions. Lesser capillary force limits the amount of lateral water movement. As more water is added, gravity begins to draw water downward. The downward movement of water due to gravity is greater for soils with larger particle size.
Following these principles, where you have soils with smaller particle size, you can space emitters farther apart because capillary force will draw water farther before gravity pulls it down.
In soils with large particle size, water will almost immediately begin moving downward. Therefore, emitters must be spaced closer together to spread the water through lesser capillary action before it is lost below the root zone due to gravity. Use the following table as a guideline for spacing.
In situations where you are unsure of the exact soil type, or if you know that soils will differ across a site, determine the minimum recommended spacing and the maximum recommended flow rate based on the largest soil particle size present on site to ensure that water is evenly distributed.