Irrigation Systems; operation, maintenance and winterization.
Week 3 of a 3 part blog series, to introduce you to all things irrigation. Including irrigation system operation, maintenance, and winterization along with irrigation fun facts and handy tips and tricks!
Week 3: Irrigation system operation, maintenance, and winterization
During our last posts Introduction to Irrigation Systems, and Irrigation Systems; system details, layouts, and brand recommendations we 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 our years of experience have taught us! This week we’ll wrap up our irrigation systems blog series with our notes on irrigation system operation, maintenance, and winterization.
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Initial operation
Before the initial operation, all pipes should be flushed with open flush valves on exhaust headers to remove any debris in the inline drip tubing. During plant establishment, you’ll need to irrigate close to or at the soil’s maximum carrying capacity to train roots to grow toward the wetted area. Once the roots are established, overhead irrigation can be stopped. This typically takes from three to six weeks. When germinating seed, overhead irrigation is essential, in addition to regular operation of the inline irrigation system. The overhead irrigation can be stopped when the seedings 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 when the sod is first installed (to water in the sod and prevent drying out) and generally is not otherwise needed. Especially during the first weeks after the installation of any irrigation system, the system should be inspected regularly to verify appropriate water application and adjust irrigation scheduling as required.
Next steps:
It may be tempting to say “Check irrigation installed” I will reward myself with a Starbucks drink. Before you run off please put on your inspector outfit and run a system inspection.
• Water source
• Control valve
• Filter, including a specified filter element
• Tubing and connections
• Air relief valves
• Flush valves
1. Review the installation and make sure the specified components have been installed. Verify row spacing (and for PLD, emitter spacing per specified product).
2. Verify the following are installed and check for leaks while operating
3. Run the system for an extended period and observe the wetted pattern. Verify consistent wetting pattern is evident on the surface.
4. Measure the pressure at the control valve and at each flush valve. Record the pressure 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.
At a minimum, manual flushing and visual inspection of the water is recommended annually. To manually flush a system with automatic flush valves, disassemble or remove the flush valves first.
Injectors: Injection systems are relatively inexpensive, provide an easy-to-use way to apply a wide variety of solutions, and add great flexibility to maintaining inline drip irrigation tubing. Mild solutions of chlorine or acid can be applied to treat potential biological growth or water quality problems. Water with significant amounts of dissolved minerals (hard water) may leave calcium deposits, which over time restrict or impede water flow. When designing for systems with hard water, consider an injection system to allow periodic applications of a mildly acidic solution to dissolve.
Winterization:
In areas with freezing climates, winterization is needed to remove enough water from the irrigation system to ensure freezing and expansion of water do not crack the components. This should be done 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.
In descending order of particle size, the soil is broadly classified into sand, loam, and clay. For many people living in the Pacific NW (not including near the ocean) you 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 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.
For soils with smaller particle size, emitters can be spaced farther apart because capillary force will draw water farther before gravity pulls it down.
For soils with large particle size, water will almost immediately begin moving downward. 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.
If you are unsure of the exact soil type or know that soils will differ on a site, use the minimum recommended spacing and the maximum recommended flow rate to ensure that water is evenly distributed.
