By: Tracey L. Kelley
Irrigation system maintenance is a vast topic of discussion—so much so, to do this article, we needed a team of experts to address it—in two parts. Mark Hewitt, the district sales manager for the ag products division of Rain Bird Corporation in Azusa, California, put it this way: “These are huge topics! People write books about these subjects! 1,500 words? Good luck!” Yet we understand it’s essential to initiate an open forum periodically to ask about research, various applications or innovations that might help keep your system—and the entire growing season—flowing smoothly.
In the first part of this story, the experts provide tips for what you may need to know immediately to start operations and remedy any issues. In the July-August issue of The Grapevine Magazine, we’ll feature further concepts and suggestions from our experts.
In addition to Hewitt, other people extending their knowledge include:
- Guy Fipps, Ph.D., P.E., professor and extension specialist of irrigation and water management at Texas A&M University, College Station, Texas; in collaboration with Charles Swanson, extension program specialist, Texas A&M University
- Jacob Hernandez, CCA, owner, JH Ag Consulting, Santa Margarita, California; in collaboration with James Anshutz, AGH20, irrigation engineer with Netafim USA in Fresno, California; and the Cal Poly SLO Irrigation Training and Resource Center, San Luis Obispo, California
- Steve Purvins, owner, The Vineyard at Lawton Hall in Bushwood, Maryland, which produces Vidal Blanc and Chambourcin grapes
Let’s Get It Up and Running
Regionality, post-harvest vine vigor, and winter precipitation are all factors determining whether a vineyard irrigation system gets shut down off-season. Some growers close it all off, while others use irrigation intermittently, but still need to check various components. A few growers know by late March if their vines have delayed spring growth due to insufficient water during colder months, and can only plan for next year to enable better health with a post-harvest irrigation plan. For the majority of producers, it’s time for a spring tune-up. De-winterizing a system follows numerous steps.
Fipps started the process with the basics:
- If the irrigation system was idle all winter, the system should be inspected for any damage that could have occurred. Turn each station on for a cycle and visually inspect each for visible tears or leak in the tubing, as well as dry areas from clogged drip emitters.
- While running, also check the pressures and flow rates—if pressure gauges and flow meters are installed—to ensure they correspond to system requirements.
- It’s also recommended to flush each drip line for a short period to remove any sediment or biologicals like algae that could have accumulated. Flushing the lines can help reduce problems during the irrigation season.
Fipps added, “All drip filters should be removed and properly cleaned before start-up. If any filter is damaged or unable to be cleaned, it should be replaced. Additionally, for automatically controlled systems, make sure all valves are opening and closing correctly. Valve solenoids and diaphragms can become damaged over time, requiring maintenance or repair.”
Hernandez provided a detailed four-part checklist:
- Pump station hardware: start system and make a note of any leaks from broken pipes, couplers and other fittings. Repair and replace as necessary. Exercise manual and automated valves. Clean air vents and replace any damaged units. Check for proper pressure settings of any pressure reducing or sustaining valves.
- Filtration systems: Remove screens and pressure wash to remove debris. Treat with a chemical solution to kill biological slimes, then clean and replace. Check sand media and refill and replace as needed. Sand media should have sharp edges—if rounded, replace. Check settings and function of automated backflush system, and make sure differential across filters is less than 10 psi. A properly-functioning filter station is one of the most critical components in maintaining uniformity of drip and micro-irrigation systems.
- Check your pump flow rates and pressure monitoring systems for each irrigation block or set. If you’re using a variable frequency drive (VFD), schedule an appointment to have the VFD serviced. Check settings and make adjustments as needed based on current conditions that may differ from when the VFD and pump station were installed. Check flow meters and pressure gauges for accuracy and calibrate or replace any damaged or unreadable gauges.
- While the pump is running, check the irrigation set perimeter to make sure all line ends are receiving water and re-attach any disconnected lines. Drive every line to check riser tee screens for debris and clean or remove and replace with plain washers. Check flow rates of emission devices and replace plugged or partially plugged devices as necessary. Check riser tees, couplers and hose ends for leaks, and replace or repair as needed.
“Review the previous season with your irrigation supervisors to understand the most common problems the irrigation team is dealing with,” Hernandez told The Grapevine Magazine. “Plan to fix the biggest issues in a systematic fashion. Often, a simple fix will open up a lot of time for your irrigators and enable them to spend more time on preventative maintenance instead of temporary fixes.”
Hewitt also offered a multi-check process:
- For surface-mounted pump stations, check for leaks, broken or cracked pipes and damaged pressure gauges. Leaking packing glands or bearings need to be adjusted—usually tightened or replaced.
- Examine filter stations. Screens and disc filters need to be pulled and inspected for damage and wear. Media filter covers need to be pulled, and their sand checked for cleanliness and quantity. Add new sand if levels are low and also check backflow restrictor valves if sand levels are low. Clean control water filers, too.
- Water meters, if present, need to be pulled. Paddle or impeller types should be checked for freedom of movement and re-calibrated if needed.
- Clean site tubes, inspect gauges for freeze damage and accuracy and actuate backflush valves one at a time to ensure they open and close completely.
- All electric solenoids need to be checked to ensure they’re in good working order—no swelling of coils, plungers move freely, and plungers pull in when energized and deactivated by the controller.
When asked what issues managers sometimes encounter that Rain Bird representatives help them solve, Hewitt said, “We’re asked to troubleshoot everything from the water source to the figure eights at the end of the drip line laterals. [We help with] pumps, filters, controllers, valves, hoses and emitters. Filters are one of the most common problematic components of a low-volume system, especially if it’s over three years old,” he said. “Another common issue is plugged or low-flowing emission devices. Remember, no dripper will ever be as clean as it was when it came out of the factory!”
Purvins uses above-ground drip irrigation tubing suspended 8 inches high on a trellis wire and run down each vineyard row, spaced 8 feet apart. He has 0.5 gallons/hour emitters every 96 inches, and his system is supplied by a drilled well. Since he doesn’t irrigate during the winter, his startup is simple: “I have underground drain valves that I use to empty the lines before winter. I just check that all valves are closed in the spring before using the system.”
Handling System Damage Due to Excess Water
Northern California’s heavy rainfall in January and February caused some of the most problematic floodings in 20 years. Areas of the Midwest hit by “bomb cyclones” and significant snowfall melt triggered what scientists at the National Weather Service classified as “major to historic and catastrophic” floods. Some parts of the East Coast are still dealing with the effects of extensive rains and flooding from 2018. We asked our experts: how do these weather events affect vineyards and their irrigation systems?
“In Texas, where most vineyards use drip irrigation, flooding likely will do extensive damage to the drip irrigation system and possibly to pumps as well,” said Fipps.
Hewitt agreed. “This will be a new problem for growers with low-volume drip systems. Areas that were under floodwater this winter that have drip tubing with emitters will need to be very diligent during flushing after the flood waters recede—and some of these drip lines may not recover,” he told The Grapevine Magazine. “Excess water and debris could have entered into the exit bath areas of the driplines. If this material is allowed to dry and harden, most likely no amount of line pressure is going to clean this debris out of the emitter exit pathway.”
Hernandez added, “Flooding could damage infrastructure like pumping stations, pipes and laterals (drip hoses). Carefully inspect any affected equipment. Consider strategies for diverting water to prevent damage from future flooding episodes,” he said. “Additionally, my number one concern would be the impact of flooding events on my soil health. How much topsoil did I lose? What was deposited onto my field? Take soil samples at multiple depths throughout the field and start making necessary amendments as soon as possible.”
In part two of our irrigation system maintenance and upkeep article (Grapevine Magazine, July/Aug 2019), these experts share their views regarding ongoing system checks, typical problems often overlooked, monitoring water quality and critter control.
All listed above, plus:
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