Irrigation retrofit improves responsible water use
Responsible water use should be a core principle of every groundskeeper, whether your facility is adjacent to a large reservoir or depends upon a very limited water supply. The plant life under your care requires adequate moisture to fulfill its purpose in the landscape. Even where a plant is adapted to the climate, weather is unpredictable and unreliable. Therefore, irrigation ranges in importance from a type of insurance to a complete necessity.
Ironically, landscape irrigation was born more from the aspect of insurance than from dependence. Wealthy estate owners, including Henry Ford and Harvey Firestone, paid inventors-such as Charles Skinner and John A. Brooks-to develop the earliest sprinklers, valves and controllers for their massive estates. Plants, both nativeand exotic, were important to these industrial barons. They valued their grounds highly and became patrons for the first automatic-irrigation systems.
Dependence strengthened the irrigation industry as people from the East and Midwest migrated to the arid West earlier this century. To meet the demand for eastern landscapes in the desert, Van Thompson, L.R. Nelson, George Moody and others invented sprinklers specifically for landscapes. If it weren't for the Great Depression, landscape irrigation would have filtered down the economic ladder by the 1940s. However, a tremendous resurgence of inventiveness and family home ownership following World War II made irrigation available to the masses, not just the wealthy.
A luxury for the wealthy became a necessity for the homeowner in the Southwest and Southeast. By the 1970s, irrigation systems were standard on homes in subdivisions in arid regions. The flow of technology rebounded toward the East and North as more homeowners depended on two incomes to pay the bills. Automatic control and precision application of irrigation for landscapes became a necessity even in humid regions of the country. Landscape-irrigation-system sales exceeded a billion dollars by the 1980s.
Today, the Irrigation Association (IA) estimates that the percentage of new construction that includes irrigation has reached 65 percent in the Southwest, 40 percent in the Southeast, 5 percent in the Midwest and 2 percent in the Northeast. A recent industry survey revealed that 40 percent of landscape contractors perform some type of irrigation work on a regular basis. Obviously, irrigation is an important part of grounds maintenance as we enter the 21st Century.
Responsible water use The demand for water compared to supply is far different today than when inventors created the first automatic irrigation systems. The future of irrigation depends on maximizing irrigation efficiency. Manufacturers are constantly striving toward greater distribution uniformity, more responsive control and prevention of malfunctions, such as contamination caused by breaks and backsiphonage.
Retrofitting older systems is an essential part of achieving the highest possible efficiency. Advances in sprinkler-head design, controller hardware and software, and sensor/controller communication have enabled distribution uniformities to increase efficiency from the 60-percent range to more than 90 percent. Better uniformity combined with more responsive scheduling are the two most important aspects of irrigation management today.
Uniformity results from proper design and precision of the sprinkler and other application methods, such as drip/trickle and microspray irrigation. Designers rely upon a consistent flow and pressure of water and a soil that has reasonable infiltration, storage and drainage capacities. Based on these factors, they match the application of moisture to the needs of assorted plants with the landscape.
The average landscape requires a variety of application techniques used in several zones or stations. Controllers must offer enough stations to meet the specialized needs of the plants and the various microclimates present at the site. The designer must consider the water needs of the landscape from installation to changes that occur as the landscape matures. Up to eight repeat cycles per day could be necessary for sodded or seeded turf. While runtimes for turf average less than 20 minutes, drip zones might require up to 4 hours.
Controllers must be able to connect with sensors. The city of Cary, N.C., now requires rain sensors on all types of automatic-irrigation systems. Water districts in California are considering test programs for rain and moisture sensors. Several manufacturers have begun to explore ways to feed weather information to controllers so they can adjust irrigation schedules to local weather. Sensors might be optional today, but they might be required in more cities in the next few years. Some cities have "water police" to enforce standards and to reduce waste. Sensors can prevent most of the offenses the enforcers observe. For example, pressure sensors can detect broken heads and pipes and can signal the controller to shut down all irrigation or just a particular zone.
You can easily retrofit controllers. Manufacturers offer controllers with advanced features that are expandable. You can add modules of four zones to many new controllers as needed. Thus, you get the latest water-saving features with the ability to expand irrigation control as the landscape matures.
Another option to consider if you are responsible for multiple controllers is central control. Replace stand-alone controllers with field satellites that can communicate with a central controller either by wire, phone line or radio. You can adjust all the satellites at a computer in one location. Some systems allow you to call the central controller from your home phone or computer to make adjustments.
Also consider hand-held remote controllers. These use radio transmitters and receivers to operate satellites within a certain distance. Two-person irrigation projects become single-person ones with a remote. These are tremendously helpful for troubleshooting-a big part of maintaining irrigation efficiency.
Troubleshooting tips The best-designed irrigation system still faces the threat of vandalism, lightning and changes in water pressure. It is possible to enclose vulnerable pieces of equipment (controllers, backflow-prevention devices and valves, for example), install electrical surge protection on controllers and pressure regulators on pipes, but sprinkler heads and drip emitters will always be exposed to damage and tampering.
To help deter this problem, you can employ sensors to shut down damaged zones and to notify you through warnings on controllers. You also should observe plants for signs of wilt or disease. Even so, you still must inspect your irrigation system on a regular basis. Only the knowledgeable groundskeeper can detect irrigation problems before serious damage occurs.
Troubleshooting often involves an electrical problem, not a water problem. Learn to locate electrical faults in wires. And check the operation of solenoid valves periodically. You might be able to fix a valve by replacing the solenoid instead of replacing the whole valve. Valves that chatter can put tremendous stress on pipes and joints.
Debris in the water frequently shortens valve life. This was part of the reasoning behind the development of anti-siphon valves. Many irrigation systems today use a single backflow-prevention device to protect the water-supply system from contamination by backsiphonage. In these systems, you replace anti-siphon valves with standard solenoid valves. However, in doing so you have protected the water supply, not the valves. Therefore, any time you make repairs, be careful to flush out the pipes before restoring the system to full operation. If you regularly notice dirt or pebbles in the small strainer filters in sprinkler heads, you need to filter your water supply.
Filters are more important than ever. You should use them to protect the backflow device, valves, sprinklers and drip emitters. They range from simple screen filters to disk filters and sand separators. Filters, like all irrigation components, create a friction loss that you must consider so that all heads and emitters operate at design pressure. Keep in mind that booster-pump stations are available for situations of low or inconsistent pressure.
High pressure can be as harmful as low pressure. Pressure regulators are critical for drip-irrigation zones and might be wise for all zones in regions where supply pressure varies considerably.
Keep in mind that retrofitting can expose good designs to new mistakes. If you replace sprinklers, you also should replace every head in the particular zone with the same model. If you reduce pressure or flow, adjust the flow control on the valves to increase flow. Check to see that sprinklers still reach the area intended for their spacing without misting. Place catch cans throughout a zone and run the zone for 10 minutes. The depth of waterin each can should be the same. You often can correct some common problems-such as part-circle heads and heads along windy borders-by changing the nozzle. Keep in mind that fewer sprinklers means fewer problems. Therefore, upgrade spray heads to rotaries where possible.
Of course, sprinkler heads are not always the best solution in situations such as narrow medians, parking islands, berms and steep slopes. Surface and subsurface drip might be a wiser choice in these areas. Keep in mind that pressure control and filtration are also important for low-flow zones.
Reclaimed water and irrigation The debate over who has priority for fresh water has just begun. Experience reveals that cities have clout over agriculture as they grow into rural areas. In the future, however, the debate might shift to be among landscape uses, domestic in-home uses and industrial needs. In some regions, landscape irrigation uses 80 percent of fresh water supplies in the summer. Clearly, the industry should keep in mind the possible use of reclaimed water for irrigation in the future.
This heightens the importance of filtration, integrity and reliability of sprinkler components and control. The use of reclaimed water can alter the type and amount of plant materials used in a landscape. This is because reclaimed water creates new issues with the sodium, metal and biological content of water being distributed over parks, schools, residences, and shopping districts.
Another thought to consider is that, as reclaimed-water use becomes more common and necessary, cities might not allow you access to it if your irrigation system is inefficient, unreliable or poorly controlled. Therefore, those who retrofit their irrigation systems today protect the future of their landscapes tomorrow. Delaying improvement in irrigation systems not only puts you at risk, it sends a negative message to other water users and casts all landscape industries in a bad light.
Bruce Shank handles public relations for The Irrigation Association. For more information on IA programs, call (703) 573-3551 or visit the association's Web site or search engine: www.irrigation.org or www.irri-gate.com.
If you respond yes to more than three of the following items, you should seriously explore upgrading your irrigation system. * Controller's maximum station run-time is inadequate. * Number of cycle repeats on controller is too small. * Number of stations on controller is too small. * Drip/trickle irrigation is becoming more important at the site. * Valves stick or chatter occasionally. * Often find debris in sprinkler filter screens. * Water pressure varies widely. * Vandalism of irrigation components is common. * Temporary or permanent water restrictions have been implemented. * Local irrigation ordinance is being considered.
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