     |
 |
Improving
distribution uniformity can
save golf courses money.
By Kurt Thompson, CID, CGIA, CIC, CLIA
We, the irrigation industry, all believe in the fundamental worth of conserving water. But, let's face it -- businesses are driven by money. As a result, the practical application of conservation strategies by those "in the field" ultimately comes down to economics. For example, on golf courses, one question from golf course superintendents is, "Does improving irrigation efficiency and uniformity affect the operational cost of my golf course enough to go through the effort to improve?"
Let's look at two hypothetical golf courses where the sprinkler uniformity is a typical 60 percent. The effects on annual water use that increasing the distribution uniformity from 60 percent to 70 percent has is shown in the table below.
In the East Coast example, the plants require 15.6 inches of water per year. Because the irrigation system is operating at 60 percent uniformity, the schedule will have to actually apply 20.59 inches of water to make sure the turf in the areas with the poorest uniformity receive the 15.6 inches required for the plant to remain healthy. If the irrigation system can be adjusted so that the uniformity is improved only 10 percent to operate at 70 percent uniformity, then the system will only need to apply a little more than 19 inches per year. It takes 27,154 gallons of water to cover 1 acre with 1 inch of water. Therefore the total gallons needed for the example are calculated by multiplying the Irrigation Water Requirement by the Gallons per Acre Inch times the number of Irrigated Acres. In this example, the water saved by improving the uniformity by only 10 percent is more than 4 million gallons!
If the water source for our example golf course is city water or water purchased from an independent water provider, then the cost of this water savings is simply calculated. Different areas of the country use different billing units for water. Some companies bill in units of 1,000 gallons, and others in units of 100 cubic feet (CCF). If we are to convert our water savings into units of 1,000 gallons, then we divide the 4 million gallons by 1,000 (4,236,024/ 1,000 = 4,236 units).
If the billing units are in CCF, then the 4 million is divided by 748 gallons per CCF (4,236,024 / 748 = 5,663 ccf). At $1.40 per CCF, the efforts to improve the sprinkler uniformity just 10 percent save $7,928.39 per year if it is maintained at peak operating levels.
If the water source for this example is a pump station operating at 1,000 gallons per minute, then not pumping the additional 4.24 millions gallons translates into 70 fewer hours of operation per year. This equals nearly nine fewer eight-hour pumping cycles per year. Saving this wear and tear on a pump station with a life expectancy of 15 years means a life cycle savings of over 1,059 hours or 132 eight-hour pumping cycles. In other words, approximately one free season of pump station operation!
In either case, it can be seen that the greater the plant water requirement, the greater the financial impact of improving the distribution uniformity. The costs to improve and maintain the sprinkler uniformity can be paid for in many cases in the first year.
If the example course was located in a more arid climate with little rainfall, such as the West, the savings from conservation efforts are even more profound. In this example (see table above), the water use and pump station use is 58 percent greater than the East Coast example. At $1.40 per CCF, the water savings means more than $13,700 or more than 122 fewer hours of pump station cost and wear-and-tear.
HOW TO IMPROVE
The above examples show how improvement of an irrigation system can have real, positive impact on a golf course's water use and financial bottom line. So what improvements should be made and how?
Start by giving the irrigation system a general tune-up. Correct the obvious problems such as tilted or sunken sprinklers, spray deflection, rotation speed, missing or broken sprinklers and leaks. The next level of adjustment involves the three factors affecting uniformity -- pressure, flow and spacing. Think of this relationship as a triangle where a change in any of the three elements will result in a change in the uniformity of the sprinkler. The irrigation system needs to be tuned-up and maintained to ensure that all three are correct for the area being irrigated.
Pressure control for high pressure is included as a standard feature in most modern valve-in-head sprinklers or zone valves for bloc systems. If the pressure is not regulated at the sprinkler or zone valve, high pressure can cause the water to atomize as it leaves the sprinkler. This will allow the water droplets to drift uncontrolled, shortening the distance the sprinkler can distribute the water. Pressure regulation prevents problems from high pressure, but it does nothing to prevent or compensate for low-pressure problems.
Low pressure does not allow the stream of water leaving the sprinkler's nozzles to break up into enough small droplets. The result is poor water distribution in the first 10 to 25 feet from the sprinkler. A low-pressure problem is usually a result of overtaxed or leaky hydraulics, or an older pump station. An improperly maintained pump station can, over time, lose the ability to produce the pressure it originally could and, more importantly, not deliver the pressure that the irrigation system was designed around.
Leaking pipes can cause a loss of pressure that also affects the sprinklers performance. But the two most common causes of pressure loss are the addition of sprinklers to pipe that is not of a size that can handle the additional flow and the operation of more sprinklers than the section of pipe can handle.
The element of flow is controlled by both the nozzle size and the pressure supplying it. The nozzle selection determines the flow of the sprinkler. The nozzle can be changed to match the flow of the nozzle to the soil conditions. This will allow altering the flow for a specific area without creating a problem in the other areas being covered by multiple sprinklers operating at the same time.
The nozzle selection and the operating pressure for the sprinklers determine sprinkler spacing. (Refer to the manufacturer's recommendations for specific spacing guidelines.) The spacing for sprinklers operating in one area (i.e. a fairway, green or tee) must be consistent to maximize uniformity. The greater the variation in spacing from one sprinkler to the next, the lower the uniformity.
Once the system has been tuned-up to ensure the sprinklers are in proper working order and are operating with the correct nozzles, receiving the right pressure, and are spaced consistently, an accurate irrigation schedule can be created and implemented. The only element left to put into place is the ongoing maintenance program.
It should go without saying, but if a golf course is going to go to the effort to adjust the sprinklers and then build a precise irrigation schedule, the last thing that should happen would be to let the system operate at anything other than peak performance by neglecting necessary maintenance.
Both training programs and a national certification program exist to help golf course superintendents and irrigation professionals learn how to improve the operation of golf course irrigation systems. Whether your course is in an arid western state, or the humid east, the Irrigation Association and the Golf Course Superintendents Association have partnered to create a nationally recognized program called the Certified Golf Irrigation Auditor.
This is a one-and-one-half-day class that teaches the techniques to measure a sprinkler system's uniformity, as well as develop and implement a base schedule.
There is an exam on the second half of the second day of the program that will net the student the national certification when passed.
Contact the IA offices at 703-536-7080 or visit irrigation.org/education to get complete details and the schedule for classes.
|
Distribution Uniformity Proper scheduling is the essence of good water conservation. Scheduling has four elements -- climactic conditions, turf water needs, soil type and condition, and the performance of the irrigation system. Superintendents are well educated on the basics of the first three elements. What is often underestimated is the understanding of the importance of the fourth element and how significantly it impacts the operating costs of irrigating a golf course. The performance of the irrigation system is not just what is conventionally defined as the maintenance of the irrigation system so that the sprinklers can pop up, apply water, and pop down. Even though this might be all the superintendent has time to do, this level of maintenance does little to achieve the financial rewards of good scheduling. The sprinklers must be able to apply the water to uniform depth. The critical element in a water-conserving irrigation schedule is the uniformity of coverage by the sprinklers. Sprinkler uniformity is a measure of irrigation efficiency and is defined as the relationship of wet areas to dry areas, expressed as a percentage. The method of measuring sprinkler uniformity (used by the Golf Course Superintendents Association and the Irrigation Association) is called the Distribution Uniformity (DU). A DU of 100 percent would mean that the entire area was receiving exactly the same depth of water. However, 100 percent uniformity is not possible because the environmental influences are too dynamic to allow this to happen anywhere other than in a laboratory. Historical averages show uniformities on golf courses range from 55 to 85 percent. |
|
Why Conserve With Surface Water? One might ask, "If my irrigation water comes from a lake or pond, why do I need to worry about water conservation?" Even though there are no direct costs for the water, there are several indirect costs associated with using surface or well water. Pumping Cost Control. If you are pumping water, then you are changing electricity into moving water. This has a couple of costs that are simple to identify and measure. The cost of the electricity is the most obvious. The less a pump runs, the lower the electrical bill. Good water efficiency translates into fewer operating hours, resulting in actual savings from those efficiencies that can be easily calculated. No matter how little you are currently paying for power, most people will agree that cost per kilowatt is not likely to go down, making it a worthwhile investment today rather than tomorrow. An important but less tangible cost is that of maintenance and the wear on the pump station. Again, the amount of maintenance required by a pump station and how long it lasts is directly proportional to the amount of time the pump operates. Running a pump less frequently due to better watermanagement will reduce the frequency of maintenance (and therefore the cost of operation) and extend the life of the station. Control of Leaching and Runoff. The washing of fertilizers and organic materials into the lake or pond by the irrigation water complicates Lake management. (It is food for the algae!) Proper water management can assist in the control of runoff into any type of surface water. Positive PublicAwareness. The non-golfing public regularly targets golf courses with environmental concerns. Through comprehensive water conservation efforts, a course can build a public image as being a steward of the environment. Becoming a proactive member of the community in regards to the environmen can have incalculable benefits. |
The author is a supervising instructor for the Irrigation Association and works for Hughes Supply, Inc. as the national irrigation product manager. He may be reached via e-mail at kurt.thompson@hughessupply.com.
- Back
to the Top -