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Features Agronomy
Where’s the green? How can auditing an irrigation system give you insight


February 11, 2009
By Lorne Haveruk

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  Measuring green prior to laying out catch cans to measure applied water.
While auditing an irrigation system, watching the water being caught by the catch cans laid out in a 15-foot-by-15-foot grid pattern or close to the sprinkler head and then one or two between the head-depending on what type of system you are auditing-I began to think that this might be a backward approach to efficiency.

Does it really allow me to make a good irrigation system out of a bad one without almost rebuilding the system? I know that I can correct incorrect nozzles that don't provide match precipitation rate (MPR), some pressure issues, tilted sprinklers, sunken sprinklers, broken sprinklers, stuck valves that weep water continuously creating boggy areas and a few smaller items.

How do I correct a water supply source that was sized incorrectly-too small in quantity and pipe diameter? It's a big issue now as the piping in a golf system is everywhere and dependent on the source to provide the gallons per minute (GPM) and the pounds per square inch (PSI) required to throw the water as evenly as possible-known as the distribution profile of the sprinkler-which when designed correctly can result in shorter run times because the water is applied almost as evenly as Mother Nature does with a good heavy rain (without wind).

What would happen if the precision and care that we teach in our auditing classes to potential new auditors was conveyed during the research, planning and design, selection of quality contractors, installation and final commissioning of irrigation systems? Would we then find all the problems-wrong sprinkler type, wrong nozzle, poor pressure, incorrect spacing, mixed precipitation rates, sunken, tilted, broken heads-that detract from the ability of the system to efficiently provide water for the plants? Good question, isn't it, and one that should start you questioning what we-irrigators-as a profession, are doing. So far we have had to wait until the EPA and other government entities tell us what we are going to do if we want to irrigate using their water. Makes me proud?

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We, the irrigation industry are better than this. We have excellent training that did not exist 10 years ago. In fact, you can receive a university degree in irrigation by attending the four-year program offered at CalPoly Pomona, Calif. During a recent golf auditor training session that I was conducting, it became apparent that the approach to design and our methodology is combined with intimate knowledge of what we are designing. When it all comes together, we will be successful at creating a uniform and efficient watering machine-one worthy of being called a high-efficiency system. If not, we have created another water waster-known as a Get It Wet system-that can now join the ranks with the many others out there.

To be able to get inside to where a design needs to begin, you need to get intimate with the project, the golf designer's thoughts, the owner's wishes, the golf superintendent's requirements and the eventual golf technician's concerns for ongoing maintenance. You need to know all about the water and power supplies, the many varied soil types throughout the course, especially the USGA makeup of greens and their specific watering regime requirements. Forward-thinking designers are incorporating spray heads along the bunker edges to water the fringe areas without the use of the large rotor water droplets that pound the bunker sand, causing channels to be formed and even eroding the steep sides. Members will not be pleased if they end up in the trap, and especially when they find play is now disrupted due to the water channels that have been carved out of the sand.

Another approach I have heard about is the use of landscape dripline utilizing the lower flow per hour rating (GPH), installed 12 inches apart cut so it forms a six-inch triangular spacing, buried at a four-inch depth. Of course, this precludes aeration in these areas, but they usually don't extend more than a few feet in width out from the bunker's edge. Other issues that come to light is that, in some of the warmer locations, the superintendent requires that the sand be of a certain moisture content so that a golf ball caught in the trap stops almost where it lands rather than rolling or bouncing to a less desirable location-like under the rim.

Saving water by being intimate and focused on the desired outcome will enable the designer to achieve a water-efficient system, but it depends on good information.

"Golf course irrigation audits produce detailed information about actual irrigation system performance on the course (as opposed to theoretical performance). These procedures can be used to evaluate both new and existing golf course irrigation systems." 1

A well-designed and engineered sprinkler will cover its intended target area as evenly as possible. Notice how the shorter range nozzle set (in the photo) has been designed to fill in the weaker section of the long range nozzle closer to the rotor. If a person designing irrigation systems does not know this fundamental information about sprinklers and how they should be laid out, what kind of system will the owner, superintendent, and golf technicians end up with? Not a water-wise one, that's for certain. So if you are the proud owner of this puppy, what can you do to make sure the playing surfaces are green and you are not asked by your members, "Where's the Green?" You got it! Crank up the water by cranking up the station run time which wastes lots of water.

Here's an example to clarify this: given plant water requirement (PWR) of 27 inches per year, with a uniformity of 60 per cent, the water that you now need to apply to satisfy the PWR, called the irrigation water requirement (IWR) has now increased to 35.63 inches. It takes 27,154 U.S. gallons of water to cover an acre (43,560 square feet) to a one-inch depth-known as an acre inch. Take a course that covers 100 acres x 35.64 inches x 27,154 gallons equals 96,776,856 gallons of water per year required to provide the plants that make up this course with enough water. 2

Spend a little more time in the planning and design phase, ensure the system is installed as per design by qualified, experienced golf irrigation contractors and you should be able to increase the distribution uniformity of the system. If you can just squeak out a 10 per cent increase in DUlq-DUlq is the water caught during a catch can test where the lowest quarter water catchments are compared to the average of all catchments-the water consumption will drop, using the above example, to 89,173,736 gallons for the year. It is a savings of 7,603,120 gallons that did not need to be pumped or paid for in some cases. Pump savings are calculated by finding out the gallons per minute (GPM) that the pump would operate at. For our example, let's use 1,000 gpm divided by the 7,603,120 gallons savings equals 7,603.12 min./60 equals 126.7 fewer pump hours/eight hours pumping per irrigation cycle equals 15.8 days (savings). Add on the cost of water, power, and staff and you will see that a 10 per cent increase in efficiency is well worth while going after. 

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 Testing pressure at golf green rotor.

Ok, enough of the math. How can I achieve a 10 per cent increase in DUlq on an existing course? Simple-plumb the rotors. Is it worth it? The savings will be in the thousands, in fact around $6,000 to $10,000.00, depending on what you do or don't pay for. These savings continue every year while the cost to do the work is done once, if done right, which it will be, right? Now, if you are developing a new course, you don't have rotors to test and fix, do you? No. So then how do you achieve an increase in efficiency when you have nothing more than an AutoCAD design to go from? First, I pray the design was created by a skilled golf irrigation designer-preferably a certified irrigation designer. What would you say if I said there is computer software available that you can do what-ifs which allow you to change sprinkler head layouts and see how the DU, SC (scheduling coefficient) & CU (coefficient of uniformity) numbers go up in efficiency (closer to 100 per cent, even though I am told if we hit 70 per cent for rotors we are doing good. Not for me-I demand more). Now you can almost determine the level of efficiency your system will deliver, given that all goes right. Now you can answer the question, "Where's the Green?" Good luck.

Lorne Haveruk, CID, CWCM-L, CGIA, CLIA, CIC, is principal of DH Water Management-a water resource consultation firm. It provides planning, consulting, design and project management of city supplied, reclaimed and reused water for all efficient irrigation systems. Contact the author directly at lorne1@dhwatermgmt.com  or visit www.dhwatermgmt.com.

References

1 Golf Irrigation Auditor, The Irrigation Association, www.irrigation.org.

2 Golf Irrigation Auditor, The Irrigation Association, www.irrigation.org.