The cost for the complete replacement of an 18-hole irrigation system today can easily exceed $1 million. At the high end of the scale, this cost can approach three times that amount, depending on variables such as:
- course layout and topography;
- extent and complexity of coverage;
- precision and sophistication of control system;
- maximum allowable daily irrigation (or syringe) periods;
- weather stations;
- soil moisture sensors;
- lightning detection and electrical disconnect systems; and
- auxiliary components (e.g., power cables for fans and sump pumps, fiber optic communication conduits, and piping and power for drinking water systems).
In addition to poor turf conditions and wet and dry spots, the effects of age and wear usually include decreased efficiency, which is always accompanied by increased waste of water and the power required to pump it. Some courses can afford the complete replacement package when the existing system wears out, but many can’t. What can you do, with limited financial resources, when the current system shows signs of age and deterioration?
The following can be done by irrigation contractors or by in-house maintenance personnel on a course-wide basis in one continuous project, or in phases to minimize the impact on your budget or cash flow.
Solving coverage deficiencies
If coverage deficiencies such as reduced distribution uniformity or an increase in wet and/or dry spots are the issues, check dynamic pressures at the heads with a gauge and pitot tube in the nozzles to verify that they are correct for the nozzles and spacings in the system. The pressure at all similar heads should be the same, regardless of elevation considerations or distance from the pump station.
You should also check and compare spacing to the radius of throw of the sprinkler heads. If the measurements are consistent but head-to-head coverage is not achieved, longer-range nozzles could be considered. However, longer-range nozzles usually use more gallons, so be careful that increased flow does not result in lower pressure at the heads. If spacing measurements are inconsistent, it may be necessary to relocate heads to improve uniformity.
Pressure regulation solutions
If pressures aren’t correct, the system should be analyzed by an irrigation consultant or other professional familiar with hydraulics in golf course systems. It’s possible that a simple adjustment at the pump station could solve the problem. In older systems, pressure regulation at the heads was often overlooked, and there are several options for adding pressure regulation.
If the remote-controlled valve in a block valve system doesn’t have a pressure-regulating feature, you can add one to some valve models or install a new valve with an integrated pressure-regulating feature. If the heads are to be replaced, you can install electric valve-in-head units, even in a block valve system. When the selector is set to the auto position, the pressure-regulating feature of the pilot valve is activated.
New heads are costly, but used ones are often available online or from local distributors. If head replacement proves too costly, another option is to replace the nozzles. All golf sprinkler head manufacturers sell replacement nozzles, and third-party high-performance nozzles are also available. Care must be taken to ensure that the replacement nozzles have the same GPM and radius values as the original heads.
Other common problems in older systems include gaps in coverage, block valve zones with too many heads, and broken 24-volt control wires. All of these issues can be corrected by adding zones.
If the controller is full and you need to add one or more zones, several devices are available that allow you to run two zones through a single control wire. Some of them allow different run times on each of the zones. You can also install small, battery-powered controllers in a valve box. When connected to a remote-controlled valve with a DC latching solenoid, these provide automatic control for the new zone without having to run one or more wires back to a controller. They can be programmed manually in the valve box or remotely with a hand-held device.
Improving monitoring systems
Performing an irrigation audit before and after any of these projects can document the improvement in efficiency and distribution uniformity. The Irrigation Association (IA) has a number of resources (audit guidelines, worksheets, publications, etc.) online at Irrigation.org that can help you evaluate your system. If you need to find somebody to audit your system, use IA’s online certified professional directory, to browse a list of certified golf course irrigation auditors.
Don’t let the lack of a large capital budget prevent you from making needed improvements to your irrigation system. Many changes can be made on a limited budget. They can result in improved distribution uniformity, reduction of wet and dry spots, better turf quality and more uniform playing conditions.
Jim Barrett, owner of the consulting and design firm James Barrett Associates Inc., is an Irrigation Association board member, certified irrigation designer and certified landscape irrigation auditor.