Maintenance Control System Water Use Irrigation Pump & Hydraulic Distribution System Distribution of Uniformity Recommendations

Irrigation

Maintenance

Age

Different sections of the course have been redeveloped since the current irrigation system was first installed. The older sections, such as the 5th and 6th fairways, are over 40 years old and are generally using single row large capacity valve in head sprinklers which are performing well below modern requirements. A number of holes: the 1st, 8th,9th,10th,11th12th and 13th, were upgraded around the early 2000s. The driving range is the newest part of the course, installed at the beginning of 2019.

Pipe systems that use PVC pipes of 80mm and larger often develop failures at junctions such as tee branches and changes of direction. As the age of PVC pipes increases, they become more brittle and are at a greater risk of breaking. Some of the newer mainline, mostly immediately downstream from the pump shed are 250mm and 200mm poly PE100 pipe. This material is a far better pipe material to use due to its flexibility, durability and the fact that fittings can be of a welded type that all but eliminates failure.

The control system hardware is made up of two different control methods. The older parts are a hydraulic control system that uses a pressure-based signal transmitted through a ¼ inch tube, pressurised by an additional pump system that run from the satellite boxes to the irrigation valves. This type of system is no longer used on golf courses or other landscape-based irrigation system due to its high level of maintenance and poor reliability.

There are two satellite boxes that have been converted to electric adjacent to the 3rd green. These send a 24-volt signal through wires to the solenoid valves. The newly-upgraded driving range has the latest technology which uses a two-wire cable that sends power to operate solenoid valves, as well as a communication signal sent to a device attached to the solenoid valve. This system does not require satellite boxes in the field or 240-volt power cables to operate satellites.

Photo: 18th approach irrigation blowout

Efficiency

The efficiency of the irrigation system is comprised of two main areas, application or distribution uniformity (DU) percentage and the areas being covered by the sprinkler system. There are two outcomes when areas do not receive the correct amount of irrigation: they either dry out, which leads to poor turf quality, or they need to be manually irrigated by hose and sprinkler. Manually irrigating can result in over watering. It is time consuming and takes staff away from other duties. Some manual water of greens is required on most golf courses to achieve the balance between water needs of the grass and the firmness of the playing surface.

Other areas may receive too much water, resulting in excessive growth of turf, usually in roughs, which leads to additional mowing of these areas. It also results in extra weeds, which requires chemical and resource inputs to maintain.

The 5th and 6th fairways have single row sprinklers in the middle of the fairways which provide poor DU% and as a result, significant time is spent on manual watering.

Many areas of the course are overwatered because of sprinkler placement, and sometimes the model of sprinkler. This results in significant areas of rough being irrigated when not required. Areas where this has been addressed over recent years include the driving range, half the 2nd and 4th holes, 8th hole and 13th hole. This is an area where savings can be made with an irrigation re-design.

A modern irrigation system is needed to minimise manual irrigation. It should also be flexible enough to allow for changes in future needs without major works being required.

Photo: 5th irrigation repair across bunkers

Irrigation Maintenance Costs

The table below shows irrigation maintenance costs over the last five years. The years 2017 and 2018 show a steady increase in the dollars spent on irrigation. While the 2019 year shows a reduction in dollars the time spent on irrigation increased. This could be attributed to more work being performed by staff instead of outside contractors.

Given our experience, and no maintenance issues with the new irrigation system on the practice fairway, there would be an approximate saving of 75% on materials and labour costs and 30% on power costs. This would mean an expected saving of approximately $440,000 over five years, or $88,000 per year.

 

Materials & contractor costs over five years

Year Hrs spent on maintenance Materials & contractors
2016 1,499.08 $34,652.00
2017 1,177.08 $46,383.00
2018 545.25 $54,041.00
2019 839.42 $43,154.00
2020 1,303.50 $51,806.00

 

Materials & contractor costs over five years

Materials, contractor, labour & power costs over five years

Year Materials & Contractors Labour Costs Power Costs Total Cost
2016 $34,652 $59,963 $62,922 $157,537
2017 $46,383 $47,083 $69,155 $162,621
2018 $54,041 $21,810 $74,774 $150,625
2019 $43,154 $33,576 $85,444 $162,174
2020 $51,806 $52,140 $70,018 $173,964
TOTAL $230,036 $214,572 $362,313 $806,921

 

Irrigation costs 2016 – 2021

Control System

Generally, a golf course central control system can be divided into two parts: field hardware and software and office hardware.

The software being used for all areas, except the practice fairway, is the Toro LYNX system which was the industry leader for many years. Its shortcoming at present, compared to the main alternative, is the lack of two-way communication with what is happening in the field. The signal is sent to the satellite in the field, however, there is no way of knowing if it is operating the valve/s required and no other information such as rainfall, temperature, soil moisture and flow rates can be sent back to the control computer.

As previously mentioned, the majority of the field hardware is old technology and requires a hydraulic system to open and close valves. This also results in the need for a small pump system with redundancy, for the supply of the water used in the control system. At present this is the weakest part of the irrigation system and replacement should be a high priority. The practice fairway, which was upgraded in January 2019, runs the latest control system. Since the installation of the system, there have been no issues with breakages, blowouts, or repairs. The only maintenance needed is the trimming of the sprinkler heads. This system has been well received by the industry and has now been installed into enough top golf courses around Australia to provide a reasonable assessment of its features and reliability.

Photo: New irrigation design and layout 

Water Use

Current expected water use has been based on the area of different sections of the golf course. This was taken from an AutoCAD file, with changes in the areas being managed as reflected on aerial images. Assumptions have been made to some sections such as roughs, fairway edges, and green approaches and surrounds.

Irrigation quantities are based on the expected water requirements of a high-quality golf course with a medium to high traffic rate.

The calculated water use is slightly higher than actual usage. This would indicate that the golf course irrigation is being well managed.

Expected water use based on industry standards

Location

Area in hectares

ML/hectare allowance

Irrigation Water Use in ML

Greens, surrounds & approaches

2.79

10

27.9

Tees and miscellaneous areas

1.46

8

11.7

Fairways and 6m of roughs

18.9

7

151.8

Total Water Use

 

 

191.4

Irrigation Pump & Hydraulic Distribution System

Irrigation Pump Station

Four Grundfos CRIE64-3-2 22kW operating at 6.5bar provides 94L/sec or 5640 L/min. In practice this flow rate would unlikely be achieved because of the limiting factors of pipe sizing and the distance water is moved around the course. The pump station control system is matched to the pumps and there are no known issues with the system.

Photo: 7th irrigation pipeline repairs

Mainline Hydraulics

Irrigation central control system (Toro LYNX) is set to a maximum capacity of 80 L/sec or 4800 L/min.

Calculations from pipe sizing and routes were based on a Hydroplan drawing, however, there are some areas where information is missing or questionable. This is due to the age of the system and lack of knowledge in these areas. They are mainly in the 5th and 7th green and 6th tee area, between the 12th fairway and 13th green and the 4th green and 5th tee and 5th fairway.

Generally, the first 445m of main heading south into the front nine holes and 549m of main heading north into the back nine holes are too small for the flows that are being used by LYNX. These pipes range in size from 250mm down to 150mm PVC and should not be subjected to a maximum flow from the pumps of greater than 50L/second to avoid high water velocity in the pipes. Water velocity in pipes should be kept below 1.5m/second. Flows above this rate have two negative impacts.

High flows rates mean high velocity through pipes (above1.5m/sec). This increases friction losses, this in turn requires the pumps to use more power to achieve the pressures and flows in the field resulting in higher than desired electricity use.

Secondly high velocities cause faster wear in pipes at tee sections and bends. This is more prevalent in PVC pipe. It also increases the likelihood of pipe breakages, once again far more likely with PVC pipe.

Once mainline pipe sizing drops to 100mm PVC there is significant reduction on the flows achievable while maintaining the required pressures and keeping flow rates below the recommended 1.5m/sec.

As an indication these areas include the majority of the sub mains that run along most fairways. These are generally 50mm to 80mm pipes and limit the number of sprinklers that can be efficiently operated at any one time in a number of areas. These include the 2nd, 3rd, 4th and 5th holes on the front nine, and the 8th, 9th, 12th, 13th, 15th, 17th and 18th holes on the back nine.

Recommended maximum flow rates for various pipe sizes

Pipe Section

Pipe Material

Diameter mm

Attributed Flow L/sec

Pressure Loss in kPa/100m

Velocity m/sec

Mainline 1

PE100

250

50

7

1.4

Mainline 2

PE100

200

32

9

1.4

Sub main

PVC cl 9

150

24

11

1.4

Sub main

PVC cl 9

100

12

16

1.4

Sub main

PVC cl 9

80

7.5

23

1.35

Sub main

PVC cl 9

50

3.4

36

1.5

Distribution of Uniformity

Summary

Catch can tests were conducted on 2nd and 3rd September 2019 to determine the distribution uniformity (DU) percent which is a guide on the effectiveness and efficiency of the tested areas. Industry benchmark is 75% with anything below 60% needing more urgent attention. Precipitation (PR) rates are also recorded. The area being tested can be compromised by variations in the width and length of the area and this needs to be taken into account when assessing the overall performance of the system. Thirty six catch cans were used for all areas, with stations being run for 15 minutes to give an accurate result.

DU% Results

Fifth Fairway

Station Numbers

7 and 8

Number of Heads – total

2

Distribution of Uniformity %

29%

Average Precipitation Rate

16.3 mm/hr

Sprinkler type and model

Toro 690

Nozzle Pressures in kPa

300 – 320

 

Practice Fairway

Station Numbers

18,19,20 and 21

Number of Heads – total

4

Distribution of Uniformity %

78%

Average Precipitation Rate

18.4 mm/hr

Sprinkler type and model

Rain Bird 750 and 751

Nozzle Pressures in kPa

400-480

 

Sixteenth Fairway

Station Numbers

8,9,10 and 11

Number of Heads – total

4

Distribution of Uniformity %

76%

Average Precipitation Rate

40.2 mm/hr

Sprinkler type and model

Toro 835

Nozzle Pressures in kPa

380 – 500

 

Eighteenth

Station Numbers

17 and 18

Number of Heads – total

4

Distribution of Uniformity %

69%

Average Precipitation Rate

22.2 mm/hr

Sprinkler type and model

Toro 850

Nozzle Pressures in kPa

420 – 500

 

Fourth Tee

Station Numbers

3,4,5 and 6

Number of Heads – total

4

Distribution of Uniformity %

63%

Average Precipitation Rate

36 mm/hr

Sprinkler type and model

Toro 730/760

Nozzle Pressures in kPa

N/A

 

Eighth Fairway

Station Numbers

20,21,23 and 24

Number of Heads – total

4

Distribution of Uniformity %

69%

Average Precipitation Rate

18.8 mm/hr

Sprinkler type and model

Toro 835

Nozzle Pressures in kPa

360 – 400

 

Sixth Fairway

Station Numbers

27 and 28

Number of Heads – total

2

Distribution of Uniformity %

32%

Average Precipitation Rate

10.2 mm/hr

Sprinkler type and model

Toro 690

Nozzle Pressures in kPa

380 – 440

 

Recommendations

While the DU tests provide a relatively good result except for the 5th and 6th fairways, these results are only part of the analysis. Overall the existing irrigation system has weaknesses in the control system, the sizing of most pipes, the age of some of the pipes and other components.

While the below recommendations are generally made in isolation, the total amount of work suggests that a combined upgrade of the entire course be undertaken.

Change the control system

The irrigation control system is a weak point in the system. Replacing it with the system being used on the driving range would see improvements in control, reliability and remove the satellite boxes around the course. It would also remove much of the 240-volt power supply cables that provide a hazard to the staff and contractors when excavating for repair or rebuilding work. Valves and sprinklers would also need to be upgraded at this time to suit the new control system.

Photo: 19th hole irrigation repairs

Upgrade single row fairway irrigation to multiple row

The 5th and half of the 6th fairways need the existing single row sprinklers replaced with a multiple row design.

Upgrade of the pipe network

Upsizing the pipe network would result in several positive outcomes.

It reduces the amount of energy required by the pumps to move the water through the pipes by slowing the water velocity which results in a reduction in friction losses.

Secondly it will reduce the watering window allowing the Club to take advantage of savings in off peak power rates, may reduce evaporation by water later in the night when temperatures are generally lower and reduces the impact on early and late golf rounds.

Replacing the PVC mainlines and submains with poly PE100 pipe should eliminate any broken pipes over the next 50 years. The life expectancy for PE100 pipe is a minimum of 50 years with some studies showing it to be greater than 100 years.

Photo: Leaking satellite on the 1st

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