Join us for the first installment of our 2-part series on irrigation design for sports fields, presented by Donald D. Franklin of Franklin Irrigation Consulting, FIC. Donald will offer some key insights into designing for optimum efficiency, informed by his 51 years in the landscape industry and 4 decades in water management. He'll provide some best practices on selecting heads for your design and spacing them correctly. You'll also learn the roles played by water velocity in a sports field irrigation system, as well as the effects of head placement and other elements, such as wind, on the design as a whole.
Note: The following catalog of content covered in this webinar is time stamped to allow you to follow along or skip to sections of the video that are relevant to your questions. You can also search for content on this page using the FIND command in your browser (CTRL + F in Windows, Command + F in Mac OS.)
- Head Selection: The Right Product for the Application
- Head Spacing: Achieving the Best Distribution Uniformity
- Effect of Wind and Head Spacing
- Head Placement: High-Trafficked Areas
0:00 – 5:16: Intro/TOC#
About the Presenter (2:10)
Additional information: Resources from the Irrigation Association (irrigation.org) (3:35):
- Irrigation, 6th Edition
- Principles of Irrigation, 3rd Edition
- Designing, Operating, and Maintaining Piping Systems Using PVC Fittings by Ron D. Bliesner
- Hunter publications:
- Landscape Irrigation Design Guides from Rain Bird
5:17 – 14:59: Head Selection: The Right Product for the Application
Inlet size (5:17)
An inlet size of at least 1 inch is typically required for sports fields in order to achieve the proper distance.
Pop-up height: 4 or 6 inches (dependent on turf height) (6:45)
Dual nozzle (opposing nozzle) or single nozzle (7:58)
Stainless-steel riser or plastic (8:53)
Turf cup option (9:35)
Standard gear drive (used in most applications) (10:22)
Planetary gear drive (11:00)
- New technology
- Excellent in harsh conditions
- Softball infield
- Poor water quality (raw water from lakes, ponds, or ditch)
Correct pressure for the desired radius (12:30)
Spacing heads evenly (13:33)
How far should heads be spaced? (13:48)
- Wind dependent, speed and direction.
- In areas of high traffic, try to keep them out of areas where excessive wear occurs.
Correct nozzle for a specific distance (14:14)
15:00 – 34:43: Head Spacing: Achieving the Best Distribution Uniformity
What causes "donuts" in sports fields? (15:00)
- Low pressure
- Maintenance changing nozzles
- Higher demand due to construction
- Water agencies drop pressure
- Poor spacing
- Incorrect screw adjustment
Head spacing: Which is best: square, rectangular, or triangular? (18:45)
Use the pattern that best fits the area. You might even use more than one of these patterns in a single hydrozone.
Best coverage & highest distribution uniformity (21:20)
Never space heads at the radii published in manufacturers' catalogs because the distances are always based on zero wind conditions.
Typically, the best pressure for a specific nozzle should be in the middle of the pressure range.
- If a #15 nozzle is selected, the best pressure would be 60 – 70 PSI.
- Low pressure will cause poor distribution uniformity (DU), which results in longer runtimes, more water, and higher energy costs when booster pumps are in the system.
As a general rule, to achieve a high DU, the spacing should be between 95% and 80% of the radius.
- 57 x .85 = 48.45 or 48 feet.
Based on Space Pro, a program developed in the 1980s/'90s by Center for Irrigation Technology (CIT) in Fresno, CA, a designer can determine the best spacing depending on pressure, nozzle size, distance, and pattern.
Uniformity vs. DU at manufacturer's catalog spacing (Land F/X Uniformity tool) (28:49)
DU vs. uniformity at 85% spacing (30:14)
Example: typical football field with heads spaced at approximately 90% of manufacturer's published distance (31:18)
34:44 – 45:29: Effect of Wind and Head Spacing
To ensure head-to-head coverage, wind speed and direction must be accounted for. Head spacing may require as close as 90% to 50% of manufacturer's published radii.
Wind data (35:48)
Wind data can be viewed by:
- S. territory
- Zip code
National Oceanic and Atmospheric Administration (NOAA) map tool for local climatological data
Adjusting for wind (37:07):
- Look for prevailing wind conditions from local weather data.
- Run irrigation during non-windy periods.
- Sufficient pressure based on nozzle size (GPM) and spacing.
- Larger nozzles will allow the water to push through wind.
- Must have sufficient pressure.
- In general, shorten spacing for areas with a specific wind direction and regular heavier winds.
Head placement and circuiting (41:06)
Group heads together that have similar characteristics – for example, separate valves for:
- Full circle (360 degrees)
- Part circle (180 degrees)
- Part circle (90 degrees)
45:30 – end: Head Placement: High-Trafficked Areas
Keep heads out of high areas of play:
- Center field
- Goal areas
Group or circuit heads together where repairs are common:
- Goal areas
- Center field
Tying it all together (47:12)
- Select the proper head for the application:
- Pop-up height: 4" or 6"
- Stainless-steel or plastic riser
- Single nozzle or dual nozzle
- Nozzle size based on radius and pressure
- Pattern: triangular or shape
- Use a pattern that best fits the area.
- Head spacing
- As a general rule, to achieve a high DU, the spacing should be between 95% and 80% of the radius.
- Use the Land F/X Uniformity tool.
- Wind considerations
- Check project wind speed and direction.
- May need to space heads at 70% to 50% of manufacturer's data.
- Valve full-circle heads separate from part-circle heads.
- Group heads together where repairs occur frequently due to heavy play.
- Head placement
- Keep heads out of high-trafficked areas for player safety.
Question: Do you have trouble finding 6-inch rotor heads? (48:00)
Answer: Not necessarily. The heights used in this presentation are generic terms. Check the manufacturer's catalog.
Thoughts on whether or not to put all quarter heads on a zone (52:50)
Try to design the system as if you are going to need to manage it yourself.
Back-to-back fields and recovery (55:08)
Do not tie zones together between different fields.
Safety zones and sidelines (57:03)
Irrigate these areas separately.
Question: If you have a 15 full head, do you zone it with a 25 full head, or does it need to have its own valve? (58:10)
Answer: It will depend on the precipitation rates. If they have the same precip rate, they can be on the same valve. If they have different precip rates, each should have its own valve.
Preview of Part 2 of this webinar series (59:50)