This document summarizes an irrigation retrofit project along Park Boulevard medians in San Diego. A team replaced existing spray nozzles with MP Rotator nozzles to reduce irrigation runoff. The new nozzles apply water at a slower half-inch per hour rate compared to the 2+ inches from the spray nozzles. This allows water to soak into the soil rather than run off. An audit after installation found lower application rates and more uniform coverage with the rotators. Runoff was eliminated, saving an estimated 20% of water usage. The retrofit improved landscape health with no pooling or runoff.

1. Water Wise Irrigation
Park Boulevard Irrigation Retrofit
April 3 2013

2. Park Blvd median conditions prior to retrofit
Despite proper scheduling run-off is visible after short run cycles

3. A team of City of San Diego staff was assembled
to tackle the challenge

4. Team Leaders
•
•
•
•
Mario Llanos – Park Horticulturist
Mike Tully – District Manager Citywide Park Maintenance Service
Bill Overstreet – Grounds Maintenance Supervisor
Greg Armstead – Grounds Maintenance Manager
•
City Of San Diego Irrigation / Maintenance Staff - Maria Castillo,
Noel Masing, Paul Lopez, David Gaspar, Richard Esquivel, Craig Moss and
Sheila Harshaw
•Chris Roesink – CLIA, CID

5. “Since our nozzle swap to MP Rotators in
the Park Blvd. medians, the turf and trees
in the median seem to be looking greener
and healthier than ever. More importantly,
we have significantly decreased run off
along Park Blvd.”
Park Horticulture Staff

6. What causes irrigation run-off?
• Application rate of water is too fast for the soil to intake
• Sprinkler “precipitation rate” another term for “application rate”
• High “precip rate” spray nozzles flooded medians until water ran off
• Established tree root mass prevented water from infiltrating soil
• Tight soils don’t allow water to soak in so it puddles in low spots or
runs-off into storm drains

7. Problem – Dry Season Run-off
Despite several previous attempts to adjust
conventional spray nozzles, periodically when the
sprinklers operated excess water ran down Park
Boulevard. This wasted water washed debris into
storm drains and out to San Diego Bay and ocean
contributing to water pollution.

8. Application Rate of Sprinklers
Conventional Spray Nozzle
2 + in/hr
vs
MP Rotator
½ in/hr

9. “The MP Rotator’s streams provide better
distribution to the turf allowing small
amounts of water over a longer period of
time.
This allows water to percolate through the
turf rather than putting down more water
through a conventional spray nozzle
causing overflow and runoff. ”
Park Horticulture Staff

10. Existing spray heads were marked

11. Irrigation catch can audit results showed high
application rate and coverage issues

12. Pressure readings were taken with old nozzles

13. MP Rotators were installed

14. “The retrofit was very simple and
convenient in that we could put the
new MP Rotator nozzles on our
existing pop-up bodies.”
Park Horticulture Staff

15. Technical info on nozzles chosen for retrofit
MP Rotators generically referred to as
“Multi Stream Rotating Nozzles” MSRN.
Rotators put out a gentle application of
water via multi-trajectory rotating streams
that cut through the wind and applied water
directly to the target at rates the soil can
absorb.
tm

16. MP Rotator Models used
•
Medians are spaced at approximately 13’ – 16’ wide
•
Narrows to a point at traffic lights and crossings
•
MP 200090 radius could be adjusted down 25% and worked
great for most applications
•
MP 100090 were ideal for smaller spacing and could be adjusted
down as low as 8’

17. MP 1000

18. MP 2000

19. A second audit conducted after the retrofit showed
a significant reduction in application rate and an
improved distribution uniformity

20. Pressure increased after conversion to
MP Rotators due to the significant reduction in flow

21. What changed?
•By switching to lower flow nozzles a stable operating pressure was
restored
•Run times were doubled from original settings with sprays to
accommodate for lower application rate MP Rotators
•Adjustable edges were fine tuned to prevent overspray on to street
and hardscape

22. Run-off was eliminated to storm drain
•All nozzles were eventually changed throughout the Park Blvd
medians
•Estimated 20% savings in water from traditional spray nozzles
•Improved coverage results in healthier lush landscape

23. Park Blvd median conditions before retrofit
Even short cycles led to run-off and pooling

24. Park Blvd median conditions after retrofit
Longer run times scheduled and run-off is eliminated

25. Park Blvd median conditions before and after
Before
After