park boulevard median run off elimination

Water Wise IrrigationPark Boulevard Irrigation RetrofitApril 3 2013

Park Blvd median conditions prior to retrofit

Despite proper scheduling run-off is visible after short run cycles

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

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

“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

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

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.

Application Rate of Sprinklers

½ in/hr2 + in/hr vs

MP RotatorConventional Spray Nozzle

“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

Existing spray heads were marked

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

Pressure readings were taken with old nozzles

MP Rotators were installed

“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

Technical info on nozzles chosen for retrofit

MP Rotators tm 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.

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’

MP 1000

MP 2000

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

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

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

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

Park Blvd median conditions before retrofit

Even short cycles led to run-off and pooling

Park Blvd median conditions after retrofit

Longer run times scheduled and run-off is eliminated

Park Blvd median conditions before and after

AfterBefore