July-August 2007

Master-Planned

An awesome design, a state-of-the art central computer, and lots of synergy make the irrigation system at Ladera Ranch the unseen gem of this award-winning community.

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By Mark Saunders

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What has a quarter-million sprinkler heads, 8,600 valves, 250 online controllers, and two weather stations; irrigates 750 acres; and saves homeowners $815,000 and 350 million gallons of water per year? If you answered the irrigation system for the Ladera Ranch in unincorporated Orange County, CA, then you’re a winner. Actually, the real winners are the 8,100 or so homeowners in this 4,000-acre master-planned community in south Orange County.

As with any award-winning landscape project, Ladera Ranch’s eye-catching community parks, slopes, trails, and creeks require a great deal of care. In fact, it takes untold man-hours, a high-tech central computer, and almost constant communication between four different organizations to make this slice of southern California’s semi-arid desert bloom.

Ladera Ranch receives between 13 and 14 inches of rain per year, not enough precipitation to sustain this master-planed community that is quickly evolving into its own city. To compound the development’s water concern, all of south Orange County sits atop a shallow groundwater basin that is far from deep-well friendly. According to Santa Margarita Water District Chief Engineer Dan Ferons, south Orange County’s groundwater basin could be described as a slow-flowing underground stream. “It doesn’t really store the water,” says Ferons. “Most of it ends up draining into the ocean.”

This dearth of groundwater storage puts a premium on good sources of domestic water for homeowners and recycled water for landscaping; however, the nearest source of potable water, the Colorado River, is a four-hour drive, with the next closest source of domestic water coming from the San Francisco Bay Delta. In other words, intelligent irrigation design and sophisticated delivery systems were a must.

Ladera Ranch Design
Ladera Ranch’s parent company, Rancho Mission Viejo, contacted the irrigation consultants at Water Concern to design and manage the irrigation system for most of the 750 acres of Ladera Ranch’s common areas, which includes three large village parks, five school parks, 10 neighborhood parks, dozens of pocket parks, a 4-mile walking trail, and a 24-acre sports park. According to Steve Hohl, director of irrigation services at Water Concern, “It was thought out well before the design started: the utilities. For example, all the water and electrical lines, the communications, the radio systems were planned in advance of the construction drawings. Once those started, you just look at your master plan to refocus. We set limitations on flow and water usage on each meter before we started the design. So we knew that when we were starting on a rec center in the middle of town, we’d look at the master plan that indicated a landscape area of 1.25 acres, so we knew that we had 35 gallons per minute to irrigate the site, and we just stayed within those flow limitations.”

The Rain Master System
Water Concern decided the best course of action involved the creation of a comprehensive plan that would allow irrigation of 750 acres where and when needed—like the 9 p.m. to 6 a.m. window for recycled water mandated by the Santa Margarita Water District. After careful study, it was determined that 25 gallons per minute per acre was the ideal rate of flow given the topography, soil types, and plant materials. “We really wanted to make sure that by the end of the project build-out we could apply the irrigation demand within local health code standards and the limitations of the infrastructure,” says Hohl.

To achieve that end, two things were needed: a centralized computer system capable of simultaneously handling thousands of computations concerning flow, volume, and piping constraints for all the common areas and an expert/hands-on irrigation specialist to manage the central system. Say hello to Rain Master Evolution and Todd Coward.

The Rain Master Evolution system used at Ladera Ranch comes with two modules: Evolution Advanced ET (evapotranspiration) and AIM (Advanced Irrigation Management). According to Rain Master, the Advanced ET schedules irrigation based on plant needs, soil types, and evapotranspiration rates. The AIM controls the complex flow regulation requirements of the system.

“At the end of the day,” says Hohl, “it helped to balance the flows throughout Ladera by lowering total watering duration by combining valve start times and saved money by reducing infrastructure size. … That’s one of the things we designed for, and that’s where the Rain Master system comes in because it was able to manage it at the same time. And that’s explicitly why it was chosen over some of the other products. That’s what we needed. We designed it so we’re not overtaxing the system, but we wanted to make sure that when the controllers turn on the irrigation is doing exactly what we intended when we designed it.”

Water Concern brought Coward on as central control irrigation manager to run the central system at Ladera Ranch in 2004. Coward’s expertise and the system’s level of complexity were a necessary fit to maximize this labyrinth of pipes and keep the development’s open areas looking like a realtor’s brochure year-round.

“If you had a standalone system, it would almost be impossible [to irrigate the entire area successfully],” explains Coward. “You’d have an Excel spreadsheet 2 miles long trying to manage that. With the central system, we can say which area we are going to irrigate.”

Photo: Water Concern
Ladera Ranch’s eye-catching landscape requires extensive care.

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Coward elaborates on how the system allows for fine-tuning to meet specific irrigation needs, explaining, “During peak irrigation at night, we’re only going to have 75 gallons per minute go through a certain area. Then we can go to the next area and allot 20 here, and 50 here, and 25 there. The central calculates the run time for each night’s irrigation. I can manage the subtleties of each zone, so if we have a zone that is getting a little drier, I can go ahead and adjust a host of different factors. … If I see something like a tree was cut down and I have a turf zone that was dry because it was in the shade most of the time and now it’s in the sun, I can increase a factor for that zone and it will increase the amount of water that zone receives. It’s not a program-it-and-forget-it system. I don’t think any central is. You’re constantly managing the system, increasing it a little bit or decreasing it a little.”

A highly adjustable central system allows Water Concern to remain flexible with regard to water use and how to work with Santa Margarita Water District with regard to routine maintenance as well as unplanned service interruptions. According to Ferons, a centralized system makes it very easy to coordinate planned maintenance so Water Concern can shut down the portions of the system and eliminate demand. Next Page >

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