Inside “The World’s Largest Smart Water Implementation,” Launched in 2010

July 1, 2011

A far-flung grid of 430 automated, Internet-enabled, weather-tuned irrigation controllers will eventually take charge of watering 700-plus acres’ worth of parks, medians, and streetscapes for the City of Santa Clarita (population 275,000), located in water-challenged Los Angeles County, CA. As a deployment of water management automation, it is being touted as the biggest such project anywhere so far.

Phase one—the installation of 103 HydroPoint Data Systems Inc. WeatherTrak pro 2C model controllers—began in late February and was due by May. Being taken out of service to make room are “about 30 to 40 weather-based controllers already in the field” that were working okay, alongside wasteful timers that are “older, outdated, and inefficient,” says Jason LaRiva, a specialist for the city’s landscape management districts.

And the savings? About 20–40 million gallons per year. Future phases should push that beyond 180 million gallons yearly, which works out to 25–40% of current volumes.

Such numbers will result, primarily, says LaRiva, from fixing past inefficiencies imposed by inflexible timer technologies. These suffer from being basically limited to two crudely seasonal modes a year—“summer program” and “winter program.” As such, timers “don’t take account of daily changes in weather.”

That is a huge efficiency killer. Example: During an unseasonably cool June 2009, sprinklers chugged merrily along, spraying rainbowed arcs for 20 minutes per cycle, “when they probably could have gone with 10 to 15,” he says. The new equipment, though being equipped with a “real-time weather adjustment” capability, will enable the city “to chip away at reductions on a daily basis.” Adjustments can be made based on weather fronts, ET rates, temperature, humidity, even wind. Automated weather sensitivity shuts off irrigation in advance of oncoming rain. Or, if a shower should arrive unannounced, grounds sensors do the shutoffs. LaRiva observes, rather dryly: “It would be not in our best interest to be seen watering while it’s raining.”

Historically, doing a shutdown during rain occurred manually, requiring legwork and dispatching.

To calculate, in advance of purchase, how much water might actually be saved, during summer 2009, LaRiva’s department pre-tested the proposed system at an 11-acre park.

He explains the setup process that CBET systems use: First, you must dial-in assorted data on soil attributes, plant types, and flow rates; this enables water schedules “to target root zones, minimizing runoff…. If your plant has a typical two-inch root zone and your soil is a sandy loam, and you live in a hot area, it’s going to make those adjustments to water an adequate amount,” he says.

“The most important part of a weather-based controller is to establish a base run time,” continues LaRiva. “Typically, you want to use that as your maximum”—i.e., the level of irrigation needed during hot dry spells.

Next, the ET-driven controllers were fine-tuned for a month. Water application rates were dialed-in to balance water efficiency priorities against the need to maintain healthy plants and park usability.

At the end of the test, past water usage was compared. Results showed that the system sprinkled forth “the least amount of water we’ve used in that park in the last 11 years”—yet without harm to greenery. Comparing 2009 to 2008, water consumption declined an impressive 25%—844,000 gallons.

More negatively, though, installed costs for phase one equipment are steep, at about $4,000 per controller, times 103 units. Payback on the investment—assuming higher water rates ahead—will take up to six years. “We’ve had some questions and sticker shock, like, ‘Wow that’s an expensive controller,’” he concedes. But the pricing also includes extensive preparatory labor for removal of old concrete pads; rewiring; adding new conduit; electrical upgrades; ground fault interrupting circuits; enclosures; controller installation; wire marking; station identification; and attribute setup. And looking forward, the City will receive monthly performance reports and a lengthy subscription to weather data and wireless communication—all part of the deal. “There’s a lot behind that $4,000,” he says.

He sums up: “First and foremost, our goal in doing this was to reduce the amount of water we were using. That also helps local water purveyors meet their 20% reduction by 2020 mandate [a state requirement]. That helps us to start setting an example in the surrounding community for our homeowners, that we’re able to reduce by this much and send that message out there, and it shows how important it is that we all do our part. That was the motivating factor.”