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NEW YORK – Irrigation scheduling can soon be controlled from space. Promoters of a satellite-controlled irrigation system said a preliminary test of 40 homes in Irvine, Calif., showed that the sprinklers decrease landscape water use up to 25 percent and keep yards green, as well as reduce fertilizer, pesticide and fecal pollution from lawn-and-garden runoff.
Campbell Scientific weather stations collect data for the system that uses satellites to control lawn sprinklers. "To put the right amount of water on a landscape is time-consuming and sophisticated; and irrigation controllers are difficult to program and reprogram," said horticulturist Tom Ash of CTSI, a Tustin, Calif., water-conservation company. "It is very typical – people over-water. They set their controllers once [often for the hottest summer weeks] and they leave them."
The new system, made by Network Services Corp. of Petaluma, Calif., should be on the market in 2001, said founder and chairman Mike Marian, who invented the system. CTSI will help sell the satellite sprinkler controls in exchange for a cut of the proceeds.
Homeowners will pay $100 to $150 for a purple, roughly 8-by-8-by-2-inch WeatherTrak sprinkler-control box that receives signals from a paging-service satellite and replaces an automated sprinkler system’s existing control box. (Test models now cost $250.) There also will be a $4 monthly charge to have the satellite send commands to the control box.
In recent weeks, new tests began at 13 homes in the Salt Lake City suburb of West Jordan, Utah, and 10 homes in the Portland suburb of Wilsonville, Ore., said Ash.
He said satellite sprinkler controls also would be tested this fall on 50 Los Angeles homes, 250 more homes in Irvine and another 300 elsewhere in Orange County, Calif.. Fifty Reno, Nev., homes will try satellite-run sprinklers next spring.
HOW DOES THE SYSTEM WORK? The first step is a water audit of each home to be equipped with satellite sprinkler controls. Sprinkler leaks or other problems are fixed. Auditors determine how much water the sprinklers deliver to the yard.
Next, they program the sprinkler-control box so different sets of sprinklers deliver different proportions of water to various parts of the yard, based on vegetation type and whether each area is shady or sunny, has sandy or clay soil, is flat or sloped and so on.
A weather station in the same area measures soil and air temperatures, humidity, wind and solar radiation. A computer at Network Services collects the weather station data through modems, then uses it to calculate a seven-day evapo-transpiration (ET) rate, which indicates how much water is lost from the ground and used by plants. The ET rate basically says how much water is needed for a healthy lawn.
Network Services sends that information weekly to the satellite, which relays it to control boxes at individual homes. A receiver chip in each box picks the information relevant to local weather conditions, then reprograms sprinklers to irrigate each part of the yard appropriately.
Rain sensors override earlier commands if rain falls after the sprinklers are programmed for dry weather. The sprinklers can be programmed manually if they do not receive satellite commands.
Marian declined to identify the satellite and backup satellites his company hires to handle the sprinkler-control service. Not all satellites can perform the task, and Marian doesn’t want to help potential competitors identify those that can.
He said the satellite-commanded sprinkler system grew out of another company he runs: Solar Wind Systems, which makes sophisticated sprinkler timers, including those controlled by radio. Those systems are used by several cities in California and at the airport in Riyadh, Saudi Arabia, Marian said. But they are more expensive and require radio licenses, unlike the satellite-run system, he said.
West Jordan, a city of almost 70,000 people, decided to test satellite-controlled sprinklers as one of several efforts to conserve water.
"All the new housing developments are putting in grass, and a lot of people are over-watering," said Carl Hanover, city water-resources manager. "Demand is growing faster than supply. … Approximately 65 percent of the city’s water is used outdoors for watering. We are concentrating on reducing that percentage."
Hanover said that by minimizing over-watering, satellite-run sprinklers also reduce herbicides, pesticides, fertilizers and fecal matter that run from yards into storm drains and, ultimately, local waterways. If the experiment works, the city will consider installing satellite sprinkler controls for homeowners who volunteer, letting them repay the city via monthly utility bills.
In Irvine, the 40 homes tested already were conservative water users, yet satellite sprinkler controls reduced outdoor water use as much as 25 percent, Ash said.
He said homeowners agreed they saved water, their grass looked better and "they never had to touch their controllers again. They liked it."
One test participant was a doctor whose method of programming his old sprinkler control box was to "invite a friend, get out a six pack of beer, schedule the controller, then sit down and watch sports," Ash recalled.
With the satellite controlling his sprinklers, "now he says, ‘I can go straight to the beer and sports!’"