July-August 2007

Smart Solutions

In 2002, the Irrigation Association came up with testing protocols for the industry: The result was the Smart Water Applications Technologies.

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By Sue Marquette Poremba

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In Santa Barbara County, CA, nearly 50% of the water used goes into landscaping. Communities within the county developed the Santa Barbara County ET Controller Distribution and Installation Program, using WeatherTRAK ET Controller technology.  Homeowners with high water usage were targeted as participants. Average water use for January and February and again for July, August, and September for the previous three years was determined for each customer. These averages were used to create a ratio of the difference between summer and winter use, determining the highest irrigation times.

During the initial site visit, purveyor staff conducted an irrigation check by collecting information for WeatherTRAK Programming, evaluating the irrigation system, troubleshooting problems, measuring lawn areas, and running each station for determination of precipitation rates. If there were more than 12 active stations, staff would also determine which stations would be merged at this time.

After monitoring the first installations for a month or two, the partner purveyors and the customers initially found increases in some of the customers’ water bills. It was soon learned that in order to achieve the highest level of efficiency, it was necessary to determine the precipitation rates of the irrigation systems, i.e., to program the specific information into the controller rather than rely on the factory settings. Follow-up evaluations to review the controller were set up, and input precipitation rates for spray heads in turf areas and precipitation rate determinations were included as part of the initial site visit for all installations after July 2002.

Initial data indicate that customers are reducing their monthly water use by approximately 26%, with a high of 59% savings and a low of 8% savings.

In Boulder, CO, a three-year study was performed during a drought period, and the cities in the area had mandatory or voluntary watering restrictions. It was determined that an average of 35,000 gallons of water per site was saved with the SWAT technologies.

During this case study, three stations were set up on turf grass sites. Each station recorded air temperature, relative humidity, wind speed, and solar radiation. The data were used daily to calculate standardized reference ET using the 2000 standardized American Society of Civil Engineers Penman-Monteith equation for turf grass. Stations automatically transmitted data via modem and cell phone twice daily to district headquarters. An additional issue is that the Colorado Front Range Region, where the study was held, has numerous microclimates that can affect the ET from one city to another. To account for this, different zones needed to be established for each weather station.

An important finding of the study during 2002 was that the WeatherTRAK controller was able to adapt to local drought restrictions with more or less effort, depending on the type of restrictions favored by the local utility staff. Boulder’s goal was to achieve a 25% reduction in outdoor water use during the summer of 2002. However, the city didn’t believe that most of its customers could translate a goal of this kind to a watering schedule, so a system was used where watering was limited to 15 minutes twice a week for each zone, as a shortcut approach, and Boulder applied this to all customers.

The WeatherTRAK irrigation controller adapted to each of the drought measures and produced water savings. From the standpoint of water savings, for the group as a whole, savings averaged 30,000 gallons per year. When accounts that saved no water were excluded, savings of 64,000 gallons per year were observed. Monetary savings on those sites, which reduced their water use, ranged from $51 to $668 and averaged $190 per site. Since these savings were based on relatively low water rates, even greater savings could be expected as water rates increase.

In the Puget Sound area of Washington, a climate-based smart controller test was conducted among residents who had high water consumption, using hundreds of gallons of water per day more in the summer landscaping months than in the winter. With the controllers, consumers saved an average of 20,000 gallons of water per year.

Interestingly, the ET controller tested without a rain sensor produced water savings. The ET controller and sensor produced a lot more savings than the ET controller alone when the sensor alone seemed to have no impact on water savings. One possible reason is this particular controller has a 24-hour rain delay, which keeps the controller from coming back on for 24 hours after the sensor signals it to stop. Next Page >

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