San Juan Island, Wash., is a popular resort destination where the population fluctuates with the season and the arrival of Orca whales and salmon. To get to the island, one must first drive an hour north of Seattle to the city of Anacortes. From there, take a two-hour ferry ride through a 130-island group to arrive at the 20-mile-long San Juan Island, which is at the waterway entrance to Puget Sound.
Managing a Critical Supply With Limited Resources
Bob Charters is president of the Cape San Juan Water District, which serves a small community on the south end of the scenic island. Their water comes from a freshwater lens floating on a saltwater aquifer.
Charters emphasized that, “monitoring the water usage is critical, as over-pumping could allow saltwater incursion into the freshwater lens and destroy the wells. We have three wells, two reservoirs and a water production facility on the remote southern tip of the island. Ensuring its good operation is, needless to say, very important.”
The utility had been sending people on a regular basis to check the facility, which entailed a two hour trip to a remote well house location. However, that put a substantial strain on the utility's limited part time personnel resources. “Watching that tank was wasting an hour or two a day,” Charters said. The utility obtained proposals for automating the monitoring job with radio and phone line based systems. “The prices were, well, you don't want to know what the quotes were,” Charters said.
Cellular Data Channels, Plus Managed SCADA
Mission SCADA systems use cellular data channels, instead of voice channels, to transmit data. Charters remembered asking, “Well, if this doesn't work like an autodialer with a regular cellular dialup, how does it call me and give me alarms? How do I see my tank level and well production data? I surely thought buying more equipment, like a SCADA computer and software, was going to be involved.” With Mission, however, one does not need a separate SCADA computer. Mission uses a large computer facility in Atlanta to present data and SCADA screens to the user over a secure Internet link to the customers' existing computers.
A Reliable Solution
TSI is a systems integration firm based in Seattle providing many engineering and service functions for the island's utility. TSI had recently been introduced to a new cellular-based monitoring product from Mission Communications. “These guys from Mission were telling us how much the system would do and how reliable it was even in bad cellular service areas. We figured it was just the same old new product promises,” Charters said. TSI, however, bid the integration of the Mission system into the entire job.
Charters, an experienced communications and computer engineer, accepted TSI's bid with only a few reservations. They were about the ability of the Mission unit to make a cellular connection in this remote part of western Washington, the Mission Control central computer facility, and the website development.
TSI made the trek to the remote site and installed a single Mission Model 110 RTU. The RTU was installed inside the well pump house and connected to monitor and report general alarms, pump failure alarms, pump run times for all three wells, one 4-20 mA tank level sensor, and a pulsing output from a flow meter. On a daily basis the system reports cellular service diagnostics, pump runtimes, cumulative flow, the daily high and low tank levels and the current tank level at midnight. High or low tank levels or other alarms are reported immediately.
“The system was really very easy to install,” said Jim Tahl, Field Installation Manager for TSI. “The only trouble I had was when I called with a question for Mission tech support. I had to climb one-quarter mile to the top of a hill before my cell phone would work properly.”
Connectivity Builds Confidence
Even though the cellular service is poor in the area, Mission recorded a 96% first transmission success rate, with 100% of the transmissions getting through within 40 seconds. Charters uses Mission's Web portal to check and analyze well pump performance, water usage and water tank levels.
“At first I would check the site almost every day, but as time went by, and my confidence in the system grew, I realized the system would reliably alert me to problems and my analysis of the sites performance only needed to be weekly. I found that even if I had web access problems, my alarm notifications worked smoothly. The system has worked very reliably,” Charters said.
“As you can imagine, reliability is of paramount importance given our location,” Charters concluded. “We can't just call up our service company and tell them to hop on over and fix a problem. After living with the Mission system since September 2000, the system works very well.”