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Laredo's Water Department Uses RFID to Maintain Law and Order

Thanks to active RFID tags embedded in seals, combined with motion detectors and video cameras, the Texas city can respond quickly to any threat to its water-treatment plant.
By Beth Bacheldor
Dec 04, 2008The Jefferson Street Water Treatment Plant, operated by the city of Laredo, Texas, is employing a system that combines sensors, RFID seals and motion-detection video cameras to monitor and protect the facility and water from contamination.

The so-called early warning system (EWS) was created by Canberra, a provider of measurement solutions for safety and security solutions, SCI, an automated process controls and instrumentation contracting company, and Hi-G-Tek, a manufacturer of active RFID tags and seals. The system was designed for use in a variety of applications that require real-time monitoring and documentation of events in order to protect such areas as water-treatment facilities, oil refineries and nuclear plants. The EWS, for instance, can generate real-time, automated warnings of contamination and send them to the appropriate personnel so authorities can act quickly to contain pollutants and minimize potential risks.

Laredo's Jefferson Street Water Treatment Plant, which supplies the city with its drinking water, is utilizing the EWS to protect the plant against accidental or intentional contamination. Because the facility is situated at the U.S. border with Mexico, and since the city uses the adjacent Rio Grande River as its source of drinking water, officials there must be on continuous watch, says Mark Nelson, SCI's instrumentation and controls department manager. SCI served as the systems integrator for the project, and also provided the analytical software and controller that gathers data from water-quality sensors. The plant, in particular, needs to be concerned with both unauthorized individuals that might come onto the multi-acre property (the area is prone to illegal border crossings), and pollutants that may have entered the water supply in Mexico, where source-water protection and discharge standards may not be equivalent to those in the United States.

To purify water, the plant employs a variety of techniques, including physical processes known as settling, chemical processes such as disinfection or coagulation, and biological processes such as lagooning, slow sand filtration or activated sludge. The EWS installation includes RFID seals from Hi-G-Tek, attached on the hatches of the plant's two clear wells—500,000-gallon tanks used to store purified water before it is sent off to the distribution facility. An RFID seal has also been affixed to the door of a vault that has a number of access ports into the facility's water pipes.

There are two Hi-G-Seals on each tank, each containing an active RFID tag that operates at 125 kHz, as well as at one of the lower ISM bands between 300 and 916 MHz. In low-frequency mode, the Hi-G-Seal communicates information over a short distance to a handheld data terminal; the higher-frequency mode provides two-way read-write data communication capabilities across a long distance. Developed by Hi-G-Tek, the tag uses a proprietary air-interface protocol designed to preserve the life of the battery. Most of the time, the seals remain in listening mode, requiring minimal battery power. According to Hi-G-Tek, the batteries have a shelf life of approximately five years.

Yakov Shadevich, senior manager of business development for Canberra, says the RFID-enabled seals make sense for the treatment plant because they can communicate wirelessly. "With RFID, you can take the seal and move it, in a matter of seconds, to another place," he states. "With wired seals, you have to move the wiring." The Hi-G-Tek seals are similar in shape to a padlock, for which there is a body and a loop on top. An electronic circuit runs, in a closed loop, through the seal. If that electronic loop is interrupted by opening, cutting or damaging the seal that secures the hatch, the electrical power flow changes, thereby triggering the RFID tag inside the body of the seal to begin sending signals. The signals, which include the tag's unique ID number, are picked up by an interrogator installed in a data-gathering and camera platform known as the Canberra Homeland Security Surveillance System (HS3).

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