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).
The HS3, in addition to receiving data from the RFID seals and video from the cameras, also receives information from SCI's analytical software that constantly culls data from a variety of wired sensors that provide near-continuous water-quality measurements. If the RFID seals are broken, or if any of the data exceeds the system's pre-set, user-specified thresholds, alarms are triggered. These alarms, both visual and audible, are sent to the plant operators' monitoring station. Additionally, the alarms generate real-time images from the cameras, which also include several minutes of video generated prior to the alarm. When operators receive the alarms, they also receive the data and video. All of this information, Nelson explains, along with action recommendations programmed in by SCI, helps the operators determine the level of threat and the appropriate response to take, if any.
The EWS, with its surveillance cameras, RFID seals and various sensors, provides the plant with an automated monitoring solution. "Typically," Nelson says, "this water-treatment plant has two operators working around the clock. And as you might surmise, due to the fact that we are on the Rio Grande River, there are situations where there are people coming on to the property that aren't supposed to be there. This system helps the operators determine if someone is on the property that isn't supposed to be there. It also provides some sort of comfort beyond the operators walking the property."
Since installing the system in 2007, Nelson notes, there have been no serious incidents to date. But the system also helps the plant track the regularly scheduled monitoring required of the vault. "The RFID devices can help the operators determine, for example, if one of the clear wells was breached," he says. "With the added video that records what's happening when the RFID seal triggered the alarm, the operators can determine if the breach was a plant employee or someone unknown."
According to Nelson, the plant is now expanding its use of the EWS. Next year, he says, it will add another HS3 onto a chemical storage building used to house one-ton cylinders of chlorine. It's likely that RFID seals will be added to the cylinders, attached via the seal's cable that is also looped through the cylinder rack. If, at any time, the seal or cable is opened or broken, thus disrupting the electronic circuit that runs through the seal and cable, the RFID tag would transmit a signal initiating an alert. "We feel that there will be some [Environmental Protection Agency] EPA-authored legislation that will require additional security measures to protect these one-ton cylinders. So we are being proactive," Nelson says of the expansion.
