After 9/11, water utilities began taking a serious look at protecting their water distribution systems from a terrorist attack and also from a number of contaminants that could be introduced into the water accidentally.
Water utilities use sensors to measure chorine, pH (acidity), turbidity, temperature and total carbons in water supplies, but nothing was available to detect something like anthrax or arsenic.
That was the challenge the U.S. Environmental Protection Agency (EPA) was faced with in searching for a solution. “The challenge was to try to use existing sensor technology to try to detect these types of contaminants,” said Regan Murray, a research scientist at the EPA. The EPA developed software it calls Canary, which along with the sensors, has so far yielded results in places like Cincinnati and Singapore.
When a contaminant is introduced into the water, the sensor values change and the Canary software detects whether that change is significant. If it is, someone is notified and tests the water. So far the software appears to be successful, but luckily hasn’t had to confront a terrorist attempt yet.
In the Lab
Scientists at the EPA began experimenting in the lab with sensors and a multitude of contaminants to determine if the same type of setup would detect impurities other than what they already check for. They designed a loop that simulated a real water system where water flowed pipes. They introduced tap water and contaminants, and then measured how the sensors changed in the presence of the introduced chemicals.
“We did 23 different contaminants, which included things like pesticides and some biological organisms like E. coli and also some other things we’d be more worried about terrorists using in the water,” Murray said.
They found that the sensors indeed signaled that the water quality parameters had changed — that something was different in the water — which suggested that the sensors would work for almost all of the contaminants tested. Then they needed a way to automate the process
That’s where Canary came in. “We needed it to be a data-analysis process that would go on in the background so a person doesn’t have to look at the data to see if something unusual is going on but instead the software could do that,” Murray said.
There’s been a lot of software development that analyzes data and looks for patterns in the data so the EPA wasn’t starting from scratch. It used data mining, data fusion and other approaches to analyze the data for nearly four years before pinpointing a couple of software algorithms that did the job well. Those are used in the Canary software.
Does it Work?
The Greater Cincinnati Water Works serves about 1.2 million people, some retail, some wholesale customers. It was selected in 2005 to pilot the initial roll out of Canary. The pilot ended, and the water utility now maintains the system.
The utility has several components that monitor water quality, security, public health and customer satisfaction. Canary is one component of the program that monitors water quality throughout the distribution system.
Sensors are placed at various intervals throughout the distribution system. These monitoring stations take a reading of the water quality and send data back through the supervisory control and data acquisition system.
“Every two minutes the water-quality monitor data is pushed over eventually getting to Canary,” said David Hartman, assistant superintendent of the Water Quality and Treatment Division for Greater Cincinnati Water Works. “Canary is looking at that data and looks at past data and projects [to determine] what the anticipated reading or result would be from the station. Then, based on those results, when they reach a certain threshold that will set off an alarm.”
The alarm is both visual, on a computer screen, and audible to the operators that monitor the system 24 hours a day.
So does it work?
“There’s good news and bad news,” Hartman said. The system produces alarms, which is good news and so far there hasn’t been a situation that couldn’t be explained as something other than foul play. That leaves the unknown. If there is an attempted contamination of the system, will Canary work as it has been?
“Because we get alarms, the indication is that it works,” Hartman said. “The EPA has done a lot of work and is still doing work,” to ensure that it works.
Canary is free to anyone who wants to use it. The real cost is the hardware to run Canary and the water system sensors.