Problems at treatment plant lead to water violation

A routine test of the town’s drinking water supply during the month of June turned up unacceptable levels of coliform bacteria — a relatively minor violation caused by “startup issues” at the Neponset Street water treatment facility, according to Dennis Morton of the Canton Water Department.

The department released a notice last week spelling out the details of the violation and explaining what it means for Canton residents. According to the notice, which can be found on the town website, the samples collected exceeded the maximum contaminant level allowed under state law, but it was not considered an emergency and did not require a boil water order.

“We took 91 samples for coliform bacteria during June,” the notice states. “Nine of those samples showed the presence of coliform bacteria. The standard is that no more than one sample per month may do so.”

The notice goes on to state that coliform bacteria are “naturally present in the environment” and are “generally not harmful themselves.” However, the bacteria are “used as an indicator that other, potentially harmful bacteria may be present,” such as fecal coliform or E. coli.

“We did not find any of these [harmful] bacteria in our subsequent testing,” the notice states. “If we had, we would have notified you immediately.”

Morton said the coliform-positive samples were not limited to one part of town and instead were found at sites ranging from the Canton Police Station to the Tolman water tank to Shaw’s Supermarket. The Water Department then “immediately” began resampling, and by June 27, the town was notified that all samples were free of coliforms.

Even before the negative tests came back, however, Morton said officials at the Water Department were “very confident” that the issue was related to “flow reversal” caused by periodic shutdowns at the new water treatment facility, which has experienced an assortment of minor problems, such as pump failures, since coming online in April.

“We’re experiencing some startup issues as we work to get the treatment plant running at an optimum level,” he said. “We also had a main break on Neponset Street — a 65-inch crack in a pipe — that contributed to the problem.”

Morton explained that the issues have resulted in “large changes in flow direction,” which in turn affects the scouring action within the pipes and can lead to a buildup of bacteria.

According to the public notice, local officials are currently working with the town engineers to correct these “flow issues” and have also been in contact with the Mass. Water Resources Authority and MassDEP. “We have been monitoring the system with regular bacteria sampling as well as monitoring chlorine residuals throughout town,” the notice states.

One recent issue that was not related to the drinking water violation was a chlorine leak at the Neponset Street facility on Tuesday, June 19. Morton said that was the result of a faulty valve on the tank. He was actually making a repair on the tank when he noticed the leak and then promptly notified local authorities. A regional hazmat team was brought in to contain and clean up the spill, which was limited to a small room within the facility.

Morton was also quick to point out the differences between last month’s violation and the one last fall that resulted in a six-day boil water order. The previous case, he said, involved the presence of E. coli and was caused by an animal carcass in a bird’s nest on top of a water storage tank on Indian Lane. Morton said the damaged vent that allowed the bird to nest on top of the tank has been repaired and should not pose a problem in the future.

Despite the fact that the recent positive tests were not deemed an emergency, the Water Department suggests that anyone with specific health concerns should consult his or her doctor. General guidelines on ways to lessen the risk of infection by microbes are available from EPA’s Safe Drinking Water Hotline at 1-800-426-4791. Residents can also contact Morton at 781-821-5017 for more information.

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Posted by Jay Turner on Jul 6 2012. Filed under News, Town Government. Both comments and pings are currently closed.