For the second consecutive year the Hannibal Board of Public Works finds itself trying to figure out why a water test conducted late last summer at its treatment plant showed significantly higher-than-acceptable levels of a disinfection by-product.
Heath Hall, director of operations for the BPW, told the BPW Board at its December meeting that the by-product - trihalomethane (THM) - has nothing to do with last month’s complaints regarding the smell and taste of city water.
Hall stresses that this issue should not worry consumers.
“It’s not harmful. It’s not an immediate concern. The water is safe to drink,” he said.
According to information provided by the Missouri Department of Natural Resources (MDNR), a person would have to drink two liters of water every day for 70 years containing elevated levels of THM before they would face an increased risk of cancer, or problems with their liver, kidneys or central nervous system.
The BPW was notified in late November that a high THM level was detected in water samples taken last September. Ironically, THM levels approximately four times higher than those typically seen in the city’s water system turned up in a test conducted in September 2011.
In each instance the high THM level appeared in water leaving the treatment plant in Riverview Park.
“We didn’t expect to get this high result at the plant. Most of the time disinfection by-products grow in your system, and ours are too high leaving the plant on some of our tests and that’s what’s causing us problems,” said Hall. “We’ve been doing these tests since the late ‘80s and those are the only times leaving the plant we were anywhere near those results. It was twice as much as we’ve ever been.”
Since January 2012, the BPW has had an engineering firm working on a disinfection-by-product (DBP) study.
“Jar-testing results showed if we changed up some chemicals we’d get a better result,” said Hall, noting in a memo to the BPW Board that the latest abnormally high THM results could mean that the engineering firm “will need to go back to the drawing board.”
“A solution to allow us to meet the current and future disinfection by-products limits will have to be formulated and approved by the MDNR,” wrote Hall.
“We thought we had a plan, but this has thrown everybody off and we’re running out of time,” said Bob Stevenson, general manager of the BPW during last month’s board meeting.
According to Hall, more stringent THM regulations are due to take effect in October of this year.
Page 2 of 2 - In the MDNR’s eyes the BPW’s by-product levels have been too high in more than just September of the past two years.
“It’s a four-quarter running average. That’s what gets us,” said Hall. “It (September ‘11 level) was so high it didn’t matter if we had zeros the rest of the time, we were going to be out. That’s the way this one (September ‘12 test) was, too.”
While no fine has be levied against the BPW, that could be coming.
“We’re in discussions with DNR about that,” said Hall, noting a meeting with state officials is scheduled this week. “Basically we’re going to discuss a compliance schedule and with that could possibly be a fine.”