HBPW takes water tank out of service to lessen water’s ‘age’
Unlike a bottle of wine that improves with age, the same apparently is not true when it comes to water. The Hannibal Board of Public Works (HBPW) recently took one of its storage tanks out of service in an attempt to lessen the age of the water that was being provided a portion of its service system.
According to Heath Hall, director of operations for the HBPW, the action was taken on the recommendation of Black and Veatch (B&V) Engineers, which is familiar with the city’s water-supply system.
“They were suggesting that (taking a tank out of service) might work in the future to reduce the age of the water in our system, which reduces disinfection byproducts (DBPs) potential,” he said. “We took one of our tanks out of service, trying to reduce the water’s age, and it has.”
B&V’s suggestion was implemented, according to Hall, because a “main interest” of the HBPW is being in compliance with the Environmental Protection Agency’s maximum contaminant levels of regulated DBPs. DBPs are formed when chlorine combines with naturally occurring organic matter found in water.
For its water-tank “experiment” the HBPW chose a low pressure zone in the water system — mostly south of U.S. 36 and east of U.S. 61, including the downtown area — that is served by tanks located on Clinic Road (1 million gallons capacity) and Warren Barrett (500,000 gallons capacity). The decision was made to drain the tank on Clinic Road.
“The larger the tank the quicker turnover in the tank and water in the system, and therefore less water age,” said Hall, noting that water temperature can also factor in the formation of DBPs.
Preliminary results have been positive, according to Hall.
“We’re seeing better residuals at the bottom of the tank, seeing more turnover in the tank, sometimes too much turnover,” he told the HBPW Board at its Aug. 15 meeting.
If the Warren Barrett tank drains too quickly the HBPW can open a valve and quickly fill the tank.
“We’ve been trying to operate with it (valve) closed, but we had to open it a couple of times because the tank drained faster than we wanted it to,” Hall said.
Despite the positive results after draining the Clinic Road storage tank, Hall called the action a “temporary trial.” Consequently, there are no plans to either move or sell the now empty water tank on Clinic Road.
“I assume we will still need it in the future, especially since it was recently updated,” said Hall. “The Warren Barrett tank is due for a repainting in the next few years. Having the backup will make the down time for painting more convenient.”
No special maintenance is required while the tank sits empty.
“When it goes back into service it will have to be cleaned and disinfected,” said Hall.
The Clinic Road storage tank has been a part of the Hannibal landscape for around a half century.
“Originally constructed in the 1960s, it was completely redone — painted inside and outside, and installed new safety features and vent — in 2008. That is when the America’s Hometown logo was installed as well,” said Hall.
Reach reporter Danny Henley at firstname.lastname@example.org