Water plant averts service interruption

When Maryville completed construction of two 750,000-gallon auxiliary water towers in 2011, city officials said the new tanks would help ensure that faucets kept running in the event of an emergency.

As things turned out, that bet paid off this fall when the municipal water treatment plant experienced a near-catastrophic computer failure.

Steve Guthrie of PeopleServices, Inc., which runs the water plant for the city on a contract basis, told the Maryville City Council this week that water stored in the new towers gave his team the time it needed to fix the problem and bring the plant back online without an interruption in service.

What happened was this. On Oct. 24, the computer and power supply used to control the plant's filter membranes failed. The membranes are essential to the water purification process and are capable of removing particles as small as 0.1 microns — a micron being equal to one millionth of a meter.

Making sure that water flows through the membranes at the correct rate and pressure is crucial to their functioning properly, and controlling that process  is virtually impossible without a computer, Guthrie said.

In order to make emergency repairs, it was necessary to order new equipment and request trouble-shooting services from a third-party vendor.

The replacement equipment was installed on Oct. 28, but thanks to the new towers, Guthrie told the council, taps in Maryville kept running while the plant was shut down for repairs.

Though the water stayed on, the fix wasn't exactly cheap, and on Monday the council accepted the $21,000 bill for emergency repairs and new hardware. In addition, the council will spend another $6,400 for a new back-up computer and upgraded data hookups to prevent a similar crisis in the future.

Guthrie said the current aging back-up system is "buggy" and unreliable and will be declared ineligible for support by the manufacturer in March.

Though significant, the cost of repairing and upgrading the system — known as a programmable logic controller — is small potatoes compared to the filtration membranes it is designed to operate and protect.

Guthrie said that proper control of water flow and other factors can extend the life of the $2 million membranes, which, when functioning correctly, are capable of producing up to five million gallons of drinking water daily for brief periods and more than three million gallons a day on a regular basis.