PHOTO: City of Franklin employees Michelle Hatcher, Russell Sullivan, Eric Stuckey and Mark Hilty stand at the entrance to the water treatment facility’s new building on Wednesday, June 20, 2018. / Brooke Wanser
By BROOKE WANSER
A $14 million upgrade to Franklin’s water treatment plant off Lewisburg Pike has just been completed, bringing a new building, water filters, and state-of-the-art equipment to the city.
Outside the plant, originally built in the 1950s, City Administrator Eric Stuckey explained how the upgrade was conceived as part of the integrated water resource plan in 2010.
The water resource plan is a 30-year, comprehensive outlook including stormwater management, wastewater treatment, and modeling the city’s impact on the river.
Updating the water treatment plant, Stuckey said, was in the first tier of projects. Construction began in the fall of 2015, finishing up earlier this year.
The plant off Lewisburg provides approximately one-third of Franklin’s tap and drinking water, Mark Hilty, the assistant city administrator for public works, said.
The rest of the city’s water comes from the Cumberland River, via the Harpeth Valley Utilities District, and the Mallory Valley Utility District.
Even after the 2010 flood, “we were able to continue operating,” Stuckey said. “We had a very minimal downtime at this plant in the midst of that flood, and that wasn’t necessarily the case with other utilities.”
Plant Superintendent Russell Sullivan, who has worked for the water department since 1988, said after the heavy rains, the plant was back online within 16 to 18 hours.
While other plants were down for longer, “that’s where we saw firsthand the benefit of having redundancy, in terms of water sources and more than one water source,” Stuckey said, citing the economic security.
Even as the Harpeth River looks drier than usual, Stuckey said the city is cognizant of seasonal volume changes, not drawing water from the river when oxygen and flow levels are low.
The biggest change to the plant comes in a new building, which hosts an entirely new filtration system.
Water from the Harpeth River is pumped into a 114 million gallon reservoir behind the facility. An old, above ground pump station on the same side of Lewisburg as the river has been replaced with an underground pump station across the road. The plant treats about 2.99 million gallons of water each day.
Water is pumped into the pre-treatment tank, where sodium permanganate, an inorganic compound, is added. The compound oxidizes algae and other organic products, and helps remove any unpleasant smell or flavor.
Then, the water is rapidly mixed for 60 seconds inside a flash mix box, where the compound is dispersed evenly throughout the water.
Water is then distributed into the flocculation basins, where floc, the larger, heavier formations of product, are created when the positive and negative elements bind together.
In the sedimentation tank, the floc settles to the bottom of the tank, where it is removed by sludge vacuums. In the old process, the water is distributed through a plastic membrane before entering the facility’s new building. By the time it comes out of this tank, it is about 30 percent clean.
Water bypasses the old facility, entering instead into rocket-like Suez filter cartridges, which have a hollow, fibrous membrane. Water leaving this filtration system is about 90 percent clean, clean enough to drink, Hilty said.
Still, water is piped through a large blue pipe, where hydrogen peroxide is injected. Michelle Hatcher, the city’s water management director, said Franklin is the first plant in the state to add hydrogen peroxide; it is scientifically proven to help any water with taste or odor issues, which has been a complaint of some residents in recent years.
The water is then piped through a UV light system so bright, “you can get a tan in about two seconds, you’ll sunburn in about three,” Sullivan said.
The water goes into a tank, where it is dripped over charcoal as a last filtration step. In the old building, the water used to be filtered through sand.
Finally, the water is piped outside, where is goes into an underground holding tank for distribution to residents in the area.