Gallatin’s new water treatment plant opened in 2018. The construction was done by David E Ross Construction Company, which bid $4,987,000 to build the new plant. The last part of the project, according to Gallatin City Administrator Tony Stonecypher, involved inside work to install electricity, plumbing and control panels.
How is raw water made clean and safe to drink at the treatment plant?
The Water Treatment Process: The Gallatin Water Treatment Plant (WTP) is a lime-softening process, which means hardness in the water is removed from the water through the addition of lime. Lime softening is a common treatment for groundwater. Gallatin’s water source is groundwater from three wells located approximately three miles east of Gallatin along Highway 6. Once the groundwater is pumped to the treatment plant, complete lime softening WTP stages include aeration, coagulation /flocculation/sedimentation, recarbonation, filtration, and disinfection. The following provides a brief description of each stage:
Aeration: The incoming raw water is cascaded through an aerator to strip dissolved carbon dioxide (CO2). Stripping the CO2 lowers the amount of lime required later in the treatment process.
Coagulation/Flocculation/Sedimentation: Following aeration, the water is routed to a solids contact clarifier for hardness removal. Lime and the coagulant aluminum sulfate is added and the water is gently mixed, aggregating the small precipitated particles together to form larger precipitates called flocs (flocculation). Once large enough, the flocs settle by gravity to the bottom of the clarifier and are removed (sedimentation).
Recarbonation: After adding lime, treated water will generally have a pH greater than 10. It is necessary to lower the pH to stabilize the water and prevent deposition of carbonate scale on distribution piping. Recarbonation is achieved through the addition of CO2, a common process used to reduce pH.
Filtration: Following recarbonation, filtration removes any unsettled lime floc and other partials that may be present in the treated water.
Disinfection: Chlorine is added to the water to eliminate any remaining pathogens.
Clear Well: Once treated, the water is routed to a clear well onsite, which is a large concrete storage tank. Water in the clear well is pumped to the existing 250,000 gallon water tower, located on the western edge of town, and then routed through the existing approximate 45 miles of distribution main to the City’s end users.