Saturday, May 14, 2011, was a perfect day for an “indoor outing” with a cold front the day before bringing in cloudy skies and cool brisk northwest winds. Seven members of the Topeka Group were treated to twin tours, one of the Topeka Water Treatment Plant and the second of the Wastewater Treatment Plant. Those curious about where drinking water comes from and where it goes where able to see the processes first hand.
The Topeka Water Plant processes an average of 40 million gallons of water a day, and has a capacity of in excess of 60 million gallons. Water is drawn from the Kansas River by two large intake structures, then pumped into large circular concrete tanks where mud and other debris settles out in a two-stage process. A chlorination process kills microbes, and after that, fluorine is added, for the purpose of retarding tooth decay. The water is then softened to provide for a slightly alkaline PH, and is then sent to two more large concrete tanks for final purification. The process occurs on a 24 hour “roller coaster” schedule, with overnight filling of water towers in Topeka to provide for a gradual drop of water levels in those structures during the day when water usage increases. Plant operators monitor the treatment systems as well as security gates and cameras around the clock.
The process is essentially reversed at the wastewater treatment plant. Sanitary sewers operate primarily by gravity, but at intervals, pump stations lift the sewage so that it can continue its trek toward the plant. Several collector stations throughout the city serve as junctions for incoming sewers, all of which eventually lead to one of three plants in Topeka. The main plant in Oakland, which we toured, can handle up to 100 million gallons a day, but the average is about 14 million gallons. The treatment structures look somewhat similar to those we saw earlier at the water plant, with the process being in three stages: settling out of the solid waste, followed by the introduction of microbial bacteria which “eats” the sugars and other dissolved particles in the waste, and with the final stage being ultraviolet radiation of the sewage to kill any remaining pathogens. The water remaining is then returned to the Kansas River.
The solid waste is stored in a bunker-like structure for a short time with bacteria continuing to work on the sludge, with methane being one of the by-products. Some of this is used to heat parts of the plant. At present, the rest is flared, although there are plans to eventually clean the methane to allow it to be used to power city vehicles. The remaining de-watered sludge, after this process, can be used as fertilizer and sold by the city to farmers at a nominal price. The entire process takes less than 24 hours.
Both plants are revenue sources for the city of Topeka and do not use tax dollars to operate. At one time, all of the revenue from the water plant went back into infrastructure improvements, but over the years, the money has been transferred to general funds to help finance overall city operations, allowing the city to enjoy lower taxes. Does this have a familiar ring?
By Paul Post, Topeka Group Outings Chair