On Tuesday, August 3, the City of Pipestone Water Treatment Plant was honored with the Chloride Reduction Leadership Award at the 2021 Salt Symposium. This award was given for their efforts to lower chloride levels in water levels, also reducing chloride concentrations in the city’s wastewater discharge.
The City of Pipestone faced a chloride limit at its wastewater treatment facility. The chlorides were not naturally present in the groundwater but were being added by using zeolite water softeners in homes and businesses throughout the city. With support from the city council and city administrator, the City of Pipestone Water Department staff and Bolton & Menk developed a new centralized lime softening facility to provide hardness removal without the use of ion exchange softeners and salt regeneration. The new facility softens the water to 4 to 5 grains of hardness, compared to the previous hardness of 40 grains. The improved water quality has allowed users to either turn off or drastically reduce salt use in home water softeners. The improvements have reduced chloride concentrations in wastewater discharge to well below the NPDES permit limit. This improves stream water quality in Pipestone Creek, home to the endangered Topeka Shiner minnow.
The water treatment plant was unique in using potable water treatment to meet a wastewater limit. The state agencies, Minnesota Department of Health, and Minnesota Pollution Control Agency worked together in an unusual arrangement that saw grants traditionally used at wastewater plants being used for the Pipestone Water Treatment Plant along with traditional water plant financing.
The city has ensured the project was successful via working on communication regarding the softer water and turning down water softeners. The city has direct communication with many of the larger industries to encourage adjusting softeners. Information was published along with a short video on the local cable channel for homeowners. Even though the city is meeting its limits, they are going one step further to provide home inspections by plumbers to ensure the running softeners are properly adjusted and not using excess salt, costing the consumer money and harming the environment.
The project has been operating for 2 years and has initially reduced chlorides by nearly 50 percent. That is equivalent of approximately 2,000 pounds of salt per day.
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