The Spearfish Wastewater Treatment Plant, located three miles north of Spearfish, was built in 1982 with a design flow for treatment at 850,000 gallons per day. The majority of the wastewater flows by gravity to the facility. The plant capacity was updated in 1993 to treat up to 1.4 million gallons per day (MGD). Following the 2008-2009 upgrade, the plant capacity is 1.65 MGD.
The treatment process, known as “Activated Sludge,” is followed by secondary clarification, tertiary filtration, and is disinfected before following the 3 mile outfall line to Spring Creek. The by-product of the wastewater, referred to as “Biosolids,” is currently disposed according to federal and state regulations.
The facility is currently operated by the plant Superintendent and four full-time certified operators. The plant consistently operates within the discharge permit parameters. Since the start-up in 1982, the facility has been awarded the Environmental Protection Agency (EPA) Region VIII Award for Excellence in Operations and Maintenance twice and also the EPA National Award for Excellence in Operations and Maintenance in 1986.