Wastewater Treatment Plant
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.
Treatment Process
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.