South Sioux City New Wastewater Treatment Facility

HDR employee at the South Sioux Falls Wastewater Treatment Plant

South Sioux City New Wastewater Treatment Facility

Self Reliance Goals Led to the First AGS Facility in Nebraska

For nearly 40 years, the City of South Sioux City conveyed wastewater to Sioux City, Iowa, just across the Missouri River. In November 2019, South Sioux City received notice that its wastewater treatment contract with its sister city would be terminated or altered in four years. The primary concern revolved around the volume and composition of the wastewater.

In addition to residential waste, South Sioux City has a blossoming industrial sector that employs hundreds of people in the town of 14,000. At the same time, Sioux City’s 60-year-old plant needed significant renovations that were expected to raise rates on residential and industrial/commercial users by more than 30% in two years. This left South Sioux City with two options — build its own wastewater treatment facility or risk being cut off. The need for a new treatment plant stemmed from the fact that Sioux City refused to accept high-strength industrial waste from South Sioux City industries. 

HDR and the City completed a feasibility study to determine treatment options for a new direct discharge plant that serves industrial and potential domestic wastewater sources from the City. It was determined that the best alternative was a new greenfield plant with covered anaerobic lagoons followed by aerobic granular sludge, which is a novel treatment approach for high-strength industrial waste and was the more economical option over other technologies.

In addition to improved economics, the proposed technology was selected due to its compact footprint, energy efficiency, capacity for modular expansion to meet future growth, and nutrient removal potential. The 2-million-gallon-per-day facility provides additional treatment solutions to the industry and is the first AGS plant of its kind in Nebraska. The facility is flexible and scalable, offering options for future nutrient removal, planned integration and future industrial growth.

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HDR employee at the South Sioux Falls Wastewater Treatment Plant
South Sioux City

South Sioux City, NE
United States

2 MGD Facility


Honor Award (2024)
Engineering Excellence Awards
American Council of Engineering Companies of Nebraska