Wastewater Treatment Facility Expansion for a More Resilient City

The new Columbus Wastewater Treatment Facility not only expands treatment capacity with a 3.2-million-gallon-per-day plant but also moves it from the riverside of the levee to the protected side. Completed in multiple phases over eight years, the plant offers excess capacity for an expanding city and protection from floods. 

The City set a goal to implement a cost-effective expansion that had the lowest life-cycle costs and thus incorporated an innovative, sustainable and operator-friendly design. Though not established at the beginning of the project, the Nebraska Department of Energy and Environment was expected to set limits on effluent nutrient discharge that would impact the new facility during its service life. To plan ahead, the HDR team provided sufficient space and designed the facility to accommodate future effluent nutrient limits, including using the existing multichannel aeration basin as a low dissolved oxygen zone to promote simultaneous nitrification-denitrification and allowing space for anaerobic basins to be constructed in the future for phosphorus removal. The effort to design to future regulations and expansion will prove beneficial industry-wide as limits and needs evolve. 

The benefits of moving the wastewater facility to the protected side of the levee were never more evident than in March 2019, when the Midwest experienced unprecedented flooding. During this time, the old facility was inundated by the adjacent Loup River. If the City had not moved the facility, it would have been unable to treat wastewater and potentially would have discharged millions of gallons of raw wastewater into the river — a catastrophic event that would have impacted human health and wildlife, degraded ecosystems and cost millions to repair systems. 

The plant’s essential nature to the City meant relocating it would be a daunting task. Both the existing plant and new plant had to remain operational throughout construction. Before the improvements, wastewater flowed to the unprotected site for pumping, screening and primary treatment, and then back to the protected side for secondary treatment before returning to be discharged into the Loup River. The endless back-and-forth created a sequencing challenge for the project team to use the existing pipes under the levee without drilling additional pipes. By using the existing pipes, the team minimized intervention by the U.S. Army Corps of Engineers and reduced the length of permitting. 

Through collaboration and innovation, the project team delivered a new, larger and protected wastewater treatment facility to the City on time and for over $6 million less than originally estimated.