Donohue & Associates and the City of Two Rivers, Wisconsin, received an Honor Award in the 2002 ACEC Wisconsin Engineering Excellence competition. The award recognizes the evaluation, design, and construction-related services of ultraviolet disinfection facilities and an aeration basin conversion at Two Rivers’ wastewater treatment facility.

Facing the need for additional capacity and stricter regulations regarding the use of chlorine, the City worked with Donohue to develop solutions to save money and valuable green space at the treatment facility. Prior to this project, the City used gaseous chlorine to disinfect its wastewater, which posed safety concerns and required additional measures to meet new U.S. EPA regulations. The City installed an ultraviolet (UV) disinfection system and uses a state-of-the-art design; it is one of the first in the nation to feature this technology.

Available space on the site for new UV facilities was severely limited. The City and Donohue developed a solution whereby the existing chlorine storage room was converted to the UV facilities. Another challenge was the limited capacity for the aeration process, which was adversely affecting performance. By converting the unneeded chlorine contact tanks to aeration basins, aeration capacity expanded by 60 percent without constructing new facilities.