Sloan LEMNA Covered Aerated Lagoon

Sloan, IA | Water


ISG worked with the City of Sloan to design a covered two-cell aerated lagoon with a polishing reactor and UV disinfection to modernize its wastewater treatment processes.


The City of Sloan's aging wastewater plant had outdated technology and had upgraded multiple times, but still had difficulty meeting IDNR requirements.


To solve the City of Sloan's wastewater treatment issues, ISG recommended a new system consisting of a covered two-cell aerated lagoon with a polishing reactor and UV disinfection. The design included a sewage grinder in the inlet structure for the lagoon. The existing collection system had two separate force mains—an existing 6-inch line and an 8-inch line installed with a bypass stormwater pump. These two lines were extended and flow meters were added to each force main to measure the flows coming from both systems.

ISG designed the covered aerated lagoon to handle the increased loading from the Infiltration and Inflow (I/I) and retain heat during winter months, which decreases the lagoon and polishing reactor footprint needed for the nitrification process. This benefited the City since there was a limited allowable footprint for the facility. The covered aerated lagoon system allows the City to attain the level of treatment required by the IDNR stream standards. The improvements also included design and construction of a UV disinfection system to comply with E. coli compliance requirements. Furthermore, this system is adaptable to meet potential future regulations.

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