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The City of Sloan's aging wastewater plant had outdated technology and had upgraded multiple times, but still had difficulty meeting IDNR requirements.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

Market News

ISG Bolsters Connectivity with Strategic Telecommunications Expertise Addition

May 29, 2020 (Green Bay, Wisconsin) – ISG, a professional design and engineering firm that serves both diverse markets and vast geographies, recently expounded upon its progressive strength and business unit diversification by welcoming long-time telecommunications leader Dan Nelson, PE. Based out of the Green Bay office, Dan and his team will continue to advance connectivity and further support clients on a national level.
Read More

ISG Adds Minneapolis Architecture Expertise

March 20, 2020 (Minneapolis, Minnesota) – In an effort to strengthen services for a wide range of partners in the Twin Cities and across the Midwest, ISG is joining forces with Architects Rego + Youngquist, LLC. (ARY) of St. Louis Park, Minnesota. As a premier provider of design services in the education, civic and cultural, and healthcare markets, ARY’s talented professionals will add a wider breadth of expertise as they are integrated into ISG’s multi-disciplinary team.
Read More