Madison Lake Regionalization + Elevated Storage Tank

Madison Lake, MN | Water


ISG worked with the City of Madison Lake to regionalize its wastewater treatment in coordination with the City of Mankato through the design and construction of a lift station and force main. Later, ISG helped the City design a new elevated water storage tank to support the growing community.


Based on an analysis of the City’s wastewater treatment options, the Madison Lake community determined that regionalization was preferred to the alternative of expanding its existing treatment plant or building a new one.


As the City engineer for the City of Madison Lake, ISG conducted an analysis of the City’s wastewater treatment options. This analysis concluded—and a number of public meetings confirmed—that the preferred solution was regionalization, rather than expansion of the City’s existing treatment plant or construction of a new plant. The Madison Lake City Council authorized coordination with the City of Mankato and Blue Earth County to facilitate implementation of the plan. An agreement was reached with the City of Mankato for the design and construction of the lift station and force main, and the treatment of Madison Lake’s sanitary sewer flows.

In addition to coordination with the City of Mankato and Blue Earth County, residents of a large unincorporated area around three regional lakes wished to pursue the option of forming a sanitary sewer district and participating in the construction of the regional force main. Many challenges were worked through to accomplish this, resulting in a project that not only serves the City of Madison Lake, but also will provide a sanitary sewer outlet for over 400 lake homes, many that have vulnerable individual treatment systems.

Key elements of the design include nearly five miles of force main, a regional lift station, decommissioning of the existing wastewater treatment plant, and modifications to the existing sanitary sewer collection system. By strategically modifying the existing system, flow was diverted from pipes that were functioning at or near capacity, allowing the City to prolong the lifespan of these facilities.

Elevated Storage Tank
As the City of Madison Lake has grown, the existing elevated water storage tank had become undersized to adequately serve the community. Additionally, the existing tower, constructed in 1911, had served the community well beyond its anticipated life cycle. Based on fire flow requirements and anticipated City growth, a 200,000 gallon spheroid tank was selected to replace the existing water tower. To fund the project, ISG assisted the City in securing low interest revolving loan funds from the Minnesota Public Facilities Authority. As this type of loan has specific requirements associated with it, the funding source was bid as a bid alternate. In this case, the low interest rate on the loan more than offset for the slightly higher construction cost. To meet the funding deadlines, the project design was expedited, resulting in an affordable project for the City.

The new tank is located at the site of the recently completed new municipal well and treatment facility. ISG was instrumental in helping to secure the property for the tower a number of years ago during the development of the adjacent property. The site is also proposed to be the site for a future public works facility. Having all of these facilities centralized allows for efficiencies for the public works staff.

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