The clinic cites patient demand for the expansion.
Wausau Daily Herald Media reports the clinic would add about 75,000 to 110,000 square feet to its present facility, including a small hospital to support its plans for new specialty services. The facility's new addition is planned for south of the current site.
Aspirus Clinics president Dean Danner estimates construction to begin by spring 2015 and the new facility to open by the end of 2016. The project would require approval by the city's planning commission and City Council.
The clinic has been in operation for 57 years and serves about 10,000 patients a month.