Combined Sewer Overflow

Combined Sewer Overflow (CSO) Control Program
When the original sewer system was constructed in the City of Manistee several decades ago it was a combined sewer system. At the time it was installed, this was a state of the art system and was a vast improvement over the open ditches that preceded it. A combined system transports sewage and stormwater in the same pipe.

When it rains and stormwater enters the sewer system, the hydraulic load becomes too high to sustain treatment. The Wastwater Treatment Plant (WWTP) is then forced to regulate the amount of flow entering the plant, which causes the excess inflow to be discharged at CSO outfalls in the city.

In 1996 Manistee entered into a Final CSO Control Program with the Michigan Department of Environmental Quality (MDEQ) to provide for the elimination or adequate treatment of the combined sewage discharges containing raw sewage, to comply with the Water Quality Standards at times of discharge. When the program was created the city had four active CSO outfalls, they consisted of:
  • Outfall 003 located at First Street and Cedar
  • Outfall 004 located at Water Street and Cedar
  • Outfall 014 located at River Street and Jones
  • Outfall 018 Located at Fifth Street and Ramsdell
The program was approved with the following timeline:
  • On or before December 31, 2011, the city shall complete construction facilities for the elimination of overflows from Outfall 014.
  • On or before December 31, 2016, the city shall complete construction facilities for the elimination of overflows from Outfalls 003, 004 and 018.
  • By the end of 2011 the city will have completed all combined sewer separation projects in compliance with the approved control plan.
  • The last two major parts of this process are the Jones Street district, which was separated in 2010, and the Cedar Street district, which is being separated in 2011.