The City of Eaton Rapids Wastewater Treatment Plant (WWTP) is designed to treat a Total Average Daily Flow of 1.1 MGD (Million gallons per day) and a Maximum Daily Flow of 2.1 MGD.  The Peak Hourly Flow rate is 3.2 MGD.

Wastewater is delivered to the WWTP via the sanitary sewer collection system.  The raw wastewater is directed thru “preliminary treatment” for removal of sticks, rags, plastic and rubber materials that may clog or damage pumps.  Sand and grit are also allowed to settle out of the wasteawter flow to prevent excess wear on plant pumps and piping.

The wastewater flow is then directed into an anaerobic selector tank, along with return activiated sludge, for enhanced biological phosphorus removal.  The flow is then pumped into Complete Mix Activated Sludge aeration tanks, for “secondary treatment”.  Subsequent flow enters the final clarifiers where sludge floc is teaming with micro-life and allowed to clarify from the wastewater.

The clarified wastewater flow is then disinfected, by use of ultra-violet lamps, before being discharged into the Grand River.


The City of Eaton Rapids Wastewater Treatment Plant (WWTP) was constructed in 1954.  It was designed  as a “primary” treatment plant.  As such, its main purpose was to skim off floating materials and allow solids in the wastewater to settle out.  Chlorine was then added for disinfection.  The treated wastewater flow was then discharged into the Grand River.

The Federal Water Pollution Control Act was passed by the United States Congress on October 18, 1972.  This Act established the National Pollutant Discharge Elimination System (NPDES) Permit Program.  States were allowed to administer the Permit Program after federal authorization.  The main components of the program – effluent limitations, water quality requirements, the Permit Program itself and other initial groundwork is still in place today.

Upgrades were completed at the Wastewater Treatment Plant in 1978 which provided “secondary” treatment capabilities.  Secondary treatment follows primary treatment and is used to convert dissolved or suspended solids into a form which is easier to separate from the water being treated.  This process is normally a type of biological treatment, followed by final clarification.  The City of Eaton Rapids Wastewater Treatment Plant uses a biological complete mix activated sludge process for secondary treatment.  The completed renovations provide the required treatment to satisfy the more stringent NPDES discharge permit requirements.  The designed average flow rate thru the plant was 1.2 million gallons per day with a maximum flow rate of 2.0 million gallons per day.

After operating 24 hours a day, 365 days a year, for 28 years, the Wastewater Treatment Plant equipment became worn out and obsolete.  Persistent efforts were made by the City’s Wastewater Treatment Plant Staff to keep the process equipment in operation well past normal service life expectancy.

A City Wastewater Millage Election was held on February 10, 2004, to ask the citizens of Eaton Rapids for their support of the critical public works needs.  The overall project costs for renovations would be $9,800,000.  Citizens approved to pay for the project by means of an additional millage on all non tax-exempt property.

The most recent Wastewater Treatment Plant upgrade began in October 2004 and was completed in April of 2007.

The scope of the plant upgrade consisted of:

  • Replacement of worn out equipment
  • A sanitary sewer evaluation study
  • Construction of a new secondary clarifier
  • Construction of a new equalization tank for temporary storage of high storm flows
  • Installation of new process instrumentation
  • Installation of a new computerized Supervisory Control and Data Acquisition (SCADA) system.

Immediate benefits were seen in overall plant operations through equipment reliability, energy efficiency, and an improved safe work place for plant staff.

The City of Eaton Rapids Wastewater Treatment Plant is fully capable of providing the treatment necessary to meet or exceed its NPDES permit discharge requirements and therefore help protect our natural resources today and for many years to come.

Meet Your Plant Staff

Contracted with Hughes Environmental Services, Inc.

Wastewater Operators:

Wayne Verhelle, Scott Perry, Jeremy Kuykendoll and Everette Fish

Plant Tours:

The staff are very proud of the Treatment Plant and the many recent upgrades that have been added thanks to the citizens of Eaton Rapids.  If you would like to arrange a tour of the facility, please contact Staff at (517) 663-8118, ext. 8118. They will be glad to show you around!