• Wastewater Treatment Plant                                                                                       Departments > Wastewater Treatment
  • 735 E Washington Street
  • 419-592-3936
  • Monday-Friday | 7:00AM-3:00PM

Wastewater generated in Napoleon is collected by a combined collection system on the West and South sides of town and a separated system in the North, Central, and West sides of town. The wastewater is transported through a 35 inch by 45 inch brick combined sewer and a 12 inch force main under the river from the Palmer Ditch lift station.

The Napoleon Wastewater Plant is a trickling filter plant which includes phosphorus and grit removal facilities, primary sedimentation, nitrification, reaeration basin, final settling, ultraviolet disinfection and sludge disposal.

The sludge disposal equipment consists of a primary digester, two secondary digesters, two belt filter presses and a 258,000 gallon sludge lagoon. Digested sludge is land applied for use as a soil conditioner.

Combined Sewer Overflow (CSO)

What is a CSO?

During dry weather and small wet weather events (i.e., rainfall and snowmelt), combined sewers are designed to transport all flows to a treatment plant. During larger wet weather events the volume of storm water entering the combined sewer system may exceed the capacity of the combined sewers or the treatment plant. When this happens, combined sewers are designed to allow a portion of the untreated combined wastewater to overflow into the nearest ditch, stream, river or lake. This prevents the rupturing of pipes, backing up of sewage into basements, and/or flooding of streets. The locations where these discharges of untreated combined wastewater occur, as well as the discharge events themselves, are known as Combined Sewer Overflows (CSOs). CSOs are located at various locations along combined sewers, and are unique to each system.

Why are CSOs a concern?

CSOs contain not only storm water but also untreated human and industrial waste, toxic materials and debris. This is a major water pollution concern for cities with combined sewer systems. CSOs are among the major sources responsible for beach closings, shellfishing restrictions, aesthetic impairments and other water body impairments. Additionally, contact with discharges from CSOs can have adverse effects on human health. A December 2001 report to Congress cited the Center for Marine Conservation as stating that, "some of the common diseases include hepatitis, gastric disorders, dysentery, and swimmer's ear. Other forms of bacteria found in untreated waters can cause typhoid, cholera, and dysentery." (Report to Congress on Implementation and Enforcement of the CSO Control Policy, December 2001, EPA 833-R-01-003)

When should CSOs be avoided?

CSO outfalls and their receiving waters should be avoided during and immediately after any wet weather event (i.e., rainfall and snowmelt). Additionally, these locations should be avoided any time a discharge is observed from the outfall pipe regardless of weather conditions.

Ohio EPA CSO Program Contacts

  • Sherer, Erin - (614) 644-2018
  • Brumbaugh, David - (614) 644-2138


Plant History


The original plant was constructed in 1958 and consisted of grit removal, primary settling, a trickling filter, final settling, disinfection, anaerobic digestors, and sludge drying beds. The 1982 rehabilitation project added a second grit removal channel, converted the final settling tank into a primary settling tank, built a second trickling filter, and two new final settling tanks to add capacity and provide redundancy. Two more anaerobic digesters and a sludge lagoon were built to increase sludge digestion and handling capacity prior to disposal.  

In order to meet new NPDES permit requirements, a $3.8 million expansion and rehabilitation project was started in the summer of 1997 and finished in November of 1998. The project increased the hydraulic capacity of the plant from 6.0 MGD to 7.5 MGD to provide more capacity for wet weather flows.

The rehabilitated plant also provides for ammonia removal and dechlorination of plant effluent. The project also included the replacement of mechanical screens with two new traveling screens; the replacement of sludge collection equipment in the two existing primary tanks; and the addition of a third final settling tank and sludge pump, reaeration tanks, and a blower building. Facilities for feeding chlorine gas, alum, and sodium bisulfate in the process stream were also added.

In order to cut costs, the rock media trickling filters were increased in height from 6-foot sidewalls to 32 foot and converted to bio towers with plastic media for ammonia removal and aluminum dome covers were also installed to protect the media.

In 2010 a 2.5 MG Equalization Basin and Associated Facilities were constructed. This project was the single largest capital project ever undertaken by the City and is the cornerstone of the Long Term Control Plan. Included was the 2.5 MG EQ Basin, installation of Ultraviolet (UV) Disinfection units and new Effluent pumps. The EQ Basin provides the Treatment Plant with additional capacity for capturing and treating wet weather events.  The UV Units replaced the need for chlorine disinfection; the Effluent pumps are needed when the Maumee River is in flood stage and the Treatment Plant cannot gravity discharge.


Treatment Process / Design

The treatment process used at the Napoleon Wastewater Plant consist of the following basic stages:

  1. Screening: removes coarse and stringy materials.
  2. Detritor: removes sand and grit.
  3. Primary Settling Tank: removes suspended solids.
  4. Biotowers: BOD removal and nitrification.
  5. Secondary Settling Tanks: removes additional solids and phosphorus.
  6. Ultraviolet Disinfection: Disinfects Plant Effulent
  7. Sludge Digestion: removes gas and odors and stabilizes sludge.
  8. Belt Filter Press: For dewatering of digested sludge.

Average Daily Flow: 2.6 MGD
Maximum Daily Flow: 4.7 MGD
Peak Hydraulic Flow: 7.5 MGD
Influent BOD at Average Flow: 4,770 lbs.
Influent SS at Average Flow: 4,987 lbs.
Influent Phosphorus at Average Flow: 163 lbs.


Equalization Basin:

  • 3-66" Screw pumps @ 10 MGD each

  • 120' x 240', with 12.5' water depth

  • Total capacity 2.5 MG


Primary Tanks:

  • 2 -@ 45 ft. diameter, with 8.5 ft. water depth

  • 13,512 cf each, 101,070 gal. each or 202,140 gal. for both tanks

  • 141.3 linear feet of weir per tank



  • 2 - @ 55 ft. diameter, 30 ft. depth of media

  • 268,488 sf and 142,560 cf of media (71,239 cf per filter)

  • 297 blocks of media per layer, with 30 layers per filter


Aeration Basin:

  • 30 ft. x 6 ft. x 9.5 ft. = 1710 cf

  • 1710 cf x 7.48 gal/cf = 12,791 gal. x 2 = 25,582 gal. total


Final Tanks:

  • 3 - @ 60 ft. diameter, 12 ft. water depth

  • old final tanks - 2 @ 33,912 cf. 253,789 gal./each

  • new final tank - 1 @ 33,912 cf. 253,662 gal.

  • 188 linear feet of weir per tank

  • 761,240 gal. Total Final Settling


Primary Digester:

  • 55 ft. diameter, 20 ft. water depth

  • 47,500 cf and 355,250 gal. capacity


Secondary Digester:

  • 55 ft. diameter, 20 ft. water depth

  • 55,755 cf and 417,056 gal. capacity


Belt Filter Building:

  • 2 - 1.5 Meter Presses

  • 280 - 350 lbs. dry solids/hr.

  • 70 ft. x 140 ft. sludge storage area


Emergency Power:

  • 275 KW Generator with automatic transfer switch - Plant

  • 500 KW Generator with automatic transfer switch - EQ Basin