Sanitary Sewers & Treatment

The City provides many essential services that are out-of-sight and out-of-mind of residents. One of those services includes the treatment of your wastewater, which is channeled through a network of underground pipes to our wastewater treatment plant. In 1971 the City constructed its first wastewater treatment plant. That plant consisted of two primary clarifiers, two step feed aeration tanks and two final clarifiers. The plant was expanded in 1984 to accommodate Portage's growth. This expansion included a 3.5 million gallon Oxidation Ditch, four final clarifiers and the old step feed aeration tanks were converted into aerobic digesters. This expansion increased the capacity of the plant to 3.5 MGD. Also in 1984 a Tertiary Filter system was installed to handle solids that might pass through the final clarifiers. In 1984 a vacuum assisted drying bed was installed to dewater the biosolids that were produced in the facility. Starting in 1997 and ending in 1998, the plant was expanded from 3.5 MGD to 4.95 MGD with peak flows up to 15 MG. The expansion included a new bar screen and grit system at the headworks, 2 new final clarifiers and a 1.5 MG excess flow basin. The basin is to be used to handle the peak flows that the plant receives during large rain storms. In 2000, the old vacuum assisted drying beds were converted into a new maintenance shop.


Pretreatment identifies specific discharge standards and requirements that apply to sources of nondomestic wastewater discharged to a POTW (Publicly Owned Treatment Works). By reducing or eliminating waste at the industries ("source reduction"), fewer toxic pollutants are discharged to and treated by the POTWs, providing benefits to both the POTWs and the industrial users. The objectives of the program are to: prevent the introduction of pollutants into a POTW that will interfere with its operation, including interference with its use or disposal of municipal sludge, prevent the introduction of pollutants into a POTW that will pass through the treatment plant or otherwise be incompatible with it, and improve opportunities to recycle and reclaim municipal and industrial wastewaters and sludges. Ordinance Number 09-17 can be found in the files section.