The Wastewater Utility collects sewage from about 300 miles of pipe ("sewer main") distributed throughout Janesville. The wastewater treatment plant, located off Afton Road, tests and treats sewage in a manner that complies with all state and federal environmental regulations. Simply, the treatment plant is a man-made tool that imitates natural processes in the environment that clean up water. The treatment plant cleans the water faster than would occur in nature. Sludge, a natural by-product of the treatment process, is applied to approved farm fields whenever possible. This is the best use of this nutrient rich material. Clean water, which is the final product of the treatment process, enters the Rock River south of the plant.
A collection system maintenance crew cleans sewers with an emphasis directed toward the older and problem areas of the city. This crew also maintains the City's ten sewer lift stations. Emergency maintenance service is provided 24 hours a day, 7 days a week.
The Wastewater Treatment Plant has an average design wet weather flow of 19.8 MGD, a design peak flow of 25 MGD, and an average daily flow of 13 MGD which is discharged to the Rock River. The existing treatment facility is an advanced activated sludge treatment plant of bar screens, grit removal, primary settling, and activated sludge with ammonia removal. We treat Phosphorous biologically with the aid of sludge fermenters or with ferric chloride as our chemical back-up. We have final clarification, UV disinfection, and effluent cascade aeration. Solids are treated through anaerobic digestion with sludge thickening via centrifuges. The dry cake material is applied to DNR approved agricultural sites. A byproduct of the anaerobic digestion process is methane gas. We take the methane gas and condition it, run microturbines which produce heat and electricity. The electricity is sold back to Alliant Energy. In 2014 we generated around $209,000 worth of revenue and the heat captured is used to heat the digesters. In addition, we take the conditioned gas one step further and produce a compressed Natural Gas equivalent fuel that is able to be used in several City vehicles and our lawnmower. In 2014 we generated around 2,100 gallons of CNG which was used in the 5 CNG vehicles.
The collection system is comprised of ten small lift stations and about 300 miles of sewer main ranging from 4" - 72" diameter. The City is responsible for maintaining the mains primarily through rodding and water jetting, televising, chemical root treatment, lining and point repairing. Manhole rehabilitation is also performed on a contractual basis. In 2003, flow data maintenance data and collection system information were gathered to compose a Comprehensive Master Plan for the sanitary sewer system. This plan will identify areas of the collection system in need of upgrading because of undersized sewers, areas of high infiltration and inflow, and areas where growth will occur so future sewers can be properly sized. The study will also evaluate current operation and maintenance activities, engineering construction specifications, and the sewer use ordinance, making recommendations on how these activities can be improved. This Comprehensive Master Plan will be more than a planning document; it will also be the operation and maintenance manual for the collection system.
Process Control and Pretreatment Program
The Treatment Plant is equipped with a laboratory to perform all process control analytical testing (i.e. BOD, TSS, ammonia, phosphorus) and WPDES monitoring requirements including metals and TKN. The laboratory also conducts testing for industrial discharge compliance with the local and federal limits and is instrumental for implementation of the Pretreatment Program. The Wastewater Utility administers a Pretreatment Program that includes industrial inspections, discharge sampling and analysis, and compliance reporting to regulatory agencies. In addition to wastewater testing, the laboratory also performs the bacteriological sample analyses for the Water Utility.
The Wastewater Utility plant staff provides tours of the treatment plant processes and laboratory procedures to students, professional organizations, and interested groups. Contact the Wastewater Treatment Plant at 755-3120 for further information.