The city of Ann Arbor's sanitary sewer system includes a wastewater treatment plant and eight sewage lift stations located around the city. The plant, located at 49 S. Dixboro Road, is a continuous, 24-hour a day, seven-day a week operation.

According to the city of Ann Arbor's official website: "The current WWTP has a design capacity of 29.5 million gallons per day (MGD), and consists of an older West Plant (constructed in the 1930s) and a newer East Plant (constructed in the late 1970s). The facilities renovations project consists of two phases. Phase I includes design and construction services for demolition of two existing structures. Phase II is the larger of the two projects and includes rehabilitation of the East Plant (constructed in the late 1970s) and demolition and reconstruction of the West Plant (constructed in the 1930s). The current contractual final completion date for this project is September 19, 2017. Due to construction and safety concerns, tours of the wastewater treatment plant are currently unavailable. Opportunities for tours may resume following construction at the plant, in 2017-2018."

Waste Water Treatment Plant: Timeline

• 2015-06-01 The Waste Water Treatment Plant appears on the June 1, 2015 agenda of the Ann Arbor City Council so that the Council can approve a contract worth an estimated $218,800 a year purchase of polymer from Polydyne Inc. for the Wastewater Treatment Plant. The dollar figure corresponds to approximately 30,000 gallons. According to the staff memo accompanying the resolution, the WWTP has two gravity belt thickeners and three dewatering centrifuges to improve the plant's ability to thicken and dewater biosolids for land application or landfill disposal. Biosolids must be conditioned with polymers to ensure functionality and optimal performance of the gravity belt thickeners and centrifuges, thereby enabling cost effective management of biosolids. According to the memo, several years ago, plant staff worked with vendors to test various polymers best suited to the WWTP's biosolids thickening and dewatering equipment. Based on these test results, staff advertised for two specific polymers under a previous Invitation to Bid.
• 2015-06-01 The Waste Water Treatment Plant appears on the June 1, 2015 agenda of the Ann Arbor City Council so that the Council can approve a one-year contract with possibly three one-year renewals, worth an estimated $50,000 a year for the purchase of ferric chloride from Kemira Water Solutions, Inc. (Kemira). The WWTP uses ferric chloride for the removal of phosphorus to levels specified in its National Pollutant Discharge Elimination System (NPDES) permit. Especially during summer months, phosphorus removal becomes critical and the addition of ferric chloride improves the plant's ability to remove phosphorus from the wastewater. Violation of NPDES permit requirements could result in significant fines of up to $25,000.00 per day per occurrence being imposed on the City by the Michigan Department of Environmental Quality. The WWTP advertised an Invitation to Bid (ITB) to supply ferric chloride required by the plant in ITB-4385. There were two respondents to this ITB: Kemira Water Solutions, Inc. $388 per dry ton delivered; and PVS Technologies, Inc. $517 per dry ton delivered.

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