Ann Arbor, Michigan, Wastewater Plant to Receive Improvements

April 12, 2022

The city’s wastewater plant is designed to process nearly 30 million gallons of sewage per day

Ann Arbor, Michigan, is moving forward with a $15 million project at the city’s wastewater treatment plant along the Huron River.

The project will assist the plant with odor control, according to Michigan News.

Contracts for the improvement project were approved, including a $12.3 million construction contract with low-bidder Spence Brothers and a $1.2 million contingency fund for change orders.

The city’s wastewater plant is designed to process nearly 30 million gallons of sewage per day (mgd) from the city and portions of Ann Arbor, Pittsfield and Scio townships.

The plant’s headworks systems are the ultimate issue, reported Michigan News. According to Christopher Englert, a city wastewater treatment engineer, in a memo, he said that the equipment consists of: three mechanical bar screens, three screw compactors and two grit removal systems, including pumps, a swirl separator and grit washer. 

Bar screens were installed in 1989 and in 2000, according to Englert. The grit system also was installed in 2000 and has required pump replacement and rebuilding of its swirl concentrators and washers.

“In addition, WWTP staff have observed significant accumulation of grit downstream of the removal system that indicates the efficiency of the grit system is significantly diminished and negatively impacts downstream equipment and systems,” stated Englert in the memo. “The cost and frequency for maintenance of the headworks have increased and parts for the screening systems are no longer available and must be custom fabricated. These systems are nearing the end of their useful life and are in need of replacement to ensure effective screenings and grit removal.”

The project includes: replacement of the bar screens, grit-removal equipment, screening and grit processing equipment, and odor-control improvements.

An approximate $831,000 contract increase with Hubbell, Roth and Clark Inc. for engineering services was approved, totaling the firm’s contract to $1.6 million, reported Michigan News.

Another approximate $6.2 million in low-interest bonds was improved to finance improvements to the city’s water supply system.

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