January 16, 2020 - During follow-up wet weather inspections on Wednesday, Jan. 15, 2020, City of Ann Arbor Public Works staff located two sanitary sewer manholes that showed evidence of surcharging sewage into both Malletts Creek (near Redbud Park) and Swift Run Creek (near Hogback Road). Upon further investigation, the cause in both locations was determined to be a sewer capacity issue due to high flows during a wet weather event.
An estimated 4,500 gallons of untreated sewage was surcharged from a sanitary sewer manhole into a grassy open space, draining overland into Swift Run Creek.
An estimated 300 gallons of untreated sewage was surcharged from a sanitary sewer manhole into a grassy open space, draining overland into Malletts Creek.
In both locations, the affected ground area was cordoned off and limed, to neutralize any bacteria that remained on the ground surface. Signage was placed in areas that a person or pet may encounter.
The capital improvements to alleviate the capacity issue in the sanitary sewer system have already been underway — with construction starting in mid-2019, and will be complete in summer of 2020.
In accordance with regulatory protocols, City of Ann Arbor staff has notified the Michigan Department of Environment, Great Lakes and Energy.
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