An estimated 1,800 gallons of untreated sewage water leaked into a grassy open space in the University of Michigan Arboretum on Wednesday afternoon after a sanitary sewage pipe became blocked by gravel.
According to the city of Ann Arbor, further investigation found damage to a city-owned manhole structure from University grounds maintenance activities. The damage caused an opening for gravel to enter the sanitary sewer that ultimately resulted in the blockage.
City of Ann Arbor Public Works staff were notified of the leaking manhole at approximately 2 p.m. on Wednesday. In partnership with the University, they immediately removed the gravel from the pipe and the area was cleaned within 24 hours of the incident. The affected area was cordoned off and limed to neutralize bacteria that may have remained on the surface.
Staff of the city of Ann Arbor notified the Michigan Department of Environment, Great Lakes and Energy as required by regulatory protocols.