April 7, 2016 - At approximately 11 a.m. on Wednesday, April 6, 2016, a City of Ann Arbor Public Works crew member discovered a sanitary sewer manhole that was overflowing in a wooded area near the intersection of Washtenaw Avenue and Huron Parkway. The cause of the overflow was determined to be roots that had grown through the sanitary sewer pipe, blocking flow. City crews immediately responded and removed the roots from the pipe to restore proper the pipe to functioning order and end the overflow. Upon further investigation, evidence indicated that the overflow had been occurring for about two weeks. It's estimated that some 400,000 gallons overflowed into Malletts Creek, equivalent
to 20 gallons per minute*, whereas the median flow of water in Malletts Creek
during this period was 28,276 gallons per minute*.
There are no communities downstream of the plant that withdraws water from the Huron River for drinking purposes. In addition, there are no health risks posed by this overflow to those using the Huron River for recreational purposes, due to the dilution effects.
In accordance with regulatory protocols, City of Ann Arbor staff contacted the Michigan Department of Environmental Quality to inform them of this unfortunate incident. City Public Works staff is commended for demonstrating clear thinking and fast action.
*Update in unit of measurement has been made since the original distribution of this press release, which previously, incorrectly used "cubic feet per second."
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