Heavy rains were causing infiltration at the Factory Street Pump Station in Ypsilanti, Mich., which receives all the city’s sewage flows.The Ypsilanti Community Utilities Authority (YCUA), an independent agency that owns the water and sewer mains, began a systematic inspection of the city’s 800 manholes. Inspections included documenting flows on dry and wet days to pinpoint infiltration sources, then televising four areas where the mains ran under the Huron River.“One river crossing in particular seemed to be the culprit,” says Mike Shaffer, transmission and distribution foreman for the YCUA service department. “When we inspected the line, we found four root
