DES MOINES - The cities of Knoxville, Chariton and Des Moines reported wastewater bypasses Monday after storms hit.
In Knoxville, a lightning strike shut down electric power at the wastewater treatment plant, disabling some equipment about 1 p.m. Monday. As a result, partially treated wastewater began flowing into an equalization basin, designed to store excess flows. The basin was already full from rainfall last week, so the city discharged about 6,000 gallons per minute of partially treated wastewater to Competine Creek which flows to Lake Red Rock. Power was restored about 3 p.m. and the bypass was expected to end soon.
A bypass occurred Sunday and Monday in Chariton. Wastewater began bypassing about 3 p.m. Sunday from pumps on the northwest side of town. The problem was not reported to wastewater officials until 7 a.m. Monday. Once reported, the city was able to unplug clogged pumps and quickly stop the bypass. The city estimates up to five gallons per minute bypassed for about 17 hours to Shelton pond which flows into Little White Breast Creek.
In addition, heavy rainfall caused an emergency overflow from Chariton's equalization basin about 3:30 p.m. Monday. The city expects the overflow to continue through Tuesday. The basin flows into Little White Breast Creek.
A third bypass occurred in Des Moines about noon Monday when the city set up a portable pump to bypass untreated wastewater from the 400 block of Hartford St. into a storm drain that leads to the Jackson St. storm water basin. The city bypassed the untreated wastewater to prevent it from backing up into basements in the area. The city estimates about 2,125 gallons bypassed to the Des Moines River upstream of 14th St.
In addition to these bypasses, it is likely that other cities are bypassing partially treated or untreated wastewater. It's important for people in the heavy rainfall areas to avoid contact with swollen streams which may have an elevated bacterial count.The DNR will continue to monitor bypassing and is requiring water monitoring where appropriate.