May 19, 2005

Storms Lead to Wastewater Bypasses Across Iowa

Heavy rainfall over the past week has led to a number of wastewater bypasses throughout the state of Iowa.
When wastewater systems could not keep up with the rainfall, many communities bypassed untreated wastewater to streams or rivers to prevent untreated sewage from backing up into residential homes.
When basements and streets are inundated with intense storms, a sewer system can fill rapidly, mixing stormwater with sewage and exceeding the sewer capacity. The system will overflow at low points or be manually pumped to avoid health concerns of flooded basements.
While bypassing wastewater does not remove all health risks, bypassing to prevent backup into homes presents less of a human health risk. Bypassing to a stream can help dilute the wastewater, while sewage in basements would be undiluted.
"While bypassing needs to be avoided, and some systems do need to be updated, these types of extreme events can overwhelm even well designed waste treatment facilities," said Barb Lynch, supervisor of the DNR's field services.
Precipitation-related bypasses must be reported to the DNR in a monthly report. Bypasses not caused by precipitation must be reported to the DNR within 12 hours of discovery.

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