Heavy Rains Cause Sewer Overflows In Duluth

By KBJR News 1

Heavy Rains Cause Sewer Overflows In Duluth

August 2, 2011 Updated Aug 2, 2011 at 1:01 PM CST

Duluth, MN (Northland's NewsCenter) Heavy rains caused sewer overflows early Tuesday morning in the Western Lake Superior Sanitary District’s (WLSSD) collection system in Duluth.

Intensity of the rainstorm varied throughout the region, from nearly 3 inches in the Pike Lake area to about 1.5 inches in western portions of the District.

Confirmed overflows occurred as follows:

Location Address Approx.Start Approx. End Approx.Volume

Polk Street Pump Station 110 Central Ave S. 2:45-4:45 a.m. 53,538 gallons

5th Avenue East Overflow Structure 5th Avenue East and the Lakewalk, Duluth 3:00- 4:45 a.m. 512,000 gallons

The State of Minnesota duty officer was notified of the overflow events.

Peak flow to WLSSD’s wastewater treatment plant was about 133 million gallons per day (MGD) at 4:00 a.m. Tuesday, compared to the average daily flow of 38 MGD.

Storage basins are under construction to eliminate sewer overflows at each of the two locations.

The Polk Street storage facility, a WLSSD project, will be completed later this year.

The city of Duluth is constructing a large storage basin at Third Avenue East and the Lakewalk to hold excess flows from the 5th Avenue East location. It is scheduled for completion in 2012.

“A new million-gallon sanitary sewer overflow storage facility is nearing completion at our Polk Street location,” said Marianne Bohren, WLSSD executive director. “The new storage facility and other upgrades at that location will be operational by November, ending overflows at the site.

“The tremendous surge of water we received at the treatment plant indicates that inflow and infiltration of rain water into the sanitary sewer remains a problem in many areas of the region. Storage basins are a costly, but necessary, part of the solution to prevent sanitary sewer overflows. However, communities in our region must continue to eliminate sources of inflow and infiltration so we can avoid the need for additional basins.”

Residents should avoid contact with any sewer overflow due to the potential for exposure to disease-causing organisms.

Residents are also asked to report any overflow from a manhole.

Storm sewers and sanitary sewers may lift and move manhole covers creating a dangerous fall hazards when the overflow ceases.

Contact WLSSD at 722-3336, extension 301, 24-hours per day to report overflowing manholes or any open manhole.

WLSSD and the City of Duluth are subject to a consent decree with the United States Environmental Protection Agency and the Minnesota Pollution Control Agency to eliminate sanitary sewer overflows to Lake Superior by 2016.

Construction of large storage basins and other improvement projects are ongoing, as well as efforts to prevent inflow and infiltration of rain water from homes and businesses into the sanitary sewer system.

Inflow and infiltration (I&I) is a term used to describe the two ways in which ground and surface waters enter the sanitary sewer system. Most of the communities in the WLSSD service area have two separate sewer systems.

The storm sewer system is intended to help with drainage and carries rainwater and water from melting snow into area creeks and streams where it flows into Lake Superior.

The sanitary sewer system is intended to transport water used in homes and businesses to the treatment plant.

Rainwater does not typically require treatment at the wastewater treatment plant.

When rainwater enters the sanitary sewer system through inflow and infiltration, it can often overwhelm the system and cause sewer overflows.