Albert Lea officials are asking residents to discharge their sump pumps outside because of the recent wet weather.

The city’s wastewater treatment plant processed almost five times the normal flow of water last week during heavy rainfall, and the system is still experiencing high flows, said Public Works Director Steven Jahnke.

He said on average, the wastewater treatment plant flow rate is about 3.5 million gallons per day, but last week with heavy rains, the treatment plant reached a flow rate of about 15 million gallons a day. On Wednesday, the flow rate was still double its average rate at about 8 million gallons.

“Although we are not experiencing problems, the city is concerned if we have another heavy rainfall event that we will experience backups and be forced to bypass from the sanitary sewer system to prevent basement backups,” Jahnke said.

He said this has happened in the past where the city experienced backups that required pumping from the sanitary sewer to the lakes.

A 70 percent chance of showers is forecast for Friday, and a 50 percent chance of rain is expected Saturday.

To reduce the frequency of bypassing, the Albert Lea City Council in 1999 authorized inspections of basements to identify sump pumps and to remove the discharge of the pumps from the sanitary sewer, he said.

In 2007, the council also authorized a sanitary sewer line inspection to look for lines that were connected.

Jahnke said both programs have caused significant reductions in inflow and infiltration. Inflow refers to storm water that enters the system directly from sources such as sump pumps, drains and even streams, and infiltration refers to the storm water that is entering the system through cracks in pipes or joints.

Inflow and infiltration can be a problem because they increase the load on a sanitary sewer system — which was created to treat wastewater — and can eventually cause both the wastewater and the storm water in the system to flow backward through the pipe, flooding basements or causing manholes to pop open and release wastewater into the streets.

“The city’s sewer collection and treatment systems cannot keep up during storm events if residents’ sump pumps discharge to the sanitary sewer,” the release stated.

Discharging sump pumps outside at this time of year will also make it easier for the city’s wastewater treatment plant to comply with permit limitations, reduce the wear and tear on equipment and lower treatment costs, the release added.

For more information, contact Jahnke at 377-4325.