Buhl city leaders urged to investigate sources of inflow and infiltration

BUHL—The City of Buhl is experiencing unexplained spikes of Inflow and Infiltration (I & I) increasing the volume of water entering its wastewater collection system that could potentially jeopardize the authorization of Minnesota Pollution Control Agency (MPCA) permits required to expand the city’s sewer system, according to Norm Miranda, Executive Director of the Central Iron Range Sanitary Sewer District (CIRSSD).

Inflow occurs when groundwater seeps into sewer pipes through cracks, leaky pipes and/or defective manholes, according to information provided by the CIRSSD. Meanwhile infiltration is stormwater that enters through rain leads, basement sump pumps or foundations illegally connected to the city sanitary sewer.

The CIRSSD processes wastewater from its member communities of Buhl, Kinney, Chisholm, Great Scott Township and Minnesota Discovery Center, at its Craig S. Pulford Wastewater Treatment Plant, located just east of Chisholm in Balkan Township.

While addressing the Buhl City Council last Tuesday, Miranda said it’s not the long-term base flow at the CIRSSD Buhl Lift Station that is a cause of concern—it’s instantaneous spikes of water entering the system that creates a concern.

Miranda told the council that during a rain event from December 23 flows spiked to a rate of 495,500 gallons from the Buhl Lift Station entering the Craig S. Pulford wastewater treatment plant. He also shared information from similar spikes incurred in May 2023 and February 2024.

While all communities have some I & I and most likely will never get to zero, Miranda urged Buhl city leaders to do some exploring to help identify any “low hanging fruit” that could be remedied and reduce flows into the Buhl lift station.

Some measures Miranda suggested include: reviewing the Buhl’s sewer ordinance, manhole inspections, flow monitoring, smoke testing, dye testing, and pipe televising. Miranda said some of the items, i.e. smoke testing and televising had been done in the past, but it’s been long enough to review them to see if anything had changed.

Buhl City Clerk Tony Jeffries, via email on Tuesday, told the Mesabi Tribune that Buhl is strongly considering all of the techniques/technologies mentioned by Miranda, and perhaps even some more.

Miranda on Monday told the Mesabi Tribune that the main problem is the spikes come all at once.

“We don’t get 495,000 spread over a 24-hour period,” Miranda wrote in an email.

Miranda, at the council meeting last week, used a comparison of water being funneled from a hole in the bottom of a one-gallon bucket to empty it into a five gallon bucket versus taking all of the water from a five-gallon bucket and pouring it into a one-gallon bucket all at once.

In the past eight years, Miranda estimated that Buhl/Kinney paid an additional $20,203 extra, based on the .50 per gallon cities are charged by legislation for an equipment replacement fund.

Buhl isn’t the only city working to combat additional I & I, Miranda noted.

Additional flows resulting from I & I go beyond additional charges to the replacement fund charges of .50 cents per 1,000 gallons. He noted there’s extra Operations and Maintenance costs (O & M) including premature wearing of machinery and equipment, and additional chemicals needed to process the water.