A Carrot and Stick Approach to Inflow and Infiltration

A combination of incentives and penalties created success for Duluth I&I program

A Carrot and Stick Approach to Inflow and Infiltration

Convincing homeowners to put their own money behind a private-side inflow-and-infiltration project seems impossible, but one Minnesota utility found a formula that resulted in over 10,000 foundation drain disconnections.

Overall, Duluth has eliminated around 26 million gallons a day of I&I from its system during rain events through private-property I&I reductions and utility projects. Using public education and cost sharing, as well as implementing potential penalties for noncompliance, became a powerful combination for success.

A big part of the program has been inspections, which are voluntary in most cases, but the city isn’t afraid to force homeowners’ hands when necessary.

The Carrot

One of the key issues early on in getting the program off the ground was securing public funding for use on private systems. At the time, using city funds on private property was a nonstarter, but city officials lobbied the state Legislature to create an exception for programs with significant public impact, like this one.

“We based it on the public benefit of removing sewage from the environment,” says Todd Carlson, program coordinator. “If we can remove the I&I, we can keep the sewage contained — we’re not going to have the overflows.”

Duluth is heavily water-centric, so keeping the waterways clean not only has environmental impact, but economic impact as well. Because of that, after a pilot project was approved, the city began putting money toward separation of foundation drains and installation of a sump pump, and eventually for private lateral rehabilitation.

When volunteers weren’t enough to reach its goals for foundation drain disconnections, the city started looking at more persuasive methods.

The Stick

Early on, the city created an ordinance that required disconnection of any and all foundation drains. A public uproar put a swift halt to that action.

“Two weeks later it was rescinded, and the I&I program was shut down because there was so much of the community that said, ‘Wait a minute, I’m not a part of this problem,’” Carlson says. “They didn’t have the knowledge and the information that they needed at that time. It was a tough pill to swallow.”

But that wasn’t the end of I&I mitigation for Duluth. City officials continued to brainstorm ways to push for disconnections. Eventually they found a middle ground.

“There was a lot of stuff happening, so essentially the city took a step back, the task force was developed with community members and stakeholders, and kind of developed how the program would work. Since each house was a little bit different, everybody was going to get an inspection, because we couldn’t blanket it and say everybody gets a sump pump. So that needed staff and time to go to each house.”

Around 26,000 homes would need to be inspected as part of the program. At the time of this revamp, inspections and participation in the program were still voluntary.

A second attempt at forcing participation came with a surcharge for those who refused to allow inspections. That ordinance failed as well because the city found legal issues in forcing citizens to allow government workers into their homes.

An administrative warrant from the Environmental Protection Agency, served to the city in 2004, made it clear that drastic steps were necessary. After the EPA called for Duluth to cease and desist all sewer overflows, the stormwater utility began working through the police department to have search warrants issued to allow foundation drain inspections to occur.

After that, if the city found issues and the homeowner refused to make any changes, it was legal to apply a surcharge to their utility bill. “We would always tell people: I don’t want your money — I just want compliance,” Carlson says. “I just want you to do the right thing. Be part of the solution, not part of the problem.”

The administrative warrant was the first part of negotiating a consent decree that was implemented in 2009 and completed in 2015. It mandated that the city complete 175 lateral rehabs or replacements and 630 foundation drain disconnections annually. Thanks to its innovative program, they generally exceeded those requirements.


The last piece of the puzzle for Duluth was and continues to be ensuring that the actions it has taken so far continue to be successful. To that end, the city has required point-of-sale inspections to check on sump pumps and make sure they are discharging properly.

“The biggest thing was getting those sump pumps discharged far enough away from the house that the water didn’t recycle back into the foundation drains,” Carlson says.

Over time, some homeowners decided they didn’t like having water drain out into their yards. Some have tried to bring the hose back into their house, discharging into a tub or interior drain, which defeats the purpose altogether.

In many cases, residents didn’t realize the effect that actions like this could have. It came down to a fundamental lack of understanding about the difference between the sanitary sewer and stormwater.

Better Together

Carlson emphasizes that the key to success in gaining compliance is working with residents. Maintaining communication, ensuring they understand the issue at hand, and giving them flexibility and input during the process have been integral to the success of its program.

“We really worked hard to accommodate the residents and work with them. You essentially have to build some trust,” he says. “We would meet in their house — we were explaining all sorts of plumbing issues, and talking about storm sewers and how those work, and how the sanitary sewer worked, and where the water goes when they flush toilets — a real sewer 101 education in the basement of their houses.”

Foundation drains, once required by building code in Duluth back in the early days of development, were estimated to contribute 1 gallon of I&I per minute during rain events. Private sewer laterals were contributing 2 gallons per minute.

“So we were providing funding, and we worked with the residents,” Carlson says. “People started to really embrace the program after that.”


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