Building Sewer System Strength

Iowa city addresses aging infrastructure and tightens up its wastewater system.

Building Sewer System Strength

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Water leaks. Wastewater leaks. Infiltration. Indianola, Iowa, has experienced all of it, but the utility is gaining ground.

The City’s Water Pollution Control department had an awakening in 2009 when the state’s Department of Natural Resources issued a mandate to remove all groundwater from its sewer collections system. For the Warren County seat, a city of 16,000 in south-central Iowa, it was a tall order.

Crews subsequently worked their way through the system, first inspecting and sealing manholes against water infiltration. Then they methodically inspected the network of pipes — one quadrant of the city at a time — searching out leak points in pipe that averages 35 to 40 years old.

Quick action got the process moving in the right direction, and the DNR lifted its mandate in 2014 on the strength of progress made and the community’s pledge to keep reducing inflow and infiltration. City Manager Ryan Waller and wastewater department superintendent Rick Graves have been overseeing the effort to live up to the terms of the consent order since their arrival in 2016 and 2015, respectively.

Public trust

The system’s sewer lines are composed mostly of 8-inch clay with some PVC mixed in. Larger sections of pipe range up to 30 inches in diameter.

Initial inspection of the system turned up lots of lateral line problems, but also significant infusions of groundwater in sewer mains. In 2017, Indianola’s city council approved a regimen of pipe inspections on private properties with penalties for failure to correct discovered problems. Property transactions now require inspection of sewer laterals and hookups.

Inspectors most commonly encounter roof gutters and sump pumps connected to the sanitary sewer system, laterals separated or cracked by tree roots and age, and uncapped cleanout pipes. The inspections on private properties became voluntary in 2018. In the interim, some of the oldest properties were inspected and corrected. The community’s newer housing stock generally harbored fewer improper hookups.

“We still have some issues with laterals,” says Graves. However, City Hall is counting on property buyers volunteering for inspections to protect their investment. “We’re going to move ahead and get our sewer mains buttoned up and go from there.”

Waller says that when he and Graves came onboard with the city, there wasn’t much being done. “So, we had conversations with our community partners at local real estate offices and they had a hand in crafting the inspection ordinance,” he says. “That was a good thing. The question was how we could work with residents and real estate agents in selling our community. The collaborative effort was in the best interests of the property owners and of the department.”

One of Waller’s key guidelines is working with the various components of the community. He refers to the Four C’s — communication, collaboration, community engagement and customer service — in talking about that work.

“The state’s mandate was kind of a heavy hand, and the first smoke testing to find leaks had a negative connotation in the community,” he says. “We have a great team and hosted a community meeting to share with residents what we were doing, showing them that collapsed lines cost them money and that the inspections were doing them a service. We didn’t want to come down heavy-handed, too.”

Engaging with the community had the residual effect of building long-term public trust in the administration and the wastewater department. That makes sewer rate increases more palatable for residents. In fact, Indianola recently raised its rates for the first time in seven years, upping them to a base rate of $18 for the first thousand gallons and $9.85 per thousand gallons after that. Some of the money will help fund the city’s new wastewater treatment plant.

“Nobody likes rate adjustments,” Waller says. “But we’ve not heard many complaints. We’ve had a lot of conversations the last several years. The community understands we can’t get out of meeting state regulations.”

Private partners

While the Water Pollution Control department tackles whatever work it can in-house, the heaviest part of the city’s ongoing and planned infrastructure work will be bid out. Waller, who has worked in the industry for 20 years, says contracting out some services ensures that vital infrastructure is in the best shape possible. 

“We do projects in-house when we have the equipment to do it,” he says. “Our team does a great job televising and cleaning lines and replacing manholes.”

Crews rely on a pair of camera systems for in-house inspections, a CUES push-camera system and an Envirosight Rovver X sewer inspection crawler.

“We do 50,000 feet a year of camera work,” Graves says. “Everyone works at it in rotating shifts, with four operators working in the collections system and another person in the lab.”

The department has also budgeted for the upcoming purchase of a Bobcat Toolcat, which will carry the Envirosight system — along with a Honda generator — to less accessible sewer mains. When it comes to cleaning, crews get the job done with a Vactor 2100 jet/vac rig.

“Sometimes, though, we bid out those jobs, too,” Waller says. “Smoke services is one of the services we typically partner with the private sector to get done.”

Larger projects are prioritized and competitively bid, sometimes even spot repairs. In the last round of bids, a trio of Iowa companies won contracts.

Continued investment

While the city has made great progress, the remaining I&I issues are not negligible. Graves estimates that as much as a million gallons of rainwater still infiltrate the city’s sewer system on a rainy day. “Here’s an example of that. We had about an inch of rain on Nov. 10 of last year and our flows jumped up 700,000 gallons a day for two days and then went right back to normal. An extra 1.4 million gallons of flow — I call it a spike event.”

The city is budgeting $250,000 per year for inflow and infiltration corrective work in an effort to reduce that big number to something more incidental. In 2020, that funded lining of 2,300 feet of pipe in 10 sewer main sections and 50 laterals. In addition, 10 manholes were repaired.

That level of investment in the system will continue for the foreseeable future along with $30,000 a year for replacement of lift station pumps. The type of projects varies from year to year. For example, the current contract calls for additional manhole makeovers, less than a thousand feet of sanitary sewer lining and about 350 feet of storm sewer repair.

A good place

Luckily, the city has the right team in place. Graves came to Indianola after a dozen years of serving as superintendent for two other Iowa sewer systems and is licensed for a variety of wastewater treatment and distribution tasks. “He’s the expert,” Waller says. As such, Graves is well qualified to oversee cross-training of his crew. Cleaning pipe. Repairing pumps. Running the cameras.

The result is a sewer system that, despite ongoing repair and rehabilitation work, is in a pretty good place, Graves says.

Waller concurs. “I was just talking to staff about that. Anything related to municipal work and infrastructure — the work is never done. You say, for example, we have all the streets paved, so the end is in sight, but that’s not possible. Yes, we have more I&I work to do and the storm sewers need a little more TLC, but they’re not in bad shape. We’re sitting pretty nice. We’re good.” 


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