Wastewater plant in TC needs fixes

Apr. 27—TRAVERSE CITY — Aging parts of the Traverse City Regional Wastewater Treatment Plant need big-bucks fixes, including one piece that's reached a critical point.

It's called a primary header and it distributes waste water flow from part of the plant that removes grit and debris to a series of settlement tanks, where even more solids are removed, city Municipal Utilities Director Art Krueger said.

He told city commissioners Monday that a pipe connected to the primary header a few years ago sprung a leak, and the metal of the header itself is wearing thin.

That leak could have caused a catastrophic failure of the plant's pipe gallery had plant personnel not intervened, according to a study from firm Hubbell, Roth and Clark.

Replacing the primary header could cost around $500,000, Krueger said. But the primary header connects one part of the pretreatment process to another, so a study of how those components are holding up was in order.

"We don't want to move forward after that and possibly change the routing to where we wouldn't need that pipe in the location it is," he said.

More ultrasonic testing is on order for the primary header, and the city's lining up a contractor to encase it in an epoxy wrap to shore it up structurally and buy some time, Krueger said.

Taking a look at the components up- and downstream from that primary header revealed other issues, and Hubbel, Roth and Clark's study estimates they'll cost $14.5 million to fix, plus some additional plumbing work that could run up to $1 million depending on how other components are fixed.

Krueger told commissioners about those issues, like a grit removal system that's old and struggles to keep up when flows are high. Rehabbing it would cost around $900,000 but the firm recommends replacing it with a new system for $4.82 million.

The settlement tanks' concrete walls are holding out strong after 90 years for four of the tanks and 70 for four others, Krueger said. But the sludge-collecting mechanism at the bottom is old and very pricey to replace, and the concrete could start to deteriorate faster in the coming decades. Repairing the existing tanks would be a little more than half the cost as replacing them with new tanks — $3.55 million versus $6.34 million, respectively.

Further downstream, some screw pumps that lift the pretreated water to the next treatment stages might need replacing with a new type of pump to head off more costly repairs, Krueger said. Those submersible pumps are estimated at $1,717,000. And a new screen in the very first stage of debris removal would run about $1,662,000.

The firm's recommendations are based on a present worth analysis, where they account for factors like operations and maintenance costs for 20 years.

Those assumptions drew some scrutiny, with Commissioner Brian McGillivary wanting to see the numbers behind the operations and maintenance estimates.

Too much of the report language seemed more qualitative than quantitative, Commissioner Tim Werner said. He wanted to see more numbers-based rationales behind them, and that led him to question whether some of the recommendations were right.

Plus, some of the issues that only crop up during high flow could be headed off by keeping groundwater and rain water out of the sewer mains, a major issue Krueger recently told commissioners about, Werner said.

"Here we're looking at spending close to $15 million but we're pretty much ignoring that some of that cost is because we're not addressing the infiltration and inflow," he said.

City Manager Marty Colburn said the city would split whatever the cost is with Acme, East Bay, Elmwood, Garfield and Peninsula townships, as they own what amounts to about 40 percent of the plant.

They're part of the Grand Traverse County Board of Public Works, where he'll present the same report and discuss the options at hand.

McGillivary said he was interested in the townships' input — Colburn later noted the city is the plant's "managing partner."

Plus, the city nearly paid off a 19-year-old loan to upgrade the treatment process to use membrane filters, Colburn said. That'll free up the money to pay off any borrowing necessary for these repairs.

Krueger said he applied for a Clean Water State Revolving Loan fund, with a draft plan out for public comment through May 15. City commissioners will hear more input at a public hearing on May 17, and a final plan is due to the state by June 1.

The city would be eligible for funding as soon as Oct. 1, Krueger told Commissioner Ashlea Walter. She wanted to know what options the city had for funding and whether any potential grants would arrive soon enough.

"They do take time and they're not a guarantee, so I would weigh that with some of our other funding options but I don't want to wait too long until there's further major issues with the pipes," she said.

It's city sewer ratepayers who ultimately own the city's portion, McGillivary said. He also wants to see how paying back the loan Krueger applied for would compare to the current bond payment.

"Everybody who pays to have sewage treatment are the people I'm the most concerned about, I want to see what the project impact is going to be on the rates," he said.