7-minute read
Most people don’t think about what happens after they flush their toilets, but wastewater managers are acutely aware that one of the largest networks carrying the city’s sewage — the almost 80-year-old Western Trunk Line — is too narrow, has lots of inflow and infiltration and is crumbling in places.
It needs to be replaced, but doing so will be costly and complicated. The existing 2.6-mile line runs under homes and roads — including more than a quarter mile of Harden Boulevard — so the city of Lakeland needed to find a new route as it planned a new pipeline.
The city approved a route last year that was estimated in May to cost almost $82 million. However, city project manager Guy Taylor and engineers from Garney Construction recently identified an alternate path that could save the city $7.9 million and shorten the project by six months.
Time and money: The cost estimate is now closer to $74 million, according to Water Utilities Engineering Manager Robby Kniss. He said funds for the “generational project” will come from three sources:
- $17.8 million in American Rescue Plan Act (ARPA) funds.
- About $15 million from wastewater impact fees.
- The balance from low-interest state loans and/or a bond issue.
Construction of the 42-inch-diameter line is expected to begin in May 2025 and be complete by December 2026, Taylor said. However, upgrades to smaller collector lines will go beyond then.
Path of less resistance: The updated sewer route still runs due south from an undeveloped parcel near Herschell Street, skirting the Southwest Sports Complex and following Lotus Avenue and Woodbrook Boulevard. However, instead of crossing Harden Boulevard at Forest Park Street and passing in front of Lakeland Christian School, the new path will cross Harden just south of West Beacon Road.
Kniss said the change requires extra survey and design work — including adding a new pump station and force main to the project. But more of the route is undeveloped, helping to cut costs and timelines. The alternate path also avoids tearing up one of the roads to Lakeland Christian School, potentially disrupting traffic for weeks.
Taylor called the switch a “seismic shift” when he first alerted commissioners about it in July.
Last week, the City Commission unanimously approved a change order authorizing $1.05 million for the extra engineering. Several commissioners praised the staff. “To hear that — not only efficiency and time, but cost savings — is wonderful. Wonderful work,” said Commissioner Mike Musick.
Kniss said the city will send letters to homeowners and host community meetings about the project early next year, before construction begins.
See the new route
Why it’s urgent: The Western Trunk Line was built in the 1950s as a 36-inch non-reinforced concrete pipeline. It was rehabbed in the 1980s with a slip liner that narrowed it, making it closer to 30 inches in diameter. But now that liner is failing, Kniss said.
- Treatment plant working overtime — Each day, roughly 3.5 million gallons of wastewater pass through the Western Trunk Line. But that volume can swell to almost 20 million gallons after major rain events like Tropical Storm Debby last month. The extra flow from groundwater seeping into the pipes goes to the Glendale Wastewater Reclamation Facility in southeast Lakeland, which is permitted for only 13.7 million gallons per day. It is also costly to treat extra water unnecessarily.
- Sewage spills — A greater concern is the potential for pipes that are already near capacity to start backing up because of unexpected flow. Kniss said that can push untreated wastewater up through manholes and into people’s toilets and drains. That happened in Pinellas County three weeks ago when 4.4 million gallons of sewage — enough to fill six Olympic-sized swimming pools — flooded a residential neighborhood.
- Spot fixes are disruptive — Every month or so, the city has to close a road for emergency sewer repairs. Lake Morton Drive was closed on Thursday for that reason. Other closures this year have included North Crystal Lake Drive, Carleton Street, South Florida Avenue, Orange Street and Griffin Road. The unexpected closures disrupt drivers and businesses, and are costly for the city.
Solution wasn’t obvious: Looking at satellite maps, the new route seems logical. Some disruption is inevitable when workers use heavy machinery to excavate deep open trenches. But it’s faster and cheaper to break through dirt than asphalt, and it’s less disruptive to work on lightly traveled two-lane roads and grassy areas behind homes than a major thoroughfare in front of a busy school. So why wasn’t the new path chosen from the start?
Taylor told commissioners that the original design sought to put the replacement line as close to the original Western Trunk as possible. And that might have happened if the project had followed the traditional three-step “design-bid-build” construction process.
But this project has been the city’s first using an integrated “progressive design-build” method, with city officials and contractors collaborating daily from the beginning.
“One of the things we discovered early is that 90% of the flow that the Western Trunk carries originates on the west side of Harden Boulevard,” Taylor said. That made it logical to reimagine the route and keep it west of Harden for an extra half mile.
The shift will require a new pump station and force main. But there is a lot of city-owned right-of-way along the new route, adding to the overall cost savings.
A second act for the old line? Much of the original Western Trunk Line will be capped and filled once the new line is complete. But the portion east of Harden may get a second act.
There is no practical way to look inside sewer pipes that are full of murky liquid, Taylor said. In emergencies, bypass pumps can divert flow from specific segments for a short time, but that process is expensive.
With only 10% as much flow, engineers should be able to use remote cameras to scope the insides of the old pipes. Kniss said the city might be able to repurpose the conduits around San Gully Road and the Citrus Center Colony mobile home community by inserting new 24-inch pipes or modern liner material.
Some wrinkles to work out: City officials are optimistic about the project, but the design phase is only 60% to 70% complete. There are still some issues to work out.
- Private systems — Rerouting the Western Trunk Line will affect collector sewers that tie into the current system. The city is responsible for upgrading and connecting lines that it owns. But Kniss said there are five mobile home communities with privately-owned systems. The city is working on developer incentives to help defray the cost of new connections.
- Soil quality — The land along the new route appears to be well-suited for the project. But not all soils work equally well for deep excavation and fill replacement. Sandy soil conforms around pipes, while clay can clump into large boulders and then break up and sink over time. If engineers discover “unsuitable fill” along the route, it may add to the cost.
- Utility conflicts — Gravity sewers require a steady downhill slope. The new pipes will start around 10-12 feet deep and angle downward gradually, reaching a depth of 20-25 feet by the time they reach the pump station. Engineers try to identify any possible obstacles early, because having to go up or down six inches can make a huge difference extended over several miles.
Utility lines are a concern. Utility companies only have to report where their lines are — not how deep they are. Sometimes lines have enough slack to be lifted. But running new lines or cutting and splicing can be costly, especially fiber optic cables that have many strands.
- Loan limits — The city can borrow up to $20 million a year from the Florida Department of Environmental Protection’s State Revolving Fund program. However, Kniss said another Lakeland project is likely to use much of that funding this year.
The city’s cost for the Western Trunk Line has ballooned to more than $41 million. It would take more than two years for the city to borrow all of the money it needs from the state, but it can’t delay the project that long. The ARPA funds must be committed by December 2024 and spent by December 2026. So Lakeland may have to consider another funding source like a bond issue.
Kniss said he expects to bring a funding proposal to the commission in the next three months.
latest news
Something went wrong. Please refresh the page and/or try again.