The question
Does Lebanon need a new wastewater treatment plant? How much more capacity is needed? Where could a new plant go, and who would pay for it?
Plain-English answer
Lebanon has two related wastewater problems. Some problems happen at the treatment plant. Others happen in the network of sewer pipes, manholes, and pump stations that carry sewage to the plant.
The clearest records show that rainwater and groundwater are getting into the sewer system, sewage has overflowed at several locations, some required reports contained errors, and one manhole known as MH5898 overflowed several times.
In March 2026, the Tennessee Department of Environment and Conservation, or TDEC, called MH5898 a chronic overflow point. That means it had enough overflow events to trigger special permit rules. TDEC told Lebanon to consider a limited pause on adding more sewer flow upstream of that location.
TDEC later said two overflow events might be removed from the count because they happened during declared emergencies. That could remove the chronic label and the related pause on new flow. We have not found TDEC's final written decision.
Lebanon has also started building a new equalization basin. This is a large storage basin that temporarily holds extra wastewater during storms until the treatment plant can handle it. The newest approved design holds 8 million gallons. The project is expected to be mostly finished by November 18, 2027.
The records support the need for major wastewater work. They do not yet prove that the current projects will fully solve the problem or show how much safe, reliable capacity is still available for new development.
Helpful terms
- Wastewater: Used water and sewage from homes, businesses, and industries.
- Collection system: The pipes, manholes, and pump stations that move wastewater to the treatment plant.
- Infiltration and inflow, or I&I: Rainwater or groundwater that gets into sewer pipes and adds extra flow to the system.
- Sanitary sewer overflow: Sewage that escapes from the sewer system before reaching the treatment plant.
- Equalization basin: A storage basin that holds extra wastewater during high-flow periods, especially during storms.
- Design capacity: The amount of wastewater a plant was built and permitted to treat under normal design conditions.
Why this matters
- It affects whether new homes and businesses can safely connect to the sewer system.
- It affects the risk of sewage overflows and water pollution.
- It may affect utility bills, taxes, and public debt.
- A new facility could affect nearby neighborhoods through odor, traffic, noise, or land use.
- It raises the question of whether current residents or new development should pay more of the cost.
What is confirmed
- The current permit lists the treatment plant's design capacity as 10 million gallons per day.
- A March 26, 2026 TDEC Notice of Violation found reporting errors, treatment-limit violations, sewer overflows, releases, and repeated problems at MH5898.
- TDEC reported 20 sewer overflows and 23 releases since the prior inspection. Some had already been covered by earlier enforcement actions.
- Lebanon received permission to begin the equalization-basin and pump-station project.
- The city expects the project to be mostly complete by November 18, 2027.
- On June 4, 2026, TDEC approved a revised design for an 8-million-gallon basin and a transfer pump station.
- A separate city committee is reviewing possible sites for added or replacement treatment capacity.
- The committee can make recommendations, but City Council must approve property purchases, financing, and the final project.
What remains unclear
- Whether TDEC officially kept or removed MH5898's chronic-overflow label.
- How much wastewater the system can reliably handle during normal weather.
- How much it can handle during heavy rain.
- How much capacity has already been promised to approved projects that are not built yet.
- Whether the final answer will be a replacement plant, a second plant, an expansion, more pipe repairs, or a mix of several projects.
- Why the proposed new basin was reduced from 10 million gallons to 8 million gallons, other than lowering the cost.
- Whether the 8-million-gallon basin will provide enough protection before and after the expected 2027 completion date.
- The full list of possible plant sites and why each site was added, ranked, removed, or rejected.
- The full construction cost, yearly operating cost, financing cost, possible rate increases, and how much new development would pay.
Document review and differences
Did MH5898 remain a chronic overflow point?
The March 2026 notice called MH5898 a chronic overflow point. That triggered a requirement for Lebanon to consider a limited pause on new sewer flow upstream of the manhole.
A May 11 letter said TDEC was considering removing two emergency-related events from the count. TDEC said this would lower the count to three and remove the chronic label and related pause.
Assessment: UNCLEAR. The May letter described a possible decision. We have not found the final decision.
Why did the proposed basin change from 10 million gallons to 8 million gallons?
Earlier records described a 10-million-gallon new basin. TDEC's June 4 approval describes a revised 8-million-gallon basin and says the size was reduced to lower project costs.
This new basin is separate from the plant's existing storage basin and separate from the plant's 10-million-gallon-per-day treatment rating.
Assessment: CONFIRMED CHANGE. The newest approved design is 8 million gallons. The engineering reason for why 8 million gallons is enough has not yet been found.
Has sewer repair work reduced extra stormwater flow?
Lebanon said it inspected about 82,300 feet of sewer pipe. The city also said one repaired area had about 59 million gallons less flow during the first 145 days of 2026 than during the same period in 2025. The city described this as a 38 percent drop.
Assessment: SUPPORTED. These numbers appear in the city's report. We have not found a separate review that confirms them.
Does a 10-million-gallon-per-day permit mean that much capacity is still available?
No. The permit says what the plant was designed to treat. It does not tell us how much unused capacity is available today.
To answer that question, the city would need to account for current use, heavy-rain flows, system limits, and sewer capacity already promised to approved development.
Assessment: UNCLEAR. The permit number alone does not show how many new connections the system can safely accept.
Recent regulatory timeline
- March 26, 2026: TDEC issued a Notice of Violation after inspecting the treatment plant and sewer system.
- May 11, 2026: TDEC said it might remove two emergency-related events from the MH5898 count.
- May 13, 2026: Lebanon held a preconstruction meeting for the new basin and pump-station project.
- June 2, 2026: Lebanon sent TDEC its project schedule, repair information, rainfall analysis, and flow data.
- June 4, 2026: TDEC approved revised plans for an 8-million-gallon basin and transfer pump station.
- June 22, 2026: TDEC approved a short sewer extension for Lawrence Row. The approval warned that the new connection could not cause or add to a sewer overflow or overload the treatment plant.
What to watch as decisions are made
These are questions for public review. They are not accusations of wrongdoing.
- Does TDEC issue a clear final decision about MH5898?
- Does the city explain why the proposed basin changed from 10 million gallons to 8 million gallons?
- Are new developments approved without a written statement showing enough sewer capacity?
- Are engineering reports and site scores released before major votes?
- Do project costs change without a clear public explanation?
- Will current customers pay most of the cost for infrastructure needed by new growth?
Questions citizens can ask
- How much wastewater reaches the plant on a normal day?
- How high does the flow rise during heavy rain?
- How much safe, reliable capacity remains today?
- How much capacity has already been promised to approved projects that are not built yet?
- What is TDEC's final decision about MH5898?
- Why was the new basin reduced from 10 million gallons to 8 million gallons?
- What other solutions were studied?
- What is the full cost, including land, pipelines, borrowing, operation, and maintenance?
- How much would current customers pay, and how much would new development pay?
- When will site scores, rankings, maps, and reasons for removing sites be released?
How hard was the evidence to find?
Very difficult. A resident must search city agendas, TDEC databases, permit numbers, engineering approvals, meeting videos, and separate public-record systems. A record can be public and still be very hard to find or understand.
Sources reviewed so far
Most TDEC records do not have simple, permanent web pages. Open the official viewer below, search permit TN0028754, and match the document title and date listed here.
Open TDEC's official data viewers · Read TDEC's guide to public wastewater records
- City of Lebanon Sanitary Sewer Overflow Evaluation materials.
- March 26, 2026: TDEC Notice of Violation covering the plant and sewer-overflow inspections. Search TN0028754 and “2026 NOV for CEI & SSO.”
- May 11, 2026: TDEC letter about possibly removing MH5898's chronic-overflow label. Search TN0028754 and “Field Office Reply to 2026 NOV Response.”
- June 2, 2026: Lebanon's MH5898 response, project schedule, and sewer-repair information. Search TN0028754 and “2026 Chronic Overflow Point Response Letter.”
- June 4, 2026: TDEC approval for the revised 8-million-gallon basin and pump station. Search project number 25.0688R.
- June 22, 2026: TDEC approval for the Lawrence Row sewer extension. Search project number 26.0321.
- City of Lebanon Agenda Center for site-selection committee agendas and meeting materials.
Records still needed for a final conclusion
- TDEC's final decision about MH5898.
- The city record that explains and approves the change from a 10-million-gallon basin to an 8-million-gallon basin.
- Current engineering numbers showing how much reliable capacity remains.
- The amount of sewer capacity already promised to approved but unbuilt development.
- The complete site list, score sheets, rankings, and reasons sites were removed.
- Project cost estimates, the financing plan, possible rate changes, and how costs would be divided.
What would change the conclusion?
Our conclusion could change if newer engineering records show that the current system has enough reliable capacity, if repairs and the new basin greatly reduce overflow risk, if a less expensive solution meets the same needs, or if new TDEC records change the status of MH5898 or other system limits.