Spring Hill aldermen unanimously approved a $12 million sewer agreement with Columbia on Monday, Oct. 19.

The Board of Mayor and Aldermen (BOMA) passed Resolution 26-302, authorizing the city to move forward with an interlocal wastewater deal that had been months in the making. The vote completes both sides of the agreement. Columbia's City Council approved its end Oct. 8, as we reported Oct. 15.

Spring Hill will fund and build a 12-inch sewer main from the Spring Hill Reclamation Plant on Mahlon Moore Road to Columbia's system on the northern side of Columbia's city limits, according to the city's announcement. The line will run along Mahlon Moore Road and then follow a Tennessee Valley Authority easement for several miles.

Of the $12 million, $9 million is earmarked for the pipeline. The remaining $3 million will pay for upgrades to the Carter's Creek Pike Pump Station. Spring Hill bears the full cost.

Once built, the main will carry between 500,000 and 1.5 million gallons of wastewater per day to Columbia for treatment. Spring Hill will also pay Columbia a usage rate for that service. The Williamson Herald reported Spring Hill is projected to pay between $21 million and $62 million over 10 years in treatment fees, depending on volume.

Mayor Matt Fitterer said in the city's announcement that the partnership with Columbia is an example of regional cooperation delivering real value for Spring Hill residents. He said the city is planning ahead and investing responsibly in critical infrastructure.

Columbia Mayor Chaz Molder said Spring Hill had a need and Columbia answered the call, according to the Williamson Herald. Columbia City Manager Tony Massey called the deal a sound partnership.

The agreement had been in the works for months. At the BOMA's Feb. 17 meeting, Fitterer told aldermen that Columbia had approved a cost reimbursement related to the project, according to meeting minutes.

Service will not begin until Columbia's new wastewater treatment plant is finished. That plant is under construction and expected to be completed in 2027, according to the Williamson Herald. It will increase Columbia's treatment capacity to 17 million gallons per day.

Main Street Maury reported on X that Spring Hill's sewer moratorium will remain in place until mid-2030, even with the new agreement.