ENFIELD — The town of Enfield would have to spend between $35 million and $39 million to break free of its sewer agreement with Lebanon and build a wastewater treatment plant within the town’s borders, according to a draft study released this week.

The study, conducted by Massachusetts-based DPC Engineering, concluded that the price to build new sewer lines, a physical plant and other associated improvements are “unaffordable” absent major federal grants.

Consultants recommended that Enfield instead continue to pay Lebanon to treat some its wastewater and revisit the idea of constructing a standalone facility only if fees from the neighboring city “rise suddenly.”

The findings didn’t appear to surprise Interim Town Manager Jack Wozmak, the former administrator of Cheshire County, which operates a wastewater treatment plant in Jaffrey, N.H.

He told Enfield’s Selectboard on Monday night that the steps required to build a new facility — laying new pipes, purchasing land and negotiating ways to dispose of treated waste — are “prohibitively expensive.”

“Operating a wastewater treatment plant is very expensive no matter how you slice it,” Wozmak said.

Sewage from more than 600 homes connected to Enfield’s sewer lines is sent to the treatment facility in West Lebanon under an inter-municipal agreement that dates back to the 1980s. Other homes in town rely on septic systems.

While the arrangement allows Enfield to forgo the cost of building and staffing its own plant, it has at times led to conflict between the two communities.

Under the agreement, Enfield is subject to rate increases approved by the Lebanon City Council — 7.2% in 2021 — which sometimes results in complaints about the loss of local control.

The two municipalities also butted heads over Lebanon’s “sewer development charge,” which assesses a one-time fee for new buildings based on how many gallons of waste they are expected to produce.

Enfield initially contested the 2019 charge, arguing new hookups are the town’s customers and not Lebanon’s, but eventually relented after a legal review earlier this year.

“The best deal you could have is to have somebody else treat sewage for you,” Wozmak told the Selectboard.

“You haven’t got a bad deal,” he added. “You’ve got about the only deal you can have, to be honest with you.”

If Enfield were to build a treatment plant, there are two options available to the town using different filtration methods, according to the DPS Engineering study.

One would cost just over $39 million to build and come with nearly $1 million annual operating costs, while the other would cost about $35 million and require about $1.2 million to maintain, the study said.

Both would be situated on a property on Evenchance Road, which is off Route 4A, and require the relocation of sewer lines near the Enfield and Lebanon town line.

Meanwhile, maintaining the agreement with Lebanon costs about $742,000 a year in equipment and maintenance costs, the consultants estimated.

Town officials said Monday that it’s unlikely they’ll move forward with plans to build a treatment plant or reroute the sewer.

Some said the study, while necessary, should silence critics who argue that Enfield should break off from Lebanon’s system or have pondered whether doing so would be cheaper.

“Nobody was going to believe that this was our best option unless we did this due diligence piece,” Selectboard member Kate Stewart said of the inter-municipal agreement.

But, she added, the price tag quoted in the study is “still shocking.”

Tim Camerato can be reached at tcamerato@vnews.com or 603-727-3223.