The Metropolitan Council is preparing to buy a suburban wastewater treatment plant for the first time in four decades, bringing a fast-growing corner of northwest Hennepin County into its massive regional network.

The city of Rogers has requested that the council take over its nearly 60-year-old treatment plant, which will be phased out for a new regional Crow River plant at the western border of the county. If the council approves the plan, it will operate the Rogers plant for 10 years before transitioning service to the larger facility — also serving nearby cities of Dayton and Corcoran.

The council now operates eight treatment plants and collects wastewater through a 600-mile network of large sewer pipes spanning the seven-county metro area. In its early years, the council purchased municipal plants regularly, consolidating 33 of them into a more efficient regional network. Its last purchase was Waconia in 1978.

City officials in Rogers said tighter environmental regulations would have required major investments in the city’s aging plant, which did not make sense given the plans for a new regional facility. City public works Superintendent John Seifert said the city has been in talks with the council about this issue since the early 1990s.

“We’ve been asked for the last … almost 30 years to make additional investments by our residents and businesses waiting for the regional system to reach us,” Seifert said.

The council’s regional wastewater system has expanded outward over time, serving new areas of urban growth. Areas southeast of Rogers like Maple Grove send their wastewater to the massive Metropolitan Wastewater Plant in St. Paul, but the pipe that recently reached a corner of Rogers can’t handle all the anticipated growth in the area.

“Rogers is one of the larger cities in the metro area that is not part of the system,” said Rogers City Administrator Steve Stahmer. “Rogers has been developing and growing on its own without having the benefit of that regional infrastructure.”

Council staff said they do not know how much the agency will pay for the Rogers plant — a value calculated under a formula in state law — but the price will be available before a public hearing in January. The cost of the new Crow River regional plant has not been determined, though past estimates pegged it at $100 million.

The council paid about $1.7 million several years ago to purchase a 105-acre site for that plant.

“It reflects growth. It reflects potential changes to the regulatory compliance picture that we see in the future,” said Jeannine Clancy, assistant general manager in the council’s wastewater division. “And I believe it reflects the need to think about communities around Rogers, as well, who are also growing and need wastewater system capacity.”

Clancy presented the acquisition last week to the council’s environment committee, which voted unanimously to hold a public hearing. The council expects to hold a public hearing after Jan. 15, with a vote on the final agreement in late February.

Two of the Met Council’s wastewater projects at the edge of the metro area have stumbled in recent years, though both involved uncommon projects in rural areas outside the contiguous wastewater system. . The council built a new wastewater plant in East Bethel and a collection pipe to Elko New Market to accommodate expected growth, but they ended up costing the council more after development fell short of projections.