The Tenleytown Safeway is being purchased by the Georgetown Day School and could close in 10 months. (Jeffrey MacMillan/For The Washington Post)

Georgetown Day School, one of the region’s top private schools, announced a massive campus consolidation plan Thursday with the purchase of the Tenleytown Safeway and the former Martens Volvo/Volkswagen car dealership properties.

At a cost of about $40 million, the deals provide Georgetown Day, an institution whose students and alumni include the sons and daughters of some of the most prominent movers and shakers in the Washington area, with space to bring together its lower, middle and upper schools onto one Northwest Washington campus.

The school’s lower and middle schools are now on MacArthur Boulevard, a campus about four miles away that the school said it might sell to finance its consolidation.

“Georgetown Day School has been a member of the Tenleytown community for 28 years,” said Russell Shaw, head of Georgetown Day. “We value the relationship we have with our neighbors and are excited about this unique opportunity to enhance the education our students receive and the neighborhood we call home.”

The school is in the early stages of planning how to use the properties, according to school spokeswoman Alison Grasheim, but school leaders envision the Safeway site, at 4203 Davenport St. NW, as a new campus and the neighboring dealership property, which fronts Wisconsin Avenue, as a commercial development that would support the school financially.

“We had hoped for the opportunity for everyone to be on the same campus,” Grasheim said. “We just have felt that it makes for a better school community and better connects students through grade levels.”

School officials also see the move as a way to bolster Georgetown Day’s financial sustainability, allowing it to hold tuition increases in check and maintain competitive faculty salaries. Not only will the school save operating expenses by consolidating two campuses into one, but the new commercial development probably will produce a revenue stream far into the future.

“As we look ahead, there are multiple opportunities to consider that could bring in significant revenue for the school through smart, careful planning and development of the sites,” school officials wrote in an e-mail to parents Thursday afternoon.

Both the dealership and the grocery store will remain open for at least 10 months through lease agreements with the school, and terms of the sale prevent the construction of a new grocery store on the site.

The decision to sell marks an abrupt turnaround for Safeway, as it had been contemplating a mixed-use development of the Tenleytown location that would have included a much larger store with apartments on top. Its departure from the neighborhood belies otherwise tightening grocery competition in the city, with Giant Food, Harris Teeter, Whole Foods Market, Trader Joe’s and independent chains all opening or seeking to open new stores.

While the grocer’s preference to add apartments when building new stores has been well-received in D.C. neighborhoods such as Petworth and Mount Vernon Square, it caused strife among Tenleytown neighbors, raising the prospect of a lengthy and expensive approval process.

Safeway spokesman Craig Muckle said the company got numerous offers from the school before coming to a deal. “Until GDS made its offer, we were continuing efforts to redevelop the existing store,” Muckle said.

Winning zoning approval has not been easy for some developers in the area; a plan to redevelop a Giant Food store with housing nearby took more than 10 years to meet approval. Muckle said that the disagreements weren’t the deciding factor in the sale but that “the offer presented by GDS provided a much quicker solution than development.”

Getting city and neighborhood buy-in for changes to the corridor now falls to Georgetown Day officials, who said they will solicit input from parents and alumni as well as the broader Tenleytown community as they formulate plans. They estimate that it will take five to seven years to plan for and develop the properties.

“It’s part of the culture of GDS to be inclusive and work through things in a collaborative manner,” said Michael Gottdenker, president of the school’s board of trustees. “In this case I think that will serve us quite well. We fully intend to engage with our neighbors and the GDS community itself.”

Matthew Frumin, chair of Advisory Neighborhood Commission 3E, said that after exhaustive discussions with Safeway about redevelopment plans, the announcement came as a surprise.

“Our expectation was that we were going to proceed down the path of mixed-use development,” Frumin said. “I think the first thing is going to be surprise and the second thing is going to be to take a deep breath to understand what their plans are for the Safeway site and the Martens site. And I think we just don’t know enough right now.”

D.C. Council member Mary M. Cheh (D-Ward 3), the mother of two GDS alumni, said she looks forward to seeing the school’s development plans.

“I very much want to see that part of Wisconsin livened up a bit,” Cheh said. She also said she’s hopeful that moving the school’s MacArthur Boulevard campus will alleviate traffic along that corridor during the morning rush.

The school’s board of trustees includes considerable real estate expertise. Marc Glosserman, a 1992 alumnus, is the chief executive of the restaurant company that owns the Penn Quarter restaurant Hill Country. He is also the son of one of the most powerful executives in Washington real estate, Michael J. Glosserman, who is serving as a real estate adviser to the school and is a managing partner of the JBG Cos., based in Chevy Chase, Md.

The MacArthur Boulevard campus, should the school decide to sell it, offers a rare 3.3.-acre development site near the banks of the Potomac River in one of the city’s toniest neighborhoods. The D.C. government assesses it at $14.5 million.

Residential builder Marc Dubick, who teamed with Safeway on its Petworth project and is working with the grocer to redevelop its Palisades store, said he was stunned by Safeway’s decision to sell.

But he also recently completed 34 townhouses on MacArthur Boulevard, selling them for $1 million to $1.9 million, and said developers would be eager to try something similar at the GDS campus if it were sold.

“It clearly has to be some type of housing,” he said.