At least half the Southdale Library site in Edina is likely to be sold for development as part of the project to rebuild the library, according to plans presented Thursday to Hennepin County commissioners.

County officials prepared four alternatives for the future of the 7.7-acre site, which straddles the border of Edina and Richfield. The existing building opened in 1973, though the library occupies only a small part of it.

Of the four plans, officials recommended the option to build a two-story library on the northwest quadrant of the site, at the intersection of W. 70th Street and York Avenue. A lot with possible underground parking would border Xerxes Avenue.

The plan would include the sale of at least 3.9 acres on the southern half of the site for future development. The cost of the land is estimated at $2 million an acre, said Margo Geffen with the county’s Community Works Department.

The county has budgeted an estimated $50 million to build the new library, which would measure about 55,000 square feet and be comparable in size to the current space. Minneapolis architecture firm MSR Design was selected to create the design.

Other proposals suggested limiting the library to one quadrant and selling the rest for development; having the library span more than half the property and selling the rest; and building a library on 5 acres while using the rest for parkland.

The recommended alternative includes building a trail to connect the library to Adams Hill Park just south of the site. Green space surrounding the library would be added, a request from library users. But County Board Chairwoman Jan Callison said the county “is not going to deliver a park to the city of Edina.”

“I don’t want people to walk away thinking we’re overpromising on green space,” she said. “There is an investment to be recouped here.”

Building designs are expected to be presented to the board for a vote sometime in November. “Once that happens, the real technical design work starts,” County Administrator David Hough said.

Hough said he doesn’t believe the remaining land will be sold until the library has opened. What that future development will be is unknown.

Commissioner Marion Greene said she’d like to see some form of affordable housing go on the site.

“I have a little … low-level nervousness that we’re letting properties slip through our fingers and not being aggressive, as we will regret later, about building affordable housing,” she said.

The existing building is likely to be demolished in the fall of 2019, with construction starting on the new building at the end of that year. The new library is planned to open in the summer of 2021.

Hennepin County has worked on the redevelopment of the Southdale library, a chunky white structure fronted by columns and surrounded by parking lots, since at least 2015. The building has housed county facilities and courtrooms.

Plans to relocate the courtrooms to Bloomington were scrapped late last year. Instead, Richfield and Bloomington residents with court business will have to go to the Hennepin County Government Center in downtown Minneapolis after the Southdale building is razed.